Performance Modelling and Analysis of Connection Admission Control in OFDMA based WiMAX System with MMPP Queuing

This paper presents a problem of queuing theoretic performance modeling and analysis of Orthogonal Frequency Division Multiple Access (OFDMA) under broad-band wireless networks. We consider a single-cell WiMAX environment in which the base station allocates sub channels to the subscriber stations in its coverage area. The sub channels allocated to a subscriber station are shared by multiple connections at that subscriber station. To ensure the Quality of Service (QoS) performances, two Connection Admission Control (CAC) schemes, namely, threshold-based and queue-aware CAC schemes are considered at a subscriber station. A queuing analytical framework for these admission control schemes is presented considering OFDMA-based transmission at the physical layer. Then, based on the queuing model, both the connection-level and the packetlevel performances are studied and compared with their analogues in the case without CAC. The connection arrival is modeled by a Poisson process and the packet arrival for a connection by a Markov Modulated Poisson Process (MMPP). We determine analytically and numerically different performance parameters, such as connection blocking probability, average number of ongoing connections, average queue length, packet dropping probability, queue throughput and average packet delay.