Multi-Relay Relay Communications in the Presence of Phase Noise and Carrier Frequency Offsets
Abstract: Impairments such as time varying phase noise (PHN) and carrier frequency offset (CFO) result in loss of synchronization and poor performance of multi-relay multi communication systems. Joint estimation of these impairments is necessary in order to correctly decode de the received signal at the destination. In this paper, we address spectrally efficient multi multi-relay relay transmission scenarios where all the relays simultaneously communicate with the destination. We propose an iterative pilotpilot aided algorithm based on the ex expecta'on pecta'on condi'onal maximiza'on for joint es'ma'on of mul'path channels channels, Wiener PHNs, and CFOs in decode-and-forwarddecode based mul'-relay relay orthogonal frequency division mul'plexing systems. systems Next, a new expression of the hybrid CramĂŠr CramĂŠr-Rao lower bound (HCRB) CRB) for the multi-parameter multi estimation problem is derived. Finally, an iterative receiver based on an extended Kalman filter for joint data detection and PHN tracking is employed. Numerical results show that the proposed estimator outperforms existing alg algorithms orithms and its mean square error performance is close to the derived HCRB at different signalsignal to-noise noise ratios for different PHN variances. In addition, the combined estimation algorithm and the iterative receiver can significantly improve average bit-error bit rate (BER) performance compared with existing algorithms. In addition, the BER performance of the proposed system is close to the ideal case of perfect channel impulse responses, PHNs, and CFOs estimation.