Effect Of Mutual Coupling On The Performance Of MIMO Systems

Performance of MIMO system with12antennas in the outdoor environment with enrichscatters is studied in this paper. Also, mutual coupling effect of antennas on the performance ofMIMO system is discussed.First,3-D double bounces modle about outdoor MIMO system with C xP (cross polarization) isgiven, and three performance indicators which includ average channel gain, average eigenchannelnumber and average capacity both under average power allocation and water-filling powerallocation are provided in the paper.Second, MIMO cube with12antennas is discussed. Expression about mutual impedancematrix is suggested using the mothod of induced electromotive force. Meanwhile, simulation of3-Ddouble bounces modle about outdoor MIMO system shows that under water-filling power allocation,the average eigenchannel number of MIMO cube demonstrates11, which has almost get to thenumber of i.i.d. Rayleigh-fading channel. The average capacity of MIMO cube withhalf-wavelength antennas is58.6bit/s/Hz with SNR20dB. Angle diversity is shown to improve thecapacity with antenna length below0.3wavelength. Above all, MIMO cube together with distantdiversity, polarization diversity and angle diversity can largely improve the capacity of the MIMOsystems.At last, a brand new MIMO octahedron is demonstrate. Expression about mutual impedancematrix of MIMO octahedron is provided to show its performance in outdoor environments. Underthe above model, MIMO octahedron can provide90%of the average capacity of MIMO cube witha size less than50%of MIMO cube.