eMBMS in libqmi

[Reinhard Speyerer]

On Mon, Jan 29, 2018 at 01:07:54PM +0000, Ginzler, Tobias wrote:
> Yes, the TMGI stuff is probaby needed to subscribe to a
> certain channel/group. I miss some messages which define
> where the actual broadcast data is expected once the
> subscription is done by the UE. At least 2 operators

Hi Tobias,

my guess is that WDSStartNetworkInterface TLV 0x34
(ExtendedTechnologyPreference) set to eQMIWDSExtendedTechPrefs_EMBMS
is supposed to be used for this, perhaps using some form of
IP tunneling(?).

Since the MC74xx/EM74xx data sheets do not seem to mention eMBMS as a
supported feature I have some doubts however to what extent you could
make eMBMS work with them (at least with the currently available firmware).

A corresponding QMI trace from an eMBMS-capable Android phone with a
Qualcomm chipset obtained in your lab network would really be helpful
as a reference.

> (S.-Korea: KT, USA: Verizon) according to this document
> https://gsacom.com/paper/lte-broadcast-embms-global-status-summary-deployments-activities/
> offer commercial eMBMS service today. I would define the
> messages in the data/ directory but I have no
> documentation on the message format. If you have some
> documentation, please share and I can try adding the
> messages.
> 

In the Gobi API (latest version available from
https://portland.source.codeaurora.org/patches/quic/gobi/Gobi/
is GobiAPI_2013-07-31-1347.tar.gz, also available in libqmi git)
it is usually the easiest to use the Gobi API method (e.g. NASConfigureEMBMS)
in GobiConnectionMgmtAPI.h as a starting point and look up the corresponding
TLVs in GobiConnectionMgmtAPIStructs.h by the method name.

Please check that the EM7430 correctly detects your lab network to have
eMBMS coverage in qmicli --nas-get-system-info output before proceeding.

Good luck!

Regards,
Reinhard

> >> What we need is to extend libqmi and qmicli with support for the
> >> QMI_NAS_CONFIG_EMBMS (NAS 0x0062), QMI_NAS_GET_EMBMS_STATUS (NAS
> >> 0x0063) and QMI_NAS_EMBMS_STATUS_IND (NAS 0x0063) messages. The
> >> messages are easy enough (just enable/disable eMBMS setup). We would
> >> need to define them in data/qmi-service-nas.json and then update
> >> qmicli with new actions to use them.
> 
> >Note that there are a few WDS eMBMS TMGI requests as well. Might also be
> >required for eMBMS support?
> 
> >QMI_WDS_TMGI_ACTIVATE (WDS 0x0065)
> >QMI_WDS_TMGI_ACT_IND (WDS 0x0065)
> >QMI_WDS_TMGI_DEACTIVATE (WDS 0x0066)
> >QMI_WDS_TMGI_DEACT_IND (WDS 0x0066)
> >QMI_WDS_TMGI_LIST_QUERY (WDS 0x0067)
> >QMI_WDS_TMGI_LIST_IND (WDS 0x0068)
> >QMI_WDS_TMGI_SWITCH (WDS 0x0088)
> >QMI_WDS_TMGI_SWITCH_IND (WDS 0x0088)
> 
> >I know exactly nada about this broadcast stuff.  Thought that was a
> >thing of the previous millemnnium ;-) But TMGI seems to be a way to
> >uniquely name a broadcast service using the MCC and MNC to make it
> >globally unique.  Ref https://hal.archives-ouvertes.fr/hal-01291201/document
> >So I am guessing that the WDS requests are what actually activates a
> >service?