A Power Adjustment Approach for Multi-channel Multi-AP Deployment Using Cognitive Radio Concept

The explosive growth in wireless network over the last few years resembles the rapid growth of the internet within the last decade. The increasing popularity of IEEE 802.11 demands enhancement in network performance. WLAN uses frequency spectrum for providing wireless access to nomadic nodes which is in fact a very scarce resource. One common issue in deployment of a multi-channel multi-AP (access point) wireless network is interference. Interference can be minimized by adjusting the transmission power. This paper focuses on transmission power adjustment of APs by using the concept of cognitive radio. The approach requires RSSI (Received Signal Strength Indication) information to be sent by all the mobile WSs (workstations) in the coverage area to the associated AP at regular intervals to keep the AP updated about their distance. Depending on the current position of WS, AP’s power transmission level is adjusted (increased, decreased, remains same, transmission stopped). During adjustment of power level of the AP, cognitive radio concept is used to avoid the power level to reach beyond a maximum level so as to minimize the problem of interference. Each AP in the network considers itself to be secondary users as in a cognitive network and keeps it power level within a limit such that other APs (taken as primary users) do not face interference.