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Article List
2026, 24(3):275-280.
DOI: 10.11805/TKYDA2025094
Abstract:
With the rapid growth of satellite communication demands, the scarcity of spectrum resources has become increasingly prominent. To ensure full utilization of system bandwidth and reduce the performance gap between adjacent 22n-order Quadrature Amplitude Modulation(QAM) superposition schemes, this paper investigates the application of a 22n+1-order-based superposed 32QAM scheme in Non-Orthogonal Multiple Access(NOMA) satellite networks. First, a 32QAM constellation formed by superposing a novel 8QAM and Quadrature Phase Shift Keying(QPSK) is designed, and joint encoding is employed between two users to achieve rotation of the 8QAM signal. Then, to obtain the optimal superposed constellation with the objective of maximizing Constellation-Constrained(CC) capacity, the optimal power allocation algorithm is simplified under high Signal-to-Noise Ratio(SNR) conditions. Simulation results demonstrate that when Mutual Information(MI) exceeds 4.98, the proposed scheme achieves a 0.29 wider range of power coefficient ratios compared to the square 8QAM+QPSK scheme, and its Bit Error Rate(BER) performance outperforms the other three schemes(square 8QAM+QPSK, conventional 8QAM+QPSK, and superposed 32PSK).
With the rapid growth of satellite communication demands, the scarcity of spectrum resources has become increasingly prominent. To ensure full utilization of system bandwidth and reduce the performance gap between adjacent 22n-order Quadrature Amplitude Modulation(QAM) superposition schemes, this paper investigates the application of a 22n+1-order-based superposed 32QAM scheme in Non-Orthogonal Multiple Access(NOMA) satellite networks. First, a 32QAM constellation formed by superposing a novel 8QAM and Quadrature Phase Shift Keying(QPSK) is designed, and joint encoding is employed between two users to achieve rotation of the 8QAM signal. Then, to obtain the optimal superposed constellation with the objective of maximizing Constellation-Constrained(CC) capacity, the optimal power allocation algorithm is simplified under high Signal-to-Noise Ratio(SNR) conditions. Simulation results demonstrate that when Mutual Information(MI) exceeds 4.98, the proposed scheme achieves a 0.29 wider range of power coefficient ratios compared to the square 8QAM+QPSK scheme, and its Bit Error Rate(BER) performance outperforms the other three schemes(square 8QAM+QPSK, conventional 8QAM+QPSK, and superposed 32PSK).
2026, 24(3):299-313.
DOI: 10.11805/TKYDA2025233
Abstract:
To address the limited transmission capability of power grid monitoring information in remote and disaster?affected areas, this paper proposes a Low Earth Orbit(LEO) satellite?based Internet of Things(IoT) transmission scheme tailored for emergency power grid monitoring applications. Firstly, a multi?level priority scheduling mechanism is developed by incorporating key transmission parameters such as the number of retransmissions and backoff time, thereby ensuring the accuracy and timeliness of information delivery according to different emergency levels. Secondly, in consideration of the highly dynamic characteristics of satellite/Unmanned Aerial Vehicle(UAV) communication channels, a closed?loop demodulation method is proposed to mitigate the impact of time?varying Doppler shifts. This method extracts dynamic Doppler frequency offset information by analyzing the relationship between the main and side peaks in Fast Fourier Transform(FFT)?based demodulation decisions, and introduces a feedback loop to dynamically compensate for the frequency offset in subsequent symbol demodulation. This significantly enhances the Bit Error Rate(BER) performance of IoT transmissions under high?mobility channel conditions. Finally, to validate the effectiveness of the proposed method, a comprehensive performance evaluation is conducted through Matlab simulations and Field?Programmable Gate Array(FPGA)?based hardware testing. Both simulation and FPGA results demonstrate that the proposed closed?loop demodulation scheme achieves a markedly better BER performance than the traditional method. At a BER of 10?3, it provides an Signal-to-Noise Ratio(SNR) gain of about 2 dB at Spreading Factor(SF)=9, and the BER curve no longer shows a flooring effect as the SNR further increases.
