VSAT networks in the intelsat system

This paper describes how VSAT networks currently operate in the INTELSAT system. Four classes of VSAT networks (data transaction; circuit-switched; data distribution; microterminals) are identified, and it is verified that all of them can operate with INTELSAT satellites. Most VSAT networks in operation on INTELSAT today operate in fractional transponder leases. Fractional transponder capacity estimates are presented for a wide range of scenarios and different INTELSAT satellite series. These estimates clearly show increasing bandwidth utilization efficiencies for newer generations of INTELSAT satellites. Provided that VSAT and hub sizes are appropriately selected, efficiencies are already significant with existing satellites. Two possible ways of increasing the utilization of satellite resources are examined in the paper: demand assignment multiple access (DAMA) and multiple channel-per-carrier (MCPC) techniques. The impact of using DAMA in circuit-switched VSAT networks is quantified.     

VSATs: expert views on future trends

Each of the authors, who comprise a cross section of industry experts from vendor organizations, service providers, research institutions, and international carriers, gives his views on the planned activities and future trends with regard to VSAT (very small aperture terminal) technology, business, and applications, among others. Included in the discussion is the impact of mobile satellite technology on VSAT products and markets; international VSAT applications and ISDN; the influence of OBP satellites; and the use of microterminals in Europe     

A satellite system for CATV

The increasing capacity of CATV systems has generated a demand for more program material than can be economically generated with local facilities. A possible solution is a nationwide satellite distribution system dedicated to CATV which would provide the additional material directly to the CATV head-end. This paper presents a satellite system design that would distribute six TV channels to 10 ft antenna terminals located at the head-end. Since such a system requires thousands of receiving terminals, their cost must be minimized to produce an economically viable system. The system addressed in this paper requires a ground terminal that is comparable to a standard microwave relay terminal in both cost and complexity. The system consists of three satellites, covering the Eastern, Central, and Western portions of the United States. Based on tradeoffs of spectrum availability and low-noise amplifiers, the 12 GHz frequency band has been selected for the satellite to terminal link. The proposed terminal uses a fixed high-efficiency 10 ft antenna with extremely simple but rigid construction. A low-cost tunnel diode amplifier is used for the receiver front end. After the necessary down-conversion, detection of each channel is performed at the standard 70 MHz IF frequency. The required satellites could be launched on an Atlas Centaur launch vehicle using present technology. The satellites would weigh an approximate 1500 Ib and generate 5 kW of dc power.     

基于DVB-RCS和WiMAX的卫星宽带无线接入体系设计

卫星宽带通信已成为目前研究的热点.现有的DVB-RCS卫星无线接入标准以物理层规范为主,尚未构成完整的卫星宽带无线接人体系.本文基于DVB-RCS技术,针对卫星宽带无线接入的需求和特点,结合地面WiMAX宽带无线接入技术,给出了卫星宽带无线接人体系的功能架构设计,并具体分析了各主要功能的设计与实现方法.     

利用安捷伦ADS产生DVB-S数字卫星电视信号--ADS仪表连接应用

在数字卫星电视接收系统的开发过程中,为了验证接收系统的正确性,(即接收系统是否可以正常工作,是否可以正常地播放出图像)需要一个卫星信号源,要求它应该能够产生具有卫星编码的活动图像信息,从而使接收系统工作于符合DVB标准的数字卫星系统中.本文将阐述如何利用安捷伦ADS仿真软件和ESG E4438C矢量信号发生器,产生出带有图像信息的DVB-S数字卫星电视信号.     

Services and supporting architecture of the ESA OBP system

The ESA on-board processing (OBP) satellite system using on-board regeneration and baseband circuit switching has been designed to provide ISDN connectivity and services to users on a Pan-European basis. It is thus seen at its periphery as a 2 Mb/s primary rate access, hence allowing for the interconnection of equipment and terminals compatible with this standard interface. Among the various possible network architectures that the system could support, the business-oriented closed networks look most promising. It has therefore been retained as a prime design driver for OBP system developments. Optionally, connectivity can be offered in an optimized manner to pure data networks, e.g. for LAN-to-LAN interconnection at rates up to 1 Mb/s. In the paper, communication services and networking capabilities offered by the system are briefly reviewed. The internal characteristics of the satellite system allowing for such capabilities are then reviewed and the corresponding performance outlined. The system is shown to be compatible with critical CCITT performance criteria.     

