deliverable d8.3: vivaldi workshop - aristotle university of...

VIVALDI PROJECT

Deliverable D8.3: VIVALDI Workshop

24.12.2007

Project full title:

Advancing interactive Broadband satellite access by optimal convergence of session based services over DVB-RCS

Proposal/Contract no.: FP6-2004-IST-4 027762

SIXTH FRAMEWORK PROGRAMME PRIORITY 2

IST-Information Society Technologies

1. General Description

VIVALDI 30-Jan-08 /34

D 8.3: “VIVALDI Workshop”

Table of Contents 1. General Description......................................................................................................................3 2. Objectives and Structure of INNSS’07 .........................................................................................4

2.1 Objectives of INNSS’07..........................................................................................................4 2.2 Structure of INNSS’07............................................................................................................4

3. Program and Presented Papers ...................................................................................................7 4. Summary ......................................................................................................................................9 5. Annex......................................................................................................................................... 10

2.1 TKK Presentation ................................................................................................................ 10 2.2 Gilat Presentation................................................................................................................ 16 2.3 AUTh Presentation.............................................................................................................. 28

1. General Description



1. GENERAL DESCRIPTION The present deliverable presents the activity developed in the framework of VIVALDI, regarding the dissemination of VIVALDI’s output through the organization/participation in a workshop of relevant interest. Specifically, during July 2007, VIVALDI organised jointly with other projects and participated in the “International Workshop on IP Networking over Next-generation Satellite Systems” (INNSS’07), that was held in Budapest following the annual IST Mobile and Wireless Communication Summit. The main objective of the VIVALDI’ participation in a workshop is twofold and involves the bidirectional exchange of data between the VIVALDI and the rest of the scientific/commercial community and the public in general. In particular, workshops provide VIVALDI with the opportunity to accomplish: i) the dissemination of the project’s goals and achievements to the public; and ii) deeper acquaintance with stimulating knowledge originating from other Satellite and/or VoIP involved institutions. In the following chapters, the structure, objectives, participants and the context of the INNSS’07 in general is presented.

2. Objectives and Structure of INNSS’07



2. OBJECTIVES AND STRUCTURE OF INNSS’07 2.1 Objectives of INNSS’07 As it becomes apparent from its title, INNSS’07 aims at summarizing as well as promoting the research performed on the issue of optimizing IP communication over the current and oncoming satellite systems. In detail, with the boom of Internet, IP-based applications, such as WWW and multimedia, have been an essential part of our life, and there is an ever-increasing demand for accessing high-speed Internet services anywhere and anytime. This trend unavoidably has huge impacts on the design of the next-generation satellite systems. On the other hand, with its broadcasting nature and unique coverage, satellite systems also can play an important role in the next-generation Internet. For example, satellite systems can be a good driver for the deployment of IPv6 in the Internet, and can provide a fast way to reach end-users because they do not rely on construction of a high-speed terrestrial networks.

2.2 Structure of INNSS’07 In essence, the INNSS’07 has been formatted as a common workshop of five IST projects sharing similar or neighbouring fields of interest under the umbrella of IP communication over satellite infrastructure. Thus, as it becomes obvious, the participation of VIVALDI in such a workshop has risen as a unique opportunity for exchange of ideas on such a rapidly evolving topic. The workshop was organised by the following EC funded projects. VIVALDI has contributed to the organisation of the workshop by participating in the Technical and Steering committee’s: i. SATSIX

Title: Satellite-based communications systems within IPv6 networks Website: http://www.ist-satsix.org

ii. SATNEX

Title: Satellite communications network of excellence Website: http://www.satnex.org

iii. IMOSAN

Title: Integrated Multi-layer Optimization in broadband DVB-S.2 Satellite Networks