To address the limited transmission capability of power grid monitoring information in remote and disaster?affected areas, this paper proposes a Low Earth Orbit(LEO) satellite?based Internet of Things(IoT) transmission scheme tailored for emergency power grid monitoring applications. Firstly, a multi?level priority scheduling mechanism is developed by incorporating key transmission parameters such as the number of retransmissions and backoff time, thereby ensuring the accuracy and timeliness of information delivery according to different emergency levels. Secondly, in consideration of the highly dynamic characteristics of satellite/Unmanned Aerial Vehicle(UAV) communication channels, a closed?loop demodulation method is proposed to mitigate the impact of time?varying Doppler shifts. This method extracts dynamic Doppler frequency offset information by analyzing the relationship between the main and side peaks in Fast Fourier Transform(FFT)?based demodulation decisions, and introduces a feedback loop to dynamically compensate for the frequency offset in subsequent symbol demodulation. This significantly enhances the Bit Error Rate(BER) performance of IoT transmissions under high?mobility channel conditions. Finally, to validate the effectiveness of the proposed method, a comprehensive performance evaluation is conducted through Matlab simulations and Field?Programmable Gate Array(FPGA)?based hardware testing. Both simulation and FPGA results demonstrate that the proposed closed?loop demodulation scheme achieves a markedly better BER performance than the traditional method. At a BER of 10?3, it provides an Signal-to-Noise Ratio(SNR) gain of about 2 dB at Spreading Factor(SF)=9, and the BER curve no longer shows a flooring effect as the SNR further increases.
2026, 24(3):265-274.
DOI: 10.11805/TKYDA2025080
Abstract:
As a crucial component of modern communication networks and an important domain of international competition, satellite communication faces increasingly severe interference threats, with its security and reliability encountering serious challenges. Against this backdrop, interference awareness technology has become a critical means of ensuring communication reliability, holding significant practical importance and promising application prospects. This paper first conducts a comprehensive analysis of several types of satellite communication interference signals. On this basis, the current research status of interference awareness technologies for satellite communication is investigated from three perspectives: interference detection, identification, and localization, along with the advantages and limitations of various technologies in the current interference environment. Finally, a brief outlook on the future development directions of interference awareness technology is provided.
As a crucial component of modern communication networks and an important domain of international competition, satellite communication faces increasingly severe interference threats, with its security and reliability encountering serious challenges. Against this backdrop, interference awareness technology has become a critical means of ensuring communication reliability, holding significant practical importance and promising application prospects. This paper first conducts a comprehensive analysis of several types of satellite communication interference signals. On this basis, the current research status of interference awareness technologies for satellite communication is investigated from three perspectives: interference detection, identification, and localization, along with the advantages and limitations of various technologies in the current interference environment. Finally, a brief outlook on the future development directions of interference awareness technology is provided.
4 Research on low-complexity coded-assisted carrier synchronization based on Newton‒Raphson algorithm
2026, 24(3):314-323.
DOI: 10.11805/TKYDA2025200
Abstract:
Coded-aided carrier synchronization can fully utilize the soft information of data symbols from the decoding process for carrier parameter estimation, demonstrating excellent performance under low Signal-to-Noise Ratio(SNR) conditions. Classical coded-aided carrier synchronization methods mainly solve nonlinear equations containing hidden variables through the Expectation-Maximization (EM) algorithm or its series expansion approximations, but suffer from high complexity or limited estimation accuracy. This paper exploits the characteristic that the Jacobian matrix of the log-likelihood function derivative in polar form is easy to derive, and uses the Newton-Raphson iterative algorithm to solve the nonlinear function. Under the condition of maintaining parameter estimation performance without degradation, the computational complexity of coded-aided carrier synchronization parameter estimation is significantly reduced. Computer simulations show that the proposed algorithm can achieve Bit Error Rate(BER) performance comparable to the EM algorithm while significantly reducing computational complexity, approaching that of series expansion approximation algorithms. It is applicable to single carrier linear modulation systems such as Binary Phase Shift Keying(BPSK), Quadrature Phase Shift Keying(QPSK), and Quadrature Amplitude Modulation(QAM).
Coded-aided carrier synchronization can fully utilize the soft information of data symbols from the decoding process for carrier parameter estimation, demonstrating excellent performance under low Signal-to-Noise Ratio(SNR) conditions. Classical coded-aided carrier synchronization methods mainly solve nonlinear equations containing hidden variables through the Expectation-Maximization (EM) algorithm or its series expansion approximations, but suffer from high complexity or limited estimation accuracy. This paper exploits the characteristic that the Jacobian matrix of the log-likelihood function derivative in polar form is easy to derive, and uses the Newton-Raphson iterative algorithm to solve the nonlinear function. Under the condition of maintaining parameter estimation performance without degradation, the computational complexity of coded-aided carrier synchronization parameter estimation is significantly reduced. Computer simulations show that the proposed algorithm can achieve Bit Error Rate(BER) performance comparable to the EM algorithm while significantly reducing computational complexity, approaching that of series expansion approximation algorithms. It is applicable to single carrier linear modulation systems such as Binary Phase Shift Keying(BPSK), Quadrature Phase Shift Keying(QPSK), and Quadrature Amplitude Modulation(QAM).
