250 likes | 383 Views
Multimedia Streaming Gateway With Jitter Detection. Siu-Ping Chan, Chi-Wah Kok Albert K. Wong IEEE TRANSACTIONS ON MULTIMEDIA, June 2005. Outline. Introduction Related Work Jitter-Aware QoS for multimedia traffic Jitter Detection Scheme 1 Jitter Detection Scheme 2 Simulation Results
E N D
Multimedia Streaming Gateway With Jitter Detection Siu-Ping Chan, Chi-Wah Kok Albert K. Wong IEEE TRANSACTIONS ON MULTIMEDIA, June 2005
Outline • Introduction • Related Work • Jitter-Aware QoS for multimedia traffic • Jitter Detection Scheme 1 • Jitter Detection Scheme 2 • Simulation Results • Conclusion
Introduction • 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 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 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 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 1 • Estimate delay • CBO: current buffer occupancy of the output queue • 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 1 • Count threshold (accumulated jitter) • Decide if dropping or not - past accumulate current
Jitter 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 of 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
Simulation 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 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 Friendliness RED for TCP decrease !!
Simulation Results-TCP Friendliness lower drop rate
Simulation ResultsDelay Jitter of Multimedia Traffic Delay jitter for some received UDP packets using RED
Simulation ResultsDelay Jitter of Multimedia Traffic periodic because of TCP-congestion average delay jitter for some received UDP packets using different queue management scheme
Simulation ResultsDelay Jitter of Multimedia Traffic add two UDP streams
Simulation Results Useful Goodput of Multimedia Traffic • Useful : packet arrives at the client within one half of the playout interval Useful threshold=0.1s packet size= 900 bytes
Simulation Results Useful Goodput of Multimedia Traffic low packet size , usefulless goodput , variation
Simulation Results Audio Quality Comparison Although JD1 throughput lower, but SNR higher
Conclusion • 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 inequality • Given only mean and variance, count an upper bound on the probability that some random variable is >= a set value