ABSTRACT:-
The approaching 4G (fourth generation) mobile communication systems are projected to solve still-remaining problems of 3G (third generation) systems and to provide a wide variety of new services, from high-quality voice to high-definition video to high-data-rate wireless channels. The term 4G is used broadly to include several types of broadband wireless access communication systems, not only cellular telephone systems. One of the terms used to describe 4G is MAGIC—Mobile multimedia, Anytime anywhere, Global mobility support, Integrated wireless solution, and Customized personal service. As a promise for the future, 4G systems, that is, cellular broadband wireless access systems have been attracting much interest in the mobile communication arena. The 4G systems not only will support the next generation of mobile service, but also will support the fixed wireless networks. This paper presents an overall vision of the 4G features, framework, and integration of mobile communication. The features of 4G systems might be summarized with one word—integration. The 4G systems are about seamlessly integrating terminals, networks, and applications to satisfy increasing user demands. The continuous expansion of mobile communication and wireless networks shows evidence of exceptional growth in the areas of mobile subscriber, wireless network access, mobile services, and applications.
INTRODUCTION:-
Pick up any newspaper today and it is a safe bet that you will find an article somewhere relating to mobile communications. If it is not in the technology section it will almost certainly be in the business section and relate to the increasing share prices of operators or equipment manufacturers, or acquisitions and take-overs thereof. Such is the pervasiveness of mobile communications that it is affecting virtually everyone’s life and has become a major political topic and a significant contributor to national gross domestic product (GDP).
Wireless mobile-communications systems are uniquely identified by "generation" designations. Introduced in the early 1980s, first-generation (1G) systems were marked by analog-frequency modulation and used primarily for voice communications. Second - generation (2G) wireless-communications systems, which made their appearance in the late 1980s, were also used mainly for voice transmission and reception The wireless system in widespread use today goes by the name of 2.5G—an "in-between" service that serves as a stepping stone to 3G. Whereby 2G communications is generally associated with Global System for Mobile (GSM) service, 2.5G is usually identified as being "fueled" by General Packet Radio Services (GPRS) along with GSM.
In 3G systems, making their appearance in late 2002 and in 2003, are designed for voice and paging services, as well as interactive-media use such as teleconferencing, Internet access, and other services. The problem with 3G wireless systems is bandwidth—these systems provide only WAN coverage ranging from 144 kbps (for vehicle mobility applications) to 2 Mbps (for indoor static applications). Segue to 4G, the "next dimension" of wireless communication. The 4g wireless uses Orthogonal Frequency Division Multiplexing (OFDM), Ultra Wide Radio Band (UWB), and Millimeter wireless and smart antenna. Data rate of 20mbps is employed. Mobile speed will be up to 200km/hr.Frequency band is 2-8 GHz. it gives the ability for world wide roaming to access cell anywhere.
In 3G systems, making their appearance in late 2002 and in 2003, are designed for voice and paging services, as well as interactive-media use such as teleconferencing, Internet access, and other services. The problem with 3G wireless systems is bandwidth—these systems provide only WAN coverage ranging from 144 kbps (for vehicle mobility applications) to 2 Mbps (for indoor static applications). Segue to 4G, the "next dimension" of wireless communication. The 4g wireless uses Orthogonal Frequency Division Multiplexing (OFDM), Ultra Wide Radio Band (UWB), and Millimeter wireless and smart antenna. Data rate of 20mbps is employed. Mobile speed will be up to 200km/hr.Frequency band is 2-8 GHz. it gives the ability for world wide roaming to access cell anywhere.
DEFINITION:-
4G is the short term for fourth-generation wireless, the stage of broadband mobile communications that will supersede the third generation (3G). it is expected that end-to-end IP and high-quality streaming video will be among 4G's distinguishing features. Fourth generation networks are likely to use a combination of WiMAX and WiFi. 4G technologies are sometimes referred to by the acronym "MAGIC," which stands for Mobile multimedia, Anytime/any-where, Global mobility support, Integrated wireless and Customized personal service.
Although 3G networks were really about the technology, 4G networks are both a technology and a business transformation. 4G will potentially reshape not just the wireless industry, but also cable, wireline and handset companies. It will also simultaneously provide the media and entertainment industries another avenue for content delivery.
