Digital Video Broadcasting-Return Channel Via Satellite Research Articles

Novel Resource Allocation Technique for DVB-RCS Compliant Satellite Terminals

Satellite communication is advantageous for several reasons such as broad coverage, small installation time of remote user sites, and network services in inhospitable terrains, where installing terrestrial infrastructure is costly. With the advent of broadband multimedia satellites such as Ku and Ka band satellites, multimedia services to the satellite terminals are gaining momentum. Digital Video Broadcast Return Channel via Satellite (DVB-RCS) is an open standard developed by ETSI which has further standardized, commercialized and solved the problem of inter-operability of Ku Band satellite terminals. Satellite bandwidth is scarce therefore treated as precious resource. In the present paper, authors aim to develop and realize the resource allocation techniques in return link channel for DVB-RCS compliant satellite terminals. The paper provides method for giving preference to real time application in terms of early processing of allocation request generated against the real time traffic to reduce delay and also provides method to avoid parallel connection arises due to transmission of terminal on more than one frequency at a time. Authors have realised DVB-RCS resource allocation technique and have given simulation results.

Implementation of E-education in Africa via space digital video broadcasting system

This paper introduces an advanced E-education provision via space systems for Africa or any other regions in remote dispersed communities, such as rural, mining, agriculture, surveying, construction, tourism, military and etc. Based on the specific needs and requirements E-education implies significant broadband applications, interconnectivity, and timely and quality-assured content delivery of service. The E-education solutions of distance learning and training for remote and rural areas, which are beyond range of terrestrial and short distance wireless cellular facilities, cannot provide broadband access without space-enabled communication solutions, such as satellite constellations and Stratospheric Platform Systems (SPS) or High Altitude Platforms (HAP). This paper also discusses the integration challenges that are presented by combining space solutions for implementation E-education and learning in rural and mobile environments. Configuration of in-house development of all segments, installation of the scale-down Digital Video Broadcasting-Return Channel via Satellite (DVB-RCS) Hub (Gateway), Ground Network and Very Small Aperture Terminal (VSAT), known as Fixed Interactive Terminals (FIT), for E-education, distance learning and staff training initiative in Africa are described.

위성 통신에서 Cross-layer 기반 PEP 성능 평가

위성 통신은 넓은 지역에 통신 서비스를 제공하는 광역 네트워크이다. 하지만, 위성 통신은 대역폭이 제한되고 매우 긴 전파 지연 시간과 높은 BER(Bit Error Rate)로 인해 위성 통신을 고려하지 않은 TCP의 성능이 저하 된다. 본 논문에서는 위성 통신에서의 TCP 성능을 향상시키기 위해 DVB-RCS(Digital Video Broadcasting-Return Channel via Satellite) 네트워크 환경을 고려한 cross-layer 기반 PEP(Performance Enhancing Proxy) 기술을 제안한다. 제안하는 프로토콜은 TCP와 링크 계층 간 위성 자원 할당 정보를 정보 교환을 통해 최적의 TCP CWND(Congestion Window)를 설정한다. 제안한 프로토콜의 성능 평가를 위해 리눅스 기반의 PEP 테스트 베드를 구현하였다. 성능 평가 결과 다양한 BER에서 제안한 프로토콜은 위성 자원 할당 정보를 이용하여 최적의 TCP CWND 크기를 설정하기 때문에 단일 및 다중 세션 환경에서 기존 TCP 보다 제안한 프로토콜이 더 좋은 성능을 보여준다는 것을 확인할 수 있었다. Satellite communication is a wide area network (WAN) which provides communication service worldwide. However, the performance of TCP can be seriously degraded in the satellite networks due to limited bandwidth, long round-trip time (RTT) and high bit error rate (BER) over satellite links. In order to improve the performance of TCP, this paper proposes cross-layer Performance Enhancing Proxy (PEP) in digital video broadcasting-return channel via satellite (DVB-RCS) networks. The proposed protocol sets TCP Congestion Window (CWND) size by using satellite resource allocation information exchanged between TCP and the link-layer. we implement PEP testbed based on Linux to evaluate the performance of the proposed protocol. The simulation results show that the proposed protocol performs better than standard TCP both in single and multiple sessions in variant BER, because the proposed protocol sets TCP CWND size by using satellite resource allocation.

