Rate and Reliability Trade-off for mmWave Communication via Multi-point Connectivity

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) problem leveraging Successive Convex Approximation (SCA) with low computational complexity, which admits closed-form solution via iterative evaluation of optimal Karush-Kuhn- Tucker (KKT) conditions. Unlike in the conventional CoMP schemes, the propose 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 splitting the beamformer design to be parallel across the coordinating BSs. For the downlink precoder design, a conservative estimate of the user specific rate is obtained by considering possible combinations of potentially blocked links. In the presence of random blockages, the effective throughput and outage performance of the proposed method significantly outperform several baseline scenarios, hence providing more reliable connectivity.