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doc: thread: SSED and device type updates #11619
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@@ -55,7 +55,19 @@ Comparison of SED and SSED | |||||
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Compared to an SED, an SSED has no drawbacks for transmission and provides reduced power consumption and network traffic. | ||||||
This means you should configure your SED devices as SSEDs whenever possible. | ||||||
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Based on the SED and SSED characteristics, use SSED for cases that meet one or more of the following criteria: | ||||||
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* You need a small latency (ensured by small poll period for SEDs or small CSL Period for SSEDs). | ||||||
As a general rule, SSED is a viable option and may decrease power consumption if the CSL Period is small (less than 20 seconds) and the parent has decent CSL Accuracy. | ||||||
* You want to have similar or smaller power consumption than with SED. | ||||||
There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. From what I understand, SSEDs are viable to use only when the added code and complexity are justified by the lower power usage. Frequent polling (eg. at least every 20s as proposed by Eduardo) makes the device a candidate to be a viable SSED, given the device and parent uncertainty (among other parameters) is good enough - so the decision whether to use SSED still requires some application-specific data. There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. @LuDuda , any opinions about Piotr's proposal? There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. Good suggestions from Piotr. In general I'm a bit afraid to "recommend" SSED role blindly for manufacturers even if latency is less than ~20s. The whole Thread/Matter ecosystem is not yet fully ready. I would say that the default option is SED. However, SSED is great when it's parent has small CSL uncertainty as well accuracy. We don't have an example in SDK, but customer may use information about parent's CSL parameters (uncertainty and accuracy) to switch to SSED role or not. This can be done just after attachment dynamically. In general what Piotr suggested is great. E.g. that SSED is viable option and may decrease power consumption in case the CSL interval is small (~<20s) as well as parent has decent CSL parameters. |
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* You want to reduce over-the-air radio traffic in an environment with many SEDs. | ||||||
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In short, SSEDs are viable only when the additional application code and complexity to handle the more frequent polling are justified by the lower power usage or less intensive radio channel usage (or both). | ||||||
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For example, one specific market application of SSEDs could be window coverings. | ||||||
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For this use case to work as an SSED, the blinds must be very responsive (for example, with a latency within 500 ms), while the data must be very rarely exchanged between the controller device and the window covering device. | ||||||
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You can see the difference in power consumption on the :ref:`Thread power consumption <thread_power_consumption>` page. | ||||||
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.. figure:: overview/images/thread_sed_ssed_comparison.svg | ||||||
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In last sentence.. i want to say that FED relieves its partent from doing things on behalf of the child. This is the main advantage of FED.