Channel loading in private mobile radio networks

Radio traffic congestion occurs in a radio network when too many users simultaneously transmit on the same channel within close geographical proximity. Such congestion can be prevented by imposing channel loading constraints, which restrict the number of users that can operate using the same channel at one instant in time. Channel loading constraints are a variety of non-binary constraint that can be represented as subsets of transmitters which cannot operate on the same channel. This makes the computational cost in generating and storing them significant. In this paper we present an efficient technique for making an assignment when channel loading constraints are imposed. The method is suitable for implementation on large problem instances. We also propose a technique for finding a lower bound on the minimum span of channels required. The methods we introduce are well suited to the channel loading problem as they eliminate the need for explicit generation of the constraints involved.