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ATSC M/H Mobile Broadcast for Portable Services. April 12 2008. Thomson/Micronas Joint Technology Proposal. ATSC M/H Needs and System Overview Rich Citta. Broadcaster Requirements. True Mobile service Handheld device service Backward compatible Top 5 broadcasters in market - PowerPoint PPT Presentation

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  • ATSC M/HMobile Broadcast for Portable ServicesThomson/Micronas Joint Technology ProposalApril 12 2008

  • ATSC M/H Needs and System Overview

    Rich Citta

  • Broadcaster RequirementsTrue Mobile service Handheld device serviceBackward compatibleTop 5 broadcasters in market Program Full HDTV (14 mbits/s ) New services ( 5 mbits/s )Bottom 5 broadcasters in market Program SDTV ( 3 mbits/s ) New services (16 mbits/s )

  • Flexibility with EfficiencyAllows for Wide Range of Operating PointsLight mobile channelsLow rate single channel videoData servicesHeavy mobile channelsMulti-channel mobile video servicesHigh resolution mobile video servicesDynamically changing mobile channelsVarying mixes according to changing programming block

    Maximum Efficiency of Spectrum UsedAllows for a wide variety of business models

  • Receiver Market

    Cell-phone

  • Car TV

  • Smart-phone

  • Lap Top

  • ATSC HDTV

  • Receiver Markets

    Cell-phones QVGA Car TV QVGA-VGA Smart-phones VGA Lap Tops SDTV All ATSC receivers HDTV

    Multi resolution system needed

  • Receiver Environment

  • Receiver Environment

  • Receiver Environment

  • Receiver Environment

  • Receiver Environment

  • Rayleigh Fading Channel

  • Worse cast: CellphoneCellphone Antenna 10-15dB lost

    Height 1.5m 5-10dB lost

    In car speed 3-5dB lost

    In building 5-30dB lost

    Pedestrian waking into deep null 10-40dB lost

  • Lower Data Rates Needed R = 1/2 Th. 15dB 7.5 dB

    R = 1/3 Th. 5.0 dB

    R = 1/4 Th. 3.5 dB

    R = 1/6 Th 2.0 dB

    More improvement needed for worst case environment

  • Diversity

    Receiver Diversity For cars For laptop computers Time Diversity For Handheld ReceiversTransmitter Spatial Diversity S F N

    Transmitter Frequency Diversity Maximum over lapping coverage M F N

    Transmitter Frequency & Spatial Diversity For shadowing due to hills

  • Transmitter Spatial DiversityS F N

  • Burst Mode TransmissionAllows for power efficient receiversPower off receiver while waiting for data of interestMultiple service tiers/power requirements in the same multiplexSeamless MFN operationMaximizes coverage throughout operating areaSupports current and future SFN and MFN operationTimeMobile BurstsReceiver Off

  • Time Coded DiversityPhysical Layer CombinerDelay Buffer8-10 Seconds!!R = 1/2Robust time-diverse output

    Each Burst independently decodable for deep fades

    together they provide maximum threshold performanceRedundancy Burst coderData Block Coding Provides Maximum Diversity Capability

  • Coded Cooperative Transmitter DiversityM F N

  • A Total Diversity Solution

  • Receiver / Transmitter Diversity

  • Channel 51 Sear Tower

  • Channel 52 Sear Tower

  • Channel 53 Hancock Tower

  • Coded Cooperative Transmitter Diversity2nd Channel: Frequency Diversity

    2 Independently Fading Signals

    Mitigates Deep Nulls & Fades

    Improve Quality of Service or Boost Data Rate by more than 2

  • Design Objectives for Mobile SystemSpectrum is a limited asset with increasing valueEfficiency throughout the system

    FlexibilityBroadcasters have diverse requirements and business models will vary considerablyDiversityTime > 8 sec. To address pedestrian modesFrequency For overlapping coverage

  • Upper Layer Innovations:SVC and StaggerCasting

    David Campana

  • Management Layer Layers (S4-2)Physical Layer Layers (S4-1)Presentation Layer - Media Formats (S4-3)ATSC M/H Layers

  • Robustness in the Upper LayerTechnologies to improve the robustness (coverage and user experience) that are independent of the physical layerS4-3 Presentation LayerScalable Video CodingS4-2 Management LayerStaggerCasting

  • Scalable Video Coding MotivationQVGA15 HzSD 30 HzHD 60 HzWidescreenSVCEncoder

  • Scalable Video Coding (SVC)Scalable Video Coding Extensions to H.264 AVCAdds an enhancement layer to the base H.264 AVC streamBackward compatible with H.264 AVCSVC base layer is playable by legacy H.264 playerThree types of scalabilitySpatial (resolution) most applicable to ATSC M/HTemporal (time)Fidelity (SNR)

