The impact of environment variation on co-channel interference in WLAN

This paper has investigated how interference can arise in certain scenarios in a typical multi-floor building environment through the utilization of a 3D ray-tracing algorithm. This work has tried to predict any possible co-channel interfering signals and investigated the variability of received signals due to the variation of geometrical-environment factors. The following conclusions were drawn: (1) in multi-floor buildings, for the case where both the user and the interferer are close to the external wall, transmitted and diffracted signals do not contribute significantly, providing the interferer and the wanted user are separated by more than 2 floors. In the presence of nearby buildings, reflected signals could carry enough power to higher floors but this is highly dependent on the distance, constitutive parameters of the materials involved and relative locations of transmitter and receiver. (2) Deterministic models like ray tracing tend to use the reported constitutive parameters from the literature in order to avoid measuring this data for the specific frequencies and sites of interest. However, due to the variety of different chemical compositions of different materials, quoting the data reported from the literature could give rise to significant prediction errors. (3) Co-channel interference is more likely to occur on the NLOS users at the periphery of coverage since the desired signal experiences greater path loss.