Performance Evaluation of Downlink MU-MIMO Transmission based on Mobile WiMAX System in Computer Simulations and Field Experiments

In this paper, transmission performance for down-link MU-MIMO (Multiuser Multiple-Input Multiple-Output) systems with computer simulation and field experiment are described. The downlink MU-MIMO system is constructed as a transmitter with 6 antennas and receivers with 2 antennas, and the maximum number of users(receivers) is 3. In computer simulation, MU-MIMO transmission system can be realized by using the BD (Block Diagonalization) algorithm, and each user can receive signals without any signal interferences between the other users. BER (Bit Error Rate) performance and channel capacity according to modulation schemes and the number of streams are simulated in spatially uncorrelated and correlated multipath fading environment. In field experiment, downlink throughput on UDP layer are measured on the mobile WiMAX system with Matrix A mode and Matrix B mode developed at Azumino City in Japan. Compared with the simulated and experimented results, the measured maximum throughput performance in downlink has almost the same performance with the simulated throughput. It is confirmed that the experimental mobile WiMAX system for MU-MIMO transmission is actually performed for increasing the total channel capacity of the system.