Joint synchronization and channel estimation for the uplink coordinated multi-point systems

This paper addresses the reference sequence (RS)-aided joint synchronization and channel estimation for the uplink of coordinated multi-point (CoMP) systems based on the minimum mean square error (MMSE) criterion. Considering the highly complex grid-search process involved in the MMSE estimation, the alternating minimization method is employed to simplify the MMSE cost function such that the multiuser carrier frequency offset (CFO), sampling timing offset (STO), and channel frequency response (CFR) can be estimated in an iterative approach which is more feasible for practical systems. Moreover, with the delicately designed orthogonal RS, multiuser RS interference can be effectively suppressed. Finally, the performance of the joint estimator is analytically investigated from the perspectives of estimation error and Cramer-Rao bound (CRB). Simulation results indicate that the proposed scheme can achieve almost ideal performance for both synchronization and channel estimation.