tsg-c swg1.2 ad hoc, montréal, québec c12-20040517-012 1 of 40 video delivery in cdma2000®...

TSG-C SWG1.2 Ad hoc, Montréal, Québec C12-20040517-012 1 of 40

Video Delivery in cdma2000® Networks

Hari Garudadri [email protected] Phoom Sagetong [email protected] Nik Leung [email protected]


NoticeQUALCOMM Incorporated grants a free, irrevocable license to 3GPP2 and its Organization Partners to incorporate text or other copyrightable material contained in the contribution and any modifications thereof in the creation of 3GPP2 publications; to copyright and sell in Organizational Partner’s name any Organizational Partner’s standards publication even though it may include portions of the contribution; and at the Organization Partner’s sole discretion to permit others to reproduce in whole or in part such contributions or the resulting Organizational Partner’s standards publication. QUALCOMM Incorporated is also willing to grant licenses under such contributor copyrights to third parties on reasonable, non-discriminatory terms and conditions for purpose of practicing an Organizational Partner’s standard which incorporates this contribution.This document has been prepared by QUALCOMM Incorporated to assist the development of specifications by 3GPP2. It is proposed to the Committee as a basis for discussion and is not to be construed as a binding proposal on QUALCOMM Incorporated. QUALCOMM Incorporated specifically reserves the right to amend or modify the material contained herein and nothing herein shall be construed as conferring or offering licenses or rights with respect to any intellectual property of QUALCOMM Incorporated other than provided in the copyright statement above.


Abstract & Recommendation

• This contribution presents an approach to deliver video content efficiently over cdma2000 wireless channels

• Explicit Bit Rate Control (EBR), matches encoder packet sizes to physical layer packet sizes

• EBR benefits include – Improved Error Resiliency– Lower latency– Ability to strip IP headers

• Video codec modifications are completely “Standards Compliant”; Other changes include

– Rate control at the encoder– QoS support for synchronous video packet delivery in a particular

window– Header Compression support at the PDSN (header removal or

compression)• Recommendation

– Review and adopt


Overview

• VBR encoding for CBR Delivery• EBR restrictions on rate control

– cdma2000 provides VBR channels with “Explicit Rates”– Simulation results demonstrate compression efficiency

comparable to true VBR• Error Resiliency

– Improved resilience to channels errors– Simulations demonstrate quality improvements

• Lower Latency– QoS constraint on delay– Enables lower latency with EBR rate control

• Header Compression– EBR supports header removal– Other header compressions schemes also supported


VBR Encoding for CBR Delivery


Anatomy of a Video frame

SC FH Video_packet(1) RM

Video_packet(2)

RM Video_packet(3)

RM Video_packet(n)

SC = start_codeFH = frame_headerRM = resync_marker


VBR Sources on CBR Channels

• Video is inherently a VBR source• Delivery of a VBR source over a CBR channel requires traffic shaping

Carphone Qp=15(MPEG-4);33(H.264)

0

500

1000

15002000

2500

3000

3500

4000

1 10 19 28 37 46

Frame Number

Size

in B

ytes

MPEG-4H.264


VBR encoding on CBR

EncoderBuffer

Video Frame index

Size Size

Phy. layer Frame index

Channel


Buffer Delay

MPEG-4 Transmission Example (64kbps)

0

5000

10000

15000

20000

25000

30000

35000

40000

0 10 20 30 40 50 60

Frame Number

Byt

es (c

umul

ativ

e)

Source

Transmission

Display

• MPEG-4 SPL0 with Qp = 15, 64kbps on 64kbps channel• Buffer delay of 1 second (10 frames in buffer, to prevent underflow)


VBR Channels?

• What if the Channel is capable of variable rates?– Similar to FCH, but with higher rates– Higher rates can be used for I frames and dtx’ed for P frames

• What if the Encoder is capable of generating Video Slices accordingly?


MS

BSC/PCF PDSNInternet

FCHDCCHSCHPDCH RAN TCP/IP

RTP/RTCPRTSP

Wireless Network Architecture

Generic wireline to wireless communication diagram

• FCH: Variable rate channel in RS-1 and RS-2; used mainly for voice• DCCH: Constant rate channel in RS-1 and RS-2• SCH: High rate channel; Shared in TDM• PDCH: High rate channel; Fast allocation among many users; uses hybrid

ARQ


EBR Restrictions on Rate Control


EBR: SCH Constraints

• Constant frame rate (10 fps, 15 fps, …)• DTX, DCCH, SCH, DCCH+SCH for each 20 ms slot• 4 rates result in a spectrum of 20 unique options for slice

sizes in one frame– One Video frame every 100 ms: Up to 5 slices per frame– Two Video frames every 200 ms: Up to 9 slices per frame

