IMPORTANT: Integrating Multi-rate caPability into Opportunistic Routing in uwb-based Ad hoc NeTworks

Ultra-wideband (UWB) communications has emerged as a burgeoning technology for high data rate wireless personal area networks (WPANs). In this paper, we exploit the integration of rate assignment into opportunistic routing under a required QoS, i.e., end-to-end packet error rate (PER), for improving the performance of UWB-based WPANs. Opportunistic routing has been proposed for ad hoc networks. In this type of routing protocols, instead of determining a static path ahead of time, the path is constructed dynamically. The protocol exploits the broadcast nature of wireless communications by allowing packet forwarding to be done by the closest recipient to the destination. Several works showed that opportunistic routing improves network performance. None of these works studied the integration of rate assignment into opportunistic routing while satisfying a target QoS. In this paper, we formulate and study this integration. In our setup, we aim at determining the required number of retransmissions in opportunistic routing and the transmission rate in each retransmission such that the required delivering time for a sent packet is minimized while at the same time a certain end-to-end PER is satisfied. We show that this problem is NP-hard. Accordingly, we propose an approximate solution called IMPORTANT. Extensive simulations over a UWB-based WPAN show that IMPORTANT achieves high performance relative to different techniques (21–48% throughput improvement).