The capacity of downlink multiple-input multipleoutput (MIMO) cellular networks is significantly limited by intercell interference (ICI), particularly at cell boundaries. Recently, two types of coordinated multiple point transmission (CoMP) technologies, joint processing and transmission (JPT) and coordinated scheduling and beamforming (CSB), were proposed. These technologies are intended for the latest cellular communication standard in order to improve the performance of cell-edge users who suffer from significant ICI. In this paper, we propose an ICI cancellation technique based on a user selection algorithm for CoMP-CSB. Under partial channel state information (CSI) and no data sharing condition, each base station (BS) concentrates more on the direction of interference to the adjacent cell's users, during the user selection process. Unlike prior concepts for a single-cell environment, in which each BS generates a precoding matrix for selected users to be served, the proposed technique considers the effects of interference to users located in adjacent cells. Although there are obvious trade-offs between ICI mitigation and the number of simultaneous scheduled users in terms of system capacity, the simulation results demonstrate that our proposed algorithm achieves higher sector throughput and is more robust against ICI if the system is limited by interference. Furthermore, through simulation we are able to obtain the preferred option for the coordination distance (R) and the number of degrees of freedom for ICI nulling ( ).Index Terms-MU-MIMO broadcast channel, SDMA, transmit beamforming, zero-forcing, coordinated multiple point transmission (CoMP), BS-cooperation.

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A femtocell is a small cellular base station, typically designed for use in a home or small business. The random deployment of a femtocell has a critical effect on the performance of a macrocell network due to co‐channel interference. Utilizing the advantage of a multiple‐input multiple‐output system, each femto base station (FBS) is able to form a cluster and generates a precoding matrix, which is a modified version of conventional single‐cell block diagonalization, in a cooperative manner. Since interference from clustered‐FBSs located at the nearby macro user equipment (MUE) is the dominant interference contributor to the coexisting networks, each cluster generates a precoding matrix considering the effects of interference on nearby MUEs. Through simulation, we verify that the proposed algorithm shows better performance respective to both MUE and femto user equipment, in terms of capacity.

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