FEATURES:
• Support for interactive multimedia, voice, streaming video, Internet, and other broadband services
• IP based mobile system
• High speed, high capacity, and low cost per bit
• Seamless switching, and a variety of Quality of Service driven services
• Ad hoc and multi hop networks (the strict delay requirements of voice make multi hop network service a difficult problem)
• Better spectral efficiency
• Avoidance or prevention of congestion
• Seamless network of multiple protocols and air interfaces (since 4G will be all IP, look for 4G systems to be compatible with all common network technologies, including802.11, WCDMA, Blue tooth, and Hyper LAN)
• An infrastructure to handle pre existing 3G systems, along with other wireless technologies.
4G HISTORY:
At the end of the 1940’s, the first radio telephone service was introduced, and was designed to users in cars to the public land-line based telephone network. Then, in the 60s, a system launched by Bell Systems, called IMTS, or, “Improved Mobile Telephone Service", brought quite a few improvements such as direct dialling and more bandwidth. The very first analog systems were based upon IMTS and were created in the late 60s and early 70s. The systems were called "cellular" because large coverage areas were split into smaller areas or "cells", each cell is served by a low power transmitter and receiver.
THE 1G OR FIRST GENERATION:
1G analog system for mobile communications saw two key improvements during the 1970s: the invention of the microprocessor and the digitization of the control link between the mobile phone and the cell site.
Advance mobile phone system (AMPS) was first launched by the US
2G OR SECOND GENERATION:
2G first appeared around the end of the 1980’s, the 2G system digitized the voice signal, as well as the control link. This new digital system gave a lot better quality and much more capacity (i.e. more people could use their phones at the same time), all at a lower cost to the end consumer. Based on TDMA, the first commercial network for use by the public was the Global system for mobile communication (GSM).
3G or THIRD GENERATION:-
3G systems promise faster communications services, entailing voice, fax and Internet data transfer capabilities, the aim of 3G is to provide these services any time, anywhere throughout the globe, with seamless roaming between standards. ITU’s IMT-2000 is a global standard for 3G and has opened new doors to enabling innovative services and application for instance, multimedia entertainment, and location-based services, as well as a whole lot more. In
2001, 3G technology supports around 144 Kbps, with high speed movement, i.e. in a vehicle. 384 Kbps locally, and up to 2Mbps for fixed stations, i.e. in a building.
4G or FOURTH GENERATION:-
For 1 and 2G standards, bandwidth maximum is 9.6 kbit/sec, This is approximately 6 times slower than an ISDN (Integrated services digital network). Rates did increase by a factor of 3 with newer handsets to 28.8kbps. This is rarely the speed though, as in crowded areas, when the network is busy, rates do drop dramatically.
Third generation mobile, data rates are 384 kbps (download) maximum, typically around 200kbps, and 64kbps upload. These are comparable to home broadband connections.
Fourth generation mobile communications will have higher data transmission rates than 3G. 4G mobile data transmission rates are planned to be up to 100 megabits per second on the move and 1000gigbits per second stationary, this is a phenomenal amount of bandwidth, only comparable to the bandwidth workstations get connected directly to a LAN.
4G KEY TECHNOLOGIES:
Access schemes:
As the wireless standards evolved, the access techniques used also exhibited increase in efficiency, capacity and scalability. The first generation wireless standards used plain TDMA and FDMA. In the wireless channels, TDMA proved to be less efficient in handling the high data rate channels as it requires large guard periods to alleviate the multipath impact. Similarly, FDMA consumed more bandwidth for guard to avoid inter carrier interference. So in second generation systems, one set of standard used the combination of FDMA and TDMA and the other set introduced an access scheme called CDMA. Usage of CDMA increased the system capacity, but as a drawback
placed a soft limit on it rather than the hard limit (i.e. a CDMA network will not reject new clients when it approaches its limits, resulting in a denial of service to all clients when the network overloads). Data rate is also increased as this access scheme (providing the network is not reaching its capacity) is efficient enough to handle the multipath channel. This enabled the third generation systems, such as IS-2000, UMTS, HSXPA, 1xEV-DO, TD-CDMA and TD-SCDMA, to use CDMA as the access scheme. However, the issue with CDMA is that it suffers from poor spectral flexibility and computationally intensive time-domain equalization (high number of multiplications per second) for wideband channels.
OFDM, a form of multi-carrier modulation, works by dividing the data stream for transmission at a bandwidth B into N multiple and parallel bit streams, spaced B/N apart. Each of the parallel bit streams has a much lower bit rate than the original bit stream, but their summation can provide very high data rates. N orthogonal sub-carriers modulate the parallel bit streams, which are then summed prior to transmission.
