Monday, August 24, 2009
AAL2
AAL2 provides bandwidth-efficient transmission of low-rate, short and variable packets in delay sensitive applications. It supports VBR and CBR. AAL2 also provides for variable payload within cells and across cells. AAL type 2 is subdivided into the Common Part Sublayer (CPS ) and the Service Specific Convergence Sublayer (SSCS ).
Third Generation Cellular Networks
Third Generation Cellular Networks (commonly referred to as 3G) represent the next phase in the evolution of cellular technology, evolution from the analog systems (1st generation) and digital systems (2nd generation). 3G networks will represent a shift from voice-centric services to converged services, including voice, data, video, fax and so forth.
UMTS is the dominant 3G solution being developed, representing an evolution from the GSM network standards, interoperating with a GSM core network. The 3G will implement a new access network, utilizing both improved radio interfaces and different technologies for the interface between the access network and the radio network.
UMTS will use a wideband CDMA technology for transmission, and a more efficient modulation than GSM. This will allow UMTS to reach higher utilization, and offer higher bandwidth to the end-user. UMTS also implements an ATM infrastructure for the wireline interface, using both AAL2 and AAL5 adaptations; AAL2 for real-time traffic and AAL5 for data and signaling.
UMTS is the dominant 3G solution being developed, representing an evolution from the GSM network standards, interoperating with a GSM core network. The 3G will implement a new access network, utilizing both improved radio interfaces and different technologies for the interface between the access network and the radio network.
UMTS will use a wideband CDMA technology for transmission, and a more efficient modulation than GSM. This will allow UMTS to reach higher utilization, and offer higher bandwidth to the end-user. UMTS also implements an ATM infrastructure for the wireline interface, using both AAL2 and AAL5 adaptations; AAL2 for real-time traffic and AAL5 for data and signaling.
2008 Global Digital Economy - M-Commerce, E-Commerce & E-Payments
E-commerce is now an important part of the economy, particularly in the developed markets. While e-commerce is still in its infancy in many emerging markets, this is set to change in the coming years especially in China. In 2008 China now has the highest number of Internet users in the world, overtaking the USA. E-commerce growth in the USA remains strong however, with China also offering significant opportunities for those operating in the e-commerce space.
Worldwide the number of Internet users has now reached around 1.4 billion and billions will be spent by consumers during 2008 on online retail. While the economic slowdown will most likely curb e-commerce growth somewhat over the next couple of years, particularly spending on online advertising, there is evidence that so far the online retail market has remained steady due mostly to the lower prices offered via online shopping.
Internet banking has slowly become more popular around the world, with 30% or more of Internet users utilising such services in some markets. However many online banking websites have at least one potential design weakness that could leave users vulnerable to cyber attacks. Improved bank security measures over the last couple of years, such as the introduction of home chip and pin devices is helping to combat this issue.
In the next few years the total entertainment and publishing industry (including offline and online) is expected to be worth more than $2 trillion – driven in particular by a wave of growth in online video games, gambling, music, social networking/UGC, and online video. In recent times sales of digital music, mostly via the Internet, have increased by more that 30%; in contrast sales of CD and DVDs continue to decline. Online video consumption is also beginning to produce promising results and advertisers have begun to seriously take note. Pay-to-own downloading is particularly popular and new business models in this area are expected to emerge over the next few years. Travel and adult content services are also popular with more growth expected ahead.
Mobile commerce is potentially important for a wide range of industries, including telecommunications, IT, finance, retail and the media, as well as for end-users. It will work best in those areas where it can emphasise the core virtue of mobile networks – convenience. However while there are good applications, the technologies and business models to date have not been well suited to mass market applications. The regulatory environment has also held this market up. This is beginning to change as banks and merchants collaborate with mobile operators. Applications around contactless cards using Near Field Communications are also being developed around the world. Focus has also turned to the developing markets, where mobile phones are being viewed as an opportunity to reach the masses that would not otherwise use m-payment or m-banking services.
In countries such as Kenya and India, national mobile banking systems are thriving and they are literally popping up around the world as well. In Kenya, 3 million out of Vodafone's 10 million subscribers are using mobile banking services and Vodafone is rapidly rolling the service out in other countries as well.
This annual report provides an insight and analyses into the trends and developments taking place in the m-commerce and e-commerce sectors. The report provides analyses of the trends and issues impacting upon the growth of e-commerce, including e-banking, e-payments and online advertising sectors. Analyses of the developments taking place in mobile commerce are also provided, along with information on m-payment and m-banking. Statistics and forecasts for both the e-commerce and m-commerce markets are provided. The report also includes valuable insights and statistics on the developments taking place on a regional level including North America, Latin America, Europe, Middle East, Africa and Asia Pacific.
Worldwide the number of Internet users has now reached around 1.4 billion and billions will be spent by consumers during 2008 on online retail. While the economic slowdown will most likely curb e-commerce growth somewhat over the next couple of years, particularly spending on online advertising, there is evidence that so far the online retail market has remained steady due mostly to the lower prices offered via online shopping.
Internet banking has slowly become more popular around the world, with 30% or more of Internet users utilising such services in some markets. However many online banking websites have at least one potential design weakness that could leave users vulnerable to cyber attacks. Improved bank security measures over the last couple of years, such as the introduction of home chip and pin devices is helping to combat this issue.
In the next few years the total entertainment and publishing industry (including offline and online) is expected to be worth more than $2 trillion – driven in particular by a wave of growth in online video games, gambling, music, social networking/UGC, and online video. In recent times sales of digital music, mostly via the Internet, have increased by more that 30%; in contrast sales of CD and DVDs continue to decline. Online video consumption is also beginning to produce promising results and advertisers have begun to seriously take note. Pay-to-own downloading is particularly popular and new business models in this area are expected to emerge over the next few years. Travel and adult content services are also popular with more growth expected ahead.
Mobile commerce is potentially important for a wide range of industries, including telecommunications, IT, finance, retail and the media, as well as for end-users. It will work best in those areas where it can emphasise the core virtue of mobile networks – convenience. However while there are good applications, the technologies and business models to date have not been well suited to mass market applications. The regulatory environment has also held this market up. This is beginning to change as banks and merchants collaborate with mobile operators. Applications around contactless cards using Near Field Communications are also being developed around the world. Focus has also turned to the developing markets, where mobile phones are being viewed as an opportunity to reach the masses that would not otherwise use m-payment or m-banking services.
In countries such as Kenya and India, national mobile banking systems are thriving and they are literally popping up around the world as well. In Kenya, 3 million out of Vodafone's 10 million subscribers are using mobile banking services and Vodafone is rapidly rolling the service out in other countries as well.
This annual report provides an insight and analyses into the trends and developments taking place in the m-commerce and e-commerce sectors. The report provides analyses of the trends and issues impacting upon the growth of e-commerce, including e-banking, e-payments and online advertising sectors. Analyses of the developments taking place in mobile commerce are also provided, along with information on m-payment and m-banking. Statistics and forecasts for both the e-commerce and m-commerce markets are provided. The report also includes valuable insights and statistics on the developments taking place on a regional level including North America, Latin America, Europe, Middle East, Africa and Asia Pacific.
Mobile Communications and Mobile Data Technologies
This report is a technical introduction, for people without an engineering background, to digital cellular mobile technologies. These are the basis of huge and growing industries for voice and increasingly data communications, with cellular handsets becoming the most widely used electronic product in history.
We begin with an introduction to the 1G and early digital technologies AMPS, IS-136 TDMA and IS-95 CDMA. We discuss GSM and its high speed data enhancements, including HSCSD GPRS and EDGE. We discuss the UMTS (Universal Mobile Telecommunications Service) Wideband Code Division Multiple Access (WCDMA) 3G technologies. These are based on the GSM network architecture and together with GSM are the most widely used technologies on a global basis.
We also discuss the Japanese FOMA WCDMA system, which was the basis for UMTS WCDMA, and CDMA2000 and its high speed data enhancement EV-DO (Evolution Data Only) which are the dominant 3G technologies in North America and many other non-European countries. We provide tutorials on convolutional coding and the spreading and scrambling processes which are at the heart of Code Division Multiple Access (CDMA) spread-spectrum techniques.
We discuss services which operate similarly or identically over all 2.5G and 3G networks, including SMS text messaging, Multimedia Messaging Service (MMS) and Wireless Application Protocol (WAP). We discuss the IP Media Subsystem (IMS) – a centrally managed network architecture which is the basis for providing a number of services including instant messaging with presence, Push-to-Talk over Cellular (PoC), VoIP and location based services, irrespective of the underlying 2.5G or 3G network technology.
Base-stations and their backhaul network are the most expensive part of cellular systems. We discuss the various approaches to base-stations, including the conventional large, tower-based ‘macro-node’, and alternatives for smaller areas and enclosed spaces, including ‘micro-nodes’ and ‘pico-nodes’. We conclude this discussion with a detailed evaluation of the emerging ‘femtocell’ technology: the ability to place a small base-station in a home or office, using the owner’s ADSL or HFC cable modem service for backhaul. This is based on the new Generic Access Network (GAN) standards, which arose initially from the desire to achieve Fixed Mobile Convergence (FMC) via unlicensed frequencies, with Bluetooth and WiFi approaches.
We discuss the long-term development of the two major 3G technologies into 4G mobile systems, with similar OFDM-based modulation schemes and performance to fixed and mobile WiMAX. We consider the challenge the 4G development of UMTS poses to CDMA2000’s 4G Ultra Mobile Broadband and to the widespread adoption of WiMAX.
Broadcasting or multicasting to handheld devices can be achieved with a unidirectional system with separate frequencies such as Eureka 147 Terrestrial Digital Mobile Broadcasting (T-DMB), DVB-H or Qualcomm’s FLO (Forward Link Only). Alternatively, it can be achieved with data packets within the cellular technology, perhaps with OFDM modulation to increase data density, as is possible with EV-DO. We discuss these and other approaches to this important addition to mobile technology.
We also discuss the major audio visual coding technologies, otherwise known as data compression, for sound, video and multimedia material. An increasing number of these technologies are utilised in 3G services and in mobile broadcasting.
Cellular mobile technology is a complex and rapidly developing field. This report is intended to give non-specialists a comprehensive technical introduction to current and emerging mobile cellular technologies. This report is intended to enable readers to understand current usage and foresee likely developments relevant to their own domains, such as telecommunications regulation, investment and management.
We begin with an introduction to the 1G and early digital technologies AMPS, IS-136 TDMA and IS-95 CDMA. We discuss GSM and its high speed data enhancements, including HSCSD GPRS and EDGE. We discuss the UMTS (Universal Mobile Telecommunications Service) Wideband Code Division Multiple Access (WCDMA) 3G technologies. These are based on the GSM network architecture and together with GSM are the most widely used technologies on a global basis.
We also discuss the Japanese FOMA WCDMA system, which was the basis for UMTS WCDMA, and CDMA2000 and its high speed data enhancement EV-DO (Evolution Data Only) which are the dominant 3G technologies in North America and many other non-European countries. We provide tutorials on convolutional coding and the spreading and scrambling processes which are at the heart of Code Division Multiple Access (CDMA) spread-spectrum techniques.
We discuss services which operate similarly or identically over all 2.5G and 3G networks, including SMS text messaging, Multimedia Messaging Service (MMS) and Wireless Application Protocol (WAP). We discuss the IP Media Subsystem (IMS) – a centrally managed network architecture which is the basis for providing a number of services including instant messaging with presence, Push-to-Talk over Cellular (PoC), VoIP and location based services, irrespective of the underlying 2.5G or 3G network technology.
Base-stations and their backhaul network are the most expensive part of cellular systems. We discuss the various approaches to base-stations, including the conventional large, tower-based ‘macro-node’, and alternatives for smaller areas and enclosed spaces, including ‘micro-nodes’ and ‘pico-nodes’. We conclude this discussion with a detailed evaluation of the emerging ‘femtocell’ technology: the ability to place a small base-station in a home or office, using the owner’s ADSL or HFC cable modem service for backhaul. This is based on the new Generic Access Network (GAN) standards, which arose initially from the desire to achieve Fixed Mobile Convergence (FMC) via unlicensed frequencies, with Bluetooth and WiFi approaches.
We discuss the long-term development of the two major 3G technologies into 4G mobile systems, with similar OFDM-based modulation schemes and performance to fixed and mobile WiMAX. We consider the challenge the 4G development of UMTS poses to CDMA2000’s 4G Ultra Mobile Broadband and to the widespread adoption of WiMAX.
Broadcasting or multicasting to handheld devices can be achieved with a unidirectional system with separate frequencies such as Eureka 147 Terrestrial Digital Mobile Broadcasting (T-DMB), DVB-H or Qualcomm’s FLO (Forward Link Only). Alternatively, it can be achieved with data packets within the cellular technology, perhaps with OFDM modulation to increase data density, as is possible with EV-DO. We discuss these and other approaches to this important addition to mobile technology.
We also discuss the major audio visual coding technologies, otherwise known as data compression, for sound, video and multimedia material. An increasing number of these technologies are utilised in 3G services and in mobile broadcasting.
Cellular mobile technology is a complex and rapidly developing field. This report is intended to give non-specialists a comprehensive technical introduction to current and emerging mobile cellular technologies. This report is intended to enable readers to understand current usage and foresee likely developments relevant to their own domains, such as telecommunications regulation, investment and management.
3G and UMTS Technology
Mobile data communications is evolving quickly because of Internet, Intranet, Laptops, PDAs and increased requirements of workforce mobility. 3G UMTS will be the commercial convergence of fixed line telephony, mobile, Internet and computer technology. New technologies are required to deliver high speed location and mobile terminal specific content to users. The emergence of new technologies thus provides an opportunity for a similar boom what the computer industry had in 1980s, and Internet and wireless voice had in 1990s.
The main IMT-2000 standardisation effort was to create a new air interface that would increase frequency usage efficiency. The WCDMA air interface was selected for paired frequency bands (FDD operation) and TDCDMA (TDD operation) for unpaired spectrum. 3G CDMA2000 standard was created to support IS-95 evolution.
