Study On The Application Of The SDMA Theory In MIMO

The core principle of Multi-input multi-output system (MIMO) is that using spatial degrees of freedom provided by multi-antenna at transmitter and receiver to effectively improve the spectral efficiency, which would enhance the bit rate and quality of wireless communication system. Throughout the research results of MIMO, the majority research concentrated on the mathematical model of MIMO and less on the physical model. It is sure that the mathematical model has the function of "prophet", but all the research results can achieve their maximum value and significance only when applied to the matched physical model. Therefore, It is valuable and significant to study the application of MIMO.MIMO techniques could be split into two groups basically: space-time coding and space-division multiplexing(SDM). The former increase channel capacity(CC) by channel coding, the other achieves CC gain by transmitting same information on independent Rayleigh fading channels (IRFC) constructed by multi-pair of transmitting and receiving antennas. This paper will focus on the study of the application of MIMO SDM.The present MIMO channel capacity formulas are all deduced on the base of Shannon formula, that is, the mathematical model of MIMO. It is need to research the matched physical model if MIMO system is applied to the actual transmission environment. Firstly, it is whether meet the conditions of IRFC for the channel constructed by a pair of transmitting and receiving antennas if the interval between the transmitting antennas isλ/ 2 or 10λ. Then under the Rayleigh flat fading and frequency selective fading surroundings respectively, the channel capacity formula and matching conditions for the physical model are studied. Also, the beam-forming patterns of multi-antenna and its simulation diagram are given in the paper. At last, the application features of RAKE receiver and joint receiver are studied in some application surroundings respectively.Based on the above research, the paper finally proposed the SHPAA system which will introduce phase array antenna(PAA) technology to MIMO system, derived 3-dimensional channel capacity formula of SHPAA system and gave simulation diagram which verified the enhancement of CC.