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DVB RCS Standards
&
Future Evolutions
Giovanni Garofalo
European Space
Agency
DVB-RCS Background
DVB-RCS defines a return
channel over satellite for
broadband systems based on
DVB-S(2) forward link
Specification initially defined by
satellite operators working under
the auspices of ESA
Work taken over by DVB Project,
which is responsible for standard
maintenance
ETSI approves its publication as
EN 301 790, according to their
defined procedures
Definition started in Sept 1997
Editions
•1st (v1.2.2)12/00
•2nd (v1.3.1) 03/03: RSAT
•3rd (v1.4.1) 09/05: DVB-S2
Open Standards Principles
Openness
All stakeholders participate in the standards development
process
Consensus
Due Process
All interests are discussed and agreement found
Open IPR
Holders of Intellectual Property Rights (IPR) must identify
themselves during the standards development process
Open World
Open Access
Same standard for the same function world-wide
Open Meeting
On-going Support
All may participate in standard development meetings
Open Interfaces
Open Use
Allow additional functions, public or proprietary
Balloting and appeal process may be used to find
resolution
Open access committee: documents, drafts and
completed standards
Standards supported until user interest ceases rather
than when provider interest declines
Low or no charge for IPR necessary to implement an
accredited standard
The case of DVB-RCS:
Open standard
Scrutinised, optimised, built by consensus
Based on commercial requirements
Broad range of services and applications
supported
Future-proof (e.g. DVB-S2)
Based on successful DVB-S
Availability of mass market low cost satellite
TV receivers
Enables interoperability between products
The case of DVB-RCS:
Multiple implementations
Several system integrators
Several terminal-only suppliers
Different choices of options and parameters
Several generations of system implementations
Cost & feature optimised
Enables interoperability between products
SatLabs Group basics
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Association set up to bring the DVB-RCS standard to largescale adoption
– Foster availability of interoperable products
– Ensure availability of solutions for interoperability testing and
certification
Membership open to all organizations worldwide interested in
the DVB-RCS standard
Main emphasis on interoperability but addressing other
aspects related to DVB-RCS implementation
Creation: October 2001
SatLabs Membership
Service
+ Access
Provider
Satellite
Operator
Satellite
Supplier
System
Supplier
Equipment
Supplier
Techno
Supplier
Avanti
Eutelsat
Alcatel
Alcatel
Alcatel Bell
AASKI
Aramiska
HellasSat
Astrium
EMS
NDSatcom
Invacom
FranceTelecom
Hispasat
Gilat
Thomson
Skyware
MonacoTelecom
JSAT
HNS
Spacebridge
Satlynx
NewSkies
Nera
STMicro
SESAstra
Newtec
Verisat
Telesat
Pentamedia
Visiosat
Shiron
ViaSat
DVB-RCS Standards
Overview
DVB-RCS Reference Diagram
SAT RT
SAT FW
DVB Forward
Link 2
DVB Forward
Link 1
RCST
Return Link
FEEDER 1
STATION
FEEDER 2
STATION
GATEWAY 1
STATION
RCST
GATEWAY 2
STATION
RCST
RCST
RCST
NETWORK 2
NETWORK 1
NCC
Interactive
Network
Adapter
Broadcast
Network
Adapter
Interactive
Service
Provider
Broadcast
Service
Provider
Network Control Centre: a NCC provides
Control and Monitoring Functions (CMF). It
generates control and timing signals for the
operation of the Satellite Interactive Network to
be transmitted by one or several Feeder Stations.
Traffic Gateway: a TG receives the RCST
return signals, provides accounting functions,
interactive services and/or connections to
external public, proprietary and private service
providers (data bases, pay-per-view TV or video
sources, software download, tele-shopping, telebanking, financial services, stock market access,
interactive games etc.) and networks (Internet,
ISDN, PSTN, etc.).
Feeder: a Feeder transmits the forward link
signal, which is a standard satellite digital video
broadcast (DVB-S or DVB-S2) uplink, onto
which are multiplexed the user data and/or the
control and timing signals needed for the
operation of the Satellite Interactive Network.
MAC Characteristics
Continuous Rate Assignment
Volume Based Dynamic Capacity
Rate Based Dynamic Capacity
Burst characteristics
Overhead Bursts
RCST
capa
Rand .
RCST
capa
Preamble
RCST
MAC
address
CSC
Route ID
Dynamic
Connectivity
Frequency
Hopping
Rand .
RCST
MAC
address
Rand .
CSC
Route ID
Rand .
Dynamic
Connectivity
Rand .
Frequency
Hopping
reserved
Rand .
reserved
encoded burst
SAC
SAC_lengthbytes
Randomized
SAC
Preamble
Preamble
Frequency sequence
encoded burst
Burst
type
identifier
Rand.
