Priority-list-based opportunistic cooperation — a general framework with cost-aware utility

Cooperation can greatly improve the performance of wireless networks, but not all the time. Due to the dynamics of the wireless network and incomplete information, in many cases, only some uncertain opportunities of cooperation can be found. When these situations arise, opportunistic cooperation techniques, such as algorithms for opportunistic routing, opportunistic spectrum sharing etc. have been designed and studied. Although these techniques have been designed for different problems, the fundamental strategies are similar. One of these strategies, studied in this paper, is the use of a priority list to facilitate cooperation. By studying the benefits and costs incurred in the cooperation process, we propose a general framework to calculate and predict the long term benefits and costs of using a priority list for cooperation. We then unify both benefits and costs into a single metric called cost-aware utility (CAU). In this paper, an algorithm with polynomial time complexity is derived to find the priority list which can give the optimal CAU. We analyze and compare the performance of several priority list-based opportunistic methods in the literature with the CAU-based optimal priority list, for an opportunistic forwarding scenario in an IEEE 802.11g network. Our results show that the proposed CAU-based algorithm discovers an optimal priority list that leads to significantly better network performance than other algorithms such as legacy WiFi and AnyCast.