To address the problem that Ka-band satellite communication signal transmission is easily affected by rainfall and terminal environment, combining the characteristics of high-speed movement of LEO satellites and the wave propagation characteristics of satellite-ground links, this paper establishes a Markov synthesis model of four-state satellite channels based on Ka-band that integrates rainfall attenuation and terminal shadow attenuation, and a scheme for adaptive coding and modulation selection based on the DVB-S2 standard is proposed. Based on this, a rainfall fading probability density function (PDF) based on the satellite elevation angle variation is derived, and a more efficient and streamlined set of modulation and coding(MODCOD) is obtained through simulations and calculations. The simulation results show that the proposed scheme not only effectively solves the problem of severe fading of the transmission signal due to rainfall, ground movement environment and satellite mobility but also significantly reduces the system complexity of the original DVB-S2 standard scheme with little loss of efficiency.
{"title":"Adaptive coding modulation selection optimisation scheme for Ka-band LEO mobile satellites","authors":"Hongrong Shen, Qian Ning, Bingcai Chen","doi":"10.1002/sat.1475","DOIUrl":"10.1002/sat.1475","url":null,"abstract":"<div>\u0000 \u0000 <p>To address the problem that Ka-band satellite communication signal transmission is easily affected by rainfall and terminal environment, combining the characteristics of high-speed movement of LEO satellites and the wave propagation characteristics of satellite-ground links, this paper establishes a Markov synthesis model of four-state satellite channels based on Ka-band that integrates rainfall attenuation and terminal shadow attenuation, and a scheme for adaptive coding and modulation selection based on the DVB-S2 standard is proposed. Based on this, a rainfall fading probability density function (PDF) based on the satellite elevation angle variation is derived, and a more efficient and streamlined set of modulation and coding(MODCOD) is obtained through simulations and calculations. The simulation results show that the proposed scheme not only effectively solves the problem of severe fading of the transmission signal due to rainfall, ground movement environment and satellite mobility but also significantly reduces the system complexity of the original DVB-S2 standard scheme with little loss of efficiency.</p>\u0000 </div>","PeriodicalId":50289,"journal":{"name":"International Journal of Satellite Communications and Networking","volume":"41 4","pages":"406-425"},"PeriodicalIF":1.7,"publicationDate":"2023-03-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46883963","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}
Satellite constellation design plays an important role in satellite networks. Network constellation system design can affect the effectiveness of current improvements of the communications link and the management of the entire network. The power requirement of the mobile stations and ground stations is very high in a geostationary Earth orbit communication system, which means the terrestrial terminal is hard to be made handheld for fifth generation mobile communications. The emergence of nongeostationary orbit satellites such as low Earth orbit satellites greatly compensates for the disadvantage of geostationary Earth orbit satellites. Based on the classical constellation design method, the orthogonal circular orbit constellation is proposed. The design objectives considered here are the following: global Earth coverage by low Earth orbit satellites, the duration of continuously covering one mobile station by one satellite is more than 9.57 min, the access satellite link duration time of the mobile station is more than 4.79 min, and the number of satellites and orbits is to be minimum.
{"title":"Satellite constellation design for 5G wireless networks of mobile communications","authors":"Ravandran Muttiah","doi":"10.1002/sat.1477","DOIUrl":"10.1002/sat.1477","url":null,"abstract":"<div>\u0000 \u0000 <p>Satellite constellation design plays an important role in satellite networks. Network constellation system design can affect the effectiveness of current improvements of the communications link and the management of the entire network. The power requirement of the mobile stations and ground stations is very high in a geostationary Earth orbit communication system, which means the terrestrial terminal is hard to be made handheld for fifth generation mobile communications. The emergence of nongeostationary orbit satellites such as low Earth orbit satellites greatly compensates for the disadvantage of geostationary Earth orbit satellites. Based on the classical constellation design method, the orthogonal circular orbit constellation is proposed. The design objectives considered here are the following: global Earth coverage by low Earth orbit satellites, the duration of continuously covering one mobile station by one satellite is more than 9.57 min, the access satellite link duration time of the mobile station is more than 4.79 min, and the number of satellites and orbits is to be minimum.</p>\u0000 </div>","PeriodicalId":50289,"journal":{"name":"International Journal of Satellite Communications and Networking","volume":"41 5","pages":"441-459"},"PeriodicalIF":1.7,"publicationDate":"2023-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45063090","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}
Azam Mehboob, Kelvin J. Layton, Gottfried Lechner, William G. Cowley
The nonlinear power amplifier and the analogue output channel filter with nonconstant group delay add nonlinear and linear distortions to the satellite transmitted signal, respectively. Recently, there has been growing interest in using Wiener predistorters, consisting of separate nonlinear and linear components, to compensate for these distortions in the satellite downlinks. The Wiener predistorter has been shown to effectively deal with signal distortions and has lower complexity compared to other state-of-the-art methods. In this paper, we argue that fully compensating the nonconstant group-delay distortion degrades the overall performance of the Wiener predistortion systems. This is primarily due to the increased peak-to-average power ratio of the signal at the output of the linear predistorter. We show that the overall performance of the Wiener predistorter can be improved by undercompensating the group-delay distortion. We propose two optimizations to address the PAPR growth problem and show using simulations that our approach leads to significant improvement in predistortion performance. Using our Wiener predistorter, the total degradation gap to the ideal limiter channel can be reduced to merely 0.34 dB for 64-APSK modulated signals.
