Reliable mmWave Communication via Coordinated Multi-Point Connectivity
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The fundamental challenge of mmWave frequency band is the sensitivity of the radio channel to blockage, which gives rise to unstable connectivity and also impacts the reliability of a system. In this paper, we explore the viability of using Coordinated Multi-Point (CoMP) connectivity for robust and resilient downlink communication. We provide a novel iterative algorithm for Weighted Sum-Rate Maximization (WSRM) leveraging Successive Convex Approximation (SCA) with low computational complexity, which admits a closed-form solution via iterative evaluation of the Karush-Kuhn-Tucker (KKT) optimality conditions. Unlike in the conventional Joint Transmission (JT)-CoMP schemes, the proposed precoder design has, per-iteration, computational complexity in the order of base-station (BS) antennas instead of system-wide joint transmit antennas. This is achieved by parallel beamformer processing across the coordinating BSs. Furthermore, for the downlink precoder design, a conservative estimate of the user-specific rates are obtained by considering possible combinations of potentially blocked links, thus providing greatly improved communication reliability. In the presence of random blockages, the proposed schemes are shown to significantly outperform several baseline scenarios in terms of effective throughput and outage performance.
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