CarTorrent ® : Cars get to have fun too Kevin C. Lee and Ian S. Yap TA: Uichin Lee Prof Mario Gerla

Introduction Vehicular Ad-hoc networks(VANETs) have these characteristics: Vehicular Ad-hoc networks(VANETs) have these characteristics: 1. Nodes have high computing power 2. Nodes highly mobile 3. Intermittent connectivity 4. Locally Dense networks 5. Cooperation between nodes not guaranteed An interesting application for VANETs is implementation of a peer-to-peer file-sharing system/protocol An interesting application for VANETs is implementation of a peer-to-peer file-sharing system/protocol Many names for it, in our project, its CarTorrent, modeled the Bit Torrent Protocol Many names for it, in our project, its CarTorrent, modeled the Bit Torrent Protocol

Problem How does a car discover its peers and know their addresses? How does a car discover its peers and know their addresses? What should be the address of the car? What should be the address of the car? How can a file be broken up into smaller pieces to be distributed out among the peers interested in downloading it? How can a file be broken up into smaller pieces to be distributed out among the peers interested in downloading it? How to efficiently and dynamically track file availability and transfer behavior? How to efficiently and dynamically track file availability and transfer behavior?

A two-layer approach : A two-layer approach : AODV lower layer performs route maintenance tasks and discovery of neighbors AODV lower layer performs route maintenance tasks and discovery of neighbors CarTorrent exploits the info provided by lower layer to grab or send files from/to peers CarTorrent exploits the info provided by lower layer to grab or send files from/to peers Our Solution AODV Routing Layer( and Discovery ) CarTorrent Application

Architecture RecvPacketThread Client ReceiveGossipThreadSendGossipThreadFileSplitter RecvPacketThread ListenThread RecvPacketThread CarTorrent File Manager

Components Client: Client: A tabbed frame that encapsulates information for subcomponents A tabbed frame that encapsulates information for subcomponents 3 tabs; share, download, and search 3 tabs; share, download, and search FileSplitter: FileSplitter: Splits a shared file into parts Splits a shared file into parts Combines downloaded parts into a file Combines downloaded parts into a file CarTorrent File Manager: CarTorrent File Manager: Keeps track of pieces of files from gossips Keeps track of pieces of files from gossips Includes the algorithms to find rarest pieces, closest pieces, and rarest closest pieces Includes the algorithms to find rarest pieces, closest pieces, and rarest closest pieces

Components (cont.) SendGossipThread: SendGossipThread: A thread that sends gossip msgs periodically A thread that sends gossip msgs periodically Two types of gossips: Two types of gossips: Gossips originated from itself Gossips originated from itself Gossips received from nearby neighbors Gossips received from nearby neighbors Gossips received from nearby neighbors are sent based on probabilities assigned to interesting and not interesting gossips Gossips received from nearby neighbors are sent based on probabilities assigned to interesting and not interesting gossips Gossips are interesting if client wants the file Gossips are interesting if client wants the file Gossips are not interesting if the client does not Gossips are not interesting if the client does not ReceiveGossipThread: ReceiveGossipThread: A thread that unblocks when receiving a gossip A thread that unblocks when receiving a gossip Discards the gossip if from itself else queues the gossip Discards the gossip if from itself else queues the gossip Gossips are sent to CarTorrent File Manager for managing Gossips are sent to CarTorrent File Manager for managing

Components (cont.) ListenThread: ListenThread: Listens for incoming download request Listens for incoming download request Spawns a RecvPacketThread to process incoming packets Spawns a RecvPacketThread to process incoming packets RecvPacketThread: RecvPacketThread: Processes the incoming packets based on packet type Processes the incoming packets based on packet type If packet type == DATA_REQ, send parts that are requested If packet type == DATA_REQ, send parts that are requested If packet type == DATA, write the data to the local file-system and combine it if all parts have been received If packet type == DATA, write the data to the local file-system and combine it if all parts have been received

Implementation Details AODV based on open-source Linux implementation from Uppsala University in the Netherlands AODV based on open-source Linux implementation from Uppsala University in the Netherlands CarTorrent layer written in Java with a GUI interface to browse/share/download files CarTorrent layer written in Java with a GUI interface to browse/share/download files

Choosing the peer for the file Rarest-Closest First Strategy Rarest-Closest First Strategy Download the rarest piece from the closest peer Download the rarest piece from the closest peer Analyzed to be better than the conventional Bit-Torrent rarest piece only without worrying about proximity of peers [1] Analyzed to be better than the conventional Bit-Torrent rarest piece only without worrying about proximity of peers [1]

Demo Series of pictures demonstrating the sharing of a picture file from one source to two clients Series of pictures demonstrating the sharing of a picture file from one source to two clients Three laptops( two running Linux, one with Windows) Three laptops( two running Linux, one with Windows) If you are interested in seeing the live demo, do drop by BH4681 If you are interested in seeing the live demo, do drop by BH4681

The nodes

Lets share this file

Sharing the file

Sharing the file

Browsing the shared file

Downloading the file

View the downloaded files Rate(Mbps)

Future Work Variable piece length to adapt to clients bandwidth Variable piece length to adapt to clients bandwidth Test in environments with larger distances between nodes (true multi-hop) Test in environments with larger distances between nodes (true multi-hop) Add a mechanism to detect the absence of a file in the network by either: Add a mechanism to detect the absence of a file in the network by either: expiring file pieces (after no gossips) expiring file pieces (after no gossips) sending out explicit leaving gossip msgs sending out explicit leaving gossip msgs Being able to identify failed transfers and get same file piece(s) from other nodes Being able to identify failed transfers and get same file piece(s) from other nodes

Conclusion Implementation of Car Torrent and tested on a real ad-hoc platform Implementation of Car Torrent and tested on a real ad-hoc platform Simple GUI interface simulates what the real system can be Simple GUI interface simulates what the real system can be Java implementation means that the system can be deployed cross-platform Java implementation means that the system can be deployed cross-platform

Related Work Vehicular Sensor Networks Vehicular Sensor Networks CarTel : MIT CarTel : MIT MobEyes : UCLA MobEyes : UCLA SPAWN : UCLA SPAWN : UCLA Scalable co-operative downloading of data among vehicles Scalable co-operative downloading of data among vehicles

References [1] A. Nandan, S. Das, G. Pau M.Y. Sanadidi and M. Gerla. Cooperative Downloading in Vehicular Ad-hoc Wireless Networks. [2] Sundaram Rajagopalan and Chien-Chung Shen. A Cross-layer Decentralized BitTorrent for Mobile Ad hoc Networks.

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