dvb-c2 technology overview - nccvcommercial requirement vkey features to physical layer vstream...

工業技術研究院Industrial Technology Research Institute

DVBDVB--C2 technology overviewC2 technology overview

工業技術研究院資通所

侯信安

[email protected]年5月18日

mailto:[email protected]

Copyright © ITRI 工業技術研究院2

AgendaAgendaq Introduce to second generation DVB broadcast

standardsv History & evolution v New features in second generation DVB broadcast standards

q DVB-T2 technology overview v Commercial requirement v Key features to physical layerv Stream distribution method & Aid for network optimization v Possible applied scenarios v Comparison and conclusions

q DVB-C2 technology overviewv Commercial requirement v Key features to physical layerv Impact on current systemv Possible applied scenarios v Comparison and conclusions


analogue remains while digital explodesanalogue remains while digital explodes

Source: Bart Brusse, “The DVB Project and DVB-C2 - An Introduction,” DVB-C2 Face-2-Face meeting, Denver, CO, 10 February 2010


mid term capacity shortages in many mid term capacity shortages in many marketsmarkets

Source: Bart Brusse, “The DVB Project and DVB-C2 - An Introduction,” DVB-C2 Face-2-Face meeting, Denver, CO, 10 February 2010


Commercial RequirementsCommercial Requirementsq Expected capacity shortage among several large

operators in 2011-2013 timeframeq DVB-CM-C2 process started September 2007v Definition of use cases for a new specificationv Extracting commercial requirements for specification

q Commercial requirements released early 2008v Optimize use of cable channels & use existing technologyv Increase capacity (min. 30%) & allow global implementation

modulation & FEC schemesv No backwards compatibility requirements, but no requirement for

changes in network architecture or channel characteristicsv Possibility to implement the new technology into EuroDOCSIS


DVBDVB--C2 Overall Schedules and MilestonesC2 Overall Schedules and Milestones

DVB-TM

DVB-CM

DVB-TM

Industry

CfT Specification

Call for Techno-logies

ChannelModel

Approval

CommercialRequirements

StudyMission

Approval

Approval

ImplementationGuidelines

ETSIPublic Enquiry

Chip Design

ETSI

Industry

Q1 Q2 Q4

2008

Q3Q4

2007

Q3Q2Q1 Q1 Q2 Q4

2009

Q3

2010

Q1

CPE DesignIndustry


DVBDVB--C2 documentsC2 documents


C2 Frame structureC2 Frame structure


C2 SystemC2 System

q Input pre-processor v Split TS/GS to PLPsv Extract common PLP from

TS/GS

q Input processing v Mode adaption v Stream adaption

Bit

Interleaved Coding &

Modulation

Data Slice + Frame Builder

OFDM

generation

TS or GSE inputs

Input

processing

C2 system DVB-C2 output


C2 Frame structure for 6/8 MHz C2 Frame structure for 6/8 MHz


Improving spectrum efficiencyImproving spectrum efficiency

DVB-CSingle carrier

DVB-C2Multiple Carrier

Loss due to guard band

Loss due to shaping filter

8 MHz

e.g.24 MHz

Φ(f)

Φ(f)

DVB-CSingle carrier

DVB-C2Multiple

Carrier

8 MHz

e.g.24 MHz

Φ(f)

Φ(f)

Interference:Narrow band: public service channelsBroadband: LTE (790-862)

Loss all 8 MHz BW

Loss interference BW only

Description Parameter Overhead

Single carrier Shaping filter

Roll-off factor. 0.15 for DVB-C

15 %

Guard interval 1/128 Preamble 1 symbol Pilot density 1/96

Multiple carrier (OFDM)1

Guard band 200 KHz

3.25 (+0.22) %

1 32 MHz bandwidth, e.g. 5 data slices of 6.4 MHz

Narrow Notch 25 KHz (current aircraft radio ) Overhead1

Single carrier

Forbid the whole occupied 8 MHz spectrum

25 %

Multiple carrier (OFDM)

