Distributed Mimo Signal Detection Technology

By combining the merits of MIMO and distributed antenna system, distributed MIMO is drawing intensive attention both from academic and industry. Distributed MIMO is promised as a key technology in future wireless communication systems due to its unique merits such as large system capacity, low transmit power, uniform and enhanced coverage and low radiation on the human body.In distributed MIMO systems, the antennas at the side of base station are not co-located in the base station, but distributed in different locations, making the distance from different base station antennas to the mobile station different. Hence, in the downlink of distributed MIMO systems, the transmit signals from different transmit antennas experience different channel propagation delays to arrive in the mobile station. Because of the asynchronous arrival of transmit signals in distributed MIMO systems, the detection algorithm in traditional MIMO systems can no longer be applied in distributed MIMO systems. Novel distributed MIMO detection scheme is needed to solve this problem.Aiming at resolving the asynchronous reception problem in the downlink of distributed MIMO systems, there exist some detection algorithms such as distributed space time codes and iterative trellis search detection. However, as in the area of distributed MIMO detection, distributed MIMO performance analysis and distributed MIMO channel estimation based on layered space time codes structure, there is limited research work. Hence, in this paper, we present some research wok in the three topics mentioned above:In the topic of distributed MIMO detection, we propose a coherent receiver model for distributed MIMO systems to solve the asynchronous reception problem in the downlink. Based on the proposed receiver model, transmit signals can be recovered from a single receive antenna; moreover, by adopting the coherent receiver model, some existing signal detection algorithms in traditional MIMO systems can be extended to distributed MIMO systems. In this paper, we emphasis on the distributed MIMO zero forcing detection, maximum likelihood detection and minimum mean square error detection. The simulation results are presented to compare the proposed distributed MIMO detection algorithms.In the topic of distributed MIMO performance analysis, we derive the mathematical expression for distributed MIMO BER performance by theoretical analysis. Base on the theoretical BER expression, we adopt a sequential quadratic programming method to investigate the optimum channel propagation delays in distributed MIMO systems. Moreover, we research the influence of the distributed MIMO system parameters on the BER performance by means of theoretical analysis and simulation. The results from theoretical analysis and simulation show that the BER curve from simulation results agrees well with the curve from theoretical analysis; in the 2×1 distributed MIMO system, BER first decreases and then improves with the increase of the channel propagation delays.