With the increasing deployment of large low Earth orbit (LEO) satellite constellations, inter-satellite laser (ISL) communication has emerged as a key technology to enhance satellite network efficiency. However, the traditional process for establishing ISL links on-orbit involves significant manual adjustments, resulting in inefficiencies. This paper proposes a digital twin technology for an inter-satellite laser communication tracking system that utilizes digitally-driven stepping motors for enhanced precision and efficiency in laser link establishment. Simscape is used to create an integrated model, combining acquisition control programs, drive circuits, and stepping motors, enabling accurate simulation of dynamic system behavior. This method accurately simulates the dynamic performance of the tracking system, offering valuable simulation support for efficient laser link establishment in orbit, improving test efficiency, and accelerating the deployment of LEO constellations.

This article presents a TIADC model based on Verilog-AMS with the sub-ADC adopting pipeline ADC. The TIADC has 8 channels with a single-channel sampling rate of 1GS/s and a total sampling rate of 8GS/s with 12-bit resolution. It also completed the calibration of the offset mismatch, gain mismatch and timing skew. The paper uses iterative averaging algorithm for offset and gain calibration. With 2us calibration SNDR and SFDR can be improved by more than 20dB.

To meet the demand for high-performance clocks for 5G communications, this paper proposes a fast-locked 3–6 GHz ADPLL loop model based on the charge-steering-sampling (CSS) phase detection (PD) technique, which has an equivalent time-conversion resolution of 350 fs/bit and effectively reduces the quantization noise induced by the TDC. In addition, a two-stage Automatic Frequency Calibration (AFC) module is proposed to preset the frequency control words of the DCO coarse and medium tuning for fast locking. Further, a step-size controllable up/down counting filter is proposed to accelerate the locking speed and improve the frequency accuracy after locking. Based on TSMC 28nm technology, the overall ADPLL model is built using VerilogA/Verilog with a locking time of less than 1.8us, and the DCO part is implemented with a practical LC DCO structure, and achieves -122dBc/Hz@1MHz phase noise at an output frequency of 4GHz, which meets the requirement of fast locking under low phase noise.

Low Earth Orbit (LEO) satellites enable various Internet of Things (IoT) applications by providing plentiful observation data at different spatial scales. However, transmitting such a large volume of observation data to the ground for model training is challenging due to the intermittent connection between satellites and ground stations, leading to long training delays for task-oriented artificial intelligence models. Orbital federated learning has been investigated to enable on-board model training sharing model parameters instead of observation data, thus greatly reducing the communication overhead. However, these works underutilize the availability of inter-satellite links and ignore energy consumption. To fill this gap, we propose an energy-efficient federated learning scheme for earth observation applications in LEO satellite systems to minimize learning loss and energy consumption. Specifically, to reduce the effect of data heterogeneity on learning accuracy, we propose a satellite grouping scheme based on satellites' data distribution and communication delay to ground stations. Then, we optimize each satellite's transmission power and computing frequency under the constraint of training time. Experimental results based on popular datasets show the efficacy of the proposed scheme compared to benchmark methods.

With the advancements of software defined network (SDN) and network function virtualization (NFV), service function chain (SFC) placement becomes a crucial enabler for flexible resource scheduling in low earth orbit (LEO) satellite networks. While due to the scarcity of bandwidth resources and dynamic topology of LEO satellites, the static SFC placement schemes may cause performance degradation, resource waste and even service failure. In this paper, we consider migration and establish an online migration model, especially considering the dynamic topology. Given the scarcity of bandwidth resources, the model aims to maximize the total number of accepted SFCs while incurring as little bandwidth cost of SFC transmission and migration as possible. Due to its NP-hardness, we propose a heuristic minimized dynamic SFC migration (MDSM) algorithm that only triggers the migration procedure when new SFCs are rejected. Simulation results demonstrate that MDSM achieves a performance close to the upper bound with lower complexity.

The transmission mode of coaxial waveguide is TEM mode, based on the transmission characteristic, a dual-polarization waveguide antenna with high radiation efficiency and good cross polarization characteristics is presented. The waveguide antenna adopts the structure form of rectangular coaxial waveguide, its cutoff frequency is equal to zeros, by means of taking advantage of the transmission characteristic of the coaxial waveguide, this article reduces the cross section size and achieves the miniaturization,lightweight design. Compared with conventional waveguide antenna, the results show that the rectangular coaxial dual-polarization waveguide antenna has the characteristics of high polarization purity and high radiation efficiency; at the same time, its weight is reduced by more than 30% and its profile is reduced by more than 40%, providing new ideas for the miniaturization and lightweight design of waveguide antennas, possessing certain engineering application value.

The development of 6G communication has made low earth orbit (LEO) satellite networks to be a critical component of global communication systems. The high density of LEO satellites enables mobile devices to have continuous communication. However, managing satellites in mega-constellation LEO satellite networks poses a scalability challenge due to the large number of LEO satellite nodes. Besides, due to the high mobility of LEO satellites, inter-satellite handover frequently occurs, which leads to the degradation of traffic QoS (Quality of Service). To address these issues, in this paper, we propose a novel virtual node-based multi-controller management architecture for LEO-satellite constellation networks, that can effectively shield the dynamics of satellite network topology. In specific, we first redefine the virtual node as a geographical area with clear boundaries. Then, we set up domain controllers in each virtual node to manage the satellites. Besides, we propose a handover algorithm to reduce delay jitter and delay by jointly considering the probability of handover and the cost of rerouting. We conduct simulations on Starlink Phase I and the results show that compared with benchmark algorithms, the proposed architecture can reduce the delay jitter by more than 50% and the delay by 10%.

