Delay alignment modulation(DAM)is recently proposed as an effective technique to address the intersymbol interference(ISI)issue,which circumvents the conventional channel equalization and multi-carrier transmission.Mo...Delay alignment modulation(DAM)is recently proposed as an effective technique to address the intersymbol interference(ISI)issue,which circumvents the conventional channel equalization and multi-carrier transmission.Moreover,wireless communications are vulnerable to malicious eavesdropping and attacks due to their inherent open and broadcast nature.In particular,DAM not only eliminates the ISI at the desired receiver but may also introduce ISI to other locations,and thus is quite promising for secure communications.This paper considers the near-field secure wireless communication with DAM.To gain useful insights,it is first shown that when the antenna number of Alice is much larger than the number of multipaths for Bob and Eve,the delay compensation and low-complexity path-based maximal-ratio transmission(MRT)beamforming achieve a communication free of ISI and information leakage,owing to the asymptotically orthogonal property brought by the near-field nonuniform spherical wave(NUSW).The secrecy rate performance of path-based zero-forcing(ZF)beamforming toward ISI-free communication is then evaluated.Furthermore,the path-based optimized DAM beamforming scheme is proposed to maximize the secrecy rate,by considering the general case in the presence of some tolerable ISI.As a comparison,the benchmarking scheme of the artificial noise(AN)based orthogonal frequency-division multiplexing(OFDM)is considered.Simulation results show that DAM achieves a higher secrecy rate and lower peak-to-average-power ratio(PAPR)than the AN-based OFDM.展开更多
A simple scheme to generate optical quad- rature amplitude modulation （QAM） signals is proposed based on different types of delay interferometers （Dis）. The simulated results show that 16QAM, 64QAM and 256 QAM opt...A simple scheme to generate optical quad- rature amplitude modulation （QAM） signals is proposed based on different types of delay interferometers （Dis）. The simulated results show that 16QAM, 64QAM and 256 QAM optical signals can be generated by 2×2, 3 ×3 and 4×4 DI, respectively, and the outputs of the proposed scheme are similar to those of the conventional schemes. The operation principle is discussed and the transmission properties of the square 16QAM as well as 64QAM signals are analyzed and compared with common approach.展开更多
基金supported by the Natural Science Foundation for Distinguished Young Scholars of Jiangsu Province,China(No.BK20240070)the National Natural Science Foundation of China(No.62071114)the Fundamental Research Funds for the Central Universities(No.2242022k60004)。
文摘Delay alignment modulation(DAM)is recently proposed as an effective technique to address the intersymbol interference(ISI)issue,which circumvents the conventional channel equalization and multi-carrier transmission.Moreover,wireless communications are vulnerable to malicious eavesdropping and attacks due to their inherent open and broadcast nature.In particular,DAM not only eliminates the ISI at the desired receiver but may also introduce ISI to other locations,and thus is quite promising for secure communications.This paper considers the near-field secure wireless communication with DAM.To gain useful insights,it is first shown that when the antenna number of Alice is much larger than the number of multipaths for Bob and Eve,the delay compensation and low-complexity path-based maximal-ratio transmission(MRT)beamforming achieve a communication free of ISI and information leakage,owing to the asymptotically orthogonal property brought by the near-field nonuniform spherical wave(NUSW).The secrecy rate performance of path-based zero-forcing(ZF)beamforming toward ISI-free communication is then evaluated.Furthermore,the path-based optimized DAM beamforming scheme is proposed to maximize the secrecy rate,by considering the general case in the presence of some tolerable ISI.As a comparison,the benchmarking scheme of the artificial noise(AN)based orthogonal frequency-division multiplexing(OFDM)is considered.Simulation results show that DAM achieves a higher secrecy rate and lower peak-to-average-power ratio(PAPR)than the AN-based OFDM.
文摘A simple scheme to generate optical quad- rature amplitude modulation （QAM） signals is proposed based on different types of delay interferometers （Dis）. The simulated results show that 16QAM, 64QAM and 256 QAM optical signals can be generated by 2×2, 3 ×3 and 4×4 DI, respectively, and the outputs of the proposed scheme are similar to those of the conventional schemes. The operation principle is discussed and the transmission properties of the square 16QAM as well as 64QAM signals are analyzed and compared with common approach.