Forbid only occupied spectr um 11 carrier s

≅1 %

1 32 MHz bandwidth, e.g. 5 data slices of 6.4 MHz


Notch in C2 FramesNotch in C2 Frames

time

time

Boar

d Ba

nd F

requ

ency

Not

ch

Narrowband notches

Broadband notches

Definition BW≤ 105 KHz BW> 105 KHz 1/64GI 11/ 23/ 35/ 47

carriers 11 carrier2 Bandwidth

1/128GI 23/47 carriers 23 carriers2 Notch position within a Data Slice

Yes No

Signaled in L1 Yes Yes Receiver handling Notch corrected

by L1 FEC Notch not inside tuning bandwidth

1 47 carriers at 8 MHz channel 2 minimum bandwidth no maximum, but one preamble adjacent to a Broadband notch


Tuner windowTuner window

q Preamble is mapped depending the center of the tuner window

q The tuner window does not contain any broadband notch to make the decoding of L1 part signaling successful

Data Slice 1

Data Slice 2

Data Slice 3

Data Slice 4

Data Slice 5

Data Slice 6

448

OFD

M S

ymbo

ls

Data Slice 1

Data Slice 2

Data Slice 3

Data Slice 4

Data Slice 5

Data Slice 6

448

OFD

M S

ymbo

ls Broadband N

otch


Absolute OFDMAbsolute OFDM

q The first L1 part 2 signalling block begins at the absolute frequency of 0 MHz

q Further blocks are partitioned in steps of 7.61MHz towards higher frequencies

q The pilot sequences of the OFDM signal are different for all different frequencies

q To avoid unwanted repetitions in the frequency domain which may cause unwanted high peak values of the OFDM signal in time domain

L1 Block L1 Block L1 Block L1 Block L1 Block L1 Block L1 Block

0 MHz

Frequency [MHz]

7.61 MHz

Actual DVB-C2 Signal

… …

Not Transmitted (virtual) L1 Data L1 Block

L1 Block Transmitted L1 Data


PLP bundlingPLP bundling

q If the data rate of a broadband PLP exceeds the capacity of a single Data Slice, it can be spread across different Data Slices

q A single PLP can therefore allocate arbitrary bandwidths up to the whole C2 system bandwidth

q Data Slice decoding on receiver side can be realized by v Multiple standard tuners (e.g. 8 MHz)v Broader tuner architectures


PLP BundlingPLP Bundling

DVB-C2 channel

2 21 4

MasterHE

IP-Backbone

OFDMModu-lator

StreamAdap-tion.

Data SlicingTim+Freq-Interl.

L1Configuration

DVB-C2-Phy(CCM)

1024 QAMCR=9/10

1024 QAMCR=9/10

1024 QAMCR=9/10

HFC



L1 block

Buf-fer

Buf-fer

Buf-fer

200Mbit/sdata stream(Internet)

Application example for PLP bundling; transmission of a high data rate MPEG2 transport stream via several bundled Data Slices in a DVB-C2 channel


Adaptive Coding and Modulation (ACM) Adaptive Coding and Modulation (ACM)

Low robustness, high efficiency(coding, modulation)

High robustness, low efficiency(coding, modulation)

100% high efficient Mod/Cod (CCM) (1024QAM, CR = 8/9)

100% robust Mod/Cod (CCM) (1024Q AM, CR = 3/4)

VCM/ACM with 50% robust Mod/Cod 50% high eff Mod/Cod

Data Rate (32 MHz C2 channel) 269.3 MBit/s 226.65Mbit/s 248 MBit/s


MasterHeadend

IP-Backbone

OFDMModu-lator

L1 configurationDVB-C2-Modulator (using GSE)

Stream Adapt. 1024QAM, CR=3/4 Data Slicing, Time+Freq.- Interleaving

Stream Adapt. 1024QAM, CR=3/4







Stream Adapt. 1024QAM, CR=8/9 Data Slicing, Time+Freq.- InterleavingStream Adapt. 1024QAM, CR=8/9

IPTV streams

For user outlets with CNR=29dB


ACM using Variable Coding and Modulation ACM using Variable Coding and Modulation (VCM) in the DVB(VCM) in the DVB--C2 Modulator C2 Modulator


