Delay analysis of ARQ protocol for energy-efficient transmission in WBAN

Due to its highly potential applications in the healthcare and medical fields, Wireless Body Area Network(WBAN) has been attracted from many researches in recent years. In WBANs, an energy efficiency is still a challenging issue. In our previous work [5], we investigated the energy efficiency models of 1-hop and cooperative communications further in multipath fading and proposed the energy efficiency model of 2-hop communication. However, the average end-to-end delay has not been explored. In this paper, we simulate the average end-to-end delay of a S-D pair of the energy-efficient 1-hop, cooperative and 2-hop communications in multipath fading. The Automatic Repeat Request(ARQ) protocol with the utilization of stop-and-wait mechanism is adopted here. The Binary Phase Shift Keying(BPSK) is used in line-of-sight(LOS) and non-line-of-sight(NLOS) on-body channels while 16-ary Quadrature Amplitude Position Modulation(QAPM) is used to support the high data rate applications in in-body channel. The simulation results show that cooperative communication achieves the lowest average end-to-end delay regardless of any S-D distances. However, when the S-D distance is long sufficiently, the average end-to-end delays of cooperative and 2-hop communications are approximately the same. Furthermore, the average end-to-end delay in case of varying the transmission power is also investigated. It is shown that increasing the transmission power significantly improves the average end-to-end delay, especially in in-body channel.