Heterogeneous Satellite Networks Research Articles

Energy-aware Joint Route Selection and Resource Allocation in Heterogeneous Satellite Networks

Energy-aware Joint Route Selection and Resource Allocation in Heterogeneous Satellite Networks

High Reliable Uplink Transmission Methods in GEO–LEO Heterogeneous Satellite Network

As a significant component of non-terrestrial networks, satellite communication has gradually evolved into a heterogeneous topology where the network nodes are classified as low Earth orbit (LEO) and geostationary Earth orbit (GEO) nodes. Considering the advantage of low transmission delay of LEO satellites in a heterogeneous network, ground users are arranged to access LEO satellites in the first priority. By fully understanding the equivalent channel gain difference in the beam-edge and beam-center users, we develop non-orthogonal multiple access (NOMA) in an LEO network where different users are allocated in the same resource block. As a complementary strategy, the beam-edge user has the ability to connect the GEO satellite if the LEO links are not available. That is, the two users are served cooperatively by LEO and GEO satellites in an orthogonal manner. In this paper, we provide deep insights for the uplink transmission performance of NOMA and cooperative orthogonal multiple access methods. As a general metric, the analytical expressions of outage probability are derived and the diversity orders are also provided. The simulation results show that NOMA is capable of providing remarkable performance in low signal-to-noise ratio regions and is more promising when the channels are assumed to be ordered.

A Two-Step Handover Strategy for GEO/LEO Heterogeneous Satellite Networks Based on Multi-Attribute Decision Making

Low Earth Orbit (LEO) satellites can provide high-speed and low-delay services for terrestrial users; however, the rapid movement of LEO satellites and the insufficient size of the LEO constellations incurs the instability of the transmission links. The rapid movement of LEO satellites also leads to frequent handovers. Fortunately, GEO/LEO heterogeneous satellite systems can remedy this shortcoming. As the handover decision strategy which makes the selection among the available satellites will directly impact the performance of GEO/LEO heterogeneous satellite systems, we propose a two-step access and handover decision strategy for heterogeneous satellite networks in this paper. Firstly, a GEO/LEO network selection is carried out based on utility functions that reflect user’s QoS requirements. Then, the multi-attribute decision making (MADM) method is used to select the specific LEO satellite if users select LEO satellite network. We also propose an Importance-TOPSIS scheme to improve the weight setting for handover attributes. Simulation results show that the proposed method can reduce the number of handovers and the forced termination probability of the system, and the overall throughput of the system is also improved.

Computing Energy Efficiency for a Cognitive Heterogeneous Satellite Network Based on Interference Management

Computing Energy Efficiency for a Cognitive Heterogeneous Satellite Network Based on Interference Management

Reinforcement Learning Based Capacity Management in Multi-Layer Satellite Networks

The development of satellite networks is drawing much more attention in recent years due to the wide coverage ability. Composed of geosynchronous orbit (GEO), medium earth orbit (MEO), and low earth orbit (LEO) satellites, the satellite network is a three-layer heterogeneous network of high complexity, for which comprehensive theoretical analysis is still missing. In this paper, we investigate the problem of capacity management in the three-layer heterogeneous satellite network. We first construct the model of the network and propose a low-complexity method for calculating the capacity between satellites. Based on the time structure of the time expanded graph, the searching space is greatly reduced compared to traditional augmenting path searching strategies, which can significantly reduce the computing complexity. Then, based on Q-learning, we proposed a long-term optimal capacity allocation algorithm to optimize the long-term utility of the system. In order to reduce the storage and computing complexity, a learning framework with low-complexity is constructed while taking the properties of satellite systems into account. Finally, we analyze the capacity performance of the three-layer heterogeneous satellite network and also evaluate the proposed algorithms with numerical results.

Analysis of heterogeneous satellite networks with multi‐user detectors

SummaryIn this work, a heterogeneous network, where both terrestrial‐ and multiple spot beam‐based geosynchronous satellite networks use the same sub‐channel, is investigated. Moreover, the satellite uses same sub‐channel to serve users across all spot beams. Apart from inter spot beam interference, satellite users also receive strong interfering signal from the terrestrial base station. The satellite receivers manage the inter system interference (ie, interference from terrestrial network) while the inter spot beam interference is mitigated through precoding at the gateway. To be specific, the following interference‐aware detectors are used to mitigate the inter system interference: successive interference canceller (SIC) and joint decoder (JD). The proposed decoders are shown to achieve better data rate and bit error rate (BER) than the interference ignorant decoder at moderate to strong interference levels. Although JD and SIC achieve same sum rate at moderate and strong interference levels, JD is shown to allow the terrestrial user achieve higher data rate than SIC.

