We analyze IEEE 802.16e medium access control (MAC) sublayer and provides a simple analytical model to compute the 802.16e MAC throughput. Our approach is to begin with a key approximation made by [1] in IEEE 802.11. This study leads to a fixed point equation, which characterizes the operating point of system. It allows us to compute the attempt rate of a mobile in saturated case as well as the throughput formulas for the overall network. Moreover, our performance model deals with a recently released IEEE802.16 criterium : the tr parameter, which have a main impact on the MAC performance.