1 MPEG Streaming over Mobile Internet Kyunghee Lee and Myungchul Kim {leekhe, mckim}@icu.ac.kr

1

MPEG Streaming over Mobile Internet

Kyunghee Lee and Myungchul Kim

{leekhe, mckim}@icu.ac.kr

2

Contents• Introduction

• Related Work

• Proposed Mechanism

• System Design

• Testbed Configuration

• Experiments

• Performance Evaluation

• Conclusions

• References

3

Introduction• General multimedia data characteristics

– Intolerant to delay and jitter variance

– Error-sensitive

• Characteristics of mobile Internet– Frequent routing path changes due to handoffs

– Higher error rate in wireless link

• Effects on streaming multimedia data in mobile Internet– Handoff delay

– Re-routing toward congested network delay increment

– Higher packet loss probability due to mobility

Significant quality degradation of streaming multimedia data

4

Introduction (cont’d)

• Popular Quality of Service (QoS) guarantee mechanisms

– Differentiated Service (DiffServ) [2]• Guarantees aggregated QoS for multiple flows• Can not guarantee specific QoS requirement for each data flow

– Integrated Service (IntServ)• Network resource reservation for specific data flow• Strict guarantees for multimedia streams with various QoS

requirements• Resource Reservation Protocol (RSVP) [3]

5

Introduction (cont’d)

• Problems of RSVP in Mobile Internet– Mobile Host (MH) handoff invalidates existing reservation paths

overhead and delay to re-establish new RSVP session

– Movement to congested wireless cell fail to get admission to re-establish new RSVP session

Seamless QoS guarantees are impossible

• Existing approaches– Mobile RSVP (MRSVP) [15]

– Hierarchical Mobile RSVP (HMRSVP) [16]

– A method of Concatenation and Optimization of Reservation Path (CORP) [10]

6

Related Work• Priority-based scheduling for MPEG streaming on

Mobile Internet– Differentiated delivery service depending on the

importance of each MPEG frame data

R1

FA

CH

I

B

B

P

I

BP B

I

P

Priority-awarePriority-awareMPEG ServerMPEG Server

MHMH

: : MPEG video streamMPEG video stream

: : Non-multimedia TrafficNon-multimedia Traffic

Packet dropPacket drop

MPEG ClientMPEG Client

congestedcongested

7

Related Work (cont’d)

• Classify IP packets into two classes depending on its payload– Class 1: containing MPEG and GOP header (priority 1)

– Class 2: containing MPEG I frame (priority 1)

– Class 3: containing MPEG B, P frame (priority 7, best-effort)

• Uses TOS field in IP packet header as a classifier

….

4-4-bitbitversionversion

4-4-bitbitheader len.header len.

8-bit TOS field 16-16-bit total length (in bytes)bit total length (in bytes)

16-16-bit identificationbit identification 3-3-bit flagbit flag 13-13-bit fragment offsetbit fragment offset

8-8-bit time-to-live (TTL)bit time-to-live (TTL) 8-8-bit protocolbit protocol 16-16-bit header checksumbit header checksum

32-32-bit source IP addressbit source IP address

00 1616 3131

3-bit precedence field(currently ignored)

minimizedelay

maximizethroughput

maximizereliability

minimizemonetary

cost

1-bitunused

4 TOS bits

8


• Priority-aware MPEG streaming server

MPEGvideo file

Analysis Packetization

Priority setting

MPEGvideo client

UDP

Priority-aware MPEG video stream server

Parse theMPEG file

make an offsettable

move MPEG datafrom a file to the buffer

check up the data inthe buffer set the TOS

value of thepacket

decide the value ofTOS field

9


• Mobile IP Foreign Agent (FA)– Is the most probable spot of packet loss due to the network

congestion– Acts as a gateway router for its own wireless subnet– Runs mobile IP FA daemon program– Performs priority-based CBQ scheduling for the traffic delivered

