Energy Efficient Cooperative Communications for Wireless Body Area Networks

It is expected that Wireless Body Area Network (WBAN) will greatly improve the quality of our life because of its myriad applications for our human beings. However, one of the challenges is to design energy efficient communication protocols to support the reliable communication as well as to prolong the network lifetime. Cooperative communications have the advantage of spatial diversity to combat multipath fading, thus improving the link reliability and boosting energy efficiency. In this thesis, we investigate the energy efficient cooperative communications for WBAN. We first analyze the outage performance of three transmission schemes, namely direct transmission, single relay cooperation, and multi-relay cooperation. To minimize the energy consumption, we then study the problem of optimal power allocation with the constraint of targeted outage probability. Two strategies of power allocation are considered: power allocation with and without posture state information. Simulation results verify the accuracy of the analysis and demonstrate that: 1) power allocation making use of the posture information can reduce the energy consumption; 2) within a possible range of the channel quality in WBAN, cooperative communication is more energy efficient than direct transmission only when the path loss between the transmission pair is higher than a threshold; and 3) for most of the typical channel quality due to the fixed transceiver locations on human body, cooperative communication is effective in reducing energy consumption

Cooperative beacon-free MAC layer for body area networks

International audienc

Analysis of a cooperative beacon-free MAC layer for Body Area Networks

International audienceThis paper discusses medium access control (MAC) issues for body area networks (BANs), relying on an Ultrawide Band Impulse radio (UWB-IR) physical layer. BANs are bound to be coordinated by a powerful device like a smart-phone, which manage the access of the nodes on a beaconed fashion. But in some particular situations, the coordinator may disappear and/or be not yet available. These transient situations shall be addressed and a beacon-free medium access control is desirable. We propose a beacon-free MAC layer, based on a collaborative version of the preamble sampling approach. This is designed to address the European regulatory low duty cycle (LDC) constraint, which UWB devices must comply to. A Markov chain model is given to describe the protocol. By means of simulations, we first show that the model is accurate and secondly that this protocol looks able to manage various BANs configurations