Routing in Multi-Channel Wireless Ad-hoc Networks: OSPF-MCDS-MC

Abstract

The availability of low-cost network interface cards (NICs) has made the IEEE 802.11 medium access control (MAC) protocol the de facto MAC standard for wireless mobile ad-hoc networks. Although the IEEE 802.11 MAC protocol is designed to have stations share a single channel in a network, many of the IEEE 802.11 physical (PHY) layer standards define multiple channels and allow the simultaneous, non-interfering use of some of these channels. Therefore, simultaneous communications can occur through different channels, offering the opportunity to increase effectivenetwork capacity. We present an innovative routing protocol that utilizes multiple channels to improve performance in a mobile ad hoc network. The key feature of the protocol is that nodes can effectively use multiple channels for simultaneous useful transmissions, thus improving networkcapacity. The proposed scheme requires minor changes to existing proactive or table-driven routing protocols and no modifications to current the IEEE 802.11 MAC protocol. To mitigate the overhead of periodic updates in proactive routing protocols, the proposed scheme divides the network layer into control and data planes. To demonstrate the multi-channel routing scheme, we extend the OSPFMCDS routing protocol to a multi-channel version, OSPFMCDS- MC or, more simply, OMM. Simulation and experimental results indicate OMM successfully exploits multiple channels to increase network capacity. The protocol allows the network goodput to increase in proportion to the number of available channels, even as the number of nodes and network load increase, in both single-hop and multiple-hop networks. We also present a prototype implementation for experimental validation of the proposed multi-channel routing protocol scheme. The implementation includes the multi-channel routing protocol and a virtual interface module, which acts as a buffer for outgoing packets and performs channel-related functions, such as channel selection and switching, while ensuring portability.