In telecommunications, 4G is the fourth generation of cellular wireless standards. It is a successor of the 3G and 2G families of standards. In 2009, the ITU-R organization specified the IMT-Advanced (International Mobile Telecommunications Advanced) requirements for 4G standards, setting peak speed requirements for 4G service at 100 Mbit/s for high mobility communication (such as from trains and cars) and 1 Gbit/s for low mobility communication (such as pedestrians and stationary users).
The world’s first publicly available LTE service was opened in the two Scandinavian capitals Stockholm (Ericsson and Nokia Siemens Networks systems) and Oslo (a Huawei system) on 14 December 2009.
One of the key technologies for 4G and beyond is called Open Wireless Architecture (OWA), supporting multiple wireless air interfaces in an open architecture platform.
A 4G system is expected to provide a comprehensive and secure all-internet protocol (IP) based mobile broadband solution to laptop computer wireless modems, smartphones, and other mobile devices. Facilities such as ultra-broadband Internet access, IP telephony, gaming services, and streamed multimedia may be provided to users.
IMT-Advanced compliant versions of LTE and WiMAX are under development and called “LTE Advanced” and “WirelessMAN-Advanced” respectively. ITU has decided that LTE Advanced and WirelessMAN-Advanced should be accorded the official designation of IMT-Advanced. On December 6, 2010, ITU recognized that current versions of LTE, WiMax and other evolved 3G technologies that do not fulfill “IMT-Advanced” requirements could nevertheless be considered “4G”, provided they represent forerunners to IMT-Advanced and “a substantial level of improvement in performance and capabilities with respect to the initial third generation systems now deployed.”
As seen below, in all suggestions for 4G, the CDMA spread spectrum radio technology used in 3G systems and IS-95 is abandoned and replaced by OFDMA and other frequency-domain equalization schemes. This is combined with multiple in multiple out (MIMO), e.g., multiple antennas, dynamic channel allocation and channel-dependent scheduling.
The nomenclature of the generations generally refers to a change in the fundamental nature of the service, non-backwards-compatible transmission technology, higher spectral bandwidth and new frequency bands. New generations have appeared about every ten years since the first move from 1981 analog (1G) to digital (2G) transmission in 1992. This was followed, in 2001, by 3G multi-media support, spread spectrum transmission and at least 200 kbit/s, in 2011 expected to be followed by 4G, which refers to all-Internet Protocol (IP) packet-switched networks, mobile ultra-broadband (gigabit speed) access and multi-carrier transmission.
The fastest 3G-based standard in the WCDMA family is the HSPA+ standard, which was commercially available in 2009 and offers 28 Mbit/s downstreams (22 Mbit/s upstreams) without MIMO, i.e. only with one antenna, and in 2011 accelerated up to 42 Mbit/s peak bit rate downstreams using 2×2 MIMO. The fastest 3G-based standard in the CDMA2000 family is the EV-DO Rev. B, which was available in 2010 and offers 15.67 Mbit/s downstreams.
In mid 1990s, the ITU-R organization released the IMT-2000 specifications for what standards should be considered 3G systems. However, the cell phone market considers only some of the IMT-2000 standards as 3G (e.g., WCDMA and CDMA2000). (3GPP EDGE, DECT and mobile-WiMAX fulfill all IMT-2000 requirements and are formally accepted as 3G standards, but are typically not branded as 3G). In 2008, ITU-R specified the IMT-Advanced (International Mobile Telecommunications Advanced) requirements for 4G systems.
This article uses 4G to refer to IMT-Advanced (International Mobile Telecommunications Advanced), as defined by ITU-R. An IMT-Advanced cellular system must fulfill the following requirements:
- Based on an all-IP packet switched network.
- Peak data rates of up to approximately 100 Mbit/s for high mobility such as mobile access and up to approximately 1 Gbit/s for low mobility such as nomadic/local wireless access.
- Dynamically share and use the network resources to support more simultaneous users per cell.
- Scalable channel bandwidth 5–20 MHz, optionally up to 40 MHz.
- Peak link spectral efficiency of 15 bit/s/Hz in the downlink, and 6.75 bit/s/Hz in the uplink (meaning that 1 Gbit/s in the downlink should be possible over less than 67 MHz bandwidth).