The UMTS transport network is required to handle high data traffic. A number of factors were considered when selecting a transport protocol: bandwidth efficiency, quality of service, standardisation stability, speech delay sensitivity and the permitted maximum number of concurrent users. In the UMTS network, ATM (Asynchronous Transfer Mode) is defined for the connection between UTRAN and the core network and may also be used within the core network. In addition to the IMT-2000 frame many new standards will be integrated as part of the next generation mobile systems. Bluetooth and other close range communication protocols and several different operating systems will be used in mobiles. Internet will come to mobiles with WAP, i-mode and XML protocols. 3G development has helped to start the standardisation and development of large family of technologies.
This section covers some of the core UMTS technologies and it will be updated regularly
The main IMT-2000 standardisation effort was to create a new air interface that would increase frequency usage efficiency. The WCDMA air interface was selected for paired frequency bands (FDD operation) and TDCDMA (TDD operation) for unpaired spectrum. 3G CDMA2000 standard was created to support IS-95 evolution.
The UMTS transport network is required to handle high data traffic. A number of factors were considered when selecting a transport protocol: bandwidth efficiency, quality of service, standardisation stability, speech delay sensitivity and the permitted maximum number of concurrent users. In the UMTS network, ATM (Asynchronous Transfer Mode) is defined for the connection between UTRAN and the core network and may also be used within the core network. In addition to the IMT-2000 frame many new standards will be integrated as part of the next generation mobile systems. Bluetooth and other close range communication protocols and several different operating systems will be used in mobiles. Internet will come to mobiles with WAP, i-mode and XML protocols. 3G development has helped to start the standardisation and development of large family of technologies.
This section covers some of the core UMTS technologies and it will be updated regularly
3G and UMTS Technology
Mobile data communications is evolving quickly because of Internet, Intranet, Laptops, PDAs and increased requirements of workforce mobility. 3G UMTS will be the commercial convergence of fixed line telephony, mobile, Internet and computer technology. New technologies are required to deliver high speed location and mobile terminal specific content to users. The emergence of new technologies thus provides an opportunity for a similar boom what the computer industry had in 1980s, and Internet and wireless voice had in 1990s.
The main IMT-2000 standardisation effort was to create a new air interface that would increase frequency usage efficiency. The WCDMA air interface was selected for paired frequency bands (FDD operation) and TDCDMA (TDD operation) for unpaired spectrum. 3G CDMA2000 standard was created to support IS-95 evolution.
The UMTS transport network is required to handle high data traffic. A number of factors were considered when selecting a transport protocol: bandwidth efficiency, quality of service, standardisation stability, speech delay sensitivity and the permitted maximum number of concurrent users. In the UMTS network, ATM (Asynchronous Transfer Mode) is defined for the connection between UTRAN and the core network and may also be used within the core network. In addition to the IMT-2000 frame many new standards will be integrated as part of the next generation mobile systems. Bluetooth and other close range communication protocols and several different operating systems will be used in mobiles. Internet will come to mobiles with WAP, i-mode and XML protocols. 3G development has helped to start the standardisation and development of large family of technologies.
This section covers some of the core UMTS technologies and it will be updated regularly
The main IMT-2000 standardisation effort was to create a new air interface that would increase frequency usage efficiency. The WCDMA air interface was selected for paired frequency bands (FDD operation) and TDCDMA (TDD operation) for unpaired spectrum. 3G CDMA2000 standard was created to support IS-95 evolution.
The UMTS transport network is required to handle high data traffic. A number of factors were considered when selecting a transport protocol: bandwidth efficiency, quality of service, standardisation stability, speech delay sensitivity and the permitted maximum number of concurrent users. In the UMTS network, ATM (Asynchronous Transfer Mode) is defined for the connection between UTRAN and the core network and may also be used within the core network. In addition to the IMT-2000 frame many new standards will be integrated as part of the next generation mobile systems. Bluetooth and other close range communication protocols and several different operating systems will be used in mobiles. Internet will come to mobiles with WAP, i-mode and XML protocols. 3G development has helped to start the standardisation and development of large family of technologies.
This section covers some of the core UMTS technologies and it will be updated regularly
3G and UMTS Technology
Mobile data communications is evolving quickly because of Internet, Intranet, Laptops, PDAs and increased requirements of workforce mobility. 3G UMTS will be the commercial convergence of fixed line telephony, mobile, Internet and computer technology. New technologies are required to deliver high speed location and mobile terminal specific content to users. The emergence of new technologies thus provides an opportunity for a similar boom what the computer industry had in 1980s, and Internet and wireless voice had in 1990s.
The main IMT-2000 standardisation effort was to create a new air interface that would increase frequency usage efficiency. The WCDMA air interface was selected for paired frequency bands (FDD operation) and TDCDMA (TDD operation) for unpaired spectrum. 3G CDMA2000 standard was created to support IS-95 evolution.
The UMTS transport network is required to handle high data traffic. A number of factors were considered when selecting a transport protocol: bandwidth efficiency, quality of service, standardisation stability, speech delay sensitivity and the permitted maximum number of concurrent users. In the UMTS network, ATM (Asynchronous Transfer Mode) is defined for the connection between UTRAN and the core network and may also be used within the core network. In addition to the IMT-2000 frame many new standards will be integrated as part of the next generation mobile systems. Bluetooth and other close range communication protocols and several different operating systems will be used in mobiles. Internet will come to mobiles with WAP, i-mode and XML protocols. 3G development has helped to start the standardisation and development of large family of technologies.
This section covers some of the core UMTS technologies and it will be updated regularly
The main IMT-2000 standardisation effort was to create a new air interface that would increase frequency usage efficiency. The WCDMA air interface was selected for paired frequency bands (FDD operation) and TDCDMA (TDD operation) for unpaired spectrum. 3G CDMA2000 standard was created to support IS-95 evolution.
The UMTS transport network is required to handle high data traffic. A number of factors were considered when selecting a transport protocol: bandwidth efficiency, quality of service, standardisation stability, speech delay sensitivity and the permitted maximum number of concurrent users. In the UMTS network, ATM (Asynchronous Transfer Mode) is defined for the connection between UTRAN and the core network and may also be used within the core network. In addition to the IMT-2000 frame many new standards will be integrated as part of the next generation mobile systems. Bluetooth and other close range communication protocols and several different operating systems will be used in mobiles. Internet will come to mobiles with WAP, i-mode and XML protocols. 3G development has helped to start the standardisation and development of large family of technologies.
This section covers some of the core UMTS technologies and it will be updated regularly
Circuit Switching vs. Packet Switching
Traditional connections for voice communications require a physical path connecting the users at the two ends of the line, and that path stays open until the conversation ends. This method of connecting a transmitter and receiver by giving them exclusive access to a direct connection is called circuit switching.
Most modern networking technology is radically different from this traditional model because it uses packet data. Packet data is information which is:
1.chopped into pieces (packets),
2.given a destination address,
3.mixed with other data from other sources,
4.transmitted over a line with all the other data,
5.reconstituted at the other end.
Packet-switched networks chop the telephone conversation into discrete "packets" of data like pieces in a jigsaw puzzle, and those pieces are reassembled to recreate the original conversation. Packet data was originally developed as the technology behind the Internet.
A data packet.
The major part of a packet's contents is reserved for the data to be transmitted. This part is called the payload. In general, the data to be transmitted is arbitrarily chopped-up into payloads of the same size. At the start of the packet is a smaller area called a header. The header is vital because the header contains the address of the packet's intended recipient. This means that packets from many different phone users can be mixed into the same transmission channel, and correctly sorted at the other end. There is no longer a need for a constant, exclusive, direct channel between the sender and the receiver.
Packet data is added to the channel only when there is something to send, and the user is only charged for the amount of data sent. For example, when reading a small article, the user will only pay for what's been sent or received. However, both the sender and the receiver get the impression of a communications channel which is "always on".
On the downside, packets can only be added to the channel where there is an empty slot in the channel, leading to the fact that a guaranteed speed cannot be given. The resultant delays pose a problem for voice transmission over packet networks, and is the reason why internet pages can be slow to load.
Most modern networking technology is radically different from this traditional model because it uses packet data. Packet data is information which is:
1.chopped into pieces (packets),
2.given a destination address,
3.mixed with other data from other sources,
4.transmitted over a line with all the other data,
5.reconstituted at the other end.
Packet-switched networks chop the telephone conversation into discrete "packets" of data like pieces in a jigsaw puzzle, and those pieces are reassembled to recreate the original conversation. Packet data was originally developed as the technology behind the Internet.
A data packet.
The major part of a packet's contents is reserved for the data to be transmitted. This part is called the payload. In general, the data to be transmitted is arbitrarily chopped-up into payloads of the same size. At the start of the packet is a smaller area called a header. The header is vital because the header contains the address of the packet's intended recipient. This means that packets from many different phone users can be mixed into the same transmission channel, and correctly sorted at the other end. There is no longer a need for a constant, exclusive, direct channel between the sender and the receiver.
Packet data is added to the channel only when there is something to send, and the user is only charged for the amount of data sent. For example, when reading a small article, the user will only pay for what's been sent or received. However, both the sender and the receiver get the impression of a communications channel which is "always on".
On the downside, packets can only be added to the channel where there is an empty slot in the channel, leading to the fact that a guaranteed speed cannot be given. The resultant delays pose a problem for voice transmission over packet networks, and is the reason why internet pages can be slow to load.
TDMA vs. CDMA
We have considered how a mobile phone can send and receive calls at the same time (via an uplink and a downlink). Now we will examine how many users can be multiplexed into the same channel (i.e., share the channel) without getting interference from other users, a capability called multiple access. For 3G technology, there are basically two competing technologies to achieve multiple access: TDMA and CDMA.
TDMA is Time Division Multiple Access. It works by dividing a single radio frequency into many small time slots. Each caller is assigned a specific time slot for transmission. Again, because of the rapid switching, each caller has the impression of having exclusive use of the channel.
CDMA is Code Division Multiple Access. CDMA works by giving each user a unique code. The signals from all the users can then be spread over a wide frequency band. The transmitting frequency for any one user is not fixed but is allowed to vary within the limits of the band. The receiver has knowledge of the sender's unique code, and is therefore able to extract the correct signal no matter what the frequency.
This technique of spreading a signal over a wide frequency band is known as spread spectrum. The advantage of spread spectrum is that it is resistant to interference - if a source of interference blocks one frequency, the signal can still get through on another frequency. Spread spectrum signals are therefore difficult to jam, and it is not surprising that this technology was developed for military uses.
Finally, let's consider another robust technology originally developed by the military which is finding application with 3G: packet switching.
TDMA is Time Division Multiple Access. It works by dividing a single radio frequency into many small time slots. Each caller is assigned a specific time slot for transmission. Again, because of the rapid switching, each caller has the impression of having exclusive use of the channel.
CDMA is Code Division Multiple Access. CDMA works by giving each user a unique code. The signals from all the users can then be spread over a wide frequency band. The transmitting frequency for any one user is not fixed but is allowed to vary within the limits of the band. The receiver has knowledge of the sender's unique code, and is therefore able to extract the correct signal no matter what the frequency.
This technique of spreading a signal over a wide frequency band is known as spread spectrum. The advantage of spread spectrum is that it is resistant to interference - if a source of interference blocks one frequency, the signal can still get through on another frequency. Spread spectrum signals are therefore difficult to jam, and it is not surprising that this technology was developed for military uses.
Finally, let's consider another robust technology originally developed by the military which is finding application with 3G: packet switching.
Achievements at 3G Mobile
Currently capable of making live TD-SCDMA voice and data calls, the SoftFone-LCR chipset is also featured as the core component in the DTivy(TM)--A Series reference design from Datang Mobile, the developer of the TD-SCDMA standard. Designed through a collaborate effort between Analog Devices and Datang Mobile, the DTivy--A Series reference design is a complete hardware and software solution providing significant BOM savings and faster time-to-market to manufacturers of next-generation 3G TD-SCDMA products such as high-end camera phones, camcorder phones, multimedia phones, and video phones.
Also at the summit, Lining Wang of Analog Devices RF and wireless systems group, will lead a technical presentation on delivering next-generation mobile devices through software and semiconductor innovation. Mr. Wang's presentation will cover challenges faced by handset designers and highlight technology solutions that incorporate reconfigurable analog functions and software-based radio architectures. The presentation will take place on Wednesday, June 29 at 4:40 p.m. local time.
"We are very excited with the industry momentum that is continuing to build around the TD-SCDMA standard as well as our SoftFone-LCR chipset," said Christian Kermarrec, vice president, RF and wireless systems, Analog Devices, Inc. "Because TD-SCDMA uses unpaired frequency bands and is very efficient in its use of spectrum, we believe that it is a good underlying technology for 3G cellular networks in China."
The China 3G Mobile International Summit & Exhibition is intended to bring together leading mobile operators and service providers, infrastructure providers, chipset suppliers, handset developers, content providers and application developers from China and around the world. Discussions will focus on the hottest issues for China in launching 3G, including policies and regulatory initiatives for the 3G market, case studies and lessons from leading international 3G operator deployments, as well as strategies for developing the market for new 3G mobile services and applications in China.
Also at the summit, Lining Wang of Analog Devices RF and wireless systems group, will lead a technical presentation on delivering next-generation mobile devices through software and semiconductor innovation. Mr. Wang's presentation will cover challenges faced by handset designers and highlight technology solutions that incorporate reconfigurable analog functions and software-based radio architectures. The presentation will take place on Wednesday, June 29 at 4:40 p.m. local time.
"We are very excited with the industry momentum that is continuing to build around the TD-SCDMA standard as well as our SoftFone-LCR chipset," said Christian Kermarrec, vice president, RF and wireless systems, Analog Devices, Inc. "Because TD-SCDMA uses unpaired frequency bands and is very efficient in its use of spectrum, we believe that it is a good underlying technology for 3G cellular networks in China."
The China 3G Mobile International Summit & Exhibition is intended to bring together leading mobile operators and service providers, infrastructure providers, chipset suppliers, handset developers, content providers and application developers from China and around the world. Discussions will focus on the hottest issues for China in launching 3G, including policies and regulatory initiatives for the 3G market, case studies and lessons from leading international 3G operator deployments, as well as strategies for developing the market for new 3G mobile services and applications in China.
