A cross-layer approach to clustering and relay assignment based on Vehicle Routing Problem

This paper deals with the problem of relay assignment in cooperative networks. We consider a network which consists of N nodes and a single destination. Each node is a potential relay to help other nodes to communicate with the destination. The problem is how to assign some nodes (as relays) to some nodes (as sources) in order to optimize a convenient objective function in the network. To find the optimized topology, we need to feedback the SNR information to a centralized resource allocator. Throughout this paper, we introduce a Vehicle Routing Problem (VRP) formulation for the problem at hand which can be efficiently solved with Binary Integer Programming (BIP). The proposed formulation can solve many clustering and relay assignment problems in a unified framework. Two different scenarios are described to show this flexibility. In the first scenario, only one of the nodes in each cooperating set benefits from the cooperation whereas in the other scenario both nodes benefit. The proposed approach combines a simultaneous optimization of physical and network layers with the cooperative diversity concept. Some scenarios and network configurations are described throughout the paper to show the flexibility of the proposed method.