• DCCH = {9.6, 14.4} based on the radio configuration (RC)• SCH = {n * 9.6, n * 14.4} based on RC; n={1, 2, 4, 8, 16}

41 2 3 520 ms

dtxDCCHSCH

DCCH+SCH4 possible rates each 20 ms


SCH + DCCH Packet Sizes

Video Slice Sizes DCCH Configuration SCH Configuration

1 20, 40, 60 RS1 2x in RC3

2 20, 80, 100 RS1 4x in RC3

3 20, 160, 180 RS1 8x in RC3

4 31, 40, 71 RS2 2x in RC3

5 31, 80, 111 RS2 4x in RC3

6 31, 160, 191 RS2 8x in RC3

7 20, 64, 84 RS1 2x in RC5

8 20, 128, 148 RS1 4x in RC5

9 20, 256, 276 RS1 8x in RC5

10 31, 64, 95 RS2 2x in RC5

11 31, 128, 159 RS2 4x in RC5

12 31, 256, 287 RS2 8x in RC5


PDCH Packet Sizes

F-PDCH (BYTES) R-PDCH (BYTES) R-PDCH STUFFING BITS

360 (45) 360 (45) 0

720 (90) 720 (90) 24

1440 (180) 1440 (180) 72

2880 (360) 2880 (360) 168


EBR: PDCH Constraints

• Constant frame rate (10 fps, 15 fps, …)• n Video frames every nT ms, T = 1000/frames_per_second• Video slices are fixed in size (e.g. 90 bytes)• Variable number of slices per frame

– I frames need ~5 to 8 more slices than P frames– Number of frames depends on the source characteristics


VBR: source distribution

VBR: Slice size distribution

0500

10001500200025003000350040004500

1 2 3 4 5 6

Frame Index

Byt

es


EBR – SCH+DCCH: source distribution

EBR-SCH/DCCH: Slice size distribution

0

500

1000

1500

2000

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3500

4000

4500

1 2 3 4 5 6

Frame Index

Byt

es


EBR – PDCH: – source distribution

EBR-PDCH

0

500

1000

1500

2000

2500

3000

3500

4000

4500

1 2 3 4 5 6

Frame Index

Byt

es


EBR Performance Comparison

• No loss in compression efficiency due to EBR constraints• Significant improvements under channel errors• VBR: If Packet I is lost, both Packets 1 and 2 are lost

– Packet Error Rate = (1 + m) FER – where m=avg. # frames per packet, FER = frame error rate of PHY

• EBR: Packet loss is restricted to one slice– Packet Error Rate = FER

Physical Layer Packets: Packet A ... Packet I

Application Packets: Packet 2 Packet 1 ...


EBR Vs VBR : Foreman

30.00

31.00

32.00

33.00

34.00

35.00

36.00

37.00

40.00 45.00 50.00 55.00 60.00 65.00 70.00 75.00 80.00 85.00 90.00

Bitrate (kbps)

PSN

R (d

B)

foreman VBR cleanforeman VBR noisyforeman EBR12 cleanforeman EBR12 noisy

1% Packet Loss, most of the errors in the beginning


EBR Vs VBR : Carphone


34.00

34.50

35.00

35.50

36.00

36.50

37.00

37.50

38.00

38.50

39.00

40.00 45.00 50.00 55.00 60.00 65.00 70.00 75.00 80.00 85.00 90.00

Bitrate (kbps)

PSN

R (d

B)

carphone VBR cleancarphoneVBR noisycarphone EBR12 cleancarphone EBR12 noisy


EBR Vs VBR : Stefan


24.00

25.00

26.00

27.00

28.00

29.00

30.00

40.00 50.00 60.00 70.00 80.00 90.00 100.00 110.00

Bitrate (kbps)

PSN

R (d

B)

stefan VBR cleanstefan VBR noisystefan EBR12 cleanstefan EBR12 noisy


EBR Vs VBR : News


32.00

33.00

34.00

35.00

36.00

37.00

38.00

39.00

40.00 45.00 50.00 55.00 60.00 65.00 70.00 75.00 80.00 85.00

Bitrate (kbps)

PSN

R (d

B)

news VBR cleannews VBR noisynews EBR12 cleannews EBR12 noisy


Latency Revisited


Video Delays

Encoder Channel Decoder

De DdDbDb Dt

• Buffers at Encoder and Decoder are of same size

• Total delay due to buffering is Db


Buffer Delay

MPEG-4 Transmission Example (64kbps)

0

5000

10000

15000

20000

25000

30000

35000

40000

0 10 20 30 40 50 60

Frame Number

Byt

es (c

umul

ativ

e)

Source

Transmission

Display

• MPEG-4 SPL0 with Qp = 15, 64kbps on 64kbps channel• Buffer delay of 1 second (10 frames in buffer, to prevent underflow)


Delay Considerations (Revisited)

