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Reliable Transfer on Wireless Sensor Networks

Reliable Transfer on Wireless Sensor Networks. Peyman Nayeri Feb 2006. Basic Concept. Many applications exist that require lossless transmission of all data Our goal is to increase the number of received packets. number received = P success * number transmitted

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Reliable Transfer on Wireless Sensor Networks

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  1. Reliable Transfer on Wireless Sensor Networks Peyman Nayeri Feb 2006

  2. Basic Concept • Many applications exist that require lossless transmission of all data • Our goal is to increase the number of received packets. • number received = Psuccess * numbertransmitted • End-to-End retransmission used in TCP • Link-level retransmission for wireless

  3. Possibilities • Redundancy • Erasure Code • Generalization of Parity Code • M+R instead of M+1 • Alternative next hop

  4. Goal of this Paper • Examine techniques which can be used in multi-hop routing schemes. • These techniques can be used alongside other models which concentrate on convergence, divergence or point-to-point • Optimization for nodes with very limited resources

  5. Necessity of Link-Level Retransmission • With a 10% loss rate after 15 hops the chance increases to 80% • RTT for end-to-end retransmission needs to use an over-estimated upper-bound which results in the sender holding its buffer for a long period

  6. Reviews • Erasure Code • Linear Code • Vandermonde Matrix • Reed-Solomon Code • Modifications for WSN • Extension Fields • Systematic Code • Multiple Independent Code Words in a packet • Operation Table

  7. Alternative Route • Why? • Erasure Coding • Link-Level retransmissions • Detecting the failure • Using an alternative route • BVR (Beacon Vector Routing)

  8. Flexibility of BVR • Normal Mode • Greedy-routing procedure • Fallback Routing Mode • Beacon closest to the destination is chosen • Beacon then initiates a scoped flood • Choosing a close beacon minimizes the flood scope

  9. Experiments & Results • Good explanation as to why the encoding and decoding process won’t add to the delay • Link-level retransmission should be used in every case • Erasure codes are useful because they don’t require all packets to be delivered to recover the data

  10. Experiments & Results • Route fix solves stale routing table problem, providing quick adaptation to link failure. • Also increases usefulness of erasure code, which does not work well with successive losses.

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