Experimental Investigation of TDD Reciprocity-Based Zero-Forcing Transmit Precoding
The authors describe an implementation of TDD reciprocity based zero-forcing linear pre-coding on a wireless testbed. A calibration technique which self-calibrates the base-station without the need for help from other nodes is described. Performance results in terms of downlink channel estimation error as well as Bit Error Rate (BER) and Signal to Interference Noise and Distortion Ratio (SINDR) are presented for a scenario with two base-stations and two mobile stations, with two antennas at the base-stations and a single antenna at the mobile-station. The results show considerable performance improvements over reference schemes (such as maximum ratio transmission).