Clustered Network MIMO and Fractional Frequency Reuse for the Downlink in LTE-A Systems

Interference is one of the major performance limiting factors in MIMO-based cellular systems. A promising interference coordination strategy being studied in 4G LTEAdvanced systems and beyond is Network MIMO. In systems based on Network MIMO, base stations (BSs) are pooled together to form a multi-cell virtual MIMO system and signal processing is done in a coordinated manner. Although the processing capability of BSs and backhaul capacity are improving, performing network MIMO on a global scale is highly complex and unscalable because of the amount of data exchange required. In this paper, a scalable interference coordination strategy of combining clustered network MIMO with fractional frequency reuse (FFR) is proposed for the downlink of a homogeneous LTE-Advanced system. The cell sum rate performance of this new strategy is shown to be comparable to that of global coordination and also significantly better than two existing approaches in the literature.