OFDMA for wireless multihop networks: From theory to practice

Orthogonal Frequency-Division Multiple Access (OFDMA) enables nodes to exploit spatial diversity in Wireless Mesh Networks (WMNs). As a result, throughput improves significantly. While existing work often considers the physical layer only, using OFDMA in a WMN also affects the link and network layers. In particular, multi-hop forwarding may result in severe bottlenecks since OFDMA resource allocations are typically based on local information only. In this paper, we design a practical system that mitigates such bottlenecks. To this end, we allow for resource allocation based on channel and traffic conditions at the physical layer, per-subcarrier coding at the link layer, and per-subcarrier packet segmentation at the network layer. We implement our approach on software-defined radios and show that it provides significant throughput gains compared to traditional schemes.