- System spectral efficiency of up to 3 bit/s/Hz/cell in the downlink and 2.25 bit/s/Hz/cell for indoor usage.
- Smooth handovers across heterogeneous networks.
- Ability to offer high quality of service for next generation multimedia support.
In September 2009, the technology proposals were submitted to the International Telecommunication Union (ITU) as 4G candidates. Basically all proposals are based on two technologies:
- LTE Advanced standardized by the 3GPP
- 802.16m standardized by the IEEE (i.e. WiMAX)
Present implementations of WiMAX and LTE are largely considered a stopgap solution that will offer a considerable boost until WiMAX 2 (based on the 802.16m spec) and LTE Advanced are finalized. Both technologies aim to reach the objectives given by the ITU, but are still far from being implemented.
The first set of 3GPP requirements on LTE Advanced was approved in June 2008. LTE Advanced was to be standardized in 2010 as part of Release 10 of the 3GPP specification. LTE Advanced will be based on the existing LTE specification Release 10 and will not be defined as a new specification series. A summary of the technologies that have been studied as the basis for LTE Advanced is included in a technical report.
Current LTE and WiMAX implementations are considered pre-4G, as they do not fully comply with the planned requirements of 1 Gbit/s for stationary reception and 100 Mbit/s for mobile.
Confusion has been caused by some mobile carriers who have launched products advertised as 4G but which are actually current technologies, commonly referred to as ‘3.9G’, which do not follow the ITU-R defined principles for 4G standards. A common argument for branding 3.9G systems as new-generation is that they use different frequency bands from 3G technologies; that they are based on a new radio-interface paradigm; and that the standards are not backwards compatible with 3G, whilst some of the standards are expected to be forwards compatible with “real” 4G technologies.
While the ITU has adopted recommendations for technologies that would be used for future global communications, they do not actually perform the standardization or development work themselves, instead relying on the work of other standards bodies such as IEEE, The WiMAX Forum and 3GPP. Recently, ITU-R Working Party 5D approved two industry-developed technologies (LTE Advanced and WirelessMAN-Advanced) for inclusion in the ITU’s International Mobile Telecommunications Advanced (IMT-Advanced program), which is focused on global communication systems that would be available several years from now
Objectives of 4G
4G is being developed to accommodate the quality of service (QoS) and rate requirements set by further development of existing 3G applications like mobile broadband access, Multimedia Messaging Service (MMS), video chat, mobile TV, but also new services like HDTV. 4G may allow roaming with wireless local area networks, and may interact with digital video broadcasting systems.
In the literature, the assumed or expected 4G requirements have changed during the years before IMT-Advanced was specified by the ITU-R. These are examples of objectives stated in various sources:
- A nominal data rate of 100 Mbit/s while the client physically moves at high speeds relative to the station, and 1 Gbit/s while client and station are in relatively fixed positions as defined by the ITU-R
- A data rate of at least 100 Mbit/s between any two points in the world
- Smooth handoff across heterogeneous networks
- Seamless connectivity and global roaming across multiple networks
- High quality of service for next generation multimedia support (real time audio, high speed data, HDTV video content, mobile TV, etc.)
- Interoperability with existing wireless standards
- An all IP, packet switched network
- IP-based femtocells (home nodes connected to fixed Internet broadband infrastructure)
- Physical layer transmission techniques are as follows:
- MIMO: To attain ultra high spectral efficiency by means of spatial processing including multi-antenna and multi-user MIMO
- Frequency-domain-equalization, for example multi-carrier modulation (OFDM) in the downlink or single-carrier frequency-domain-equalization (SC-FDE) in the uplink: To exploit the frequency selective channel property without complex equalization
- Frequency-domain statistical multiplexing, for example (OFDMA) or (single-carrier FDMA) (SC-FDMA, a.k.a. linearly precoded OFDMA, LP-OFDMA) in the uplink: Variable bit rate by assigning different sub-channels to different users based on the channel conditions
- Turbo principle error-correcting codes: To minimize the required SNR at the reception side
- Channel-dependent scheduling: To use the time-varying channel
- Link adaptation: Adaptive modulation and error-correcting codes
- Relaying, including fixed relay networks (FRNs), and the cooperative relaying concept, known as multi-mode protocol
4G features assumed in early literature
The 4G system was originally envisioned by the Defense Advanced Research Projects Agency (DARPA). The DARPA selected the distributed architecture and end-to-end Internet protocol (IP), and believed at an early stage in peer-to-peer networking in which every mobile device would be both a transceiver and a router for other devices in the network, eliminating the spoke-and-hub weakness of 2G and 3G cellular systems. Since the 2.5G GPRS system, cellular systems have provided dual infrastructures: packet switched nodes for data services, and circuit switched nodes for voice calls. In 4G systems, the circuit-switched infrastructure is abandoned and only a packet-switched network is provided, while 2.5G and 3G systems require both packet-switched and circuit-switched network nodes, i.e. two infrastructures in parallel. This means that in 4G, traditional voice calls are replaced by IP telephony.
