© Institute for Computer Sciences, Social Informatics and Telecommunications Engineering 2015 N. Mitton et al. (Eds.): AdHocNets 2015, LNICST 155, pp. 29–41, 2015. Doi: 10.1007/978-3-319-25067-0_3 Optimizing the Placement of ITAPs in Wireless Mesh Networks by Implementing HC and SA Algorithms Liqaa Nawaf, Christine Mumford, and Stuart Allen Cardiff University, Computer Science, Cardiff, UK {NawafLF,MumfordCL,AllenSM}@cardiff.ac.uk Abstract. In this paper, we present novel heuristic improvement (move) opera- tors for the design of Wireless Mesh Networks (WMN), and demonstrate their efficiency within simple Hill Climbing (HC) and Simulated Annealing (SA) frameworks. The management cost of Internet Transit Access Points (ITAPs) in WMN is significant, so it is crucial to minimize the number of ITAPs required whilst maintaining an acceptable quality of service (QoS). Using a single objec- tive method, we investigate algorithms to make informed placement decisions based on the grid size, wireless range connectivity, wireless link capacity and user demands. The experimental results showed the efficiency of the proposed combination of move operators. Keywords: wireless mesh network, move operators, optimization. 1 Introduction Wireless Mesh Networks (WMNs) are a promising approach to provide ubiquitous broadband internet access due to their great potential in supporting multimedia appli- cations. WMNs, an emerging technology, may bring the dream of a seamlessly con- nected world into reality. In a WMN, a limited number of Internet Transit Access Points (ITAPs) serve as gateways or bridges to the Internet, and are deployed across a community. Individual houses within the community are equipped with antennae and low cost routers (namely, mesh routers) which perform two roles: 1) to service the traffic in and out of the house to the individual laptops and other devices (that is, to the mesh clients), and 2) to provide a link in a multi-hop wireless backbone that is formed between the houses to cooperatively route traffic throughout the neighbour- hood, communicating with the Internet through the ITAPs. Such a multi-hop structure dramatically reduces the number of ITAPs needed, which can result in massive sav- ings in cost. The networking infrastructure is decentralized and simplified because each node need only transmit as far as the next node. An ITAP will share its Internet connection wirelessly with all houses in its vicinity. Those houses then share the con- nection wirelessly with the nodes closest to them. Large or small networks can be created in this way to serve small rural communities, or millions of residents in a city. In this paper, we address the ITAP placement problem, which involves determining the numbers and locations of ITAPs that are required to service the needs of a community. This situation is easily modelled using graph theory. In wireless