A Phase-Type Based Markov Chain Model for IEEE 802.16e Sleep Mode and Its Performance Analysis

To support battery powered mobile broadband wireless access devices efficiently, IEEE 802.16e defines a sleep mode operation for conserving the power of mobile terminals. In this paper we propose a theoretical Phase-type (PH) based Markov chain model to analyze the performance of IEEE 802.16e sleep mode operation. The model describes the behavior of the mobile stations working in sleep mode. In particular, the service process is designed as a discrete PH model. By means of the mathematic tools of PH theory we then derive the closed-form expressions of the mean sojourn time of packets and power consumption. Comparison with simulation results shows that the model provides an accurate prediction of the system performance. Furthermore, we propose a simple utility function to quantify the efficiency of sleep mode operation which takes the joint effect of sojourn time and power saving into account. This function allows mobile stations to decide when to enable sleep mode operation for power saving.