Research On Time Delay Estimation Algorithm For Distributed MIMO Antenna Systems

Distributed multiple input multiple output(D-MIMO)is one of the key technologies in the fifth generation mobile communication(5G).It has advantages including high capacity,high spectrum utilization,low power consumption and better coverage,opening structure.Time delay estimation has always been one of the hotspots in communication research field,which directly determines the overall performance of D-MIMO antenna system.Signal detection,channel equalization,demodulation and other signal processing operations depend on the time delay estimation,which is closely related to the timing synchronization and channel estimation.The channel is usually multipath,and the current mainstream preamble-based frame synchronization method estimates the time delay of the first path which is the main path with minimum power constraint.And the position of the impulse response in the channel estimation is the estimated multipath relative time delay.Therefore,this paper will discuss the time delay estimation of distributed MIMO antenna system from the aspects of multipath time delay estimation and frame synchronization.Distributed Compressed Sensing(DCS)is an extension of Compressed Sensing.There are three joint sparse models and their reconstruction algorithms aiming at different joint sparsity of multiple signals.It can realize the joint reconstruction of multiple signals with less observations.DCS has been well applied in joint estimation of sparse channels in communication system and so on.ADMM(Alternating Direction Method of Multipliers)is a popular optimization method for distributed parallel computing,which can achieve the approximate optimal solution at each iteration and quick calculating speed.In the distributed MIMO system,the accuracy of multipath time delay estimation is not high,the computational complexity is large and the resolution is not enough.Combining the correlation and sparsity of multipath channel,this paper presents DCS time delay estimation method based on ADMM,which includes the establishment of estimation model,the determination of objective function and the solution of algorithm.Simulations show that the proposed method not only has better time delay estimation performance,but also improves the resolution,decreases the consumption of measurements and reduces the computational complexity.In the frame synchronization algorithm for estimating the first path arrival time delay of traditional D-MIMO antenna system,traversal search method is used to determine the correct synchronization index point,its computational complexity and the amount of calculation is large.The golden section method is an approximate optimal strategy to solve the one-dimensional minimization problem and it has the characteristics of low computational complexity.Considering the geometrical feature of synchronization metric function curves,a novel timing synchronization algorithm based on the golden section method is proposed to solve the high computational complexity of classical timing synchronization algorithms,and taking the frame synchronization and its application of distributed multiple input multiple output(MIMO)as example,the algorithm process and complexity analysis are given.The simulation experiments verified that the proposed method not only maintains the equivalent performance to the traditional algorithm,but also reducing the complexity greatly.