{"title":"Wiener predistorter for nonlinear satellite downlinks","authors":"Azam Mehboob, Kelvin J. Layton, Gottfried Lechner, William G. Cowley","doi":"10.1002/sat.1474","DOIUrl":"10.1002/sat.1474","url":null,"abstract":"<p>The nonlinear power amplifier and the analogue output channel filter with nonconstant group delay add nonlinear and linear distortions to the satellite transmitted signal, respectively. Recently, there has been growing interest in using Wiener predistorters, consisting of separate nonlinear and linear components, to compensate for these distortions in the satellite downlinks. The Wiener predistorter has been shown to effectively deal with signal distortions and has lower complexity compared to other state-of-the-art methods. In this paper, we argue that fully compensating the nonconstant group-delay distortion degrades the overall performance of the Wiener predistortion systems. This is primarily due to the increased peak-to-average power ratio of the signal at the output of the linear predistorter. We show that the overall performance of the Wiener predistorter can be improved by undercompensating the group-delay distortion. We propose two optimizations to address the PAPR growth problem and show using simulations that our approach leads to significant improvement in predistortion performance. Using our Wiener predistorter, the total degradation gap to the ideal limiter channel can be reduced to merely 0.34 dB for 64-APSK modulated signals.</p>","PeriodicalId":50289,"journal":{"name":"International Journal of Satellite Communications and Networking","volume":"41 4","pages":"392-405"},"PeriodicalIF":1.7,"publicationDate":"2023-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/sat.1474","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49509740","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}
<p>WHY A NEW STANDARD FOR SATCOM? AND WHY 3RD GENERATION PARTNERSHIP PROJECT (3GPP) HAS DEVELOPED SUCH STANDARD FOR SATCOM?</p><p>With recent moves that have been seen towards the integration of satellite communication in 3GPP eco-system and the emergence of hybrid terrestrial-satellite systems, the following questions arise: What are the roles for satellite communications in 5G system? Why a new standard for Satcoms? And, why was such standard developed in 3rd Generation Partnership Project (3GPP)?</p><p>Ensuring global service continuity, high service reliability and availability are three main challenges for mobile telecommunications technologies. In Recommendation ITU-R M.2083—IMT Vision—Framework and overall objectives of the future development of IMT for 2020 and beyond, on the relationship between IMT-2020 and other access systems, it is recommended that users should be able to <b>access services anywhere</b>, <b>anytime</b>. To achieve this goal, interworking will be necessary among various access technologies, which might include a combination of different fixed, terrestrial and satellite networks. Each component should fulfill its own role, but also should be integrated or interoperable with other components to provide ubiquitous seamless coverage.</p><p>As depicted in Figure 1, prior to 3GPP Release-17, 3GPP networks are natively designed only for Terrestrial based cellular networks. On the other hand, Satellite Networks are based on proprietary technologies. Thereby, only limited interworking between Satcom based Networks and 3GPP cellular networks components is possible. 3GPP work on Non-Terrestrial Network (NTN) and the integration of satellite technology in 3GPP specifications starting from 3GPP Release-17 open a new frontier in 3GPP cellular systems and usher in new paradigms for connected society by adding a satellite component to the 5G system and thereby delivering the promise of an ubiquitous end-to-end ecosystem that can support a myriad of new use cases. Here, “integration” means that the satellite and terrestrial components of the network are able to work together seamlessly to provide coverage continuity to end users. As the 5G design is originally optimized for terrestrial network component a great care has been taken to minimize impacts at UE, NG-RAN and 5GC level while supporting the largest range of satellite network deployment scenarios.</p><p>Beyond 5G, it is expected that 6G networks will natively support both terrestrial and satellite access networks highly integrated at both service and operational level by adopting a design optimized taking into account characteristics of both network components.</p><p>Legacy Satcom systems are characterized by the reliance on industry driven technical specifications leading to proprietary architecture, protocol stack and radio access levels up to the point where basic satellite access network interoperability between different vendors is not granted. Hence the current approach f
技术