Burst
type
identifier
MF-TDMA
(Multi Frequency TDMA)
terminal 1
terminal 2
frame
terminal 3
Terminal architecture
USER
PC
IDU
TRANSCEIVER
INTERFACILITY
LINK
ODU
Interfacility Link: RX cable: FL signal on L-Band (950 – 2150 MHz)+ polarization control
+DC power (~10-20 volts) + to LNB (Low Noise Block) + 22 KHz tone (LNB
frequency band adjustment)
• TX cable: RT link L-Band TX (950-1450 MHz)+10 MHz reference signal to ODU
(BUC) + DC power to the BUC (20-30 volts) + 22 KHz PWK (Pulse Width Keying)
DiSEqC tone
DiSEqC (Digital Satellite Equipment Control): SSPA ON/OFF, TX frequency band
selection, …, ODU monitoring (SSPA status, PLL status, …)
Hub Architecture (1)
FLSS (Forward Link Subsystem)
•IP/DVB encapsulator
•Injects IP packets into
MPEG2/DVB compliant Transport
Stream
•MPEG2-DVB Multiplexer:
•Combines the MPEG Transport
Streams from the IP/Encapsulator
and the RLSS Controller/Scheduler
PCR Inserter
Generates a 27 MHz reference clock and
inserts relative time stamps in the FW link
for network synchronization.
DVB Modulator
Modulates the signal to IF frequency (Lband) according to the DVB-S or DVB-S2
standard
Hub Architecture (2)
RLSS (Return Link Subsystem)
•MCD (Multiple Carrier Demodulator):
•Demodulation of return path
carriers, De-Multiplexing of traffic
and Signaling
•Timing/frequency corrections
•Receiver Traffic:
•ATM recovery from Satellite cells.
•Interface with ISP through ATM
Switch
•Receiver Signaling:
•Forward received signaling to
Controller/scheduler.
•Control/Scheduler
Controls SITs entry and generates all
Satellite signaling on the forward path
•OAM (Operation, Administration and
Maintenance)
•Responsible for initializing,
configuring and monitoring all
RLSS functions to ensure proper
operation
Hub Architecture (3): IPSS
DVB-S versus DVB-S2
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DVB-S
Multiple streams: No
Input bit rate: fixed
Coding: Reed Solomon plus
convolutional encoding
Coding rates: ½, 2/3, ¾, 7/8
Input I/F: MPEG TS
Symbols mapping: Gray
Modulation format: QPSK
Pilot symbols: None
Symbols shaping: SquareRoot
Raised Cosine filter  =0.35
Transmission mode: constant
Coding and Modulation
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DVB-S2
Multiple streams: Yes
Input bit rate: variable frame-by-frame
Coding: BCH + Low-Density Parity
Check Codes (LDPC)
Coding rates: ¼, 1/3, 2/5, ½, 3/5, 2/3, ¾,
4/5, 5/6, 8/9, 9/10
Symbols mapping: BICM (Gray)
Modulation format: QPSK, 8PSK,
16APSK, 32APSK
Pilot symbols: Optional
Symbols shaping: Square-Root Raised
Cosine filter  =0.2, 0.25, 0.35
Input I/F: MPEG-TS, IP
Transmission modes: Constant Coding
and Modulation, Variable Coding and
Modulation, Adaptive Coding and
Modulation
DVB-S2/DVB-S Summary
 bit-rate gain (same C/N and symbol-rate):
25-35% depending on modes and applications
 Large flexibility to potentially match any
transponder characteristics:
 Spectrum efficiencies from 0.5 to 4.5 bit/s/Hz
 C/N range from –2.4 to +16 dB with 1 dB
granularity (AWGN)
0.7 – 1 dB from the Shannon limit probably means that:
“In the course of our lifetime we will never have
to design another system for satellite broadcasting”
Alternative
VSAT
Access Systems
IPoS: IP over satellite
• Originally published as TIA-1008,
now also co-published by ETSI
• Promoted by HNS
• Always-on IP service: once registered
the terminal does not need to ever
log-on again
• Protocol architecture separate
satellite-dependent functions and
satellite independent functions via
the SI-SAP interface positioned
between the MAC and Network
Layer. Elements above the SI-SAP
can be designed without knowledge
of the supporting satellite link layer
• Return link access similar to DVBRCS but with O-QPSK and variable
length bursts
• Support of contention-based access
DOCSIS-S
• Originally developed as terrestrial cable modem standard
• Promoted by ViaSat
• Consists of terminals (CM; Cable Modems) and Hub’s
(CMTS: Cable Modem Termination System)
• DOCSIS-S implements DOCSIS 1.1 above the PHY Layer
and a satellite specific PHY Layer
• Potential to save some costs on reuse of higher layer
components
• Benefits from the availability of a very mature sets of
infrastructure products for network control, system
