Despite several research efforts on multi-radio mesh protocols, designing high-performance multi-radio mesh networks in real-world settings has remained a challenging problem. To design and deploy a high performance multi-radio mesh network in the real-world, we need to satisfy four fundamental design considerations. First, commodity radios require a minimum radio-separation distance (nearly 18 inches) to avoid interference between radios operating in the same frequency band. Given that existing commercial wireless nodes are extremely compact and that 802.11 has two frequency bands, we envision commercial multi-radio deployments to be restricted to dual-radio nodes with radios operating in different frequency bands (802.11a, 802.11b/g). Second, the dual-radio requirement forces the protocol design to jointly address the problems of routing and channel assignment to eliminate intra-path interference and enhance network connectivity. Third, the protocol should find high performance routing paths in the face of competing wireless networks in the environment that cause channel losses, external interference, as well as significant link fluctuations over different time scales. Finally, the protocol should operate in a distributed manner and provide good adaptivity. There are many existing multi-radio proposals that address some but not all of these challenges.
ROMA is a practical and distributed dual-radio mesh protocol that can achieve sustained high end-to-end performance between every node and one or more designated gateway nodes in the face of lossy links, external load and channel fluctuations. Based on detailed evaluations on a 24-node dual-radio mesh testbed, we have seen that ROMA achieves high end-to-end throughput and adapts well to changing network conditions