Joint routing, scheduling and power allocation in OFDMA wireless ad hoc networks

In this paper an OFDMA-based wireless ad hoc network is considered. In addition to the potential of being a source and/or a destination, each node is assumed to be capable of decoding and forwarding its received packets to other nodes in the network. The goal is to determine the optimal data routes, subchannel schedules, and power allocations that maximize a weighted sum rate of the data communicated over the network. Two instances of this problem are considered. In the first instance, each subchannel is exclusively used on one of the links, whereas in the second instance subchannels are allowed to be time shared by multiple links. The first problem gives rise to an NP-hard mixed integer optimization problem that is difficult to solve. In contrast, using a change of variables, the second problem is cast in a convex form, which is amenable to highly efficient interior point solvers. Simulation results suggest that the gain in the weighted sum rate achieved by the relaxation in the second problem over that achieved by the original mixed integer problem is negligible for small networks, and increases with the size of the network.