Multidimensional resources management enhances the efficiency of low-Earth orbit (LEO) satellite systems by dynamically allocating wireless resources. However, the majority of existing studies have overlooked the evolutionary trend of terrestrial terminals (TTs) from homogeneous to heterogeneous types. For instance, energy efficiency (EE) requirements for TTs inherently vary due to differences in their operating environments and deployment costs. Thus, this article investigates the design of beam hopping (BH) patterns, frequency allocation, and power control for LEO satellite uplinks, considering the diverse EE sensitivity (EES) among TTs. Specifically, a resource management problem is formulated to maximize the weighted sum EE, which captures the differences in EES among TTs. Next, an undirected graph is constructed based on EES and spatial isolation, and matching algorithms are proposed according to the many-to-one matching theory to obtain BH patterns. After that, to solve the joint frequency allocation and power control problem, a penalty function is applied to handle the binary variable utilized for expressing frequency allocation. Finally, quadratic transform and minorize–maximization are employed to concave the original problem, which guarantees to obtain a suboptimal solution. Simulation results demonstrate that proposed BH design methods provide a higher optimization ceiling for joint resources management than relevant benchmarks. Besides, the proposed uplink resources management significantly improves the EE by 34% in LEO satellite uplink compared with ignoring EES scheme. This work establishes a novel paradigm for energy-efficient uplink resource management in heterogeneous LEO systems.

The large-scale Low Earth Orbit (LEO) satellite communication systems are considered the most promising communication technologies in satellite-terrestrial integrated networks. LEO satellite systems have low latency, high throughput and wide coverage, which means they can provide telecommunication services for rescue and disaster scenarios. Since the LEO satellite communication systems and IMT systems are envisaged to share the same spectrum, the potential harmful interference issues must be analyzed. In this paper, the Walker constellation model is adopted in the satellite constellation design. Considering the large-scale deployment of LEO satellite systems and IMT systems, millions of base stations are scattered all over the place. Furthermore, we aim at evaluating the mutual interference of two systems in the Ka band and utilize terrain data to deploy IMT systems in the Contiguous United States. Specifically, an innovative method called electronic fences is proposed in the paper, which is conducive to alleviating the interference in satellite-terrestrial communication systems.

As the high demand for super-large connection, ultra-broad bandwidth and ultra-low latency of the future 6G mobile communication system, massive MIMO technology is crucial to the future development of IMT industry. The application of space-borne digital phased array antenna makes satellite communication feasible achieving massive MIMO. This paper mainly deals with simulation methodology of satellite- borne phased array antennas. It is appied to such simulations as coexistence, system, link and so on.

With the commercialization of International Mobile Telecommunications (IMT) technology, this paper studies the problem of ensuring coexistence between new frequency bands and existing satellite systems, which has led to an increasing demand for spectrum resources. Specifically, the research evaluates the potential interference between IMT and Earth-Exploration Satellite Service (passive)-EESS (passive) in the 10-10.5 GHz frequency band. This paper presents an innovative methodology for constructing a dynamic EESS (passive) system model based on orbital elements. In addition, the IMT system model was built by analyzing satellite imagery data. The results show different levels of interference sensitivity among passive sensors, highlighting the need to impose necessary restrictions on IMT systems to protect EESS (passive) systems. Overall, this paper introduces an innovative method for modeling the dynamic interaction between satellites and large-scale base stations, which is beneficial for analyzing the coexistence of IMT and EESS (passive) systems.

Sparse code multiple access (SCMA) is an up-and-coming non-orthogonal multiple access technology. The message passing algorithm (MPA) is utilized for multi-user signal detection in the SCMA system to achieve a performance close to the maximum a posterior algorithm. However, higher iterations will lead to the higher computational complexity of the MPA. In this paper, a dynamic threshold and stability judgment based MPA scheme (DTS-MPA) is proposed to reduce the computational complexity by simplifying the factor graph and reducing the number of iterations. Firstly, an adaptive dynamic threshold is set to minimize the number of iterations in the different channel state information. Secondly, an additional iteration is proposed to determine whether the variable nodes that meet the dynamic threshold reach stable convergence to improve the decoding reliability. Variable nodes that meet the above conditions will be decoded in advance. Numerical results show that the DTS-MPA can significantly reduce the computational complexity of the MPA and achieve a significant trade-off between bit error rate performance and computational complexity.

Beam hopping (BH) is the key technology to improve the system throughput and decrease the transmission delay in multibeam satellite systems. The objective of this study is to find a policy to maximise the expected long‐term resource utilisation. The BH illumination plan (BHIP) optimisation problem aimed at minimising the transmission delay is formulated and modelled as a partially observable Markov decision process. To tackle the issue of unknown dynamics and prohibitive computation, an artificial intelligence method named deep reinforcement learning (DRL) is first proposed to solve the BHIP problem in multibeam satellite systems. The proposed DRL‐BHIP algorithm considers a series of realistic conditions, including the traffic demands in spatial distribution and temporal variation, ModCod constraints, antenna radiation pattern and inter‐beam interference. The state reformulation concept is adopted to characterise the traffic spatial and temporal features. Simulation results show that the proposed DRL‐BHIP algorithm can decrease the transmission delay and improve the system throughput compared with existing algorithms.

Automatic modulation identification (AMI) is a significant technique to identify the modulation type of a received signal, and it is of great importance in information war and communication countermeasure. In this paper, we propose a constellation-wavelet transform automatic identifier (C-WT AMI) to identify the order of the received QAM signal. QAM is a widely used modulation type due to its high spectrum efficiency. From the characteristics of QAM constellation, we perform Haar wavelet transform of the received signal with the most appropriate scale, and then calculate the ratio of the maximum and minimum value q̌M of the Haar wavelet transform magnitude of received signal, and we can finally determine the signal order M according to the relationship between q̌M and M. To compute the most appropriate wavelet scale, estimating carrier frequency and sampling frequency is necessary. In this paper, we propose a method to estimating sampling frequency in practical engineering implement. Considering that distinct peaks may occur in the Haar wavelet transform magnitude due to symbol phase changes, and it could impact the identification correct rate, so an effective algorithm to eliminate the influence of the peaks is also proposed. Simulation results show that the proposed scheme is of good performance, and it can almost be inerrable when SNR>4dB. Besides, compared to the methods proposed in other papers, our scheme shows a better performance with higher correct rate.

As a promising technology to effectively mitigate interference and improve the performance of a wireless communication network, interference alignment (IA) has been attracted extensive concern. In order to solve the problem that perfect IA needs a large number of antennas and facing the cell selection, this paper proposes a partial interference alignment scheme based on user grouping for a network with multi-cell multi-user multiple- input and multiple-output (MIMO) under downlink transmission scenario. In the proposed scheme, the interference at different directions does not need to be aligned to the same subspace. Furthermore, each BS eliminates inter-user interference within its cell and the dominant interference to users in its neighboring cells. Analysis and simulation results show that the proposed approach outperforms the extension of grouping method in terms of antenna number and sum capacity.