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ATSC M/H Mobile Broadcast for Portable Services

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

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ATSC M/H Mobile Broadcast for Portable Services

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  1. ATSC M/HMobile Broadcast for Portable Services April 12 2008 Thomson/Micronas Joint Technology Proposal

  2. ATSC M/H Needs and System OverviewRich Citta

  3. Broadcaster Requirements • True Mobile service • Handheld device service • Backward compatible • Top 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 )

  4. Flexibility with Efficiency • Allows for Wide Range of Operating Points • Light mobile channels • Low rate single channel video • Data services • Heavy mobile channels • Multi-channel mobile video services • High resolution mobile video services • Dynamically changing mobile channels • Varying mixes according to changing programming block Maximum Efficiency of Spectrum Used Allows for a wide variety of business models

  5. Receiver MarketCell-phone

  6. Car TV

  7. Smart-phone

  8. Lap Top

  9. ATSC HDTV

  10. Receiver Markets • Cell-phones QVGA • Car – TV QVGA-VGA • Smart-phones VGA • Lap Tops SDTV • All ATSC receivers HDTV • Multi resolution system needed

  11. Receiver Environment

  12. Receiver Environment

  13. Receiver Environment

  14. Receiver Environment

  15. Receiver Environment

  16. Rayleigh Fading Channel

  17. Cellphone 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 Worse cast: Cellphone

  18. 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

  19. Diversity • Receiver Diversity For cars For laptop computers • Time Diversity For Handheld Receivers • Transmitter Spatial Diversity S F N • Transmitter Frequency Diversity Maximum over lapping coverage M F N • Transmitter Frequency & Spatial Diversity For shadowing due to hills

  20. Transmitter Spatial Diversity S F N

  21. Burst Mode Transmission • Allows for power efficient receivers • Power off receiver while waiting for data of interest • Multiple service tiers/power requirements in the same multiplex • Seamless MFN operation • Maximizes coverage throughout operating area • Supports current and future SFN and MFN operation Mobile Bursts Time Receiver Off

  22. Time Coded Diversity Block Coding Provides Maximum Diversity Capability R = 1/2 • Robust time-diverse • output • Each Burst independently decodable for deep fades • together they provide maximum threshold performance Data Burst coder Physical Layer Combiner Delay Buffer 8-10 Seconds!! Redundancy

  23. Coded Cooperative Transmitter Diversity M F N

  24. A Total Diversity Solution

  25. Receiver / Transmitter Diversity

  26. Channel 51 Sear Tower

  27. Channel 52 Sear Tower

  28. Channel 53 Hancock Tower

  29. Coded Cooperative Transmitter Diversity • 2nd Channel: Frequency Diversity • 2 Independently Fading Signals • Mitigates Deep Nulls & Fades • Improve Quality of Service or Boost Data Rate by more than 2

  30. Design Objectives for Mobile System • Spectrum is a limited asset with increasing value • Efficiency throughout the system • Flexibility • Broadcasters have diverse requirements and business models will vary considerably • Diversity • Time > 8 sec. To address pedestrian modes • Frequency For overlapping coverage

  31. Upper Layer Innovations:SVC and StaggerCastingDavid Campana

  32. CAS DRM Application Framework Video Codec(s )& Parameters Streaming Delivery File Delivery Audio Codec(s ) & Parameters Signaling Announcement Captioning Transport - M Image Formats Management Layer –Layers (S4-2) ATSC M/H Layers Presentation Layer - Media Formats (S4-3) Physical Layer –Layers (S4-1)

  33. Robustness in the Upper Layer • Technologies to improve the robustness (coverage and user experience) that are independent of the physical layer • S4-3 Presentation Layer • Scalable Video Coding • S4-2 Management Layer • StaggerCasting

  34. Scalable Video Coding – Motivation QVGA15 Hz SD 30 Hz SVC Encoder HD 60 Hz Widescreen

  35. Scalable Video Coding (SVC) • “Scalable Video Coding Extensions to H.264 AVC” • Adds an enhancement layer to the base H.264 AVC stream • Backward compatible with H.264 AVC • SVC base layer is playable by legacy H.264 player • Three types of scalability • Spatial (resolution) – most applicable to ATSC M/H • Temporal (time) • Fidelity (SNR)

  36. SVC – Encoder structure CIF source CIF AVCLayer SDSourceVideo Spatial Scaling AVCEncoding Packetizer Inter-layer prediction Bitstream SD SVClayer AVC-LikeEncoding

  37. Extended Spatial Scalability Base Layer Enhancement Layer • This example shows the use of SVC for • Upscaling to higher resolution • Cropping (narrow to widescreen adaptation)

  38. Additional Use Cases • SVC elegantly supports several interesting use cases which are difficult or impractical using traditional video compression

  39. Fast Channel Change • Encoder selects different GOP length for the base and enhancement layers • Short GOP in base layer for fast channel change • Long GOP in enhancement layer for bit rate efficiency

  40. SVC Value Proposition to ATSC M/H • Standard Evolution • Standard can evolve to higher resolution and quality without obsoleting current generation AVC only devices. • Graceful Degradation of Video Quality • If enhancement layer is lost, SVC decoder can decode base layer and upsample to conceal loss. • Efficient Simulcast • SVC is 10-30% more efficient than H.264 AVC simulcast at the exact same resolutions and encoder video quality settings.

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

  42. StaggerCast • Redundant stream sent in advance of the original stream • Adds significant time diversity (seconds) • Introduces no channel change delay • Operates at application level (ie. RTP in ATSC M/H)

  43. StaggerCast - Illustration Lost packets Stagger c d e f i j k l “c” = “C” A B C D G H I J Base time Recovered A B C D e f G H I J

  44. StaggerCast –Block Diagram Broadcast Terminal Stagger = original Delay Source (RTP stream) output (RTP stream) Stream Combiner Delay Base = Delayed original

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

  46. Channel Change Illustration Channel change c d e f r s t u v w Stagger Base A B C D P Q R S T U time Stagger stream protects from this point forward Terminal immediately plays new channel. Playback is not yet protected by stagger stream.

  47. StaggerCast Summary • Adds time diversity at application level • Doesn’t impact channel change • Optional tool for both receiver and broadcaster

  48. StaggerCast with SVC • StaggerCast and SVC benefit from each other • SVC improvement over AVC is more dramatic when base layer is protected more strongly • Minimized StaggerCast overhead by protecting only the critical elements of the stream • SVC base layer only • Audio

  49. SVC and StaggerCast Demo • Video: • 384x224 (widescreen) • 24 fps • IDR every 24 frames • Channel: • ATSC M/H approximation • 1 second burst losses • 10% packet loss

  50. SVC and StaggerCast Demo - Video AVC SVC and StaggerCast

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