Website: www.ist-imosan.gr

iv. VIVALDI Title: Advancing interactive Broadband satellite access by optimal

convergence of session based services over DVB-RCS Website: http://newton.ee.auth.gr/vivaldi




v. SATLIFE

Title: Satellite Access Technologies - Leading Improvements For Europe Website: http://www.satlife.org

Furthermore, the committees of the Workshop consisted of exceptional members of the scientific comunity. Specifically: i. Organizing Committee

General Co-Chairs: Linghang Fan (University of Surrey, United Kingdom) Haitham Cruickshank (University of Surrey, United Kingdom)

ii. Steering Committee

Michel Mazzella (Alcatel Alenia Space, France) Anton Donner (DLR, Germany) Avi Gal (Gilat, Israel) Catherine Morlet (ESA) Istvan Frigyes (Budapest University of Technology and Economics, Hungary) Isabelle Buret (Alcatel Alenia Space, France) Barry Evans (University of Surrey, United Kingdom) Erich Lutz (DLR, Germany) Zhili Sun (University of Surrey, United Kingdom) Carlo Caini (University of Bologna, Italy)

iii. Technical Program Committee

José Antonio Guerra Expósito (Hispasat SA, Spain) Cedric Baudoin (Alcatel Alenia Space, France) Pascal Berthou (CNRS/LAAS, France) Hermann Bischl (DLR, Germany) Ricardo Castellot (Telefonica I+D, Spain) Bernhard Collini-Nocker (University of Salzburg, Austria) Tomaso de Cola (CNIT, Italy) Borja de la Cuesta (University of Valladolid, Spain) Gorry Fairhurst (University of Aberdeen, United Kingdom) Thierry Gayraud (CNRS/LAAS, France) Giovanni Giambene (University of Siena, Italy) Sunil Iyengar (University of Surrey, United Kingdom) Lei Liang (University of Surrey, United Kingdom) Mario Marchese (University of Genoa, Italy) Inge Melhus (SINTEF, Norway) Robert Mort (Systek, United Kingdom) Niovi Pavlidou (Aristotle University, Greece) Antonio Pietrabissa (University of Rome, Italy) Filippo Rodriguez (Telespazio, Italy) Robert Rumeau (CNES, France)




Arjuna Sathiaseelan (University of Aberdeen, United Kingdom) Sandro Scalise (DLR, Germany) Alessandro Vanelli-Coralli (University of Bologna, Italy) Andreas Voigt (Fokus Fraunhofer, Germany) Lloyd Wood (Cisco) Ana Yun (Alcatel Alenia Space, Spain)

3. Program and Presented Papers



3. PROGRAM AND PRESENTED PAPERS

Time Program

8:50 – 9:00 Welcome and reception

9:00 – 9:20

New Architecture for Next Generation Broadband Satellite Systems -- the Satsix Approach Cedric Baudoin Thales Alenia Space

9:20 – 9:40

SATLIFE: A big step into the enhancement of the regenerative satellite generation Miriam Catalán Hispasat

9:40 – 10:00 SATSIX Satellite System and Network Elisa Callejo Thales Alenia Space España

10:00 – 10:20

Fast IP Handover Between Satellite Network and Wireless LAN Network for high-speed trains Myung Hee Han Korea Aerospace University

10:20 – 10:40 SATSIX Mobility Architecture and its performance evaluation Inge Melhus SINTEF

10:40 – 11:00 Coffee Break

11:00 – 11:20

Cross-layer anticipation of resource allocation for multimedia applications over DVB-RCS based on SIP signalling Frédéric Nivor LAAS-CNRS

11:20 – 11:40 Radio Resource Management for next generation DVB-RCS systems Antonio Pietrabissa Univerity of Rome “La Sapienza”

12:00 – 12:40 Interworking Strategy between DVB-RCS and WiMAX Filippo Rodriguez Telespazio S.p.A.