management, subscriber management and billing systems
• FW link PHY based on turbo code with ACM (QPSK and
8PSK)
• MAC layer contains a 6 byte MAC header and a ETHERNET
packet as a payload. Encapsulation of IP packets requires
an additional 17 Bytes header and a CRC32
VIASAT SurfBeam System
• Telesat is using SurfBeam for consumer services in Canada on new
Anik F2 Ka-band, spot beam satellite
SurfBeam: ACM
Satcom Systems: comparison
DOCSIS vs. DVB-RCS
Future DVB-RCS Standards
Improvement Axis
Future Systems
83.33MHz
Return Uplink:
Polarisation
H
[29.916 ; 30] GHz
V
Return Downlink:
41.67MHz
[18.033 ; 18.2] GHz
V
166.67MHz
Based on WEB (West Early Bird) system design
H or V depending
on the beam where
the gateway is
located
Improved Coding Scheme
8PSK Modulation
6-bit quantization --- 8 iterations
10
10
k=1304 R=0.56597
k=1728 R=0.5
1
k=1504 R=0.65278
k=3008 R=0.65278
0,1
k=3008 R=0.52222
theoritical limit
FER
BER
BER
BER
BER
BER
FER
FER
1
FER
FER
FER
0,1
0,01
0,01
1E-3
1E-3
1E-4
1E-4
1E-5
1E-5
1E-6
1E-6
1E-7
1E-7
1E-8
1E-8
R=0.52222
R=0.5 k=3008
k=1728
1E-9
R=0.56597
k=1304
R=0.65278
k=3008
R=0.65278
k=1504
1E-10
1,5
2,0
2,5
3,0 EB/N0 3,5
4,0
4,5
1E-9
1E-10
5,0
8PSK
QPSK
Performance is improved by
as much as 1.2 dB!
Optimum bits-> symbol mapping strategy
 Several rates available
Preliminary Results
Fading Mitigation Techniques
Efficient FMT’s require the implementation of high order
modulations (8PSK and 16APSK)
Adaptive Coding and Modulation already successfully
implemented in the DVB-S2 FW link
FMT: ACM (Adaptive Coding and Modulation
Receive
d power
Transmitte
d power
Nominal
power target
ACM in the RT link
60% capacity increase!
FMT: DRA (Dynamic Rate Adaptation)
FMT: UPC (Upstream Power Control)
UPC case
Improvement Axis (2)
 Efficient Framing/Encapsulation: utilization of few
burst lengths, which are multiples of a basic slot size
Block length=188-bytes, PER=1e-6, AIPLEN=100 bytes, ATRAINLEN=500 bytes
7
DVB-RCS MPE/MPEG
Optimised Encapsulation and Segmentation
6.5
20% Efficiency gain
Energy per IP-bit/No (dB)
6
5.5
5
4.5
4
3.5
0.7
0.8
0.9
1
1.1
No. of IP-bits per channel symbol
1.2
1.3
1.4
 Continuous Phase Modulations for Return Channel:
Reduced complexity for receiver!
 Random Access together with DAMA:
Adapts very well to bursty type of traffic and to consumer user profile
ESA Strategy
for
DVB-RCS
ESA and DVB-RCS: Background
ESA has played a key role in the definition of
the DVB-RCS standard since its initial stages.
ESA actively supports the development of
DVB-RCS in the following areas:
 DVB-RCS standardization
 Technology R&D
 System R&D
 Application development
 Pilot projects
SatLabs Group
ESA fostered the creation of the SatLabs
Group and is leading its tasks
•
•
•
•
Ensure interoperability between DVB-RCS terminals and systems
Achieve low-cost implementations of DVB-RCS products
ESA is chairing the SatLabs Group
ESA leads most working groups and actively participates in the
technical tasks directly or through funded studies
• Key developments for the implementation of interoperability
verification are carried out by ESA
– Common Test Bed for interoperability testing
• ESA funds through ARTES lines key technological developments
needed to reduce DVB-RCS cost
– Low cost Components
– Low cost installation mechanisms
Applications
Applications are the bridge between the End User and the DVB-RCS
technology
ESA has developed and integrated DVB-RCS HW/SW elements and
contents under ARTES program in order to generate new applications
with commercial potential, and addressing the capability to provide the
applications in an Operational Context
• Supporting provision of Broadband Access Services through PILOT
projects: All activities involve a user community through a preoperational phase of actual utilisation of the system (e.g. Broadband in
the Sky, Pacific Skies, Inspire, SpaceforScience)
• Developing “Applications” suitable for DVB-RCS broadband access
services
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Telemedicine
Teleducation
Secure access
E-government
Infomobility
B2B
Budget evolution DVB-RCS R&D
ESA R&D Funding (MEur)
60
50
40
ARTES 5
ARTES 4
ARTES 3
30
ARTES 1
20
10
0
2001
2002
2003
2004
2005