Nowadays, various types of access-points (APs) and hosts such as dedicated APs, laptop personal computers, and mobile terminals have been used in IEEE802.11 wireless local-area networks (WLANs). As a result, the optimal assignment of holding APs into the network field depending on the host type distribution has become very important to improve the network performance. In this paper, we formulate this holding access-point assignment problem as a combinatorial optimization problem and propose its heuristic algorithm. Because plural non-overlapping channels are available in IEEE802.11 WLANs, we extend the algorithm to finding the channel assignment to the APs such that the total interference among them is minimized. The effectiveness of our proposal is verified through simulations in three instances.