CDMA 3G Variants (in the IMT-2000 Family)
The primary CDMA variants that will be used in IMT-2000 3G networks are W-CDMA (Wideband CDMA) and cdma2000, which are similar but not the same, so that W-CDMA handsets will not work with cdma2000 handsets and visa versa.
W-CDMA (Wideband CDMA)
W-CDMA is the competitor to cdma2000 and one of two 3G standards that makes use of a wider spectrum than CDMA and therefore can transmit and receive information for faster and more efficiently. Co-developed by NTT DoCoMo, it is being backed by most European mobile operators and is expected to compete with cdma2000 to be the de facto 3G standard
W-CDMA (Wideband CDMA)
W-CDMA is the competitor to cdma2000 and one of two 3G standards that makes use of a wider spectrum than CDMA and therefore can transmit and receive information for faster and more efficiently. Co-developed by NTT DoCoMo, it is being backed by most European mobile operators and is expected to compete with cdma2000 to be the de facto 3G standard
Outdoor wireless mesh technology
Outdoor wireless mesh technology addresses the growing municipal Wi-Fi market. Municipalities, service providers, universities and multi-site commercial organizations are revolutionizing they way they move voice, video and data traffic by incorporating wireless mesh networks into their overall IP networking strategies. Wireless Mesh networks are resilient, in that there are no single points of failure. Based on the mature 802.11 wireless standard, mesh networks are highly reliable and capable of communicating with millions of wireless devices currently in use. Finally, mesh networks feature dynamic route capability and are “self-healing”. Thus, they are easy to deploy and manage – and affordable. Their inherent mesh architecture eliminates the line-of-sight requirement of older outdoor wireless technologies.
Cisco Wireless Mesh ATP’s are “selected” by Cisco and must have a proven track record in integrating RF/Radio solutions with IP networks. Venture’s 22-year track record of engineering, deploying and supporting complex networks and information systems coupled with Venture’s extensive Cisco networking certifications makes Venture a strong player in the Wireless Mesh arena.
Cisco Wireless Mesh ATP’s are “selected” by Cisco and must have a proven track record in integrating RF/Radio solutions with IP networks. Venture’s 22-year track record of engineering, deploying and supporting complex networks and information systems coupled with Venture’s extensive Cisco networking certifications makes Venture a strong player in the Wireless Mesh arena.
Monday, August 17, 2009
General Packet Radio Service(GPRS)
General packet radio service (GPRS) is a packet oriented mobile data service available to users of the 2G cellular communication systems global system for mobile communications (GSM), as well as in the 3G systems. In the 2G systems, GPRS provides data rates of 56-114 kbit/s.
GPRS data transfer is typically charged per megabyte of traffic transferred, while data communication via traditional circuit switching is billed per minute of connection time, independent of whether the user actually is using the capacity or is in an idle state. GPRS is a best-effort packet switched service, as opposed to circuit switching, where a certain quality of service (QoS) is guaranteed during the connection for non-mobile users.
2G cellular systems combined with GPRS are often described as 2.5G, that is, a technology between the second (2G) and third (3G) generations of mobile telephony. It provides moderate speed data transfer, by using unused time division multiple access (TDMA) channels in, for example, the GSM system. Originally there was some thought to extend GPRS to cover other standards, but instead those networks are being converted to use the GSM standard, so that GSM is the only kind of network where GPRS is in use. GPRS is integrated into GSM Release 97 and newer releases. It was originally standardized by European Telecommunications Standards Institute (ETSI), but now by the 3rd Generation Partnership Project (3GPP).
GPRS was developed as a GSM response to the earlier CDPD and i-mode packet switched cellular technologies
GPRS data transfer is typically charged per megabyte of traffic transferred, while data communication via traditional circuit switching is billed per minute of connection time, independent of whether the user actually is using the capacity or is in an idle state. GPRS is a best-effort packet switched service, as opposed to circuit switching, where a certain quality of service (QoS) is guaranteed during the connection for non-mobile users.
2G cellular systems combined with GPRS are often described as 2.5G, that is, a technology between the second (2G) and third (3G) generations of mobile telephony. It provides moderate speed data transfer, by using unused time division multiple access (TDMA) channels in, for example, the GSM system. Originally there was some thought to extend GPRS to cover other standards, but instead those networks are being converted to use the GSM standard, so that GSM is the only kind of network where GPRS is in use. GPRS is integrated into GSM Release 97 and newer releases. It was originally standardized by European Telecommunications Standards Institute (ETSI), but now by the 3rd Generation Partnership Project (3GPP).
GPRS was developed as a GSM response to the earlier CDPD and i-mode packet switched cellular technologies
Thursday, May 21, 2009
IEEE 802.11d
IEEE 802.11d-2001 or 802.11d, is an amendment to the IEEE 802.11 specification that adds support for "additional regulatory domains". This support includes the addition of a country information element to beacons, probe requests, and probe responses. The country information elements simplifies the creation of 802.11 wireless access points and client devices that meet the different regulations enforced in various parts of the world. The amendment has been incorporated into the published IEEE 802.11-2007 standard.
802.11 is a set of IEEE standards that govern wireless networking transmission methods. They are commonly used today in their 802.11a, 802.11b, and 802.11g versions to provide wireless connectivity in the home, office and some commercial establishments.
802.11d is a wireless specification for operation in additional regulatory domains. This supplement to the 802.11 specifications defines the physical layer requirements: • Channelization • Hopping patterns • New values for current MIB attributes • Future requirements to extend the operation of 802.11 WLANs to new regulatory domains (countries).
The current 802.11 standard defines operation in only a few regulatory domains (countries). This supplement adds the requirements and definitions necessary to allow 802.11 WLAN equipment to operate in markets not served by the current standard. Enable the 802.11d feature/option if you are operating in one of these "additional regulatory domains
802.11 is a set of IEEE standards that govern wireless networking transmission methods. They are commonly used today in their 802.11a, 802.11b, and 802.11g versions to provide wireless connectivity in the home, office and some commercial establishments.
802.11d is a wireless specification for operation in additional regulatory domains. This supplement to the 802.11 specifications defines the physical layer requirements: • Channelization • Hopping patterns • New values for current MIB attributes • Future requirements to extend the operation of 802.11 WLANs to new regulatory domains (countries).
The current 802.11 standard defines operation in only a few regulatory domains (countries). This supplement adds the requirements and definitions necessary to allow 802.11 WLAN equipment to operate in markets not served by the current standard. Enable the 802.11d feature/option if you are operating in one of these "additional regulatory domains
Frame aggregation
Frame aggregation is a feature of the IEEE 802.11e and 802.11n wireless LAN standards that increases throughput by sending two or more data frames in a single transmission.
Every frame transmitted by an 802.11 device has a significant amount of overhead, including radio level headers, media access control (MAC) frame fields, interframe spacing, and acknowledgment of transmitted frames. At the highest data rates, this overhead can consume more bandwidth than the payload data frame.[1] To address this issue, the draft 802.11n standard defines two types of frame aggregation: Mac Service Data Unit (MSDU) aggregation and Message Protocol Data Unit (MPDU) aggregation. Both types group several data frames into one large frame. Because management information needs to be specified only once per frame, the ratio of payload data to the total volume of data is higher, allowing higher throughput.
Every frame transmitted by an 802.11 device has a significant amount of overhead, including radio level headers, media access control (MAC) frame fields, interframe spacing, and acknowledgment of transmitted frames. At the highest data rates, this overhead can consume more bandwidth than the payload data frame.[1] To address this issue, the draft 802.11n standard defines two types of frame aggregation: Mac Service Data Unit (MSDU) aggregation and Message Protocol Data Unit (MPDU) aggregation. Both types group several data frames into one large frame. Because management information needs to be specified only once per frame, the ratio of payload data to the total volume of data is higher, allowing higher throughput.
IEEE 802.11h
IEEE 802.11h-2003, or just 802.11h, refers to the amendment added to the IEEE 802.11 standard for Spectrum and Transmit Power Management Extensions. It solves problems like interference with satellites and radar using the same 5 GHz frequency band. It was originally designed to address European regulations but is now applicable in many other countries. The standard provides Dynamic Frequency Selection (DFS) and Transmit Power Control (TPC) to the 802.11a MAC. It has been integrated into the full IEEE 802.11-2007 standard.
IEEE 802.11 is a set of IEEE standards that govern wireless networking transmission methods. They are commonly used today in their 802.11a, 802.11b, and 802.11g versions to provide wireless connectivity in the home, office, and some commercial establishments
IEEE 802.11 is a set of IEEE standards that govern wireless networking transmission methods. They are commonly used today in their 802.11a, 802.11b, and 802.11g versions to provide wireless connectivity in the home, office, and some commercial establishments
IEEE 802.11i
IEEE 802.11i-2004 or 802.11i is an amendment to the original IEEE 802.11 standard specifying security mechanisms for wireless networks. It replaced the short Authentication and privacy clause of the original standard with a detailed Security clause, in the process deprecating the broken WEP. The amendment was later incorporated into the published IEEE 802.11-2007 standard.
The draft standard was ratified on 24 June 2004, and supersedes the previous security specification, Wired Equivalent Privacy (WEP), which was shown to have severe security weaknesses. Wi-Fi Protected Access (WPA) had previously been introduced by the Wi-Fi Alliance as an intermediate solution to WEP insecurities. WPA implemented a subset of 802.11i. The Wi-Fi Alliance refers to their approved, interoperable implementation of the full 802.11i as WPA2, also called RSN (Robust Security Network). 802.11i makes use of the Advanced Encryption Standard (AES) block cipher, whereas WEP and WPA use the RC4 stream cipher.
The 802.11i architecture contains the following components: 802.1X for authentication (entailing the use of EAP and an authentication server), RSN for keeping track of associations, and AES-based CCMP to provide confidentiality, integrity and origin authentication. Another important element of the authentication process is the four-way handshake, explained below
The draft standard was ratified on 24 June 2004, and supersedes the previous security specification, Wired Equivalent Privacy (WEP), which was shown to have severe security weaknesses. Wi-Fi Protected Access (WPA) had previously been introduced by the Wi-Fi Alliance as an intermediate solution to WEP insecurities. WPA implemented a subset of 802.11i. The Wi-Fi Alliance refers to their approved, interoperable implementation of the full 802.11i as WPA2, also called RSN (Robust Security Network). 802.11i makes use of the Advanced Encryption Standard (AES) block cipher, whereas WEP and WPA use the RC4 stream cipher.
The 802.11i architecture contains the following components: 802.1X for authentication (entailing the use of EAP and an authentication server), RSN for keeping track of associations, and AES-based CCMP to provide confidentiality, integrity and origin authentication. Another important element of the authentication process is the four-way handshake, explained below
IEEE 802.11k
IEEE 802.11k-2008 is an amendment to IEEE 802.11-2007 standard for radio resource management. It defines and exposes radio and network information to facilitate the management and maintenance of a mobile Wireless LAN.
IEEE 802.11k and 802.11r are the key industry standards now in development that will enable seamless Basic Service Set (BSS) transitions in the WLAN environment. The 802.11k standard provides information to discover the best available access point.
802.11k is intended to improve the way traffic is distributed within a network. In a wireless LAN, each device normally connects to the access point (AP) that provides the strongest signal. Depending on the number and geographic locations of the subscribers, this arrangement can sometimes lead to excessive demand on one AP and underutilization of others, resulting in degradation of overall network performance. In a network conforming to 802.11k, if the AP having the strongest signal is loaded to its full capacity, a wireless device is connected to one of the underutilized APs. Even though the signal may be weaker, the overall throughput is greater because more efficient use is made of the network resources
IEEE 802.11k and 802.11r are the key industry standards now in development that will enable seamless Basic Service Set (BSS) transitions in the WLAN environment. The 802.11k standard provides information to discover the best available access point.
802.11k is intended to improve the way traffic is distributed within a network. In a wireless LAN, each device normally connects to the access point (AP) that provides the strongest signal. Depending on the number and geographic locations of the subscribers, this arrangement can sometimes lead to excessive demand on one AP and underutilization of others, resulting in degradation of overall network performance. In a network conforming to 802.11k, if the AP having the strongest signal is loaded to its full capacity, a wireless device is connected to one of the underutilized APs. Even though the signal may be weaker, the overall throughput is greater because more efficient use is made of the network resources
IEEE 802.11j-2004
802.11j-2004 or 802.11j is an amendment to the IEEE 802.11 standard designed specially for Japanese market. It allows Wireless LAN operation in the 4.9 to 5 GHz band to conform to the Japanese rules for radio operation for indoor, outdoor and mobile applications. The amendment has been incorporated into the published IEEE 802.11-2007 standard.
802.11 is a set of IEEE standards that govern wireless networking transmission methods. They are commonly used today in their 802.11a, 802.11b, and 802.11g versions to provide wireless connectivity in the home, office and some commercial establishments.
802.11 is a set of IEEE standards that govern wireless networking transmission methods. They are commonly used today in their 802.11a, 802.11b, and 802.11g versions to provide wireless connectivity in the home, office and some commercial establishments.
IEEE 802.11w
IEEE 802.11w is a proposed amendment to the IEEE 802.11 standard to increase the security of its management frames.
802.11 is a set of IEEE standards that govern wireless networking transmission methods. They are commonly used today in their 802.11a, 802.11b, and 802.11g versions to provide wireless connectivity in the home, office and some commercial establishments.
Current 802.11x standards define "frame" types for use in management and control of wireless links. IEEE 802.11w is the Protected Management Frames standard for the IEEE 802.11 family of standards. TGw is working on improving the IEEE 802.11 Medium Access Control layer. The objective of this is to increase the security by providing data confidentiality of management frames, mechanisms that enable data integrity, data origin authenticity, and replay protection. These extensions will have interactions with IEEE 802.11r and IEEE 802.11u
Wireless LANs send system management information in unprotected frames, which makes them vulnerable. This standard will protect against network disruption caused by malicious systems that forge disassociation requests that appear to be sent by valid equipment
802.11 is a set of IEEE standards that govern wireless networking transmission methods. They are commonly used today in their 802.11a, 802.11b, and 802.11g versions to provide wireless connectivity in the home, office and some commercial establishments.
