Joint Estimation of MCFOs and Channel Gains for Two-Way Multi-Relay Systems With High Mobility

This letter proposes space-alternating generalized expectation maximization and expectation conditional maximization-based joint estimation of multiple carrier frequency offsets and channel gains for two-way relay network with multiple relays. The method iteratively updates least square estimates with less time and stable convergence. We adopt discrete prolate spheroidal and Karhunen-Loeve basis expansion models to capture rapid time variations of channel. Proposed estimators result in acceptable performance for very high user mobility (corresponds to long term evolution for railway). The derived Cramer-Rao lower bound is shown to be comparable with MSE performances.