Cellular systems such as 4G allow seamless mobility; thus a file transfer is not interrupted in case a terminal moves from one cell (one base station coverage area) to another, but handover is carried out. The terminal also keeps the same IP address while moving, meaning that a mobile server is reachable as long as it is within the coverage area of any server. In 4G systems this mobility is provided by the mobile IP protocol, part of IP version 6, while in earlier cellular generations it was provided only by physical-layer and datalink-layer protocols. In addition to seamless mobility, 4G provides flexible interoperability of the various kinds of existing wireless networks, such as satellite, cellular wireless, WLAN, PAN and systems for accessing fixed wireless networks.
While maintaining seamless mobility, 4G will offer very high data rates with expectations of 100 Mbit/s wireless service. The increased bandwidth and higher data transmission rates will allow 4G users the ability to use high-definition video and the videoconferencing features of mobile devices attached to a 4G network. The 4G wireless system is expected to provide a comprehensive IP solution where multimedia applications and services can be delivered to the user on an ‘anytime, anywhere’ basis with a satisfactory high data rate, premium quality and high security.
4G is described as MAGIC: mobile multimedia, anytime anywhere, global mobility support, integrated wireless solution, and customized personal service. Some key features (primarily from users’ points of view) of 4G mobile networks are:
- High usability: anytime, anywhere, and with any technology
- Support for multimedia services at low transmission cost
- Integrated services
History of 4G and pre-4G technologies
As of December 2011, there are no 4G networks that fulfil the International Telecommunication Union’s criteria of being able to achieve 1Gbit/s while stationary.
However in December 2010, the ITU recognized that current versions of LTE, WiMax and other evolved 3G technologies that do not fulfill “IMT-Advanced” requirements could nevertheless be considered “4G”, provided they represent forerunners to IMT-Advanced and “a substantial level of improvement in performance and capabilities with respect to the initial third generation systems now deployed.”
- In 2002, the strategic vision for 4G—which ITU designated as IMT-Advanced—was laid out.
- In 2005, OFDMA transmission technology is chosen as candidate for the HSOPA downlink, later renamed 3GPP Long Term Evolution (LTE) air interface E-UTRA.
- In November 2005, KT demonstrated mobile WiMAX service in Busan, South Korea.
- In April 2006, KT started the world’s first commercial mobile WiMAX service in Seoul, South Korea.
- In mid-2006, Sprint Nextel announced that it would invest about US$5 billion in a WiMAX technology buildout over the next few years ($5.76 billion in real terms). Since that time Sprint has faced many setbacks, that have resulted in steep quarterly losses. On May 7, 2008, Sprint, Imagine, Google, Intel, Comcast, Bright House, and Time Warner announced a pooling of an average of 120 MHz of spectrum; Sprint merged its Xohm WiMAX division with Clearwire to form a company which will take the name “Clear”.
- In February 2007, the Japanese company NTT DoCoMo tested a 4G communication system prototype with 4×4 MIMO called VSF-OFCDM at 100 Mbit/s while moving, and 1 Gbit/s while stationary. NTT DoCoMo completed a trial in which they reached a maximum packet transmission rate of approximately 5 Gbit/s in the downlink with 12×12 MIMO using a 100 MHz frequency bandwidth while moving at 10 km/h, and is planning on releasing the first commercial network in 2010.
- In September 2007, NTT Docomo demonstrated e-UTRA data rates of 200 Mbit/s with power consumption below 100 mW during the test.
