4G MOBILE COMMUNICATION SYSTEMS

The success of Second-generation (2G) mobile systems in the previous decade prompted the development of third-generation (3G) mobile systems. While 2G systems such as GSM, IS-95, and cdmaOne 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 to 3G, a range of wireless systems, including General Packet Radio Services (GPRS). International Mobile Telecommunications-2000 (IMT-2000). Bluetooth, WLAN, and HiperLAN, have been developed. All these systems were designed independently, targeting different service types, data rates, and users. As these systems have their own merits and demerits, there is no single system that is good enough to replace all the other technologies. Researchers are making efforts to establish 4G systems that integrate existing and newly developed wireless systems as a more feasible option. Different research programs, such as Mobile Virtual Centre of Excellence (VCE), MIRAI, and DoCoMo, have their own visions for 4G features and implementations.

At present, plethora of wireless technologies with their own merits and demerits exist globally; the upcoming 4G mobile communications system is foreseeing potentially a smooth merger of these technologies with a goal to support cost effective seamless communication at high data rate supported with global roaming and user customized personal services.

As discussed 4G will be an IP based wireless network replacing the old Signaling System 7 (SS7) telecommunications protocol, which is considered massively redundant as shown in figure 1 This is because SS7 signal transmission consumes a larger part of network bandwidth even when there is no signalling traffic for the simple reason that it uses a call setup mechanism to reserve bandwidth, rather time/frequency slots in the radio waves. IP networks, on the other hand, are connectionless and use the slots only when they have data to send. Hence there is optimum usage of the available bandwidth.

Figure 1: Example of IP based networks

 

The goal of 4G will be to replace the entire core of cellular networks with a single worldwide cellular network completely standardized based on the (Internet Protocol) IP for video, packet data utilizing Voice over IP (VoIP) and multimedia services. The newly standardized networks would provide uniform video, voice, and data services to the cellular handset or handheld Internet appliance, based entirely on IP (Internet Protocol).