In this paper, the ship’s rotating propeller is a considered as rotating magnetic dipole. The shaft-rate magnetic field is modeled, and an inversion calculation is utilized to realize the magnetic target localization. The low frequency of the shaft-rate magnetic field provides long propagation distance, high stability, and low interference by sea conditions and other noises. The magnetic field signal has an important role in target and location detection. In the developed model, the magnetic moment of the rotating magnetic dipole is decomposed into three orthogonal magnetic moments indicated by mp, mf and ml. The mentioned moments can be obtained through a three-component integration of the measured magnetic field of the rotating dipole at a point. The relation between the eigenvectors of these orthogonal magnetic moments and the coordinates of the observation position is employed to obtain the coordinates and the magnetic target position. In the simulation, the relative and absolute errors of the location method are analyzed, while the measurement noise confines the positioning distance. Finally, the rotating magnetic field of 80 points is measured, and the feasibility of the rotating magnetic model is verified. Besides, the relative mean error of 80 points is equal to 3.7%, demonstrating the feasibility of the location method. However, due to some experiment limitations, including the measurement distance, measurement error, and the experimental equipment sensitivity, the maximum relative error is obtained as 7.4% which is higher than its theoretical value.

In this paper, we study data transmission in the Terrestrial–Satellite Integrated Network (TSIN), where terrestrial networks and satellites are combined together to provide seamless global network services for ground users. However, efficiency of the data transmission is limited by the time-varying inter-satellite link connection and intermittent terrestrial–satellite link connection. Therefore, we propose a link-state aware hybrid routing algorithm, which selects the integrated data transmission path adaptively in this paper. First of all, a space–time topology model is constructed to represent the dynamic link connections in TSIN. Thus, the transmission delay can be analyzed accordingly, and the data transmission problem can then be formulated. To balance the effectiveness and accuracy of searching a hybrid path, we carefully discuss the optimization of space–time topology updating, and propose an inter-satellite link selection algorithm. For the terrestrial–satellite link in hybrid routing, the data transmission problem is transformed into a weighted bipartite graph matching problem and solved with a Kuhn–Munkres-based link selection algorithm. To verify the effectiveness of our proposed routing algorithm, extensive simulations are conducted based on a realistic Hongyun constellation project. Results show that the network performance is improved with respect to data transmission delay, packet loss rate, and throughput.

In this Study, the application of wavelet threshold denoising in weak signal detection of underwater targets under complex sea conditions is discussed. Firstly, the basic principle and steps of wavelet threshold denoising method based on Mallat decomposition are analyzed. Then a new threshold function is proposed to overcome the shortcomings of traditional Donoho hard and soft thresholds. The denoising effects of wavelet and wavelet packet threshold denoising methods under hard threshold, soft threshold and new threshold functions are simulated, and the signal-to-noise ratio (SNR) and mean square error (MSE) after denoising are taken as evaluation indexes. The results show that the improved threshold denoising method outperforms the traditional threshold denoising methods.

Non-orthogonal multiple access (NOMA) has been extensively studied to improve the performance of the Terrestrial-Satellite Integrated Network (TSIN) on account of the shortage of frequency band resources. In this paper, the terrestrial network and satellite network synergistically provide complete coverage for ground users, and based on the architecture, we first formulate a constrained optimization problem to maximize the sum rate of the TSIN under the limited spectrum resources. As the terrestrial networks and the satellite network will cause interference to each other, we first investigate the capacity performance of the terrestrial networks and the satellite networks separately, in which the optimal power control factor expression is derived. Then, by constructing the relationship model between user elevation angle, beam angle and distance, we develop a dynamic group pairing schemes to ensure the effective pairing of NOMA users. Based on the user pairing, to obtain the optimal resource allocation, a joint optimization algorithm of power allocation, beam channel and base station channel resource is proposed. Finally, simulation results are provided to evaluate the user paring scheme as well as the total system performance, in comparison with the existing works.

In the article titled “The Precompression Processing of LMS Algorithm in Noise Elimination” [1], the corresponding author Professor Chunsheng Lin has been removed from the authors’ list where Professor Ning Zhang would be the corresponding author. The correct authors’ list is shown above.