Energy efficiency has become one of the most important issues in wireless body area network(WBAN).In this paper,an energy-efficient medium access control(MAC)protocol for WBAN is proposed based on human body posture under walking scenery.Due to person’s movements,WBAN is a dynamic network,which means that traditional static protocols are no more suitable for it.For solving this problem,firstly,the feature of human walking at a constant speed is analyzed and we divide a spell of movements into a sequence of key frames just like a video constituted by numbers of continuous frames.As a result,the dynamic walking process is translated into several static postures,which the static MAC protocol could be used for.Secondly,concerning the performance of network lifetime,we design a posture-aware approach for lifetime maximization(PA-DPLM).With analytical and simulation results provided,we demonstrate that PA-DPLM protocol is energy-efficient and can be used under constant speed walking scenery. Energy efficiency has become one of the most important issues in wireless body area network (WBAN) .In this paper, an energy-efficient medium access control (MAC) protocol for WBAN is proposed based on human body posture under walking scenery. movements, WBAN is a dynamic network, which means that traditional static protocols are no more suitable for it.For solving this problem, first, the feature of human walking at a constant speed is analyzed and we divide a spell of movements into a sequence of key frames just like a video composed by numbers of continuous frames. As a result, the dynamic walking process is translated into several static postures, which the static MAC protocol could be used for. Secondarily, concerning the performance of network lifetime, we design a posture-aware approach for lifetime maximization (PA-DPLM) .With analytical and simulation results provided, we demonstrate that PA-DPLM protocol is energy-efficient and can be used under constant speed walking scenery.