Mapping MBIM HighestAvailableDataClass to MM property

[Ben Chan]

On Wed, Apr 16, 2014 at 3:18 AM, Aleksander Morgado <
aleksander at aleksander.es> wrote:

>
> Yeah, I believe I remember about HighestAvailableDataClass... Can you
> provide some examples on e.g. what the values are for
> HighestAvailableDataClass and AvailableDataClasses during a
> connection? My assumption, IIRC, was that AvailableDataClasses is
> always the current one and HighestAvailableDataClass is the best one
> the network can provide, even if it currently may not be that one.
>
>
I found that this is yet another unclear area in the MBIM spec. Modem
vendors seemed to have different interpretations / implementations as well.
I'm still in the process of gather information on various modems.

My interpretation of the spec is:
- AvailableDataClasses indicates the available data classes supported by
the cell that the modem is currently registered in.
- HighestAvailableDataClass indicates the highest data class in the current
cell, either at packet attach or after a context is activated

which seems to imply:
- After the modem registers to a cell, we can get a list of data
classes "supported"
by that cell via AvailableDataClasses.
- After the modem activates a context (or in some cases after attaching to
a packet service) within the currently registered cell, we can get the
highest data class that is "allowed" by that cell via
HighestAvailableDataClass, which should be one of the values listed in A
vailableDataClasses.

However, I'm not sure whether HighestAvailableDataClass could change while
the modem remains connected to the same cell and what happens during a cell
handover. Suppose HighestAvailableDataClass is always updated to indicate
the highest data class in AvailableDataClasses, it seems more accurate to
update AccessTechnology based on HighestAvailableDataClass.

I wonder what's the appropriate channel to get clarifications on the spec.
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