64 QAMDVB-C

256 QAMDVB-C

PALsystemlevel

-6dB

1024 QAMDVB-C2

-6dB

4096 QAMDVB-C2

noise and intermodulation floor

Backoff

-12dB0dB

16K QAMDVB-C2Rev. ?16%

(+13.2 Mbit/s)To 4096 QAM

6dB

64K QAMDVB-C2Rev. ? 33%

(+26.4 Mbit/s)To 4096 QAM

12dB

PALAM/VSB

AnalogueTV

Signal Level

q DVB-C allows lower signal levels, related to PAL system levelv Low contribution to the intermodulation interferencev With long amplifier cascades downstream capacity is limited to about 4

Gbit/s due to upcoming intermodulation noise q DVB-C2 will increase this capacity to 6 Gbit/s according to

calculationsv For enhanced HFC networks up to 8 GBit/s seem to be feasiblev Highest spectrum efficiency 16k-/64-QAM in enhanced HFC networks for

further use

DVBDVB--C2, System Load ConsiderationsC2, System Load Considerations


OFDM parametersOFDM parametersParameter "6 MHz"

1/64 "6 MHz"

1/128 "8 MHz"

1/64 "8 MHz"

1/128 Number of OFDM carriers per L1 Block KL1 3 408 3 408 3 408 3 408

Bandwidth of L1 Signalling Block (see note) 5,71 MHz 5,71 MHz 7,61 MHz 7,61 MHz

Element Period T µs 7/48 7/48 7/64 7/64 Duration TU 4096T 4096T 4096T 4096T Duration TU µs (see note) 597,3 597,3 448 448 Carrier spacing 1/TU (Hz) (see note) 1 674 1 674 2 232 2 232 Guard Interval Duration ∆/Tu 64T 32T 64T 32T Guard Interval Duration ∆/Tu µs (see note) 9,33 4,66 7 3,5 Frame Duration TF ms (see note) 271.8 269.7 203.8 202.2 NOTE: Numerical values in italics are approximate values.

Ndata Symbols

Guard Interval

Ndata Duration (ms)

TI MODE Npreamble symbols

% preamble overhead

Nsymbols in Frame

Frame Duration (ms)

448 1/128 202.3 00, 01 1 (min.) 0.22 449 202.7 448 1/128 202.3 00, 01 7 (max.) 0.54 455 205.4 448 1/128 202.3 10 4 0.88 452 204.1 448 1/128 202.3 11 8 1.75 456 205.9 448 1/64 203.8 00, 01 1 (min.) 0.22 449 204.3 448 1/64 203.8 00, 01 7 (max.) 0.54 455 207.0 448 1/64 203.8 10 4 0.88 452 205.7 448 1/64 203.8 11 8 1.75 456 207.5

Frame duration in DVB-C2


DVBDVB--C2 C2 v.sv.s. DVB. DVB--CCq DVB-C2 performance is close to the theoretical limitq Increased robustness:7 dBq Increase of spectral efficiency: 35 %q Gain of spectral efficiency in modern HFC networks: 60 %

DVB-C2 parameters: 32 MHz signal bandwidth, Guard Interval 1/128, pilot density 1/96


Echo Echo

IEEE 802.14

Time delay (ns)

IEEE 802.14

Time delay (ns)

Length segment [m] 250 50 10 2

Frequency [MHz} 140 800 140 800 140 800 140 800

Reflection loss (2x) [dB] 36 20 36 20 36 20 36 20

Attenuation @ 3dB/100m (200MHz) [dB] 15 30 3 6 0,6 1,2 - -

Total Loss [dB] 51 50 39 26 37 21 36 20

Delay [ns] 2500 500 100 20


q The intermodulation products can be distinguished in three types v Narrow band intermodulation products, the CSO and CTB cluster

beatsv Broadband, random noise-like intermodulation productsv Impulse noise

Nonlinear behaviour of components Nonlinear behaviour of components

CSO: Composite Second Order (2nd order component) CTB: Composite Triple Beat (3rd order component)


