The current satellite communications (SatComs) systems are composed of a large number of satellites, beams and terrestrial devices. Due to their multinode dynamic nature, the usage of frequency resources is variable, complex and difficult to characterize. In particular, with the development of satellite-borne phased array antenna technology, SatCom beams carrying different frequencies are directionally and dynamically distributed in global scale. Mapping and locating the spatial beam distributions of communication satellite (comm-satellite) are the bases of intersystem cofrequency interference mitigation and spatial frequency reuse. In this paper, we design a data selection–multiparameter fitting iteration (DS-MFI) algorithm on the basis of ground-based omnidirectional antennas. The proposed approach can effectively map the spatial distribution of comm-satellite's beam, including satellite transmitter position, equal-gain off-axis angle, and beam pointing in azimuth and elevation. Simulation results verify the effectiveness of the proposed approach for satellites with fixed or steerable beams at different altitudes. Furthermore, the results become increasingly accurate as the dense of ground omni-antenna increases.
{"title":"Mapping spatial distribution of comm-satellite's beam based on ground omni-antennas","authors":"Zixuan Ren, Jin Jin, Wei Li, Yafeng Zhan","doi":"10.1002/sat.1473","DOIUrl":"10.1002/sat.1473","url":null,"abstract":"<div>\u0000 \u0000 <p>The current satellite communications (SatComs) systems are composed of a large number of satellites, beams and terrestrial devices. Due to their multinode dynamic nature, the usage of frequency resources is variable, complex and difficult to characterize. In particular, with the development of satellite-borne phased array antenna technology, SatCom beams carrying different frequencies are directionally and dynamically distributed in global scale. Mapping and locating the spatial beam distributions of communication satellite (comm-satellite) are the bases of intersystem cofrequency interference mitigation and spatial frequency reuse. In this paper, we design a data selection–multiparameter fitting iteration (DS-MFI) algorithm on the basis of ground-based omnidirectional antennas. The proposed approach can effectively map the spatial distribution of comm-satellite's beam, including satellite transmitter position, equal-gain off-axis angle, and beam pointing in azimuth and elevation. Simulation results verify the effectiveness of the proposed approach for satellites with fixed or steerable beams at different altitudes. Furthermore, the results become increasingly accurate as the dense of ground omni-antenna increases.</p>\u0000 </div>","PeriodicalId":50289,"journal":{"name":"International Journal of Satellite Communications and Networking","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2023-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45029380","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Delay‐tolerant networking (DTN) bundle protocol is considered one of the best transmission protocols to be used in space communications by NASA. There are studies that evaluated the performance, measuring the total transfer time of a complete file from sender to receiver, of the DTN protocol via simulation or emulated experiments beyond the real space‐based experiences. In addition, there is a very few additional research works available for the modeling of the Licklider transmission protocol (LTP). However, these past studies on LTP modeling are implemented as a Logarithmic approach that is based on the calculation of loss segments in file delivery. In this work, the approach is investigated in a different manner. Specifically, the performance model was created based on the probability of the segment's successful delivery on the LTP. Moreover, the original model is enhanced via introducing a burst of transfer and equal interval distribution of signaling segments, specifically check point (CP), along with the retransmission time out (RTO). The results from the developed model for the original DTN protocol and enhanced versions align with the results obtained by PC‐based testbeds.
