wireless ad hoc podcasting
DESCRIPTION
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. - PowerPoint PPT PresentationTRANSCRIPT
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Wireless Ad Hoc Podcasting
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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
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Wireless Ad Hoc Podcasting
• Podcasting used for media content• But inflexible• Based on Delay-Tolerant Network
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outline
• Podcasting in the Internet• Delay-tolerant network• Wireless Ad Hoc Podcasting• Solicitation Strategies• Evaluation and simulation• Conclusion and comment
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Podcasting• Podcasting: dissemination of streaming
contents over the Internet.• Playback off line.
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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
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Podcasting in the Internet
• Retrieves and processes data from the feed URI
• Automatically downloads new entries
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Podcasting in the Internet
• Atom Syndication Protocol• Based on XML
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outline
• Podcasting in the Internet• Delay-Tolerant Network• Wireless Ad Hoc Podcasting• Solicitation Strategies• Evaluation and simulation• Conclusion and comment
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Delay-Tolerant Network
• Loosely connected network for asynchronous communication
• Intermittent connectivity
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Delay-Tolerant Network
• Every node scans periodically the network neighborhood
• Nodes associate pair wise• IEEE 802.11, Bluetooth• Receiver-driven, No flooding
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outline
• Podcasting in the Internet• Delay-Tolerant Network• Wireless Ad Hoc Podcasting• Solicitation Strategies• Evaluation and simulation• Conclusion and comment
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Wireless Ad Hoc Podcasting
• Enhancement of podcasting
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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
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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
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Wireless Ad Hoc Podcasting
• Subscribed channel• Public channel
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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.
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Wireless Ad Hoc Podcasting
• False positive– Possible
• False negative– Impossible!
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Wireless Ad Hoc Podcasting
• Data Structure– Distinct identifiers– Meta data– Internal structure• Public cache or subscribed channel• Request list for solicitation decision• Download status
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Wireless Ad Hoc Podcasting
• Protocol design– Receiver-driven– State machine– First state– Second state– Unbeknownst to its user(public cache)
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outline
• Podcasting in the Internet• Delay-Tolerant Network• Wireless Ad Hoc Podcasting• Solicitation Strategies• Evaluation and simulation• Conclusion and comment
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Solicitation Strategies
• An open question : how to solicit to satisfy the future request.
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Solicitation Strategies
• Most solicited• Least solicited• Uniform• Inverse proportional• No caching
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Most solicited
• Increase the probability in a popular feed• history-based ranking• Request list of locality
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Least solicited
• Opposite goal against most solicted• May waste resources•
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Inverse proportional
• Mitigate the waste of unpopular cache• Inverse proportional to its popularity
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Uniform and no caching
• Feed channel are treated equally and requested randomly
• No caching is used for benchmark
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outline
• Podcasting in the Internet• Delay-Tolerant Network• Wireless Ad Hoc Podcasting• Solicitation Strategies• Evaluation and simulation• Conclusion and comment
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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
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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
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Performance metrics
• Freshness
• Overall and per channel average freshness• Max-min fairness
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Result
• 50 nodes and 7 different channels.• varying
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Result
• Uneven popularity for ,a larger value increases the probability that unpopular channels are solicited
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Result
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Result
• Varying Publishing rate
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Result
• Varying Publishing rate
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Result
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outline
• Podcasting in the Internet• Delay-tolerant network• Wireless Ad Hoc Podcasting• Solicitation Strategies• Evaluation and simulation• Conclusion and comment
![Page 39: Wireless Ad Hoc Podcasting](https://reader036.vdocument.in/reader036/viewer/2022062410/56816386550346895dd471f0/html5/thumbnails/39.jpg)
Conclusion and comments
• The best overall performance is uniform strategy.
• Security problem• Based on Bluetooth?• Useful in sparse district?