Tuesday, April 21, 2009
Thursday, April 16, 2009
Monday, April 13, 2009
Thursday, April 9, 2009
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.
Introduction of 3g for mobile communication system
The third generation (3G) of mobile communication system is currently under implementation and rollout in Norway. The development and diffusion of 3Gh in Europe is in general facing major delays and difficulties, drawing a picture in sharp contrast with the great expectations formerly associated with the technology. The difficulties and delays occur for many reasons, and some important ones will be spelled out here by describing the basic features of 3G, the innovation and rollout process and the different stakeholders. Using the concepts of innovations and the conceptual framework of innovation regimes described by Godø (Godø 1995), the current state of 3G in Norway is described, followed by explanation concerning the state of the game as well as some brief suggestions for the further development.
The implementation of 3G networks in Norway and the other European countries follows the European Telecommunications Standards Institute (ETSI) standard Universal Mobile Telephone system (UMTS). The aim of the UMTS standard is to create one European mobile telephone network enabling users to use their mobile handsets to access high-value services seamlessly in Europe, and finally all over the world. Telecommunication systems have a historically high strategic significance in modern and industrial societies (Godø 1995). This also concerns UMTS in future Europe as part of the information society spelled out by The Commission of European Communities:
“Advanced wireless platforms such as 3G are an essential building block to achieve the goals of the Information Society in terms of consumer demand, productivity, competitiveness and job creation.”(EU 2002).
In the scattered populated and topologically complex geography (in terms of mobile infrastructure implementation) of Norway, the governmental telecommunication policy has also historically been seen as fundamental to sustainable regional development, are described as the political aims for UMTS in the hearing of the Norwegian Ministry of Transport and Communications concerning the Norwegian mobile communication market:
“Ensure households and businesses all over the country basic telecommunication services with high quality and low price; Ensure maximum of value creation and efficient utilisation of the resources in the telecom sector by ensuring access and efficient use of the public telecommunication network and services by effective competition.” [Authors translation](NMTC 2002a).
Telecommunication is in addition seen as a source for industrial and job opportunities, by exporting technology and knowledge to other European and non-European countries (NMTC 1999). The achievement of these stated aims is expected to come by enabling effective competition in a liberalised telecommunication market. In the case of Norway it can be argued that policy makers and the telecommunication operators both have to meet the classical challenges for less developed regions of the world described by McDowell: The expansion of the telecommunication infrastructure due to the geographical challenges, and the challenges for the post-industrial North: the issues of competition, pricing, and social objectives (McDowell 2001), to succeed in implementing UMTS.
The strategic importance of telecommunication is also reflected in the numerous national and international governmental bodies concerned with the use of frequencies, attribution of licences and competition. In Norway, the Norwegian Ministry of Transportation and Communication, the Norwegian Post and Telecommunications Authority, the International Telecommunication Union (ITU) and different EU[1] bodies have the major stake in the current regulation policies. The operators and other stakeholders are also given a voice in numerous hearings. National regulations in telecommunication have in Norway lately undergone changes as to suite the relatively newly deregulated and liberalised European telecommunication market. The deregulation has resulted in an open market, where the monopoly situation of the state owned “Televerket” no longer exists de jure. De facto, Telenor (formerly “Televerket”) still has a significant market position in mobile communication, and together with the second largest operator: NetCom, respectively having 62.5% and 26.3% percent of subscriptions and 70.2% and 21.4% of the traffic minutes (Statistics for 2001, NPTA 2002a), the market are basically a duopoly. The strong position of Telenor have been an important issue for national regulation bodies, trying to secure the access to the existing European mobile communication system GSM network and the market for new entrants (as for example Sense, the third largest operator having 5.44% of subscriptions and 4.69% of traffic minutes) to create effective competition and correct pricing of the services. Actors (Telenor and NetCom only) with their own physical network have obviously more flexibility than the operators and service providers without. This is acknowledged by the Ministry of Transportation and Communication through obligating licensees to build parallel and completely independent UMTS networks.
1. Sharing the airRadio frequencies combined with antennas and transmission effect enables communication over different ranges. The different ranges make some frequencies more popular than other, and they eventually become crowded. Radio frequency regulation authorities are responsible for regulating the use of different frequencies so that communication doesn’t break down, as well enabling a maximum of utilization. Regulations are implemented by licensing the use and appropriate the different parts of the frequency spectrum to different purposes, and different licensees. GSM and UMTS
Norway is not a member state of the European Union, but is associated by the European Economic Area (EEA). Norway is therefore required to adapt its telecommunication regulatory framework according to EU directives through that treaty.
are appropriated different bands in the frequency spectrum, fitting the frequency regulation tables of Norway as well as Europe in general. In practice, the licensees them selves are responsible to effectuate sharing policies and avoid disturbance of other licensees and end-users. To ensure this, the very much of the spectrum requires the individual end-users to be certified prior to use. This is not the case of GSM and UMTS, as the responsibility and certification is handed over to the handset manufacturers by certification of products.
Mobile communication system configurations are based on cells. The cell is a circular area surrounding the base-stations that is delimited by the radius of reach of base-stations signals. The end-user communicates with other end-users through the base-stations that are connected with fixed cables. To keep users connected as they move between cells, or roam[1], the infrastructure must basically be configured such that cells are overlapping, illustrated by Figure
Roaming can be defined more specifically to be movement between cells or access to network of other operators nationally or globally. Here, roaming is not restricted to include only one, but both these processes.
