ipv6 networks over dvb-rcs satellite systems

INTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS AND NETWORKINGInt. J. Satell. Commun. Network. 2008; 26:45–56Published online 18 October 2007 in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/sat.894

IPv6 networks over DVB-RCSsatellite systems

Ricardo Castellot Lou1,*,y, Antonio Javier Sanchez Esguevillas1, Borja de laCuesta Diego2, Belen Carro2, Linghang Fan3 and Zhili Sun3

1Telefonica I+D, Parque Technologico Walqa, Edif. 1, Ctra Zaragoza 330 km, 58 Huesca, 22199 Spain2University of Valladolid, Valladolid, Spain

3University of Surrey, Surrey, U.K.

SUMMARY

Satellite plays an important role in global information infrastructure (GII) and next generation networks(NGNs). Similarly, satellite communication systems have great advantages to support IPv6 (InternetProtocol 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 videobroadcast-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) forbroadband satellite systems and services using the technology presented above. This project is promotingthe 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 componentsdefined by the European DVB-S2 and DVB-RCS satellite broadband standards. Copyright # 2007 JohnWiley & Sons, Ltd.

Received 22 November 2006; Revised 13 August 2007; Accepted 21 August 2007

KEY WORDS: satellite; IPv6; DVB; SatSix; NGN; QoS; security; multicast

1. INTRODUCTION

Nowadays, high-speed access to the Internet is supported by cable or digital subscriber line(DSL) technologies as well as WiFi and WiMax. The cost of these technologies is significant andsuffers implementation issues, for example, limited geographic coverage. Owing to this reality,

*Correspondence to: Ricardo Castellot Lou, Telefonica I+D, Parque Technologico Walqa, Edif. 1, Ctra Zaragoza 330km, 58 Huesca, 22199 Spain.yE-mail: [email protected]

Copyright # 2007 John Wiley & Sons, Ltd.

ubiquitous broadband access (and with low cost) with global coverage is the objective of allInternet service providers (ISPs).

Broadband satellite access can be used to overcome the limitations, owing to its wide areacoverage and simple installation. The broadband satellite systems present advantages over otheraccess systems, such as high coverage, configuration flexibility, cost independence with distanceand reliability. However, the market availability of satellite access has been limited until now;mainly due to that no single interactive access protocol for satellites has been widely supported.As a consequence of this, proprietary solutions sustained only low-volume production ofequipment, without benefiting from the economies of scale of other access technologies (cable orDSL) and hence higher cost. Further information on this topic can be found in [1, 2].

A standard satellite access promotes higher volume production, leading to lower equipmentcost. This allows the same equipment to be exchanged among several satellite systems. It is alsodesirable for satellite communication service providers/operators as it protects their investmentthrough the availability of equipment from alternative suppliers.

Broadband satellite systems offer several solutions to the problems encountered by ISPs tooffer universal broadband services. The main problems are presented below:

* high cost of the last section of the access distribution network (last mile access); and* two-way interconnection of isolated terrestrial networks, low cost and high-availability

broadcast (or multicast) overlay for terrestrial networks.

Owing to these reasons, the digital video broadcast-return channel via satellite (DVB-RCS)standard is adopted as the baseline of the solution presented in this paper, as it becomes widelyemployed. Digital video broadcast-satellite (DVB-S) is designed primarily for broadcasting(rather than typical interactive IP applications as web browsing, e-mail, FTP, etc.), whereasDVB-RCS is designed to provide return link via satellite for interactive services.

IPv6 over DVB-RCS technology has been studied, analyzed and simulated in severalEuropean projects. Nowadays, 14 partners all around Europe including pioneer Telecomcompanies, such as Telefonica I+D, or universities, such as the University of Valladolid and theUniversity of Surrey, are working together in the SatSix project [3] in order to improve thesolutions and results given on the previous European projects as basis for further developments.Since SatSix is currently in its first stage, in this tutorial paper we will make a review of the keyissues in IPv6 satellite networks over DVB-RCS.

2. SATSIX PROJECT AND ITS OBJECTIVES

The SatSix project will implement innovative concepts and cost-effective solutions forbroadband satellite systems and services. A prime focus of this project is to introduce IPv6protocol into satellite-based communication systems. This project aims at developing a fulltechnical definition at system level and sub-systems level (from application layer to transportlayer). The SatSix system will be a service platform built upon the basis established by theEuropean DVB-RCS and DVB-S standards.