Co‐channel interference cancelation at the user terminal in multibeam satellite systems

We study the applicability of soft interference cancelation in the forward link of multibeam satellite systems with focus on mobile terminals. We adopt a standard currently used in commercial satellite systems as a reference. The multibeam satellite antenna radiation diagram has been generated using a physical optics reflector model while a widely adopted channel model has been used for the land mobile satellite channel. The interference pattern has been derived using a system simulator developed by the European Space Agency. Starting from the analysis of the interference pattern, we study the application of a low‐complexity soft interference cancelation scheme for commercial applications. Our results show that, under realistic conditions, a two‐colors frequency reuse scheme can be employed while guaranteeing service availability across the coverage and keeping the complexity at the user terminals relatively low. Copyright © 2015 John Wiley & Sons, Ltd.     

Performance of Multibeam Packet Satellite Systems with Conflict Free Scheduling

The concept of a multibeam satellite system With on-board processing and memory is studied. In this system multiple slotted ALOHA uplinks carry the traffic to the satellite. Packets are accepted at the satellite, when memory is available, and are routed to their destination zones using a TDM protocol. We present a model which can be used to evaluate a satellite system with conflict-free scheduling, i.e., a system in which several packets can be simultaneously chosen for downlink transmissions, given each earth zone is served by at most one satellite transponder in each slot. We compute the system throughput, packet delays, and buffer overflow probabilities for a general configuration. It is shown that for some configurations the one beam per zone restriction can have a significant effect on the system performance. The presented model can be also used to evaluate satellite systems when this restriction is removed and to evaluate a variety of other satellite systems.     

LTE空中接口在卫星通信中的适用性

目前LTE体制已成熟,在卫星通信系统中应用LTE技术有利于星地一体化网络的发展.移动卫星系统在4G网络中成功应用的一个关键因素是设备和地面系统得到最大的通用性.一种有效的解决这个问题的方法是利用地面空中接口作为卫星空中接口的基础.由于3GPP(The 3rd Generation Partnership Project...     

一种星地一体化路由设计的卫星IP网络

现有大部分支持IP的卫星系统只是提供一个连接地面路由器的物理通道,难以满足宽带接入、多媒体服务以及星地网络一体化等新的需求.为此,提出了一个分组传输和交换均基于IP的GEO卫星系统,并从传输网络和路由结构两方面进行了描述.并针对星上资源紧张的现状,采用了一种地面路由星上交换的新设计思路.通过星上IP交换可实现大量终端间的单跳通信,一个可扩展的集中式IP路由结构可有效减少通过卫星的路由流量,使得通信效率提高的同时,能实现卫星网络与Internet的无缝兼容.     

A new FQPSK modem/radio architecture for PCS and mobile satellitecommunications

A newly developed constant envelope FQPSK modem/radio architecture, which employs a modified double-jump (DJ) filter in the cross-correlated FQPSK system, is proposed for personal communications systems (PCS) and mobile satellite applications. The power efficiency and spectrum efficiency of this system are investigated in a nonlinear amplified (NLA) environment. The bit error rate (BER) performance is evaluated in a noisy Rayleigh fading channel. We demonstrate that with the simplest threshold detectors (binary robust eye diagrams in I and Q channels), this system is 4-7 dB more power efficient than the US digital cellular and Japanese Handyphone standard π/4-QPSK (50%-100% more spectrally efficient than the recently adopted wireless local area network (LAN) standard GFSK and the European standard GMSK). The results indicate that the proposed DJ filtered FQPSK is a power and spectrally efficient modem/radio technique. By selecting different system parameters, this system can be optimized for a wide range of applications in PCS and mobile satellite communications     

Physical layer DVB‐SH performance prediction based on mutual information

Digital Video Broadcasting‐Satellite Handled (DVB‐SH) is a hybrid satellite terrestrial broadcasting standard dedicated to provide video or audio services for handheld terminals. On the satellite part, this standard can make use of interleaving mechanisms to mitigate the effects of the Land Mobile Satellite channel. As a result, these mechanisms enable the in‐time distribution of a codeword over a duration ranging from 100 ms to about 30 s, depending on their parameters. This mechanism significantly improves the error recovery performance of the code; however in the literature, a theoretical evaluation at system level of this improvement is missing. Moreover, carrying out Monte‐Carlo simulations implementing real decoding processes on significant traveled distances is time prohibitive. We propose hereafter a prediction method compatible with fast simulations to quantitatively evaluate the system performance in terms of Rate, Erroneous Second Ratio, and zapping time. This method is based on the computation of the mutual information between emitted and received symbols for QPSK modulation and turbo coding. We demonstrate that our method reaches a prediction precision of the order of 0.1 dB, which is significantly better than two classical prediction methods. Moreover, our solution reduces the simulation time by a factor of 500 compared with Monte‐Carlo. Beyond DVB‐SH application, the presented approach can be applied in a large panel of satellite mobile systems and is completely new for the satellite community. Copyright © 2012 John Wiley & Sons, Ltd.     