12:40 – 13:00

The use of novel satellite broadcast technologies for the provision of integrated services Evangelos Pallis NCSR 'Demokritos'

13:00 – 14:00 Lunch Break

14:00 – 14:20 Service Integration in Satlife Regenerative Network Isaac Moreno Thales Alenia Space España

14:20 – 14:40 Satsix QoS Architecture Borja de la Cuesta University of Valladolid

3. Program and Presented Papers



14:40 – 15:00

SatSix and Recent Standardisation Results in ETSI Broadband Satellite Multimedia (BSM) networks Rob Mort Systek

15:00 – 15:20 IPv6 Networking Over Satellite For Mobile User Groups Axel Jahn Triagnosys

15:20 – 15:40 Multicast architecture for IPv6 over DVB-RCS Satellite Networks Ana Yun Thales Alenia Space España

15:40 – 16:00

PLATINE: DVB-S2/RCS enhanced Testbed for Next Generation Satellite Networks Cedric Baudoin Thales Alenia Space

16:00 – 16:20 Tea break

16:20 – 16:40 Overview of the SATSIX trials Aurora Ramos Telefonica I+D

16:40 – 17:00 ULE Link Layer Security for DVB Networks Sunil Iyengar University of Surrey

17:20 – 17:40 Comparison of Header Compression Schemes over Satellite Links Gerasimos Dimitriadis Aristotle University of Thessaloniki - AUTh

17:40 – 18:00

Implementing VoIP support in VSAT networks based on SoftSwitch integration Yosy Hecht Gilat Satellite Networks Ltd.

18:00 – 18:20

VIVALDI Meta-Architecture: Flexible QoS Provisioning over DVB-RCS Satellite Networks Teemu Kärkkäinen Helsinki University of Technology TKK

18:20 – 18:40 Secure Multicast in the Broadband Satellite Multimedia Networks Haitham Cruickshank University of Surrey

18:40 Close the Workshop It needs to be mentioned the fact that the proceedings of the INNSS’07 shall be soon published in a book. Moreover, the presentations of VIVALDI partners (TKK, Gilat and AUTh) are available in the Annex section.

4. Summary



4. SUMMARY Through the process of INNSS’07, VIVALDI partners had an excellent opportunity to present their work to other researchers with common fields of interest as well as acquiring a very thorough and representative view of all the current trends regarding IP communication over satellite channels. In particular, on behalf of VIVALDI three different working fields have been presented: i. “Comparison of Header Compression Schemes over Satellite Links”, prepared by

Gerasimos Dimitriadis, Aristotle University of Thessaloniki – AUTh ii. “Implementing VoIP support in VSAT networks based on SoftSwitch integration”,

prepared by Yosy Hecht, Gilat Satellite Networks Ltd. And iii. “VIVALDI Meta-Architecture: Flexible QoS Provisioning over DVB-RCS Satellite

Networks”, prepared Teemu Kärkkäinen, Helsinki University of Technology TKK In this framework, INNSS’07 served in the most efficient way its purpose for dissemination of knowledge among adjoining European projects and of course towards any interested attendee.

5. Annex



5. ANNEX 2.1 TKK Presentation

VIVALDI Meta-ArchitectureFlexible QoS Provisioning for SIP over

DVB-RCS Satellite

HELSINKI UNIVERSITY OF TECHNOLOGYNETWORKING LABORATORY

Teemu Kärkkäinen, [email protected]

Agenda

• The problem: Real-time media over DVB-RCS• Different solution approaches• VIVALDI Meta-Architecture• Implementations

5. Annex





The Practical ProblemSat. Service Customer

Sat. Service Provider

Internet

Hub Terminal

InternetUser



The Conceptual Problem

Link Layer (DVB-RCS)

Network Layer (IP)

Application Layer (SIP)

QoS

Requirem

ents

Mechanisms that determine QoS

Requirements for QoS

DiffServ

5. Annex





The Functional Problem

• Detection of real-time traffic• Designation of traffic flows into QoS classes• Call admission control• Busy condition handling



