Performance of Mobile MIMO OFDM Systems With Application to UTRAN LTE Downlink

This paper analyzes the performance of multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) technology through the ergodic capacity. The capacity is represented based on the mean of the effective signal-to-interference-and-noise ratio (SINR) values. The asymptotic distribution of the effective SINR in the case of independent and m-dependent quality measures, i.e., post-processed SINRs, is established analytically. The asymptotic distribution is applicable for the size of post-processed SINRs of at least 1000 samples or more and m = 10. The mean value of the effective SINR based on the moment generating function of post-processed SINR is derived. Additionally, the impact of mobility on the system performance is characterized through the ergodic capacity and a system level factor which measures user mobility. The performance of MIMO OFDM system is validated by fully dynamic 3GPP Long Term Evolution network simulations in downlink under realistic mobility scenarios with low (3 km/h), medium (30 km/h) and high (120 km/h) user speeds. The simulations verify that the derived asymptotic distributions of the effective SINR for the independent and m-dependent cases are very accurate in all mobility scenarios. The simulated ergodic capacity show clear loss in the average MIMO spectral efficiency especially in high mobility scenarios.