Sharing the air is a challenge when more than one user is communicating in the same cell at the same time. If this happens, and users use the same frequencies, transmissions will brake down. These collisions can be avoided by not reusing frequencies in a cell and in adjacent cells, as frequencies used in cell c1 can be reused in cell c8, but not in the other cells (Figure 1). Mobile communication systems implements in addition more advanced procedures to share the air. GSM uses frequency sharing based on time-slots, implying that users only use a frequency for 0.5 milliseconds before others can use the frequency. Using this schema, the users must be granted new frequency and new time slot each time they switch to a new base-station when roaming, making the handover procedure complicated. The smaller cell, the more often handover must be effectuated. The high density of use in urban areas, and also in more rural due to the high penetration of mobile phones in Norway, requires in addition more sophisticated use of frequency sharing, implemented by UMTS. Instead of sharing the air by division of frequencies and time UMTS spreads radio signals over a range of frequencies, using CDMA (Code Division Multiple Access). With this schema other concurrent transmission is just seen as noise.
These schemas are called respectively frequency division multiple access (FDMA) and time division multiple access (TDMA).
This makes the theoretical simultaneous users much higher than with GSM, as well as making the handover procedures easier as the same schema and frequencies are used by any base-stations. At the same time, the bandwidth is highly dependent on the number of users in one and the same cell, as well as which kind of data is communicated. If all users in a UMTS cell are using the lowest transmission capacity (voice), 256 concurrent users can communicate simultaneously. If everyone uses maximum capacity (multimedia), only two concurrent users are possible.
The frequencies used by GSM have a range of maximum 35 kilometers while the UMTS frequencies only reach 6 kilometers, both due to the nature of the frequency band and the bandwidth provided. The range of transmission decides how large cell the base-station creates, and the needed density of base-stations. Using different effect in transmission, different cell sizes are implemented in UMTS networks to optimize the available bandwidth on the basis of user density (e.g. macro-, micro- and pico-cells). The bandwidth available will also be affected when the handsets are one the move, and decreases as the speed increases, as high-speed radio access to highly mobile users is difficult. This illustrates the need for a much higher density of UMTS base-stations, at a cost of approximately 1 million NOK each. In addition, the broadband cabled network coupling the UMTS base-stations to the cabled network would probably become as expensive as the base-stations.
Sunday, April 5, 2009
Development of Mobile Communications
Abstract
This article describes the development of GSM and 3G cellular-based mobile communication systems from the early days, where only the privileged few could communicate on the move, to the emergence of the mass market systems of today where, it seems, everyone has a mobile phone. The technology changes that have brought this about are described and the various “buzz-words” such as GPRS, EDGE, i-Mode & UMTS are explained. The story of the development of the different generations of mobile system is told and the key features of each of these generations are described. This covers an appreciation of the technology and describes some of the services and products that can be provided to customers. Finally, the article takes a brief look beyond the present day and describes some future trends and how the world of mobile communications will change.
Cellular radio operation
The key to the success of cellular radio communications systems is its efficient use of the radio spectrum and its ability to manage the mobility of a large number of connected mobile terminals. This allows a large number of users to be accommodated in a small number of frequencies.
The basis of cellular radio is that the same radio channels (frequencies) can be used over and over again thus allowing much greater capacity than the simple mobile communications systems that preceded it. This is done by limiting the range of each channel so that it does not interfere with the same frequencies used in a nearby area. The coverage area is divided into discrete cells each capable of serving a number of users who can pass seamlessly from cell to cell as they move through the network. Coverage can therefore be provided over large areas in which customers can move freely while maintaining service.
Early cellular mobile systems
1st Generation Systems
The 1st Generation cellular radio systems used analogue radio technology (usually frequency modulation). Different countries had different frequency allocations and there was little industry collaboration on the development of the systems. As a result, many different systems, that were mostly incompatible, arose in different parts of the world.
The system used in the UK was called TACS (Total Access Communications System). It was based on, but was not compatible with, the US system known as AMPS (Advanced Mobile Phone System). Cellular mobile service in the UK using TACS technology was opened by Cellnet and Vodafone in January 1985.
One of the main problems with the analogue systems is that, generally, because of the incompatible standards, it was not possible to take phones to other countries and use them (i.e. roaming was not generally possible). Also, these systems primarily provided voice communications and could not easily accommodate the increasing requirement for data communications.
The TACS service in the UK had closed down by 2001 and was superseded by the next generation system.
2nd Generation Systems
New cellular radio systems were developed to overcome the limitations of the first generation systems. In Europe, a new system based on digital techniques was proposed and developed. This is known as GSM (Global System for Mobile communications).
The Early Development of GSM
In 1982, a new body - Groupe Spécial Mobile (the original meaning of GSM) - was set up under the European body the CEPT (European Conference of Postal and Telecommunication Administrations). Its task was to specify a new mobile radio system operating at 900MHz. The first meeting was held in Sweden in December 1982 with representatives from 11 countries present. The GSM standard was conceived.
The main work started in 1987 following extensive prototyping. It was decided to adopt a digital radio interface using TDMA (Time Division Multiple Access) operating in the 900MHz frequency band. The GSM TDMA system uses 8 timeslots in a basic 200kHz carrier. GSM was designed to offer a standard set of services & features. This allows inter-operator roaming.
In 1989 the work was transferred to the European body ETSI (European Telecommunications Standards Institute). By 1990 the Phase 1 specifications were frozen. Work then started on adapting the specifications to work in the 1800MHz frequency band.
GSM Becomes a Global Standard
In 1987 a group of future GSM operators (15 operators from 13 countries) signed a Memorandum of Understanding (MoU) intending to promote the use of the GSM standard world-wide. With the change of emphasis to a world-wide standard, GSM was renamed "Global System for Mobile communications". Other countries outside Europe began to adopt the standard in particular the UAE, Hong Kong, Australia & New Zealand.
