Research On Space Time Coding Technology Based On USRP

Space-time coding technology,as a key technology of MIMO systems,combines channel coding,modulation,transmission and receive diversity to multiply the channel capacity and frequency band utilization of the system without adding additional bandwidth and transmit power.The software radio system based on USRP design has good openness and scalability,so it is widely used in the research of MIMO technology.Based on NI USRP-2920 and LabVIEW,this paper constructs SISO,SIMO and MIMO wireless communication simulation system,and uses this system to study space-time coding and channel estimation techniques.Based on software radio technology research,software basic transceiver module such as source coding,generation of data packets,baseband modulation,addition of training sequences,pulse shaping,USRP transmission and reception,extraction of information,matching filtering,synchronization,channel estimation,baseband demodulation,decoding of data packets,and restoration of pictures are realized by LabVIEW programming design.Based on the analysis of the configuration of USRP hardware,SISO,1×2 SIMO and 2×2 MIMO real-time data transmission and reception simulation systems were built using two,three and four sets of USRP hardware devices.The core software modules of MIMO systems such as space-time codec and channel estimation are implemented by using LabVIEW programming.Transceiver testing and bit error rate analysis for the simulation system.After the test signal is received and demodulated without distortion,real-time transmission and reception of text and picture files can be completed.In the error rate analysis,the transmission and reception constellation and bit error rate under different modulation and demodulation modes are tested firstly.It is tested that the bit error rate of the system is lower in the 8QAM modulation mode.Then test the bit error rate of SISO,SIMO and MIMO simulation system in8 QAM modulation and demodulation mode,and analyze the influence of different antennanumbers on the system bit error rate.After testing,the more the number of antennas,the lower the system error rate.