ONU Placement in Fiber-Wireless (FiWi) Networks Considering Peer-to-Peer Communications

Nowadays, Fiber-Wireless (FiWi) network is proposed as a hybrid access network that integrates optical access networks (e.g., PONs) with wireless access networks (e.g., WMNs) to provide the high bandwidth, cost-efficient and ubiquitous last mile Internet access. In FiWi networks, besides traffic from wireless mesh clients to the Internet, peer-to-peer communication from one wireless client to another wireless client is introduced due to the recent growth of applications such as multimedia transmissions within community areas. In FiWi networks, such peer-to-peer traffic can be carried either through the wireless path within the wireless mesh subnetwork or through the wireless-optical-wireless mode in which traffic firstly goes from the source client to its closest ONU, and then goes to the ONU closest to the destination client through the PON subnetwork and finally reaches the destination client. Such wireless-opticalwireless mode for peer-to-peer communications can alleviate interferences in the wireless subnetwork, thus improving the network throughput. Considering such mode for peer-to-peer communications, ONUs' placement will have great impact on the achievable network throughput in FiWi networks and will be different from the placement when only traffic to the Internet is considered. In this paper, given the distribution of wireless mesh routers, we study where to place K ONUs in FiWi networks so that the overall network throughput can be maximized when peer-to-peer communications are considered in addition to traffic destinated to the Internet. We first formulate the problem and then propose a tabu search (TS) based heuristic to solve the problem. Simulation results show that compared to the random deployment and the fixed deployment which performs well when only traffic to the Internet is considered, the tabu search heuristic has a much better performance.