DVB-RCS 네트워크에서 Cross-layer 및 네트워크 코딩 기반 PEP 연구

본 논문에서는 DVB-RCS 네트워크에서 cross-layer와 네트워크 코딩 기반 PEP 기술을 제안한다. 제안한 PEP 기술에서는 TCP와 링크 단 간 위성 자원 할당 정보 교환을 제공할 수 있는 cross-layer 정보 교환 기법을 제안하고, 할당된 위성 자원 정보와 NC-R (Network-Coded Redundancy) 패킷 전송률에 의한 TCP 혼잡제어윈도우 튜닝 기법을 제안한다. 시뮬레이션 결과 제안한 PEP 기술을 사용하면 TCP에서 사용가능 한 자원을 조사하기 위한 지연 없이 바로 최대 이용 가능한 TCP 혼잡제어윈도우 값을 사용할 수 있는 것을 살펴 볼 수 있었다. 또한 제안한 PEP 기법에서는 TCP 혼잡제어윈도우 튜닝 기법과 NC-R 패킷 전송을 통하여 패킷 손실이 발생할 수 있는 이동형 단말 환경에서도 불필요한 위성 자원 사용 없이 TCP 데이터 처리율을 향상 할 수 있는 것을 볼 수 있었다.

Constellation Rotation for DVB Multiple Access Channels With Raptor Coding

In this paper we investigate a technique for increasing the capacity of a Digital Video Broadcasting-Return Channel via Satellite (DVB-RCS) system. In our previous work, we proposed a scheme consisting in adding a non-orthogonal interfering source to a DVB-RCS channel carrying data from an existing source. The inclusion of the new source does not cause bandwidth increase. The secondary source uses Raptor code. The destination will use successive decoding. It decodes the interfering source first, and after its removal, decodes the main source. In this paper, we generalize our work to allow possibility of decoding either the secondary source data (as in our previous work) or the main source data first. We investigate the performance and delay for each decoding scheme. Since the channels are non-orthogonal, it is possible that for some power allocation scenarios constellation points get erased. To address this problem, we use constellation rotation. The constellation map of the secondary source is rotated to increase the average distance between the points in the constellation resulting from the superposition of the main and interfering sources' constellations. Finally, we determine the optimum constellation rotation angle for the interfering source analytically and confirm it with simulations.

Signal-to-Noise Ratio Estimation Algorithm for Advanced DVB-RCS Systems

This paper presents a signal-to-noise ratio (SNR) estimation algorithm for advanced Digital Video Broadcasting-Return Channel via Satellite (DVB-RCS) systems using adaptive coding and modulation (ACM) in the reverse link of broadband satellite systems. Due to the absence of a repetitive pilot symbol structure, SNR estimation has to be performed using the fixed symbol preamble data. Moreover, sporadic nature of data traffic on the return link causes variation in interference level from slot to slot and, therefore, the estimation has to be done within one traffic slot duration. Hence, it becomes necessary to use a combination of data-aided (DA) and decision-directed (DD) algorithms so as to make use of traffic data. A non-data-aided (NDA) estimator that was previously proposed by the authors for binary phase shift keying (BPSK) and QPSK schemes is extended to 8-PSK in a decision directed manner. This estimator shows improved performance over existing estimators. The inherent bias of DD approach at low values of SNR is reduced by using a hybrid approach, i.e., using the proposed estimator at moderate/high values of SNR and the moments-based estimator ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">M</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">M</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> ) at low values of SNR. Overall improved performance of the proposed hybrid estimator, in terms of accuracy and complexity, makes it an attractive choice for implementing ACM in advanced DVB-RCS systems.

