The success in 2G mobile system prompted the development of 3G (third generation) mobile systems. The next evolution in wireless communication is 4G (fourth generation) systems.
The reasons to have 4G are as follows:
It supports interactive multimedia services such as wireless internet, teleconferencing etc.Challenges to be faced while migrating to 4G
Higher bit rates.
Service portability and global mobility.
Scalable mobile networks.
Certain challenges have to be faced. Now let us have a look at these:
1.Multimode user terminal: Multimode user terminal is a device operating in different modes supporting a large type of 4G services and wireless networks by reconfiguring themselves to adapt to different wireless networks. They encounter several design problems like limitations in the device cost, size, backward compatibility to systems and power consumption.
2.Wireless network discovery: Availing 4G services need the multimode user terminal to find and select the required wireless network. Discovery of 4G systems will be much more challenging than 3G due to the heterogeneity of the networks and their access protocols.
3.Wireless network selection: 4G will offer the users a option to select a wireless network providing optimized performance and high QoS for a specific place, time and desired service (communication, multimedia). But the parameters that define high QoS and optimized performance at specific instant must be clearly defined to form the network selection procedure efficient and transparent to the end user.
4.Terminal mobility: Terminal mobility is an important characteristic to satisfy the “Anytime Anywhere” promise of 4G. It permits the mobile users to move across the geographic boundaries of wireless networks. Two important problems in terminal mobility are location and hand off management. Location management includes tracking the location of the mobile users and maintaining data like the authentication information, QoS capabilities, and the original and the current cell location. Handoff management is maintaining the continuing communication when the terminal roams.
5.Network infrastructure and QoS support: Unlike previous generation networks such as 2G and 3G, 4G is an integration of IP and non-IP based system. Before 4G, QoS designs were made with a specific wireless system in mind. But in 4G systems QoS designs should consider the integration of various wireless networks to ensure QoS for the end-to-end services.
6.Security: Most of the security schemes and the encryption/decryption protocols of the present generation networks were designed only for specific services. They appear to be very inflexible to be used across the heterogeneous architecture of 4G that desires dynamically adaptive, reconfigurable and light-weight security mechanism.
7.Fault tolerance: Wireless networks resemble a tree-like topology. Any failure in one of the levels will affect all the network elements at the levels below. This problem may become more complex because of the multiple tree topologies. Adequate research work is needed to devise a method for fault tolerance in wireless networks.