The first commercial GSM networks started service in 1991; 13 networks went live in 7 countries
The first roaming agreements were signed in 1992 and roaming started soon after. GSM was born!
General Features of the GSM Standard
The GSM standard was designed to be very flexible to allow the easy provision of services. Because there is a common standard, all GSM networks work the same way and, generally, every network can offer service to users from any other network. As a result, there is a large amount of roaming traffic and users have become used to receiving service when they travel abroad.
Another important feature of GSM is the high level of security provided. Powerful algorithms are used to authenticate users. Also, the radio interface is encrypted to a high degree of security which makes it very difficult to eavesdrop.
GSM uses a removable SIM (Subscriber Identity Module) card that holds the identity of the user. Because the SIM card can be plugged into any compatible mobile phone, users can change mobile terminals easily and take their identity with them. Also, a user’s list of names and telephone numbers can be stored on the SIM card so personal information can be transferred easily also. The SIM card has been further developed to add more processing power and memory. This allows new types of applications and operating systems to be run on the SIM that could be used by the network operator to offer customised services.
Because key interfaces are standardised, equipment from different manufacturers work together in the same network. Because all equipment works to the same specification, it is mass produced from many competing manufacturers thus lowering the cost. This also gives GSM network providers a wide choice of equipment vendors as well as the ability to “mix and match” equipment from different vendors.
Main Services Provided by the Original GSM Standard are:
Speech - Speech is digitised and good speech quality is possible in GSM's relatively low bit rate.
Data & Fax - A range of data rates up to 9600 bit/sec was standardised initially. The capability of sending and receiving Group 3 Fax was also provided. A data rate of 14.4kbit/s was later standardised.
Supplementary Services - These include Call Forwarding; Call Barring; Call Waiting, Multi-party calls; CLI (Calling Line Identification).
Short Message Service (SMS) - Text messages of up to 160 characters in length can be sent between mobile phones. Longer messages can be sent by concatenating SMS texts.
Cell Broadcast - Broadcast messages that can be customised for specific areas and for specific topics (eg weather) can be sent to all mobiles in the service area of a cell or group of cells.
Improvements to the GSM Standard in Later Standardisation Phases Included:
Better Speech Quality - New voice coders (codecs) were developed that improved speech quality and made better use of the radio capacity. These included the EFR (Enhanced Full Rate) and AMR (Adaptive Multi-Rate) codecs.
HSCSD (High Speed Circuit Switched Data) – A number of developments improved on the basic 9600bit/sec data rate provided: The HSCSD standard was developed to provide data rates greater than 64kbit/sec although in practice the rate is limited by the radio capacity and the capabilities of the mobile terminals. HSCSD gives the user dedicated multiple time slots to provide the higher rates. However, this technique is very hungry on radio resource and because multiple time slots are allocated to each user, the capacity of each radio carrier is greatly reduced. An advantage of HSCSD is that it can be used to provide “real time” services like live video because each user has dedicated resource.
GPRS (General Packet Radio Service) – This is another development intended to provide higher data rates. Like HSCSD, GPRS uses multiple time slots to increase the data throughput. Unlike HSCSD, GPRS does not allocate these slots just to one user – many users share the slots using them to send and receive data only when they need to. As a result, GPRS uses the radio resource much more efficiently than HSCSD and the capacity of the radio carrier is much higher. The way GPRS works, however, means that it cannot (currently) support “real time” services (like live video) as the user’s application cannot be guaranteed a time slot immediately when requested. The result is that variable delay is introduced to the data transmission. This makes GPRS much more suitable for “packet based” types of services such as Web browsing or downloading of data files. Practically, at present, typical rates of around 40kbit/sec (peak) can be achieved. There is scope for these rates to increase with further development of the mobile terminals and the introduction of more advanced channel coding schemes. Another feature of GPRS is that the user can set up an “always on” connection. Because the time slots are not used unless there is data to transmit, there is no overhead and the user can be permanently connected to a service such as an email server or an intranet.
EDGE (Enhanced Data for GSM Evolution) – EDGE is a modulation technique that allows each time slot on the GSM radio access to carry more data. As a result, the data rates provided by HSCSD and GPRS can be further increased. The take up of EDGE technology has been relatively small and many operators have chosen 3rd Generation systems as the route to higher data rates.
New Network Services – Some of the new services that were specified are: Multiple Subscriber Profile; Call Transfer, Calling Name Presentation and pre-pay control. Some of the new services are provided by Intelligent Network (IN) platforms (such as CAMEL) that have been introduced in the GSM core network.
Location Technologies – Basic location of the mobile can be provided by the identification of the cell and sector in use. More accurate location methods have also been developed using a variety of technologies including GPS (Global Positioning System). In some cases, it is a regulatory requirement to identify the location of the mobile for emergency calls (eg in North America).
Development of Mobile Terminals
Mobile terminals have also undergone rapid development. The early "brick-like" mobile terminals were soon superseded by more elegant models with superior performance. Battery life improved, multiple frequency bands introduced and new capabilities such as data downloading and web browsing incorporated.
More recently, many more new features have been incorporated into mobile terminals including high resolution cameras, music players, PDA (Personal Digital Assistant) and email functions and even radio and TV reception. The mobile device has become an essential "life tool" for many people.
In summary, the mobile terminal has undergone a remarkable transformation in a very short time. This has been driven by improvements in technology and manufacturing and also customer demand
A terminal that performs well and is easy to use is key to giving the user a good experience of the mobile network.
