Evaluating a TDMA MAC for body area networks using a space-time dependent channel model

Wireless communications for body area network (BAN) applications require an adaptable, dynamic and flexible medium access control (MAC) to cope with a variety of application requirements. The proposed MAC adjusts its communication protocols and the parameters of the IEEE 802.15.4 superframe. It is based on to achieve low power consumption and low latency which are among the key requirements in BAN applications. In this paper, accordingly with measurements made in an anechoic chamber, we first define a BAN channel model useable in network simulations embedding a spatial and temporal dependency using ray tracing techniques. It is applied to the body postures and movements of a walking person. As body posture highly affects the performance of the MAC protocol, we second evaluate the effects of the varying body shadowing in the walking scenario on our MAC protocol performances.

I. Introduction

The progresses in micro-electronics and miniaturization of the last decade have made electronic devices more and more pervasive in people everyday life. In the multimedia and consumer electronics era we are living in, personal assistants or smart phones are made classical and are surrounded by some wireless peripherals carried by their users and bringing extra services and comfort for work and leisure. In parallel, it is now made clear that the new trend for micro-electronics is in the medical and health domains. A Body Area Network (BAN) consists in sets of devices which are placed on or in close vicinity of the body and, optionally, implanted in the body and connected to each others wirelessly for a given application. Therefore, it cannot rely on general purpose wireless technologies and requires specific investigations and optimizations to limit radiated power, electromagnetic field absorption by the user, consumed power, device size, interference susceptibility.