Evaluating dynamic OFDMA subchannel allocation for wireless mesh networks on SDRs.

Orthogonal Frequency-Division Multiple Access (OFDMA) has emerged as an advanced technique to enhance resource utilization and efficiency in infrastructure-based networks. However, its performance in wireless mesh networks is mostly unexplored. In this paper, we practically study the benefits of OFDMA in a scenario with multiple co-located transmitters and receivers without centralized controller by means of the software-defined radio platform WARP. We propose five different dynamic subchannel allocation strategies and compare their performance to that of OFDM as a baseline. Four of these strategies are constrained to be fair with respect to the number of subchannels allocated per communication link, while the fifth always allocates a subchannel to its best possible communication link. By means of testbed experiments with software-defined radios, we show that the overall bit error rate can be reduced by a factor of ten, while the overall channel capacity can locally be enhanced by 10% to 30%. Further, we use the Subchannel Avoidance Gain as a metric to quantify the ability of a dynamic subchannel allocation strategy to avoid subchannel allocations resulting in poor channel conditions.