The main objectives of SatSix are to lower the cost of broadband satellite access through thedevelopment of new satellite access techniques and the integration of wireless local loops (WiFiand WiMax) and to develop recommendations, test beds, trial networks showing how satellite

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Copyright # 2007 John Wiley & Sons, Ltd. Int. J. Satell. Commun. Network. 2008; 26:45–56

DOI: 10.1002/sat

broadband access will integrate next generation networks (NGNs), based on IPv6, and supportnew multimedia applications. The technical objectives of the project are:

* to define how satellite networks should integrate NGNs and support new applications(including IPv6);

* to enhance the operators’ and industry’s position in satellite broadband multimediasystems by exploiting the common components defined by the European DVB-S2 andDVB-RCS satellite broadband standards; and

* to reduce the satellite access costs.

The SatSix project will thus focus on satellite systems that offer attractive solutions to theaccess segment of wider networks in several main scenarios that allow:

* for all types of users to access the Internet and other widely distributed networks (e.g. virtualprivate networks, VPNs) directly or via local networks (WiFi or WiMax, LAN, etc.) and

* for corporate and SME users to set up (virtual) private networks via a backbone includingsatellite systems inter-working with terrestrial networks where necessary.

SatSix will enable Internet access via satellite for end-users. The aim is to provide thecustomer with a wide choice of broadband services. Satellite networks based on the two-wayDVB-RCS standard have been introduced for duplex communications. The latest revision ofDVB-RCS standard now includes DVB-S2 on the forward link and the capability to supportdynamic rate adaptation and adaptive coding and modulation (ACM) both on the forward andthe return link. The expected results of the project are the following:

* impact of integration of IPv6 protocol into DVB-S2/DVB-RCS;* definition of inter-networking aspects [Sat + WiFi, Sat + WiMax, etc.];* definition of hybrid satellite systems [OBP + Transparent payload];* integration of innovative applications into satellite networks;* definition of quality of service (QoS) for the different scenarios; and* critical path validation through emulated and live test beds.

In terms of network scenarios, SatSix will look at the latest trends in networking: IP access fortriple play service to consumers and Ethernet/VLAN access for VPN. The SatSix analyses morecomplex and complete scenarios; these scenarios are: residential, corporate and collective access(satellite and wireless technologies). Corporate scenario, based on end-to-end VPN over satellite,will handle applications such as tele-learning, co-design or distributed remote help. Features suchas multicast support, end-to-end security, mobility or QoS guarantee will also be present. On theother hand, residential application will include digital and interactive TV, a general Internetaccess and telephony, providing users triple play services. Finally, collective access terminalscenario will use WiFi and WiMax access for users distribution behind satellite terminals.

For each of these scenarios, the requirements in terms of applications, QoS, security andmulticast have been analyzed in order to adapt different satellite access solutions to therequirements of each kind of user. Moreover, one of the aims of SatSix is to find a manner toprovide a global Internet access via satellite, of course, combining satellite with terrestrial

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technologies including LAN, WiFi or WiMax. A global view of the system is depicted inFigure 1.

One of the significant improvement techniques introduced with SatSix is in the manner usedto provide QoS, security, mobility, etc. (and the results obtained).

This paper is related to the definition of SatSix architecture and its subsystems (QoS,mobility, security, etc.). They will be the basis of development of commercial systems for futuresatellite/IPv6 networks.

3. DVB-RCS AND THE SUPPORT OF IP TRANSPORT

Satellite access networks for IP service provision based on DVB-RCS standards are currentlybeing extended around the world; there are still very few available terminals and systems on themarket. These systems employ mainly ‘transparent’ payloads on-board satellite and oftenprovide star connectivity to the core network through large hub stations.

The forward link is provided by DVB-S (or the DVB-S2, a further development of DVB-S)for broadcasting at first and a satellite return channel for duplex communications. Concerningthe forward link, the European Telecommunication Standards Institute (ETSI) standardspecifies the use of MPEG-2 (Moving Pictures Experts Group) for packetization, whilst thereturn link uses optional MPEG-2 or ATM (Asynchronous Transfer Mode) packetization, butneither of these links is very optimized for a variable packet length, bursty IP traffic.

The DVB-RCS interactive satellite access standard has been accepted by ETSI, but it does notspecify widely many aspects of the layer 2 Control and Management Planes, especially those

Figure 1. Global view of the SatSix system.