This article describes the development of GSM and 3G cellular-based mobile communication systems from the early days, where only the privileged few could communicate on the move, to the emergence of the mass market systems of today where, it seems, everyone has a mobile phone. The technology changes that have brought this about are described and the various “buzz-words” such as GPRS, EDGE, i-Mode & UMTS are explained. The story of the development of the different generations of mobile system is told and the key features of each of these generations are described. This covers an appreciation of the technology and describes some of the services and products that can be provided to customers. Finally, the article takes a brief look beyond the present day and describes some future trends and how the world of mobile communications will change.
Cellular radio operation
The key to the success of cellular radio communications systems is its efficient use of the radio spectrum and its ability to manage the mobility of a large number of connected mobile terminals. This allows a large number of users to be accommodated in a small number of frequencies.
The basis of cellular radio is that the same radio channels (frequencies) can be used over and over again thus allowing much greater capacity than the simple mobile communications systems that preceded it. This is done by limiting the range of each channel so that it does not interfere with the same frequencies used in a nearby area. The coverage area is divided into discrete cells each capable of serving a number of users who can pass seamlessly from cell to cell as they move through the network. Coverage can therefore be provided over large areas in which customers can move freely while maintaining service.
Early cellular mobile systems
1st Generation Systems
The 1st Generation cellular radio systems used analogue radio technology (usually frequency modulation). Different countries had different frequency allocations and there was little industry collaboration on the development of the systems. As a result, many different systems, that were mostly incompatible, arose in different parts of the world.
The system used in the UK was called TACS (Total Access Communications System). It was based on, but was not compatible with, the US system known as AMPS (Advanced Mobile Phone System). Cellular mobile service in the UK using TACS technology was opened by Cellnet and Vodafone in January 1985.
One of the main problems with the analogue systems is that, generally, because of the incompatible standards, it was not possible to take phones to other countries and use them (i.e. roaming was not generally possible). Also, these systems primarily provided voice communications and could not easily accommodate the increasing requirement for data communications.
The TACS service in the UK had closed down by 2001 and was superseded by the next generation system.
2nd Generation Systems
New cellular radio systems were developed to overcome the limitations of the first generation systems. In Europe, a new system based on digital techniques was proposed and developed. This is known as GSM (Global System for Mobile communications).
The Early Development of GSM
In 1982, a new body - Groupe Spécial Mobile (the original meaning of GSM) - was set up under the European body the CEPT (European Conference of Postal and Telecommunication Administrations). Its task was to specify a new mobile radio system operating at 900MHz. The first meeting was held in Sweden in December 1982 with representatives from 11 countries present. The GSM standard was conceived.
The main work started in 1987 following extensive prototyping. It was decided to adopt a digital radio interface using TDMA (Time Division Multiple Access) operating in the 900MHz frequency band. The GSM TDMA system uses 8 timeslots in a basic 200kHz carrier. GSM was designed to offer a standard set of services & features. This allows inter-operator roaming.
In 1989 the work was transferred to the European body ETSI (European Telecommunications Standards Institute). By 1990 the Phase 1 specifications were frozen. Work then started on adapting the specifications to work in the 1800MHz frequency band.
GSM Becomes a Global Standard
In 1987 a group of future GSM operators (15 operators from 13 countries) signed a Memorandum of Understanding (MoU) intending to promote the use of the GSM standard world-wide. With the change of emphasis to a world-wide standard, GSM was renamed "Global System for Mobile communications". Other countries outside Europe began to adopt the standard in particular the UAE, Hong Kong, Australia & New Zealand.
The first commercial GSM networks started service in 1991; 13 networks went live in 7 countries
The first roaming agreements were signed in 1992 and roaming started soon after. GSM was born!
General Features of the GSM Standard
The GSM standard was designed to be very flexible to allow the easy provision of services. Because there is a common standard, all GSM networks work the same way and, generally, every network can offer service to users from any other network. As a result, there is a large amount of roaming traffic and users have become used to receiving service when they travel abroad.
Another important feature of GSM is the high level of security provided. Powerful algorithms are used to authenticate users. Also, the radio interface is encrypted to a high degree of security which makes it very difficult to eavesdrop.
GSM uses a removable SIM (Subscriber Identity Module) card that holds the identity of the user. Because the SIM card can be plugged into any compatible mobile phone, users can change mobile terminals easily and take their identity with them. Also, a user’s list of names and telephone numbers can be stored on the SIM card so personal information can be transferred easily also. The SIM card has been further developed to add more processing power and memory. This allows new types of applications and operating systems to be run on the SIM that could be used by the network operator to offer customised services.
Because key interfaces are standardised, equipment from different manufacturers work together in the same network. Because all equipment works to the same specification, it is mass produced from many competing manufacturers thus lowering the cost. This also gives GSM network providers a wide choice of equipment vendors as well as the ability to “mix and match” equipment from different vendors.
Main Services Provided by the Original GSM Standard are:
Speech - Speech is digitised and good speech quality is possible in GSM's relatively low bit rate.
Data & Fax - A range of data rates up to 9600 bit/sec was standardised initially. The capability of sending and receiving Group 3 Fax was also provided. A data rate of 14.4kbit/s was later standardised.
Supplementary Services - These include Call Forwarding; Call Barring; Call Waiting, Multi-party calls; CLI (Calling Line Identification).
Short Message Service (SMS) - Text messages of up to 160 characters in length can be sent between mobile phones. Longer messages can be sent by concatenating SMS texts.
Cell Broadcast - Broadcast messages that can be customised for specific areas and for specific topics (eg weather) can be sent to all mobiles in the service area of a cell or group of cells.
Improvements to the GSM Standard in Later Standardisation Phases Included:
Better Speech Quality - New voice coders (codecs) were developed that improved speech quality and made better use of the radio capacity. These included the EFR (Enhanced Full Rate) and AMR (Adaptive Multi-Rate) codecs.