An OFDM transmitter accepts data from an IP network, converting and encoding the data prior to modulation. An IFFT (inverse fast Fourier transform) transforms the OFDM signal into an IF analog signal, which is sent to the RF transceiver. The receiver circuit reconstructs the data by reversing this process. With orthogonal sub-carriers, the receiver can separate and process each sub-carrier without interference from other sub-carriers. More impervious to fading and multi-path delays than other wireless transmission techniques, ODFM provides better link and communication quality.
Recently, new access schemes like Orthogonal FDMA (OFDMA), Single Carrier FDMA (SC-FDMA), Interleaved FDMA and Multi-carrier CDMA (MC-CDMA) are gaining more importance for the next generation systems. These are based on efficient FFT algorithm and frequency domain equalization, resulting lower number of multiplications per second. They also make it possible to control the bandwidth and form the spectrum in a flexible way. However, they require advanced dynamic channel allocation and traffic adaptive scheduling.
Ultra Wide Band
A UWB transmitter spreads its signal over a wide portion of the RF spectrum, generally 1 GHz wide or more, above 3.1GHz. The FCC has chosen UWB frequencies to minimize interference to other commonly used equipment, such as televisions and radios. This frequency range also puts UWB equipment above the 2.4 GHz range of microwave ovens and modern cordless phones, but below 802.11a wireless Ethernet, which operates at 5 GHz.
UWB equipment transmits very narrow RF pulses—low power and short pulse period means the signal, although of wide bandwidth, falls below the threshold detection of most RF receivers. Traditional RF equipment uses an RF carrier to transmit a modulated signal in the frequency domain, moving the signal from a base band to the carrier frequency the transmitter uses. UWB is "carrier-free", since the technology works by modulating a pulse, on the order of tens of microwatts, resulting in a waveform occupying a very wide frequency domain. The wide bandwidth of a UWB signal is a two-edged sword. The signal is relatively secure against interference and has the potential for very high-rate wireless broadband access and speed. On the other hand, the signal also has the potential to interfere with other wireless transmissions. In addition, the low-power constraints placed on UWB by the FCC, due to its potential interference with other RF signals, significantly limits the range of UWB equipment (but still makes it a viable LAN technology).
One distinct advantage of UWB is its immunity to multi-path distortion and interference. Multi-path propagation occurs when a transmitted signal takes different paths when propagating from source to destination. The various paths are caused by the signal bouncing off objects between the transmitter and receiver.
One distinct advantage of UWB is its immunity to multi-path distortion and interference. Multi-path propagation occurs when a transmitted signal takes different paths when propagating from source to destination. The various paths are caused by the signal bouncing off objects between the transmitter and receiver.
IPv6 support:
Unlike 3G, which is based on two parallel infrastructures consisting of circuit switched and packet switched network nodes respectively, 4G will be based on packet switching only. This will require low-latency data transmission.
IPv6 is short for "Internet Protocol Version 6". IPv6 is the "next generation" protocol designed by the IETF to replace the current version Internet Protocol, IP Version 4 ("IPv4").
By the time that 4G is deployed, the process of IPv4 address exhaustion is expected to be in its final stages. Therefore, in the context of 4G, IPv6 support is essential in order to support a large number of wireless-enabled devices. By increasing the number of IP addresses, IPv6 removes the need for Network Address Translation (NAT), a method of sharing a limited number of addresses among a larger group of devices, although NAT will still be required to communicate with devices that are on existing IPv4 networks.
Advanced Antenna Systems:
The performance of radio communications depends on an antenna system, refer to smart or intelligent antenna. Recently, multiple antenna technologies are emerging to achieve the goal of 4G systems such as high rate, high reliability, and long range communications. 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 then 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 MIMO(as a branch of intelligent antenna). Spatial multiplexing techniques makes the receivers very complex, and therefore it is typically combined with Orthogonal frequency-division multiplexing (OFDM) or with Orthogonal Frequency Division Multiple Access (OFDMA) modulation, where the problems created by multi-path channel are handled efficiently.Software-Defined Radio (SDR):
A software-defined radio system, or SDR, is a radio communication system where components that have typically been implemented in hardware are instead implemented using software on a personal computer or embedded computing devices.SDR is one form of open wireless architecture (OWA). Since 4G is a collection of wireless standards, the final form of a 4G device will constitute various standards. This can be efficiently realized using SDR technology, which is categorized to the area of the radio convergence.