{"title":"Performance modeling of Licklider transmission protocol (LTP) via proactive transmission of signaling segments in deep-space network","authors":"Hacer Varol","doi":"10.1002/sat.1454","DOIUrl":"https://doi.org/10.1002/sat.1454","url":null,"abstract":"Delay‐tolerant networking (DTN) bundle protocol is considered one of the best transmission protocols to be used in space communications by NASA. There are studies that evaluated the performance, measuring the total transfer time of a complete file from sender to receiver, of the DTN protocol via simulation or emulated experiments beyond the real space‐based experiences. In addition, there is a very few additional research works available for the modeling of the Licklider transmission protocol (LTP). However, these past studies on LTP modeling are implemented as a Logarithmic approach that is based on the calculation of loss segments in file delivery. In this work, the approach is investigated in a different manner. Specifically, the performance model was created based on the probability of the segment's successful delivery on the LTP. Moreover, the original model is enhanced via introducing a burst of transfer and equal interval distribution of signaling segments, specifically check point (CP), along with the retransmission time out (RTO). The results from the developed model for the original DTN protocol and enhanced versions align with the results obtained by PC‐based testbeds.","PeriodicalId":50289,"journal":{"name":"International Journal of Satellite Communications and Networking","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50122653","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Two subsequent World Radiocommunication Conferences, held in 2015 and 2019, have concluded the frequency allocation in VHF bands for the two-way maritime VHF Data Exchange System (VDES) via terrestrial and satellite radio frequency links respectively. The modernization and digital evolution of maritime communications was initiated in 1990's by adopting Automatic Identification Systems (AIS) for ship to shore, ship to ship and shore to ship communications for a variety of applications, targeting safety at sea. The frequency allocation for VDES has been a significant step forward toward achieving the same goal by facilitating solutions for enhanced navigation, broadcasting essential information and many other emerging applications.
The allocation of frequencies at WRC-19 for VDES via satellite (VDE-SAT), reduced regulatory risks in the deployment of VDES for two-way communications, to and from vessels via satellite. At the same time, the allocated frequency plan has raised new technical challenges for the development of space segment technologies aiming at feasible and viable solutions for end-to-end system deployment. This has made VDES an area of active research seeking academic as well as industrial solutions for end-to-end VDES terrestrial and satellite components sharing common system resources.
The development and deployment of AIS services in the 1990s were primarily intended to function as a tool for ship identification, collision avoidance and vessel traffic monitoring. However, the AIS success in terms of large-scale proliferation and feasibility quickly spawned a host of additional applications, which in turn led to the birth of the Application Specific Messages (ASM) concept. The standardization of ASM allowed for even more innovative use of the AIS technology and increased traffic on the AIS channels. Thus, in the 2000s, the traffic load on the AIS channels in dense shipping areas increased significantly. To avoid channel overload and possible loss of safety critical AIS messages, it was deemed logical to relocate non-safety related services away from the AIS channels. The simple solution for that was to move the ASM messages off the AIS channels. In the process of defining the spectrum requirements for ASM, additional maritime communication applications surfaced. As they could not all be accommodated by ASMs, the concept of VHF Data Exchange (VDE) was defined and the VHF Data Exchange System (VDES) was born.
In essence, the VDES provides a variety of means for the exchange of data between maritime stations, ship-to-ship, ship-to-shore, shore-to ship, ship-to-satellite and satellite-to-ship. The VDES is a multi-component system comprising of the automatic identification system (AIS), application specific messages (ASM) and VHF data exchange (VDE) in the VHF maritime mobile band (156.025-162.025 MHz). Although primarily a terrestrial system, VDES also allow for satellite use.1, 2 In par
{"title":"IJSC&N Special Issue “Opportunities and challenges of maritime VHF data exchange systems”: Guest editorial message","authors":"Nader Alagha, Lars Løge","doi":"10.1002/sat.1470","DOIUrl":"10.1002/sat.1470","url":null,"abstract":"<p>Two subsequent World Radiocommunication Conferences, held in 2015 and 2019, have concluded the frequency allocation in VHF bands for the two-way maritime VHF Data Exchange System (VDES) via terrestrial and satellite radio frequency links respectively. The modernization and digital evolution of maritime communications was initiated in 1990's by adopting Automatic Identification Systems (AIS) for ship to shore, ship to ship and shore to ship communications for a variety of applications, targeting safety at sea. The frequency allocation for VDES has been a significant step forward toward achieving the same goal by facilitating solutions for enhanced navigation, broadcasting essential information and many other emerging applications.