The effect of DVBThe effect of DVB--C2 carrier levelC2 carrier level

Carrier signal level [dBµV]100 105 110 115 120

CIN

R/ M

ER [d

B] 55

50

40

45

CIN

R/ M

ER [d

B] 55

50

40

45

-9

-4

-5

-6

-8

-7

-9

-4

-5

-6

-8

-7

LOG

(BER

)

• random IM noise• impulse noise• cluster beats• thermal noise

• cluster beats• thermal noise

A C

BERAWGN

BERMeasured

(random IM noise) cluster beats

thermal noise

•••

B


IntermodulationsIntermodulations

Output level (dB)0 10 20

Hybrid 2

CIN

R(d

B)

measurementsimulation


Hybrid 1

CIN

R(d

B)


Output level (dB)0 10 200 10 20

Hybrid 2

CIN

R(d

B)

measurementsimulationmeasurementsimulation


Hybrid 1

CIN

R(d

B)



Hybrid 1

CIN

R(d

B)


Output level (dB)0 10 200 10 20

Hybrid 1

CIN

R(d

B)


CTBCSO

CIN

R(d

B)


Output level [dBµV]

CIN

R(d

B)



Hybrid 2

Output level (dB)0 10 20 30


Hybrid 2

CTBCSO

CIN

R(d

B)



CIN

R(d

B)



Hybrid 2



Hybrid 2

CIN

R(d

B)



CIN

R(d

B)



CIN

R(d

B)



Hybrid 2

Output level (dB)0 10 20 300 10 20 30

Output level (dB)0 10 20 300 10 20 30

Hybrid 2

f1: 119 MHz f2: 420 MHz f3: 855 MHz

96 digital carriers

42 unmodulated carriers


The effect of DVBThe effect of DVB--C2 carrier levelC2 carrier levelq Network load

in this example:v 20 aTVv 30 QAM/DOCSISv 43 DVB-C2v 8 MHz grid

q Requirements:v 7 dB implementation marginv Analog TV does not exceed IEC quality requirements for noise and

intermodulationq Results:v DVB-C2 transmission of constellations up to 4096-QAM supported by cable

networks with a margin of some 5 to 6 dB in N+15 scenariosv All digital based on DVB-C2 (4096-QAM) may be critical in some networks

Source: Dirk Jaeger, “DVB-C2 system aspect,” CableLabs winter Conference, Denver CO, 19 February 2010


Efficient signal conversion from satellite or Efficient signal conversion from satellite or terrestrial link to DVBterrestrial link to DVB--C2 C2

1

2

6

OFDMModu-lator

DVB-S2-Frontend

DVB-S2Frontend.

L1 Co nfiguration

PSI/SIStuffin g

PSI/SIStuffin g

DVB-C2-ModulatorMPEG2-TS-Processing

DVB-S2-Recei-ver

StreamAdapt.

DVB-S2-Frontend

Data SlicingTime+ Freq-Interleaving

PSI/SIStuffin g

1024QAMCR=9/10

StreamAdapt.

1024QAMCR=9/10

StreamAdapt.

1024QAMCR=9/10

2 31 54 6



HFC

Data Slice 1..4 42.66Mbit/sData Slice 6 49.39Mbit/s

Total 269.44Mbit/s

L1 block

1

2

6

OFDMModu-lator

DVB-S2-Frontend

DVB-S2Frontend.

L1 Co nfiguration

PSI/SIStuffin g

PSI/SIStuffin g

DVB-C2-ModulatorMPEG2-TS-Processing

DVB-S2-Recei-ver

StreamAdapt.

DVB-S2-Frontend


PSI/SIStuffin g

1024QAMCR=9/10

StreamAdapt.

1024QAMCR=9/10

StreamAdapt.

