An Efficient Cross-Layer Reliable Retransmission Scheme for the Human Body Shadowing in IEEE 802.15.6-Based Wireless Body Area Networks

In recent years, a number of middle-aged and elderly people with chronic diseases are increasing. In addition, patients with chronic diseases do not cause health harm in a short period and need long-term hospitalization. Thus, wireless body area network is the best scheme for daily care. According to the human physiological information, it not only sends real-time notifications to users but also reduces delays of the notification regarding patients' conditions. The physician early identifies the cause of disease and applies remedies according to indications. Daily activities of a person affect the transmission signal of sensor nodes such as walk or run. Thus, the sensor nodes, which have to retransmit the failed frames, are continuously interfered a period time by human body shadowing, so the retransmission procedure should be deferred. If the sensor nodes immediately retransmit the failed frames, they may suffer from the human posture interference again. Therefore, we propose an efficient cross-layer reliable retransmission scheme (CL-RRS) in IEEE 802.15.6 without additional control overheads. The proposed scheme not only detects the information of the sensor nodes with failed transmission frames to allocate retransmission resources, but also increases the successful probability of frame retransmission. Simulation results validated by our mathematical analysis show that the CL-RRS significantly improves frame loss rate and average transmission time, as well as reduces power consumption.