toward MH

• Mobile MPEG client– Plays MPEG video stream from the server

• Advantages

– Simple and light-weight mechanism suitable for wireless/mobile

networking environment

– Significant video quality improvement can be achieved though the

extra bandwidth is scarcely consumed

10


• Testbed configuration

Non-diffserv routerNon-diffserv routerR

HA FA

MH

BackgroundBackgroundtraffictraffic

Priority-awarePriority-awareMPEG serverMPEG server

MPEG video streamMPEG video stream

Priority-based scheduling on/offPriority-based scheduling on/off

WirelessWirelesssubnet 1subnet 1

WirelessWirelesssubnet 2subnet 2

Experiment scenarioSample MPEG file specification

Background traffic pattern

File size 1.2 Mbytes

Playing outDuration 48 sec

Frame rate 30 fps

Avg. bit rate

214 Kbps

ContainingFrames

102 I, 404 P, 1010 B

* * Total Total 1516 frames 1516 frames

****The bandwidth limit in the WaveLAN II The bandwidth limit in the WaveLAN II wireless link: wireless link: 5.07 Mbps5.07 Mbps

11


• Experimental results– Number of the received packets (at client) containing either

MPEG header or I-frame (Class 1, 2)• Each packet size: 1024 bytes• Total number of Class 1 or 2 packets: 151• Number of the received packets: 151 (the proposed mechanism), 121

(FIFO scheduling)

– Transfer rate variation of the MPEG video stream

• Transfer rate is more independent on the amount of the background traffic

( ) Class 1, 2 packets are served by the priority-based scheduling

80000

100000

120000

140000

160000

180000

200000

1 5 9 13 17 21 25 29 33 37 41 45 (sec)

(bp

s)

FIFO scheduling priority-based CBQ scheduling

12


• Experimental results (cont’d)– PSNR value distribution

• Amount of the received traffic: 824 Kbytes (FIFO), 852 Kbytes (CBQ) out of total 1.2 Mbytes

• Number of frames 20 dB: 919 (FIFO), 775 (CBQ)• Number of frames with 78 dB: 151 (FIFO), 192 (CBQ)• 78 dB: same quality with the original image 20 dB: impossible to be recognized by human eyes

0

50

100

150

200

250

300

350

400

450

10 20 30 40 50 60 70 78

PSNR (dB)

Num

ber

of fr

am

es

FIFO scheduling Priority-based CBQ scheduling

Out of total1440

13


• CORP– Base Station (BS) takes charge of making and managing

RSVP sessions on behalf of MH– Consists of two main processes

• Concatenation of Reservation Path (CRP) process– Reservation path extension technique– Current BS pre-establishes pseudo reservation path (PRP) toward its

neighboring BSs to prepare for MH’s handoff – When MH handoffs, corresponding PRP is activated to guarantee QoS

for MH

• Optimization for Reservation Path (ORP) process– Solves infinitely long path extension problem and reservation

