Capacity Enhancement Technology Based On The Spatial Location Point

Physical Layer Security(PLS)communication technology aims to reduce the reliance on secret keys in traditional secure communication by leveraging the inherent characteristics of the physical layer.However,current PLS communication is limited to angle domain security communication system design,and distance-related Frequency Diverse Array(FDA)still has defects such as time dependence.Thesis presents a new PLS communication design solution,Distance-Dependent Secure Communication Method(DDSCM),which not only improves security capacity but also enhances system concealment performance shown by experimental results.The DDSCM technique combined with Time Reversal(TR)technology results in a distance-related system,TRDDSCM.Compared with the PEQ-DDSCM system obtained by combining with preequalization technology,the TR-DDSCM system can more effectively utilize the energy of the multipath channel,resulting in further improvements in legitimate receiver Signalto-Interference plus Noise Ratio(SINR),system security capacity,and concealment performance.Thesis conducts simulation studies on PLS Communication and Covert Communication aspects based on a Single-Carrier Frequency Domain Equalization(SCFDE)broadband system.The current status and key technologies of PLS Communication and Covert Communication are investigated,including signal processing methods,important parameter impacts,and system design.DDSCM technology is utilized to design a position-related secure communication system to compensate for the current deficiencies in secure communication.The influence of each parameter in the DDSCM system on system security performance is analyzed from the perspectives of security reception range and secrecy capacity.Combining with simulation results,the advantages of PEQ-DDSCM system and TRDDSCM system are analyzed and compared with traditional pre-equalization system and TR system,both of which can quickly reduce the channel capacity of eavesdropping parties over short distances.Additionally,the TR-DDSCM system uses TR’s spatiotemporal focusing and sub-channels in DDSCM to decrease the frequency selectivity of the legitimate channel,thereby reducing Inter-Symbol Interference(ISI)and increasing legitimate channel capacity.Thus,the security capacity of the entire system is improved from the perspectives of reducing the eavesdropper’s channel capacity and increasing the legitimate channel capacity.Moreover,a minimum channel usage algorithm is proposed to find the number of channels required to transmit a given amount of information under certain covertness constraints.Simulation results can directly observe the impact of covertness constraints on system throughput.This method is applied to AWGN channels and Rayleigh channels and combined with the relative distance between the eavesdropper and the legitimate receiver,and the simulation results show that the minimum channel usage number decreases and the system throughput increases as the relative distance increases under certain constraints.The study also found that applying PLS technology,such as TR-DDSCM,in covert communication can also achieve better concealment performance.