Rate-Based Active Queue Management with Priority Classes for Better Video Transmission

Rate-Based Active Queue Management with Priority Classesfor Better Video Transmission

Jae Chung and Mark Claypool

Computer Science DepartmentWorcester Polytechnic InstituteWorcester, Massachusetts, USAhttp://perform.wpi.edu/

ISCC02 WPI Rb-RIO #2

Streaming Media Applications

Can use TCP– Hides network information– Difficult to use media scaling upon– Hard to control transmission timing– Higher jitter due to traffic burst

Often use UDP– Control the flow as desired

• Responsiveness, Fairness– Can tolerate some frame losses

• Trickier for Video Streaming


Difficulty of Video Streaming

Inter-frame dependencies (Compression) Large frames: fragmented in IP layer

I B PB BB I

A Sample MPEG Stream

I B PB BB


Outline

Introduction Approaches Rb-RIO Experiments Results Summary


Approaches to The Problem

Application Support– Redundancy and Error Correction– Media Scaling

Network Architectural Support– Integrated Services (IntServ)– Differentiated Services (DiffServ)

Router Support– Resource Reservation (WFQ, …)– Priority Class-Based Queue Management


Basic Idea: Avoid Domino Frame Loss Using Priority Queuing

Queue supports 3 priority class– Drop all the lowest class packets before starting

to drop the next class packets MPEG Video Frame Mapping

– Map I-, P- and B-frame packets to High, Mid and Low priority classes

TCP Mapping– Randomly map TCP packets to the 3 classes

(standalone better-than-best-effort Queue)


AQM Support for Priority-Classes

… RED RIO

Average Queue Size Based

… Rb-RED Rb-RIO

Rate Based

- Detect Congestion- Determine Degree- Notify SourcesActive Queue Management


Rb-RED

Components– Limit: Queue Limit– Q: Queue Size– EAR: Estimated Arrival Rate – SR: Service Rate

Drop Logic (for incoming packets)if (Q > Limit)

Dropelse if (EAR > SR)

Drop with P = (EAR – SR) / EAR

SREAR


Rb-RIO

Drop Logicif (Q > Limit)

Dropelse if (EARhigh > SR)

if (L-class or M-class) Dropif (H-class) Drop with P = (EARhigh– SR) / EARhigh

else if (EARhigh+ EARmid > SR)if (L-class) Dropif (M-class) Drop with P = (EARhigh+ EARmid– SR) / EARmid

else if (EAR > SR)if (L-class) Drop with P = (EAR – SR) / EARlow

SR

EAR

EARlow

EARmid

EARhigh SR

EAR

EARlow

EARmid

EARhigh

EAR EARlow

EARmid EARhigh

SR


Rb-RIO Mappings

MPEG Video– I-frame packets = H-class– P-frame packets = M-class– B-frame packets = L-class

TCP– Randomly map incoming TCP packets– H-class : M-class : L-class = x : y : z


Outline

Introduction Approaches Rb-RIO Experiments Results Summary


Experiments

Implement Rb-RIO in NS General Settings

– Network Packet Size = 1 KB– MPEG Frame Size (from a news clip)

I, P, B = 11, 8, 2 (KB)– Rb-RIO Priority Class Mapping for TCP

H : M : L = 7 : 3 : 0 Compare Rb-RIO with RED, Drop-Tail

– Using TCP, MPEG and MIX (TCP + MPEG)


n1-n2: q_size = 100qweight = 0.0003

RED: max_th = 60min_th = 20max_p = 0.1

Rb-RIO: interval = 1msear_k = 0.5aggr_p = 2.5

0 10 20 30

40 Flows

20 Flows

Simulation Time (Seconds)

s59

s60

s1

s2

n1

r59

r60

r1

r2

n225Mbps, 20ms

25Mbps, 5ms 25Mbps, 5ms

packet_size = 1kbFTP-TCP

FTP-TCP

EXP TCP: Setup


EXP TCP: Summary

Comparing Rb-RIO with Drop-Tail and RED (well-configured)– Throughput: All compatible– Drop Rate: All compatible– Fairness: RED and Rb-RIO are

compatible and fairer than Drop-Tail


EXP MPEG: Setup




0 10 20 30

40 Flows

20 Flows


s59

s60

s1

s2

n1

r59

r60

r1

r2

n225Mbps, 20ms


packet_size = 1kb

ResponsiveMPEG

UnresponsiveMPEG


EXP MPEG: Pkt & Frm Statistics

Throughput Pkt Loss % Frm Loss %

Deco Loss %

Drop-Tail 19.82 Mbps 13.1 22.8 43.2

RED 18.65 Mbps 9.0 29.4 53.7

Rb-RIO 20.81 Mbps 11.2 36.9 39.8

Responsive MPEG

Unresponsive MPEGThroughput Pkt Loss % Frm Los

s %Deco Loss %

Drop-Tail 14.27 Mbps 23.4 38.7 87.0

RED 15.18 Mbps 20.6 43.5 92.1

Rb-RIO 9.70 Mbps 34.5 88.8 88.8


EXP MPEG: Decodable Frames (Responsive MPEG)


EXP MPEG: Decodable Frames (Unresponsive MPEG)


EXP MPEG: Fairness

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0- 10 Sec 10- 20 Sec 20- 30 Sec

Jain'

s Fa

irnes

s Ind

ex

Drop- TailREDRb- RIO


EXP MPEG: Summary

Rb-RIO improves video transmission over Drop-Tail and RED– Effective use of network bandwidth– Smoother video streams (less jitter)

Improves fairness among video streams– Same kind of streams– Different kind of streams


EXP MIX: Setup




0 10 20 30

20 Flows

20 Flows


s59

s60

s1

s2

n1

r59

r60

r1

r2

n225Mbps, 20ms


packet_size = 1kb

ResponsiveMPEG

UnresponsiveMPEG

20 FlowsFTP-TCP


EXP MIX: Fairness

0

2

4

6

8

10

12

14

16

18

20

Drop-Tail

RED Rb-RIO

Drop-Tail

RED Rb-RIO

Drop-Tail

RED Rb-RIO

0- 10 Seconds 10- 20 Seconds 20- 30 Seconds

Aggr

egat

ed T

hrou

ghpu

t (M

bps)

TCPResp MPEGUnresp MPEG


EXP MIX: Summary

Rb-RIO improves video transmission over Drop-Tail and RED as in EXP MPEG

Protects TCP from other flows that are unresponsive or response differently to network congestion


Summary

Rb-RIO behaves compatibly with well-configured RED on TCP flows

Offers efficient and smoother video transmission

Improves fairness among video streams

Protects TCP using configurable TCP mapping ratio


Future Work

Thorough evaluation of Rate-Based AQM mechanism (with TCP)

Try and evaluate Rb-RIO with other video streams (H.263+, RealVideo)

Design an AQM mechanism that can control delay for interactive multimedia streaming

Rate-Based Active Queue Management with Priority Classes for Better Video Transmission

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