HSCSD (High Speed Circuit Switched Data) – A number of developments improved on the basic 9600bit/sec data rate provided: The HSCSD standard was developed to provide data rates greater than 64kbit/sec although in practice the rate is limited by the radio capacity and the capabilities of the mobile terminals. HSCSD gives the user dedicated multiple time slots to provide the higher rates. However, this technique is very hungry on radio resource and because multiple time slots are allocated to each user, the capacity of each radio carrier is greatly reduced. An advantage of HSCSD is that it can be used to provide “real time” services like live video because each user has dedicated resource.
GPRS (General Packet Radio Service) – This is another development intended to provide higher data rates. Like HSCSD, GPRS uses multiple time slots to increase the data throughput. Unlike HSCSD, GPRS does not allocate these slots just to one user – many users share the slots using them to send and receive data only when they need to. As a result, GPRS uses the radio resource much more efficiently than HSCSD and the capacity of the radio carrier is much higher. The way GPRS works, however, means that it cannot (currently) support “real time” services (like live video) as the user’s application cannot be guaranteed a time slot immediately when requested. The result is that variable delay is introduced to the data transmission. This makes GPRS much more suitable for “packet based” types of services such as Web browsing or downloading of data files. Practically, at present, typical rates of around 40kbit/sec (peak) can be achieved. There is scope for these rates to increase with further development of the mobile terminals and the introduction of more advanced channel coding schemes. Another feature of GPRS is that the user can set up an “always on” connection. Because the time slots are not used unless there is data to transmit, there is no overhead and the user can be permanently connected to a service such as an email server or an intranet.
EDGE (Enhanced Data for GSM Evolution) – EDGE is a modulation technique that allows each time slot on the GSM radio access to carry more data. As a result, the data rates provided by HSCSD and GPRS can be further increased. The take up of EDGE technology has been relatively small and many operators have chosen 3rd Generation systems as the route to higher data rates.
New Network Services – Some of the new services that were specified are: Multiple Subscriber Profile; Call Transfer, Calling Name Presentation and pre-pay control. Some of the new services are provided by Intelligent Network (IN) platforms (such as CAMEL) that have been introduced in the GSM core network.
Location Technologies – Basic location of the mobile can be provided by the identification of the cell and sector in use. More accurate location methods have also been developed using a variety of technologies including GPS (Global Positioning System). In some cases, it is a regulatory requirement to identify the location of the mobile for emergency calls (eg in North America).
Development of Mobile Terminals
Mobile terminals have also undergone rapid development. The early "brick-like" mobile terminals were soon superseded by more elegant models with superior performance. Battery life improved, multiple frequency bands introduced and new capabilities such as data downloading and web browsing incorporated.
More recently, many more new features have been incorporated into mobile terminals including high resolution cameras, music players, PDA (Personal Digital Assistant) and email functions and even radio and TV reception. The mobile device has become an essential "life tool" for many people.
In summary, the mobile terminal has undergone a remarkable transformation in a very short time. This has been driven by improvements in technology and manufacturing and also customer demand
A terminal that performs well and is easy to use is key to giving the user a good experience of the mobile network.
Evolution of mobile Communication:
Electromagnetic Rays were discovered as a communication medium in the 19th century. The first telephone systems offering mobile service were introduced in the late 1940s in United States and early 1950’s in Europe. Earlier cell systems were constrained with severe mobility, low capacity, limited service, and poor speech quality. Equipment was heavy, bulky, expensive, and susceptible to interference.
First Generation (1G): Analog Cellular
The introduction of cellular systems in late 1970s and early 1980s represented a quantum leap in mobile communication. 1G cellular systems transmit only analog voice information. Some prominent 1G systems are
· Advanced mobile phone systems (ADPS)
· Nordic mobile telephone (NMT)
· Total Access communication system (TACS)
Second generation (2G): multiple digital systems
The development of 2G cellular systems was driven by the need to improve transmission quality, system capacity, and coverage. Advances in Semiconductor technology brought digital transmission to mobile communication. 2G provided supplementary services apart from speech transmission like fax, short messaging servicing.
2G cellular systems include
· GSM (Global system of mobile communication)
· D-AMPS (Digital Advanced mobile phone system)
· CDMA (Code division multiple access)
· PDC (Personal digital Communication)
Today multiple 1G and 2G standards are used in worldwide mobile communication. Different standards serve levels of mobility, capability, and service area. 2G networks were launched in the early 1990s.
GSM
GSM is the most successful family of cellular standards with GSM900, GSM-R, GSM1800, GSM1900, and GSM400.
1. GSM- 900
· Uplink frequency: 890.2 MHz to 915 MHz (25 MHz)
· Downlink frequency: 935.2 MHz to 960 MHz (25 MHz
· Uplink- downlink distance: 45 MHz
It employes frequency division multiple access and Time Division Multiple Access. In FDMA each channel is 200 KHz wide and accommodates 124 pairs of channels. In TDMA each channel has 8 time slots. Hence theoretically there are 992 channels.
2. GSM –1800
· Uplink frequency: 1725.2 to 1780.4 MHz
· Downlink Frequency: 1820.2 to 1875.4 MHz
· Uplink Downlink Distance: 95 MHz
It has 384 pairs of channels.
The ubiquity of GSM makes international roaming very common between mobile operators, enabling subscribers to use mobile in any part of the world. The key advantage of GSM systems is higher digital voice quality and low cost alternatives like text messaging.
