In the 1G and 2G of wireless cellular systems, CAC has been developed for a single service environment. In the 3G and beyond wireless cellular systems, multimedia services such as video, data, and audio are to be offered with various QoS profiles. Hence, more sophisticated CAC schemes are needed to develop for dealing with these challenges. CAC is needed for admitting reasonable number of users in the sense that CAC can satisfy various QoS constraints for different services and also maximize the spectrum utilization for systems. CAC schemes play a very important role
in the performance of 3G wireless cellular network systems as it directly
controls the number of users in a cell and thus limit the interference in the system.CAC has been extensively studied in wireless cellular networks as an essential tool for congestion control and QoS provisioning. CAC in wireless cellular networks has been receiving a great deal of attention during the last two decades due to the growing popularity of wireless cellular network and the central role that CAC plays in QoS provisioning.
Quality of service (QoS) plays a major role in wireless cellular networks and it is one of the most important issues from both the users and operators point of view. All the parameters related to QoS are not same important for all users and requested applications. The satisfaction level of different users also does not depend on same QoS parameters. Our proposed CAC scheme gives preferential treatment to higher priority calls, such as hand-off calls of all class of service (data, voice and video), by reserving some bandwidth to reduce handoff failures. In addition, queuing is also used to enhance the hand-off success probability. The scheme uses the effective load as an admission criterion and applies different thresholds for new and hand-off calls. Finally, we consider three types of services: video, voice and data calls. We assure that our scheme reduces the drop hand-off calls by
queuing mechanism and increases the system capacity; hence the Grade-of-Service (GoS) and the system performance can significantly improve.