Single-User SFLC-OFDM System Realization Based on Channel Reciprocity Recovery

Abstract

This paper demonstrates the implementation of a space–frequency line coded-orthogonal frequency-division multiplexing (SFLC-OFDM) system. The SFLC-OFDM system utilizes downlink channel state information at the transmitter, which can be obtained from uplink channel estimation under channel reciprocity assumption between uplink-and-downlink channels. However, in practical implementations, channel reciprocity is violated due to the imperfect synchronization and radio frequency chain mismatch between transceivers. To recover the channel reciprocity, frequency-domain signal processing methods are proposed. Furthermore, a low computational complexity single-instruction multiple-data method is implemented to meet the time constraints in real-time operating systems. The experimental results demonstrate that channel reciprocity can be effectively recovered in the implemented SFLC-OFDM system, resulting in practical communication performance regarding the symbol error rate.

Keywords

• Space–frequency line code (SFLC)
• orthogonal frequency-division multiplexing (OFDM)
• synchronization
• channel reciprocity
• software-defined radio (SDR)
• single-instruction multiple-data (SIMD) method