Friday, April 13, 2007

4G (Fourth Generation)

4G is short for fourth-generation cellular communication system. There is no set definition to what 4G is, however the features that are predicted for 4G can be summarized in a single sentence:

The 4G will be a fully IP-based integrated system of systems and network of networks achieved after the convergence of wired and wireless networks as well as computer, consumer electronics, communication technology, and several other convergences that will be capable of providing 100 Mbps and 1Gbps, respectively, in outdoor and indoor environments with end-to-end QoS and high security, offering any kind of services anytime, anywhere, at affordable cost and one billing.[1]

The Wireless World Research Forum (WWRF) defines 4G as a network that operates on Internet technology, combines it with other applications and technologies such as Wi-Fi and WiMAX, and runs at speeds ranging from 100 Mbps (in cell-phone networks) to 1 Gbps (in local Wi-Fi networks).[2] 4G is not just one defined technology or standard, but rather a collection of technologies and protocols to enable the highest throughput, lowest cost wireless network possible.[3]

Contents

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Objectives

To cater the quality of service and rate requirements set by the forthcoming applications like wireless broadband access, Multimedia Messaging Service, video chat, mobile TV, High definition TV content, DVB and minimal service like voice and data at anytime and anywhere 4G is being developed , the 4G working groups have defined the following as the objectives of the 4G wireless communication standard

  • High network capacity[5]
  • Nominal data rate of 100 Mbps at high speeds and 1 Gbps at stationary conditions as defined by the ITU-R[1]
  • Data rate of at least 100 Mbps between any two points in the world[1]
  • Seamless connectivity and global roaming across multiple networks[7]
  • High quality of service for next generation multimedia support (real time audio, high speed data, HDTV video content, mobile TV, etc)[7]
  • Interoperable with the existing wireless standards[8]
  • All IP system, packet switched network[7]

In summary, the 4G system should dynamically share and utilise the network resource to meet the minimal requirements of all the 4G enabled users.

Evolution

First generation: Almost all of the systems from this generation were analog systems where voice was considered to be the main traffic. These systems could often be listened to by third parties. some of the standards are NMT, AMPS, Hicap, CDPD, Mobitex, DataTac

Second generation: All the standards belonging to this generation are commercial centric and they are digital in form. Around 60% of the current market is dominated by European standards. The second generation standards are GSM, iDEN, D-AMPS, IS-95, PDC, CSD, PHS, GPRS, HSCSD, WiDEN and CDMA2000 (1xRTT/IS-2000).

Third generation: To meet the growing demands in the number of subscribers (increase in network capacity), rates required for high speed data transfer and multimedia applications 3G standards started evolving. The systems in this standard are basically a linear enhancement of 2G systems. They are based on two parallel backbone infrastructures, one consisting of circuit switched nodes, and one of packet oriented nodes. Currently, transition is happening from 2G to 3G systems. Some of the 3G standards are EDGE and EGPRS (sometimes denoted 2.75G), W-CDMA or UMTS (3GSM), FOMA, 1xEV-DO/IS-856, TD-SCDMA, GAN/UMA, 3.5G - HSDPA, 3.75G - HSUPA. The ITU defines a specific set of air interface technologies as third generation, as part of the IMT-2000 initiative.

Fourth generation: According to 4G working groups, the infrastructure and the terminals will have almost all the standards from 2G to 3G implemented. The infrastructure will however only be packet based, all-IP. The system will also serve as an open platform where the new innovations can go with it. Some of the standards which pave the way for 4G systems are WiMax, WiBro, and the proposed 3GPP Long Term Evolution work-in-progress technologies such as HSOPA.

Components

Access schemes

The existing wireless standards use TDMA, FDMA, CDMA and combinations of these to multiplex multiple mobile stations (handsets, etc) use of spectrum, with CDMA (IS-2000, W-CDMA, TD-CDMA, TD-SCDMA) dominating the 3G space. However, all these technologies are limited; TDMA suffers from inherent inefficiencies due to the need for guard periods between frames, and CDMA from poor spectrum flexibility and scalability.

Recently, new access schemes like OFDMA, Single Carrier FDMA, and MC-CDMA have been proposed as part of the upcoming next generation UMTS, 802.16e and 802.20 standards. These offer the same efficiencies as older technologies like CDMA, but offer advantages in scalability.

In addition to improvements in these multiplexing systems, improved modulation techniques are being used. Whereas earlier standards largely used Phase-shift keying, more efficient systems such as 64QAM are being proposed for use with the 3GPP Long Term Evolution standards.

IPv6

Unlike the 3G networks which are a jumble of circuit switched and packet switched networks, 4G will be based on packet switching only. This will require low-latency data transmission.

It is generally believed that 4th generation wireless networks would support a great number of wireless devices that are addressable and routable. Therefore in the context of 4G, IPv6 is an important network layer technology and standard that can support a great number of wireless enabled devices. By increasing the number of IP addresses, IPv6 removes the need for Network Address Translation (NAT), a current workaround used to mitigate the dwindling number of IPv4 addresses.