path loop problem of CRP process– Optimizes the extended reservation path

14


• CRP Process

BS_CBS_BBS_A

I. MH requests a new RSVP session and BS_B makes it on behalf of the MH

II. BS_B sends CRP inform messages to its neighbors

CRP inform

CRP inform

CORP message

RSVP session

PRP

Activated PRP

15


• CRP Process

BS_CBS_BBS_A



III. BS_B makes PRP to its neighbors

CORP message

RSVP session

PRP

Activated PRP

16


• CRP Process

BS_CBS_BBS_A




IV. MH handoffs toward BS_C’s cell

CORP message

RSVP session

PRP

Activated PRP

17


• CRP Process

BS_CBS_BBS_A




IV. MH handoffs toward BS_C’s cellCRPactivate

V. BS_C sends CRP activate message to the previous BS (BS_B)

CORP message

RSVP session

PRP

Activated PRP

18


CRP Process

BS_CBS_BBS_A






VI. BS_B forwards MPEG-1 video through the activated PRP

CORP message

RSVP session

PRP

Activated PRP

19


CRP Process

BS_CBS_BBS_A






VI. BS_B forwards MPEG-1 video through the activated PRP

VII. BS_B terminates useless PRP toward BS_A

CORP message

RSVP session

PRP

Activated PRP

20


• ORP Process

BS_CBS_BBS_A

CORP message

RSVP session

PRP

Activated PRP

I. BS_C sends IGMP group report message to its gateway router

IGMPreport

21


ORP Process

BS_CBS_BBS_A

CORP message

RSVP session

PRP

Activated PRP


II. BS_C joins into the existing multicast RSVP session

CRPrelease

III. BS_C sends CRP release message to the previous BS (BS_B)

22


ORP Process

BS_CBS_BBS_A

CORP message

RSVP session

PRP

Activated PRP




IV. BS_B terminates the activated PRP and BS_C uses the newly optimized one to deliver MPEG data stream to MH

23


ORP Process

BS_CBS_BBS_A

CORP message

RSVP session

PRP

Activated PRP




IV. BS_B terminates the activated PRP and BS_C uses the newly optimized one to deliver MPEG data stream to MH

V. BS_B leaves the multicast RSVP session

CRPinform

CRPinform

VI. BS_C sends CRP inform messages to its neighbors to prepare MH’s probable movement

24

Proposed Mechanism

• Motivation– To provide QoS guarantees for MPEG video streaming services

with mobility support

• Proposed System– Uses CORP to guarantee seamless QoS in mobile networks

– Provides MPEG-1 video streaming services over CORP

– CORP-aware video streaming server and client

– CORP-capable mobile agents (Base Stations)

25

System Design

• Video Server Architecture– CORP adaptation module

handles CORP messages and takes charge of resource reservation process

– MPEG-1 traffic transfer module transfers MPEG-1 stream to BS at the speed of a reserved bandwidth

Video Server

RSVP

TCP/UDP

IP

Wired Link

CORP AdaptationModule

MPEG-1 TrafficTransfer Module

CORP message

MPEG-1 data

26

System Design (cont’d)

• Base Station Architecture– CORP message handler

module handles CORP messages which are generated by neighboring BSs or a mobile client

– traffic forward module receives MPEG-1 streaming data from the video server and forwards it to a neighboring BS or directly delivers it to the client

CORP

RSVP

TCP/UDP

IP/Mobile IP

Wired/Wireless Link

CORP MessageHandler Module

TrafficForward Module

27


• Client Architecture– CORP adaptation module

handles CORP messages– Handoff detection module

detects a handoff and determines when MH has to request the activation of PRP

– MPEG-1 traffic receiver module receives MPEG-1 streaming data from a current BS

– MPEG-1 video playback module plays the MPEG-1 video from the received stream

Client

TCP/UDP

Mobile IP

Wireless Link

CORP AdaptationModule

MPEG-1 TrafficReceiver Module

Handoff DetectionModule

MPEG-1 VideoPlayback Module

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• MPEG-1 Service Procedure over CORP before Handoff

Video Server BS1 ClientBS2

Service Request

Service Request Ack

Service Request

Service Request Ack

RSVP path

RSVP resv

MPEG-1 trafficMPEG-1 traffic

PRP establishment

ClientHandoffs

(BS1BS2)

29


• MPEG-1 Service Procedure over CORP after Handoff

Video Server BS1 ClientBS2Client

handoffs

CRP Activate RequestCRP Activate

CRP Activate Ack

MPEG-1 traffic MPEG-1 traffic MPEG-1 traffic

ORP Request

ORP Request Ack

RSVP path

RSVP resv

MPEG-1 trafficMPEG-1 traffic

(BS1BS2)

30

Testbed Configuration• Network Architecture

Wired subnet bandwidth10 Mbps Ethernet

Wireless subnet bandwidthIEEE 802.11b wireless LAN with the bandwidth of 11 Mbps

BSRuns FA daemon of Mobile IP

Runs CORP daemon

ClientRuns MH daemon of Mobile IP

Runs VOD client program

Video ServerSupports CORP-aware MPEG-1 streaming service

MH

BS2

Gateway

BS1

Video Server

Wireless Subnet_1

Wireless Subnet_2

Wired Subnet_1 Wired Subnet_2

Home Agent

31

Experiments• Experiment Scenarios

– Background traffic generation: MGEN– Maximum throughput of wired network:

