CABSAT 2006Slide 1

Essentials of the DVB-RCS Standard

Prof. Gunnar StetteThe Norwegian University of Science and Technology

Representing ESA/ESTECas Chairman DVB-RCSG.Stette@iet.ntnu.no

CABSAT 2006Slide 2

The Essentials of DVB-RCSMember of a large family of standards, with strong industrial support

Add-on design for mass market broadcasting systems

Based on the DVB standards for the forward links

• DVB-S and DVB-S2 forward links

• Different DVB data profiles

Flexible system for data transmission

DVB-S2 with efficient modulation and coding system with Adaptive Coding and Modulation

Operation via satellites with on-board processing

Meshed (peer-to-peer) communications even with transparent satellites

Mobile applications

CABSAT 2006Slide 3

What is DVB, and how does it work?

•by the industry for the industry

•260 members•45 standards

CommercialRequirements

TechnicalExpertise

Consensus

CABSAT 2006Slide 4

A strong family of standards

• DVB-S (satellite) 1993– QPSK modulation with two layers of forward error

correction coding – Operate transponders of bandwidth 26 to 72MHz

• DVB-S2 (satellite) 2003– Multiple modulation- and coding methods– adaptive coding and modulation

• DVB-C (cable) 1994– 8MHz channel with 64QAM can give 38.5 Mbit/s– same signal format as for satellite ensures simplified

connection• DVB-T (terrestrial) 1995

– based onå Coded Orthogonal Frequency Division Multiplexing (COFDM)

– 2k & 8k modes (2000 eller 8000 carriers)• DVB-H (handheld)

CABSAT 2006Slide 5

DVB OVERVIEW

• About 120 million receivers deployed

• 90 million satellite, 17 million terrestrial

• DVB-T launched in 21 countries

• Standard adopted or pilot broadcasts in 35+ other countries

• More than 45 standards• Majority published by ETSI• Previously 7 of top 10 downloads

• More than 25 DVB-H trials

CABSAT 2006Slide 6

Adoption of DVB-S Satellite TV

CABSAT 2006Slide 7

The components of a TV program

Video-coder

Video-coder

Live pictures

Data,text

Data,text

Data

Serviceinformation

Data rate perTV-program

2 – 10 Mbit/s

Progra

m m

ultip

lexe

r

Two of the advantages

Flexibility

Efficiency

1,5 to 10 Mbit/s

Sound-coder

Sound-coder

Sound 64 to 192 kbit/s

Which is much less thanthe capacity of an analogTV broadcasting channel

CABSAT 2006Slide 8

Data streamsVideo-coder

Video-coder

Sound-coder

Sound-coder

Data,accesess ctrl.

Data,accesess ctrl.

Data strea perTV-program

Live pictures

Sound

Data

Serviceinformation

Serviceinformation

2 – 10 Mbit/s

• Packet transmission• Individually addressed• Encrypted

Video-coder

Video-coder

Sound-coder

Sound-coder

Data,accesess ctrl.

Data,accesess ctrl.

Data strea perTV-program

Live pictures

Sound

Data

Serviceinformation

Serviceinformation

2 – 10 Mbit/s

TR

AN

SP

OR

T M

ULTIP

LEX

ER

To broadcast channels

187 BYTES187 BYTES (3 HEADER + 184 DATA )SYNC1 BYTE 187 BYTES187 BYTES (3 HEADER + 184 DATA )SYNC1 BYTE

• Advanced technology• Mass produced,

consumer product

CABSAT 2006Slide 9

THE FORWARD LINK

BroadcastService

Provider

BroadcastNetwork Adaptor

FeederStation

Not only television, also

DATA BROADCASTINGAdvanced,

but affordableconsumerequipment

RCS uses DVB-S or DVB-S2as the forward link

CABSAT 2006Slide 10

DVB data profiles

Data

Audio

Video

TCP/ IP

Data Pipingasynchronous, non-synchronised, end-to-end delivery of data through DVB networks.

1 0 1 1 0 0 1 0 1 10 1 0 0 1 1 0 0 1 0

0 1 0 0 1 1 0 0 1 0

Data Streamingstreaming-oriented, end-to-end delivery of asynchronous, synchronous orsynchronised data through DVB networks

Multi protocol Encapsulationdata services that require the transmission of “datagrams” via DVB networks.

Data Carouselsdata services that require periodic transmission of data modules via DVB networks.