Approach 1: Centralized ControlSat. Service Customer


Internet

Hub Terminal

VoIP Server (SIP Proxy)

5. Annex





Approach 2: Transparent OperationSat. Service Customer


Internet

Hub Terminal

VoIP Server (SIP Proxy)

3rd PartyVoIP Provider

Data Center



Meta-Architecture

Data Path

SignalingSignaling Server

PushbackSignaling Admission Control Unit

Module ControllerConfig.Source

FlowM

odule

FlowM

odule

FlowM

odule

FlowM

odule

Flow information

Decision / Instruction

5. Annex





Implementation 1: Centralized

Data Path

SignalingSignaling Server

Admission Control Unit

Module ControllerFlow

Module

Flow information




Implementation 2: Fully Transparent

Data Path


Module ControllerConfig.Source

Header

Module

RTP

Module

Flow information


5. Annex





Implementation 3: SIP “SoftSwitch”

Data Path


Module ControllerSIP

SoftSwitch

Flow information


Thank You!Teemu Kärkkäinen

[email protected]

5. Annex



2.2 Gilat Presentation

VoIP for SkyEdge

Satellite communications based on Geo-synchronous satellites are characterized by the following:

High delay caused by the propagation path of the information from earth to the satellite and back (about 250[ms] and 500[ms] round trip).

High cost of BW.Often, the inbound path is a FTDMA channel with

bursts.

Transporting VoIP over a satellite medium is a demanding and challenging task: QoS must be carefully supplied so as to support the requirements of minimal delay and jitter while consuming minimal bandwidth.

VoIP for SkyEdge

This task may be divided according to the following:Identify a call. This functionality must be achieved

relatively fast so as to provide resources for the call beforethe actual flow of media commences.

Identify the type of the call: Be it star, mesh or local. Each such type requires a different allocation pattern: A star call requires timeslot allocation and some resources at the hub to deal with the media, a mesh call would need special dedicated mesh resources on both participating VSATs, a double-hop mesh call would require timeslots to both participating VSATs, a local call requires no resources and the media must not travel over the satellite medium.

Identify the resources required for the call (e.g. codec BW).Reject a call for which there are insufficient resources.Identify the media flow itself, once it commences.Compress the media and send it over the proper satellite

resource.

5. Annex



VoIP for SkyEdge

System characteristicsEnd-to-End VoIP system.SIP and H.323 support concurrently.Virtual circuit approach for QoS guarantee.Graceful termination with proper cause if there are no

resources to make a call.RTP manipulation for BW efficiency.CODEC filtering mechanism to assure optimal working

point (parametric).Frame packing performed by VSAT/VPP regardless of

CPE configuration. Both jitter reduction and configuration robustness achieved.

Mesh support.

VoIP for SkyEdge

System characteristics (continued)Fax T.38(UDP) support.No specific CPE imposed on customer.Interface with external networks supported.Central management includes CDR for billing.Coexists with data applications as native voice does with

all of the QoS benefit implications.Runs on both SkyEdge Pro, Gateway and SkyEdge IP

VSATs.MVoIP and native voice can run on the same network-

even the same VSAT concurrently.Requires: DCAS, VPP, SoftSwitch.

5. Annex



VoIP for SkyEdge

So how do we do it in the SkyEdge system?We require all CPEs to register with the SoftSwitch.We require all call signalling to be directed to the

softSwitch (H.323 routed mode, SIP stateful proxy).The softSwitch has an interface with DCAS. Each time a

call is made, the SoftSwitch tells DCAS all of the information required for the DCAS to:

Reject the call if no resources are availableAllocate resources for the callAllocate only the exact resources required, and not

exceed them.DCAS allocates resources: VPP ports, CSRM VDA, VSATVSAT(VRPP) receives the assign message and starts

listening on the LAN port for traffic that is sent to the other side of the call.

