Cooperative Route In Multi-hop Multi-interface Wireless Network

Cooperative communication for wireless networks has gained a lot of recent interests due to its ability to mitigate fading with exploration of spatial diversity. In multiple user network, the mobile user could share the others’antenna by certain way to cooperative communication, which generate virtual environment like multiple antennas.Because cooperative communication can get spatial diversity gain, improve the performance of mobile communication system and expand the scope of transmission without increasing the complexity of infrastructure, it becomes the research focus of wireless communication and the one of key optimization techniques for next-generation wireless network.In cooperative communication, the source node select suitable relay node to help cooperative communication, how to select the relay node is the key point to improve the network performance. However, most of the works on CC are limited to single radio wireless network without considering route selection. 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, and emphasis in three parts below:1. This paper models joint multi-radio cooperative routing and relay assignment as a mathematical problem. In the multi-radio multi-hop network, every node is equipped with two radios; Then we will depend the capacity and radio number limit to model joint multi-radio cooperative routing and relay assignment as a mathematical problem while there are multiple flows in the network,which objective is to maximize the minimum rate among a set of concurrent communication sessions; At last, we get a mixed integer linear programming (MILP) problem and prove it to be NP-hard.2. We propose a centralized algorithm based branch and bound framework for the MILP. The algorithm branch the original problem to many sub-problems to get optimal solution. In specific implementation, the algorithm gradually approximate the optimal solution by update the upper bound value and lower bound value, when the discrepancy between the upper and lower bound is smaller than a certain decimal, the current integer solution are the optimal solution. Then we will get the cooperative route and relay assignment in the network.3. We propose another distributed algorithm include a cooperative route selection sub-algorithm and a fairness-aware route adjustment sub-algorithm to study cooperative communication. The first sub-algorithm aims to find the optimal cooperative route without considering the radio number limit, which the route have the maximum transmission rate; The second sub-algorithm focus on adjusting the local route which include the overload node. The distributed algorithm find the optimal route for all the sessions and realize the resource allocation in fair way to maximize the network transmission rate. 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.