Overview

Introduction

In this project, we exploit the benefit of multiple orthogonal channels in multi-hop wireless access networks (MWANs) from the aspect of network topology control. Between medium access control and network layers, we propose a novel protocol named Multi-channel coordinated Temporal Topology control (MOTTO). Controlling the network temporal topology through coordinated multi-channel assignments, MOTTO decomposes the contending multi-hop traffic in a single channel MWAN into small groups of single hop traffics over different channels, epochs and spaces. Such network decomposition significantly reduces the traffic contention and leads to significant capacity improvement in MWANs.

We propose a novel protocol named Multi-channel coordinated Temporal Topology control (MOTTO), which significantly improves the network capacity of MWANs by utilizing frequency diversity in concert with spatial and temporal reuse. Designed for single half-duplex transceiver device with no changes to the existing MAC/routing protocols and hardware, the proposed methodology has a great potential to being deployed in existing systems that provide multiple non-interfering orthogonal channels (e.g., IEEE 802.11b has 3 non-overlapping channels and 12 channels for IEEE 802.11a).

Our scheme assumes a single half-duplex radio per node and can be implemented in software over standard off-the-shelf wireless Network Interface Cards (NIC) without changes to MAC and network layers. Simulation results show that MOTTO significantly improves network performance in a number of MWANs scenarios. We observe that a multi-channel wireless network shows time-varying virtual topology as the wireless nodes maneuver from one channel to another. We use the term “temporal topology” to describe the virtual topology of the multi-channel network during a period of time when the nodes communicate at their current channel. Controlling the network temporal topology by coordinated channel assignment, MOTTO decomposes the contending multi-hop traffic in a single channel MWAN into small groups of single hop traffics over different channels, epochs and spaces. Such network decomposition significantly reduces the channel contention and yields a significant performance improvement in MWANs.