VoIP for SkyEdge

VSAT then strips RTP/UDP/IP headers, formats the G.723/G.729/… frames into an internal format message which is sent to the VPP.

The number of frames in the message is according to the network setting, not what the CPE sends. User is relieved of this configuration detail.

VPP receives the internal format packet and builds an RTP packet which is sent towards the Hub-side CPE engaged in the call.

The reversed side is similar in nature.

5. Annex



Architecture “End-to-end VoIP”

NMS

DCAS

RF

Two WayVSAT

VPP

Gateway

Internet

LANResidential

Gateway

Phone

User PC

LANVideo conferencing equipment

Fax

LAN

NMS

DCAS

RF

ResidentialGateway

Phone

User PC

Two WayVSAT

LAN

SoftSwitch

Gateway

VoIPNetwork

Video conferencing equipment

ProprietaryProtocol:A,B, RTP ports, codec, bandwidthRequest-Ack/denial

VPP

RAS/H323

AssignAssign

Setup Req

Setup Ack

Internet

5. Annex



NMS

DCAS

RF

ResidentialGateway

Phone

User PC

Two WayVSAT

LAN

SoftSwitch

Gateway

VoIPNetwork


ProprietaryProtocol:A,B, RTP ports, codec, bandwidthRequest-Ack/denial

VPP

RAS/H323

Internet

AssignAssign

Setup Req

Setup Ack

NMS

DCAS

RF

ResidentialGateway

Phone

User PC

Two WayVSAT

LAN

SoftSwitch

Gateway

VoIPNetwork


RTP stack

VPP

RTP stack

RTP

Gilat VoiceRTP

Analog

Internet

Analog

5. Annex



NMS

DCAS

RF

ResidentialGateway

Phone

User PC

Two WayVSAT

LAN

SoftSwitch

Gateway

VoIPNetwork


RTP stack

VPP

RTP stack

Gilat Voice

RTPAnalog

Internet

Analog

HTTP

To DPS?

To VPP?RTP

NMS

DCAS

RF

ResidentialGateway

Phone

User PC

Two WayVSAT

LAN

SoftSwitch

Gateway

VoIPNetwork


VPP

Internet

Data path: VoIP signalling

DPS

5. Annex



NMS

DCAS

RF

ResidentialGateway

Phone

User PC

Two WayVSAT

LAN

SoftSwitch

Gateway

VoIPNetwork


VPP

Internet

Data path: Voice

DPS

NMS

DCAS

RF

ResidentialGateway

Phone

User PC

Two WayVSAT

LAN

SoftSwitch

Gateway

VoIPNetwork


VPP

Internet

Data path: RTCP

DPS

5. Annex



VoIP for SkyEdge

Solution ProsEnables total QoS. The voice and data paths are

completely separated from each other and there can be no interference caused by data traffic such as FTP upload and the voice traffic.

There is no interference between different voice calls, each call has its satellite resources reserved for the entire duration of the session.

The access provides a jitter-less medium for the voice data, which results in a superior voice quality.

It is possible to reject a call if there are no resources available, and provide a proper cause.

The bandwidth requirement is known from the signalling session, there is no need to assume bandwidth requirement a-priori, or to spend time in estimating the actual bandwidth.

Decisions regarding satellite resources are taken where the VoIP decisions are taken: At the softswitch.

VoIP for SkyEdge

Solution Pros (continued)No need to implement complex logics at the VSAT.The VSAT implementation is protocol agnostic – it is only

aware of RTP.The DCAS is protocol agnostic, and only aware of the

protocol between itself and the softSwitch.Using a softswitch from an external vendor brings the

benefits of exploiting the know how of expert – the softSwitch vendor, and concentrate on the satellite-unique issues. It also enables the system to benefit from the VoIP market trends and developments; (to expand in the directions the market is growing in terms of new protocols, new protocol version, redundancy, cost reduction etc).

Enables potential support for lawful interception, also in mesh modes.

