On the relay placement problem in a multi-cell LTE-Advanced system with co-channel interference

One of the main problems in LTE-A networks is the small rates achieved by cell-edge users. This is due to the adoption of a frequency reuse factor of 1, which aims at increasing the overall capacity. This occurs, however, at the expense of increasing the interference level for cell-edge users. Cooperative communication through the use of relays is an efficient technique to solve this problem. However, careful placement of the relays is a crucial factor in determining the expected capacity gain. In this paper, the relay placement problem in an LTE-A network is studied, taking into consideration the effect of co-channel interference. An optimization framework is proposed to maximize either the total cell capacity or the total cell-edge capacity. Simulation results show a capacity gain factor of 8.027 for cell-edge users due to relay deployment, under 100% cell load in center cell and adjacent cells.