Current 802.11x standards define "frame" types for use in management and control of wireless links. IEEE 802.11w is the Protected Management Frames standard for the IEEE 802.11 family of standards. TGw is working on improving the IEEE 802.11 Medium Access Control layer. The objective of this is to increase the security by providing data confidentiality of management frames, mechanisms that enable data integrity, data origin authenticity, and replay protection. These extensions will have interactions with IEEE 802.11r and IEEE 802.11u
Wireless LANs send system management information in unprotected frames, which makes them vulnerable. This standard will protect against network disruption caused by malicious systems that forge disassociation requests that appear to be sent by valid equipment
Wi-Fi
Wi-Fi (pronounced /ˈwaɪfaɪ/) is a trademark of the Wi-Fi Alliance for certified products based on the IEEE 802.11 standards. This certification warrants interoperability between different wireless devices.
The term Wi-Fi is often used by the public as a synonym for wireless LAN (WLAN); but not every wireless LAN product has a Wi-Fi certification, which may be because of certification costs that must be paid for each certified device type.
Wi-Fi is supported by most personal computer operating systems, many game consoles, laptops, smartphones, printers, and other peripherals.
Spectrum assignments and operational limitations are not consistent worldwide. Most of Europe allows for an additional 2 channels beyond those permitted in the U.S. for the 2.4 GHz band. (1–13 vs. 1–11); Japan has one more on top of that (1–14). Europe, as of 2007, was essentially homogeneous in this respect. A very confusing aspect is the fact that a Wi-Fi signal actually occupies five channels in the 2.4 GHz band resulting in only three non-overlapped channels in the U.S.: 1, 6, 11, and three or four in Europe: 1, 5, 9, 13 can be used if all the equipment on a specific area can be guaranteed not to use 802.11b at all, even as fallback or beacon. Equivalent isotropically radiated power (EIRP) in the EU is limited to 20 dBm
The term Wi-Fi is often used by the public as a synonym for wireless LAN (WLAN); but not every wireless LAN product has a Wi-Fi certification, which may be because of certification costs that must be paid for each certified device type.
Wi-Fi is supported by most personal computer operating systems, many game consoles, laptops, smartphones, printers, and other peripherals.
Spectrum assignments and operational limitations are not consistent worldwide. Most of Europe allows for an additional 2 channels beyond those permitted in the U.S. for the 2.4 GHz band. (1–13 vs. 1–11); Japan has one more on top of that (1–14). Europe, as of 2007, was essentially homogeneous in this respect. A very confusing aspect is the fact that a Wi-Fi signal actually occupies five channels in the 2.4 GHz band resulting in only three non-overlapped channels in the U.S.: 1, 6, 11, and three or four in Europe: 1, 5, 9, 13 can be used if all the equipment on a specific area can be guaranteed not to use 802.11b at all, even as fallback or beacon. Equivalent isotropically radiated power (EIRP) in the EU is limited to 20 dBm
IEEE 802.11r
IEEE 802.11r-2008 or fast BSS transition (FT) is an amendment to the IEEE 802.11 standard to permit continuous connectivity aboard wireless devices in motion, with fast and secure handoffs from one base station to another managed in a seamless manner.
802.11, commonly referred to as Wi-Fi, is widely used for wireless communications. Many deployed implementations have effective ranges of only a few hundred meters, so to maintain communications devices in motion that use it will need to handoff from one access point to another. In an automotive environment, this could easily result in a handoff every five to ten seconds.
Handoffs are already supported under the preexisting standard. The fundamental architecture for handoffs is identical for 802.11 with and without 802.11r: the mobile device is entirely in charge of deciding when to hand off and to which access point it wishes to hand off. In the early days of 802.11, handoff was a much simpler task for the mobile device. Only four messages were required for the device to establish a connection with a new access point (five if you count the optional message the client could send to the old access point to inform it that it had left). However, as additional features were added to the standard, including 802.11i with 802.1X authentication and 802.11e or WMM with admission control requests, the number of messages required went up dramatically. During the time these additional messages are being exchanged, the mobile device's traffic, including that from voice calls, cannot proceed, and the user will hear loss approaching that of seconds.[1] Generally, the highest amount of delay or loss that the edge network should introduce into a voice call is 50 msec.
802.11r was launched to attempt to undo the added burden that security and quality of service added to the handoff process, and restore it back to the original four-message exchange. In this way, handoff problems are not eliminated, but at least are returned to the status quo.
The primary application currently envisioned for the 802.11r standard is VOIP ("voice over IP", or Internet-based telephony) via mobile phones designed to work with wireless Internet networks, instead of (or in addition to) standard cellular networks.
802.11, commonly referred to as Wi-Fi, is widely used for wireless communications. Many deployed implementations have effective ranges of only a few hundred meters, so to maintain communications devices in motion that use it will need to handoff from one access point to another. In an automotive environment, this could easily result in a handoff every five to ten seconds.
Handoffs are already supported under the preexisting standard. The fundamental architecture for handoffs is identical for 802.11 with and without 802.11r: the mobile device is entirely in charge of deciding when to hand off and to which access point it wishes to hand off. In the early days of 802.11, handoff was a much simpler task for the mobile device. Only four messages were required for the device to establish a connection with a new access point (five if you count the optional message the client could send to the old access point to inform it that it had left). However, as additional features were added to the standard, including 802.11i with 802.1X authentication and 802.11e or WMM with admission control requests, the number of messages required went up dramatically. During the time these additional messages are being exchanged, the mobile device's traffic, including that from voice calls, cannot proceed, and the user will hear loss approaching that of seconds.[1] Generally, the highest amount of delay or loss that the edge network should introduce into a voice call is 50 msec.
802.11r was launched to attempt to undo the added burden that security and quality of service added to the handoff process, and restore it back to the original four-message exchange. In this way, handoff problems are not eliminated, but at least are returned to the status quo.
The primary application currently envisioned for the 802.11r standard is VOIP ("voice over IP", or Internet-based telephony) via mobile phones designed to work with wireless Internet networks, instead of (or in addition to) standard cellular networks.
Inter-Access Point Protocol
IEEE 802.11F or Inter-Access Point Protocol is a recommendation that describes an optional extension to IEEE 802.11 that provides wireless access-point communications among multivendor systems . 802.11 is a set of IEEE standards that govern wireless networking transmission methods. They are commonly used today in their 802.11a, 802.11b, 802.11g and 802.11n versions to provide wireless connectivity in the home, office and some commercial establishments.
The IEEE 802.11 standard doesn't specify the communications between access points in order to support users roaming from one access point to another and load balancing. The 802.11 WG purposely didn't define this element in order to provide flexibility in working with different wired and wireless distribution systems (i.e., wired backbones that interconnect access points).
The IEEE 802.11 standard doesn't specify the communications between access points in order to support users roaming from one access point to another and load balancing. The 802.11 WG purposely didn't define this element in order to provide flexibility in working with different wired and wireless distribution systems (i.e., wired backbones that interconnect access points).
Channels and international compatibility
802.11 divides each of the above-described bands into channels, analogously to how radio and TV broadcast bands are carved up but with greater channel width and overlap. For example the 2.4000–2.4835 GHz band is divided into 13 channels each of width 22 MHz but spaced only 5 MHz apart, with channel 1 centred on 2.412 GHz and 13 on 2.472 GHz to which Japan adds a 14th channel 12 MHz above channel 13.
Availability of channels is regulated by country, constrained in part by how each country allocates radio spectrum to various services. At one extreme Japan permits the use of all 14 channels (with the exclusion of 802.11g/n from channel 14), while at the other Spain allowed only channels 10 and 11 (later all of the 14 channels have been allowed,and France that allowed only 10, 11, 12 and 13 (now channels 1 to 13 are allowed). Most other European countries are almost as liberal as Japan, disallowing only channel 14, while North America and some Central and South American countries further disallow 12 and 13. For more details on this topic, see List of WLAN channels.
Besides specifying the centre frequency of each channel, 802.11 also specifies (in Clause 17) a spectral mask defining the permitted distribution of power across each channel. The mask requires that the signal be attenuated by at least 30 dB from its peak energy at ±11 MHz from the centre frequency, the sense in which channels are effectively 22 MHz wide. One consequence is that stations can only use every fourth or fifth channel without overlap, typically 1, 6 and 11 in the Americas, 1, 5, 9 and 13 in Europe, etc. Another is that channels 1-13 effectively require the band 2.401–2.483 GHz, the actual allocations being, for example, 2.400–2.4835 GHz in the UK, 2.402–2.4835 GHz in the US, etc.
Since the spectral mask only defines power output restrictions up to ±22 MHz from the center frequency to be attenuated by 50 dB, it is often assumed that the energy of the channel extends no further than these limits. It is more correct to say that, given the separation between channels 1, 6, and 11, the signal on any channel should be sufficiently attenuated to minimally interfere with a transmitter on any other channel. Due to the near-far problem a transmitter can impact a receiver on a "non-overlapping" channel, but only if it is close to the victim receiver (within a meter) or operating above allowed power levels.
Although the statement that channels 1, 6, and 11 are "non-overlapping" is limited to spacing or product density, the 1–6–11 guideline has merit. If transmitters are closer together than channels 1, 6, and 11 (for example, 1, 4, 7, and 10), overlap between the channels may cause unacceptable degradation of signal quality and throughput.[11] However, overlapping channels may be used under certain circumstances. This way, more channels are available
Availability of channels is regulated by country, constrained in part by how each country allocates radio spectrum to various services. At one extreme Japan permits the use of all 14 channels (with the exclusion of 802.11g/n from channel 14), while at the other Spain allowed only channels 10 and 11 (later all of the 14 channels have been allowed,and France that allowed only 10, 11, 12 and 13 (now channels 1 to 13 are allowed). Most other European countries are almost as liberal as Japan, disallowing only channel 14, while North America and some Central and South American countries further disallow 12 and 13. For more details on this topic, see List of WLAN channels.
Besides specifying the centre frequency of each channel, 802.11 also specifies (in Clause 17) a spectral mask defining the permitted distribution of power across each channel. The mask requires that the signal be attenuated by at least 30 dB from its peak energy at ±11 MHz from the centre frequency, the sense in which channels are effectively 22 MHz wide. One consequence is that stations can only use every fourth or fifth channel without overlap, typically 1, 6 and 11 in the Americas, 1, 5, 9 and 13 in Europe, etc. Another is that channels 1-13 effectively require the band 2.401–2.483 GHz, the actual allocations being, for example, 2.400–2.4835 GHz in the UK, 2.402–2.4835 GHz in the US, etc.
Since the spectral mask only defines power output restrictions up to ±22 MHz from the center frequency to be attenuated by 50 dB, it is often assumed that the energy of the channel extends no further than these limits. It is more correct to say that, given the separation between channels 1, 6, and 11, the signal on any channel should be sufficiently attenuated to minimally interfere with a transmitter on any other channel. Due to the near-far problem a transmitter can impact a receiver on a "non-overlapping" channel, but only if it is close to the victim receiver (within a meter) or operating above allowed power levels.
Although the statement that channels 1, 6, and 11 are "non-overlapping" is limited to spacing or product density, the 1–6–11 guideline has merit. If transmitters are closer together than channels 1, 6, and 11 (for example, 1, 4, 7, and 10), overlap between the channels may cause unacceptable degradation of signal quality and throughput.[11] However, overlapping channels may be used under certain circumstances. This way, more channels are available
IEEE 802.11y
IEEE 802.11y-2008 is an amendment to the IEEE 802.11-2007 standard that will enable high powered Wi-Fi equipment to operate on a co-primary basis in the 3650 to 3700 MHz band in the United States, except when near a grandfathered satellite earth station. It was approved for publication by the IEEE on September 26, 2008.
The US 3650 MHz rules allow for registered stations to operate at much higher power than traditional Wi-Fi gear (Up to 20 watts equivalent isotropically radiated power). The combination of higher power limits and enhancements made to the MAC timing in 802.11-2007, will allow for the development of standards based 802.11 devices that could operate at distances of 5 kilometres (3 mi) or more.
IEEE 802.11y adds three new concepts to 802.11-2007 base Standard:
Contention based protocol (CBP)- enhancements have been made to the carrier sensing and energy detection mechanisms of 802.11 in order to meet the FCC's requirements for a contention based protocol.
Extended channel switch announcement (ECSA)- provides a mechanism for an access point to notify the stations connected to it of its intention to change channels or to change channel bandwidth. This mechanism will allow for the WLAN to continuously choose the channel that is the least noisy and the least likely to cause interference. ECSA also provides for other functionalities besides dynamic channel selection based on quality & noise characteristics.
For instance, in 802.11y Amendment, the licensed operator can send ECSA commands to any stations operating under their control, registered or unregistered. ECSA is also used in 802.11n. In the 802.11n D2.0 implementation (which is shipping & undergoes Wi-Fi Alliance testing) 20MHz & 40MHz channel switching is provided for by the 11n PHY's ECSA implementation. Note that 802.11n is specified for operation in the 2.4GHz and 5GHz license exempt bands--but future amendments could permit 11n's PHY to operate in other bands as well.
Dependent station enablement (DSE)- is the mechanism by which an operator extends and retracts permission to license exempt devices (referred to as dependent STAs in .11y) to use licensed radio spectrum. Fundamentally, this process satisfies a regulatory requirement that dictates that a dependent STAs operation is contingent upon its ability to receive periodic messages from a licensees base station, but DSE is extensible to other purposes in regards to channel management and coordination.
The US 3650 MHz rules allow for registered stations to operate at much higher power than traditional Wi-Fi gear (Up to 20 watts equivalent isotropically radiated power). The combination of higher power limits and enhancements made to the MAC timing in 802.11-2007, will allow for the development of standards based 802.11 devices that could operate at distances of 5 kilometres (3 mi) or more.
IEEE 802.11y adds three new concepts to 802.11-2007 base Standard:
Contention based protocol (CBP)- enhancements have been made to the carrier sensing and energy detection mechanisms of 802.11 in order to meet the FCC's requirements for a contention based protocol.
Extended channel switch announcement (ECSA)- provides a mechanism for an access point to notify the stations connected to it of its intention to change channels or to change channel bandwidth. This mechanism will allow for the WLAN to continuously choose the channel that is the least noisy and the least likely to cause interference. ECSA also provides for other functionalities besides dynamic channel selection based on quality & noise characteristics.