</p><p>The allocation of frequencies at WRC-19 for VDES via satellite (VDE-SAT), reduced regulatory risks in the deployment of VDES for two-way communications, to and from vessels via satellite. At the same time, the allocated frequency plan has raised new technical challenges for the development of space segment technologies aiming at feasible and viable solutions for end-to-end system deployment. This has made VDES an area of active research seeking academic as well as industrial solutions for end-to-end VDES terrestrial and satellite components sharing common system resources.</p><p>The development and deployment of AIS services in the 1990s were primarily intended to function as a tool for ship identification, collision avoidance and vessel traffic monitoring. However, the AIS success in terms of large-scale proliferation and feasibility quickly spawned a host of additional applications, which in turn led to the birth of the Application Specific Messages (ASM) concept. The standardization of ASM allowed for even more innovative use of the AIS technology and increased traffic on the AIS channels. Thus, in the 2000s, the traffic load on the AIS channels in dense shipping areas increased significantly. To avoid channel overload and possible loss of safety critical AIS messages, it was deemed logical to relocate non-safety related services away from the AIS channels. The simple solution for that was to move the ASM messages off the AIS channels. In the process of defining the spectrum requirements for ASM, additional maritime communication applications surfaced. As they could not all be accommodated by ASMs, the concept of VHF Data Exchange (VDE) was defined and the VHF Data Exchange System (VDES) was born.</p><p><span>In essence, the VDES provides a variety of means for the exchange of data between maritime stations, ship-to-ship, ship-to-shore, shore-to ship, ship-to-satellite and satellite-to-ship. The VDES is a multi-component system comprising of the automatic identification system (AIS), application specific messages (ASM) and VHF data exchange (VDE) in the VHF maritime mobile band (156.025-162.025 MHz). Although primarily a terrestrial system, VDES also allow for satellite use.<span><sup>1, 2</sup></span> In par","PeriodicalId":50289,"journal":{"name":"International Journal of Satellite Communications and Networking","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2022-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/sat.1470","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41406788","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Helka-Liina Määttänen, Jonas Sedin, Sergio Parolari, Robert S. Karlsson
In Release 17, 3GPP introduced adaptations and enhancements to the 5G new radio (NR) specification to support non-terrestrial networks (NTNs) operation. The main challenges were due to long propagation delays, especially in GEO deployments, and the movement of the satellites in LEO deployments. In this paper, we give an overview of the protocol adaptations to support NTNs. The main user plane protocol adaptations include changes to random access and hybrid automatic repeat request to due long propagation delays. The control plane protocol adaptations include a variety of mobility related enhancements for user equipment.
{"title":"Radio interface protocols and radio resource management procedures for 5G new radio non-terrestrial networks","authors":"Helka-Liina Määttänen, Jonas Sedin, Sergio Parolari, Robert S. Karlsson","doi":"10.1002/sat.1469","DOIUrl":"10.1002/sat.1469","url":null,"abstract":"<div>\u0000 \u0000 <p>In Release 17, 3GPP introduced adaptations and enhancements to the 5G new radio (NR) specification to support non-terrestrial networks (NTNs) operation. The main challenges were due to long propagation delays, especially in GEO deployments, and the movement of the satellites in LEO deployments. In this paper, we give an overview of the protocol adaptations to support NTNs. The main user plane protocol adaptations include changes to random access and hybrid automatic repeat request to due long propagation delays. The control plane protocol adaptations include a variety of mobility related enhancements for user equipment.</p>\u0000 </div>","PeriodicalId":50289,"journal":{"name":"International Journal of Satellite Communications and Networking","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2022-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47044461","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Xin Li, Yongjun Li, Shanghong Zhao, Hanling Tang, Long Shao
Due to the rapid development of satellite laser communication technology, free-space optical (FSO) links present a promising alternative to traditional radio frequency (RF) links. In this paper, taking the influence of weather factors into consideration, we investigate the performance of the hybrid FSO/RF links where the feeder link operates in the FSO band and the user link operates in the hybrid FSO/RF band. Specifically, the FSO feeder link is modeled by the gamma–gamma distribution in the presence of beam wander and pointing error, and the detection method adopts either the intensity modulation with direct intensity (IM/DD) or heterodyne detection. The RF user link is assumed to follow the shadowed Rician model. In addition, in order to improve the transmission rate of the link under the time-varying satellite–terrestrial channel, a rate adaptation scheme is proposed. The performance of the system under study is evaluated in terms of the outage probability, average bit error rate (BER), and average transmission rate. Our results provide some important insights, for example, (1) due to the constraints of the feeder link and weather factors, there is an upper limit on the outage performance and bit error rate of the hybrid link; (2) the adaptive transmission strategy can significantly improve the transmission rate of the link compared with traditional design.
