Cross-Layer Congestion Control and Scheduling in Multi-Hop OFDMA Wireless Networks

In this paper, we consider joint end-to-end congestion control and multiuser scheduling in multi-hop wireless networks, where orthogonal frequency-division multiple access (OFDMA) is the air interface. Compared to its single-channel counterpart, this problem is significantly more challenging because subchannel assignment and power allocation for all nodes and network traffic need to be jointly optimized. To avoid cochannel inference, we first consider an OFDMA subchannel separation problem in multi-hop communication scenarios. Then, we address this cross-layer optimization problem by decomposing it into two subproblems: a TCP layer congestion control for traffic allocation and a weighted scheduling for OFDMA subchannel assignment and power control. Observing that the scheduling for multiuser OFDMA in multi-hop wireless networks is inherently NP-hard, we propose a low-complexity algorithm that ensures a solution converging to the optimum. The performance of the algorithm is demonstrated through simulations.