Optimal and Near-Optimal Cooperative Routing and Power Allocation for Collision Minimization in Wireless Sensor Networks

Cooperative communication has gained much interest due to its ability to exploit the broadcast nature of the wireless medium to mitigate multipath fading. There has been considerable research on how cooperative transmission can improve the performance of the physical layer. Recently, researchers have started to consider cooperative transmission in routing, and there has been a growing interest in developing cooperative routing protocols. Most of the existing cooperative routing algorithms are designed to reduce the energy consumption; however, packet collision minimization using cooperative routing has not yet been addressed. This paper presents an optimization framework to minimize collision probability using cooperative routing in wireless sensor networks. We develop a mathematical model and formulate the problem as a large-scale mixed integer non-linear programming problem. We also propose a solution based on the branch-and-bound algorithm augmented with reducing the search space. The proposed strategy builds up the optimal routes from each source to the sink node by providing the best set of hops in each route, the best set of relays, and the optimal power allocation for the cooperative transmission links. To reduce the computational complexity, we propose a near-optimal cooperative routing algorithm, in which we solve the problem by decoupling the power allocation problem and the route selection problem. Therefore, the problem is formulated by an integer non-linear programming, which is solved using the branch-and-bound space reduced method. The simulation results reveal that the presented algorithms can significantly reduce the collision probability compared with the existing schemes.