9.34 Mbps– Wired subnet_1: non-congested– Wired subnet_2: congested

• 8.2 Mbps background traffic– Movement of MH: BS1 BS2

• Experiment CasesI. MPEG-1 streaming with CORP and TCPII. MPEG-1 streaming with TCP onlyIII. MPEG-1 streaming with CORP and UDPIV. MPEG-1 streaming with UDP only

Shrek

Resolution 352 X 288

Average Data Rate (Mbps)

1.39

Frame Rate (fps) 25

Play out duration (sec)

80

Total number of frames

2,000

Sample Video Clip Specification

32

Performance Evaluation• QoS Guarantee

– Data rate is measured at client per each second while the sample MPEG file is being delivered

– Not much difference in data rate distribution between before and after handoff cases in (I)

– Amount of packet loss due to handoff is about 81Kbytes in (I)– 84 percents are less than 0.3 Mbps after handoff in(II)

I. MPEG-1 Streaming with CORP and TCP II. MPEG-1 Streaming with TCP only

0

10

20

30

40

50

60

70

80

0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7 3

Data receiving rate per each second (Mbps)

Pe

rce

nta

ge

(%

)

Before HandoffAfter Handoff

0

10

20

30

40

50

60

0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7 3


Per

cent

age

(%)

Before Handoff

After Handoff

* 150KBps bandwidth reserved

33

Performance Evaluation (cont’d)

• QoS Guarantee (cont’d)

– Not much difference in data rate distribution between before and after handoff cases in (I)

– Average data rate before handoff is significantly higher than that after handoff in (II)

– Average packet loss rate is about 0.6 Mbps in (II)

0

10

20

30

40

50

60

70

80

90

100

1 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2


Pe

rce

nta

ge

(%

)


0

10

20

30

40

50

60

70

80

90

100

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2


Pe

rce

nta

ge

(%

)


I. MPEG-1 Streaming with CORP and UDP II. MPEG-1 Streaming with UDP only

* 200KBps bandwidth reserved

34


• Quality of Streaming Video

– If Peak Signal to Noise Ratio (PSNR) is less than 20 dB, the frame can be regarded as being lost

– In (I), MPEG-1 streaming data did not suffer from loss or delay under the congested situation

– 11 frames were lost during CRP process time in (I)– the total number of received frames is only 1107 frames out of 2000

frames for 80 seconds in (II)

0

10

20

30

40

50

60

70

80

90

0 200 400 600 800 1000 1200 1400 1600 1800 2000

Frame number

PS

NR

(dB

)

Handoff0

10

20

30

40

50

60

70

80

90

0 200 400 600 800 1000 1200 1400 1600 1800 2000

Frame number

PS

NR

(dB

)

Handoff

I. MPEG-1 Streaming with CORP and TCP II. MPEG-1 Streaming with TCP only

35


• Quality of Streaming Video (cont’d)

– The average PSNR is 69.6 dB before MH’s handoff and 68.6 dB after MH’s handoff in (I)

– MH could not play back MPEG-1 video stream correctly after handoff in (II) because of too high packet loss rate (0.6 Mbps)

0

10

20

30

40

50

60

70

80

90

0 200 400 600 800 1000 1200 1400 1600 1800 2000

Frame number

PS

NR

(dB

)

Handoff0

10

20

30

40

50

60

70

80

90

0 200 400 600 800 1000 1200 1400 1600 1800 2000

Frame number

PS

NR

(dB

)

Handoff

I. MPEG-1 Streaming with CORP and UDP II. MPEG-1 Streaming with UDP only

36

Conclusions• QoS guarantee for MPEG-1 streaming service in Mobile

Internet– QoS guarantee mechanism with mobility support – CORP– Implementation of MPEG-1 streaming service over CORP

• Streaming Video Quality Improvement– Significantly better PSNR values in both cases of using TCP and UDP

when CORP mechanism is applied– MPEG-1 streaming with CORP and TCP provided the highest video

quality in the experiments

• Future work– Reduction in the packet loss during a handoff with CORP– Reduction in the packet loss over wireless links when UDP is used as

a transport protocol

Documents

1 MPEG Streaming over Mobile Internet Kyunghee Lee and Myungchul Kim {leekhe, mckim}@icu.ac.kr