An adaptive multi-class call admission control for multimedia wireless networks

In this dissertation, we classify handoff traffic into two priority classes, realtime and non-realtime. To provide the different priority classes with the quality of service required, we extended the basic guard-channel scheme to include multi-level guard-channel reservation for the different priority classes. An adaptive version of this multi-guard channel scheme, which adapts the number of the guard channels for each priority class to the changing network congestion, is introduced to better utilize the network resources. When congestion is heavy, more channels are reserved for the high priority classes, but when congestion is light, more channels are made available to the lower priority classes. Simulation results show that this adaptive scheme performs as well as the deterministic optimal solution of this system, which is the performance of the different classes when the guard-channel sizes are optimized for best low priority class performance.;To support data communications, which can require multiple channels per call, the adaptive scheme was extended to use a best effort technique. Best effort is a technique where calls requiring multiple channels are allocated a smaller number of channels than requested based upon availability of channels. Since data communication is delay tolerant, the multi-channel data handoff calls were considered a non-realtime handoff class, with priority lower than that of the realtime handoff calls. When compared with an adaptive scheme with a number of channels reserved exclusively for the multi-channel class, the adaptive scheme with best effort extension provided a better performance for all the priority classes at a cost of a longer channel holding time. When employing a user-based priority classification instead of call-based classification, the call admission-control problem transforms into a multiple priority-class problem with multi-rate calls. Multi-rate calls are calls that require a variable number of channels. The adaptive scheme is compared to three best effort extensions, best effort for all classes, best effort for the highest two classes, and best effort for the highest priority class only. Although there is a performance gain from using the best effort extension, this gain is not substantial.