Access Point Placement And Channel Assignment In WLAN

Wireless communication always demand for more bandwidth, increased coverage or range, increased data rate, decreased interference, and lower costs. Today, most AP based WLANs are inefficient in the because of user mobility. Therefore, they end up providing far less total throughput than they should.Designing 802.11 WLANs include two major components: placement of APs in the service areas and assignment of radio frequencies to each AP. Coverage and capacity are some key issues when placing APs in a service area. APs need to cover all users.This work is based on studying the effect of mobile users on channel assignment by first developing a channel-assignment algorithm at the Access Points (APs) of a Wireless Local Area Network (WLAN) in order to maximize Signal-to-Interference Ratio (SIR) at the user level. We start with the channel assignment at the APs, which is based on minimizing the total interference between APs. Then after when users come in we apply load balancing, by decrementing the power of the MCAP (Most Congested Access Point) until the load is balanced. Based on this initial assignment, we calculate the SIR for each user, using MATLAB. From different users'positions a study was conducted on the effect of user's position on channel assignment, using MATLAB.Finally OPNET was used for a study which was conducted on the effect of mobile user on channel assignment by comparing a network with mobile users and a network with fixed users by assigning APs different channels, and it has proven that the algorithm improves the network performance at users'level. The algorithm can be applied to any WLAN, irrespective of the user distribution and user load.