Analytical Performance Evaluation of IEEE 802.15.4 with Multiple Transmission Queues for Providing QoS under Non-Saturated Conditions

This paper investigates the effects of adopting multiple transmission queues in IEEE 802.15.4 to differentiate frame sending priorities for providing QoS (Quality of Service) services. By employing different contention window operational parameters for various traffic classes like IEEE 802.11e, the multi- queue system can send frames of higher priority class more rapidly than those of the lower ones. For the performance evaluation of multi- queue's behavior under both saturated and unsaturated traffic conditions, this paper proposes an analytical model which integrates models for conventional 802.15.4 and legacy 802.11e. To enhance the accuracy, furthermore, the model accommodates the deferment behaviors and transmission retries that have not been accounted in traditional 802.15.4 models. Our analytical model predicts that the multi- queue scheme separates the throughput of two different classes by up to 46% without wasting the bandwidth when the two classes contend over the wireless channel. Simulation results validate our model's accuracy within 7% discrepancy at maximum.