- In January 2008, a U.S. Federal Communications Commission (FCC) spectrum auction for the 700 MHz former analog TV frequencies began. As a result, the biggest share of the spectrum went to Verizon Wireless and the next biggest to AT&T. Both of these companies have stated their intention of supporting LTE.
- In January 2008, EU commissioner Viviane Reding suggested re-allocation of 500–800 MHz spectrum for wireless communication, including WiMAX.
- On 15 February 2008 – Skyworks Solutions released a front-end module for e-UTRAN.
- In 2008, ITU-R established the detailed performance requirements of IMT-Advanced, by issuing a Circular Letter calling for candidate Radio Access Technologies (RATs) for IMT-Advanced.
- In April 2008, just after receiving the circular letter, the 3GPP organized a workshop on IMT-Advanced where it was decided that LTE Advanced, an evolution of current LTE standard, will meet or even exceed IMT-Advanced requirements following the ITU-R agenda.
- In April 2008, LG and Nortel demonstrated e-UTRA data rates of 50 Mbit/s while travelling at 110 km/h.
- On 12 November 2008, HTC announced the first WiMAX-enabled mobile phone, the Max 4G
- In December 2008, San Miguel Corporation, southeast Asia’s largest food and beverage conglomerate, has signed a memorandum of understanding with Qatar Telecom QSC (Qtel) to build wireless broadband and mobile communications projects in the Philippines. The joint-venture formed wi-tribe Philippines, which offers 4G in the country. Around the same time Globe Telecom rolled out the first WiMAX service in the Philippines.
- On 3 March 2009, Lithuania’s LRTC announcing the first operational “4G” mobile WiMAX network in Baltic states.
- In December 2009, Sprint began advertising “4G” service in selected cities in the United States, despite average download speeds of only 3–6 Mbit/s with peak speeds of 10 Mbit/s (not available in all markets).
- On 14 December 2009, the first commercial LTE deployment was in the Scandinavian capitals Stockholm and Oslo by the Swedish-Finnish network operator TeliaSonera and its Norwegian brandname NetCom (Norway). TeliaSonera branded the network “4G”. The modem devices on offer were manufactured by Samsung (dongle GT-B3710), and the network infrastructure created by Huawei (in Oslo) and Ericsson (in Stockholm). TeliaSonera plans to roll out nationwide LTE across Sweden, Norway and Finland. TeliaSonera used spectral bandwidth of 10 MHz, and single-in-single-out, which should provide physical layer net bitrates of up to 50 Mbit/s downlink and 25 Mbit/s in the uplink. Introductory tests showed a TCP throughput of 42.8 Mbit/s downlink and 5.3 Mbit/s uplink in Stockholm.
- On 25 February 2010, Estonia’s EMT opened LTE “4G” network working in test regime.
- On 4 June 2010, Sprint Nextel released the first WiMAX smartphone in the US, the HTC Evo 4G.
- In July 2010, Uzbekistan’s MTS deployed LTE in Tashkent.
- On 25 August 2010, Latvia’s LMT opened LTE “4G” network working in test regime 50% of territory.
- On 6 December 2010, at the ITU World Radiocommunication Seminar 2010, the ITU stated that LTE, WiMax and similar “evolved 3G technologies” could be considered “4G”.
- On 12 December 2010, VivaCell-MTS launches in Armenia 4G/LTE commercial test network with a live demo conducted in Yerevan.
- On 28 April 2011, Lithuania’s Omnitel opened LTE “4G” network working in 5 biggest cities.
- In September 2011, All three Saudi telecom giants STC, Mobily and Zain announced that they will offer 4G LTE for high speed USB sticks for mobile computers, with further development for telephones by 2013.
- In 2011, Argentina´s Claro launch 4G HSPA+ network in the country.
- In 2011, Thailand’s Truemove-H launch 4G HSPA+ network with nation-wide availability.
- On 31 January 2012, Thailand’s AIS and its subsidiaries DPC under co-operative with CAT Telecom for 1800 MHz frequency band and TOT for 2300 MHz frequency band launch the first field trial LTE in Thailand by authorization from NBTC
In May 2005, Digiweb, an Irish fixed and wireless broadband company based in Ireland, announced that they had received a mobile communications license from the Irish Telecoms regulator, ComReg. This service will be issued the mobile code 088 in Ireland and will be used for the provision of 4G Mobile communications. Digiweb launched a mobile broadband network using FLASH-OFDM technology at 872 MHz.
