Wireless body area networks (WBANs) have revolutionized healthcare by enabling remote supervision, prior detection, and disease interception using invasive and wearable sensor devices. The limited battery capacity of the sensors coupled with the poor channel condition (that may arise from body postures) require cooperative transmission strategies that can prolong the sensors' life time and associated functionalities. Therefore, in this article, a cooperative scheme based on single-stage relaying is presented for spectrum and energy efficiency. The relay operating for two different scenarios, i.e. network coding and hierarchical modulation, is discussed. The general trend for bit error rate (BER) is observed by modeling a Rayleigh faded link catering path loss. The results are further studied for actual channel models, defined in WBAN standard. The effect of hop-length variation on BER and packet error rate (PER) are discussed. Simulation results show that both cooperative schemes outperform direct communication. A hybrid switching scheme is proposed to enhance efficiency.
Joint Hierarchical Modulation and Network Coding for Asymmetric Data Rate Transmission over Multiple-Access Relay Channel
