Queueing analysis for OFDM subcarrier allocation in broadband wireless multiservice networks

In this paper, we perform a tele-traffic queueing analysis for OFDM subcarrier allocation in wireless multiservice networks. For this purpose two call admission control algorithms, the batch blocking scheme and the partial blocking scheme, are proposed. Call connection requests are classified into two different types, narrow-band and wide-band. For either class of calls, the traffic process is characterized as batch arrival, as each call may request multiple subcarriers to satisfy its Quality-of-Service (QoS) requirements. The batch size is a random variable which obeys a probability mass function (pmf) with a realistic maximum value. In addition, the service times for various call classes are different. Consequently, an OFDM-based broadband wireless multiservice network can be formulated as a multiclass multiserver batch arrival queueing system. The methodology and results are further generalized into a multiple-class scenario with service priority provision. Formulae are developed for evaluation of the following performance metrics: the probability that a call will be blocked, the average number of subcarriers used, and bandwidth utilization. Numerical results are presented to demonstrate the interactions between key parameters and performance metrics. The analytical model was validated by the simulation results, showing the fact that it can be used as an efficient tool for design of future-generation broadband wireless access networks.