Signal-to-noise ratio estimation algorithm for adaptive coding and modulation in advanced digital video broadcasting–radar cross section satellite systems

This paper presents a signal-to-noise ratio (SNR) estimation algorithm for advanced digital video broadcasting- return channel via satellite (DVB-RCS) systems using adaptive coding and modulation (ACM). Due to the absence of a repetitive pilot symbol structure, SNR estimation has to be performed using the fixed symbol preamble data. Moreover, sporadic nature of data traffic on the return link causes variation in interference level from slot to slot and, therefore, the estimation has to be done within one traffic slot duration. Hence, it becomes necessary to use a combination of data-aided and decision-directed (DD) algorithms so as to make use of traffic data. A non-data-aided estimator that was previously proposed by the authors for binary and quadrature phase shift keying schemes is extended to 8-PSK in a decision directed manner. The inherent bias of DD approach at low values of SNR is reduced by using a hybrid approach, that is, using the proposed estimator at moderate/high values of SNR and the moments-based estimator (M2M4) at low values of SNR. Overall improved performance of the proposed hybrid estimator, in terms of accuracy and complexity, makes it an attractive choice for implementing ACM in advanced DVB-RCS systems.

DVB-RCS Next Generation을 위한 Third-dimension Turbo Code 분석

차세대 무선통신에서는 현재 서비스 되고 있는 성능보다 높은 BER(Bit Error Rate)의 성능을 요구한다. 기존의 DVB-RCS(Digital Video Broadcasting - Return Channel via Satellite)에서 사용중인 이진 터보 코드(Double binary Turbo code)는 높은 SNR(에서 오류마루 현상이 발생하여 차세대 무선통신에서 사용하기가 어려움이 있다. 따라서 본 논문에서는 DVB-RCS NG에 적합한 부호화 방식으로 3D-터보 코드(Tthird-dimension Turbo code)의 부복호화기의 구조를 분석하고 성능분석 하였다. 3D-터보 코드는 기존의 DVB-RCS 방식에 rate-1인 post-encoder를 첨가시켜 오류마루 현상을 보완한 부호화기이다. 3D-터보 코드는 post-encoder의 형태, 인터리빙 기법, <TEX>${\lambda}$</TEX>값의 변화에 따라 성능이 달라지므로 본 논문에서는 각 파라메타에 대한 최적의 값을 제시하였다. 전체적으로 3D-터보 코드가 기존의 DVB-RCS 터보 코드에 비해 성능이 우수하고 기존의 문제점인 오류마루 현상을 해결할 수 있음을 알 수 있다. The next generation wireless communication systems are required high BER performance better than present performance. Double binary Turbo code have error floor at high SNR, so it cannot be used in next generation wireless communication system. Therefore, many methods are proposed for overcome error floor at DVB-RCS NG(next generation). In this paper, we analysis structure of third-dimension Turbo code(3D-turbo code). 3D-Turbo code overcomes error flow by additive post-encoder in conventional DVB-RCS Turbo code. Performance of 3D-Turbo code is changed by post-encoder form, interleaving method, value of <TEX>${\lambda}$</TEX>. So we are simulated by those parameter and proposed optimal form. By a result, performance of 3D-Turbo is better than conventional DVB-RCS Turbo code and it overcome error floor of conventional DVB-RCS Turbo code.

Medium access control scheme for supporting user mobility in digital video broadcasting-return channel via satellite/satellite second generation – general architecture and functionalities

This study aims at summarising the work done in the SatNEx project for the development and the performance evaluation of a new access scheme for multimedia data transmissions in digital video broadcasting-return channel via satellite (DVB-RCS)/satellite second generation (S2), applied to a mobile environment. The work has been stimulating because, as far as the authors know, this research topic has not yet been fully addressed in the literature. The authors started thinking about a realistic scenario of mobility, where novel services could be offered; having defined the scenario, the authors developed a satellite access scheme suitable for transmission control protocol (TCP) sessions and video streams in mobility. In this study, the authors present the reference architecture, the access scheme, the choice of the most suitable transmission parameters and the simulation results that are obtained when transmitting the two different types of data.

