In recent years, interests in the application of wireless body network (WBN) have grown considerably. Wireless body sensor nodes assume deploying a stationary sensor network over a human body area. Among the well-known specifications, IEEE 802.15.4 originally designed for low-power, low-rate, and short-distance wireless personal area networks (WPANs) has become one of the promising candidates for interconnections between wireless sensor nodes. IEEE 802.15.4 uses a modified carrier-sense multiple access with collision avoidance (CSMA/CA) MAC protocol to access channel for transmission data; however, it suffers from inefficient channel utilization because the physical carrier sensing is only performed after the backoff period. In this paper, a rotational listening strategy (RLS) is proposed to increase the rate of successful transmission for WBN. The channel access period is logically partitioned into a number of mini-slots that are individually allocated to nodes. In this case, inefficient channel utilization and collisions can be resolved simultaneously, meanwhile retaining fairness criterion. In addition, an enhanced RLS is proposed to handle the load unbalance situation among nodes. This paper also provides a co-existence solution for the situation where there are nodes without RLS associating with an RLS-enabled WSN. Analytical and numerical simulations are both studied to evaluate the performance of RLS. Both results illustrate that RLS indeed improves transmission efficiency as well as energy consumption.
