An effective AP placement scheme for reliable wifi connection in industrial environment

Abstract

As the wireless communication systems provide higher data rates and extended services, especially for mobile users/devices, they replace rapidly the wired ones. However, for some mission-critical applications in industrial environments, the engineers are unwilling to adopt the wireless system because of the low reliability of wireless link in comparison of wired link. A solution for increasing the reliability of wireless system is using backup wireless link(s). In this case, the adequate locations of access points (APs) of the wireless network can be different from those of the single link case. In this paper, we consider mobile devices/systems carrying out very critical missions, by using WiFi in the hostile indoor radio propagation environments (for example, mobile robots in the automated factories). We propose an effective scheme for placing the APs for a given service area, which aims (1) to ensure that a mobile user can maintain at least two simultaneous links with different APs, respectively, on every point of its moving path and; (2) to lessen the number of APs installed in a whole service area. We design a heuristic scheme based on the optimization approach. A practical merit of the proposed scheme is that the channel model and/or the AP coverage are not need to be pre-assumed or pre-measured. For evaluating the performance, the scheme is implemented and tested in a real environment. The experimental results show that the proposed heuristic scheme successfully achieves the design goals and its performance is comparable with that of the theoretically optimal placement.