.dll.dl l

.doc

.pic.xls

CABSAT 2006Slide 11

The satellite system

BroadcastService

Provider

BroadcastNetwork Adaptor

FeederStation

Can be the same terminal

Advancedbut affordable

consumerequipment

GatewayStation

InteractiveNetwork Adaptor

InteractiveService

Provider

RCS uses DVB-S as the forward link

- and the satellite as the return link

CABSAT 2006Slide 12

Broadcast systems with interaction

AudioVideo

Software applicationsStill images

GraphicsDataText

Speech

TV receiverSet Top Box

Hi Fi SetGames Console

PDAPC

LaptopCommunicator

Broadcastchannels

Content Terminals

Interaction channels

DVB-CDVB-S

DVB-T DVB-H

GSMDECT etc.etc.

ISDNCable

GPRS

What about satellite?

CABSAT 2006Slide 13

Protocol model

Access mechanismPacket structure

Higher mediumlayers

Proprietary layers

Network DependentProtocols

Network IndependentProtocols

SynchronizationModulation

Channel codingFreq. Range

FilteringPower

(different for satellite, cable, terrestrial etc.)

DVBstandards

Slide 14

DVB-S modulation and coding

Un-coded, QPSK

Viterbi 7/8

Viterbi 3/4

Viterbi 1/2

Viterbi 7/8, 3/4 and1/2with Reed-Solomoncoding

Coding gain at 10-4 = 4.7 dB

CABSAT 2006Slide 15

Return Link Signal Format

Frequency

Time

Fixed-slotMF-TDMA

Frequency

Time

Optionaldynamic-slotMF-TDMA

MF-TDMA

Multi FrequencyTime Division Multiple AccessHigh utilization ofthe space segmentreturn channelThe symbol rate is not defined in the standard.

The time slots are organized and numbered in frames and superframesto obtain efficient signallingon the forward link

For simplified network operation

CABSAT 2006Slide 16

Capacity request categories

• Continuous Rate Assignment (CRA)– capacity negotiated between RCST and NCC

• Rate Based Dynamic Capacity (RBDC)– Dynamic request by RCST, with time-out

• Volume Based Dynamic Capacity (VBDC)– each request by RCST adds to earlier requested

• Absolute Volume Based Dynamic Capacity (AVBDC)

• Free Capacity Assignment (FCA)– capacity assigned to RCST from capacity otherwise

unused.

CABSAT 2006Slide 17

Conceptual RCST Architecture

Rxunit Tx unit

ODUOutdoor Unit

Networkinterface

unit

Userinterface

unit

Inter facility

link

IDUIndoor Unit

CABSAT 2006Slide 18

User interfaces

RCST ODU

RCST IDU/LAN Interface

Generic computer Generic computer

Generic computer Generic computer

Air interface

ATM

AAL5

IP

802.3

10 base T

RCST

802.3

IP

TCP/UDP

Appli

802.3

IPMPE

MPEG2-TS

DVB-S

Return link

Forward link

MPEG

MPE

10 base T

10 base T

CABSAT 2006Slide 19

0,00

0,50

1,00

1,50

2,00

2,50

3,00

3,50

4,00

4,50

-3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

R u[bi

t/s] p

er u

nit R

s

QPSK

8PSK

16APSK

32APSK

DVB-S

modulation constrained Shannon limit

18 dB

0.5 4.5

Capacity Capacity & & C/N requirementsC/N requirements

DVB-S2

0.7 – 1 dB from the Shannon limit

CABSAT 2006Slide 20

DVB-S2

DEMACM MOD

Return channel C/N+IMeasure

ment

bit-rate Control(trading useful bits

with FEC bits)

High protection

QPSK, RATE 1/2

Low Protection

8PSK rate 5/6

Potential ACM gain (ESA source): bit-rate x 2 in Ka band (Europe)DVB-S2-ACM gain versus DVB-S: bit-rate x 1.30 (FEC) x 2 (ACM)=2.6

FOR ONE-TO-ONESERVICES ONLY

ACM Adaptive Coding and Modulation

Source:Alberto Morello

CABSAT 2006Slide 21

DVB-S2 Generic Stream• The transmission is organised in FRAMES (train wagons)

Each frame transports a FEC CODE BLOCK (64800 bit) or (16200 bit). For Adaptive Coding and Modulation (ACM), protection may change frame-by-frame

Code Block HCode Block HCode Block H

FRAME

8PSK 5/6QPSK 2/316APSK 3/4 Source:Alberto Morello

CABSAT 2006Slide 22

Operation with regenerative satellites

NCC

Regenerative SAT

RSAT RSAT

NETWORK 1

GATEWAY 1STATION

NETWORK 2InteractiveNetworkAdapter

RSATRSAT

GATEWAY 2STATION

InteractiveServiceProvider

Control Plane NCC- RSAT signalling

NCC- SAT signalling

InteractiveNetworkAdapter

InteractiveServiceProvider

In The Control Plane each RCST communicates with NCC, Network Control Centre.