The technical fundamentals of GSM system were defined in 1987.In 1989 ETSI (European telecommunication standards institute) took over; by 1990 the first GSM specification was complete. GSM standards were enhanced in phase 2 in 1995 to incorporate large number of supplementary services. In 1996 ETSI further enhanced in GSM phase 2+ to incorporate 3G capabilities.
2.5 G (2.5 generation)
2.5 is a stepping-stone between 2G and 3G cellular wireless technologies. While 2G and 3G are officially defined, 2.5G is not. It was invented for marketing purposes only. The term "second and a half generation" is used to describe 2G-systems that have implemented a packet switched domain in addition to the circuit switched domain
2.5G provides some of the benefits of 3G (e.g. it is packet-switched) and can use some of the existing 2G infrastructure in GSM and CDMA networks.
GPRS:
Acronym for General Packet radio Service. It is an enhancement over GSM. Provides Packet oriented data service unlike Circuit switched data service in GSM in which data is split into separate but related packets. Allows IP packets to be sent and received across mobile networks.
More efficient for the network operator. Theoretical maximum speed is 171.2 Kbps using all 8-time slots. Some time slots on some frequencies are reserved for packet traffic. Base stations dynamically manage time slots.
However it has few limitations as well. It impacts network’s existing cell capacity, as the use for one purpose simultaneously precludes the use of other service. It has limited bandwidth.
EDGE
Some protocols, such as EDGE (Enhanced Data rates for GSM) and CDMA2000, can qualify as "3G" services (because they have a data rate of above 144 kbit/s), but are considered by most to be 2.5G services (or 2.75G which sounds even more sophisticated) because they are several times slower than "true" 3G services.
Acronym for Enhanced data rate for Global Evolution; it is an enhancement over GSM/GPRS. Has a data rate of 384Kbps or more. It employs FDMA/TDMA like GSM.
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3G (Third Generation)
The services associated with 3G provide the ability to transfer both voice data (a telephone call) and non-voice data (such as downloading information, exchanging email, and instanting messaging).
The first country which introduced 3G on a large commercial scale was Japan. In 2005 about 40% of subscribers use 3G networks only, and 2G is on the way out in Japan. It is expected that during 2006 the transition from 2G to 3G will be largely completed in Japan, and upgrades to the next 3.5G stage with 3 Mbit/s data rates is underway.
IMT –2000
IMT-2000 (International Mobile Teleommunications ) is the global standard for third generation(3G) wireless communication defined by ITU( International Telecommunication Union). The family of compatible standards that have the following charecteristics.
· Used world wide
· Used for all mobile applications
· Support for both Paacet Switched Transmision ans Circuit switched transmission.
· Offers high data rates of upto 2 Mbps.
· Offers high spectrum efficiency.
In the year 1998 3rd generation partenership project was establised. The original scope of 3GPP was to produce globally applicable Technical Specifications and Technical Reports for a 3rd Generation Mobile System based on evolved GSM core networks and the radio access technologies that they support (i.e., Universal Terrestrial Radio Access (UTRA) both Frequency Division Duplex (FDD) and Time Division Duplex (TDD) modes). A cooperation of standard organizations (ARIB, CWTS, ETSI, T1, TTA and TTC) throughout the world that is developing technical specification for IMT-2000.
UMTS is being developed by Third Generation Partnership project (3GPP), a joint venture of several organizations.
· ETSI (European Telecommunication Standard Institute, Europe)
· Association of Radio Industries and Business/Telecommunication Technology Committee (ARIB/TTC) (Japan),
· American National Standards Institute (ANSI) T-1 (USA)
· Telecommunications technology association (TTA) (South Korea)
· Chinese Wireless Telecommunication Standard (CWTS) (China)
To reach global acceptance, 3GPP is introducing UMTS in phases and annual releases.
IMT-2000 represents both the scheduled year for initial trial systems and frequency range of 2000 Mhz. In 1998, 17 different standards were submitted to ITU, 11 for terrestrial systems and 6 for mobile satellite systems. All 17 proposals were accepted as IMT-2000 standards.
The most important IMT-2000 proposals are UMTS (W-CDMA) as the successor of GSM, CDMA2000 and Time-division CDMA (TD-CDMA).
First Generation (1G): Analog Cellular
The introduction of cellular systems in late 1970s and early 1980s represented a quantum leap in mobile communication. 1G cellular systems transmit only analog voice information. Some prominent 1G systems are
· Advanced mobile phone systems (ADPS)
· Nordic mobile telephone (NMT)
· Total Access communication system (TACS)
Second generation (2G): multiple digital systems
The development of 2G cellular systems was driven by the need to improve transmission quality, system capacity, and coverage. Advances in Semiconductor technology brought digital transmission to mobile communication. 2G provided supplementary services apart from speech transmission like fax, short messaging servicing.
2G cellular systems include
· GSM (Global system of mobile communication)
· D-AMPS (Digital Advanced mobile phone system)
· CDMA (Code division multiple access)
· PDC (Personal digital Communication)
Today multiple 1G and 2G standards are used in worldwide mobile communication. Different standards serve levels of mobility, capability, and service area. 2G networks were launched in the early 1990s.
GSM
GSM is the most successful family of cellular standards with GSM900, GSM-R, GSM1800, GSM1900, and GSM400.
1. GSM- 900
· Uplink frequency: 890.2 MHz to 915 MHz (25 MHz)
· Downlink frequency: 935.2 MHz to 960 MHz (25 MHz
· Uplink- downlink distance: 45 MHz
It employes frequency division multiple access and Time Division Multiple Access. In FDMA each channel is 200 KHz wide and accommodates 124 pairs of channels. In TDMA each channel has 8 time slots. Hence theoretically there are 992 channels.
