Adeyinka A. Adewale

Improving Prioritized Handover Performance for Mobile WiMAX by Dynamic Guard Channel Allocation and RSS Quality Factor

In cellular communication, guard channel has been used to provide priority to ongoing call traffic crossing cell boundaries in handover process but the major concern is that most guard channel allocation scheme are fixed channels. System congestion problems arising from traffic pattern in the real world is another major concern relating to fixed allocation of guard channels let alone the huge traffic that will emanate from user mobility in the envisaged converged traffic of 4G networks. Hence, dynamic guard channel (DGC) allocation based on traffic intensity or channel utilization of each traffic type was used in this research and it reduced the new call blocking probability better than the fixed prioritized guard channel (PGC) and non-prioritized channel allocation scheme. Its performance in terms of call dropping probability reduction is comparable with the PGC and slightly better off at poor signal condition. It was revealed that DGC averaged QoS better than the existing channel assignment schemes. An investigation into the RSS quality factor (QF) proposed also, showed that at high quality RSS the blocking and dropping probability of the traffic were reduced for the Mobile WiMAX wireless technology network with mobile assisted handover.

Effect of Increasing Buffer Size on Prioritized Guard Channels with Queue during Call Traffic Congestion

Prioritized guard channel (PGC) assignment with queue was designed to reduce call dropping probability associated with a base station congested with handover call traffic. The Markov chain was used in the analysis of the PGC scheme and queuing discipline was FIFO for a PGC+MAHO scheme. Simulation was carried out using MATLAB. The results showed that increasing buffer size reduces call dropping probability which becomes discontinuous at some value of traffic arrival rate for each buffer size. It was found out that some queuing parameters such as queue product form becomes undefined at an arrival rate for a large buffer size. This limits the extent to which buffer size can be increased. System computational speed was also a contributory factor.

Performance Evaluation of Dynamic Guard Channels Assignment with Queue and Prioritized Schemes

It has been said that dynamic guard channel (DGC) assignment scheme based on traffic intensities averages QoS and performs better than the prioritized guard channel assignment scheme with queue (QPGC) during traffic congestion. This work has extended the investigation to DGC with queue (QDGC) and carried out its comparison with other call traffic channel assignment schemes. Mathematical analysis of the models was done using Markov chain and simulation was carried out in MATLAB. When traffic arrival rates were symmetric, the QPGC had the lower call blocking probability than the QDGC but became the same when the system was congested. However, the performance of the two queuing schemes was the same when handover call traffic was more than new calls traffic.