Beam Hopping Research Articles

A Beam Hopping Scheme Based on Adaptive Beam Radius for LEO Satellites.

Toward the vision of seamless global connectivity in the 6G era, the non-terrestrial network (NTN) in space-air-ground integrated networks (SAGINs) network architecture is one of the highly promising solutions. From the perspective of relay nodes, NTN includes satellite nodes and space-based platform nodes. As a resource management technology in satellite communication, beam-hopping has garnered significant attention from researchers due to its effectiveness in ad-dressing the disparity between offered capacities and uneven terrestrial traffic demands. Recognizing that the larger beams offer broader coverage but the smaller ones provide better an-ti-interference capabilities and higher throughput, this paper introduces an adaptive cluster-ing-based approach. It provides large, medium, and small user beams to target ground users. The proposed algorithm aims to minimize total system latency and enhance system throughput. Sim-ulation results show that employing the proposed algorithm in the baseline model results in a 3.44% increase in system throughput and a 35.5% reduction in system latency. Furthermore, simulation results based on alternative models indicate that while the proposed algorithm may lead to a slight decrease in system throughput, it brings significant improvements in system latency.

Joint Beam Scheduling and Power Optimization for Beam Hopping LEO Satellite Systems

Joint Beam Scheduling and Power Optimization for Beam Hopping LEO Satellite Systems

Multi-Satellite Cooperative Load-Balancing Scheme Based on Dynamic Beam Coverage for LEO Beam Hopping Systems

Multi-Satellite Cooperative Load-Balancing Scheme Based on Dynamic Beam Coverage for LEO Beam Hopping Systems

Towards Beam Hopping and Power Allocation in Multi-Beam Satellite Systems With Parameterized Reinforcement Learning

Towards Beam Hopping and Power Allocation in Multi-Beam Satellite Systems With Parameterized Reinforcement Learning

High Performance Receiving and Processing Technology in Satellite Beam Hopping Communication

High Performance Receiving and Processing Technology in Satellite Beam Hopping Communication

Beam-Hopping-Based Resource Allocation in Integrated Satellite-Terrestrial Networks.

The integrated satellite-terrestrial network (ISTN) provides a promising solution to achieve high-data-rate and ubiquitous connectivity in next-generation communication networks. Considering the scarce spectrum resources and unevenly distributed traffic demands, we investigate the resource allocation algorithms for ISTNs, where the beam-hopping (BH)-based satellite system and terrestrial systems share the same frequency band. Taking advantage of the scheduling flexibility of BH technology, the dynamical protection zones are constructed to avoid co-channel interference and improve the spectrum efficiency. Since both spectrum efficiency and user fairness are the key optimization indexes in practical systems, two resource allocation problems are formulated to maximize the weighted sum of capacity (MWSC) and maximize the minimum capacity-to-demand ratio (MMCDR) of ISTNs, respectively. By reformulating the problems as mixed-integer linear programming problems, optimal solutions are obtained. To reduce the computational complexity, two greedy suboptimal algorithms are proposed for the MWSC and MMCDR, respectively. The simulation results show that the proposed algorithms achieve higher spectrum efficiency and guarantee fairness between the satellite and terrestrial systems. It is also shown that both the greedy algorithms perform similarly to the optimal algorithms while having much lower complexity.

Adaptive multibeam hopping in geo satellite networks with non-uniformly distributed ground users

This paper designs a novel low-complexity user-cluster grouping algorithm for adaptive beam hopping in geostationary satellite networks equipped with multibeam phased-array antennas. Each beam serves a cluster of users, and the challenge is to design a beam-hopping pattern where no beams are simultaneously serving nearby user clusters. We develop a line search procedure to identify near-optimum groupings for heterogeneous traffic demands. We provide a necessary condition to determine the boundaries of the line search space. Our approach employs exclusion regions around critical user clusters in congested areas, iterates a sequential congestion-based grouping algorithm, and applies a group-member-swapping procedure. It provides max-min fairness for ground users. Extensive numerical studies have shown that our user grouping algorithm produces near-optimum beam-hopping schedules with low outage probability. It achieves an improvement of up to 13dB in the worst-case signal-to-interference and noise ratio, and doubles the zero-outage data rate, compared to benchmark approaches.

Future satellite communications: Satellite constellations and connectivity from space

Satellite communications is currently undergoing a massive growth, with a rapid expansion in Low Earth Orbit (LEO) networks, and a range of new satellite technologies. Until very recently, satellite communication systems and terrestrial 5/6G wireless networks have been complementary distinct entities. There is now the opportunity to bring these networks together and deliver an integrated global coverage multi-service network. Achieving this will require solving some key research challenges, and leveraging new technologies including high frequency phased-array antennas, onboard processing, dynamic beam hopping, physical layer signal processing algorithms, transmission waveforms, and adaptive inter-satellite links and routing. By integrating seamlessly with terrestrial 5/6G networks and low altitude flying access points, future satellite networks promise to deliver universal connectivity on a global scale, overcoming geographical limitations. In this special issue, we focus on the future of satellite communications, exploring topics ranging from beam hopping and design to space routing and THz satellite communications. Our aim is to shed light on the potential of these emerging technologies and their role in reshaping the landscape of global connectivity.

