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1.
DVB-RCS卫星互动网络,应用前景广阔。DVB-RCS标准是为了在单向的卫星广播网络中(DVB-S)实现双向互动网络而采纳的一系列技术规范,但标准中仅规定了空中接口,没有提到如何实现一个网络的MAC接入层。卫星网络的实现结构是其MAC接入层协议的重要组成部分。本文设计了一个DVB-RCS卫星互动网络的网络结构,重点解释了它的多址接入方式和资源分配方式,最后描述了它的入网过程。 相似文献
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Over the past several years, a number of new satellite systems have been proposed to provide high-speed Internet and multimedia services to businesses and home users. These proposals have been driven by the desire of network operators to reach end users that do not have cost effective access to other alternatives such as fiber, DSL, and cable, and by the availability of new spectrum (Ka-band) for use by new satellite services. The proposed systems generally employ multiple high-power spot beams, an onboard fast packet switch, and a demand-assigned multiple access scheme to provision IP-based services. In this article we concentrate on a geosynchronous satellite system where packet transport and switching within the satellite system are based on ATM. We describe an IP/ATM interworking and IP routing architecture that is driven by three main requirements: (1) the ability to support ATM SVCs between hundreds of thousands of satellite terminals by a single ATM switch located onboard; (2) a scalable IP routing architecture that does not result in large volumes of routing traffic to be transported over the satellite; and (3) the ability to segment the satellite terminals for routing and administrative control by ISPs and enterprise networks 相似文献
3.
介绍了VSAT数据网原理、卫星通信系统宽带化的发展趋势及DVB-RCS开放标准。通过介绍基于DVB-RCS的VSAT宽带卫星通信系统在工程中的应用实例,其中包括系统业务与特点,以及各子系统的基本配置等,可以得出,随着网络和业务的宽带化,VSAT卫星通信系统正在从传统的窄带向宽带系统转变。在现有技术中,基于DVB-RCS... 相似文献
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Skinnemoen H. Leirvik R. Hetland J. Fanebust H. Paxal V. 《Selected Areas in Communications, IEEE Journal on》2004,22(3):508-517
Following decades of closed proprietary satellite systems, the open European Telecommunications Standards Institute (ETSI) standard for interactive broadband satellite services digital video broadcast-return channel via satellite (DVB-RCS) was approved and published in March 2000. Considerable work has been performed by satellite operators, manufacturers and others, in order to deploy DVB-RCS systems for commercial Internet protocol (IP) services. Their efforts have not only resulted in several DVB-RCS systems now in commercial operation, but also in a common focus on interoperability between equipment from different manufacturers through the SatLabs group, working under the auspices of the European Space Agency (ESA). In addition to the open standard aspect, success for DVB-RCS depends on equipment cost and bandwidth efficiency offered by the system, as discussed in this paper. Equipment cost is important as it represents the initial investment for the operator and the final users, while the cost of usage depends on the efficiency, and will, in the long term, be the dominating cost factor. The DVB-RCS specification opens up for a wide range of radio resource management (RRM) implementation possibilities and the RRM plays a key role in optimizing the efficiency of the system for the targeted IP services. This paper presents the main features of a complete DVB-RCS system, the Nera SatLink system, hereafter only referred to as the SatLink system, and offers measurement results and experience from DVB-RCS installations. Critical parts of the system are highlighted, and focus is given to the objectives for current optimization of the system. 相似文献
5.
QoS provisioning in GEO satellite with onboard processing using predictor algorithms 总被引:1,自引:0,他引:1
Recently, IP satellite networks have attracted considerable interest as a technology to deliver high-bandwidth IP-based multimedia services to nationwide areas. In particular, IP satellite networks seem to be one of the most promising technologies for connecting users in rural areas, where a wired high-speed network (e.g., xDSL) is not foreseen to be used. However, one of the main problems arising here is to guarantee specific quality of service constraints in order to have good performance for each traffic class. Among various QoS approaches used in the Internet, recently the DiffServ technique has become the most promising solution, mainly for its scalability with respect to the IntServ approach. Moreover, in satellite communication systems, DiffServ computational capabilities are placed at the edge points, reducing the implementation complexity of the satellite onboard equipment. This article deals with the problem of QoS provisioning for packet traffic by considering some resource allocation schemes, including bandwidth allocation techniques and priority-driven onboard switching algorithms. As to the first aim, the proposed technique takes advantage of proper statistical traffic modeling to predict future bandwidth requests. This approach takes into consideration DiffServ-based traffic management to guarantee QoS priority among different users. Moreover, the satellite onboard switching problem has been addressed by considering a suitable implementation of the DiffServ policy based on a cellular neural network. 相似文献
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VoIP over DVB-RCS with QoS and bandwidth on demand 总被引:1,自引:0,他引:1
《Wireless Communications, IEEE》2005,12(5):46-53
Motivated by the need for compliance/interoperability above the satellite-specific layers, this article proposes a consolidated approach for voice over IP over satellite networks based on the ETSI DVB-RCS standard. Voice communication is a real-time service that needs priority over other services in IP environments with limited bandwidth, such as IP satellite networks. Bandwidth utilization in such networks needs to be optimized in order to reduce service costs, and this requires the use of dynamic bandwidth allocation schemes. This article therefore addresses the role of bandwidth on demand in the optimization of bandwidth allocation for VoIP and assesses the impact of BoD mechanisms on voice quality. The trade-off between voice quality and bandwidth efficiency is investigated under different DVB-RCS-specific capacity request/allocation strategies, and it is demonstrated that DVB-RCS provides an efficient platform for integrated support for a variety of VoIP applications over satellite. The main contribution of this article consists of the identification of the mechanisms capable of responding to the key challenges raised by the VoIP application in the satellite environment. 相似文献
8.
