Research On Signal Detection Algorithm In Generalized Spatial Modulation System

As an extension of spatial modulation(SM)technology,generalized spatial modulation(GSM)technology activates multiple antennas to transmit datas at the same time,thus a combination of spatial multiplexing technology and SM technology is realized effectively.At the same time,GSM technology overcomes the serious waste of space resources with the increase of the number of transmitting antennas and the constraint that the number of transimit antennas has to be the integer power of two in SM technology.Compared with SM system,GSM system can achieve a good compromise between spectrum efficiency and design cost.Therefore,GSM technology has become one of the most competitive candidate technologies for the fifth generation(5G)mobile communication systems.In the GSM system,when the full-search Maximum Likelihood(ML)algorithm is used for signal detection,although the optimal detection performance can be obtained,it has extremely high complexity and is therefore difficult to apply in practical engineering.Compared with ML detection algorithm,the traditional linear detection algorithm has a lower complexity,but its detection performance has a significant loss.Therefore,the signal detection algorithm of GSM system was studied in the thesis,and the main contents and innovative ideas are as follows:1.The basic principle and system model of SM technology and GSM technology are emphatically introduced.Based on this,ML detection algorithm,linear detection algorithm and lattice reduction aided linear detection algorithm in GSM system are analyzed in detail.These algorithms are simulated and comparied as well.2.In GSM system,the traditional QR-Decomposition with M-algorithm(QRD-M)retains the fixed number of nodes in each layer,which will lead to additional computation.To solve this problem,a QRD-M detection algorithm based on dynamic M-value is proposed.The algorithm use the designed threshold to compare with the cumulative branch metrics,and the number of nodes is dynamically retained in each layer to reduce the number of search branches.Simulation results show that QRD-M detection algorithm based on dynamic M-value can effectively reduce the complexity at the cost of a small amount of performance loss compared with traditional QRD-M detection algorithm.3.Aiming at the problem of noise influence in the search paths of traditional QRD-M detection algorithm and the QRD-M detection algorithm based on dynamic M value,a QRD-M detection algorithm based on pseudo-inverse minimum mean square error(MMSE)is further proposed.This algorithm constructs a new channel matrix and receiving signals by utilizing MMSE filtering principle,and then uses QRD-M algorithm to detect signal.Simulation results show that under the same conditions,the traditional QRD-M detection algorithm based on pseudo-inverse MMSE can achieve almost the same performance as the traditional QRD-M detection algorithm when retaining half of the search branches.In the case of QPSK modulation with 4 transmitting antennas and 4 receiving antennas,and the number of active antennas is 2 or 3,when the traditional QRD-M detection algorithm retains 4 branches,the QRD-M detection algorithm of dynamic M value based on pseudo-inverse MMSE not only improves the detection performance,but also reduces the complexity slightly compared with the traditional QRD-M detection algorithm.4.For the underdetermined system,the GSM signal detection algorithm based on traditional generalized orthogonal matching pursuit(GOMP)has the problems of low probability of selecting the correct active antenna index and high complexity.To solve these problems,the GSM signal detection algorithm of GOMP based on Dice coefficient criterion and the GSM signal detection algorithm of GOMP based on threshold judgment are proposed respectively.The GSM signal detection algorithm of GOMP based on Dice coefficient criterion replaces the inner product method used in calculating the channel matrix and the current residual with the Dice coefficient criterion,so the better subchannel is highlighted to improve the accuracy of legal activating the antenna index selection.For the GSM signal detection algorithm of GOMP based on threshold judgment,this algorithm adaptively selects the candidate active antenna index by introducing a threshold using Dice coefficient,and combines with the MMSE algorithm,and adds the reliability judge rule(RJR)to reduce the number of searches.Simulation results show that compared with the GSM signal detection algorithm based on traditional GOMP,the GSM signal detection algorithm of GOMP based on Dice coefficient criterion greatly improves detection performance with only a small increase in its complexity.The GSM signal detection algorithm of GOMP based on threshold judgment effectively reduces the complexity at the cost of a small amount of performance loss,and a better compromise between detection and complexity is achieved compared with the GSM signal detection algorithm based on traditional GOMP.At the same time,with the increasing of active antennas,the complexity is reduced to a greater extent.