Channel Assignment, Stream Control, Scheduling and Routing in Multi-Radio MIMO Wireless Mesh Networks

Abstract

Multi-hop wireless mesh networks are designed as a cost-effective solution for last-mile broadband Internet access. Equipping mesh nodes with multiple radios further improves network capacity by using multiple radios to transmit simultaneously on orthogonal channels. In addition, multiple input multiple output (MIMO) antennas have emerged as a physical layer breakthrough for increasing throughput and suppressing interference from neighboring links. These wireless technologies are viewed as the key components in improving the performance of next-generation wireless networks. However, to obtain the full benefits of these technologies, the networking protocols should exploit their capabilities in a systematic way due to their interdependence. In this paper, we provide the first formal study on cross-layer optimization in multi-radio, multi-channel wireless mesh networks with MIMO links. We formulate a framework where data routing at the network layer, link scheduling and channel assignment at the MAC layer, and MIMO stream control at the physical layer can be jointly optimized for maximizing network throughput subject to fairness constraint among mesh nodes. We then present an algorithm in which routing is established on a longer-time scale for system stability, while scheduling, channel assignment and stream control are jointly determined for opportunistic bandwidth access and sharing in time, frequency and space dimensions based on instantaneous channel conditions and traffic dynamics.