{"title":"Performance analysis of weather-dependent satellite–terrestrial network with rate adaptation hybrid free-space optical and radio frequency link","authors":"Xin Li, Yongjun Li, Shanghong Zhao, Hanling Tang, Long Shao","doi":"10.1002/sat.1468","DOIUrl":"10.1002/sat.1468","url":null,"abstract":"<div>\u0000 \u0000 <p>Due to the rapid development of satellite laser communication technology, free-space optical (FSO) links present a promising alternative to traditional radio frequency (RF) links. In this paper, taking the influence of weather factors into consideration, we investigate the performance of the hybrid FSO/RF links where the feeder link operates in the FSO band and the user link operates in the hybrid FSO/RF band. Specifically, the FSO feeder link is modeled by the gamma–gamma distribution in the presence of beam wander and pointing error, and the detection method adopts either the intensity modulation with direct intensity (IM/DD) or heterodyne detection. The RF user link is assumed to follow the shadowed Rician model. In addition, in order to improve the transmission rate of the link under the time-varying satellite–terrestrial channel, a rate adaptation scheme is proposed. The performance of the system under study is evaluated in terms of the outage probability, average bit error rate (BER), and average transmission rate. Our results provide some important insights, for example, (1) due to the constraints of the feeder link and weather factors, there is an upper limit on the outage performance and bit error rate of the hybrid link; (2) the adaptive transmission strategy can significantly improve the transmission rate of the link compared with traditional design.</p>\u0000 </div>","PeriodicalId":50289,"journal":{"name":"International Journal of Satellite Communications and Networking","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2022-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45472002","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Since 2017, 3rd Generation Partnership Program (3GPP) is working on integration of satellite communication in 3GPP. This paper discusses the results of the work on service and network architecture aspects in 3GPP Technical Specification Group (TSG) Service and System Aspects (SA) and 3GPP TSG Core Networks and Terminals (CT). This paper does not discuss radio aspects as are specified in 3GPP TSG radio access network (RAN). 3GPP first specified requirements and use cases for satellite access. Subsequently, architecture and protocol specifications were created for integration scenarios, direct access, network selection, mobility management, and satellite backhaul with quality of service (QoS). Also, impacts of regulatory aspects on satellite integration have been discussed in 3GPP. With the completion of Release 17, 3GPP specifications are now ready for implementation of integrated 5G satellite networks. 3GPP will continue with further development of satellite integration in Release 18 and Release 19.
{"title":"Network aspects of integrating 5G and satellite communication","authors":"Toon Norp, Jean-Yves Fine, Relja Djapic","doi":"10.1002/sat.1463","DOIUrl":"10.1002/sat.1463","url":null,"abstract":"<div>\u0000 \u0000 <p>Since 2017, 3rd Generation Partnership Program (3GPP) is working on integration of satellite communication in 3GPP. This paper discusses the results of the work on service and network architecture aspects in 3GPP Technical Specification Group (TSG) Service and System Aspects (SA) and 3GPP TSG Core Networks and Terminals (CT). This paper does not discuss radio aspects as are specified in 3GPP TSG radio access network (RAN). 3GPP first specified requirements and use cases for satellite access. Subsequently, architecture and protocol specifications were created for integration scenarios, direct access, network selection, mobility management, and satellite backhaul with quality of service (QoS). Also, impacts of regulatory aspects on satellite integration have been discussed in 3GPP. With the completion of Release 17, 3GPP specifications are now ready for implementation of integrated 5G satellite networks. 3GPP will continue with further development of satellite integration in Release 18 and Release 19.</p>\u0000 </div>","PeriodicalId":50289,"journal":{"name":"International Journal of Satellite Communications and Networking","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2022-12-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46956352","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
With the development of space information network (SIN), new network applications are emerging. Satellites are not only used for storage and transmission but also gradually used for calculation and analysis, so the demand for resources is increasing. But satellite resources are still limited. Mobile edge computing (MEC) is considered an effective technique to reduce the pressure on satellite resources. To solve the problem of task execution delay caused by limited satellite resources, we designed Space Mobile Edge Computing Network (SMECN) architecture. According to this architecture, we propose a resource scheduling method. First, we decompose the user tasks in SMECN, so that the tasks can be assigned to different servers. An improved ant colony resource scheduling algorithm for SMECN is proposed. The heuristic factors and pheromones of the ant colony algorithm are improved through time and resource constraints, and the roulette algorithm is applied to route selection to avoid falling into the local optimum. We propose a dynamic scheduling algorithm to improve the contract network protocol to cope with the dynamic changes of the SIN and dynamically adjust the task execution to improve the service capability of the SIN. The simulation results show that when the number of tasks reaches 200, the algorithm proposed in this paper takes 17.52% less execution time than the Min-Min algorithm, uses 9.58% less resources than the PSO algorithm, and achieves a resource allocation rate of 91.65%. Finally, introducing dynamic scheduling algorithms can effectively reduce task execution time and improve task availability.