1024QAMCR=9/10

2 31 54 6



HFC

Data Slice 1..4 42.66Mbit/sData Slice 6 49.39Mbit/s

Total 269.44Mbit/s

L1 block

Satellite transponders DVB-C2 channel Transponders 6 Data Slices 6 Transponder bit rate 4*?42.66 2*49.39 Slice bit rate (Mbit/s) 4*42.66 2*49.39 Transponder bandwidth (MHz)

5?27 33 Total C2 channel bit rate (Mbit/s)

5?42*66 +1?49.39 = 269.44

Modulation 8PSK QPSK C2 channel bandwidth (MHz)

32

Code rate 2/3 9/10 Modulation (CCM) 1024QAM 1024QAM Symbol rate 22 27.5 Code rate 9/10 9/10

DVB-C2 channelBW=32 MHz


Coding and modulation on Service Level Coding and modulation on Service Level ““Low Power ModeLow Power Mode”” in in CPEsCPEs

IP Back-bone

OFDMModu-lator

L1 configurationDVB-C2-Phy , (CCM/VCM)

HFCStream Adapt.

Stream Adapt.

1024QAM, CR= 9/10

16QAM, CR=3/4

Stream Adapt.

Stream Adapt.

1024QAM, CR= 9/10

1024QAM, CR= 9/10

Data SlicingTime+Freq-Interleaving

Data SlicingTime+Freq-Interleaving

SPTS streams(MPEG2-TS)

DVB-C2 channel

L1 blockDataSlice widthvariable(VBR)

Stuffing data Slice(s)for constant overall datarate

Stream Adapt. 16QAM, CR=3/4MPEG2-TS

Demux

PSI/SI-Generation

DVB-T/T2Frontends

IP-Gateway

DVB-S/S2Frontends

Aux FEC/ModAux Data

CPLP Slice

MPTS streams(MPEG2-TS)

Common PLP (CPLP)

CPLP SliceStuffing Slice


Interactive service transmissionInteractive service transmission

DVB-C2Mod

DVB-C2Mod

DocsisModem

DOCSISModem

STBDocsis Core

CMTSDocsis Core

CMTS

GigEBackbone

(IPTV, VoIP,Internet)

IP/MPEG2-TS

Remux

MPEG2-TSVODTV (SDV)

STB

IP/GSE

HFC Downstream

HFC Down-Stream (IP)

HFC Upstream

HFC UpstreamIPTV, Internet, VoIP,Other IP services…

MasterHeadendMaster

Headend

VOD

Parameter Value Comment OFDM carrier spacing 1/448us Due to 8 MHz channel raster Dx 24 OFDM carriers Due to GI = 1/128 Number of OFDM carriers 14160 Within the 32 M Hz C2 channel Start fr equency [MHz] 306.16 MHz Multiple of OFDM carrier spacing and Dx raster Number of carriers, bandwidth Data slice 1 (8 PLPs) Data slice 2 (8 PLPs) Data slice 3 (8 PLPs) Data slice 4 (8 PLPs)

Carr. Number 2424(t1), 3384(t2) 3384(t1), 2904(t2) 2904(t1), 2904(t2) 3384(t1),2424(t2)

Bandwidth [MHz] 5.41(t1); 7.55(t2) 7.55(t1); 6.48(t2) 6.48(t1); 6.48(t2) 7.55(t1); 5.41(t2)

Data rates [Mbit/s] Video group 1: 46(t1); 64(t2) Video group 2: 64(t1); 55(t2) Video group 3: 55(t1); 55(t2) Video group 4: 64(t1); 46(t2)

Data slice 5 (2 PLPs) 2064(t1); 2592(t2) 4.61(t1); 5.79(t2) Data group: 40.3(t1); 49.3(t2) One high speed Internet Service

Data Slice tuning positions [MHz] Data Slice 1-4

309.32 ; 315.64 ; 321.96 ; 328.29; 334.61

Equidistant distribution within the C2 channel

8 MPEG4 AVC Videos in each Video Group (6 x HD 10Mbit/s and 2 x SD 2Mbit/s)

DOCSIS: Data Over Cable Service Interface SpecificationCMTS: cable modem termination system


PLP BundlingPLP Bundling

DVB-C2 channel

2 21 4

MasterHE

IP-Backbone

OFDMModu-lator

StreamAdap-tion.


