Research On Space Time Codes And Key Techniques For CPM-MIMO Systems

With the development of internet of things(IOT),wireless sensor networks(WSN)and mobile payment,wireless communications have played an irreplaceable role in people's daily life.The development of wireless communication in future will move toward high power efficiency,high spectrum efficiency,high capacity,high reliability,and low complexity.Continuous phase modulation(CPM),put forward in 70's last century,cherishes high power efficiency,high spectrum efficiency as compared with linear modulations(PSK,QAM).The initial research on CPM is confined to single-input single-output(SISO)systems.With the development of multi-input multi-output(MIMO)technology,until the beginning of this century,some scholars imitate the practice of linear modulations,and attempt to combine space-time coding(STC)with CPM-MIMO systems to further improve the capacity and anti-fading performance of CPM-MIMO system.Based on the existing research of scholars around the world,the CPM-MIMO system is deeply explored combined with space-time coding,antenna selection,network coding.Theoretical researches are carried out in terms of error performance,capacity,symbol data rate,diversity gain,antenna-selection gain and system complexity.Some academic achievements have been achieved as follow:(1)Research on the performances of CPM-MIMO systems including bit error rate,capacity and antenna selection:as for the bit error rate,CPM signal is decomposed into the superposition of multiple pulse amplitude waveforms(PAM),and the average bit error rate(BER)of CPM-MIMO system is derived.As for the capacity,the analysis is carried out from the perspective of symmetrical information rate(SIR),and the capacity with constrained spectrum under different CPM modulation parameters and modulation mechanism is discussed.As for the performance of antenna selection(AS)in CPM-MIMO system,several joint antenna selection algorithms are summarized and improved in terms of the cost and complexity of hardware resources.Simulations show that when the total number of antenna selections increases from 3 to 5,the performance improvement of both incremental JTRAS algorithm and decreasing JTRAS algorithm is about 1dB.Finally,a scheme of adaptive joint transmit and receive selection(Adaptive JTRAS)is proposed to find the tradeoff between system performance and computational complexity.(2)Research on the combination of STC and CPM-MIMO systems:First,an unusual STC,i.e.threaded space-time code(TSTC),is introduced and the transmission module of TSTC-CPM is designed.At receiver,a soft information demodulation is proposed for joint decoding.Moreover,the feasibility of the system is verified via simulation.Secondly,an idea of adaptive space-time code(ASTC)is proposed.A CPM-MIMO system based on ASTC is designed.Finally,it is found that the system can achieve the best trade-off between efficiency and reliability through the analysis and simulation in terms of symbol data rate and frame error rate.For example,in practical applications,the transmitter can adjust and select appropriate space-time codes as the transmission schemes in real time according to channel state information and users' requirements:when the channel conditions are good,the transmitter can adopt BLAST mechanism;when the channel conditions are bad and users communicate with voice or message,the transmitter can adopt Hybrid STC mechanism;when the channel conditions are bad and users communicate with image or video,the transmitter can adopt OSTBC mechanism.(3)Research on the antenna selection of the Alamouti mechanism in the CPM-MIMO system:On the basis of Lauren decomposition method and CPM signal difference matrix,the bounds of frame error rate for the antenna selection of Alamouti mechanism in CPM-MIMO systems are derived on the basis of sequential statistical theory.Experimental results show that the diversity gain of the system is 2dB when the number of transmitting antennas and receiving antennas are both two and there is no selection of transmitting antennas under the Alamouti mechanism.On the other hand,the diversity gain of the system is 3dB when we select two out of the three total antennas for transmission.This shows that diversity gain will be more obvious with the support of selective gain.(4)Research on the antenna selection of the network coding in the CPM-MIMO system:First,this paper proposes a system of TWRM-CPM.Secondly,at the receiver,we decrease the decoding complexity by simplifying the joint state trellis diagram.Finally,based on the maximum signal-to-noise ratio criterion,the performance of several antenna selections in TWRM-CPM system is simulated and compared.