{"title":"Resource scheduling in mobile edge computing using improved ant colony algorithm for space information network","authors":"Yufei Wang, Jun Liu, Yu Tong, Qingwen Yang, Yanyi Liu, Hanbo Mou","doi":"10.1002/sat.1467","DOIUrl":"10.1002/sat.1467","url":null,"abstract":"<div>\u0000 \u0000 <p>With the development of space information network (SIN), new network applications are emerging. Satellites are not only used for storage and transmission but also gradually used for calculation and analysis, so the demand for resources is increasing. But satellite resources are still limited. Mobile edge computing (MEC) is considered an effective technique to reduce the pressure on satellite resources. To solve the problem of task execution delay caused by limited satellite resources, we designed Space Mobile Edge Computing Network (SMECN) architecture. According to this architecture, we propose a resource scheduling method. First, we decompose the user tasks in SMECN, so that the tasks can be assigned to different servers. An improved ant colony resource scheduling algorithm for SMECN is proposed. The heuristic factors and pheromones of the ant colony algorithm are improved through time and resource constraints, and the roulette algorithm is applied to route selection to avoid falling into the local optimum. We propose a dynamic scheduling algorithm to improve the contract network protocol to cope with the dynamic changes of the SIN and dynamically adjust the task execution to improve the service capability of the SIN. The simulation results show that when the number of tasks reaches 200, the algorithm proposed in this paper takes 17.52% less execution time than the Min-Min algorithm, uses 9.58% less resources than the PSO algorithm, and achieves a resource allocation rate of 91.65%. Finally, introducing dynamic scheduling algorithms can effectively reduce task execution time and improve task availability.</p>\u0000 </div>","PeriodicalId":50289,"journal":{"name":"International Journal of Satellite Communications and Networking","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2022-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47345543","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Li Li, Xiaosong Zheng, Mingyi He, Fan Jin, Tianjiao Xie, Haiyi Cao
As LEO (Low Earth Orbit) high-resolution Earth observation satellite needs to transmit a large amount of remote sensing data from the satellite to the ground station, higher downlink capacity still poses a severe challenge to LEO. Therefore, variable coding and modulation (VCM) has become an important scheme to optimize the performance of satellite downlink. In this paper, the downlink VCM system of China Earth observation satellite is studied for the first time. By evaluating the free space loss of the satellite downlink path, a VCM-based satellite downlink system is designed, and a DVB-S2 BCH-LDPC encoded variable bit rate high-order MAPSK modulator is implemented. The maximum channel bit rate can reach 3.5 Gbps. Then, the experimental results of Gaofen-7 satellite, which was launched in November 2019, are carried out which showed that our design method effectively meets the design requirements, and the performance is verified.
