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SRVCC Sv interface, SRVCC PS to CS Request message contentsSRVCC

+3 votes
613 views

PS TO CS message over the Sv interface is supposed to carry the info regarding the Voice bearer.

But from the contents of it, I don't see anywhere this info is sent in this message.
I am looking this from the MME perspective.

From the spec and our legacy untested code , i see that following fields are present.

1) IMSI
2) MME Sv Address for Control Plane
3) MME Sv TEID for Control Plane
4) MSISDN
5) STN-SR
6) MM Context/ MME UE context
7) Source to Target Transparent Container

I am clear about the fields upto 5). Also the ENodeB sends the 7) Source to Target Transparent Container to MME. and MME simply transparently sends in the PS2CSRequest. But what about the 6).

Any sample message is also very helpful.

posted Jan 28, 2015 by Pdk

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looks like sample message could be a propitiatory info and less likely someone will share on public platform.

Point 6 is MM context which is applicable to all handover cases, not sure how to answer this.

may be post small small queries and may be we can get clues.
yes i.e true..i was not looking for each ie and its values..just a broad level overview of what might be sent in PS2CSReq.
As i was looking into spec, i found that above fields are present.
But none of them seem to contain specific info regarding the  CS bearer.
Thats true, I am not having the sample packet. Not sure if people would be able to share such thing or not but seems to be less likely :)
Yes sample packet is secondary.

My actual doubt is regarding spec (spec clarification). Which IE is containing info reg the CS bearer. I went through the spec 29.280. But spec is not very clear. Coming from the long 3g(2g) UE background, it takes time to pick up the n/w side, lte and all specs. Quite a effort . Thanks for this forum especially for quick responses
This is what 29.280 is saying about the MM context

MM Context for EUTRAN SRVCC
The MME shall include mobile station classmarks, supported codecs, and CS Security key in MM Context for SRVCC for E-UTRAN SRVCC.
The derivation of the CS security keys shall follow the procedures defined 3GPP TS 33.401.

MM Context for UTRAN SRVCC
The SGSN shall include mobile station classmarks, supported codecs, and CS Security key in MM Context for SRVCC for UTRAN (HSPA) SRVCC.
The derivation of the CS security keys shall follow the procedures defined 3GPP TS 33.102.

I hope this should be helpful for guessing the IEs
Thanks Salil. MM context looks generic info. I am not sure how the CS bearers map to the lets say RAB (in case of 3g). Lets say we have 2 CS bearers and how they are mapped back in 3g.
I donot see any set of IEs, carrying info abt different Bearers.
May be my Q looks odd coming from UE side
could not get anything, looks that things getting mixed. Will you like to ask fresh query so that it goes to large audiences also.
Any update ???
Sorry was away from sometime..May be I will ask a fresh query, by doing some homework of digging deeper into specs
Fine thanks :)

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