Improving coherence in distributed MISO communication systems with local accelerometer measurements

This paper considers a distributed multi-input single-output (MISO) communication system with two or more transmit nodes and a single receive node. Each transmit node has an independent local oscillator and independent kinematics. The receive node periodically estimates the combined time offset and propagation delay of each transmit node and provides feedback to the transmit nodes to facilitate channel tracking and prediction for coherent transmission and passband signal alignment. In addition to the periodic time offset feedback, each receive node also observes periodic measurements from a local accelerometer and uses these measurements to improve the tracking performance. Continuous-time and discrete-time models are developed for a system with one-dimensional kinematics. Numerical results show that local accelerometer measurements can significantly improve the performance of time offset tracking, consequently improving coherence for distributed transmit beamforming and distributed transmit nullforming and also potentially allowing for reduced feedback rates with respect to the conventional receiver-coordinated feedback-only approach.