SUMMARYIn this paper, we investigate the energy efficiency of an incremental relay based cooperative communication scheme in wireless body area networks (WBANs). We derive analytical expressions for the energy efficiency of direct and cooperative communication schemes taking into account the effect of packet error rate. The following communication scenarios specific to a WBAN are considered: (i) in‐body communication between an implant sensor node and the gateway, and (ii) on‐body communication between a body surface node and the gateway with line‐of‐sight (LOS) and non‐LOS channels. The results reveal a threshold behavior that separates regions where direct transmission is better from regions where incremental relay cooperation is more useful in terms of energy efficiency. It is observed that, compared with direct communication, incremental relay based cooperative communication schemes improves the energy efficiency significantly. Further, cooperation extends the source‐to‐destination hop length over, which energy efficient communication can be achieved as compared with direct communication. We also observe that, for both direct as well as cooperative transmission schemes in error prone channels, an optimal packet size exists that result in maximum energy efficiency. Copyright © 2013 John Wiley & Sons, Ltd.

In this paper, we investigate packet size optimization to improve energy ef ciency of cooperative Wireless Body Area Networks (WBANs). We present models for the packet error rate and the energy ef ciency of ARQ scheme for direct as well as cooperative communication scheme. We then consider the packet size optimization for both the transmission schemes. The theoretical analysis and the numerical evaluations reveal that cooperative transmission scheme improves the energy ef ciency, increases the optimal payload packet size, and extends the hop length, as compared to direct communication for all scenarios of WBANs that includes both in-body as well as on-body propagation models.

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Selection of the most energy-efficient modulation scheme is vital for wireless body area networks (WBANs) for improving the network lifetime. In this paper, we investigate the performance of various modulation schemes specified by IEEE 802.15.6 WBAN standard, in terms of energy consumed for successfully transferring one packet from the sensor node to the hub. Assuming a contention-free MAC protocol, we present an analytical model for computing the energy consumption for a given modulation scheme both for uncoded transmission as well as transmission using Bose-Chaudhuri-Hocquengham (BCH) codes; the coding scheme specified by IEEE 802.15.6 for WBAN. The following communication scenarios specific to a WBAN are considered: (i) in-body communication between invasive devices and hub and (ii) on-body communication among non-invasive devices and hub with line-of-sight (LOS) and non-LOS (NLOS) channels. The results show that the use of higher order differential phase shift keying (D8PSK)-based modulation schemes results in significant reduction of total energy consumption. When BCH codes with various code rate specifications are used, total energy consumption remains lower for the higher order modulation schemes. The energy consumption is further reduced when non-coherent frequency shift keying (NC-MFSK) is employed as an alternate modulation scheme instead of differential PSK schemes.