{"title":"Design and implementation of variable coding and modulation for LEO high-resolution Earth observation satellite","authors":"Li Li, Xiaosong Zheng, Mingyi He, Fan Jin, Tianjiao Xie, Haiyi Cao","doi":"10.1002/sat.1465","DOIUrl":"10.1002/sat.1465","url":null,"abstract":"<div>\u0000 \u0000 <p>As LEO (Low Earth Orbit) high-resolution Earth observation satellite needs to transmit a large amount of remote sensing data from the satellite to the ground station, higher downlink capacity still poses a severe challenge to LEO. Therefore, variable coding and modulation (VCM) has become an important scheme to optimize the performance of satellite downlink. In this paper, the downlink VCM system of China Earth observation satellite is studied for the first time. By evaluating the free space loss of the satellite downlink path, a VCM-based satellite downlink system is designed, and a DVB-S2 BCH-LDPC encoded variable bit rate high-order MAPSK modulator is implemented. The maximum channel bit rate can reach 3.5 Gbps. Then, the experimental results of Gaofen-7 satellite, which was launched in November 2019, are carried out which showed that our design method effectively meets the design requirements, and the performance is verified.</p>\u0000 </div>","PeriodicalId":50289,"journal":{"name":"International Journal of Satellite Communications and Networking","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2022-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49454558","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ana Custura, Tom Jones, Raffaello Secchi, Gorry Fairhurst
Satellite networks usually use in-network methods (such as Performance Enhancing Proxies for TCP) to adapt the transport to the characteristics of the forward and return paths. QUIC is a transport protocol that prevents the use of in–network methods. This paper explores the use of the recently–standardised IETF QUIC protocol with a focus on the implications on performance when using different acknowledgement policies to reduce the number of packets and volume of bytes sent on the return path. Our analysis evaluates a set of ACK policies for three IETF QUIC implementations, examining performance over cellular, terrestrial and satellite networks. It shows that QUIC performance can be maintained even when sending fewer acknowledgements, and recommends a new QUIC acknowledgement policy that adapts QUIC's ACK Delay value based on the path RTT to ensure timely feedback. The resulting policy is shown to reduce the volume/rate of traffic sent on the return path and associated processing costs in endpoints, without sacrificing throughput.
{"title":"Reducing the acknowledgement frequency in IETF QUIC","authors":"Ana Custura, Tom Jones, Raffaello Secchi, Gorry Fairhurst","doi":"10.1002/sat.1466","DOIUrl":"10.1002/sat.1466","url":null,"abstract":"<p>Satellite networks usually use in-network methods (such as Performance Enhancing Proxies for TCP) to adapt the transport to the characteristics of the forward and return paths. QUIC is a transport protocol that prevents the use of in–network methods. This paper explores the use of the recently–standardised IETF QUIC protocol with a focus on the implications on performance when using different acknowledgement policies to reduce the number of packets and volume of bytes sent on the return path. Our analysis evaluates a set of ACK policies for three IETF QUIC implementations, examining performance over cellular, terrestrial and satellite networks. It shows that QUIC performance can be maintained even when sending fewer acknowledgements, and recommends a new QUIC acknowledgement policy that adapts QUIC's ACK Delay value based on the path RTT to ensure timely feedback. The resulting policy is shown to reduce the volume/rate of traffic sent on the return path and associated processing costs in endpoints, without sacrificing throughput.</p>","PeriodicalId":50289,"journal":{"name":"International Journal of Satellite Communications and Networking","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2022-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/sat.1466","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48151672","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Inigo del Portillo, Sydney I. Dolan, Bruce G. Cameron, Edward F. Crawley
The rise of the commercial space industry has resulted in the development of mega-constellations that promise to provide global broadband. These constellations capitalize on advancements in technology, improved modeling capabilities, and reductions in launch cost. One of the significant open questions is whether these constellations will significantly increase access for uncovered and underserved communities, in addition to serving existing markets. This paper analyzes which constellation characteristics provide the best global coverage at the lowest operational cost. First, we present the demand model that assesses the number of under-served and uncovered users in a given region. Then, we present a genetic algorithm used to identify potential constellations. Finally, we conclude by identifying which characteristics are the most promising for broadband constellations, as well as predictions of how the market will develop in the coming years. Our analysis has found that geostationary (GEO) and medium Earth orbit (MEO) satellite constellations have the highest likelihood of profitability. LEO networks are on average 27% more expensive, but if designed wisely, they can be competitive. Our work shows that there are diminishing returns with large constellations, and that it is more cost effective to have a small number of highly capable satellites, rather than many low complexity satellites. Key technologies like high frequency bands and miniaturization of components can lead to further cost reductions and increase the competitiveness of LEO constellations.
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