Medium Access Techniques in Ultra-wideband Ad Hoc Networks

∗ This paper describes work undertaken partly in the context of the IST-2001-34157 Power aware Communications for Wireless OptiMised personal Area Network (PACWOMAN). The IST program is partially funded by the EC. Abstract--Short-range wireless systems have recently gained a lot of attention to provide seamless, multimedia communications around a user-centric concept in so called wireless personal area networks (WPAN). Ultrawideband (UWB) technology presents itself as a good candidate for the physical layer (PHY) of WPAN, both for high and low data rate applications. Although the PHY issues for UWB in WPAN environments have been extensively studied, the problems related to the medium access techniques remain largely unexplored, especially for targeted WPAN scenarios. In this paper, we consider time-hopping spread spectrum (TH-SS) UWB communication system and discuss how to design medium access techniques in order to achieve efficient resource sharing in WPAN environments. We evaluate throughput performance by computer simulation in multi-network scenario, and discuss the impact of TH parameters on the throughput performance. Furthermore, we propose a link adaptation mechanism which can adapt TH parameters according to interference conditions among collocated WPANs. This mechanism aims to maximize the throughput achieved by WPANs while keeping the robustness with respect to the basic timing mechanisms used in the TH-SS communications.