For instance, in 802.11y Amendment, the licensed operator can send ECSA commands to any stations operating under their control, registered or unregistered. ECSA is also used in 802.11n. In the 802.11n D2.0 implementation (which is shipping & undergoes Wi-Fi Alliance testing) 20MHz & 40MHz channel switching is provided for by the 11n PHY's ECSA implementation. Note that 802.11n is specified for operation in the 2.4GHz and 5GHz license exempt bands--but future amendments could permit 11n's PHY to operate in other bands as well.
Dependent station enablement (DSE)- is the mechanism by which an operator extends and retracts permission to license exempt devices (referred to as dependent STAs in .11y) to use licensed radio spectrum. Fundamentally, this process satisfies a regulatory requirement that dictates that a dependent STAs operation is contingent upon its ability to receive periodic messages from a licensees base station, but DSE is extensible to other purposes in regards to channel management and coordination.
IEEE 802.11k-2008
IEEE 802.11k-2008 is an amendment to IEEE 802.11-2007 standard for radio resource management. It defines and exposes radio and network information to facilitate the management and maintenance of a mobile Wireless LAN.
IEEE 802.11k and 802.11r are the key industry standards now in development that will enable seamless Basic Service Set (BSS) transitions in the WLAN environment. The 802.11k standard provides information to discover the best available access point.
802.11k is intended to improve the way traffic is distributed within a network. In a wireless LAN, each device normally connects to the access point (AP) that provides the strongest signal. Depending on the number and geographic locations of the subscribers, this arrangement can sometimes lead to excessive demand on one AP and underutilization of others, resulting in degradation of overall network performance. In a network conforming to 802.11k, if the AP having the strongest signal is loaded to its full capacity, a wireless device is connected to one of the underutilized APs. Even though the signal may be weaker, the overall throughput is greater because more efficient use is made of the network resources.
IEEE 802.11k and 802.11r are the key industry standards now in development that will enable seamless Basic Service Set (BSS) transitions in the WLAN environment. The 802.11k standard provides information to discover the best available access point.
802.11k is intended to improve the way traffic is distributed within a network. In a wireless LAN, each device normally connects to the access point (AP) that provides the strongest signal. Depending on the number and geographic locations of the subscribers, this arrangement can sometimes lead to excessive demand on one AP and underutilization of others, resulting in degradation of overall network performance. In a network conforming to 802.11k, if the AP having the strongest signal is loaded to its full capacity, a wireless device is connected to one of the underutilized APs. Even though the signal may be weaker, the overall throughput is greater because more efficient use is made of the network resources.
IEEE 802.11v
802.11v is the Wireless Network Management standard for the IEEE 802.11 family of standards. TGv is working on an amendment to the 802.11 standard to allow configuration of client devices while connected to IEEE 802.11 networks. The standard may include cellular-like management paradigms
IEEE 802.11p
IEEE 802.11p is a draft amendment to the IEEE 802.11 standard to add wireless access in vehicular environments (WAVE). It defines enhancements to 802.11 required to support Intelligent Transportation Systems (ITS) applications. This includes data exchange between high-speed vehicles and between the vehicles and the roadside infrastructure in the licensed ITS band of 5.9 GHz (5.85-5.925 GHz). IEEE 1609 is a higher layer standard on which IEEE 802.11p is based.
802.11p will be used as the groundwork for Dedicated Short Range Communications (DSRC), a U.S. Department of Transportation project based on the ISO Communications, Air-interface, Long and Medium range (CALM) architecture standard looking at vehicle-based communication networks, particularly for applications such as toll collection, vehicle safety services, and commerce transactions via cars. The ultimate vision is a nationwide network that enables communications between vehicles and roadside access points or other vehicles. This work builds on its predecessor ASTM E2213-03.
802.11p will be used as the groundwork for Dedicated Short Range Communications (DSRC), a U.S. Department of Transportation project based on the ISO Communications, Air-interface, Long and Medium range (CALM) architecture standard looking at vehicle-based communication networks, particularly for applications such as toll collection, vehicle safety services, and commerce transactions via cars. The ultimate vision is a nationwide network that enables communications between vehicles and roadside access points or other vehicles. This work builds on its predecessor ASTM E2213-03.
IEEE 802.11u
IEEE 802.11u is a proposed amendment to the IEEE 802.11-2007 standard to add features that improve interworking with external networks.
802.11 is an IEEE standard that allows devices such as laptop computers or cellular phones to join a wireless LAN widely used in the home, office and some commercial establishments.
IEEE 802.11 currently makes an assumption that a user is pre-authorised to use the network. IEEE 802.11u covers the cases where user is not pre-authorised. A network will be able to allow access based on the user's relationship with an external network (e.g. hotspot roaming agreements), or indicate that online enrollment is possible, or allow access to a strictly limited set of services such as emergency services (client to authority and authority to client.)
From a user perspective, the aim is to improve the experience of a traveling user who turns on a laptop in a hotel many miles from home. Instead of being presented with a long list of largely meaningless SSIDs the user could be presented with a list of networks, the services they provide, and the conditions under which the user could access them.
The IEEE 802.11u Proposal Requirements Specification contains requirements in the areas of enrollment, network selection, emergency call support, emergency alert notification, user traffic segmentation, and service advertisement.
802.11 is an IEEE standard that allows devices such as laptop computers or cellular phones to join a wireless LAN widely used in the home, office and some commercial establishments.
IEEE 802.11 currently makes an assumption that a user is pre-authorised to use the network. IEEE 802.11u covers the cases where user is not pre-authorised. A network will be able to allow access based on the user's relationship with an external network (e.g. hotspot roaming agreements), or indicate that online enrollment is possible, or allow access to a strictly limited set of services such as emergency services (client to authority and authority to client.)
From a user perspective, the aim is to improve the experience of a traveling user who turns on a laptop in a hotel many miles from home. Instead of being presented with a long list of largely meaningless SSIDs the user could be presented with a list of networks, the services they provide, and the conditions under which the user could access them.
The IEEE 802.11u Proposal Requirements Specification contains requirements in the areas of enrollment, network selection, emergency call support, emergency alert notification, user traffic segmentation, and service advertisement.
802.11T puts WLANs to the test
Buyers of Wi-Fi equipment and systems must be assured that all products have the performance and stability to carry mission-critical applications and data. However, testing of Wi-Fi, or 802.11, devices and systems for performance and stability is a challenge for the industry because of the complexity of the 802.11 protocol. That is compounded by the inherent mobility of the wireless devices and the prevalence of radio frequency interference
802.11n
802.11n is a proposed amendment which improves upon the previous 802.11 standards by adding multiple-input multiple-output (MIMO) and many other newer features. The TGn workgroup is not expected to finalize the amendment until December 2009.[6] Enterprises, however, have already begun migrating to 802.11n networks based on Draft 2 of the 802.11n proposal. A common strategy for many businesses is to set up 802.11b and 802.11g client devices while gradually moving to 802.11n clients as part of new equipment purchases
802.11g
In June 2003, a third modulation standard was ratified: 802.11g. This works in the 2.4 GHz band (like 802.11b), but uses the same OFDM based transmission scheme as 802.11a. It operates at a maximum physical layer bit rate of 54 Mbit/s exclusive of forward error correction codes, or about 19 Mbit/s average throughput[citation needed]. 802.11g hardware is fully backwards compatible with 802.11b hardware and therefore is encumbered with legacy issues that reduce throughput when compared to 802.11a by ~21%.
The then-proposed 802.11g standard was rapidly adopted by consumers starting in January 2003, well before ratification, due to the desire for higher data rates, and reductions in manufacturing costs. By summer 2003, most dual-band 802.11a/b products became dual-band/tri-mode, supporting a and b/g in a single mobile adapter card or access point. Details of making b and g work well together occupied much of the lingering technical process; in an 802.11g network, however, activity by a 802.11b participant will reduce the data rate of the overall 802.11g network.
Like 802.11b, 802.11g devices suffer interference from other products operating in the 2.4 GHz band
The then-proposed 802.11g standard was rapidly adopted by consumers starting in January 2003, well before ratification, due to the desire for higher data rates, and reductions in manufacturing costs. By summer 2003, most dual-band 802.11a/b products became dual-band/tri-mode, supporting a and b/g in a single mobile adapter card or access point. Details of making b and g work well together occupied much of the lingering technical process; in an 802.11g network, however, activity by a 802.11b participant will reduce the data rate of the overall 802.11g network.
Like 802.11b, 802.11g devices suffer interference from other products operating in the 2.4 GHz band
802.11b
Release date Frequency band Throughput (typ.) Net bit rate (max.) Range (indoor)
October 1999 2.4 GHz ~5 Mbit/s[4] 11 Mbit/s ~30 m[citation needed]
Main article: IEEE 802.11b-1999
802.11b has a maximum raw data rate of 11 Mbit/s and uses the same media access method defined in the original standard. 802.11b products appeared on the market in early 2000, since 802.11b is a direct extension of the modulation technique defined in the original standard. The dramatic increase in throughput of 802.11b (compared to the original standard) along with simultaneous substantial price reductions led to the rapid acceptance of 802.11b as the definitive wireless LAN technology.
802.11b devices suffer interference from other products operating in the 2.4 GHz band. Devices operating in the 2.4 GHz range include: microwave ovens, Bluetooth devices, baby monitors and cordless telephones.
October 1999 2.4 GHz ~5 Mbit/s[4] 11 Mbit/s ~30 m[citation needed]
Main article: IEEE 802.11b-1999
802.11b has a maximum raw data rate of 11 Mbit/s and uses the same media access method defined in the original standard. 802.11b products appeared on the market in early 2000, since 802.11b is a direct extension of the modulation technique defined in the original standard. The dramatic increase in throughput of 802.11b (compared to the original standard) along with simultaneous substantial price reductions led to the rapid acceptance of 802.11b as the definitive wireless LAN technology.
802.11b devices suffer interference from other products operating in the 2.4 GHz band. Devices operating in the 2.4 GHz range include: microwave ovens, Bluetooth devices, baby monitors and cordless telephones.
802.11a
Release date Op. Frequency Throughput (typ.) Net bit rate (max.) Gross bit rate (max.) Range (indoor)
October 1999 5 GHz 27 Mbit/s[4] 54 Mbit/s 72 Mbit/s ~35 m[citation needed]
Main article: IEEE 802.11a-1999
The 802.11a standard uses the same data link layer protocol and frame format as the original standard, but an OFDM based air interface (physical layer). It operates in the 5 GHz band with a maximum net data rate of 54 Mbit/s, plus error correction code, which yields realistic net achievable throughput in the mid-20 Mbit/s[citation needed].
Since the 2.4 GHz band is heavily used to the point of being crowded, using the relatively un-used 5 GHz band gives 802.11a a significant advantage. However, this high carrier frequency also brings a disadvantage: The effective overall range of 802.11a is less than that of 802.11b/g; and in theory 802.11a signals cannot penetrate as far as those for 802.11b because they are absorbed more readily by walls and other solid objects in their path due to their smaller wavelength. In practice 802.11b typically has a higher distance range at low speeds (802.11b will reduce speed to 5 Mbit/s or even 1 Mbit/s at low signal strengths). However, at higher speeds, 802.11a typically has the same or higher range due to less interference
October 1999 5 GHz 27 Mbit/s[4] 54 Mbit/s 72 Mbit/s ~35 m[citation needed]
Main article: IEEE 802.11a-1999
The 802.11a standard uses the same data link layer protocol and frame format as the original standard, but an OFDM based air interface (physical layer). It operates in the 5 GHz band with a maximum net data rate of 54 Mbit/s, plus error correction code, which yields realistic net achievable throughput in the mid-20 Mbit/s[citation needed].
Since the 2.4 GHz band is heavily used to the point of being crowded, using the relatively un-used 5 GHz band gives 802.11a a significant advantage. However, this high carrier frequency also brings a disadvantage: The effective overall range of 802.11a is less than that of 802.11b/g; and in theory 802.11a signals cannot penetrate as far as those for 802.11b because they are absorbed more readily by walls and other solid objects in their path due to their smaller wavelength. In practice 802.11b typically has a higher distance range at low speeds (802.11b will reduce speed to 5 Mbit/s or even 1 Mbit/s at low signal strengths). However, at higher speeds, 802.11a typically has the same or higher range due to less interference
IEEE 802.11
IEEE 802.11 is a set of standards carrying out wireless local area network (WLAN) computer communication in the 2.4, 3.6 and 5 GHz frequency bands. They are implemented by the IEEE LAN/MAN Standards Committee (IEEE 802).
The original version of the standard IEEE 802.11 was released in 1997 and clarified in 1999, but is today obsolete. It specified two net bit rates of 1 or 2 megabits per second (Mbit/s), plus forward error correction code. It specifed three alternative physical layer technologies: diffuse infrared operating at 1 Mbit/s; frequency-hopping spread spectrum operating at 1 Mbit/s or 2 Mbit/s; and direct-sequence spread spectrum operating at 1 Mbit/s or 2 Mbit/s. The latter two radio technologies used microwave transmission over the Industrial Scientific Medical frequency band at 2.4 GHz. Some earlier WLAN technologies used lower frequencies, such as the U.S. 900 MHz ISM band.
Legacy 802.11 with direct-sequence spread spectrum was rapidly supplemented and popularized by 802.11b.
The original version of the standard IEEE 802.11 was released in 1997 and clarified in 1999, but is today obsolete. It specified two net bit rates of 1 or 2 megabits per second (Mbit/s), plus forward error correction code. It specifed three alternative physical layer technologies: diffuse infrared operating at 1 Mbit/s; frequency-hopping spread spectrum operating at 1 Mbit/s or 2 Mbit/s; and direct-sequence spread spectrum operating at 1 Mbit/s or 2 Mbit/s. The latter two radio technologies used microwave transmission over the Industrial Scientific Medical frequency band at 2.4 GHz. Some earlier WLAN technologies used lower frequencies, such as the U.S. 900 MHz ISM band.
Legacy 802.11 with direct-sequence spread spectrum was rapidly supplemented and popularized by 802.11b.