There is also signalling between the NCC and the satellite

CABSAT 2006Slide 23

User Plane

NCC

Regenerative SAT

RSAT RSAT

NETWORK 1

GATEWAY 1STATION

NETWORK 2 InteractiveNetworkAdapter

RSATRSAT

GATEWAY 2STATION

InteractiveServiceProvider

Point- To - Multipoint (monodirectional)

Point-To-Point (bidirectional)

User Plane

RSAT RSATRSAT

Multipoint -To-Multipoint (bidirectional)

Point- To - Point (monodirectional)

InteractiveNetworkAdapter

InteractiveServiceProvider

Point-To-Multipoint (mono directional)Point-To:Point (mono directional)Point-To:Point (bi-directional)Multipoint-To_Multipoint (bi-directional)

CABSAT 2006Slide 24

THIS IS NOW TESTED OUT

• IBIS project: Generic OBP-based interactive broadcast satellite system compliant with the DVB-RCS on the uplink and de DVB-S on the downlink

• AmerHis on the AMAZONAS satellite• Launched in August this year• Covers parts of Europe and South

America• Ku-band• In-orbit testing going on• Regenerative On Board Technology

(DVB-RCS / DVB-S)• Generation of the First Laboratory

Prototype• Successful Integration of Satellite

Traffic Models• IP Mesh Connectivity in a single Hop• Native MPEG-2 Contributions On Board

Multiplexing

CABSAT 2006Slide 25

FROM STAR TO MESH NETWORKS

The option of satellite on-board processingis already included in the RCS standard

Corporate

AccessControl

functions

RSAT

AccessNetwork

Management

ISP

MNMS/NCC

Traffic link

Signalling link

LAN

RSAT

RSAT

SatelliteOn Board Processor

(OBP)

CABSAT 2006Slide 26

MESH CONNECTIVITY

NCC RCST NCCRCST 2

RCST 1

LAN 1

LAN 2

PC 1

PC 2 LOGON 1

LOGON 2

TRAFFIC IP

TBTP

Animation: IBIS Project

CABSAT 2006Slide 27

Hub-Spoke and Peer-to-Peer

Source: Viasat

CABSAT 2006Slide 28

Mobile RCS

Aero mobile

Maritime mobile

Trains

CABSAT 2006Slide 29

DVB-RCS ON TRAINS

• Over trains, high-cost, directive antenna with mechanical tracking may be used (Ku-band reception)

• Strong variations of the signal power– Multipath fading (present, but negligible)– Signal shadowing (partial or total)

• Buildings• Trees• Bridges• Tunnels• Etc…

Source: Alberto Morello

CABSAT 2006Slide 30

-2.5 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 2.5-20

-15

-10

-5

0

5

Atte

nuat

ion

[dB

]

h [m]

Attenuation relative to an 0.4 m wide obstacle in Ku-bandLine-of-sight (few dB fading)rain (3-6 dB fading, few events

per years, duration of minutes) and scintillation

Non line-of-sight (deep fading)Short (tens of ms) periodicfading due to power supply catenariesMedium to long (tens of ms to

tens of s) Sporadic fading. Ruraland Suburban: foliage, bridges,..Very Long (few s to several

minutes) sporadic interruptions: tunnels, hills, houses

Terrestrial coverage:DVB-H

Wireless-LAN

Satellite coverage +Countermeasures

at system level

Channel model (Ku band, GEO)Channel model (Ku band, GEO)

Source: Alberto Morello

CABSAT 2006Slide 31

RCS AND MOBILITY

Radio frequency mattersKu-band is allocated to mobile on a secondary basisoff-axis EIRP is a major constraint when small antennas are considered ⇒ spectrum spreading

Physical layerRCS technology well adapted to low fading. For channels with high fading, shadowing, modifications will be requiredDVB-RCS covers most of the synchronization requirements in mobile environments Doppler compensation for aeronautical applications

Mobility managementDVB-RCS signaling provides enough support for mobilityInclusion of DVB-S2 provides a new frame for forward link handoverFurther considerations for return link handover

NOW BEING STUDIED BY THE RCS COMMITTEE

CABSAT 2006Slide 32

SUMMARY

The DVB family of standards, with strong industrial support, based on

mass market broadcasting systems

Flexible system for data transmission,

star and mesh networks

DVB-S2 with efficient modulation and coding system with

ACM (Adaptive Coding and Modulation)

Extension to mobile applications