Research On Application Of Troposcatter Adaptive Modulation And Coding Based On 5G LDPC Code

At present,with the progress of 5G communication technology and the requirement of tropospheric scattering communication system for communication rate,system capacity and anti-interference ability,it is a trend to combine 5G technology with tropospheric scattering communication.According to different channel conditions,AMC technology can select different MCS,including channel encoding/decoding and modulation/demodulation methods in real time.It is an effective way to enhance transmission speed and systerm capacity in scattering communication,which can improve the utilization of channel spectrum resources.The HARQ can improve system’s BER,which is a means to improve anti-interference ability.The LDPC code used in 5G standard has the characteristics of using multiple code rates and lengths,and it fits the application of AMC technology such as rate compatibility,adaptive variable speed transmission,etc.In addition,the structure of LDPC supports the application of HARQ technology.The combination of 5GLDPC code with AMC and HARQ technology is very suitable for the current development trend of scattering communication.In this paper,5G NR-LDPC code is applied in scattering communication system.Moreover,this paper proposes a decoding algorithm for scattering communication environment,and gives adaptive coding and modulation schemes based on different hierarchical orders and determines the switching threshold criterion of AMC.Firstly,the basic concepts of scattering channel and 5G NR-LDPC code are described.For tropospheric scattering channel,the principle and key technologies are mainly studied.For 5G NR-LDPC code,the encoding and decoding principles of LDPC code are mainly studied,and the BER performance of three decoding methods is compared.Then,the scattering communication model is established according to the characteristics of tropospheric scattering communication and the normalized minimum layered decoding algorithm is improved.The principle of AMC based on channel condition is analayed,and the AMC in scattering communication system based on channel state information is established,and the AMC threshold selection algorithm based on different diversity order is designed The BER performance and throughput of different schemes are obtained.Finally,the characteristics of the three HARQ transmission mechanisms are described,and the BER performance and throughput performance of the three transmission mechanisms are compared to determine the optimal transmission mechanism.In this paper,the AMC scattering communication system based on HARQ retransmission mechanism is established.And the performance between the new scheme and traditional scheme are compared through simulation.The results show that the new scheme can improve the throughput significantly while remain the BER performance unchanged...