May enable support for encrypted signalling (because the encrypted tunnel must be between the CPE and the softswitch) - something that "Transparent" systems can't achieve.

5. Annex



VoIP for SkyEdge

Solution ConsNot "transparent". If a carrier wants to use its

existing softSwitch, it can't do so. Although softSwitch to softswitch communications enables such a topology, usually the carrier will not want some of the subscribers to be managed in one softswitch and others on another.

Forces the service provider to be a telephony service provider, even if it is not its intention – the service provider must manage the subscribers, provide class 5 services and comply with regulations that otherwise it was exempt of such as lawful interception, emergency calls.

VoIP for SkyEdge

Solution ConsDoes not provide support for protocols such as

Skype – that are either proprietary and wouldn't be recognized by the softSwitch, or their topology is not centric, or do not use RTP.

In case of a VSAT where there are many calls, it cannot benefit from statistical multiplexing based on silence suppression.

Has problems with VLAN support.Forces the network to work in a working point

where a certain codec is most efficient. If other codecs are used, efficiency may deteriorate. Other applications may also perform less well.

5. Annex



VoIP for SkyEdge

Adaptation to DVB-RCS environmentDVB-RCS access scheme poses a few challenges

to the above described concept No special satellite resource type.No proprietary headers in the return channel.Strict resolution (ATM cells/MPEG frames).A limited number of channel IDs

It can be shown that with some adaptations, the concept is still valid even in the DVB-RCS environment, providing basically the same advantages and possibly more.

VoIP for SkyEdge

The method to be used to request DVB-RCS resources would be CRA

NCC analyzes the call needs and allocates the required resources to the RCST

A minor adaptation of the standard is required to allow dynamic allocation and de-allocation of CRA resources to an RCST on a per-call basis,

Providing better efficiency may also be achieved through the a-priori knowledge of the media stream end-to-end characteristics such as UDP ports. This enables header compression to be applied on each media stream, removing even the IP headers, and reconstructing them on the other side.

5. Annex



VoIP for SkyEdge

When performing IP header compression, some deviation from the DVB-RCS standard is required due to the fact that the packets are no longer IP – proper modification of the standard in the context of session management should enable this support.

header compression may require additional information transfer between the two ends of the satellite link –information not currently available within the DVB-RCS specs. C2P, a new protocol currently under development, may be applied to provide such information transfer.

It must be considered how to provide virtual circuit implementation in the DVB-RCS environment which is geared towards IP traffic. In this respect also arises the question of efficiency caused by the resolution of ATM cells or MPEG frames – the currently available media formats in DVB-RCS.

VoIP for SkyEdge

Going forward with a new access scheme provides an opportunity to resolve existing deficiencies in the model such as:

The transparency issue.interface to IMS.standardization of the protocol between

the NCC and the softSwitch.

5. Annex



VoIP for SkyEdge

ConclusionSatellite communications based on geo-synchronous satellites are

characterized by a large delay and high cost of resources. VoIP applications over satellite networks must thus be handled

very carefully so as to provide quality of service, as expected from voice calls while maintaining as high satellite resource exploitation efficient.

We have described above a circuit-switching approach to overcome the challenges VoIP posed to satellite network vendors and operators. The approach consists of an integrated softswitchincluded in the network, communicating with the hub and providing information for exact resource allocation such that each call isallocated dedicated resources.

The approach had been implemented and tested and is provided by Gilat and is commercially available as a VoIP solution.

Some considerations of using this approach in a DVB-RCS network were discussed and required additions to the standard were indicated.

The work of optimising VoIP and other session based protocols over the DVB-RCS standard was carried out under the VIVALDI project that is partially funded by the EC within the 6th FP.

