Distributed Cooperative Routing for UWB Ad-Hoc Networks

Abstract

This conference paper proposes and investigates a new distributed cooperative routing strategy that can be adopted to forward data in the ultra wide band (UWB) ad-hoc network via a multi-hop route with the best instantaneous quality. The strategy combines the physical (PHY) and medium-access-control (MAC) layer mechanisms to select the best route from available ones in a cooperative and distributed way. Using an example of the parallel two-hop relay network where data from a source node can be forwarded by several possible relays to the destination node, we study two related issues: First, we devise a new estimation algorithm for the UWB link received signal-to-noise ratio (SNR) that is used to determine the UWB link quality. The estimation algorithm is unbiased with estimation errors significantly lower than the reported algorithms in literature. Second, we propose a new distributed cooperative routing scheme. Each relay node uses an enhanced carrier sensing with deterministically mapped backoff period as the MAC protocol. The back-off period is chosen by each relay such that the higher the quality of the associated source-relay-destination route, the shorter the back-off time. Simulation results show that even without any feedback about the relay- destination link quality from the destination node to relays and using only its statistical information, the proposed scheme still has up to 3 dB improvement in performance as compared to the random routing. When having 1-bit such feedback, the proposed scheme can achieve full diversity and the overall performance is only 2 dB away from that with full-precision feedback.