Interference management for spectral coexistence in a heterogeneous satellite network

SummaryWith the advent of the fifth generation of mobile radio communication by 2020, there will be many challenges such as increasing service demand with low delay in providing billions of end users called the satellite mobile users. It is expected that terrestrial communication systems will be faced with a dense network having many small cells anywhere and anytime. Therefore, there are some remote regions in the world where terrestrial systems cannot provide any services to end users. Furthermore, because of lack of spectral resources, it is very important that the spectrum is shared between satellite systems and terrestrial equipment by a suitable solution to interference management. In this paper, a heterogeneous satellite network that includes low earth orbit (LEO) satellite constellation and terrestrial equipment is proposed to provide low delay services. In this type of structure, interference management based on transmission power control between LEO satellite systems and mobile users is very important for obtaining high throughput. Moreover, in order to mitigate interference, transmission power control is shown based on noncooperative Stackelberg game under many subgames through pricing‐based algorithm and convex optimization method. Finally, the simulation results show that the performance of this study's system model will be improved through the proposed algorithm.

Assessment of Satellite Contacts Using Predictive Algorithms for Autonomous Satellite Networks

Upcoming Low Earth Orbit Satellite Networks will provide low-latency and high downlink capacity necessary for future broadband communications and Earth Observation missions. This architecture was proposed at the beginning of the 90's, although it has just recently re-gained popularity thanks to the so-called Mega-Constellations. This network is composed of satellites that have Inter-Satellite Links (ISL) to communicate between them. Due to the satellite motion, an ISL is a temporal contact between two satellites characterized by a lifetime in which the communication remains feasible. The determination of a route between distant satellites is a challenging problem in this context. However, the satellite follows a well-known deterministic orbit trajectory, being feasible the prediction of its position by propagating a trajectory model over time. The Contact Graph Routing protocol uses this feature to determine the evolution of the routes by pre-computing on-ground a planning of the satellite contacts. This centralized ground-dependent solution cannot be directly applied in the Internet of Satellites paradigm, which proposes the autonomous deployment of heterogeneous satellite networks without pre-assuming any specific satellite system architecture. Following this concept, the present work proposes a distributed algorithm by which a satellite predicts neighbor contacts, and generates a global contact plan without trajectory propagation. To achieve this solution, an ISL has been modeled as a “close approach” between two satellites, which is characterized by their relative motion. The present work details the predictive algorithm, and evaluates its performance in two scenarios with a hybrid satellite constellation and a mega-constellation.

The Next Generation Heterogeneous Satellite Communication Networks: Integration of Resource Management and Deep Reinforcement Learning

This article proposes an innovative resource management framework for the next generation heterogeneous satellite networks (HSNs), which can achieve cooperation between independent satellite systems and maximizing resource utilization. The key points of the proposed design lie in the architecture that supports the intercommunication between different satellite systems, and the SDN/NFV-based management offering the matching between resources and services. Based on the framework, we then apply deep reinforcement learning (DRL) into the system due to its strong ability in optimal matching. The two problems of multiobjective reinforcement learning and multiagent reinforcement learning are studied to adapt the development of the HSN. The combination of the DRL and resource allocation achieves integrated resource management across different satellite systems and achieves resource allocation in the HSN which can be implemented more flexibly and efficiently.

Caching in heterogeneous satellite networks with fountain codes

SummaryIn this paper, we investigate the performance of caching schemes based on fountain codes in a heterogeneous satellite network. We consider multiple cache‐aided hubs, which are connected to a geostationary satellite through backhaul links. With the aim of reducing the average number of transmissions over the satellite backhaul link, we propose the use of a caching scheme based on fountain codes. We derive a simple analytical expression of the average backhaul transmission rate and provide a tight upper bound on it. Furthermore, we show how the performance of the fountain code‐based caching scheme is similar to that of a caching scheme based on maximum distance separable codes.