Linear quadratic control of service rate allocation in a satellite network

The real-time control of multiple queues handling traffic of different nature is obtaining increasing relevance in both the uplink and downlink of wireless telecommunication networks, characterised by the presence of a central access point. Such is the case of satellite networks, with either on-board processing or double-hop configuration, besides a number of terrestrial local and metropolitan wireless networks. Given a certain amount of available bandwidth, the problem is that of deciding, within a certain time frame, the allocation of bandwidth partitions for each traffic queue, whose packets are awaiting transmission; eventually, this determines the transmission rates to be passed to the scheduler and to the physical layer adaptive coding and modulation devices. In a satellite network, where this task is accomplished by a master station, residing at the access point, it is possible to take such decisions by means of a centralised controller, based on real-time instantaneous (in the downstream direction) or delayed (in the upstream) information on the queues' state. The study derives a control law to be used in this task, by adopting an approach based on optimal linear quadratic regulation. Both cases of un-delayed and delayed information are considered. The control laws are tested in a geo-stationary satellite scenario of digital video broadcasting ' return channel via satellite (DVB-RCS), and the queues are considered at the medium access control level. Simulation results under real-traffic traces are also presented to highlight the effectiveness of the control and to compare alternative solutions.

Suitability of DAMA and Contention-Based Satellite Access Schemes for TCP Traffic in Mobile DVB-RCS

The problem of optimizing access and bandwidth sharing among transmission control protocol (TCP) connections in the mobile digital video broadcasting return channel via satellite (DVB-RCS) is tackled in this paper. After sketching the general system architecture, we explicitly deal with the dynamic assignment of bandwidth to TCP connections on the return link, which is accomplished by a network control center (NCC) placed onboard the satellite. Mobile users access the satellite in multifrequency time-division multiple access (MF-TDMA), whereas they receive data from the NCC in time-division multiplexing (TDM). Two different techniques, based on deterministic and random access, are compared in terms of bandwidth usage and average completion time per connection, when the mobile user acts as both server and client. In the server case, to increase the TCP throughput, both packet-level forward error correction (FEC) on data sent by mobile users and a duplicated and delayed acknowledgment technique for TCP acknowledgment traffic from the NCC to the mobile users are applied. An analysis of the packet losses and a simulation campaign of file transfers by employing a realistic channel model has been carried out. The results of the analysis show the convenience of adopting a technique, in addition to the optimal data redundancy in different cases, such as the server or client role of users, their willingness to pay, the file size, and the environment type.

Performance evaluation of TCP‐based applications over DVB‐RCS DAMA schemes

AbstractTransmission Control Protocol (TCP) performance over Digital Video Broadcasting—Return Channel via Satellite (DVB‐RCS) standard is greatly affected by the total delay, which is mainly due to two components, propagation delay and access delay. Both are significant because they are dependent on the long propagation path of the satellite link. The former is intrinsic and due to radio wave propagation over the satellite channel for both TCP packets and acknowledgements. It is regulated by the control loop that governs TCP. The latter is due to the control loop that governs the demand assignment multiple access (DAMA) signalling exchange between satellite terminals and the network control center, necessary to manage return link resources. DAMA is adopted in DVB‐RCS standard to achieve flexible and efficient use of the shared resources. Therefore, performance of TCP over DVB‐RCS may degrade due to the exploitation of two nested control loops also depending on both the selected DAMA algorithm and the traffic profile.This paper analyses the impact of basic DAMA implementation on TCP‐based applications over a DVB‐RCS link for a large set of study cases. To provide a detailed overview of TCP performance in DVB‐RCS environment, the analysis includes both theoretical approach and simulation campaign. Copyright © 2009 John Wiley &amp; Sons, Ltd.

