A novel block-shifted pilot design for multipair massive MIMO relaying

Abstract

We propose a design of block-shifted pilot scheme for the multipair massive multiple-input multiple-output (MIMO) relaying system. The proposed scheme balances the tradeoff between pilot transmission overhead and channel estimation accuracy in scenarios with limited length of coherence time interval, and thereby the system performance is dramatically improved. In the proposed scheme, pilots are properly designed so that they can be transmitted simultaneously with data to decrease channel estimation overheads. By exploiting the asymptotic orthogonality of massive MIMO channels, the source data can be exactly detected from the received signal, and then pilot-data interference can be effectively suppressed with assistance of the detected data in the destination channel estimation. In the block-shifted transmission pattern, the effective data transmission period is extended to improve system throughput. Both theoretical and numerical results confirm the superiority of the proposed scheme to conventional ones in limited coherence time interval scenarios.