Jamalipour A. 《Proceedings of the IEEE. Institute of Electrical and Electronics Engineers》2001,89(1):88-104
Next-generation broadband satellite networks are being developed to carry bursty Internet and multimedia traffic in addition to the traditional circuit-switched traffic (mainly voice) on a global basis. These satellites provide direct network access for personal applications as well as interconnectivity to the terrestrial remote network segments. The main requirement in success of these networks is that they should be able to transmit high data rate traffic with prescribed quality of service (QoS). Thus, the broadband satellite network has no choice other than the rise of ATM technology and to be optimized for Internet-based traffic. ATM is the promising technology for supporting high-speed data transfer potentially suitable for all varieties of private and public telecommunications networks. IP, on the other hand is the fast-growing Internet layer protocol that is applicable over any data link layer Internet-based applications are the emerging source of traffic in the future wireless networks and broadband satellite networks should consider Internet as the primary service. In this paper, we discuss the traditional ATM and wireless ATM networks and explain the characteristics of the wireless IP networks. The paper then uses those concepts in defining the criteria for the broadband satellite networks such as the QoS and traffic management. Application of the broadband satellite networks is also proposed 相似文献
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Onboard switching for ATM via satellite 总被引:3,自引:0,他引:3
This article presents an architecture for onboard ATM switching. The constraints of the space environment and the associated delays (especially with geostationary satellites) create often conflicting requirements for the implementation of ATM via satellite. These requirements must be considered when designing onboard equipment. The article suggests that the use of MF-TDMA framing and of physical-layer scheduling as a preswitching stage allows for the use of standard switch fabrics onboard with additional fault tolerance and buffer mechanisms. The details of the scheduler and of the RF front end, including demodulation and demultiplexing, are presented as well as suitable switch fabrics and their performance/implementation impact. ATM is now widely considered the delivery medium for the broadband services of the future. This fact has also attracted the attention of the satellite community. Current satellite ATM trials have concentrated on trunking applications using available broadcast satellites. However, the US FCC filings for Ka band satellites, as well as Canadian W and European initiatives, have focused on a new generation of digital regenerative multibeam onboard processing satellites 相似文献
11.
TCP/IP enhancements for satellite networks 总被引:7,自引:0,他引:7
With the emerging market for high-mobility remote access broadband services, satellite networks are becoming increasingly popular. Although the ubiquitous TCP/IP protocol is widely used to provide reliable data delivery in terrestrial networks, it faces many challenges in satellite environments. These stem from the inherent features of satellite channels, such as large delays, increased error rates, and bandwidth asymmetry. To address these concerns, a variety of solutions have been proposed. These include direct TCP enhancements to better tune the TCP/IP stack and additional selective acknowledgment mechanisms. Other proposals use advanced interworking to reduce sensitivity to various channel features. Examples include multiple TCP sessions, link-layer interworking, and ACK control schemes. Improving onboard satellite features (buffer management, flow control) can also provide benefits for TCP/IP transport. The objective of this article is to present the various solutions and discuss their possible trade-offs. Overall, there exists a rich set of alternatives to meet the challenges in this important arena 相似文献
12.
High-speed satellite mobile communications: technologies and challenges 总被引:12,自引:0,他引:12
Ibnkahla M. Rahman Q.M. Sulyman A.I. Al-Asady H.A. Jun Yuan Safwat A. 《Proceedings of the IEEE. Institute of Electrical and Electronics Engineers》2004,92(2):312-339
Central features of future 4G mobile communication systems are high-speed data transmission (up to 1 Gb/s) and interactive multimedia services. For effective delivery of these services, the network must satisfy some stringent QoS metrics, defined typically in terms of maximum delay and/or minimum throughput. Mobile satellite systems will be fully integrated with the terrestrial cellular systems to provide ubiquitous global coverage to diverse users. The challenges for future broadband satellite systems, therefore, lie in the proper deployment of state-of-the-art satellite technologies to ensure seamless integration of the satellite networks into the cellular systems and its QoS frameworks, while achieving, as far as possible, efficient use of satellite link resources. The paper presents an overview of future high-speed satellite mobile communication systems, the technologies deployed or planned for deployment, and the challenges. Focusing in particular on nonlinear downlink channel behavior, shadowing and multipath fading, various physical channel models for characterizing the mobile satellite systems are presented. The most prominent technologies used in the physical layer, such as coding and modulation schemes, multiple-access techniques, diversity combining, etc., are then discussed in the context of satellite systems. High-speed and QoS-specific technologies, such as onboard processing and switching, mobility and resource management, IP routing and cross-layer designs, employed in the satellite systems are also discussed. 相似文献
13.