Analysis of QoS for DVB‐RCS‐based IP network

PurposeThe internet has been used to transport data in the form of packet. Multimedia applications including voice and video are being sent using the internet. In the past, the internet did not support any kind of sophisticated quality of service (QoS) mechanism. Although the type of service (ToS) field in the internet protocol (IP) header has been present and allowed the differentiated treatment of packets, it was never really used on a large‐scale. IP applications have been mostly used on terrestrial networks so far. This paper aims to describe the architecture of a DVB‐RCS based satellite network supporting interactive and multimedia applications.Design/methodology/apporachThe use of TCP/IP has made it possible to have two way communication using open standard satellite networks based on digital video broadcast return channel via satellite (DVB‐RCS). The voice and video are sensitive to delay and jitter so bandwidth must be guaranteed while transporting it. With the extensive use of IP for carrying voice and video, there is a need to add QoS functionality in satellite networks. The performance of data transfer using voice and video with reference to QoS parameters in satellite network is analyzed in this paper.FindingsThe results show that satellite networks based on DVB‐RCS can carry voice and video traffic and offer good quality of service in terms of packet loss and jitter but are poor in quality in terms of packet delay.Originality/valueThis paper describes the architecture of a DVB‐RCS based satellite network supporting interactive and multimedia applications.

IPv6 networks over DVB‐RCS satellite systems

AbstractSatellite plays an important role in global information infrastructure (GII) and next generation networks (NGNs). Similarly, satellite communication systems have great advantages to support IPv6 (Internet Protocol version 6) networks as a technology that allows universal access to broadband e‐services (audio, video, VPN, etc.). In the context of DVB‐S2 (digital video broadcast‐satellite) and DVB‐RCS (digital video broadcast‐return channel via satellite) standards, this paper presents the current SatSix project (satellite‐based communications systems within IPv6 networks) within the European 6th Framework Programme, which is implementing innovative concepts and effective solutions (in relation with the economical cost) for broadband satellite systems and services using the technology presented above. This project is promoting the introduction of the IPv6 protocol into satellite‐based communication systems.Moreover, through SatSix, the industry is addressing the next generation Internet, IPv6. It also enhances its competitive position in satellite broadband multimedia systems by exploiting the common components defined by the European DVB‐S2 and DVB‐RCS satellite broadband standards. Copyright © 2007 John Wiley &amp; Sons, Ltd.

A Real-Time Algorithm for Timeslot Assignment in ISM System with DVB-RCS

This paper considers a timeslot assignment problem in an interactive satellite multimedia (ISM) system with digital video broadcast-return channel via satellite (DVB-RCS). The timeslot assignment problem is formulated as a binary integer programming to maximize the overall weighted throughput and is shown to be NP-hard. Thus, three real-time heuristic algorithms including ratio-based, packet-size (PS)-based, and transmission gain (TG)-based are derived, and some computational experiments are made. Considering the results, the ratio-based heuristic algorithm is demonstrated to be the most effective and efficient. We propose adapting the ratio-based heuristic algorithm to the timeslot assignment problem to greatly improve the ISM system utilization.

Effective Admission Policy for Multimedia Traffic Connections over Satellite DVB-RCS Network

Thanks to the great possibilities of providing different types of telecommunication traffic to a large geographical area, satellite networks are expected to be an essential component of the next-generation internet. As a result, issues concerning the designing and testing of efficient connection-admission-control (CAC) strategies in order to increase the quality of service (QoS) for multimedia traffic sources, are attractive and at the cutting edge of research. This paper investigates the potential strengths of a generic digital-video-broadcasting return-channel-via-satellite (DVB-RCS) system architecture, proposing a new CAC algorithm with the aim of efficiently managing real-time multimedia video sources, both with constant and high variable data rate transmission; moreover, the proposed admission strategy is compared with a well-known iterative CAC mainly designed for the managing of real-time bursty traffic sources in order to demonstrate that the new algorithm is also well suited for those traffic sources. Performance analysis shows that, both algorithms guarantee the agreed QoS to real-time bursty connections that are more sensitive to delay jitter; however, our proposed algorithm can also manage interactive real-time multimedia traffic sources in high load and mixed traffic conditions.