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concerned with QoS and resource control and management, and the performance of the IPtraffic over DVB-RCS depends widely on this.

The return link in DVB-RCS is based on a multiple-frequency time-division multiple-accessscheme, where the capacity is divided into slots within a time and frequency frame and allocatedto terminals. Different RCSTs (return channel satellite terminals) can simultaneously access thereturn channel capacity; hence, medium access control (MAC) is necessary. NCC (NetworkControl Center) is responsible for resource management. The performance of IP over DVB-S/RCS depends largely on the adopted MAC protocol. The MAC protocol determines theefficiency of uplink resource utilization based on unpredictable traffic profiles. Research into aDAMA (demand-assigned multiple access) protocol for this technology is one of the key factorsfor its future adoption as a fully symmetrical link supporting IP communications [4, 5].

Moreover, DVB-RCS is an ‘open’ standard designed to allow interoperability between differentimplementations of the DVB-RCS systems and to permit the adaptation to various higher layersvia the MPE (multi-protocol encapsulation) layer 2 protocol. These aspects are defined by theDVB-RCS standard, but other aspects such as the mapping of QoS classes and the allocation ofresources between an IP layer and DVB-RCS are left open to allow the system designer to choosethe option to compete with the best implementations. Therefore, additional functions at layer 2need to be specified to adapt IP services (e.g. DiffServ, IntServ, IP multicast) fully to DVB-RCS.

In terms of IP service handling, as we commented before, it is clear that the DVB standardsare neither optimal nor complete. To find a better encapsulation efficiency, the IETF (Internetengineering task force) works on ultra-lightweight encapsulation (mechanism for the transportof IPv6 datagrams over MPEG-2 Transport Streams) and the possibility offered by DVB-S2,due to which generic streams (instead of MPEG-2-based transport streams) have to be leveragedand their applicability to broadband satellite systems assessed (including OBP, on boardprocessing, systems).

DVB-RCS standards propose some guidelines for the definition of connection controlprotocol, which is crucial not only for mesh systems operation through OBP but also for addressresolution and QoS support in systems with star topology. The performance of IP over DVB-S/RCS and efficiency of resource utilization also largely depends on the MAC protocol adopted aswell as the unpredictable traffic profiles. The SatSix will carry out research into combined IP andMAC QoS functions for this technology as one of the key factors for its future adoption as afully symmetrical link supporting IP communications.

3.1. Migrating from IPv4 to IPv6

The introduction of IPv6 into the global information infrastructure (GII) and its migration fromIPv4 will be hugely beneficial for services, but it also has a complex technical problem. It is alsoclear that transition to ubiquitous IPv6 operation will take a long time and will be realized indifferent phases. This is not only due to the non-centralized ownership and management of theInternet but also due to the fact that Internet is made of a variety of technologies andsubnetworks. Hence IPv4 and IPv6 are going to coexist in Internet for a long time and strategiesfor transition from IPv4 to IPv6 form have been an important part of the IPv6 [6].

The major factor that will condition this transition will be the rapid growth of Internet users.The imperative need of embedded Internet devices jointly with the intention to provide an IPaddress for every 3G phone will demand the address space of IPv6. In Europe, where 2G cellularsystems have been such a market success and where most research has been carried out in 3G



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systems, the need for dedicated and statically allocated IP addresses for new IP mobility featureswill drive IPv6 adoption soon. Furthermore, the IPv6 enhancements for QoS management,mobility management and security will justify rapid transition [6].

As the transition from IPv4 to IPv6 will be a gradual process, satellites will play an importantrole in the IPv4 to IPv6 migration. This is so because the satellites allow easy interconnection ofmany IPv6 islands.

A future test satellite access network should therefore be designed to operate on the basis ofIPv6. It should also provide compatibility for end-to-end user applications with both IPv4 andIPv6 transport in the core network.

The bi-directionality issue and the link multicast issue are not IPv6-specific ones, but IPv6enhances the functionality of the IP layer by introducing IPv6 neighbour discovery and IPv6stateless address auto-configuration, and these functions require bi-directional links and linkmulticast between nodes attached to the satellite link. Deploying satellite networks withoutthese characteristics means removing the possibility of using mechanisms relying on them.

