An Analytical Model for IEEE 802.15.4 with Sleep Mode Based on Time-Varying Queue

A novel queuing model in this paper is proposed to provide a tool for performance evaluation to IEEE 802.15.4 Medium Access Control (MAC) protocol with sleep mode enabled. IEEE 802.15.4 node with sleep mode enabled behaves in a different way from other queuing models because the node goes to sleep periodically and thus packets arriving in sleep period accumulate in the beginning of the active portion, which makes a heavier load at the beginning than any other time. This model analyzes this behavior by using an embedded discrete-time Markov chain model that includes the slot number in the states to obtain the time-varying queue length. To obtain the service time, we introduce the virtual service time into this model which makes the proposed queuing model different from models in any previously published works. The accuracy of the proposed model is validated by Monte Carlo simulations. The proposed model can accurately evaluate the performance of IEEE 802.15.4.