1 / 39

Wireless Ad Hoc Podcasting

Wireless Ad Hoc Podcasting. Ad hoc . ad hoc network typically refers to a system of network requiring little or no planning a decentralized type of wireless network The network is ad hoc because it does not rely on a preexisting infrastructure. Wireless Ad Hoc Podcasting.

jaser
Download Presentation

Wireless Ad Hoc Podcasting

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Wireless Ad Hoc Podcasting

  2. Ad hoc • ad hoc network typically refers to a system of network requiring little or no planning • a decentralized type of wireless network • The network is ad hoc because it does not rely on a preexisting infrastructure

  3. Wireless Ad Hoc Podcasting • Podcasting used for media content • But inflexible • Based on Delay-Tolerant Network

  4. outline • Podcasting in the Internet • Delay-tolerant network • Wireless Ad Hoc Podcasting • Solicitation Strategies • Evaluation and simulation • Conclusion and comment

  5. Podcasting • Podcasting: dissemination of streaming contents over the Internet. • Playback off line.

  6. Podcasting in the Internet • Fairly simple • Channel to define a feed and make it accessible on a web server • Feed is an XML file, which contains a list of entries. • Subscribe to podcast channel by entering feed URI into Podcatcher

  7. Podcasting in the Internet • Retrieves and processes data from the feed URI • Automatically downloads new entries

  8. Podcasting in the Internet • Atom Syndication Protocol • Based on XML

  9. outline • Podcasting in the Internet • Delay-Tolerant Network • Wireless Ad Hoc Podcasting • Solicitation Strategies • Evaluation and simulation • Conclusion and comment

  10. Delay-Tolerant Network • Loosely connected network for asynchronous communication • Intermittent connectivity

  11. Delay-Tolerant Network • Every node scans periodically the network neighborhood • Nodes associate pair wise • IEEE 802.11, Bluetooth • Receiver-driven, No flooding

  12. outline • Podcasting in the Internet • Delay-Tolerant Network • Wireless Ad Hoc Podcasting • Solicitation Strategies • Evaluation and simulation • Conclusion and comment

  13. Wireless Ad Hoc Podcasting • Enhancement of podcasting

  14. Wireless Ad Hoc Podcasting • No means to search for podcast channels • Feed channel should be known priori • Enhancement: discovery channel • List of the feed channel, which may be empty

  15. Wireless Ad Hoc Podcasting • Entries must update constantly to reflect the latest status • Entries will reach a node in arbitrary order • Atomic unit • Feed channel is composed of a mixture of entries of music, news items, weather updates ,etc

  16. Wireless Ad Hoc Podcasting • Subscribed channel • Public channel

  17. Wireless Ad Hoc Podcasting • Request for contents: • Any content • Feed channel • Entry • Feed channel + entry • Time • Uniqueness : matches any entry not in a provided list of entry ID’s.

  18. Wireless Ad Hoc Podcasting • False positive • Possible • False negative • Impossible!

  19. Wireless Ad Hoc Podcasting • Data Structure • Distinct identifiers • Meta data • Internal structure • Public cache or subscribed channel • Request list for solicitation decision • Download status

  20. Wireless Ad Hoc Podcasting • Protocol design • Receiver-driven • State machine • First state • Second state • Unbeknownst to its user (public cache)

  21. outline • Podcasting in the Internet • Delay-Tolerant Network • Wireless Ad Hoc Podcasting • Solicitation Strategies • Evaluation and simulation • Conclusion and comment

  22. Solicitation Strategies • An open question : how to solicit to satisfy the future request.

  23. Solicitation Strategies • Most solicited • Least solicited • Uniform • Inverse proportional • No caching

  24. Most solicited • Increase the probability in a popular feed • history-based ranking • Request list of locality

  25. Least solicited • Opposite goal against most solicted • May waste resources

  26. Inverse proportional • Mitigate the waste of unpopular cache • Inverse proportional to its popularity

  27. Uniform and no caching • Feed channel are treated equally and requested randomly • No caching is used for benchmark

  28. outline • Podcasting in the Internet • Delay-Tolerant Network • Wireless Ad Hoc Podcasting • Solicitation Strategies • Evaluation and simulation • Conclusion and comment

  29. Network and simulation model • Two nodes can communicate with if distance is smaller than a threshold value • No collision and interference • Random waypoint mobility model

  30. Scenario Setting • Scenario • Radio range 10 m • Moving speed 1 m/s • Rate of radio devices 1 Mb/s • Entry size 250 KB • Square 300 m X 300 m • Popularity

  31. Performance metrics • Freshness • Overall and per channel average freshness • Max-min fairness

  32. Result • 50 nodes and 7 different channels. • varying

  33. Result • Uneven popularity for ,a larger value increases the probability that unpopular channels are solicited

  34. Result

  35. Result • Varying Publishing rate

  36. Result • Varying Publishing rate

  37. Result

  38. outline • Podcasting in the Internet • Delay-tolerant network • Wireless Ad Hoc Podcasting • Solicitation Strategies • Evaluation and simulation • Conclusion and comment

  39. Conclusion and comments • The best overall performance is uniform strategy. • Security problem • Based on Bluetooth? • Useful in sparse district?

More Related