Tuesday, May 5, 2009
Tuesday, April 21, 2009
Thursday, April 16, 2009
Monday, April 13, 2009
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Technical features of WCDMA
^ Radio channels are 5MHz wide.
^ Chip rate of 3.84 Mcps
^ Supports two basic modes of duplex: frequency division and time division. Current systems use frequency division, one frequency for uplink and one for downlink. For time division, FOMA uses sixteen slots per radio frame, whereas UMTS uses fifteen slots per radio frame.
^ Employs coherent detection on both the uplink and downlink based on the use of pilot symbols and channels.
^ Supports inter-cell asynchronous operation.
^ Variable mission on a 10 ms frame basis.
^ Multicode transmission.
^ Adaptive power control based on SIR (Signal-to-Interference Ratio).
^ Multiuser detection and smart antennas can be used to increase capacity and coverage.
^ Multiple types of handoff (or handover) between different cells including soft handoff, softer handoff and hard handoff.
^ Chip rate of 3.84 Mcps
^ Supports two basic modes of duplex: frequency division and time division. Current systems use frequency division, one frequency for uplink and one for downlink. For time division, FOMA uses sixteen slots per radio frame, whereas UMTS uses fifteen slots per radio frame.
^ Employs coherent detection on both the uplink and downlink based on the use of pilot symbols and channels.
^ Supports inter-cell asynchronous operation.
^ Variable mission on a 10 ms frame basis.
^ Multicode transmission.
^ Adaptive power control based on SIR (Signal-to-Interference Ratio).
^ Multiuser detection and smart antennas can be used to increase capacity and coverage.
^ Multiple types of handoff (or handover) between different cells including soft handoff, softer handoff and hard handoff.
Rationale for W-CDMA
W-CDMA transmits on a pair of 5 MHz-wide radio channels, while CDMA2000 transmits on one or several pairs of 1.25 MHz radio channels. Though W-CDMA does use a direct sequence CDMA transmission technique like CDMA2000, W-CDMA is not simply a wideband version of CDMA2000. The W-CDMA system is a new design by NTT DoCoMo, and it differs in many aspects from CDMA2000. From an engineering point of view, W-CDMA provides a different balance of trade-offs between cost, capacity, performance, and density; it also promises to achieve a benefit of reduced cost for video phone handsets. W-CDMA may also be better suited for deployment in the very dense cities of Europe and Asia. However, hurdles remain, and cross-licencing of patents between Qualcomm and W-CDMA vendors has not eliminated possible patent issues due to the features of W-CDMA which remain covered by Qualcomm patents.
W-CDMA has been developed into a complete set of specifications, a detailed protocol that defines how a mobile phone communicates with the tower, how signals are modulated, how datagrams are structured, and system interfaces are specified allowing free competition on technology elements.
W-CDMA has been developed into a complete set of specifications, a detailed protocol that defines how a mobile phone communicates with the tower, how signals are modulated, how datagrams are structured, and system interfaces are specified allowing free competition on technology elements.
Development in WCDMA
W-CDMA was developed by NTT DoCoMo as the air interface for their 3G network FOMA. Later NTT DoCoMo submitted the specification to the International Telecommunication Union (ITU) as a candidate for the international 3G standard known as IMT-2000. The ITU eventually accepted W-CDMA as part of the IMT-2000 family of 3G standards, as an alternative to CDMA2000, EDGE, and the short range DECT system. Later, W-CDMA was selected as the air interface for UMTS, the 3G successor to GSM.
Code Division Multiple Access communication networks have been developed by a number of companies over the years, but development of cell-phone networks based on CDMA (prior to W-CDMA) was dominated by Qualcomm, the first company to succeed in developing a practical and cost-effective CDMA implementation for consumer cell phones, its early IS-95 air interface standard. IS-95 evolved into the current CDMA2000 (IS-856/IS-2000) standard.
In the late 1990s, NTT DoCoMo began work on a new wide-band CDMA air interface for their planned 3G network FOMA. FOMA's air interface, called W-CDMA, was selected as the air interface for UMTS, a newer W-CDMA based system designed to be an easier upgrade for European GSM networks compared to FOMA. FOMA and UMTS use essentially the same air interface, but are different in other ways; thus, handsets are not 100% compatible between FOMA and UMTS, but roaming is supported.
Qualcomm created an experimental wideband CDMA system called CDMA2000 3x which unified the W-CDMA (3GPP) and CDMA2000 (3GPP2) network technologies into a single design for a worldwide standard air interface. Compatibility with CDMA2000 would have beneficially enabled roaming on existing networks beyond Japan, since Qualcomm CDMA2000 networks are widely deployed, especially in the Americas, with coverage in 58 countries as of 2006[update]. However, divergent requirements resulted in the W-CDMA standard being retained and deployed.
Despite incompatibilities with existing air-interface standards, the late introduction of this 3G system, and despite the high upgrade cost of deploying an all-new transmitter technology, W-CDMA has been adopted and deployed rapidly, especially in Japan, Europe and Asia, and is already deployed in over 55 countries as of 2006[update].
Code Division Multiple Access communication networks have been developed by a number of companies over the years, but development of cell-phone networks based on CDMA (prior to W-CDMA) was dominated by Qualcomm, the first company to succeed in developing a practical and cost-effective CDMA implementation for consumer cell phones, its early IS-95 air interface standard. IS-95 evolved into the current CDMA2000 (IS-856/IS-2000) standard.
In the late 1990s, NTT DoCoMo began work on a new wide-band CDMA air interface for their planned 3G network FOMA. FOMA's air interface, called W-CDMA, was selected as the air interface for UMTS, a newer W-CDMA based system designed to be an easier upgrade for European GSM networks compared to FOMA. FOMA and UMTS use essentially the same air interface, but are different in other ways; thus, handsets are not 100% compatible between FOMA and UMTS, but roaming is supported.
Qualcomm created an experimental wideband CDMA system called CDMA2000 3x which unified the W-CDMA (3GPP) and CDMA2000 (3GPP2) network technologies into a single design for a worldwide standard air interface. Compatibility with CDMA2000 would have beneficially enabled roaming on existing networks beyond Japan, since Qualcomm CDMA2000 networks are widely deployed, especially in the Americas, with coverage in 58 countries as of 2006[update]. However, divergent requirements resulted in the W-CDMA standard being retained and deployed.
Despite incompatibilities with existing air-interface standards, the late introduction of this 3G system, and despite the high upgrade cost of deploying an all-new transmitter technology, W-CDMA has been adopted and deployed rapidly, especially in Japan, Europe and Asia, and is already deployed in over 55 countries as of 2006[update].
Who benefits if W-CDMA Wins
AT&T Mobility and Verizon Wireless , the two largest U.S. carriers, would like to see W-CDMA win. AT&T Mobility is uniquely positioned in the U.S. as the largest UMTS (based on W-CDMA) network, and Verizon Wireless is on a CDMA2000 network, whose broadband evolution is more likely to tap into WCDMA than WiMax. and as well as all other 3G wireless broadband providers, are deeply concerned about who wins the WiMax/W-CDMA battle. wants to see W-CDMA prevail and eventually move into the HSPA/LTE generation. Sprint Nextel (S), while running a CDMA2000/EV-DO network, has committed to offering a 4G WiMax Network in a partnership with Intel (INTC) Motorola (MOT), and Samsung.
Cable (e.g. Comcast (CMCSA) and Time Warner Cable, DSL (e.g. Qwest Communications International (Q), and Wireless Internet Service Providers (WISPs) who sell access to hot spots (e.g. EarthLink (ELNK) all stand to lose business with the success of WiMax, a clear technology substitue. However, this is similarly true with the success of W-CDMA, as long as wireless 3G carriers offer price competition to the "always-on broadband" currently offered by Cable and DSL providers. This is unlikely in the short run, however, because wireless carriers have made a mint in per-minute billing and won't move to flat-rate unless they have to. Thus, they'd prefer to see W-CDMA and voice-based technology win the race.
Alcatel (ALU), Nokia (NOK), and Motorola (MOT) three large wireless equipment vendors that have all moved through the wireless evolution with carriers. They're better poised for W-CDMA to win, but have all agreed to offer WiMax functionality in future products. They are clearly hedging their bets here.
AOL and other Internet service providers offering dial-up Internet connectivity have already seen their businesses decline, and the competition between W-CDMA and WiMax will further put downward pressure on broadband Internet access subscription fees, which will further drive people away from dial-up. WiMax, however, is more of a threat because those who use dial-up are more likely not to need mobile broadband access, and WiMax is gaining the most traction these days in fixed-broadband.
Cable (e.g. Comcast (CMCSA) and Time Warner Cable, DSL (e.g. Qwest Communications International (Q), and Wireless Internet Service Providers (WISPs) who sell access to hot spots (e.g. EarthLink (ELNK) all stand to lose business with the success of WiMax, a clear technology substitue. However, this is similarly true with the success of W-CDMA, as long as wireless 3G carriers offer price competition to the "always-on broadband" currently offered by Cable and DSL providers. This is unlikely in the short run, however, because wireless carriers have made a mint in per-minute billing and won't move to flat-rate unless they have to. Thus, they'd prefer to see W-CDMA and voice-based technology win the race.
Alcatel (ALU), Nokia (NOK), and Motorola (MOT) three large wireless equipment vendors that have all moved through the wireless evolution with carriers. They're better poised for W-CDMA to win, but have all agreed to offer WiMax functionality in future products. They are clearly hedging their bets here.
AOL and other Internet service providers offering dial-up Internet connectivity have already seen their businesses decline, and the competition between W-CDMA and WiMax will further put downward pressure on broadband Internet access subscription fees, which will further drive people away from dial-up. WiMax, however, is more of a threat because those who use dial-up are more likely not to need mobile broadband access, and WiMax is gaining the most traction these days in fixed-broadband.
Who benefits if W-CDMA Wins
AT&T Mobility and Verizon Wireless , the two largest U.S. carriers, would like to see W-CDMA win. AT&T Mobility is uniquely positioned in the U.S. as the largest UMTS (based on W-CDMA) network, and Verizon Wireless is on a CDMA2000 network, whose broadband evolution is more likely to tap into WCDMA than WiMax. and as well as all other 3G wireless broadband providers, are deeply concerned about who wins the WiMax/W-CDMA battle. wants to see W-CDMA prevail and eventually move into the HSPA/LTE generation. Sprint Nextel (S), while running a CDMA2000/EV-DO network, has committed to offering a 4G WiMax Network in a partnership with Intel (INTC) Motorola (MOT), and Samsung. [3].
Cable (e.g. Comcast (CMCSA) and Time Warner Cable, DSL (e.g. Qwest Communications International (Q), and Wireless Internet Service Providers (WISPs) who sell access to hot spots (e.g. EarthLink (ELNK) all stand to lose business with the success of WiMax, a clear technology substitue. However, this is similarly true with the success of W-CDMA, as long as wireless 3G carriers offer price competition to the "always-on broadband" currently offered by Cable and DSL providers. This is unlikely in the short run, however, because wireless carriers have made a mint in per-minute billing and won't move to flat-rate unless they have to. Thus, they'd prefer to see W-CDMA and voice-based technology win the race.
Alcatel (ALU), Nokia (NOK), and Motorola (MOT) three large wireless equipment vendors that have all moved through the wireless evolution with carriers. They're better poised for W-CDMA to win, but have all agreed to offer WiMax functionality in future products. They are clearly hedging their bets here.
AOL and other Internet service providers offering dial-up Internet connectivity have already seen their businesses decline, and the competition between W-CDMA and WiMax will further put downward pressure on broadband Internet access subscription fees, which will further drive people away from dial-up. WiMax, however, is more of a threat because those who use dial-up are more likely not to need mobile broadband access, and WiMax is gaining the most traction these days in fixed-broadband.
Cable (e.g. Comcast (CMCSA) and Time Warner Cable, DSL (e.g. Qwest Communications International (Q), and Wireless Internet Service Providers (WISPs) who sell access to hot spots (e.g. EarthLink (ELNK) all stand to lose business with the success of WiMax, a clear technology substitue. However, this is similarly true with the success of W-CDMA, as long as wireless 3G carriers offer price competition to the "always-on broadband" currently offered by Cable and DSL providers. This is unlikely in the short run, however, because wireless carriers have made a mint in per-minute billing and won't move to flat-rate unless they have to. Thus, they'd prefer to see W-CDMA and voice-based technology win the race.
Alcatel (ALU), Nokia (NOK), and Motorola (MOT) three large wireless equipment vendors that have all moved through the wireless evolution with carriers. They're better poised for W-CDMA to win, but have all agreed to offer WiMax functionality in future products. They are clearly hedging their bets here.
AOL and other Internet service providers offering dial-up Internet connectivity have already seen their businesses decline, and the competition between W-CDMA and WiMax will further put downward pressure on broadband Internet access subscription fees, which will further drive people away from dial-up. WiMax, however, is more of a threat because those who use dial-up are more likely not to need mobile broadband access, and WiMax is gaining the most traction these days in fixed-broadband.
Mobile Wireless Design Considerations
Mobile Wireless TDMA Design Considerations
# Number of logical channels (number of time slots in TDMA frame): 8
# Maximum cell radius (R): 35 km
# Frequency: region around 900 MHz
# Maximum vehicle speed (Vm):250 km/hr
# Maximum coding delay: approx. 20 ms
# Maximum delay spread (m): 10 s
# Bandwidth: Not to exceed 200 kHz (25 kHz per channel)
Mobile Wireless CDMA Design Considerations
# Soft Handoff – mobile station temporarily connected to more than one base station simultaneously
# RAKE receiver – when multiple versions of a signal arrive more than one chip interval apart, RAKE receiver attempts to recover signals from multiple paths and combine them
-This method achieves better performance than simply recovering dominant signal and treating remaining signals as noise
# Number of logical channels (number of time slots in TDMA frame): 8
# Maximum cell radius (R): 35 km
# Frequency: region around 900 MHz
# Maximum vehicle speed (Vm):250 km/hr
# Maximum coding delay: approx. 20 ms
# Maximum delay spread (m): 10 s
# Bandwidth: Not to exceed 200 kHz (25 kHz per channel)
Mobile Wireless CDMA Design Considerations
# Soft Handoff – mobile station temporarily connected to more than one base station simultaneously
# RAKE receiver – when multiple versions of a signal arrive more than one chip interval apart, RAKE receiver attempts to recover signals from multiple paths and combine them
-This method achieves better performance than simply recovering dominant signal and treating remaining signals as noise
EDGE
EDGE
* Enhanced data rates for GSM evolution.