A general model for an IP-oriented satellite architecture was proposed in projects such asSATIP6 [7] or ICEBERGS [8]. This project is focused not only on IP/satellite transport issuesbut also on IP networking over generic links which are then applied to the satellite context.These issues comprise general inter-working aspects and resource management in the satellitesegment, IP QoS provision, IPv6 mobility support and multicast support, security [9].

3.2. DVB-RCS and the support of the Internet Protocol version 6 (IPv6)

On the basis of the SATIP6 works, the SatSix develops a test bed for trials with IPv6 stack beinginstalled in hosts with Linux and Windows XP operating systems. Once IPv6 stack is installed, itwill be possible to do a practical comparison among different videoconferencing clients thatsupport IPv6 to extract conclusions about parameters of QoS.

SATIP6 project performed pioneer research over IPv6 support on satellite network. It ismainly focused on IPv6 addressing and routing, usage of IPv6 stacks (Linux and XP), usage ofIPv6 applications (including the porting to IPv6 of GnomeMeeting), development of a novelmulticast IPSec scheme compatible with IPv6, mobile IPv6 development and demonstration,porting of transport PEPs (performance enhancing proxies) to IPv6, giving recommendationsfor transition mechanisms, study of the mapping of IPv6 neighbour discovery protocol onSatellite address resolution protocol and study of MLD (multicast listener discovery) multicastgroup management protocol.

The transition design efforts resulted in a basic transition mechanisms specification for IPv6hosts and routers that specifies the use of dual IP layer, providing complete support for bothIPv4 and IPv6 in hosts and routers, and IPv6-over-IPv4 tunnelling, encapsulating IPv6 packetswithin IPv4 headers to carry them over IPv4 routing infrastructures [9].

There are two alternative solutions to provide IPv6: the use of IPv6 tunnelling and theintegration of native IPv6. SatSix will focus on native IPv6 support.

4. SUBSYSTEMS

In terms of IP service handling, DVB standards are neither optimal nor complete. MPEG-2packetization is specified on the forward link while the return link uses optional MPEG-2 orATM packetization. The main problem is that neither of these links are optimized for

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variable packet length, bursty IP traffic. Moreover, DVB-RCS was conceived as a ‘minimum’standard designed to allow basic interoperability between DVB-RCS systems and adaptationto various higher layers via the MPE layer 2 protocol. Therefore additional functionsshould be specified in order to fully adapt IP services (e.g. QoS, security, multicast) toDVB-RCS.

4.1. Providing QoS in an IP-based satellite network

The satellite segment provides QoS in terms of packet loss, delay and jitter. The satellite segmentinterworks with Internet QoS DiffServ in order to provide end-to-end QoS at network level. Theterminal model performs this interworking in terms of signalling and QoS parameters mapping.

The SatSix system is mainly composed of the following entities:

* the NMS (network management system), helping the NCC to build all the required DVB-S, DVB-RCS and MPEG2 tables;

* the NCC, serving satellite access requests from the many RCSTs;* the RSGWs (regenerative satellite GateWays), providing interfaces with terrestrial

networks such as PSTN or Internet;* the RCSTs, providing the user with access to services delivered by the service provider; and* terminals;* ISP.

The functional QoS architecture in SatSix is based on ETSI BSM approach [10]. Its relevantissues are the separation between services and transport, the addition of QoS to IP-basedtransport and the capability for innovative service provision. The different functions related toQoS are divided into two distinct planes: one for all transport functions and the other for allservice management functions.

* Application plane provides the service to users. Service is requested by user/call signallingprotocols.

* Transport plane provides a packet-oriented service and the desired network QoS.

DiffServ [11] is the architecture proposed in order to achieve QoS, and it offers advantageswith regard to scalability and implementation simplicity. It is based on traffic management ondifferent behaviour aggregates. This layer 3 QoS mechanism is integrated with the QoScapabilities offered by DVB-RCS in order to provide end-to-end QoS.

The IP QoS relies on the notion of classful queuing discipling. The traffic needs to be classifiedinto classes to determine where different filters are used. Figure 2 illustrates a basic traffic classhierarchy, defining a first level (EF, AF and BE) and a second one with IP QoS traffic classes(EF, AF1 and AF2, BE). The last level is dedicated to traffic marking (or re-marking), allowingto set the DSCP field.

Figure 3 shows the end-to-end QoS architecture that is being used in the SatSix project toprovide QoS in the proposed scenarios.