2026, 24(3):289-298.
DOI: 10.11805/TKYDA2025087
Abstract:
With the increasing demand for high spectral efficiency(>10 bps/Hz) and ultra?reliability (BER(Bit Error Rate)<10??) in 6G communications, this paper proposes a joint Orthogonal Time Frequency Space(OTFS) waveform design for terahertz(THz)?based Low?Earth Orbit(LEO) satellite communications. Aiming at challenges including 1.2 MHz Doppler shifts,120 μs delay spreads, and power amplifier nonlinearity(requiring PAR(Peak?to?Average Ratio)<4 dB) in satellite-terrestrial links, a Fractional Fourier Transform(FrFT)?based super?resolution channel estimation(error≤3 kHz) is developed,an Intelligent Reflecting Surface(IRS)?assisted 3D spatio-temporal-frequency beamforming architecture with 256 elements is established, and a Riemannian manifold?constrained constant envelope precoding algorithm is designed. Simulation results demonstrate that at 0.3 THz with 7 km/s relative velocity, the system achieves a BER of 1×10-7, a PAR of 3.5 dB, and a spectral efficiency of 12.4 bps/Hz(40% improvement over Orthogonal Frequency Division Multiplexing(OFDM)), while boosting power amplifier efficiency from 12.7% to 78.4%. Validated by 3rd Generation Partnership Project(3GPP) Non-Terrestrial Network(NTN) channel models, this scheme provides a highly robust and power-efficient waveform solution for 6G space-terrestrial integrated communications.
With the increasing demand for high spectral efficiency(>10 bps/Hz) and ultra?reliability (BER(Bit Error Rate)<10??) in 6G communications, this paper proposes a joint Orthogonal Time Frequency Space(OTFS) waveform design for terahertz(THz)?based Low?Earth Orbit(LEO) satellite communications. Aiming at challenges including 1.2 MHz Doppler shifts,120 μs delay spreads, and power amplifier nonlinearity(requiring PAR(Peak?to?Average Ratio)<4 dB) in satellite-terrestrial links, a Fractional Fourier Transform(FrFT)?based super?resolution channel estimation(error≤3 kHz) is developed,an Intelligent Reflecting Surface(IRS)?assisted 3D spatio-temporal-frequency beamforming architecture with 256 elements is established, and a Riemannian manifold?constrained constant envelope precoding algorithm is designed. Simulation results demonstrate that at 0.3 THz with 7 km/s relative velocity, the system achieves a BER of 1×10-7, a PAR of 3.5 dB, and a spectral efficiency of 12.4 bps/Hz(40% improvement over Orthogonal Frequency Division Multiplexing(OFDM)), while boosting power amplifier efficiency from 12.7% to 78.4%. Validated by 3rd Generation Partnership Project(3GPP) Non-Terrestrial Network(NTN) channel models, this scheme provides a highly robust and power-efficient waveform solution for 6G space-terrestrial integrated communications.
2026, 24(3):281-288.
DOI: 10.11805/TKYDA2025254
Abstract:
Routing methods in mega-constellation networks are critical and challenging for network performance. Dynamic topology changes incur a large amount of state interaction and routing update overhead, and require more routing convergence time. In this paper, from the perspective of complex network theory, we propose a pinning control-based routing method applicable to mega-constellation networks, where a small number of key nodes are selected based on the Maximum Local Traffic(MLT) in a distributed control framework for mega-constellation networks, and scalable routing is realized by controlling the states of these nodes. Simulation results demonstrate that the proposed routing selection method achieves performance comparable to or surpassing existing routing methods while reducing routing information exchange overhead. This validates its effectiveness as a novel routing control paradigm.
Routing methods in mega-constellation networks are critical and challenging for network performance. Dynamic topology changes incur a large amount of state interaction and routing update overhead, and require more routing convergence time. In this paper, from the perspective of complex network theory, we propose a pinning control-based routing method applicable to mega-constellation networks, where a small number of key nodes are selected based on the Maximum Local Traffic(MLT) in a distributed control framework for mega-constellation networks, and scalable routing is realized by controlling the states of these nodes. Simulation results demonstrate that the proposed routing selection method achieves performance comparable to or surpassing existing routing methods while reducing routing information exchange overhead. This validates its effectiveness as a novel routing control paradigm.
