A new frequency channel assignment algorithm in high capacity mobile communication systems

Abstract

A new algorithm for frequency channel assignment in mobile radio communication is proposed. The algorithm uses flexible fixed channel assignment which enables the calls having all their nominal channels busy to borrow channels from the neighboring cells provided that co-channel interference will not result. The borrowed channel cannot be used in three interfering cells; therefore reassignment strategy is used when a call is terminated on a nominal channel to switch a call in progress in a borrowed channel to that nominal one and set free the borrowed channel in the three interfering cells. Thus the traffic carried on borrowed channels is minimized. Also different call switching strategies are proposed to give priority to some channels to be used by the nominal cells and other channels to be borrowed by neighboring cells. These strategies considerably reduce the blocking probability. A simulation study of the algorithm was carried out on 49 hexagonal zones having uniform traffic density. Also a combined telephone and dispatch traffic was included in the simulation study. The results showed that the new algorithm is better than the other channel assignment schemes. This can be applied in high capacity mobile communications systems to utilize the spectrum efficiently.