2. GSM –1800
· Uplink frequency: 1725.2 to 1780.4 MHz
· Downlink Frequency: 1820.2 to 1875.4 MHz
· Uplink Downlink Distance: 95 MHz
It has 384 pairs of channels.
The ubiquity of GSM makes international roaming very common between mobile operators, enabling subscribers to use mobile in any part of the world. The key advantage of GSM systems is higher digital voice quality and low cost alternatives like text messaging.
The technical fundamentals of GSM system were defined in 1987.In 1989 ETSI (European telecommunication standards institute) took over; by 1990 the first GSM specification was complete. GSM standards were enhanced in phase 2 in 1995 to incorporate large number of supplementary services. In 1996 ETSI further enhanced in GSM phase 2+ to incorporate 3G capabilities.
2.5 G (2.5 generation)
2.5 is a stepping-stone between 2G and 3G cellular wireless technologies. While 2G and 3G are officially defined, 2.5G is not. It was invented for marketing purposes only. The term "second and a half generation" is used to describe 2G-systems that have implemented a packet switched domain in addition to the circuit switched domain
2.5G provides some of the benefits of 3G (e.g. it is packet-switched) and can use some of the existing 2G infrastructure in GSM and CDMA networks.
GPRS:
Acronym for General Packet radio Service. It is an enhancement over GSM. Provides Packet oriented data service unlike Circuit switched data service in GSM in which data is split into separate but related packets. Allows IP packets to be sent and received across mobile networks.
More efficient for the network operator. Theoretical maximum speed is 171.2 Kbps using all 8-time slots. Some time slots on some frequencies are reserved for packet traffic. Base stations dynamically manage time slots.
However it has few limitations as well. It impacts network’s existing cell capacity, as the use for one purpose simultaneously precludes the use of other service. It has limited bandwidth.
EDGE
Some protocols, such as EDGE (Enhanced Data rates for GSM) and CDMA2000, can qualify as "3G" services (because they have a data rate of above 144 kbit/s), but are considered by most to be 2.5G services (or 2.75G which sounds even more sophisticated) because they are several times slower than "true" 3G services.
Acronym for Enhanced data rate for Global Evolution; it is an enhancement over GSM/GPRS. Has a data rate of 384Kbps or more. It employs FDMA/TDMA like GSM.
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3G (Third Generation)
The services associated with 3G provide the ability to transfer both voice data (a telephone call) and non-voice data (such as downloading information, exchanging email, and instanting messaging).
The first country which introduced 3G on a large commercial scale was Japan. In 2005 about 40% of subscribers use 3G networks only, and 2G is on the way out in Japan. It is expected that during 2006 the transition from 2G to 3G will be largely completed in Japan, and upgrades to the next 3.5G stage with 3 Mbit/s data rates is underway.
IMT –2000
IMT-2000 (International Mobile Teleommunications ) is the global standard for third generation(3G) wireless communication defined by ITU( International Telecommunication Union). The family of compatible standards that have the following charecteristics.
· Used world wide
· Used for all mobile applications
· Support for both Paacet Switched Transmision ans Circuit switched transmission.
· Offers high data rates of upto 2 Mbps.
· Offers high spectrum efficiency.
In the year 1998 3rd generation partenership project was establised. The original scope of 3GPP was to produce globally applicable Technical Specifications and Technical Reports for a 3rd Generation Mobile System based on evolved GSM core networks and the radio access technologies that they support (i.e., Universal Terrestrial Radio Access (UTRA) both Frequency Division Duplex (FDD) and Time Division Duplex (TDD) modes). A cooperation of standard organizations (ARIB, CWTS, ETSI, T1, TTA and TTC) throughout the world that is developing technical specification for IMT-2000.
UMTS is being developed by Third Generation Partnership project (3GPP), a joint venture of several organizations.
· ETSI (European Telecommunication Standard Institute, Europe)
· Association of Radio Industries and Business/Telecommunication Technology Committee (ARIB/TTC) (Japan),
· American National Standards Institute (ANSI) T-1 (USA)
· Telecommunications technology association (TTA) (South Korea)
· Chinese Wireless Telecommunication Standard (CWTS) (China)
To reach global acceptance, 3GPP is introducing UMTS in phases and annual releases.
IMT-2000 represents both the scheduled year for initial trial systems and frequency range of 2000 Mhz. In 1998, 17 different standards were submitted to ITU, 11 for terrestrial systems and 6 for mobile satellite systems. All 17 proposals were accepted as IMT-2000 standards.
The most important IMT-2000 proposals are UMTS (W-CDMA) as the successor of GSM, CDMA2000 and Time-division CDMA (TD-CDMA).
UMTS Network Architecture
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• UMTS network architecture consists of three domains:
– Core Network (CN) : To provide switching, routing and transit for user traffic.
– UMTS Terrestrial Radio Access Network (UTRAN) : Provides the air interface access method for User Equipment.
– User Equipment (UE) : Terminals work as air interface counterpart for Node B. The various identities are: IMSI, TMSI, P-TMSI, TLLI, MSISDN, IMEI, IMEISV.
– Core Network (CN) : To provide switching, routing and transit for user traffic.
– UMTS Terrestrial Radio Access Network (UTRAN) : Provides the air interface access method for User Equipment.
– User Equipment (UE) : Terminals work as air interface counterpart for Node B. The various identities are: IMSI, TMSI, P-TMSI, TLLI, MSISDN, IMEI, IMEISV.