Interference mitigation for a heterogeneous satellite network based on spatial angle and transmission power

Nowadays, with the explosive growth of users and devices, it is expected that new generation satellite system will support different communication demand around the world. Therefore, by increasing demand, hybrid satellite-terrestrial networks have been developed for achieving more coverage and capacity. Thus, in this paper, a LEO satellite constellation is deployed which includes LEO satellite systems and terrestrial equipment. Also, in order to manage the interference that is one of the main challenges in this network, Stackelberg game theory is used based on power control between LEO satellite systems and mobile users. To mitigate interference, two sub-games are provided based on pricing-based algorithm and convex optimization method. Finally, simulation results show that the performance of heterogeneous satellite network will be enhanced by the presented assumptions.

Spectrum planning and performance evaluation between heterogeneous satellite networks

A new network has been recently proposed for the provision of fixed broadband services via high altitude platform stations (HAPS) in the 48/47 GHz band. One of the critical issues of this technology is spectrum sharing with the fixed satellite service. This paper examines the effect of Earth-to-stratosphere co-channel interference produced by ground stations of HAPS network to geostationary orbit (GEO) satellite receivers and proposes an interference-to-noise (I/N) calculation model for the evaluation of the current HAPS ground stations power characteristics set by ITU-R. Analytical and simulation results for archetypal systems in realistic scenarios indicate that efficient use of the spectrum shared between heterogeneous HAPS and Fixed Satellite Networks is feasible. Certain consideration is needed prior to the HAPS network development in suburban areas for latitudes from 55° to 65°, and in rural areas for latitudes from 60° to 75°.

An applied research study for the provision of a QoS-oriented environment for voice and video services over satellite networks

The aim of this paper is to present a network solution to provide Quality of Service (QoS) guaranteed voice and video services over a satellite test-bed based on the TCP/IP protocol suite, oriented to distance learning. The scope of the solutions proposed is a small private satellite network where specific services (e.g. tele-education) are offered to the users. The paper describes the main operating steps followed to perform the tests. The target service requirements are identified and the configuration of devices and protocols are described in detail. The Integrated Services approach is utilized along with three different scheduling mechanisms at IP layer. A proper routing protocol to support multicast is used. The work is a part of a project called ‘Integration of Multimedia Services over Heterogeneous Satellite Networks’, which has been developed by the Italian National Consortium of Telecommunications (CNIT) and funded by the Italian Space Agency (ASI). The test-bed is composed of two remote sites, connected through a satellite link at 2 Mbits/s and by one site, where no satellite device is available, connected by using ISDN. The results reported allow to test the application of bandwidth reservation strategies originally studied for a terrestrial environment and to measure the consequent performance improvement. The use of both subjective metrics as mean opinion score (MOS) and objective metrics, as audio/video packet loss and average bit rate, to perform the investigation, allow mapping the measure of P-QoS (Perceived-Quality of Service) with quantities uninfluenced by personal opinions. The configurations used represent the result of an applied research project and provide an operative solution, inclusive of technical details, to guarantee high quality of service for audio/video applications.

TCP/IP-based multimedia applications and services over satellite links: experience from an ASI/CNIT project

This article describes the activity performed in the three-year project "Integration of Multimedia Services on Heterogeneous Satellite Networks," funded by the Italian Space Agency (ASI) and carried out by the Italian National Consortium for Telecommunications (CNIT). The description of the activity allows highlighting the problems, findings, and solutions in utilizing TCP/IP-based services and applications, such as audio-video transmission and Web browsing, via satellite channels. The article presents an experimental approach to provide QoS guarantees and to improve the performance of TCP over a satellite network based on the TCP/IP suite. The aim is to obtain a proper environment for data, voice, and video transmission oriented to a distance learning service that uses both audio-video applications and Web-based tools. The experimental scenario is made up of three remote LANs. Two of them are connected through a geostationary orbit satellite link in the Ka-band (20-30 GHz). The other LAN, located in a site where no satellite station is available, is connected through an ISDN link at 512 kb/s. Both subjective metrics such as mean opinion score and objective metrics such as throughput and overall transmission time have been used to evaluate the performance of the system and to get proper configurations able to guarantee a high QoS perceived by the users. The integrated services approach along with the resource reservation protocol were chosen to reserve the network resources at the IP level. A modified version of TCP has been proposed and utilized to reduce the download time during Web browsing and f.t.p. sessions. The measures reported have been obtained by real operative sessions.