Pump-slowly, fetch-quickly (PSFQ): a reliable transport protocol for sensor networks

Transport Protocols for Wireless Sensor Networks: State-of-the-Art and Future Directions

“…Pump Slowly Fetch Quickly (PSFQ) [7] is a transport layer protocol, designed specifically to meet the unique resource challenges presented by WSNs with a focus on point-to-multipoint FIGURE 2 DTC caching performs aggressive hop-by-hop recovery when loss is detected; however, if the lost packet has been removed from cache, the NACK must be forwarded on potentially to the destination.…”

“…To address the shortcomings of gap detection, PSFQ uses a "proactive fetch" [7] scheme that allows it to set a timer that starts from the receipt of the last message until the next message is received. This continues while the total size of the received data segments is less than the file size specified in the header field of the inject message.…”

“…No congestion, Low reliability (NC, LR) f < f max and η < 1 -∈ No congestion, High reliability (NC, HR) f ≤ f max and η > 1 + ∈ Congestion, High reliability (C, HR) f > f max and η > 1 Congestion, Low reliability (C, LR) f > f max and η ≤ 1 Optimal Operating Region OOR f < f max and 1 -∈ ≤ η ≤ 1 + ∈ problem in dense sensor networks [7]. For example, with 10% physical layer loss, the success rate of delivering a message across only seven hops is approximately 50%.…”

A Study on Data Aggregation and Reliability in Managing Wireless Sensor Networks

“…Retransmissions can be used to improve reliability: as shown for PSFQ in [14], hop-by-hop error recovery is significantly more effective than endto-end recovery in a wireless environment. For a WSN environment, data aggregation does not effect reliability in terms of the number of reports received at a root node from a source (the expected value) when compared to the non-data aggregation case [15].…”

“…There are two way to try and ensure maximum end-to-end reliability in a WSN: sending the same datum multiple times in a stream, thus increasing the probability that at least one of the instances will be received [9][10]; and sending the datum once ("one-shot") with acknowledgements and local re-transmissions [14] to improve the probability that an unduplicated data instance will be received. As we show in our results, a "one-shot" response results in significantly less traffic.…”