Experimental results of two-way channel estimation technique for coordinated multi-point transmission

This paper presents an experimental setup of a multi-user MIMO linear precoding system. The experimental system consists of a base station with two antennas and two mobile stations. In this system, a two-way channel estimation technique is implemented in which mobile stations just send back the received signals along with their training sequences. In this technique, the base station can obtain the channel coefficients of both the uplink and the downlink. This two-way multiple-input multiple-output channel estimation technique has been proposed and mathematically analyzed in literature. Computer simulation results have been reported to identify the required hardware specifications for amplify and forward operation in mobile stations by examining the bit error rate performance. However, hardware implementation feasibility of this technique is not studied yet. In this paper, feasibility of a multi-user MIMO linear precoding system using two-way channel estimation technique is shown by in-lab experiments.