Machine learning-inspired intelligent optimization for smart radio resource management in satellite communication networks to improve quality of service

Satellite communication networks are seeing a significant surge in traffic requirements. Nevertheless, the rise in traffic requirements is inconsistent across the service region because of the unequal distribution of consumers and fluctuations in traffic requirements during the day. Variable payload designs solve this issue by enabling the uneven allocation of payload resources to match the traffic requirement of each beam. Optimization-based Radio Resource Management (ORRM) has its high substantial efficiency demonstrated computational difficulty hinders its real-world deployment. This work explores the structure, execution, and uses of Machine Learning (ML) for resource allocation in satellite systems. The primary emphasis is on two systems: one that offers power, capacity, and beamwidth adaptability and provides temporal flexibility via beam hopping. The research examines and contrasts several ML methods suggested for these structures. The research determines whether training must be done online or offline depending on the features and needs of each ML method. The study analyzes the most suitable system structure and the pros and cons of each strategy.

Extended DL Coverage in SAGIN: Cell Association and Resource Allocation with Beam Hopping LEO

Extended DL Coverage in SAGIN: Cell Association and Resource Allocation with Beam Hopping LEO

Dynamic Beam Hopping and Resource Allocation for Non-Uniform Traffic Demand in NGSO Satellite Communication Systems

Dynamic Beam Hopping and Resource Allocation for Non-Uniform Traffic Demand in NGSO Satellite Communication Systems

Random Access Control and Beam Management Scheme for the 5G NR based Beam Hopping LEO Satellite Communication Systems

Random Access Control and Beam Management Scheme for the 5G NR based Beam Hopping LEO Satellite Communication Systems

Cluster-Based Beam Hopping for Energy Efficiency Maximization in Flexible Multibeam Satellite Systems

Cluster-Based Beam Hopping for Energy Efficiency Maximization in Flexible Multibeam Satellite Systems

A Unified NOMA Framework in Beam-Hopping Satellite Communication Systems

This paper investigates the application of a unified non-orthogonal multiple access framework in beam hopping (U-NOMA-BH) based satellite communication systems. More specifically, the proposed U-NOMA-BH framework can be applied to code-domain NOMA based BH (CD-NOMA-BH) and power-domain NOMA based BH (PD-NOMA-BH) systems. To satisfy dynamic-uneven traffic demands, we formulate the optimization problem to minimize the square of discrete difference by jointly optimizing power allocation, carrier assignment and beam scheduling. The non-convexity of the objective function and the constraint condition is solved through Dinkelbach's transform and variable relaxation. As a further development, the closed-from and asymptotic expressions of outage probability are derived for CD/PD-NOMA-BH systems. Based on approximated results, the diversity orders of a pair of users are obtained in detail. In addition, the system throughput of U-NOMA-BH is discussed in delay-limited transmission mode. Numerical results verify that: i) The gap between traffic requests of CD/PD-NOMA-BH systems appears to be more closely compared with orthogonal multiple access based BH (OMA-BH); ii) The CD-NOMA-BH system is capable of providing the enhanced traffic request and capacity provision; and iii) The outage behaviors of CD/PD-NOMA-BH are better than that of OMA-BH.

A high‐efficiency frequency synchronization scheme for low Earth orbit satellite communications based on dynamic game theory

SummaryThe rapid development of satellite internet networks has given rise to a new vision for the sixth generation of networking technology. However, the Doppler effect is relatively serious in satellite internet networks because a satellite moves quickly relative to a ground terminal. Therefore, there is an urgent need to study intelligent and dynamic synchronization methods to solve the problem of the rapidly changing Doppler frequency offset. Traditional methods do not consider the impact of spatial changes and typically focus on enhancing the estimation range or accuracy. We analyze various scenarios under phased array beam hopping and establish constraints between the terminal location, satellite ephemeris, subsatellite point track, elevation angle, and carrier frequency offset. We introduce dynamic game theory into frequency synchronization to optimize multiple Doppler estimation performance under rapidly changing channel conditions. We take the combination of carrier frequency offset estimation algorithm strategies at the current moment as the game entity. Simulation results demonstrate that the proposed method can achieve an estimation accuracy of 100 Hz and an estimation range of ±800 kHz. During the onboard test, the probability of achieving complete synchronization (when the synchronization success rate is 1) is 0.65, which is much higher than the 0.15 of the single method.

