Cooperative routing with relay assignment in multi-radio multi-hop wireless networks

Cooperative communication (CC) for wireless networks has gained a lot of recent interests. With its ability of mitigating fading by exploiting spatial diversity, CC has the potential to significantly increase the capacity of wireless networks. However, most of the works on CC are limited to single radio wireless network. To demonstrate the benefits of CC in multi-radio multi-hop wireless network, this paper studies a joint problem of multi-radio cooperative routing and relay assignment to maximize the minimum rate among a set of concurrent communication sessions. We first model this problem as a mixed integer linear programming (MILP) problem and prove it to be NP-hard. Then we propose a centralized algorithm and a distributed algorithm to solve the problem. The centralized algorithm is designed within a branch-and-bound framework by using the relaxation of the formulated MILP, which can find a global (1 + ε)-optimal solution. Our distributed algorithm includes two sub-algorithms: a cooperative route selection sub-algorithm and a fairness-aware route adjustment sub-algorithm. Our simulation results demonstrate the effectiveness of the proposed algorithms and the significant rate gains that can be achieved by incorporating CC in multi-radio multi-hop networks.

I. Introduction

In recent years, we have seen significant research interests in exploiting cooperative communications (CC) over distributed antennas to improve the transmission performance [1]. Taking advantage of the broadcast nature of wireless channels, one or more multiple neighboring nodes can serve as relays and forward overheard packets from a sender to its target receiver, which can combine multiple copies of the packet to decod^e the original one. Therefore, by exploiting the inherent spatial and multiuser diversities, the cooperative communication technique can efficiently improve the network performance. This makes cooperative communications an emerging technique for future wireless networks.