Implementation issues for the deployment of a WMN with a hybrid fixed/cellular backhaul network in emergency situations

In this paper we present a research project of the research council of St-Joseph University (USJ) at its faculty of engineering (ESIB) in Beirut, Lebanon, in collaboration with professors at INRS-EMT, Montreal Canada. This project aims at addressing the issues of deployment of a Wireless Mesh Network (WMN) on parts of the Lebanese territory, supported by an already installed dense infrastructure of WiFi hotspots (in urban areas), cellular and fixed telecommunications networks. In particular, we wish to address issues of using such networks in emergency situations, where parts of the telecommunications infrastructure have been damaged, with the need to maintain predominantly voice communications and urgent data communications over any available telecommunications infrastructure that is still operational. The architecture that we look at is a two-tier WMN supporting VoIP and data communications between mesh clients and mesh routers (tier 1), with mesh routers either communicating directly between themselves or, in case of overload or priority traffic, via a backhaul network based on the cellular (GPRS/EDGE) or fixed telecommunications network (tier 2). In this paper, we discuss the issues to be addressed in such a scenario, particularly admission control and priorities with limited backhaul resources, radio interference between closely located mesh routers and clients, and other related issues. The structure of the paper is as follows: section the autho gives an introduction to ad hoc wireless networks and WMN; section II the author discusses the migration issues from independent WiFi hotspots to a fully connected two tier WMN, where the backhaul tier may use other types of networks; in section III, we address the issues for emergency scenarios with limited connectivity between mesh routers. In section IV, we present the simulation scenarios to be considered and the planned tests on a prototype network for a WMN that will be deployed at ESIB, Lebanon. We conclude in s- ection V.