• When Channel rate is exactly matched to encoder output, buffer delay is zero

H.264 Transmission Example (64kbps)

0

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15000

20000

25000

30000

35000

40000

45000

0 10 20 30 40


Delivery in PDCH

• 14 users, with 300 ms (n=3) max delay per user

0

100000

200000

300000

400000

500000

600000

700000

0 5 10 15 20 25 30 35 40 45 50

Tick

Byt

es

SourceTransmissionDisplay


Header Compression


Protocol Stack : Data Services

Traditional Wireless IP Protocol Stacks

• Basis for streaming and conversational services in 3G• Header compression/removal is required for efficiency

RTP

MAC

GRE

IP IP

GRE

IP

UDP

RTP

Application

MAC

MS BS/PCF PDSN Host

UDP

IP

Application


Protocol Stack : VoIP

Protocol Stack for Header Removal (SO60) in cdma2000

• Application (codec) talks directly to the MAC• PDSN performs IP Gateway function between VoIP and circuit-switched

voice over the air to provide improvement in radio efficiency• Air interface efficiency is same as that for CS domain (send minimum bits

required OTA)

BS PDSN

IP

GRE

IP

GRE

IP

GRE

HRUIP

CDMA2000 MAC

HRL

IP

GRECDMA2000 MAC

HRL

HRU (Codec)

PCFMS


Wireless IP Layers

...

RTP

PPP IP

UDP

RLP

Payload

One Physical Layer Frame

Codec

RTP

UDP

PPP

RLP

MUX

Physical Layer

RTP SH Payload

SH Payload

SH Payload

UDP RTP SH Payload

RLP RLP ...

... MUX MUX ...

CRC tail

IP IP UDP RTP SH Payload

Inte

rnet

Wire

less

Net

wor

k


Header Removal

• Reducing IP Overhead

...RLP

Payload

One Physical Layer Frame

Codec

RLP

MUX

Physical Layer

SH Payload

RLP RLP...

...MUX MUX ...

CRC tail

InternetW

ireless Netw

ork

SH Payload SH Payload


IP Overhead Computation

• Assume one video slice per one physical layer frame• Average Data Rate = C kbps• Video Frame Rate = 10 fps• Phy. Frame Duration = 20 ms• Number of slots / sec = 1/ 20 ms = 50• IP Overhead per slice = 44 bytes (RTP+UDP+IP+PPP)

– Bandwidth expansion due to PPP is ignored• IP Overhead data rate = 44 * 50 bytes/sec = 17.6 kbps• IP Overhead = 17.6 / C


Header Removal Savings

IP Overhead

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

20 24 28 32 36 40 44 48 52 56 60 64 68 72 76 80 84 88 92 96

Available vitrate for video

RTP/

UDP/

IP/P

PP O

verh

ead


Header Removal

• Synchronous delivery of video at constant frame rate and no frame dropping– Play out information can be recreated– RTP/UDP/IP headers can be removed over the air interface,

similar to SO60• For PDCH, scheduler constraints can be relaxed to deliver n

frames in n/fs (e.g. 300 ms for n = 3 for 10 fps)• This is similar to multiple video frames in one RTP packet in

VBR case• Requires RTP termination at the PDSN


Header Compression

• Let S = [ r1 r2 … ri ]’ be the EBR rates for video codec payload only (with no IP overhead)

• Let x = {0, 1, 2, 3, 4} be maximum compressed header size– The value of x depends on Compression Scheme, whether UDP

checksum is enabled, etc. x=0 for header removal• EBR rates with header compression = S-x• EBR rates S and compression scheme need to be

negotiated between mobiles, PDSN and content servers• This can be done via SDP parameter exchange or new

Service Option definition


Standards Changes

• Match slice sizes to physical layer packet sizes– Can be specified as a new SO or exchanged in SDP– Compliant with MPEG-4 and ITU codecs

• Changes to PDSN– RTP termination at PDSN

– For header removal on FL and header generation on RL– Straight forward extension of Service Option 60 procedures for video slice

sizes• Changes to Base Station

– Straight forward extension of Service Option 60 procedures for video slice sizes

• QoS on Delay Constraints– Need an upper limit for delivery of video packets– Enables synchronous delivery of video and speech– Lip-sync is easier to accomplish


Summary of EBR Benefits

• It is better– 1 to 2 dB of gain in PSNR

• It is faster– Rate Control Buffer delay can be eliminated or combined with Scheduler

delay– 1240 ms reduced to 440 ms for DCCH+SCH with 200ms delivery window– 1240 ms to 540 ms for PDCH with 300ms delivery window

• Enables Header Removal– IP overhead is not required; 50% to 25% savings for 32 to 64 kbps video

• Support for Generic Header Compression• Recommendations

– Adopt for MCS and MSS

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