Channel Assignment in Wireless Local Area Networks

The tremendous growth of wireless networks requires an efficient use of the scarce radio spectrum allocated to wireless communications. However, the main difficulty against an efficient use of radio spectrum is given by interferences, caused by unconstrained simultaneous transmissions, which result in damaged communications that need to be retransmitted leading to a higher cost of the service. Interferences can be eliminated (or at least reduced) by means of suitable channel assignment techniques. Indeed, co-channel interferences caused by frequency reuse is one of the most critical factors on the overall system capacity in the wireless networks. The purpose of channel assignment algorithms is to make use of radio propagation loss characteristics to increase the radio spectrum reuse efficiency and thus to reduce the overall cost of the service. The channel assignment algorithms partition the given radio spectrum into a set of disjoint channels that can be used simultaneously by the stations while maintaining acceptable radio signals. By taking advantage of physical characteristics of the radio environment, the same channel can be reused by two stations at the same time without interferences (co-channel stations), provided that the two stations are spaced sufficiently apart.