Distributed Mimo Transmission Antenna Location Optimization Techniques

By combining the advantages of Multiple-Input Multiple-Output (MIMO) technology and distributed antenna system, distributed MIMO has attracted great interests both in academia and industry due to its large system capacity and low transmit power. Distributed MIMO has become research hotspot.In distributed MIMO systems, the location of transmit antennas will impact the system performance. However, the existing study of antenna location optimization technology mainly concentrated on the traditional cellular mobile communications network and some special scenarios. There are few studies on the distributed MIMO transmit antenna location optimization problem. Therefore, we begin our study in order to solve this problem.For distributed transmit antenna Vertical Bell Laboratories LAyered Space-Time (V-BLAST) system, the area averaged bit error ratio (AABER) of V-BLAST with two distributed transmit antennas in a linear cell is studied, considering the effects of channel propagation delay, path loss, shadow fading, multipath fading and white Gaussian noise. Theoretical analyses show that the antennas should be located symmetrically about the cell center in order to achieve the best AABER. Numerical calculation and simulation results show that the optimal antenna location is 105m and 195m when the cell length is 300m.For distributed transmit antenna Orthogonal Space-Time Block Coded (OSTBC) system, the symbol error ratio (SER) of OSTBC with distributed transmit antennas is studied, considering the effects of path loss, correlated shadow fading, multipath fading and white Gaussian noise. Theoretical and numerical results show that the SER depends on the cross-correlation coefficient and the standard deviation of shadow fading. Then, we derive the area averaged symbol error rate (AASER) in a linear and a circular cell based on SER, respectively. The optimal transmit antenna location is obtained by minimizing AASER. For a linear cell, when the number of transmit antennas is odd, the optimal transmit antenna location is that one should be placed in the center of the linear cell and the remaining should be symmetrical with respect to the linear cell center; when the number of transmit antennas is even, the optimal transmit antenna location should be symmetrical with respect to the linear cell center.For a circular cell, we get the the following optimal design of antenna location: (1) the optimal antenna location should be symmetrical with respect to the circular cell center; (2) the optimal antenna location depends on the standard deviation of shadow fading (the distance from the transmit antenna to the cell center increases as the shadow fading standard deviation increases); (3) the optimal antenna location is related to the number of the transmit antennas (the distance from the transmit antenna to the cell center increases with the increase of the number of the transmit antennas).The research results of distributed MIMO transmit antenna location optimization in this paper provide a viable design scheme for the next generation distributed antenna systems based mobile communication networks, digital TV/Radio wireless communication networks from the perspective of the system BER(Bit Error Rate), which are of great theoretical and economic value.