  • SVC Encoder structureSD Source VideoSpatial ScalingAVC EncodingAVC-Like EncodingPacketizerInter-layer predictionBitstreamCIF AVC LayerSD SVC layerCIF source

  • Extended Spatial ScalabilityThis example shows the use of SVC forUpscaling to higher resolutionCropping (narrow to widescreen adaptation)Base LayerEnhancement Layer

  • Additional Use CasesSVC elegantly supports several interesting use cases which are difficult or impractical using traditional video compression

  • Fast Channel ChangeEncoder selects different GOP length for the base and enhancement layersShort GOP in base layer for fast channel changeLong GOP in enhancement layer for bit rate efficiency

  • SVC Value Proposition to ATSC M/HStandard EvolutionStandard can evolve to higher resolution and quality without obsoleting current generation AVC only devices.

    Graceful Degradation of Video QualityIf enhancement layer is lost, SVC decoder can decode base layer and upsample to conceal loss.

    Efficient SimulcastSVC is 10-30% more efficient than H.264 AVC simulcast at the exact same resolutions and encoder video quality settings.

  • StaggerCast - MotivationMobile channels require significant time diversity for good performanceOther methods of adding time diversity (interleaving, long block codes) add unacceptable delay to channel change for the user.

  • StaggerCastRedundant stream sent in advance of the original streamAdds significant time diversity (seconds) Introduces no channel change delayOperates at application level (ie. RTP in ATSC M/H)

  • StaggerCast - IllustrationcdefijklABCDGHIJLost packetsc = CtimeABCDGHIJefStaggerBaseRecovered

  • StaggerCast Block Diagramoutput(RTP stream)Source(RTP stream)TerminalBroadcastStagger = originalDelayStream CombinerDelayBase = Delayed original

  • StaggerCast Channel ChangeStaggerCast does not add to channel change delay.On channel change:The receiver plays back base stream immediatelyThe receiver buffers the stagger stream.After stagger buffer is filled: The receiver can use the stagger stream to protect against loss.

  • Channel Change IllustrationcdefrstuvwABCDPQRSTUStagger stream protects from this point forwardChannel changeTerminal immediately plays new channel. Playback is not yet protected by stagger stream.timeBaseStagger

  • StaggerCast SummaryAdds time diversity at application levelDoesnt impact channel changeOptional tool for both receiver and broadcaster

  • StaggerCast with SVCStaggerCast and SVC benefit from each otherSVC improvement over AVC is more dramatic when base layer is protected more stronglyMinimized StaggerCast overhead by protecting only the critical elements of the streamSVC base layer onlyAudio

  • SVC and StaggerCast DemoVideo:384x224 (widescreen)24 fpsIDR every 24 framesChannel:ATSC M/H approximation1 second burst losses10% packet loss

  • SVC and StaggerCast Demo - VideoAVCSVC and StaggerCast

  • PHY Architecture

    Wen Gao

  • Outline of Thomson/Micronas PHY LayerOverview of PHY proposalImportant Features of PHY proposal No modification of the ATSC transmitter since all encoding is done at the transport levelSerial concatenated block code (SCBC)Flexible training data without trellis resetLow latency symbols Burst transmissionTransmitter diversity

  • ATSC MH Transmitter Proposal

  • Legacy ATSC Encoding RS codeDefined on a Galois Field GF(256)(K=187, N=207)Non-binary Linear systematic block codeAdding two code words produces a code wordMultiplying a code word by a field element produces a code word

  • ATSC MH Encoding SCBC codeNew non-binary linear Systematic block codeSerial concatenation of simple byte codes with byte interleaverByte Codes defined on same Galois Field as RS codeAchieve excellent performance with short block length26 bytes, 52 bytesAll encoding done at Transport level. Hence no modification of the transmitter Ensure fully backward compatible

  • Rate 1/2 Byte Code(N=2, K=1) byte code (GF(256) code)The information byte is mGenerator matrix is: G = (1, 2)The codeword is C = mG Note that all the operations are done in GF(256) fieldExample: m=(12), C= (12) (1, 2) = (12,24) m=(154), C= (154)(1,2) = (154, 41)

  • Rate 2/3 Byte code(N=3, K=2) byte code (GF(256) code)The Generator matrix is

    Example:

  • Byte Code Design OptimizationUse 4 PAM as an exampleUn-e

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