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Re: Questions and comments on CH

From: Göran Eriksson AP <goran.ap.eriksson@ericsson.com>
Date: Wed, 30 Mar 2016 15:00:37 +0000
To: Ilya Grigorik <ilya@igvita.com>
CC: HTTPWG <ietf-http-wg@w3.org>
Message-ID: <D3212FA3.2366B%goran.ap.eriksson@ericsson.com>
Hi Ilya,

Tnx for response. See below for some answers

>Depends on how the OS surfaces this. As an example, Chrome for Android
>relies on ConnectivityManger.CONNECTIVITY_ACTION [1]. When we receive the
>intent, we query TelephonyManager.getNetworkType() [2] and, if a change
>has occurred, fire the appropriate
> NetInfo event in the browser. For more, see [3]. So, in this case, the
>question really boils down to: how does Android react to such "micro <>
>macro" handovers? ... Honestly, not sure! :)

Murky area this, agree. If we wanted to get this straight in the future,
we would need to engage with device OS vendors, modem vendors and
eventually…(drum roll)…3GPP. But that’s another discussion for another
(TPAC) day perhaps!

>The CH draft refers to the “Network Info API” which states:
>"Where possible, this value may be refined to report a more accurate
>upper bound based on current properties of the interface - e.g. signal
>strength, modulation algorithm, and other "network weather" variables.”
>This can mean several things including the client/UA measuring,
>calculating, prediction, getting network feedback and updating this
>“network info” very often since the “RAN weather” can change often indeed?
>Indeed! FWIW, existing implementation in Chrome doesn't do this. We do
>have an open issue for this: https://github.com/w3c/netinfo/issues/30 -
>if you have any thoughts or recommendations,
> please chime in!

Thanks for the pointer- will for sure!

The Downlink hint need should perhaps be clear on if it relates to
theoretical DL rate or “actual/measured/recommended”, some way of
signalling this to the server seem beneficial since the actions of it may

>Is this applicable to the CH Downlink? Or will CH Downlink “only” reflect
>the theoretical downlink capacity of the network (technology) it is
>connected to?
>The intent is to mirror the same value as reported by downlinkMax at the
>time the request is created.

Thanks. This of course can be used such that the client updates the server
as the situation changes but that could be up the application to decide
whether to do or not.


Received on Wednesday, 30 March 2016 15:01:53 UTC

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