Research On3D MIMO Channel Modeling

With the development of wireless communication, higher requests are put forwardon the transmit rate and throughput of a system. Because MIMO technology has a notableadvantage in capacity, it has been received more in-depth research,and becomes the keytechnology of next generation communication. MIMO technology can make full use ofspatial characteristic, and improve the system capacity without increasing transmissionpower and bandwidth. However, the promotion of capacity has a close relationship withthe wireless communication channel. At present, the research on MIMO channel model isprimarily based on two-dimensional plane, the statistics of electromagnetic wavepropagation focus on horizontal angle.In order to simulate the real communication channel environment more accurately, a3D MIMO channel model is studied in this paper. In the new model, an elevation angle isadded to make the channel transmission coefficients conform to the real communicationscene exactly. The modeling method of3D MIMO is statistical geometric stochasticchannel model, which is the same as the modeling method of SCM channel proposed by3GPP and WINNERⅡ channel proposed by European Union.The3D MIMO channel model studied in this paper is on the basis of WINNERⅡchannel, we first obtain the statistical results of channel parameters, then generate largescale parameters and small scale parameters randomly according to these statisticalproperty, and use them to calculate the channel transmission coefficients. WINNERⅡchannel has provided many measurement results and probability density functions ofhorizontal angle in several communication scenes, but little statistical data of elevationangle, so the elevation angle used in this paper is assumed to obey a certain distribution.The3D MIMO channel that introduce elevation angle is more accurate, and the antennaresponse should be reappraised, so an algorithm to construct the3D antenna field patternaccording to its horizontal and vertical directional pattern is also introduced in this paper.The model of antenna array is in accordance with that in WINNERⅡ channel, which usesthree coordinate systems to express the relationship of electromagnetic wave directionand antennas. On the basis of3D MIMO channel model, simulations are conducted to verify thevalidity of the new channel. The channel properties, such as fading characteristics intime-domain, channel envelope, correlation and capacity are all analyzed here. Wecompare the channel characteristics under different parameters, and finally verify thereliability of3D MIMO channel model combing with theoretical analysis. Meanwhile,simulations of precoding performance in different channels are analyzed, three linearprecoding schemes are considered in the paper: zero-forcing, block diagonalization andmaximize signal to leakage and noise ratio. Results show that under the same simulationconditions, different channel models can lead to different system performance, it alsoillustrates the significant influence of channel model to the system performance,therefore, confirm the necessity of3D MIMO channel modeling.