Research On Several Modulation And Receiving Technologies In MIMO Wireless Communication

As an important part of modern wireless communication system,multi-input multi-output(MIMO)technology plays an important role in ensuring high-speed transmission and good signal detection quality.It can improve transmission efficiency and system capacity by utilizing the spatial freedom provided by multiple antennas at the transmitter and receiver.Spatial modulation system and spatial multiplexing system are two of classical MIMO systems,however,traditional spatial modulation technique has lower multiplexing gain although it avoids the inter-channel interference by only activating one transmitting antenna at every transmission time.Besides,the spatial multiplexing system achieves lower diversity gain at receiver although it has high multiplexing gain,which can't guarantee the detection quality of interfered signals produced by parallel transmission.Therefore,in this paper,we study the dual-polarization spatial modulation technology based on multiplexing design and the approximated lattice reduction algorithm which can improve the signal detection quality of simple detectors in spatial multiplexing system.Besides,the satellite communication also plays an important role in modern wireless communication system,and its bandwidth resources are also increasingly scarce,however,due to the limit of physical space on satellite,MIMO techniques on earth are not suitable for it,so we propose to apply orbital angular momentum(OAM)in the satellite communication to improve its transmission speed.Firstly,for a general investigation,we study the performance of dual-polarized spatial modulation(DPSM)system over Nakagami-m fading channel,which is a more general fading channel than Rayleigh and Rice channels.DPSM can improve the spectral efficiency and reduce the space occupancy by using the polarized antennas.We have derived a tight upper bound of average bit error rate(ABER)for DPSM scheme over Nakagami-m fading channel,and present detailed analysis of performance for different shape parameter m in the channel model.Secondly,the performance of approximated lattice reduction algorithm in spatial multiplexing system is analyzed.It is proved that the approximated basis vector reordering criterion(ABVR)aided ZF and SIC detection can achieve full receiving diversity through a new theoretical derivation,and in this way,a tighter upper bound of the average symbol error probability is demonstrated.Besides,The simulation results also show hat,compared with the original CLLL and CLLL-Siegel algorithms,DLLL-ABVR maintains similar detection perfomance and converges much faster with much lower computational complexity.Finally,the modulation technique of satellite communication is studied.We propose to apply OAM in the modulation of satellite communication,and consequently,an extra OAM freedom degree is used to improve the spectral efficiency of satellite communication.Besides,the antenna array in corresponding modes at the receiver can also increase the accuracy of signal detection.