VoIP for SkyEdge

Thank You

5. Annex



2.3 AUTh Presentation

Aristotle University of Thessaloniki

Performance Evaluation ofCRTP and Enhanced CRTP

within the DVB/RCS Context

Prof. F.-N. Pavlidou


Presentation Outline• Introduction• Header Compression schemes• Implementation Architecture• Evaluation Parameters• Evaluation Results• Conclusions

5. Annex




Introduction• Transition towards all-IP environments is

gathering momentum.• New operating modes simplify many issues, but

introduce some new ones.• In the case of VoIP, the overhead introduced by

the networking stack is comparable to the actualpayload.

• Header compression schemes are essential forthe reduction of the RTP/UDP/IP header size.


Header Compression• Requirements of Header Compression schemes

• Minimization of RTP/UDP/IP header size• Transparency• Minimal degradation of packet delivery ratios• Low complexity

• Available Header Compression Schemes forRTP traffic:• Compressed RTP (CRTP)• Enhanced CRTP• Robust Header Compression (ROHC)

5. Annex




Header Compression• CRTP reduces the header size by employing shared

information between the two peers (context).• Header field values that can be deduced from the context

are not communicated.• Differential encoding is used for well behaving fields.• Absolute values communicated only for volatile fields.• Recovery from desynchronisation is triggered by the

decompressor by sending a CONTEXT STATE packet.

• Enhanced CRTP adds an open loop desynchronisationavoidance mechanism, i.e. multiple transmissions ofcontext critical information.


Motivation• Existing work on header compression schemes

focuses on terrestrial (wireline, cellular) networks.

• Satellite environment poses different challenges:• Much longer delays• Packet Loss Rates higher than in wireline networks, but

lower compared to cellular ones.

• Our goal is to implement a modular testbed thatemulates the satellite environment.

5. Annex




Implementation Architecture• The netgraph framework on FreeBSD allows the

diversion/injection of traffic from the kernel touser land processes.

• Modules residing in user land form daisy chainseach modelling a different processing stage.

• Implementation is transparent to upper layers, offering flexibility regarding traffic generation(e.g. softphones, playback of traces…)


Implementation Architecture• Four modules currently available, more in

various stages of development.

delay: Delays and discards packets according to userdefined distributions (wireline part).

CRTP: compresses/decompresses packets according tothe Compressed RTP rules.

ECRTP: compresses/decompresses packets according tothe Enhanced CRTP rules.

sat_delay: Delays by a user defined distribution anddiscards (Markovian process) packets (satellite part).

5. Annex




Implementation Architecture


Evaluation Parameters• Delay module:

• Delay: Normal distribution with 30 ms mean and 3 ms standard dev.• Packet Loss: Binomial distribution with packet loss rate 0.5%

• Sat_Delay module:• Delay: Uniform distribution with 290 ms mean and 5 ms standard dev• Packet Loss: Markovian on-off process with the following intensities:

5. Annex




Evaluation Results

• Both schemes achievevery good compressionratios (> 89%).

• Enhanced CRTP does notperform as well as CRTP due to the multiple contextupdates.

• Rising trend in curves iscaused by the morefrequent desynchonisationoccurances as the errorintensity rises.


Evaluation Results

• Due to the multiple contextupdates, Enhanced CRTP performs better in terms ofpacket loss in all settings.

• As the error intensity rises, the loss of synchronisationbecomes more frequent.

5. Annex




Evaluation Results

• Histogram shows thenumber ofdesynchronisationoccurances vs the numberof packets lost per suchoccurance.

• Even though the packet lossrate is low, each desyncoccurance is destructive.

• ~600 ms worth of voice datais lost per such occurance.

• Desync is not very frequent: Worst case period is in theorder of 1 min for bothCRTP and ECRTP.


Conclusions• Header Compression is a necessity within the

DVB/RCS context.• Both CRTP and Enhanced CRTP showed very

good compression ratios.• Regarding robustness CRTP is more vulnerable

to channel impairments compared to EnhancedCRTP.

• The very long round-trip times highlight thedefficiencies of the triggering mechanism forrecovery from desync.

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