Link Adaptation in IEEE 802.15.4-Based Wireless Body Area Networks

In this paper we consider an IEEE 802.15.4-based Wireless Body Area Network, where wearable sensor devices are distributed on a body and have to send the measured data to a coordinator. The Carrier Sense Multiple Access with Collision Avoidance algorithm defined by the standard is used as Medium Access Control protocol, whereas different modulation schemes are assumed to be available at the physical layer. We propose a novel Link Adaptation (LA) strategy, where nodes select the modulation scheme according to the experienced channel quality and level of interference. The novelty lays in the fact that in case of large Signal-to-Noise Ratio and low Signal-to-Interference Ratio nodes increase the bit rate, instead of reducing it, as largely done in the works present in the literature. The reduction of the bit rate, in fact, allows to decrease the time the channel is occupied and, therefore, the collision probability. Performance is evaluated in terms of packet error rate and results achieved with and without LA are compared. Results show that the proposed strategy improves performance.