Multimedia Streaming Multimedia Streaming Gateway With Jitter DetectionGateway With Jitter Detection

Siu-Ping Chan, Chi-Wah KokSiu-Ping Chan, Chi-Wah Kok

Albert K. WongAlbert K. WongIEEE TRANSACTIONS ON MULTIMEDIA, June 2005IEEE TRANSACTIONS ON MULTIMEDIA, June 2005

OutlineOutline

• Introduction

• Related Work

• Jitter-Aware QoS for multimedia traffic– Jitter Detection Scheme 1– Jitter Detection Scheme 2

• Simulation Results

• Conclusion

IntroductionIntroduction

• When a multimedia stream is transported over packet-switched network, it assumes a constant network delay.

• Investigate a novel active buffer management scheme, “Jitter Detection” (JD) based on gateway-based

• Discard packet with enough jitter which is useless to clients

Related WorkRelated Work

• Gateway-based packet-switch network congestion control

• RED-drop packets randomly with a probability according to current queue length and a queue-size

• Like RED, but with average delay

Preparation in JD schemePreparation in JD scheme

• Classify a packet as TCP or multimedia streaming packet with protocol field in IPv4

• Delay jitter counter with four quantized regions stored in TOS field in IPv4

• More near client, less discard– Need residual distance– With TTL field as residual distance– Servers and clients need to exchange hop-count

information during session setup and routing update

Jitter-Aware QoS for multimedia trafficJitter-Aware QoS for multimedia traffic

• The packet size of the streaming is assumed to be fixed (ex. MPEG-2 VBR audio traffic)

• Losing some packets will still allow partial decoding of multimedia data

Jitter Detection Scheme 1Jitter Detection Scheme 1

Jitter Detection Scheme 1Jitter Detection Scheme 1

• Estimate delay– CBO: current buffer occupancy of the output q

ueue– LC: output link capacity– delay = CBO* Packet_Size/LC

• Count average delay– ave_delay= ave_delay*(1-wd)+delay*wd

• Count jitter– Jitter = delay- ave_delay

Jitter Detection Scheme 1Jitter Detection Scheme 1

• Count threshold (accumulated jitter)

• Decide if dropping or not

-

current

past accumulate

Jitter Detection Scheme 2Jitter Detection Scheme 2

• What differ with JD1– Jitter tolerance must be bigger if packet near

destination (ie, fixed_th bigger when near clients)

– Actual residual distance is hard to obtain• With TTL as residual distance

Performance Bounds and Analysis Performance Bounds and Analysis of Dropping Decisionof Dropping Decision

• Analysis the upper bound on the probability of dropping packet with Chebyshev inequality

• : delay value of received multimedia packet

• : sample mean delay

• : standard deviation

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Simulation ResultsSimulation Results

• With Network Simulator

• Two TCP source & two UPD source (Multimedia traffic)

• RED & JD are implemented in the gateways for congestion control of the TCP and UDP packets

• Two sets of additional simulations are performed using DropTail and the RED congestion control schemes

Simulation ResultsSimulation Results

Simulation Results-TCP FriendlinessSimulation Results-TCP Friendliness

• Greedy high-bandwidth UDP traffic will typically lower the throughput of TCP flows

• With TCP and UDP apply different buffer management schemes before putting into FIFO queue– JD have certain TCP-friendliness such that it

will not lower the throughput of the TCP flows

Simulation Results-TCP FriendlinessSimulation Results-TCP Friendliness

RED for TCPdecrease !!

Simulation Results-TCP FriendlinessSimulation Results-TCP Friendliness

lower drop rate

Simulation ResultsSimulation ResultsDelay Jitter of Multimedia TrafficDelay Jitter of Multimedia Traffic

Delay jitter for some received UDP packets using RED

Simulation ResultsSimulation ResultsDelay Jitter of Multimedia TrafficDelay Jitter of Multimedia Traffic

average delay jitter for some received UDP packets using different queue management scheme

periodic because of TCP-congestion

Simulation ResultsSimulation ResultsDelay Jitter of Multimedia TrafficDelay Jitter of Multimedia Traffic

add two UDP streams

Simulation Results Simulation Results Useful Goodput of Multimedia TrafficUseful Goodput of Multimedia Traffic

• Useful : packet arrives at the client within one half of the playout interval

Useful threshold=0.1spacket size= 900 bytes

Simulation Results Simulation Results Useful Goodput of Multimedia TrafficUseful Goodput of Multimedia Traffic

low

packet size , usefulless goodput , variation

Simulation Results Simulation Results Audio Quality ComparisonAudio Quality Comparison

Although JD1 throughput lower, but SNR higher

ConclusionConclusion

• A novel streaming friendly gateway-based buffer management scheme- JD is proposed

• JD improve QoS of multimedia networks by detecting and discarding multimedia packets with higher jitter

• Also improve JD scheme with residual hop-count

Chebyshev inequalityChebyshev inequality

• Given only mean and variance, count an upper bound on the probability that some random variable is >= a set value

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