Introduction of UMTS
Standing for "Universal Mobile Telecommunications System", UMTS represents an evolution in terms of capacity, data speeds and new service capabilities from second generation mobile networks.Today, more than 60 3G/UMTS networks using WCDMA technology are operating commercially in 25 countries, supported by a choice of over 100 terminal designs from Asian, European and US manufacturers. Japanese operator NTT DoCoMo launched the world's first commercial WCDMA network in 2001.A key member of the global family of third generation (3G) mobile technologies identified by the ITU, 3G/UMTS offers mobile operators significant capacity and broadband capabilities to support greater numbers of voice and data customers - especially in urban centres - plus higher data rates at lower incremental cost than 2G. Making use of radio spectrum in bands identified by the ITU for Third Generation IMT-2000 mobile services and subsequently licensed to operators, 3G/UMTS employs a 5 MHz channel carrier width to deliver significantly higher data rates and increased capacity compared with second generation networks. This 5 MHz channel carrier provides optimum use of radio resources, especially for operators who have been granted large, contiguous blocks of spectrum - typically ranging from 2x10 MHz up to 2x20 MHz - to reduce the cost of deploying 3G networks. Crucially, 3G/UMTS has been specified as an integrated solution for mobile voice and data with wide area coverage. Universally standardised via the Third Generation Partnership Project (www.3gpp.org) and using globally harmonised spectrum in paired and unpaired bands, 3G/UMTS in its initial phase offers theoretical bit rates of up to 384 kbps in high mobility situations, rising as high as 2 Mbps in stationary/nomadic user environments. Symmetry between uplink and downlink data rates when using paired (FDD) spectrum also means that 3G/UMTS is ideally suited for applications such as real-time video telephony - in contrast with other technologies such as ADSL where there is a pronounced asymmetry between uplink and downlink throughput rates.Specified and implemented as an end-to-end mobile system, 3G/UMTS also features the additional benefits of automatic international roaming plus integral security and billing functions, allowing operators to migrate from 2G to 3G while retaining many of their existing back-office systems. Offering increased capacity and speed at lower incremental cost compared with second generation mobile systems, 3G/UMTS gives operators the flexibility to introduce new multimedia services to business users and consumers while providing an enhanced user experience. This in turn provides the opportunity for operators to build on the brand-based relationships they already enjoy with their customers - and drive new revenue opportunities by encouraging additional traffic, stimulating new usage patterns and strengthening customer loyalty.Ongoing technical work within 3GPP will see further increases in throughput speeds of the WCDMA Radio Access Network (RAN). High Speed Downlink Packet Access (HSDPA) and High Speed Uplink Packet Access (HSUPA) technologies are already standardised and are undergoing network trials with operators in the Far East and North America. Promising theoretical downlink speeds as high as 14.4 Mbps (and respectively 5.8 Mbps uplink), these technologies will play an instrumental role in positioning 3G/UMTS as a key enabler for true 'mobile broadband'. Offering data transmission speeds of the same order of magnitude as today's Ethernet-based networks that are a ubiquitous feature of the fixed-line environment, 3G/UMTS will offer enterprise customers and consumers all the benefits of broadband connectivity whilst on the move.
3G - Mobile Evolution
Third Generation mobile in the shape of UMTS (Universal Mobile Telecommunications System) with WCDMA (Wideband Code Division Multiple Access) as radio access technology is already a reality.With the first European networks already live and an increasing number of commercial launches anticipated during 2003, UMTS/WCDMA offers business users and consumers an evolution of their current mobile experience to add video and other exciting new services.Approaching 120 licenses have already been awarded to operators worldwide, specifying WCDMA radio access technology that builds on GSM to provide a clear evolutionary path for more than 80% of the world's wireless market.In terms of initial capital expenditure as well as ongoing operational costs, WCDMA technology offers new and existing operators alike a more economical platform to cope with projected growth in demand for voice and data services.For customers already enjoying voice and data services via 2G and 2.5G, UMTS/WCDMA delivers even more of what they like doing already... faster, more efficiently and with new possibilities. For many of the 1.2 billion customers of second generation networks, UMTS is Third Generation mobile.What are the implications of this continued growth in mobile subscriptions, the changing mix of voice and data revenues and the proliferation of new mobile terminal devices?To address some of these questions, this section provides an overview of the market, technology, regulatory and service issues faced by network operators and manufacturers as well as the developers of mobile applications as they prepare their own 3G customer offerings.In particular, it considers the benefits to industry and end users of a roadmap to and evolution of UMTS/WCDMA as part of the ITU/IMT-2000 standard.
3G - Mobile Evolution
Third Generation mobile in the shape of UMTS (Universal Mobile Telecommunications System) with WCDMA (Wideband Code Division Multiple Access) as radio access technology is already a reality.With the first European networks already live and an increasing number of commercial launches anticipated during 2003, UMTS/WCDMA offers business users and consumers an evolution of their current mobile experience to add video and other exciting new services.Approaching 120 licenses have already been awarded to operators worldwide, specifying WCDMA radio access technology that builds on GSM to provide a clear evolutionary path for more than 80% of the world's wireless market.In terms of initial capital expenditure as well as ongoing operational costs, WCDMA technology offers new and existing operators alike a more economical platform to cope with projected growth in demand for voice and data services.For customers already enjoying voice and data services via 2G and 2.5G, UMTS/WCDMA delivers even more of what they like doing already... faster, more efficiently and with new possibilities. For many of the 1.2 billion customers of second generation networks, UMTS is Third Generation mobile.What are the implications of this continued growth in mobile subscriptions, the changing mix of voice and data revenues and the proliferation of new mobile terminal devices?To address some of these questions, this section provides an overview of the market, technology, regulatory and service issues faced by network operators and manufacturers as well as the developers of mobile applications as they prepare their own 3G customer offerings.In particular, it considers the benefits to industry and end users of a roadmap to and evolution of UMTS/WCDMA as part of the ITU/IMT-2000 standard.
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