4.2. Security

End-to-end security, which can be provided at any level of the protocol stack, such asapplication, transport or network layers, is a very important objective for SatSix project. In



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Figure 2. Basic traffic class hierarchy.

Figure 3. SatSix end-to-end QoS architecture.

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general, and for a security of this kind, it is needed to establish a relationship between users ofthe end-to-end security system through a security management system. Security at theapplication layer is also being investigated in relation to the innovative applications used inSatSix project. The following techniques are going to be evaluated: XML encryption and digitalsignatures, secure Web services and digital rights management (DRM) systems.

This evaluation will include the design and development of the previously presented techniquesfor SatSix applications. SatSix will focus on networking issues with regard to securing end-to-endservices and DRM and roles that network entities will be in DRM and secure end-to-end services.In addition, interworking with network and link layers security will be performed. Finally,tackling the security problems at various layers of the protocol stack (application, network andlink layer) will insure achieving a robust and new concept in securing SatSix network andapplications. Therefore across-layer security optimization is a major objective in SatSix work.

4.3. Multicast

The following issues are being addressed in a SatSix project in relation with multicast support(SatSix looks for a reliable multicast over satellites). SatSix will make an analysis andadaptation of MLDv2 (multicast listener discovery protocol version 2) for a satelliteenvironment. Moreover, partners of SatSix will work on multicast routing source-specificmulticast, inter-domain routing and architecture issues) and dynamic address resolution andIPv6 multicast translator gateway design.

4.4. Mobility

The work on mobility in SatSix is focused on making a performance analysis andimplementation of MIPv6 (mobile IPv6) mobility, where an MIPv6 separate platform wasdeveloped. This platform includes mostly all functionality as specified in MIPv6 draft 24. MIPv6has been standardized and, due to it, further development of mobility in SatSix will be based onavailable platforms. The MIPv6 software will be firmly integrated with the SatSix software inorder to obtain seamless QoS support with mobility. Moreover, SatSix is also focusing on theextension of MIPv6 by defining a mobility architecture that allows regional registration asdefined in hierarchical mobile IPv6 (HMIPv6) to handle local mobility management in thesatellite terminal network (connected locally to the satellite terminal). Mobility enhancement,efficiency performance analysis and implementation by searching for available patches extendMIPv6 to include HMIPv6.

4.5. Transport protocols and PEP

Multimedia, until now, has mainly used UDP as a transport protocol. However, the lack ofcongestion control (CC) is a serious difficulty that poses a growing threat of network congestion.In the future, this could lead to a collapse of the Internet and hence lead to the IETFdevelopment of a new transport protocol: datagram congestion control protocol (DCCP). Thisprotocol is designed as a replacement for UDP for most multimedia applications, and interfacesare being defined for multimedia codecs. A key feature of this solution is support for a range ofTCP-like CC functions. Furthermore, although it is known that there are potential advantagesin using DCCP compared with TCP over wireless/satellite links, the implications on theprotocol (efficiency, performance) and the requirements placed on such networks have not been



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studied fully. SatSix project provides an opportunity to evaluate the actual performance ofDCCP within the project test bed.

TCP is designed for different conditions than usually can be found in a satellite link such aslow-network latency, maximize bandwidth utilization, error detection and correction andcongestion avoidance and recovery via flow control mechanism. With the intention of improvingthe throughput, PEPs [12] is used to split the TCP connections into satellite and non-satellitesegments and run a modified TCP or even another protocol between the PEPs (over thesatellite). This is useful for filling up the satellite link pipe that has a high-bandwidth-delayproduct. PEP is not yet an official standard but is used to describe the set of proprietarymechanisms satellite vendors and systems integrators created to spoof TCP over a satelliteconnection. Solutions based on on-board satellite ‘split TCP’ have also been proposed as analternative to the more conventional gateway-based split TCP solutions.

Formerly, the PEP protocol developed at first for IPv4 was ported to IPv6. In SatSix the main focuson TCP and PEP will be the improvement of the interaction between the bandwidth-on-demand/DAMA algorithms and the PEPs. This work includes simulations and emulations for different trafficprofiles. Moreover, other aims of SatSix are the optimization of the PEP transport protocol solution.One candidate to investigate further would be the explicit rate control protocol solution [9].

