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Multimedia over Ad Hoc Networks

Multimedia over Ad Hoc Networks. B Tech Project Under the guidance of Dr Huzur Saran. Ashish Kapoor Pankaj Thakkar. Introduction. Ad Hoc Networks (AHN) Infrastructure-less wireless networks Each mobile node acts as a router

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Multimedia over Ad Hoc Networks

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  1. Multimedia over Ad Hoc Networks B Tech Project Under the guidance of Dr Huzur Saran Ashish Kapoor Pankaj Thakkar

  2. Introduction • Ad Hoc Networks (AHN) • Infrastructure-less wireless networks • Each mobile node acts as a router • Rapid deployment and dynamic reconfiguration • Multimedia • Requirements • Predictable and Reliable Services • Low Delay and Low Jitter

  3. Adhoc Networks • Characteristics • Wireless Medium • High Error Rates • Burst Errors • Highly Dynamic Topology • Frequent route breakage • Routing • Traditional routing inappropriate • Low state maintenance

  4. Achievements • Developed Video Over Adhoc Networks An architecture for providing Multimedia Services over AHN. Adaptive Application Adaptive Application Prioritized Forward Error Correction FEC Network Layer Multi Path Routing

  5. Video over Ad-hoc Networks VAN Framework

  6. Multipath Routing Source Destination

  7. Adhoc On Demand Distance Vector Routing • Route Discovery • Source Initiated • On Demand • Route Maintenance

  8. S Multi-path Routing D • Use two routes for communication • Advantages • Fault Tolerance • Low Delay and Jitter • Alternate route • Scheme • Extension of AODV: Adhoc On Demand Distance Vector Routing • Determine two vertex disjoint routes in the graph

  9. Multi-path Routing Algorithm • Route setup using pruned broadcast • Determine first route using AODV • Determine second route using extended AODV, if the two routes have a common vertex then modify both the routes to achieve two distinct vertex disjoint routes if possible. Route Cache of B & C B C D A B C Initially Routes: ABCD, ACBD Final Routes: ABD, ACD

  10. Delay v/s {Rate/Mobility} Delay v/s Rate Delay v/s Mobility

  11. Variance v/s {Rate/Mobility} Variance v/s Rate Variance v/s Mobility

  12. Goodput v/s {Rate/Mobility} Goodput v/s Rate Goodput v/s Mobility

  13. Prioritized Forward Error Correction Codes

  14. Transmission of MPEG 1 Video • Standard MPEG-1 encoding • Intra Picture Frames • Prediction Frames • Bi-Directional Frames • Transmission Problems in MPEG-1 • Meant for data storage • Highly unstable to losses • Does not provide scalability

  15. Prioritized Forward Error Correction • FEC based on Reed Solomon Codes. • m-degreed polynomial • P(x) = a0 + a1 * x + … + am-1 * xm-1 • Evaluate P(x) for n values of x • Redundancy: n / m • Different redundancy based on frame type. Group of Picture Header I B B P B P B I Blocks of size 40 words each Blocks of size 60 words each Evaluate each block as a polynomial at 100 different values

  16. PET Performance PET Priorities for different frames Four Different Scenarios • Bare MPEG stream over AODV • Bare MPEG stream over Multipath Protocol • PET encoded MPEG stream over AODV • PET encoded MPEG stream over Multipath Protocol

  17. Discussion • Future Directions • Extension of application to enable network monitoring and adapting • Extending the Priority Encoding Scheme for recent MPEG standards • Image Processing at the receiving end to reconstruct video frames

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