* GSM/GPRS-Network Enhancementr
* Datarate compareable to UMTS Network (384 kBit/s and more).
* Changing GSM Modulation from GMSK to 8PSK.
* 16-QAM was also proposed for EDGE.
* EDGE provide both PS & CS services.
* QoS profile is defined for each sevice with QoS parameters include priority, reliability & delay.
* Link adaptation scheme is EDGE regularly estimate the link quality and select the appropriate modulation and coding scheme to maximize the user bit rate.
* Incremental redundancy is also used.
* RLC/MAC layer of GPRS need to be modified to accomodate features for multiplexing & link adaptation.
* Enhanced data rates for GSM evolution.
* GSM/GPRS-Network Enhancementr
* Datarate compareable to UMTS Network (384 kBit/s and more).
* Changing GSM Modulation from GMSK to 8PSK.
* 16-QAM was also proposed for EDGE.
* EDGE provide both PS & CS services.
* QoS profile is defined for each sevice with QoS parameters include priority, reliability & delay.
* Link adaptation scheme is EDGE regularly estimate the link quality and select the appropriate modulation and coding scheme to maximize the user bit rate.
* Incremental redundancy is also used.
* RLC/MAC layer of GPRS need to be modified to accomodate features for multiplexing & link adaptation.
Wireless vs Wired
Wireless vs Wired
-Wireless operates on the unreliable radio channel that needs far more complex PHY layer as well as connection management
-Wireless should arrange change of connection point during the moves by a more complex registration and call routing
-Wireless has limited number of channels (radio frequency bands) that should be managed to be shared among a huge number of users
-Wireless needs security (authenticate and ciphering) to avoid fraud and preserve privacy
-Wireless, due to bandwidth scarcity, needs more complex source coding techniques (e.g. for voice or video)
-Wireless needs permanent and temporary addressing to support mobility
-Wireless mobile operates out of the battery energy and needs power management
-Wireless terminals use small screens that needs special graphics
Technical Aspects of Wireless Infrastructure
-Network deployment planning
-Mobility and location management
-Radio resource and power management
-Security
-Wireless operates on the unreliable radio channel that needs far more complex PHY layer as well as connection management
-Wireless should arrange change of connection point during the moves by a more complex registration and call routing
-Wireless has limited number of channels (radio frequency bands) that should be managed to be shared among a huge number of users
-Wireless needs security (authenticate and ciphering) to avoid fraud and preserve privacy
-Wireless, due to bandwidth scarcity, needs more complex source coding techniques (e.g. for voice or video)
-Wireless needs permanent and temporary addressing to support mobility
-Wireless mobile operates out of the battery energy and needs power management
-Wireless terminals use small screens that needs special graphics
Technical Aspects of Wireless Infrastructure
-Network deployment planning
-Mobility and location management
-Radio resource and power management
-Security
WCDMA Basic Modes
WCDMA has two basic modes of operation
(1)TDD (Time Division Duplex).
(2)FDD (Frequency Division Duplex).
Duplex communications:
Downlink Channel
From Node B (Base Station) to UE (User Equipment).
Uplink Channel
From UE to Node B
Model simulates transmission of information data (DCH – Dedicated Channel) during a connection.
(1)TDD (Time Division Duplex).
(2)FDD (Frequency Division Duplex).
Duplex communications:
Downlink Channel
From Node B (Base Station) to UE (User Equipment).
Uplink Channel
From UE to Node B
Model simulates transmission of information data (DCH – Dedicated Channel) during a connection.
WCDMA
• WCDMA stands for Wideband Code Division Multiple Access.
• WCDMA is one of the five air-interfaces adopted by the ITU under the name "IMT-2000 Direct Spread”.
• WCDMA can support multiple and simultaneous communications such as voice, images, data, and video.
–Very high and variable bit rates:
•144 kbps: vehicle speed, rural environ.
•384 kbps: walking speed, urban outdoor.
•2048 kbps: fixed, indoor.
–Different QoS for different connections.
–High spectrum efficient.
–Coexistence with current systems.
• WCDMA is being specified by the 3GPP (Third Generation Partnership Project).
• WCDMA is one of the five air-interfaces adopted by the ITU under the name "IMT-2000 Direct Spread”.
• WCDMA can support multiple and simultaneous communications such as voice, images, data, and video.
–Very high and variable bit rates:
•144 kbps: vehicle speed, rural environ.
•384 kbps: walking speed, urban outdoor.
•2048 kbps: fixed, indoor.
–Different QoS for different connections.
–High spectrum efficient.
–Coexistence with current systems.
• WCDMA is being specified by the 3GPP (Third Generation Partnership Project).
Tuesday, April 7, 2009
UMTS – Applications
Conversational Class applications
· Circuit switched voice service.
Similar to GSM using 24.008 protocol and AMR speech coding.
· Packet Switched Voiced Service
Like Voice over IP service. AMR encoding used for speech coding.
Streaming Class applications
- Streaming / Download (Video, Audio)
- Videoconferences
Video and audio streaming as mentioned above using buffering mechanisms at the receiver to compensate for delay in the bearer service.
Interactive Class applications
· Fast Internet / Intranet.
· Mobile E-Commerce (M-Commerce)
· Remote Login
Here the overall service is determined by the request response delay.
Background Class applications
Any non –real time applications like
- Multimedia-Messaging, E-Mail
- FTP Access
- Mobile Entertainment (Games)
Here Error-free is the criteria with delay insentivity.
UMTS in the international context
The Commission considers that the further development of UMTS should aim at establishing a global standard, much like what was done for GSM. The Commission calls on Member States and industry at large to join its efforts and take the following actions
· Proposing and promoting the UMTS standard (under development within ETSI) as a key element of the IMT-2000 recommendation currently in preparation at the ITU.
· Securing spectrum availability for UMTS for its longer term needs by seeking adequate frequency allocations through the WRC process. In particular, the Commission supports the CEPT and the UMTS Forum position to propose the inclusion of the issue in the agenda of the WRC-99 conference, at the forthcoming WRC-97. The Commission also fully supports the concerted efforts of the UMTS Forum towards the world community to secure further spectrum for terrestrial mobile communications.
· Encouraging contact between interested industry organisations, standardisation bodies and administrations of Europe and those of our commercial partners in order to promote the goal of a globally interoperable UMTS system and to help in establishing co-operation and alliances among private partners at an early stage of UMTS development.
· Initiate at an early stage the discussion of market access and free circulation of UMTS systems and terminals building on the experiences of the GM PCS MoU.
· Proposing and promoting the UMTS standard (under development within ETSI) as a key element of the IMT-2000 recommendation currently in preparation at the ITU.
· Securing spectrum availability for UMTS for its longer term needs by seeking adequate frequency allocations through the WRC process. In particular, the Commission supports the CEPT and the UMTS Forum position to propose the inclusion of the issue in the agenda of the WRC-99 conference, at the forthcoming WRC-97. The Commission also fully supports the concerted efforts of the UMTS Forum towards the world community to secure further spectrum for terrestrial mobile communications.
· Encouraging contact between interested industry organisations, standardisation bodies and administrations of Europe and those of our commercial partners in order to promote the goal of a globally interoperable UMTS system and to help in establishing co-operation and alliances among private partners at an early stage of UMTS development.
· Initiate at an early stage the discussion of market access and free circulation of UMTS systems and terminals building on the experiences of the GM PCS MoU.
Frequency issues related to UMTS
The issue of spectrum pricing
Several industry contributors argued that high pricing of spectrum would distort the market and damage the uptake of UMTS services. Little support was expressed for the use of market mechanisms, in particular, auctions, since these tend to overprice spectrum, create uncertainty and undermine the development of a healthy industry. Some also felt that auctions risked favouring the entry of non-European players into the European market place. On the other hand, some Member States consider that spectrum pricing should reflect its economic value.
Estimates of how much spectrum is required
Industry players argued that the 2 x 40 MHz currently designated by the ERC[1] will prove to be insufficient for the needs of a competitive market place to start up. The UMTS Forum identified a minimum requirement of 2 x 40 MHz to be released now, together with another band of 20 MHz which will be needed for non-public, in-building, low mobility systems. In the longer term, the Forum considered current market forecasts justify a claim for the full 155 MHz identified for terrestrial mobile communications by WARC-92 to be available by the year 2005, with a further 185 MHz required for terrestrial services by the year 2010. It was suggested that steps should therefore be taken by the CEPT to place the subject of additional spectrum for IMT-2000 on the WRC-99 agenda.
Additionally, the ITU has identified 60 MHz for the satellite component of IMT-2000, with forecasts of a need for a further 30 MHz by the year 2010.
The idea of sharing a common pool of spectrum was rejected by industry who argued that it would be a significant disincentive for operators, whilst others doubt whether it would be technically possible or indicated that it would create monopoly structures.
In terms of the UMTS market, several comments stressed that the development of the UMTS market makes it necessary that sufficient spectrum is available to cover the needs of all operators seeking a license. This would also have an effect on the future development/evolution of the UMTS standard.
ERC Decision on the frequency bands for the introduction of Universal Mobile Telecommunications Systems (UMTS), ERC/DEC/(97)07, 30 June 1997
When and how should decisions on spectrum be taken?
The UMTS Forum called for a co-ordinated approach by all relevant authorities in Europe to ensure a timely approach to identifying, liberating and allocating UMTS spectrum. Nevertheless, some argue that the detailed planning of the spectrum can only be done at a later stage when a clearer picture of UMTS has emerged.
Several industry contributors argued that high pricing of spectrum would distort the market and damage the uptake of UMTS services. Little support was expressed for the use of market mechanisms, in particular, auctions, since these tend to overprice spectrum, create uncertainty and undermine the development of a healthy industry. Some also felt that auctions risked favouring the entry of non-European players into the European market place. On the other hand, some Member States consider that spectrum pricing should reflect its economic value.
Estimates of how much spectrum is required
Industry players argued that the 2 x 40 MHz currently designated by the ERC[1] will prove to be insufficient for the needs of a competitive market place to start up. The UMTS Forum identified a minimum requirement of 2 x 40 MHz to be released now, together with another band of 20 MHz which will be needed for non-public, in-building, low mobility systems. In the longer term, the Forum considered current market forecasts justify a claim for the full 155 MHz identified for terrestrial mobile communications by WARC-92 to be available by the year 2005, with a further 185 MHz required for terrestrial services by the year 2010. It was suggested that steps should therefore be taken by the CEPT to place the subject of additional spectrum for IMT-2000 on the WRC-99 agenda.
Additionally, the ITU has identified 60 MHz for the satellite component of IMT-2000, with forecasts of a need for a further 30 MHz by the year 2010.
The idea of sharing a common pool of spectrum was rejected by industry who argued that it would be a significant disincentive for operators, whilst others doubt whether it would be technically possible or indicated that it would create monopoly structures.
In terms of the UMTS market, several comments stressed that the development of the UMTS market makes it necessary that sufficient spectrum is available to cover the needs of all operators seeking a license. This would also have an effect on the future development/evolution of the UMTS standard.
ERC Decision on the frequency bands for the introduction of Universal Mobile Telecommunications Systems (UMTS), ERC/DEC/(97)07, 30 June 1997
When and how should decisions on spectrum be taken?
The UMTS Forum called for a co-ordinated approach by all relevant authorities in Europe to ensure a timely approach to identifying, liberating and allocating UMTS spectrum. Nevertheless, some argue that the detailed planning of the spectrum can only be done at a later stage when a clearer picture of UMTS has emerged.
3G TECHNOLOGY IN LATIN AMERICA
Most of Latin-American countries face uncertainty to carry out investments on third generation UMTS networks because of their available frequency bands inconsistency with the ones used in Japan and Europe, the recent initiatives in United States to deploy UMTS on the same 2G bands, the permanent discussion to incur on other frequency bands, the great investments needed and the potential existing market to data services development
Investment income-yield capacity on 2G networks
Activities on Telecommunication areas are commercial activities which generate great capital investments and need to be recovered in long-term. Recently, great investments on the Latin American region have been generated to create the existing scenario with GSM technology. The introduction of this technology has solved many existing problems on former systems. The great mobile market competence and the great prepaid segment development have lead operators to introduce permanent technological innovations and great marketing expenditures which require reasonable periods to recover investments made.
Voice market still offer huge growth gaps on 2G, which allow making investment profitable. 3G deployment requires huge investments to install from cero parallel networks along with the existing ones. In addition has to be considered the fact of the licenses given back in several European countries and the recurrent discussion about the impact of the election of frequency bands on the quantity of base stations to be installed.
In this sense, Latin America has been cautiously moving forward on data services introduction on the existing 2G networks using GPRS and EDGE.
The data market
From the information obtained from Europe to five years since 3G license bidding process was carried out, it’s observed that data services usage offered by this technology have been lower than expected and a longer period of time is required to create a significant demand.
From above we conclude that it is necessary to seriously consider the potential service demand and data applications existing on the market, being the main benefit of 3G technology. Meanwhile, in Latin America there are still voice market growth gaps, so it is reasonable to exploit this market and gradually introduce data services using available updates within the same GSM networks in 2G.
Technological maturity
In relation to technologies, it is observed that in UMTS there are already several revisions which improve performance of former versions adopted in Japan and it’s been also going ahead in the evolution from UMTS to others improved radio interfaces. There are also advances in internet broadband access technologies, which in the short term will start to introduce mobility and voice capacity over IP.
Given the great variety of solutions and technological versions, it seems cautious to await for a greater maturity in markets in order to take advantage of UMTS universalization benefits and the eventual complementing with emerging technologies. Besides being expensive technologies, very complex and of recently introduction, which generates the uncertainties mentioned before, today these are no longer competitive comparing with widely tested technologies on local fixed telephony.