Three non-parameter nonlinear detectors are proposed in multi-band milimeter wave radio-over-fiber(mmw RoF) system to achieve the suppression of system damages. First, we introduce the theory of the three detectors. Without requiring the prior estimation of the system link, the detectors can learn and capture the link characteristics from only a few training data. The experimental investigations are conducted to verify the feasibility of the proposed methods and compare the suitability of different methods.

Recently with the massive explosion of remote sensing observation satellites and the deployment of low earth orbit (LEO) broadband communication satellites, the demand for data transmission of data relay satellites has increased sharply. Higher and higher capabilities have been proposed for data relay satellites. However, the current situation is the limited on-board storage capacity, the low microwave link rate. In view of the huge amount of data produced by various medium and low orbit vehicles, a satellite-to-ground laser communication application system is constructed based on the analysis of domestic and foreign relay satellite systems. The overall business process is also researched of this laser communication application system, from customer satellite resource application, link control to data return. Then the subsequent work is prospected.

With the further reduction in cost and the increase in bandwidth, as well as the increase in internet ap-plications, satellite communications are gradually shifting from a complementary role to becoming a fully integrated component of terrestrial communications networks. This paper firstly introduces the development of satellite commu-nications, mobile communications and the global space-terrestrial integrated network. We then propose the functional architecture and network architecture for the integration of satellite communications and terrestrial mobile commu-nications based on 5G core networks. Finally, in order to support the network of the future, four key technologies are presented, a space-terrestrial integrated air interface design, a multi-band space-terrestrial integrated transmission waveform design, space-terrestrial integrated switching and routing technology, along with spectrum sharing and inter-ference coordination technology, all necessary for the development of space-terrestrial integrated networks.

Nonlinear interactions are recognized as potential resources for quantum metrology, facilitating parameter estimation precisions that scale as the exponential Heisenberg limit of $2^{-N}$. We explore such nonlinearity and propose an associated quantum measurement scenario based on the nonlinear interaction of $N$-probe entanglement generating form. This scenario provides an enhanced precision scaling of $D^{-N}/(N-1)!$ with $D > 2$ a tunable parameter. In addition, it can be readily implemented in a variety of experimental platforms and applied to measurements of a wide range of quantities, including local gravitational acceleration $g$, magnetic field, and its higher-order gradients.

The demand of new marine applications,such as ocean observation,polar scientific research,autonomous ship navigation,ship dynamic tracking,etc.,for the space-integrated-ground information network was analyzed.The typical marine applications,such as ocean remote sensing data relay,space-based internet of things of ocean observation platform,safety supervision of ships in the middle and far seas were proposed.Through the demonstration and promotion of the space-ground integrated information network marine application,we can promote the eff ective integration of the marine application and the Space-Ground Integrated Information Network,improve the comprehensive level of marine informatization,and help the rapid and stable development of China’s marine economy.

Laser communication has the characteristics of wide bandwidth, high data rate, and low power consumption, which is an important way to realize the information exchange of large amount. However, the transmission quality is deeply affected by atmospheric absorption, scattering, turbulence, and background light, which bring certain challenges to its reliability. This paper firstly summarizes the mathematical models of the main factors, and simulates the error rate of the incoherent optical link under the influence of beam wander, beam scintillation, and beam spreading. Finally, the paper further proposes a full-element BER analysis model including the influence of atmospheric turbulence, absorption and scattering, and background light.

With the development of technology, the demand for better image resolution is growing. The common method to achieve higher resolution is to increase the aperture of the lens. However, for satellites, resources are limited and the cost of launching is high, which makes it difficult to implement optical systems with larger apertures. In this paper, methods are analyzed, where by applying the optical synthetic aperture imaging technique for a group of small satellites, similar resolution of a single large aperture system is achieved. Difficulties and suggestions are given and fully discussed.

A millimeter wave system with commercially available and affordable data conversion devices is presented in this paper for achieving high-speed and low-cost wireless communications.By adopting the proposed dual pulse shaping (DPS) transmission scheme, the system can achieve full Nyquist rate transmission with only half of the sampling rate required by conventional Nyquist pulse shaping.Structures of the DPS transmitter and receiver are described and effective symbol rate equalization techniques suitable for DPS transmission are presented.Simulation results with two sets of practical dual spectral shaping pulses are also provided to compare system performance with the conventional Nyquist pulse shaping system.

The concept of complementary Nyquist pulse is introduced in this paper. Making use of a half rate Nyquist pulse and its complementary one, a dual pulse shaping transmission scheme is proposed, which achieves full Nyquist rate transmission with only a half of the sampling rate required by conventional Nyquist pulse shaping. This is essential for realizing high-speed digital communication systems with available and affordable data conversion devices. The condition for cross-symbol interference free transmission with the proposed dual pulse shaping is proved in theory, and two classes of ideal complementary Nyquist pulses are formulated assuming raised-cosine pulse shaping. Simulation results are also presented to demonstrate the improved spectral efficiency with dual pulse shaping and compare other system performance against conventional Nyquist pulse shaping.

Based on a one-dimensional double-well superlattice with a unit filling of ultracold atoms per site, we propose a scheme to generate scalable entangled states in the superlattice through symmetry-protected resonant lattice shaking. Our scheme utilizes periodic lattice modulations with a specific two-body exchange symmetry to entangle two atoms in each unit cell with respect to their orbital degree of freedom, and the complete atomic system in the superlattice becomes a cluster of bipartite entangled atom pairs. To demonstrate this we perform ab initio quantum dynamical simulations using the multilayer multiconfiguration time-dependent Hartree method for mixtures, which accounts for all correlations among the atoms. The proposed clusters of bipartite entanglements manifest as an essential resource for various quantum applications, such as measurement-based quantum computation. The lattice shaking scheme to generate this cluster possesses advantages such as a high scalability, fast processing speed, rich controllability on the target entangled states, and accessibility within current experimental techniques.