Using TriScale for ETX
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Andreas Urke
Mar 13, 2022, 4:23:57 PM3/13/22
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Hi,
this is not exactly a question on Triscale directly, but more on a challenge of a particular usage of TriScale. Feel free to remove if deemed off-topic.
I was playing around with ETX as metric. I define ETX as attempted transmissions per successful transmission, i.e. num. TX attempts divided by num. successful TXs. Calculating the total ETX for an entire run is thus trivial. However, calculating it over time such that I could utilize TriScale metric-analysis, I met some challenges: The core issue is that transmissions may not succeed, leading to 0 in the divisor. For example, an intuitive approach would be to use ETX per transaction (MAC-layer transmissions and retransmissions of the same packet). Yet the MAC will typically give up, e.g. after 8 attempts - what ETX to set for such a transaction? Similar situations may occur if calculating ETX e.g. per minute.
One option could be to exclude such transactions, and rather catch them in a different metric (like transaction-loss) - this would be somewhat analogous to end-to-end latency and delivery ratio. This does seem precise, but it disperses the information across two values, making comparisons harder.
Another option could be to calculate it across a number of transactions which more or less guarantees there is at least one success, e.g. "ETX per 10 transactions". But introducing such an artificial value may create issues, e.g. it might not be portable to future experiments, making comparison more difficult.
A third option could be to set a fixed high ETX for the transactions, yet as above, such artificial values may be challenging.
Or finally, just calculate ETX across the entire run - losing TriScale features such as the convergence test.
Would love to hear thoughts on this as I suspect there is some angle on the entire problem I am missing. Note that the issue is probably transferable to other metrics as well.
this is not exactly a question on Triscale directly, but more on a challenge of a particular usage of TriScale. Feel free to remove if deemed off-topic.
I was playing around with ETX as metric. I define ETX as attempted transmissions per successful transmission, i.e. num. TX attempts divided by num. successful TXs. Calculating the total ETX for an entire run is thus trivial. However, calculating it over time such that I could utilize TriScale metric-analysis, I met some challenges: The core issue is that transmissions may not succeed, leading to 0 in the divisor. For example, an intuitive approach would be to use ETX per transaction (MAC-layer transmissions and retransmissions of the same packet). Yet the MAC will typically give up, e.g. after 8 attempts - what ETX to set for such a transaction? Similar situations may occur if calculating ETX e.g. per minute.
One option could be to exclude such transactions, and rather catch them in a different metric (like transaction-loss) - this would be somewhat analogous to end-to-end latency and delivery ratio. This does seem precise, but it disperses the information across two values, making comparisons harder.
Another option could be to calculate it across a number of transactions which more or less guarantees there is at least one success, e.g. "ETX per 10 transactions". But introducing such an artificial value may create issues, e.g. it might not be portable to future experiments, making comparison more difficult.
A third option could be to set a fixed high ETX for the transactions, yet as above, such artificial values may be challenging.
Or finally, just calculate ETX across the entire run - losing TriScale features such as the convergence test.
Would love to hear thoughts on this as I suspect there is some angle on the entire problem I am missing. Note that the issue is probably transferable to other metrics as well.
Andreas Urke
Mar 21, 2022, 2:02:28 PM3/21/22
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