With the rapid development of communication networks, it is expected that fourth generation mobile systems will be launched within decades. Fourth generation (4G) mobile systems focus on seamlessly integrating the existing wireless technologies including GSM, wireless LAN, and Bluetooth. This contrasts with third generation (3G), which merely focuses on developing new standards and hardware. 4G systems will support comprehensive and personalized services providing stable system performance and quality service. This paper gives the details about the need for mobile communication and its development in various generations. In addition, the details about the working of 4G mobile communication were given. Finally, it narrates how 4G mobile communication will bring a new level of connectivity and convenece in communication.
Communication is one of the important areas of electronics and always been a focus for exchange of information among parties at locations physically apart. There may be different mode of communication. The communication may be wired or wireless between two links. Initially the mobile communication was limited to between one pair of users on single channel pair. Mobile communication has undergone many generations. The first generation of the RF cellular used analog technology. The modulation was FM and the air interface was FDMA. Second generation was an offshoot of Personal Land Mobile Telephone System (PLMTS). It used Gaussian Shift Keying modulation (GMSK). All these systems had practically no technology in common and frequency bands, air interface protocol, data rates, number of channels and modulation techniques all were difficult. Dynamic Quality of Service (QoS) parameter was always on the top priority list. Higher transmission bandwidth and higher efficiency usage had to be targeted. On this background development of 3G mobile communication systems took place. In this Time Division Duplex (TDD) mode technology using 5MHz channels was used. This had no backward compatibility with any of the predecessors. But 3G appeared to be somewhat unstable technology due to lack of standardization, licensing procedures and terminal and service compatibility. Biggest single inhibitor of any new technology in mobile communication is the mobile terminal availability in the required quantity, with highest QoS and better battery life. The future of mobile communication is FAMOUS-FUTUERE Advanced Mobile Universal Systems, Wide-band TDMA, Wideband CDMA are some of the technologies. The data rates targeted are 20MBPS. That will be the 4G in the mobile communication. 4G must be hastened, as some of the video applications cannot be contained within 3G.
2.DEVELOPMENT OF THE MOBILE COMMUNICATION
The communication industry is undergoing cost saving programs reflected by slowdown in the upgrade or overhaul of the infrastructure, while looking for new ways to provide third generation (3G) like services and features with the existing infrastructures. This has delayed the large-scale development of 3G networks, and given rise to talk of 4G technologies. Second generation (2G) mobile systems were very successful in the previous decade. Their success prompted the development of third generation (3G) mobile systems. While 2G systems such as GSM, andIS-95 etc. were designed to carry speech and low bit-rate data. 3G systems were designed to provide higher data-rate services. During the evolution from 2G to3G, a range of wireless systems, including GPRS, IMT-2000, Bluetooth, WLAN, and Hiper LAN have been developed. All these systems were designed independently, targeting different service types, data rates, and users. As these systems all have their own merits and shortcomings, there is no single system that is good to replace all the other technologies. Instead of putting into developing new radio interface and technologies for 4G systems, it is believed in establishing 4G systems is a more feasible option.
3. ARCHITECTURAL CHANGES IN 4G TECHNOLOGY
In 4G architecture, focus is on the aspect that multiple networks are able to function in such a way that interfaces are transparent to users and services. Multiplicities of access and service options are going to be other key parts of the paradigm shift. In the present scenario and with the growing popularity of Internet, a shift is needed to switch over from circuit switched mode to packet switched mode of transmission. However 3G networks and few others, packet switching is employed for delay insensitive data transmission services. Assigning packets to virtual channels and then multiple physical channels would be possible when access options are expanded permitting better statistical multiplexing. One would be looking for universal access and ultra connectivity, which could be enabled by:
(a) Wireless networks and with wire line networks.
(b) Emergence of a true IP over the air technology.
© Highly efficient use of wireless spectrum and resources.
(d) Flexible and adaptive systems and networks.
4. SOME KEY FEATURES OF 4G TECHNOLOGY
Some key features (mainly from the users point of view) of 4G networks are:
1. High usability: anytime, anywhere, and with any technology
2. Support for multimedia services at low transmission cost
4. Integrated services
First, 4G networks are all IP based heterogeneous networks that allow users to use any system at any time and anywhere. Users carrying an integrated terminal can use a wide range of applications provided by multiple wireless networks.
Second, 4G systems provide not only telecommunications services, but also data and multimedia services. To support multimedia services high data-rate services with good system reliability will be provided. At the same time, a low per-bit transmission cost will be maintained.
Third, personalized service will be provided by the new generation network.
Finally, 4G systems also provide facilities for integrated services. Users can use multiple services from any service provider at the same time.
To migrate current systems to 4G with the features mentioned above, we have to face number challenges. Some of them were discussed below.
4.1 MULTIMODE USER TERMINALS
In order to use large variety of services and wireless networks in 4G systems, multimode user terminals are essential as they can adopt different wireless networks by reconfiguring themselves. This eliminates the need to use multiple terminals (or multiple hardware components in a terminal). The most promising way of implementing multimode user terminals is to adopt the software radio approach. The analog part of the receiver consists of an antenna, a band pass filter (BPF), and a low noise amplifier (LNA). The received analog signal is digitized by the analog to digital converter (ADC) immediately after the analog processing. The processing in the next stage (usually still analog processing in the conventional terminals) is then performed by a reprogrammable base band digital signal processor (DSP). The Digital Signal Processor will process the digitized signal in accordance with the wireless environment.
4.2. TERMINAL MOBILITY
In order to provide wireless services at any time and anywhere, terminal mobility is a must in 4G infrastructures, terminal mobility allows mobile client to roam across boundaries of wireless networks. There are two main issues in terminal mobility: location management and handoff management. With the location management, the system tracks and locates a mobile terminal for possible connection. Location management involves handling all the information about the roaming terminals, such as original and current located cells, authentication information, and Quality of Service (QoS) capabilities. On the other hand, handoff management maintains ongoing communications when the terminal roams. MobileIPv6 (MIPv6) is a standardized IP-based mobility protocol for Ipv6 wireless systems. In this design, each terminal has an IPv6 home address whenever the terminal moves outside the local network, the home address becomes invalid, and the terminal obtain a new Ipv6 address (called a care-of address) in the visited network. A binding between the terminal’s home address and care-of address is updated to its home agent in-order to support continuous communication.