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...ate of candidate neighbors lets a protocol choose the most energy efficient next routing hop. The earliest sensornet link estimators assumed link symmetry, establishing routes either through flooding =-=[5]-=- or snooping [7]. Later it was shown that this assumption was invalid and it led to terrible performance. Second generation estimators [13] used packet sequence numbers to count lost packets, but requ...

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...ed link symmetry, establishing routes either through flooding [5] or snooping [7]. Later it was shown that this assumption was invalid and it led to terrible performance. Second generation estimators =-=[13]-=- used packet sequence numbers to count lost packets, but required a low rate of control traffic to ensure that nodes could detect when links died. While this approach can detect good links, it adapts ...

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...eir experimental methodology differs from those of the sensor network studies. For example, they consider average SINR ratios over secondlong periods rather than on a per-packet basis. Polastre et al =-=[8]-=- presented preliminary evaluation results for Telos motes (based on CC2420) and suggested that the average LQI was a better indicator of PRR and that RSSI was a bad indicator. We believe that the corr...

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...I, which is the strength of a received RF signal. Conventional wisdom in the sensornet community says that RSSI is not a good indicator. This belief is based on experimental work with early platforms =-=[14]-=-, which showed that while detecting good links was possible with RSSI, with imperfect links it is difficult to make good estimates. Many current platforms — e.g., the micaZ, Telos, and Intel Mote2 — u...

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...al to interference and noise ratio (SINR) threshold was different for different nodes and that it also depends on the RSSI. They suggested that these were due to hardware miscalibration. Aguayo et al =-=[1]-=- observed similar packet delivery behaviors in 802.11 networks, but concluded that they were most likely due to multipath effects as there was little correlation between PRR and SINR. However, their e...

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...any researchers have done thorough evaluation of previous generation motes with radio chips TR1000 [9] and CC1000 [3]. We briefly present some of these works and then introduce our own. Ganesan et al =-=[4]-=- analyzed performance of Rene motes (based on TR1000) and showed that even a simple algorithm such as flooding had significant complexity at scale. They attributed this complexity partly to the link ...

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...onal hardware indicator, LQI, which is effectively a measure of chip error rate. The observed limitations of RSSI in earlier platforms, combined with radio homogeneity, has led several routing layers =-=[12,11]-=- to adopt LQI, based on the last packet, as the indicator of choice. Despite its wide adoption, as far as we are aware there has so far been no evaluation of whether LQI is a good indicator. In this p...

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... neighbors lets a protocol choose the most energy efficient next routing hop. The earliest sensornet link estimators assumed link symmetry, establishing routes either through flooding [5] or snooping =-=[7]-=-. Later it was shown that this assumption was invalid and it led to terrible performance. Second generation estimators [13] used packet sequence numbers to count lost packets, but required a low rate ...

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...suggested that these asymmetries were due to sensitivity mismatch at different nodes. Woo et al [13] also confirmed a ”transitional” region where the PRR had no correlation with distance. Cerpa et al =-=[2]-=- also showed that there was no correlation between PRR and distance beyond 50% of a node’s communication range. They also found many link asymmetries (up to 30%). They showed that these asymmetries we...

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... packet delivery of Mica motes (based on TR1000). From their measurements without any encoding they showed that links with PRR of at least 95% had high RSSI while the converse was not true. Son et al =-=[10]-=- analyzed concurrent packet transmissions for mica2 motes. They showed that the signal to interference and noise ratio (SINR) threshold was different for different nodes and that it also depends on th...