一种Inmarsat卫星通信系统下行链路初始同步方法

同步技术是Inmarsat卫星通信系统的关键技术,下行链路初始同步是MES与卫星系统之间建立联系的重要一步。为实现MES快速稳定入网,提出了一种下行链路初始同步的方法。该同步方法已经在移动卫星通信终端上实现,并已商业化应用。应用结果表明,该方法稳定可靠,终端能快速注册入网,可为我国自主研制的卫星系统终端的设计和研究提供参考。     

卫星通信地球站的集中监控系统

卫星地球站监控系统的主要任务是对卫星通信站设备进行监视和控制管理。随着计算机技术、网络技术和远程控制技术的发展,卫星通信地球站向一体化发展,它同时担负着卫星数据传输和卫星站管理监控的双重任务,尤其是对远端站的管理监控。本文总结了以往卫星地面站监控系统优缺点,详细分析了卫星通信地球站集中监控管理系统的工作原理,提出了一套完整的同时针对地球主站和远端站集中监控管理的规划设计和工作流程,并给出了使用效果,旨在为卫星地面站的监控设计和实现提供借鉴思路。     

Performance of DS/CDMA-based equatorial LEO satellite system usingturbo-codes

Improving the bit error rate (BER) performance at low elevation angles is a crucial determining factor for the capacity of any low earth orbit (LEO) satellite system. In previous work, it has been demonstrated that the BER performance of a DS/CDMA-based equatorial LEO satellite system on a downlink can be improved significantly by using satellite diversity. The authors address the issue of improving BER at low elevation angles by using turbo codes     

Satellite communications relay system using a retrodirective space antenna

A system has been developed for relaying messages via a satellite between earth points. In this system, messages transmitted to a satellite modulate a retrodirective antenna. Earth stations receive messages by irradiating the satellite antenna. Methods of modulating the retrodirective array are discussed with emphasis on methods to facilitate communications among several ground stations. There are advantages in spectrum usage and sharing with surface facilities. System design parameters are presented. Minimal power is required in the satellite as compared to the active communications satellites. Extremely high reliability is inherent in the design of the satellite electronic system, which can be made entirely from solid-state components.     

Skyplex: distributed up-link for digital television via satellite

This paper introduces a novel concept of distributed up-link for digital television via satellite. A number of broadcasters situated in different geographical locations can independently have direct access to the satellite for multiplexing and direct-to-home transmission. The system utilises advanced on-board processing techniques for the multiplexing of signals into a single multiprogramme transport stream. The down-link transmission is in accordance with the European standard for digital video broadcasting     

Simulation and analysis of software defined cognitive frequency hopping multi beam satellite system

Traditional multi-beam satellites cannot adapt to the changing traffic because of the fixed bandwidth and cannot adjust dynamically for the traffic load.In the future,the multi-beam broadband satellite system must have great flexibility and can be dynamically adjusted according to the change of the traffic flow.Beam hopping for multi-beam broadband satellite network system has been proposed to improve the traditional multi-beam broadband satellite network system performance,whose principle is to assign different beams to different time slots,rather than the allocation of bandwidth,so that in each time slot,the entire available bandwidth is allocated to each beam,and the time window is periodically applied to the beam selection system ,in the full band hopping mode,the band can be selected optimally in the duration of each beam to meet user transmission bandwidth and delay requirements.With the development of cognitive radio technology,cognitive beam hopping for multi-beam satellite system can further improve the efficiency of spectrum utilization,to meet the growing shortage of spectrum resources,to achieve large-capacity high-bandwidth broadband satellite network system,and to support the rising user service capacity and the transmission efficiency of user services under different load conditions.In addition,software definition technology is also used in satellite networks,which could achieve effective management of satellite resources to improve the utilization of satellite resources.In this paper,the principle of software-defined cognitive hopping multi-beam broadband satellite network system is discussed.The spectrum utilization efficiency and throughput are analyzed,which can be used as a reference for broadband satellite network system design.     

Introduction to the 3GPP-defined NTN standard: A comprehensive view on the 3GPP work on NTN

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.     

微纳卫星组网星间链路设计及关键技术分析

微纳卫星组网应用可大幅度提高航天装备的能力,较单颗大卫星具有明显的优势。首先,介绍了国内外微纳卫星组网的研究情况,以组网侦察应用为例分析了星间测量与通信链路的技术需求,并进行了系统架构和体制设计;其次,在星座设计基础上开展系统仿真,并提出了一体化设备实现方案;最后,分析了微纳卫星组网系统中几项重要的关键技术及其解决方案,对系统的设计和工程实现具有参考价值。