A proactive routing protocol for multi-channel wireless ad-hoc networks

Wireless mobile ad-hoc networks consist of a collection of peer mobile nodes that form a network and are capable of communicating with each other without help from stationary infrastructure such as access points. The availability of low-cost, commodity network interface cards (NICs) has made the IEEE 802.11 medium access control (MAC) protocol the de facto MAC protocol for wireless mobile ad-hoc networks, even though it is not optimal. The IEEE 802.11 MAC protocol is designed to have stations share a single channel in a given network. However, many of the IEEE 802.11 physical (PHY) layer specifications define multiple channels and allow the simultaneous, non-interfering use of some of these channels. Therefore, multiple communications can occur at the same time, offering the opportunity to increase the effective network capacity.;We present an innovative routing protocol that utilizes multiple channels to improve the performance of wireless ad-hoc networks. The basic idea of the protocol is to use multiple channels so that multiple useful transmissions can occur simultaneously, thus increasing network capacity. The proposed scheme requires minor changes to existing proactive ad-hoc routing protocols and no modifications to the current IEEE 802.11 MAC protocol. To reduce inefficiencies due to periodic updates in the proactive routing protocols, the proposed scheme divides the network layer into control and data planes. Nodes send routing updates using the control channel and user packets using the data channel.;To demonstrate the multi-channel routing scheme, we extend the Destination-Sequenced Distance-Vector (DSDV), Open Shortest Path First-Minimal Connected Dominating Set (OSPF-MCDS), and Optimized Link State Routing (OLSR) protocol to multiple channel (MC) versions, denoted as DSDV-MC, OSPF-MCDS-MC, and OLSR-MC, respectively. Simulation results for DSDV-MC, OSPF-MCDS-MC, and OLSR-MC are presented and experimental results for OLSR-MC are presented. Simulation results indicate that DSDV-MC and OSPF-MCDS-MC effectively exploit multiple channels to improve network capacity. Goodput, the throughput considering only useful error-free packets, increases with an increased number of available channels as the number of nodes and network load increase in both single-hop and multiple-hop networks. Experimental results with OLSR-MC also support that the proposed scheme increases network capacity without modification to the MAC protocol in a real implementation.;Although simulation and experimental results show that proposed scheme improves network capacity by exploiting multiple channels, problems exist with channel distribution. We introduce a new metric, the Channel Distribution Index (CDI) to investigate these issues. The CDI indicates the fairness of the channel distribution. We identify the channel convergence problem, where a particular channel is overutilized, and propose a channel reallocation scheme to mitigate the impact of the channel convergence problem using the CDI.