Optimization of AP placement and channel assignment in wireless LANs

The design of a wireless local area network (WLAN) has an important issue of determining the optimal placement of access points (AP) and assignment of channels to them. WLAN services in the outdoor as well as indoor environments should be designed in order to achieve the maximum coverage and throughput. To provide the maximum coverage for WLAN service areas, AP should be installed such that the sum of signal measured at each traffic demand point is maximized. However, as users connected to an AP share wireless channel bandwidth with others in the same AP, AP placement should be carefully decided to maximize the throughput by considering load balancing among AP and channel interference for the user traffic demand. In this paper, therefore, we propose an approach of optimizing AP placement and channel assignment in WLAN by formulating an optimal integer linear programming (ILP) problem. The optimization objective is to minimize the maximum of channel utilization, which qualitatively represents congestion at the hot spot in WLAN service areas. It is seen from the simulation results that the proposed method finds the optimal AP placement and channels which minimize the maximum of channel utilization.