Presented by Santhi Priya Eda Vinutha Rumale

 Introduction  Approaches  Video Streaming Traffic Model  QOS in WiMAX  Video Traffic Classification over WiMAX  Simulation Results  Conclusion

 Problem : Transmitting MPEG video streams over WiMAX networks “Effectively”  Solution: Cross layer content aware traffic classification  How ?

 Problems Bandwidth Resources  Factors Stringent QOS Efficient Resource Management Scalability

 Worldwide Interoperability for Microwave Access.  Alternative for cable and DSL  Broadcasting  Based on IEEE standard.  Each traffic flow is mapped with appropriate service class.

 Rate Adaptive Method  Adaptive Scalable Video Coding  Active frame dropping  Frame Discarding Solution based on packet life time  Priority based frame dropping algorithm

 Feedback based video rate control  Optimum video coding rate Drawbacks  Channel Variations  Computational Complexity  Heterogeneity

Scalable Video Coding  One base layer and multiple enhancement layers. Active Frame Dropping  Drops Frames.  Application delay limit.  Solution based on packet life-time. Priority Based Frame Dropping  Temporary bandwidth reduction.  Frame type.

 Cross-layer design.  MPEG traffic.  No Complexity at video servers.  No feedback.

 Complex!!  Video Compression Standards MPEG-2,MPEG-4  MPEG-4 GOP-Group of Pictures Types of Frames I-Frames P-Frames B-frames

I Frames  Variable Bit Rates(VBR) Two Scales The Small Variation within a scene period. Large variation among different scenes.  Size of the nth I frame located at the kth scene,XI(n)is given by

Where - Mean activity of scene k and represents large variations. -Log normally distributed random variable. - Small variations -Normal random variable

P and B Frames  Independent Random Variable.  Log-Normal Distributions with parameters and

 GOP = 2 per second.  I-frames – 2 per second.  P-frames – 8 per second.  B-frames – 20 per second.  The average bit-rate for each of the frames is as follows. = 273 Kbps = 588 Kbps = 1094 Kbps = 1955 Kbps

 WiMAX supports Connectivity for broadband communications. Wireless access to mobile users.  rtPS – Real-time polling sevice IEEE – QoS Classes Minimum reserved traffic rate Maximum sustained traffic rate

 Avg Bitrate – 2Mbps  Avg size of frame – 6.8Kb to 17Kb  Video frame fragments into IP packets and MDU (MAC-layer data units)  Poor physical layer leads to loss of MDUs  Solution - Multilevel service classification

 Cross layer, content aware traffic classification method  Three types of Flows – based on different frames  IP header – ToS ( Type of Service )  Call admission control process

 Protect valuable frames i.e., I and P frames from loss.  Video stream is limited by downlink(DL) queue in the BS.  Small DL - Results in delay and drop of packets.  Large DL – low admittance, low utility, not scalable.  Optimum minimum reserved bit rate.

 I frame > Minimum reserved bit rate  P frame < Minimum reserved bit rate  B frame < Minimum reserved bit rate  P frames > B frames  Probability of dropping B frames > P frames > I frames

 OPNET Simulator.  One Base Station, 11 Subscriber Stations and video servers.  Single level, Minimum reserved bitrate = 884 Kbps  Multilevel, Minimum reserved bitrate for I frames = 384 Kbps P frames = 300 Kbps B frames = 200 Kbps  Minimum required bandwidth for each video stream is almost 2 Mbps.  6MB of BS’ memory space as buffer for each Subscriber station.

 Proposed solutions to increase the performance of MPEG video transmission.  Challenges of transmitting video streams over wireless networks.

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