In the context of 4G, IPv6 also enables a number of applications with better multi-cast, security and route optimization capabilities. With the available address space and number of addressing bits in IPv6, many innovative coding schemes can be developed for 4G devices and applications that could aid deployment of 4G networks and services.

Multi-Antenna Systems

In the early 90s, to cater the growing data rate needs of data communication, many transmission schemes were proposed. One technology, spatial multiplexing, gained importance for its bandwidth conservation and power efficiency. Spatial multiplexing involves deploying multiple antennas at the transmitter and at the receiver. Independent streams can be transmitted simultaneously from all the antennas. This increases the data rate into multiple folds with the number equal to minimum of the number of transmit and receive antennas. This is called as Multiple-input multiple-output communications (MIMO). Apart from this, the reliability in transmitting high speed data in the fading channel can be improved by using more antennas at the transmitter or at the receiver. This is called transmit or receive diversity.

Software-Defined Radio (SDR)

SDR is one form of open wireless architecture (OWA). Since 4G is the collection of wireless standards, the final form of the 4G device will constitute all standards. This can be realized using SDR technology.

Developments

The Japanese company NTT DoCoMo has been testing a 4G communication system prototype called VSF-OFCDM at 100 Mbit/s while moving, and 1 Gbit/s while stationary. NTT DoCoMo recently reached 5 Gbit/s while moving at 10 km/h,[9] and is planning on releasing the first commercial network in 2010.

Pervasive networks an amorphous and presently entirely hypothetical concept where the user can be simultaneously connected to several wireless access technologies and can seamlessly move between them (See handover, IEEE 802.21). These access technologies can be Wi-Fi, UMTS, EDGE or any other future access technology. Included in this concept is also smart-radio (also known as cognitive radio technology) to efficiently manage spectrum use and transmission power as well as the use of mesh routing protocols to create a pervasive network.

Sprint plans to launch 4G services in trial markets by the end of 2007 with plans to deploy a network that reaches as many as 100 million people in 2008.

The German WiMAX operator Deutsche Breitband Dienste (DBD) has launched WiMAX services in Magdeburg and Dessau. The subscribers are offered two tariff plans. The first costing $12.99 per month offering 1 Mbit/s connection speed and 1 GB monthly traffic. The second plan has unlimited traffic, the speed increased to 2 Mbit/s for a $25.99 monthly fee. The subscribers are also charged $90.99 for the equipment and installation.[10] DBD received additional national licenses for WiMAX in December 2006 and have already launched the services in Berlin, Leipzig and Dresden.

American WiMAX services provider Clearwire made its debut on Nasdaq in New York on March 8, 2007. The IPO was underwritten by Merrill Lynch, Morgan Stanley and JP Morgan. Clearwire sold 24 million shares at a price of $25 per share. This adds $600 million in cash to Clearwire, and gives the company a market valuation of just over $3.9 billion.[11]

Applications

The killer application of 4G is not clear, though the improved bandwidths and data throughput offered by 4G networks should provide opportunities for previously impossible products and services to be released.

Already at rates of 15-30 Mbps, 4G should be able to provide users with streaming high-definition television. At rates of 100 Mbps, the content of a DVD, for example a movie, can be downloaded within about 5 minutes for offline access.

Market position

According to a Visant Strategies study there will be multiple competitors in this space, and gave the following projections:[12]

References

  1. ^ a b c Young Kyun, Kim; Prasad, Ramjee. 4G Roadmap and Emerging Communication Technologies. Artech House, pp 12-13. ISBN 1-58053-931-9.
  2. ^ William Boston (Oct. 05, 2003). Is 4G The Future?. Time magazine. Retrieved on 2007 March 26.
  3. ^ 4G. Infocomm Development Authority of Singapore. Retrieved on 2006 November 20.
  4. ^ 4G - Beyond 2.5G and 3G Wireless Networks. MobileInfo.com. Retrieved on 2007 March 26.
  5. ^ Jawad Ibrahim (December 2002). 4G Features. Bechtel Telecommunications Technical Journal. Retrieved on 2007 March 26.
  6. ^ Mobility Management Challenges and Issues in 4G Heterogeneous Networks. ACM Proceedings of the first international conference on Integrated internet ad hoc and sensor networks (May 30 - 31, 2006). Retrieved on 2007 March 26.
  7. ^ a b c Werner Mohr (2002). Mobile Communications Beyond 3G in the Global Context. Siemens mobile. Retrieved on 2007 March 26.
  8. ^ Noah Schmitz (March 2005). The Path To 4G Will Take Many Turns. Wireless Systems Design. Retrieved on 2007 March 26.
  9. ^ DoCoMo Achieves 5Gbps Data Speed. Wireless Watch Japan (9 February 2007).
  10. ^ Privatkunden Tarife (de). Deutsche Breitband Dienste. Retrieved on 2007 March 26.
  11. ^ WiMAX Day (March 8th, 2007). WiMAX rallies market as Clearwire IPO nets $600 million. WiMAX Spectrum Owners Alliance (WiSOA).
  12. ^ WiMAX Has Company. Wireless Week (1 February 2006). Retrieved on 2007 March 26.

See also

External links

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Source : Wikipedia

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