Research On Low-complexity Signal Detection Algorithm Based On Quadrature Spatial Modulation

With the popularity of smart mobile devices and the emergence of high-definition digital services such as 4K and VR video,rate,reliability,spectrum efficiency and energy efficiency of mobile communications are increasingly demanded.A multi-antenna transmission technology represented by a conventional MIMO system can achieve high spectral efficiency,high transmission,and high reliability.However,increasing the transmission rate simply will inevitably increase energy consumption and complexity,which will violate the concept of green communication.To solve this problem,a new multi-antenna transmission technology is proposed: Spatial Modulation(SM)technology.SM can solve the problem of traditional MIMO,but the spectrum efficiency of the system is low.The Quadrature Spatial Modulation(QSM)technology is an improved spatial modulation scheme,which inherits the advantages of the spatial modulation system and further improves the spectrum efficiency of the system.Compared with traditional MIMO technology,QSM finds a balance between spectrum efficiency and energy efficiency,which can meet people's increasing requirements of wireless communications while reducing energy consumption.And QSM can solve the problem of serious inter-channel interference in traditional MIMO,and has the advantage of low complexity of the design of the transceiver.This makes it possible for QSM to become a hot technology for future wireless communications.Based on the MIMO system,this thesis aims to achieve better multi-antenna transmission,mainly studies SM receiver detector,two low-complexity signal detection algorithms are proposed.Such as:1.According to the existing EMF algorithm in orthogonal space modulation system,a low complexity improved EMF algorithm is proposed.The QSM system sends the real and imaginary parts of a modulation symbol separately,which leads to the decision vector in the EMF algorithm are orthogonal to each other in the first n columns and the rear n columns in the sparse reconstructed system.In view of this property,the algorithm estimates the real part and imaginary part of the modulation symbol separately,which greatly reduces the complexity of signal detection.2.Aiming at the problem that the complexity of QSM is still high,while equipped with a large-scale antenna or the high-order modulation.A detection algorithm for narrowing the search space of the transmitting antenna is proposed.The algorithm performs multiple iterations by linear detection algorithm according to the rules of the Orthogonal Matching Pursuit algorithm to select the first n active antennas with the highest probability as the candidate set,and then uses the optimal detection algorithm to accurately estimate the candidate set.This algorithm further reduces the system complexity by narrowing the search space of the transmitting antenna,and is insensitive to the number of transmitting antennas,which is beneficial to practical applications.