L1Configuration

DVB-C2-Phy(CCM)

1024 QAMCR=9/10

1024 QAMCR=9/10

1024 QAMCR=9/10

HFC



L1 block

Buf-fer

Buf-fer

Buf-fer

200Mbit/sdata stream(Internet)

Application example for PLP bundling; transmission of a high data rate MPEG2 transport stream via several bundled Data Slices in a DVB-C2 channel


MasterHeadend

IP-Backbone

OFDMModu-lator

L1 configurationDVB-C2-Modulator (using GSE)









Stream Adapt. 1024QAM, CR=8/9 Data Slicing, Time+Freq.- InterleavingStream Adapt. 1024QAM, CR=8/9

IPTV streams



ACM using Variable Coding and Modulation ACM using Variable Coding and Modulation (VCM) in the DVB(VCM) in the DVB--C2 Modulator C2 Modulator


Physical parameter comparisons Physical parameter comparisons between DVBbetween DVB--CC and DVBand DVB--C2 C2

DVB-C DVB-C2 Bandwidth (MHz) 6, 8 8~450, 6~338

Mode Constant Coding & Modulation

Variable Coding & Modulation

Modulation Single Carrier Multiple Carrier (4K)

Constellation 16, 32, 64, 128, 256-QAM 41, 16, 64, 256, 1024, 4096-QAM

FEC RS LDPC + BCH

Code rate N. A. 1/2, 2/3, 3/4, 4/5, 5/6, 8/9, 9/10

Interleavers Time Bit, Time, Frequency

GI N. A. 1/128, 1/64 Pilot N. A. Scatter, Continual, Edge 1 For use in Modulation for FECFrame Header and Preamble Header


Capacity comparisons of DVBCapacity comparisons of DVB--C & DVBC & DVB--C2C2

DVB-C DVB-C2 DVB-C2 64-QAM 256-QAM 1024-QAM 256-QAM Guard Interval NA 1/128 1/128 FEC RS 9/10 LDPC + BCH 5/6 LDPC + BCH Symbol rate 6.875 MBaud NA NA Bandwidth 8 MHz 8 MHz 8 MHz SNR 29,7 dB 29.5 dB 22 dB 2 Capacity 50.87 Mbit/s 66,14 Mbit/s 1 49.01 Mbit/s NOTE 1: The relative capacity gain is 30,5% at a SNR of 29,7 dB (required for 256-QAM DVB-C) NOTE 2: The relative robustness gain is 25,9 % at 50 Mbit/s payload (as provided by 256-QAM DVB-C)

DVB-C (256-QAM) DVB-C2 (4096-QAM) 8 MHz channel 50,9 Mbit/s 79,39 Mbit/s 16 MHz channel 50,9 Mbit/s 81,40 Mbit/s, 2,46%* 24 MHz channel 50,9 Mbit/s 82,08 Mbit/s, 3,41%* 32 MHz channel 50,9 Mbit/s 82,42 Mbit/s, 3,84%* 64 MHz channel 50,9 Mbit/s 82,93 Mbit/s, 4,49%* * relative gain with reference to 4096-QAM in 8 MHz bandwidth

Further improvements of spectrum efficiency due to increased transmitter bandwidth

Potential capacity or robustness increase of DVB-C2 in relation to 256-QAM DVB-C


ConclusionsConclusionsq Better performance v Increased throughput: 30% gain at SNR=29 dB v Increased robustness: 7dB less SNR at 50 Mbps throughput v Spectrum efficiency is 10.4 bps/Hz at most Ø 4096-QAM, 9/10, GI=1/128, 1 preamble, single PLP and single DS

q Data Slices for increased flexibilityv Flexible Data Slices combined to overall bandwidthv PLP bundling for big data pipes

q Notching for efficient interference mitigationq Variable & Adaptive Coding and Modulation for

best possible spectrum deploymentq C2 opens a new era that needs a lot of

modification of regulationsv e.g. Frequency allocation


References References q Bart Brusse, “The DVB Project and DVB-C2 - An Introduction,”

DVB-C2 Face-2-Face meeting, Denver, CO, 10 February 2010q Dirk Jaeger, “DVB-C2 system aspect,” CableLabs winter

Conference, Denver CO, 19 February 2010q http://dvb.org/technology/dvbt2/index.xml

http://dvb.org/technology/dvbt2/index.xml

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