On September 20, 2007, Verizon Wireless announced plans for a joint effort with the Vodafone Group to transition its networks to the 4G standard LTE. On December 9, 2008, Verizon Wireless announced their intentions to build and begin to roll out an LTE network by the end of 2009. Since then, Verizon Wireless has said that they will start their rollout by the end of 2010.
On July 7, 2008, South Korea announced plans to spend 60 billion won, or US$58,000,000, on developing 4G and even 5G technologies, with the goal of having the highest mobile phone market share by 2012, and the hope of an international standard.
Telus and Bell Canada, the major Canadian cdmaOne and EV-DO carriers, have announced that they will be cooperating towards building a fourth generation (4G) LTE wireless broadband network in Canada. As a transitional measure, they are implementing 3G UMTS that went live in November 2009.
Sprint Nextel offers a 3G/4G connection plan, currently available in select cities in the United States. It delivers rates up to 10 Mbit/s. Sprint has announced that they will launch a LTE network in early 2012.
In the United Kingdom and in Ireland, O2 UK and O2 (Ireland) (part of Telefónica O2) are to use Slough as a guinea pig in testing the 4G network and has called upon Huawei to install LTE technology in six masts across the town to allow people to talk to each other via HD video conferencing and play PlayStation games while on the move.
Verizon Wireless has announced that it plans to augment its CDMA2000-based EV-DO 3G network in the United States with LTE, and is supposed to complete a rollout of 175 cities by the end of 2011, two thirds of the US population by mid-2012, and cover the existing 3G network by the end of 2013. AT&T, along with Verizon Wireless, has chosen to migrate toward LTE from 2G/GSM and 3G/HSPA by 2011.
Sprint Nextel has deployed WiMAX technology which it has labeled 4G as of October 2008. It is currently deploying to additional markets and is the first US carrier to offer a WiMAX phone.
The U.S. FCC is exploring the possibility of deployment and operation of a nationwide 4G public safety network which would allow first responders to seamlessly communicate between agencies and across geographies, regardless of devices. In June 2010 the FCC released a comprehensive white paper which indicates that the 10 MHz of dedicated spectrum currently allocated from the 1700 MHz spectrum for public safety will provide adequate capacity and performance necessary for normal communications as well as serious emergency situations.
TeliaSonera started deploying LTE (branded “4G”) in Stockholm and Oslo November 2009 (as seen above), and in several Swedish, Norwegian, and Finnish cities during 2010. In June 2010, Swedish television companies used 4G to broadcast live television from the Swedish Crown Princess’ Royal Wedding.
Safaricom, a telecommunication company in East& Central Africa, began its setup of a 4G network in October 2010 after the now retired& Kenya Tourist Board Chairman, Michael Joseph, regarded their 3G network as a white elephant i.e. it failed to perform to expectations. Huawei was given the contract the network is set to go fully commercial by the end of Q1 of 2011
Telstra announced on 15 February 2011, that it intends to upgrade its current Next G network to 4G with Long Term Evolution (LTE) technology in the central business districts of all Australian capital cities and selected regional centers by the end of 2011.
Sri Lanka Telecom Mobitel and Dialog Axiata announced that first time in South Asia Sri Lanka have successfully tested and demonstrated 4G technology on 6 May 2011(Sri Lanka Telecom Mobitel) and 7 May 2011(Dialog Axiata) and began the setup of their 4G Networks in Sri Lanka.
On May 2011, Brazil’s Communication Ministry announced that the 12 host cities for the 2014 FIFA World Cup to be held there will be the first to have their networks upgraded to 4G. Mobitel was able to reach 96Mbit/s of speed while Dialog Axiata reached 128Mbit/s on their demonstration.
In mid September 2011,
Mobily of Saudi Arabia, announced their 4G LTE networks to be ready after months of testing and evaluations.
On September 2011, UAE’s Etisalat announced commercial launch of 4G LTE services covering over 70% of country’s urban areas.
India is expected to see launch of 4G services using TD-LTE technology in January 2012. The services will be launched by Augere, a UK based company, in Madhya Pradesh and Chhattisgarh under the Zoosh brand name.
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