Investment income-yield capacity on 2G networks
Activities on Telecommunication areas are commercial activities which generate great capital investments and need to be recovered in long-term. Recently, great investments on the Latin American region have been generated to create the existing scenario with GSM technology. The introduction of this technology has solved many existing problems on former systems. The great mobile market competence and the great prepaid segment development have lead operators to introduce permanent technological innovations and great marketing expenditures which require reasonable periods to recover investments made.
Voice market still offer huge growth gaps on 2G, which allow making investment profitable. 3G deployment requires huge investments to install from cero parallel networks along with the existing ones. In addition has to be considered the fact of the licenses given back in several European countries and the recurrent discussion about the impact of the election of frequency bands on the quantity of base stations to be installed.
In this sense, Latin America has been cautiously moving forward on data services introduction on the existing 2G networks using GPRS and EDGE.
The data market
From the information obtained from Europe to five years since 3G license bidding process was carried out, it’s observed that data services usage offered by this technology have been lower than expected and a longer period of time is required to create a significant demand.
From above we conclude that it is necessary to seriously consider the potential service demand and data applications existing on the market, being the main benefit of 3G technology. Meanwhile, in Latin America there are still voice market growth gaps, so it is reasonable to exploit this market and gradually introduce data services using available updates within the same GSM networks in 2G.
Technological maturity
In relation to technologies, it is observed that in UMTS there are already several revisions which improve performance of former versions adopted in Japan and it’s been also going ahead in the evolution from UMTS to others improved radio interfaces. There are also advances in internet broadband access technologies, which in the short term will start to introduce mobility and voice capacity over IP.
Given the great variety of solutions and technological versions, it seems cautious to await for a greater maturity in markets in order to take advantage of UMTS universalization benefits and the eventual complementing with emerging technologies. Besides being expensive technologies, very complex and of recently introduction, which generates the uncertainties mentioned before, today these are no longer competitive comparing with widely tested technologies on local fixed telephony.
3G Systems
3G Systems are intended to provide a global mobility with wide range of services including telephony, paging, messaging, Internet and broadband data. International Telecommunication Union (ITU) started the process of defining the standard for third generation systems, referred to as International Mobile Telecommunications 2000 (IMT-2000). In Europe European Telecommunications Standards Institute (ETSI) was responsible of UMTS standardisation process. In 1998 Third Generation Partnership Project (3GPP) was formed to continue the technical specification work. 3GPP has five main UMTS standardisation areas: Radio Access Network, Core Network, Terminals, Services and System Aspects and GERAN.
3GPP Radio Access group is responsible of:
Radio Layer 1, 2 and 3 RR specification
Iub, Iur and Iu Interfaces
UTRAN Operation and Maintenance requirements
BTS radio performance specification
Conformance test specification for testing of radio aspects of base stations
Specifications for radio performance aspects from the system point of view
3GPP Core Network group is responsible of:
Mobility management, call connection control signalling between the user equipment and the core network.
Core network signalling between the core network nodes.
Definition of interworking functions between the core network and external networks.
Packet related issues.
Core network aspects of the lu interface and Operation and Maintenance requirements3GPP Terminal group is responsible of:
Service capability protocols
Messaging
Services end-to-end interworking
USIM to Mobile Terminal interface
Model/framework for terminal interfaces and services (application) execution
Conformance test specifications of terminals, including radio aspects
3GPP Terminal group is responsible of:
Service capability protocols
Messaging
Services end-to-end interworking
USIM to Mobile Terminal interface
Model/framework for terminal interfaces and services (application) execution
Conformance test specifications of terminals, including radio aspects
3GPP Services and System Aspects group is responsible of:
Definition of services and feature requirements.
Development of service capabilities and service architecture for cellular, fixed and cordless applications.
Charging and Accounting
Network Management and Security Aspects
Definition, evolution, and maintenance of overall architecture
Monday, April 6, 2009
UMTS-TDD
UMTS-TDD is a mobile data network standard built upon the UMTS 3G cellular mobile phone standard, using a TD-CDMA, TD-SCDMA, or other 3GPP-approved, air interface that uses Time Division Duplexing to duplex spectrum between the up-link and down-link. While a full implementation of UMTS, it is mainly used to provide Internet access in circumstances similar to those where WiMAX might be used. UMTS-TDD is not directly compatible with UMTS: a device designed to use one standard cannot, unless specifically designed to, work on the other, because of the difference in air interface technologies and frequencies used.
TD-CDMA
TD-CDMA is the primary air interface used by UMTS-TDD. It uses increments of 5MHz of spectrum, with each slice divided into 10ms frames containing fifteen time slots (1500 per second). The time slots are allocated in fixed percentage for downlink and uplink. Code Division Multiple Access is used within each time slot to multiplex streams from or to multiple transceivers.[1]
TD-CDMA is an IMT-2000 3G air interface, classified as IMT-TD Time-Division, and is standardized in UMTS by the 3GPP as UTRA TDD-HCR. TD-CDMA is closely related to W-CDMA, and provides the same types of channels where possible. W-CDMA's HSDPA/HSUPA enhancements are also implemented under TD-CDMA.[2]
An alternative air interface for UMTS-TDD is TD-SCDMA, which uses 1.6MHz slices of spectrum, and is standardized in UMTS by the 3GPP as UTRA TDD-LCR.
Unlicensed UMTS-TDD
In Europe, CEPT allocated the 2010-2020MHz range for a variant of UMTS-TDD designed for unlicensed, self-provided use.[3] Some telecom groups and jurisdictions have proposed withdrawing this service in favour of licensed UMTS-TDD,[4] due to lack of demand, and lack of development of a UMTS TDD air interface technology suitable for deployment in this band
Comparison with UMTS
Ordinary UMTS uses a W-CDMA air interface technology and Frequency Division Duplexing, meaning that the up-link and down-link transmit on different frequencies. UMTS is usually transmitted on frequencies assigned for 1G, 2G, or 3G mobile telephone service in the countries of operation.
UMTS-TDD uses time division duplexing, allowing the up-link and down-link to share the same spectrum. This allows the operator to more flexibly divide the usage of available spectrum according to traffic patterns. For ordinary phone service, you would expect the up-link and down-link to carry approximately equal amounts of data (because every phone call needs a voice transmission in either direction), but Internet-oriented traffic is more frequently one-way. For example, when browsing a website, the user will send commands, which are short, to the server, but the server will send whole files, that are generally larger than those commands, in response.
UMTS-TDD tends to be allocated frequency intended for mobile/wireless Internet services rather than used on existing cellular frequencies. This is, in part, because TDD duplexing is not normally allowed on cellular, PCS/PCN, and 3G frequencies. TDD technologies open up the usage of left-over unpaired spectrum.
Europe-wide, several bands are provided either specifically for UMTS-TDD or for similar technologies. These are 1900MHz and 1920MHz and between 2010MHz and 2025MHz. In several countries the 2500-2690 MHz band (also known as MMDS in the USA) have been used for UMTS-TDD deployments. Additionally, spectrum around the 3.5GHz range has been allocated in some countries, notably Britain, in a technology-neutral environment.
Deployment
UMTS-TDD has been deployed for public and/or private networks in at least nineteen countries around the world, with live systems in, amongst other countries, Australia, Czech Republic, France, Germany, Japan, New Zealand, South Africa, the UK, and the USA.[5]
Deployments in the US thus far have been limited. It has been selected for a public safety support network used by emergency responders in New York,[6] but outside of some experimental systems, notably one from Nextel, thus far the WiMAX standard appears to have gained greater traction as a general mobile Internet access system.
Competing Standards
A variety of Internet-access systems exist which provide broadband speed access to the net. These include WiMAX and HIPERMAN. UMTS-TDD has the advantages of being able to use an operator's existing UMTS/GSM infrastructure, should it have one, and that it includes UMTS modes optimized for circuit switching should, for example, the operator want to offer telephone service. UMTS-TDD's performance is also more consistent. However, UMTS-TDD deployers often have regulatory problems with taking advantage of some of the services UMTS compatibility provides. For example, UMTS-TDD spectrum in the UK cannot be used to provide telephone service, though the regulator OFCOM is discussing the possibility of allowing it at some point in the future. Few operators considering UMTS-TDD have existing UMTS/GSM infrastructure.
Additionally, the WiMAX and HIPERMAN systems provide significantly larger bandwidths when the mobile station is in close proximity to the tower.
Like most mobile Internet access systems, many users who might otherwise choose UMTS-TDD will find their needs covered by the ad hoc collection of unconnected Wifi access points at many restaurants and transportation hubs, and/or by Internet access already provided by their mobile phone operator. By comparison, UMTS-TDD (and systems like WiMAX) offers mobile, and more consistent, access than the former, and generally faster access than the latter.
References
TD-CDMA
TD-CDMA is the primary air interface used by UMTS-TDD. It uses increments of 5MHz of spectrum, with each slice divided into 10ms frames containing fifteen time slots (1500 per second). The time slots are allocated in fixed percentage for downlink and uplink. Code Division Multiple Access is used within each time slot to multiplex streams from or to multiple transceivers.[1]
TD-CDMA is an IMT-2000 3G air interface, classified as IMT-TD Time-Division, and is standardized in UMTS by the 3GPP as UTRA TDD-HCR. TD-CDMA is closely related to W-CDMA, and provides the same types of channels where possible. W-CDMA's HSDPA/HSUPA enhancements are also implemented under TD-CDMA.[2]
An alternative air interface for UMTS-TDD is TD-SCDMA, which uses 1.6MHz slices of spectrum, and is standardized in UMTS by the 3GPP as UTRA TDD-LCR.
Unlicensed UMTS-TDD
In Europe, CEPT allocated the 2010-2020MHz range for a variant of UMTS-TDD designed for unlicensed, self-provided use.[3] Some telecom groups and jurisdictions have proposed withdrawing this service in favour of licensed UMTS-TDD,[4] due to lack of demand, and lack of development of a UMTS TDD air interface technology suitable for deployment in this band
Comparison with UMTS
Ordinary UMTS uses a W-CDMA air interface technology and Frequency Division Duplexing, meaning that the up-link and down-link transmit on different frequencies. UMTS is usually transmitted on frequencies assigned for 1G, 2G, or 3G mobile telephone service in the countries of operation.
UMTS-TDD uses time division duplexing, allowing the up-link and down-link to share the same spectrum. This allows the operator to more flexibly divide the usage of available spectrum according to traffic patterns. For ordinary phone service, you would expect the up-link and down-link to carry approximately equal amounts of data (because every phone call needs a voice transmission in either direction), but Internet-oriented traffic is more frequently one-way. For example, when browsing a website, the user will send commands, which are short, to the server, but the server will send whole files, that are generally larger than those commands, in response.
UMTS-TDD tends to be allocated frequency intended for mobile/wireless Internet services rather than used on existing cellular frequencies. This is, in part, because TDD duplexing is not normally allowed on cellular, PCS/PCN, and 3G frequencies. TDD technologies open up the usage of left-over unpaired spectrum.
Europe-wide, several bands are provided either specifically for UMTS-TDD or for similar technologies. These are 1900MHz and 1920MHz and between 2010MHz and 2025MHz. In several countries the 2500-2690 MHz band (also known as MMDS in the USA) have been used for UMTS-TDD deployments. Additionally, spectrum around the 3.5GHz range has been allocated in some countries, notably Britain, in a technology-neutral environment.
Deployment
UMTS-TDD has been deployed for public and/or private networks in at least nineteen countries around the world, with live systems in, amongst other countries, Australia, Czech Republic, France, Germany, Japan, New Zealand, South Africa, the UK, and the USA.[5]
Deployments in the US thus far have been limited. It has been selected for a public safety support network used by emergency responders in New York,[6] but outside of some experimental systems, notably one from Nextel, thus far the WiMAX standard appears to have gained greater traction as a general mobile Internet access system.
Competing Standards
A variety of Internet-access systems exist which provide broadband speed access to the net. These include WiMAX and HIPERMAN. UMTS-TDD has the advantages of being able to use an operator's existing UMTS/GSM infrastructure, should it have one, and that it includes UMTS modes optimized for circuit switching should, for example, the operator want to offer telephone service. UMTS-TDD's performance is also more consistent. However, UMTS-TDD deployers often have regulatory problems with taking advantage of some of the services UMTS compatibility provides. For example, UMTS-TDD spectrum in the UK cannot be used to provide telephone service, though the regulator OFCOM is discussing the possibility of allowing it at some point in the future. Few operators considering UMTS-TDD have existing UMTS/GSM infrastructure.
Additionally, the WiMAX and HIPERMAN systems provide significantly larger bandwidths when the mobile station is in close proximity to the tower.
Like most mobile Internet access systems, many users who might otherwise choose UMTS-TDD will find their needs covered by the ad hoc collection of unconnected Wifi access points at many restaurants and transportation hubs, and/or by Internet access already provided by their mobile phone operator. By comparison, UMTS-TDD (and systems like WiMAX) offers mobile, and more consistent, access than the former, and generally faster access than the latter.
References
^ "UMTS World TD-CDMA information". umtsworld.com. http://www.umtsworld.com/technology/tdcdma.htm. Retrieved on 2008-02-28.
^ "IPWireless Ships First Commercial 3GPP Chipset with Full HSDPA Implementation". ipwireless.com. http://www.ipwireless.com/news/press_020805.html. Retrieved on 2008-02-28.
^ "ERC/DEC/(99)25 EU Recommendation on UMTS TDD". ero.dk. http://www.ero.dk/documentation/docs/doc98/official/pdf/DEC9925E.PDF. Retrieved on 2008-02-28.
^ "Award_of_available_spectrum:_2500-2690_MHz,_2010-2025_MHz_and_2290-2300_MHz". ofcom.org.uk. http://www.ofcom.org.uk/consult/condocs/2ghzawards/2ghzawards.pdf. Retrieved on 2008-02-28.
^ "UMTS-TDD Alliance list of Deployments". umtstdd.org. http://www.umtstdd.org/deployments.html. Retrieved on 2008-02-28.
^ "Northrop Grumman Wins $500 Million New York City Broadband Mobile Wireless Contract". ipwireless.com. http://www.ipwireless.com/news/press_091206.html. Retrieved on 2008-02-28.
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