5. CONCLUSIONS

SatSix benefits from the extensive experience gained from partners in other related projects(such as SATIP6 and Satlife) carried out in the recent years. Using the results of these projects, itwill be possible to implement a satellite-based communications system within IPv6 network.This system is based on the integration of IPv6 protocol (encapsulation, etc.) into DVB-S2/DVB-RCS with the following features supported: multicast, security (satIPSec), mobility, QoSand other relevant features.

Moreover, inter-networking aspects will be defined in order to use the technologies betweenSatellite and WiFi as well as between Satellite and WiMax jointly. Hence, SatSix is looking foruniversal Internet access (isolated areas, mountains, etc.).

Telefonica I+D will cover the technology gap required to diminish the costs and technicallimitations, thanks to advanced satellite and terrestrial integrated platforms and providing long-term expertise on networks and service aspects for IP broadband systems and NGNs.

As a result, the SatSix project will define and validate the key novel techniques both atsystem level and at sub-systems level. These will form the basis for the development of commercialsystems in future satellite/IPv6 networks. On the other hand, the development of IPv6 networks oversatellite system will help IPv6 to be introduced into other terrestrial networks. Thanks to thissolution (IPv6 networks over DVB-RCS satellite Systems) SatSix is making it possible for twocomplementary technologies, as DVB-RCS and IPv6, to work jointly with the consequentimprovements.

ACKNOWLEDGEMENTS

This paper is based on work undertaken in the SatSix (satellite-based communications systems within IPv6networks) project, whose consortium the authors want to acknowledge. This Integrated Project waslaunched under the fourth call of the 6th European Framework Programme.

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REFERENCES

1. Breynaert D, Newtec CEO. Perspectives for low cost satellite communications.World Conference on Information andCommunication Technologies for Capacity Building: Critical Success Factors, Paris, France, 2005.

2. Tardy I, Braten LE, Bichot G, Settembre M, Sesena J. Hybrid architecture to achieve true broadband access in ruralareas. Broadband Europe, Brugges, Belgium, 2004.

3. Satsix Partners. Satellite based Communication Systems within IPv6 Networks (SatSix), Full Proposal. SatSix’Partners, March 2005.

4. Le-Ngoc T, Jahangir IM. Performance analysis of CFDAMA-PB protocol for packet satellite communications.IEEE Transactions on Communications 1998; 46(9):1206–1214.

5. Khan MK, Peyravi H. Delay and jitter analysis of generalized demand-assignment multiple access (DAMA)protocols with general traffic. Proceedings of the 38th Hawaii International Conference on Systems Sciences,Washington, DC, U.S.A., 2005.

6. Sun Z. Satellite Networking}Principles and Protocols. Wiley: New York, 2005.7. SATIP6: satellite testbed for next generation protocols. Second International Working Conference on Performance

Modelling and Evaluation of Heterogeneous Networks (HET-NETs’04), Ilkley (GB), Alphand O, Berthou P, GayraudT, Josset S, Fromentin E (eds). 26–28 July 2004.

8. Aguiar JM, Carro B, Sanchez A, Cruickshank H, Liang L. QoS of multiparty videoconference over geostationarysatellites. Telecommunications Quality of Services: The Business of Success, QoS 2004. IEE: London, 2–3 March 2004.

9. Falk A, Pryadkin Y, Katabi D. Specification for the Explicit Control Protocol (XCP). Network Working Group(draft-falk-xcp-spec-01.txt) November 2006.

10. ETSI TS 102 462. Satellite Earth Stations and Systems (SES); Broadband Satellite Multimedia (BSM) Services andArchitectures: QoS Functional Architecture.

11. Blake S, Blake D, Carlson M, Davies E, Wang Z, Weiss W. An architecture for Differentiated Services. Internet RFC2475, December 1998.

12. Astuti D. TCP and Link Layer Enhancements in DVB-S/DVB-RCS. University of Helsinki, May 2004.

AUTHORS’ BIOGRAPHIES

Ricardo Castellot Lou holds a degree in Computer Science Engineering from theUniversidad de Zaragoza. He joined Telefonica IþD in 2003 as a scholarship holder inthe ‘Real Time Communications’ division, where he participated in the design anddevelopment of a project related to Voice over IP applications and platforms. From 2001to 2002, he worked as a scholarship holder in the banco zaragozano computer centre inthe systems analysis area based on UNIX platforms, where he acquired knowledge onthese platforms and databases. He is currently working for Telefonica I+D on severalEuropean projects concerning VoIP and multiconference services. Actually he wasinvolved in MUSE and PLANETS projects for universal broadband access and iscurrently in SATSIX. He is also coordinating the COGKNOW project, an IST-FP6eInclusion project, and the collaborates with other eInclusion projects (eABILITIES).

