Optimisation of SlotTime for a single-radio Mid-Range Multi-hop Wireless Mesh Network

Abstract

This paper presents the business context and results of an optimisation exercise for a single-radio mid-range multi-hop wireless mesh network for the provision of VoIP services. This WiFi mesh network physically covers 30 square kilometres in rural South Africa with a dozen solar-powered nodes. The firmware multiplexes the single radios in adhoc and infrastructure modes, essentially providing a distributed hotspot that can be used for WiFi-based Asterisk attachment in addition to POTS handsets via an ATA adapter in a node. We argue that this architecture is comparable yet cheaper and easier to install and maintain than multi-radio systems with directive antennas. Measurement of a range of values revealed a SlotTime setting that maximises throughput by 115%. We leverage this finding to argue a business case for a ground up community-based mesh network like this one; to provide a win-win situation for local residents and operators with free internal calls backed up by revenues from low cost voice breakout, Internet services and solar-based mobile phone charging. Our novel approach offers an accessible and affordable business model based on increased traffic volume from residents in a rural area that have mobile connectivity yet cannot afford to use it. The optimised architecture described herein offers an attractive and complementary alternative.