One of the most important challenges exists in WiMAX network is the problem of non-line-of-sight. In this kind of link, the problem is loss of power caused by diffusion of waves into the building and access to coverage extension.one of the solution of this trouble is using relays in the network which improves signal’s quality. IEEE 802.16j standard method that is related to multi hop network is designed for this purpose. In addition, one of the key points in multi hop networks is the places in which relays are located in order to increase the capacity. A great deal study has been done in this area, so far. In these researches, the criterion of finding the best position of relays in network is network’s capacity based on physical layer, while scheduling algorithm and resource allocation is one crucial factor in network’s capacity which is neglected in the studies. So, in this dissertation, common scheduling algorithms are investigated to estimate the influence of them on finding the location of relays. Since, most of the algorithms have a weak point, two algorithms were firstly put forward and then a procedure is proposed to find the place of relays. In the presented method, in order to determine the place of relays, the properties of both medium access control layer and physical layer are considered. It should be taken into account that in majority of studies in the area of scheduling and resource allocation algorithms, for the purpose of increasing network’s capacity, it is assumed that coherence time of user channel is more than time length of a frame , however, it may not be correct. Consequently, in proposed scheduling algorithms and resource allocation, the situation of physical link of operators is specially considered. Furthermore, these algorithms are useful when coherence time of user channel is less than time length of a frame. Key words: multi hop network, relay, scheduling algorithm and resource allocation, coherence time.