Dr Antonio Sanchez holds a Telecommunications Engineer and PhD degrees fromUniversity of Valladolid. He collaborated on research projects of the University withinternships from the University and the Ministry of Education. Subsequently heworked for Acotec, Cedetel and Euroconsulting Informatico where he participated inseveral development and network engineering projects, the last one involved with theSpanish Army and NATO. He joined Telefonica R&D as a Network Engineer wherehe was involved in several projects related to the IP-Network/Infovıa Plus, deployed inSpain and other countries of South America: international IP backbone, BGP4, QoS,MPLS, ADSL, cable, Voice over IP integration. Later he joined the VoIP divisionwhere he has led several international Telefonica projects (Spain, Europe and SouthAmerica) related to IP services. He has a sound knowledge of Real-TimeCommunications technology and has been consultant for the deployment and SWdevelopment of multimedia IP services for Telefonica Corporation (Telefonica ofSpain, Telesp, Telefonica Deutschland, Telefonica Moviles, Telefonica Data,TerraLycos, etc.). He currently coordinates R&D activities of the Telephone Services



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area. He has broad experience in European projects, both IST (FP5 ICEBERGS as coordinator, FP6MUSE,MEDIANET, SATLIFE, DAIDALOS) and TEN-TELECOM (VIP-TEN). He has also been proposed asevaluator for eTen and IST FP6. He is author of more than 20 international publications. Currently, he isalso an Associate Professor in the University of Valladolid.

Borja de la Cuesta is with Communication & Information Technologies researchgroup at the University of Valladolid, Spain, where he is researcher, and his researchis focused on Quality of Service in real-time services over Next Generation Networkand QoS architecture in Satellite systems. He worked in several European projects(IST FP6 MEDIANET and EUREKA CELTIC Initiative projects as MaCs andIMAGES). Currently he is working in the European IST project SATSIX and ESAproject Application layer QoS in DVB-RCS systems.

Dr Belen Carro is a PhD in Telecommunications and a TelecommunicationsEngineer. She is professor of the Telecommunications School at the University ofValladolid. Her research is focused on broadband access networks and advancedtopics on quality of service in multimedia systems. She is the principal investigator ofthe University of Valladolid in several IST Framework Program European researchprojects, such as ICEBERGS (FP5) and MEDIANET, Satsix and Opuce (FP6), alsoin CELTIC initiative projects (IMAGES, QUAR2, MaCS, PABIOS) and incollaborations with ESA and ETSI. She is also coordinating other national andregional projects related to the introduction of quality of service in broadbandsystems, as well as collaborations with key companies in the telecommunicationssector. Within these projects she is currently managing 10 doctoral theses. She haspresented many papers in national and international conferences and written articles

in important publications in the sector. Also, she has been reviewer of papers for several IEEE publicationsand conferences.

Dr Linghang Fan is a research fellow of Mobile Communications Research Group inthe University of Surrey, U.K. He received his BE in Automatic Control fromSoutheast University, China, and his MSc and PhD in Telecommunications fromUniversity of Bradford, U.K.From 1998 to 2000, he was a researcher in the University of Bradford and worked

on the EU projects SINUS and SUMO. In 2003, he joined the University of Surreyand worked on the EU projects STRIKE, Ambient Networks, MAESTRO andSATNEX. Currently, he is working on the EU project SATSIX. He has publishedmore than 20 papers in international journals and conferences.His research interests include mobile communications, mobile Internet and

satellite communications.

Dr Zhili Sun was a Senior Research Fellow from 1995 to 1997 and a Research Fellowfrom 1993 to 1995. From 1989 to 1993 he was a Postdoctoral Researcher in theTelecommunications Research Group at Queen Mary College, University ofLondon. In 1993, he joined the Networks Research Group. He has been the co-ordinator of the several EU ACTS IST, ESPRIT, TEN-Telecom and FP6 projects.As course leader, he lectures on Satellite Communications and networks and IPNetworking, LANs, Broadband Network Design, as part of the MSc course andindustrial short courses, and computer and data networks U/G course.

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ipv6 networks over dvb-rcs satellite systems

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