Joint Relay Selection and Subcarrier Allocation for Multi-Carrier AF Relay Assisted Multi-Access Networks

Cooperative communication is a promising technique, which can greatly improve the performance and extend the coverage of cellular networks. In this paper, the resource allocation problem is investigated for multi-carrier amplify-and-forward (AF) relay assisted multi-access networks with multiple users and subcarriers. The joint relay selection and subcarrier allocation problem is formulated as a combinatorial optimization problem so as to minimize the outage probability with fairness assurance. To solve this problem, we propose a constraint maximum H-matching approach, which is based on a correlated random bipartite graph (RBG) formulation. By analyzing the properties of H-matching method on correlated RBG, the tight approximation of outage probability will be obtained in closedform formulas. By deriving the diversity-multiplexing tradeoff, it is shown that the proposed approach achieves the same frequency and cooperative diversity as if the network has only one user, while all of the users fairly share the multiplexing gain at the same time. The proposed H-matching method also enjoys a sublinear computation complexity for parallel implementations. Numerical results verified the theoretical derivations and optimality of the proposed approach.