Performance Evaluation Of Three Dimensional Mimo System Based On Channel Measurement

Driven by both the development of new services and mobile smart applica-tions, and the need for a ubiquitous and wirelessly accessible cloud platform, wireless data traffic continue experiencing an explosive increase and user de-mand higher mobile data rates. Traditional multiple antenna (Multi-input Mul-ti-output, MIMO) technology is considered as one of the most promising ap-proaches for high data rates and has been widely introduced into Long Term Evolution Advanced (LTE-A) and802.11n communication system in the past decade. However, the traditional MIMO antenna technology research is largely confined to the one-dimensional antenna array system, i.e., base station can only adapt beam signal in the horizontal plane. With the mature of Antenna manufac-turing technology such as active antenna system (AAS),3D (three-dimensional) MIMO technique that extend the scale of MIMO to the vertical plane and do ex-ploit the channel’s spatial degrees of freedom in the elevation dimension can de-crease inter-cell interference, improve throughput and spectrum efficiency fur-ther. Therefore,3D MIMO technique is an effective way to satisfy the great de-mand for high data rate and has become one of the hot spots in standardization study. Based on the channel measurement data, this paper focus on evaluating and analyzing the performance of3D MIMO that actually applied in the real three-dimensional environment, and main work includes:At the beginning, the performance of3D MIMO in the high rise scenario is evaluated. In the high rise scenario, most of the UEs are indoors and located with different elevation levels due to the UEs being on different floors of a building, and this is also coincident with the typical scenarios where3D-MIMO is likely to be deployed. Firstly, we analyze the features of azimuth angular spread and elevation angular spread in the measured high rise scenerio and we can see the mean angle spread in the elevation dimension is less than that in az-imuth dimension on each measured floor. Secondly, the MIMO channel response for different3D antenna configurations is extracted from measured channel ma-trix in the high rise scenario and the corresponding data rates are calculated. The major findings are:For single user MIMO, vertically spaced antennas does bet-ter in transmit beamforming while horizontally spaced antennas stands out in spatial multiplexing for its wider azimuth angular spread. For multi-user MIMO (MU-MIMO), horizontally distributed antennas performs best when users are on the same floor while the combination of closely spaced vertical antennas with widely spaced horizontal antennas is especially more suitable when users are on different floors. Moreover, it is found that for MU-MIMO, the rate increment comes from increase in BS antenna number is limited but increasing the number of users can improve the sum rate effectively. In addition, it is also noticed se-lecting users on different floors for3D MU-MIMO can achieve the best perfor-mance.Secoond, this paper study the performance of3D MIMO in UMa (urban macrocell) scenario. We analyze the channel capacity varies with each meas-urement point and the correlation between the capacity with the channel gain and the angular spread. And then we give the single-user MIMO transmit beam-forming and spatial multiplexing performance under different3D antenna con-figurations for each measurement position in UMa. Finally, for MU-MIMO, the sum rates of the four3D antenna configurations are calculated and compared under different UMa multi-user distribution cases, and the corresponding appli-cation summary in UMa scenario is also presented.