An Optimization Approach to Joint Cell, Channel and Power Allocation in Multicell Relay Networks

In this paper, we consider joint resource allocation of a multicell OFDMA-based networks, with fixed two-hop decode-and-forward relay stations. A joint cell, channel and power allocation problem is formulated as an overall optimization problem, where the objective is to maximize the minimum user throughput. Based on previous complexity results for the setting without relays, the overall optimization problem is shown not to be approximable, unless P is equal to NP. We propose a method for solving this challenging problem. First, a feasible cell allocation is obtained, either via greedy allocation or an exhaustive search. Thereafter, the channel and power allocations are alternately updated, either using a heuristic or optimization-based approach while holding the other two allocations fixed. These alternating channel and power allocations are repeated until no further improvement is obtained. The impact of relay stations is investigated by considering a model with relays as well as one without relays. The simulations show that substantial performance improvement can be made by introducing relays. They also indicate, somewhat surprisingly, that the heuristic channel allocation leads to better overall solutions than the corresponding optimization approach in the relay setting. The optimization-based power allocation significantly outperforms the heuristic power approach with as well as without relay stations.