We consider the channel allocation problem, which is one of the most interesting problems in mobile radio systems. This problem is known to be NP-complete and a couple of heuristic algorithms have been developed. In this paper, we convert the problem into a simpler form through the concept of pattern, a set of cochannel cells. We suggest another algorithm based on simulated annealing for this simplified problem. The algorithm is applied into different benchmark problems that have appeared in the literature. The presented examples illustrate that our method works very well. Computational results using our formulation and simulated annealing algorithm are reported.