Blind Receiver with Joint Channel Shortening, CFO Compensation and Data Detection for 5G MIMO SPC System

The upcoming fifth-generation (5G) systems needs to provide several services with short packets. Due to the property of short packet communication (SPC), reducing the length of cyclic prefix (CP) and length of pilot is an important study. In Darsea et al. [D. Darsea, G. Geli, and F. Verd, "Joint blind channel shortening and compensation of transmitter I/Q imbalances and CFOs for uplink SC-IFDMA systems," Phys. Commun., Vol. 11, pp. 25-35, Jun. 2014], a blind receiver with joint CFO (carrier frequency offset) compensation and channel shortening was proposed for the system with single transmitted antenna and single received antenna. In this paper, we extend the scheme in Darsea et al. (2014) to the multiuser multi-input multi-output (MU-MIMO) environment. We employ the blind system in the receiver which does not need pilot and reduce the length of CP as short as possible. The methods of channel shortening and CFO compensation had been proposed individually. If the duration of CP is not sufficient, we can use equalizer to shorten the channel. The proposed receiver is with four-stage structure. At first, the blind shortening of channel impulse responses (CIRs) is performed. Secondly, the joint estimation and compensation of the CFOs is derived. The third step of the receiver implements signal-to-noise ratio (SNR) maximization. Finally, the fourth stage performs blind detection with constant modulus algorithm (FLOS-CMA).