Resource allocation for relay-aided OFDMA networks with constraints on queue stability

In this paper we consider subcarrier allocation to relay-assisted users in an OFDMA wireless network. The two-hop downlink transmission is modeled as a network of queues in series. We have studied the queue length evolution at each hop and propose a rate control mechanism to stabilize the considered queues. To the best of our knowledge this is the first work that stabilizes the system without sending queue length information that causes extra transmission overhead. The suggested allocation problem aims to maximize the system throughput with respect to the channel condition and the stability requirements. In order to solve the resulting combinatorial problem we apply a time-shared approach and then convert the outcome to binary allocations which is called anti-relaxation mechanism. Since the optimization problem requires exponential computation time, we have proposed a less complex heuristic approach. The extensive numerical trials confirm that the stability control mechanism balances the data arrival and departure rates which is the required condition for queue stability. When time-sharing is not permitted, the heuristic algorithm can guarantee the queue length stability in significantly smaller execution time comparing to the anti-relaxation method.