Software Defined Radio (SDR) benefits from today’s high processing power to develop multi-band, multi-standard base stations and terminals. Although in future the terminals will adapt the air interface to the available radio access technology, at present this is done by the infrastructure. Several infrastructure gains are expected from SDR. For example, to increase network capacity at a specific time (e.g. during a sports event), an operator will reconfigure its network adding several modems at a given Base Transceiver Station (BTS). SDR makes this reconfiguration easy. In the context of 4G systems, SDR will become an enabler for the aggregation of multi-standard pico/micro cells. For a manufacturer, this can be a powerful aid to providing multi-standard, multi-band equipment with reduced development effort and costs through simultaneous multi-channel processing.
APPLICATIONS:-
Telegeoprocessing:- You will be able to see the internal layout of a building during an emergency rescue. This type of application is some time referred to as ‘telegeoprocessing’.
A remote database will contain the graphical representation of streets, buildings and physical characteristics of a large metropolis. Blocks of this database will be transmitted in rapid sequence to a vehicle, where a rendering program will permit the occupants to visualize the environment ahead. They may also ‘virtually’ see the internal layout of buildings to plan an emergency rescue or engage hostile elements hidden in the building.
Telemedicine:- A paramedic assisting a victim of a traffic accident in a remote location could access medical records (X-rays) and establish a video conference so that a remotely based surgeon could provide ‘on-scene’ assistance.
Crisis management application:-In the event of natural disasters where the entire communications infrastructure is in disarray, restoring communications quickly is essential. With wideband wireless mobile communications, limited and even total communication capability(including Internet and video services) could be set up within hours instead of days or even weeks required at present for restoration of wire line communications.
SWOT ANALYSIS:-
Considering 4G characteristics, we can find out strengths, weaknesses, opportunities and threats of 4G with better understandings. The lists and findings follow.
Strengths in 4G:
Ø 4G visions take into account installed base and past investments
Ø Strong position of telecommunications vendors expected in the marketplace.
Ø Faster data transmission and higher bit rate and bandwidth, allow more business applications and commercialization
Ø Has advantage for personalized multimedia communication tools
Weakness in 4G:
Ø No large user community for advanced mobile data applications yet
Ø Growing divergence between telecommunications vendors and operators
Ø Comparatively higher cost to use and deploy infrastructure compared fast mobile generation
Opportunities in 4G:
Ø Evolutionary approach may yield opportunities for the 4G
Ø Emphasis on heterogeneous networks capitalizes on past investments
Ø Strategic alliance and coalition opportunities with traditional non-telecommunication industries
Ø Sophisticated and mature commercialization of 4G technology would encourage more applications of e-commerce and m-commerce
Ø Worldwide economy recover stimulates consumption and consumer confidence, therefore bring in opportunities for telecommunication sections
Ø It is expected and predicted that consumers will continue to replace handsets with newer technology at a fast rate.
Ø Desirable higher data capacity rates, the growth opportunity for 4G is very bright and hopeful.
Threats in 4G:
Ø Faster rate of growth and developments in other region
Ø Since 3G mobile is still in the market, it squeezes the market competition in the mobile industry.
Ø Seamless roaming and seamless transfer of services.
CONCLUSION:-
The mobile technology though reached only at 3G now, 4G offers us to provide with a very efficient and reliable wireless communication system for seamless roaming over various network including internet which uses IP network. The 4G system will be implemented in the coming years which are a miracle in the field of communication engineering technology. The 4G Vision is a living document which intends to update and amend as time and knowledge progress. It will act as the umbrella vision to a large research program and place in context the detailed research work that will take place in the various areas.
“The development in day-to-day communication after 3G is not just an 4G EVOLUTION, It’s a REVOLUTION.”
REFERENCES:-
1. B. G. Evans and K. Baughan, "Visions of 4G," Electronics and Communication Engineering Journal, Dec. 2002.
2. Glisic, Savo. Advanced Wireless Communications: 4G Technologies.Hoboken, NJ, John Wiley & Sons, 2004
3. And Source: Internet.
v www.3g4g.co.uk/4g
v www.3g4g.blogspot.com
v www.wikipedia.org
v www.4g.co.uk
v www.4gworld.com
v www.ieee.org
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