Multiobjective Optimization for Beam Hopping and Power Allocation in Dual Satellite Cooperative Transmission Networks

Since single satellite capacity is limited for hotspot areas, we propose a dual satellite (DS) cooperative transmission network to increase the number of served cells and improve the quality of service (QoS) in this article. We study the global beam hopping and power allocation in the proposed network, where the conflict between cell priority and latency is balanced. Due to the beam power impacting both cochannel interference and capacity, the two multiobjective problems are coupled. The plural method is introduced to simplify the coupled problems, which obtains a better QoS than the fixed-weight method. As the dimensionality of the beam hopping pattern increases with the number of cells, global beam hopping design is a dimensional explosion problem. The demand-weighted power (DWP)-adaptive particle marching (APM) algorithm includes roulette, stochastic exploration, and nonlinear weights strategies. It is proposed to handle high-dimensional problems and converge fast to better optimal solutions. The simulation results show that the DWP-APM algorithm performs better with a few particles than the four baseline algorithms. Compared with baseline algorithms, the DWP-APM algorithm reduces the computation time by 57% and improves the QoS level by 13.6% at least.

Beam position and beam hopping design for LEO satellite communications

Beam position and beam hopping design for LEO satellite communications

NOMA-based collaborative beam hopping frequency allocation mechanism for future LEO satellite systems

Low Earth orbit (LEO) satellite systems provide terrestrial users with services that are not limited by geographical location. However, the conflict between existing allocation schemes and the business variability between beams is becoming increasingly prominent. Beam hopping technology allows for a more flexible and versatile approach to satellite resource allocation. This paper proposes a beam hopping pattern optimization scheme that jointly considers the interference threshold distance and beam service priority, reducing the inter-beam co-channel interference (CCI). In the cluster area, a non-orthogonal multiple access (NOMA)-based collaborative beam hopping (NCBH) scheme is proposed to minimize the cell-edge user (CEU) interference. Since there is a difference in channel gain between the CEU and cellcenter user (CCU), this scheme forms a NOMA cluster to perform power domain multiplexing and formulates a NOMA cluster pairing strategy according to the user location to reduce the CCI of the CEU. After NOMA cluster pairing, the optimal carrier frequency of the NOMA cluster is selected by a reinforcement learning algorithm. The simulation results verify the excellent performance of the proposed NCBH scheme regarding the user's received power, transmission rate, and outage probability.

The Next Generation of Beam Hopping Satellite Systems: Dynamic Beam Illumination With Selective Precoding

Beam Hopping (BH) is a popular technique considered for next-generation multi-beam satellite communication system which allows a satellite focusing its resources on where they are needed by selectively illuminating beams. While beam illumination plan can be adjusted according to its needs, the main limitation of convectional BH is the adjacent beam avoidance requirement needed to maintain acceptable levels of interference. With the recent maturity of precoding technique, a natural way forward is to consider a dynamic beam illumination scheme with selective precoding, where large areas with high-demand can be covered by multiple active precoded beams. In this paper, we mathematically model such beam illumination design problem employing an interference-based penalty function whose goal is to avoid precoding whenever possible subject to beam demand satisfaction constraints. The problem can be written as a binary quadratic programming (BQP). Next, two convexification frameworks are considered namely: (i) A Semi-Definition Programming (SDP) approach particularly targeting BQP type of problems, and (ii) Multiplier Penalty and Majorization-Minimization (MPMM) based method which guarantees to converge to a local optimum. Finally, a greedy algorithm is proposed to alleviate complexity with minimal impact on the final performance. Supporting results based on numerical simulations show that the proposed schemes outperform the relevant benchmarks in terms of demand matching performance while minimizing the use of precoding.

Time‐space‐power allocation for enhanced IoT‐terminal services in cognitive satellite‐aerial networks

AbstractIn remote and inaccessible areas, the traffic request for Internet‐of‐Things (IoT) terminals is growing. This paper proposes a cognitive satellite‐aerial network (CSAN) to provide sufficient access services. The proposed CSAN consists of the primary beam‐hopping (BH) satellite and secondary aerial‐based station (ABS) systems. Since the two systems share spectrums, co‐channel interference (CCI) between the two systems is complicated, and the quality of service (QoS) is seriously degraded. To improve the QoS, the dynamic BH (DBH) pattern, ABS access in the time domain, and ABS power control in the power domain are studied. First, based on the sparsity of the DBH pattern, the greedy quick tracking (GAT) algorithm is proposed to design the DBH pattern quickly. Then, subject to the DBH pattern, a greedy access monitor (GAM) algorithm is determined for timely ABS access and power control. Since each ABS only serves terminals within a suitable distance, the placement and terminal cluster of multi‐ABSs in the space domain are required to ensure full terminal coverage. Thus, the mutual selection K algorithm is proposed to save required ABS numbers and improve service fairness among terminal clusters. Simulation results demonstrate the efficacy of time‐space‐power allocation for enhanced IoT‐terminal services in the proposed CSAN.