PSTN(公用交换电话网)将逐渐向分组化和宽带化的方向演变,在演变过程中,PSTN的网络简化与采用多业务交换平台,将起重要的作用。文中对这两方面作一简要介绍,说明网络简化的目标和应考虑的实际问题,包括远端交换模块和转接局、网关局的合理配置,以及大容量交换系统的选用。并以E-Cube多媒体交换系统为例,说明窄带STM(同步传送模式)和宽带ATM(异步传送模式)的综合交换,窄带业务与IP的结合,以及ATM与IP的结──MPLS(多协议标记交换)。这种多业务交换平台用在ATM/IP骨干网的边缘级,将有利于PSTN与各种新型网络互通。 相似文献
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Yunhui Zhou Fuchun Sun Bo Zhang 《International Journal of Satellite Communications and Networking》2007,25(6):603-617
The rapid advance of communication and satellite technology pushes broadband satellite networks to carry on multimedia traffic. However, the function of onboard routing cannot be provided in existing satellite networks with inter‐satellite links, and quality of service (QoS) of satellite networks cannot be reliably guaranteed because of great difficulties in processing of long distance‐dependent traffic. In this paper, a two‐layered low‐Earth orbit and medium‐Earth orbit satellite network (LMSN) is presented. A novel hierarchical and distributed QoS routing protocol (HDRP) is investigated, and an adaptive bandwidth‐constrained minimum‐delay path algorithm is developed to calculate routing tables efficiently using the QoS metric information composed of delays and bandwidth. The performance of LMSN and HDRP is also evaluated through simulations and theoretical analysis. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
16.
文章简单回顾窄带卫星网络,介绍利用宽带卫星链路接入因特网的特点和好处,讨论卫星与陆地网络的互联、卫星链路上的TCP/IP协议和卫星网络的移动管理等关键技术问题。 相似文献
17.
Hermann Bischl Markus Werner A. Dreher L. Richard E. Lutz J. Bosti
H. Brandt Petia Todorova F. Krepel M. Emmelmann 《International Journal of Satellite Communications and Networking》2005,23(1):1-32
Future broadband satellite networks for multimedia will be seamlessly integrated into terrestrial broadband networks which often use asynchronous transfer mode (ATM) and recently also the less complex multi protocol label switching (MPLS) technique as transmission and switching protocol. In light of this, future broadband satellite networks may adopt the ATM transmission scheme and implement ATM or ATM‐like switches on board the satellites. However, as compared to communication in fixed networks, satellite communication is characterized by special constraints (e.g. signal delay, channel quality, dynamic network topology) that require novel ATM‐based communication technology for satellite systems. This paper presents results from the ATM‐Sat project that aims to complete this technically challenging and important R&D task in the cooperation between DLR, Fraunhofer Gesellschaft and Tesat‐Spacecom. In brief the following aspects have been addressed in the ATM‐Sat project:
- development of the concept and communication technology for a multimedia satellite system with,
- non‐geostationary orbit (NGSO) satellites;
- inter satellite links (ISLs);
- on‐board ATM switching;
- fixed and mobile terminals;
- verification of the developed communication technology with a demonstrator.
18.
当前,大部分支持IP的卫星系统只是提供了一个连接地面路由器的物理通道,难以满足带宽接入、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,采用三层路由交换的组网方案,实现了同一交换域内用户信息的链路层快速转发,以及不同交换域间用户IP信息的网络层路由交换处理.最后,研究了最简单的RIP路由协议在此GEO卫星网络中的适应性,利用OPNET仿真软件对其进行了建模仿真及结果分析. 相似文献
19.
一种基于复指数调制精确重构滤波的宽带星载数字信道化器 总被引:2,自引:0,他引:2
信道化技术是下一代宽带卫星通信系统中星载交换的关键技术之一。运用该技术,提取宽带卫星上行信号中的各窄带信号,然后经过变频、基带信号处理、交换等处理,最后综合成宽带下行信号,进入卫星下行链路。该文针对宽带卫星通信系统,提出一种基于复指数调制精确重构滤波器组的新型宽带星载数字信道化器。该信道化器既适合均匀带宽交换、又适合非均匀带宽交换的星载信道化器。数值实验表明,该新型信道化器具有较强的灵活性和可扩展性,克服了已有信道化技术只适合均匀带宽星载交换的局限,同时对信噪比和数据存储量有较大的改进和提高。 相似文献
20.
基于可靠UDP的卫星IP网关设计 总被引:1,自引:0,他引:1
TCP是面向连接的可靠点到点协议,但是由于卫星网络中典型的长延时、高误码率以及非对称带宽的特点,导致TCP通过宽带卫星网络时,信道利用率非常低。可靠UDP协议基于标准UDP协议并在应用中增加窗口、应答和重传算法来实现。网关采用该协议将TCP连接分段,在应用中明显地改善了TCP在宽带卫星信道上传输的性能,增加TCP的信道利用率。 相似文献