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This RTT sample reflects both propagation and queuing delays experienced in the network path.
Because IoT links (e.g., IEEE 802.15.4, 6LoWPAN) often exhibit non-stationary latency patterns caused by duty cycling or interference, the algorithm continuously updates its timing estimate after every transaction rather than relying on static intervals.
To obtain a stable, yet responsive estimate, two key metrics are maintained
(i)Smoothed Round-Trip Time (SRTT) - a weighted moving average of recent RTT samples and (ii) RTT Variance (RTTVAR) - an estimate of network delay fluctuation.
Both recursively and probabilistically computed with some pre-established 𝛼, 𝛽, and 𝜅 values for stability, reactivity, and confidence margin respectively.
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IEEE/ICACT20260196 Slide.22
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