{"title":"Guest editorial IJSCN special issue on 3GPP NTN standards for future satellite communications","authors":"Mohamed El Jaafari, Nicolas Chuberre","doi":"10.1002/sat.1472","DOIUrl":"10.1002/sat.1472","url":null,"abstract":"<p>WHY A NEW STANDARD FOR SATCOM? AND WHY 3RD GENERATION PARTNERSHIP PROJECT (3GPP) HAS DEVELOPED SUCH STANDARD FOR SATCOM?</p><p>With recent moves that have been seen towards the integration of satellite communication in 3GPP eco-system and the emergence of hybrid terrestrial-satellite systems, the following questions arise: What are the roles for satellite communications in 5G system? Why a new standard for Satcoms? And, why was such standard developed in 3rd Generation Partnership Project (3GPP)?</p><p>Ensuring global service continuity, high service reliability and availability are three main challenges for mobile telecommunications technologies. In Recommendation ITU-R M.2083—IMT Vision—Framework and overall objectives of the future development of IMT for 2020 and beyond, on the relationship between IMT-2020 and other access systems, it is recommended that users should be able to <b>access services anywhere</b>, <b>anytime</b>. To achieve this goal, interworking will be necessary among various access technologies, which might include a combination of different fixed, terrestrial and satellite networks. Each component should fulfill its own role, but also should be integrated or interoperable with other components to provide ubiquitous seamless coverage.</p><p>As depicted in Figure 1, prior to 3GPP Release-17, 3GPP networks are natively designed only for Terrestrial based cellular networks. On the other hand, Satellite Networks are based on proprietary technologies. Thereby, only limited interworking between Satcom based Networks and 3GPP cellular networks components is possible. 3GPP work on Non-Terrestrial Network (NTN) and the integration of satellite technology in 3GPP specifications starting from 3GPP Release-17 open a new frontier in 3GPP cellular systems and usher in new paradigms for connected society by adding a satellite component to the 5G system and thereby delivering the promise of an ubiquitous end-to-end ecosystem that can support a myriad of new use cases. Here, “integration” means that the satellite and terrestrial components of the network are able to work together seamlessly to provide coverage continuity to end users. As the 5G design is originally optimized for terrestrial network component a great care has been taken to minimize impacts at UE, NG-RAN and 5GC level while supporting the largest range of satellite network deployment scenarios.</p><p>Beyond 5G, it is expected that 6G networks will natively support both terrestrial and satellite access networks highly integrated at both service and operational level by adopting a design optimized taking into account characteristics of both network components.</p><p>Legacy Satcom systems are characterized by the reliance on industry driven technical specifications leading to proprietary architecture, protocol stack and radio access levels up to the point where basic satellite access network interoperability between different vendors is not granted. Hence the current approach f","PeriodicalId":50289,"journal":{"name":"International Journal of Satellite Communications and Networking","volume":"41 3","pages":"217-219"},"PeriodicalIF":1.7,"publicationDate":"2023-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/sat.1472","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48784905","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}
Mohamed El Jaafari, Nicolas Chuberre, Stephane Anjuere, Laurent Combelles
With the recent publication of a set of technical specifications in 3rd Generation Partnership Project (3GPP) related to non-terrestrial network (NTN) enhancements, a global standard for satellite systems is newly defined aiming to support any orbit, any frequency band, and any device. It opens the door for the seamless integration of satellite network component in 5G system and beyond, delivering the promise of a ubiquitous mobile system that can support new use cases. The emergence of hybrid terrestrial-satellite systems is the result of a joint effort between stakeholders of both mobile and satellite industries and is paving the way to new business opportunities. This paper attempts to provide a comprehensive view on this 3GPP NTN standard and what are the next steps.
{"title":"Introduction to the 3GPP-defined NTN standard: A comprehensive view on the 3GPP work on NTN","authors":"Mohamed El Jaafari, Nicolas Chuberre, Stephane Anjuere, Laurent Combelles","doi":"10.1002/sat.1471","DOIUrl":"10.1002/sat.1471","url":null,"abstract":"<div>\u0000 \u0000 <p>With the recent publication of a set of technical specifications in 3rd Generation Partnership Project (3GPP) related to non-terrestrial network (NTN) enhancements, a global standard for satellite systems is newly defined aiming to support any orbit, any frequency band, and any device. It opens the door for the seamless integration of satellite network component in 5G system and beyond, delivering the promise of a ubiquitous mobile system that can support new use cases. The emergence of hybrid terrestrial-satellite systems is the result of a joint effort between stakeholders of both mobile and satellite industries and is paving the way to new business opportunities. This paper attempts to provide a comprehensive view on this 3GPP NTN standard and what are the next steps.</p>\u0000 </div>","PeriodicalId":50289,"journal":{"name":"International Journal of Satellite Communications and Networking","volume":"41 3","pages":"220-238"},"PeriodicalIF":1.7,"publicationDate":"2023-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43894386","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}
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":"41 4","pages":"374-391"},"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":"41 1","pages":"1 - 13"},"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}
<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
{"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":"41 2","pages":"99-101"},"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":"41 3","pages":"276-288"},"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.
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