Design And Research On Cooperative Scheme And Bit-to-Symbol Mapping For Cooperative Spatial Modulation System

By erecting multiple transceiver antennas,multiple-input multiple-output(MIMO)technology can obtain high throughput and spectrum efficiency without increasing bandwidth and transmission power.However,the performance of MIMO systems is limited by the inter-channel interference(ICI),inter-antenna synchronization(IAS),high complexity and so on.Cooperative communication technology,originated also from MIMO technology,makes use of the random distributed relay nodes to form a virtual MIMO system,which effectively improves the system performance,obtains the diversity gain,expands the transmission distance and covering area,and overcomes the channel fading problem.Spatial modulation(SM),as an extension of MIMO technology,is a new three dimension(3D)modulation technology by introducing antenna selection mechanism,which improves the transmission rate and system performance and solves the common problems in MIMO systems,by activating only one transmit antenna in one communication process.In this thesis,based on the bit-to-symbol mapping scheme for SM system,a joint bit-to-symbol mapping scheme and cooperative protocol for cooperative SM systems are proposed by extending the space dimension from transmit antenna to relay node and their combination,which brings into the advantages of SM technology and cooperative communication technology.The main research contents are as follows:Firstly,the bit-to-symbol mapping scheme for SM systems is studied.Considering the channel state information(CSI)at each transmit antenna,a realization process and simulation results of the channel gain based bit-to-symbol mapping scheme are shown.With the consideration of the channel correlation and there is no limit of the number of receive antenna,a cosine similarity based bit-to-symbol mapping scheme for SM system is proposed,where the detailed mapping procedure and the realization process are presented.Then,the simulation results and performance analysis show its superiority compared with the conventional mapping scheme and other mapping scheme.Secondly,an incremental hybrid decode-amplify-forward(IHDAF)protocol based cooperative SM system.is proposed,which selects direct transmission or the corresponding relaying protocol,such as decode-and-forward(DF)protocol or amplify-and-forward(AF)protocol,by comparing the instantaneous signal-to-noise ratio(SNR)of the direct link and the relay link to the corresponding SNR threshold,respectively.The signal processing algorithms and the system performance of outage probability have also been provided.Simulation results show the system outage probability of the cooperative SM system with IHDAF protocol outperforms the conventional cooperative SM systems with AF protocol and DF protocol.Furthermore,the influence of the relay location and power allocation factor on the outage probability performance has also been investigated for the IHDAF based cooperative SM system.Finally,a CSI based bit-to-symbol mapping scheme for multi-relay cooperative SM system is proposed,where the space dimension extends from transmit antenna to relay node and their combination.The bit-to-relay mapping scheme is firstly made sure with the consideration of the correlation among the channels from source to relay.By extracting the information of channel magnitude and phase at each transmit antenna,a joint selection scheme of relay node,transmit antenna and modulation symbol is proposed.Then the simulation results of the proposed mapping scheme under two different cooperative protocols are obtained.The system performance of bit error rate(BER)under different simulation parameters is compared.