Performance analysis for resource coordination in a high-density wireless environment

The cochannel overlapping basic service sets (OBSS) wireless interference is unavoidable in a high-density overlapping BSS environment. In order to provide interference-free environment and, at the same time, Quality of Services, centralized resources coordination functionalities particularly in Medium Access Control (MAC) layer are required. The proposed scheme, based on the context of 802.11 WiFi, separates the uplink and downlink transmission into two periods governed by contention scheme and polling scheme respectively. The possible collisions during the synchronized uplink period are avoided because of the natures of contention scheme used. During the downlink period, the grouping assignments, using coloring theory, are carried out based on the topology to divide BSSs into groups and then time spans to avoid collision. The constraint of grouping is that no two overlapping BSSs could be assigned to the same group/time span, so interferences are minimized using time division technique. A complete performance analysis in a number of simulation scenarios is finally presented.