An Integrated Medium Access Control and Traffic Management Architecture for DVB-RCS SkyplexNet Satellite Systems

The growing development of standard Internet services and the emerging exploitation of several broadband multimedia contents disclosing in the last years, significantly promoted scenarios where Satellite Networks can play key roles. Several satellite networks are currently implemented according to the Digital Video Broadcasting-Return Channel via Satellite (DVB-RCS) standard, assuming to operate with a transparent satellite and an hub-centric (star) network topology. The present work addresses the SkyplexNet (SKN) system: an advanced Broadband Satellite Network for meshed connectivity developed by Alenia Spazio, within the framework of ESA Artes 3 --- Line 1 Program, according to the DVB-RCS standard with duly extensions for the on-Board multiplexing capability of the Skyplex Units currently embarked on HotBird VI and W3A satellites. In this paper an architecture design study aiming at integrating the Medium Access Control (MAC) and Traffic Management (TM) functionality in a DVB-RCS like Network is presented. The envisaged Traffic Management schemes shall enable the SKN System to guarantee an adequate support of various Quality of Service (QoS) requirements and their application according to pre-defined Traffic Profiles established at connection set up phase with the support of physical medium access management functions. The functional architectures studied for the SKN Inter-Working Layer, from Internet protocols to SkyplexNet ones, and the SKN MAC layer have been also analysed on the interoperability level of these layers in order to deploy such functions as SKN connection mapping, packet scheduling and Bandwidth on Demand (BoD) policies. In this paper two different schemes of Traffic Management and MAC are presented reporting a detailed analysis of advantages and drawbacks of both approaches to be taken into account for future SkyplexNet system implementations.

Interactive IP-Network Via Satellite DVB-RCS

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.

Optimization of Satellite Access Lower Layers for the Transport of IP Datagrams

This paper presents a novel solution optimizing satellite access lower layers and system performances called variable size packets (VSPs) designed for the transport of Internet protocol (IP) datagrams or any packet type from the network layers characterized by a highly variable size. VSP objective is to maximize the efficiency of layers 1 and 2 through a joint optimization of access and transport mechanisms mainly for satellite systems addressing residential or corporate terminals market through a multiple-access scheme. It is particularly attractive for the return link of next-generation satellite systems to be IP-based, as a possible evolution of the digital video broadcast-return channel via satellite (DVB-RCS) standard. The VSP solution relies on the definition of multiple encapsulation sizes, and is associated to a waveform and an access adapted to variable size packets' transport. It uses the traffic's variable size nature to increase encapsulation efficiency, coding, and spectral efficiency performances, and system flexibility. It is well adapted to systems using an adaptive waveform leading to system capacity's increase and better performances. This paper describes the VSP principle, advantages and possible high-level system tradeoffs. It then focuses on one critical issue, the coding, and presents a suitable coding scheme's choice with regards to performances and implementation complexity.

A Real-Time Algorithm for Timeslot Assignment in Multirate Return Channels of Interactive Satellite Multimedia Networks

Since the digital video broadcast-return channel via satellite (DVB-RCS) standard was released in 2000, developing an interactive satellite multimedia (ISM) network has become a hot issue. In order to provide high-speed multimedia services using a DVB-RCS system, it is important to efficiently and dynamically assign the timeslots to a number of terminals according to their various demands. Also, it is imperative to improve the degradation of link quality due to rain-fade attenuation in Ka-band satellite communications. As a result, multirate superframe structures should be implemented for a relatively low data rate at the cost of stable connection to terminals in rain-fade regions and a relatively high data rate to terminals in clear-sky regions. Timeslot scheduling in this environment is studied in this paper. We mathematically formulate the timeslot assignment problem as a nonlinear integer programming problem and develop an efficient real-time solution algorithm. Extensive simulation results show that our algorithm successfully finds a feasible solution with optimality gap less than 0.05% within about 5 ms at Pentium III PC. We believe that our algorithm can be utilized as a guideline in developing real-time timeslot assignment algorithms for ISM networks.