Presented by Santhi Priya EdaVinutha 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 802.16 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 802.16 – 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.

THANK YOU