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Non GBR bearers the total bandwidth calculation

+3 votes
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I was trying to understand and implement basic version of 29.213 Section 6.3 QoS parameter mapping Functions at PCRF especially for non GBR bearers.

Non GBR bearers have QCI, ARP, APN-AMBR and UE-AMBR. And also MBR associated with each bearer in the PGW..So when a new bearer is added, the UE and Ennode-b dynamically take care that total rate of all bearers doesnot exceed APN-AMBR (for each APN) and UE-AMBR for all Non GBR bearers in UE..

So not sure PCRF can alter any params related to BW in case of non GBR.. This is my understanding..If you have any comments will be very helpful.

posted Oct 26, 2015 by Pdk

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1 Answer

+2 votes
 
Best answer

Hi Priya,

First of all a non-br bearer in LTE will not have any MBR associated to it. It is part of 3GPP-GPRS access type not E-UTRAN.

APN-AMBR you have mentioned correctly is based on the APN and will be shared between all the non-gbr bearers for a given APN.

UE_AMBR is parameters that is taken care by eNodeB. It tells the total APMBR that UE can get and this value can be shared across all the non-gbr bearers of all the pdns.
Yes, PCRF can very well alter the APN-AMBR at any given point of time based on the subscription of the user or other network related parameters.

Regards,
Peeyush Sharma

answer Oct 28, 2015 by Peeyush Sharma
Thanks a lot Peeyush, :)

The CCR (as part of attach request ) has the Default-EPS-Bearer-QoS, which inturn contains the QCI, and Allocation-Retention-Priority (which is got from the HLR by the MME) .. But somehow doesnot include the APN-AMBR subscribed..Not sure if it is hidden inside any other AVPS..This is because it is easier to get these subscription data from CCR, rather than querying SPR (or HLR , if it is remote HLR via diameter).

Hardcoding APN-AMBR is PCRF is may be basic initial option. But I think it needs to make sure that the subcribed one is not exceeded while allocating ..

~Priya
commented Oct 28, 2015 by Pdk
Requested APN-AMBR will come in CCR-I in QoS-Information AVP
commented Oct 28, 2015 by Peeyush Sharma
Thanks a lot Peeyush..yes i.e requested APN-AMBR.
I was wondering, is there anyway for the subscribed APN-AMBR to pass through CCR, (like Default EPS Bearer QOS, is filled from the subscribed info from the HLR)
commented Oct 28, 2015 by Pdk
It seems you have not read my above comment carefully. Requested or subscribed AMBR will go in QoS-Information in CCR-I and the authorized one will come back in the same AVP in CCA.
If PCRF does not send the QoS-Information AVP in CCA then PGW will consider the requested one as authorized AMBR

Regards,
Peeyush Sharma
commented Oct 28, 2015 by Peeyush Sharma
Yes you are right..I was thinking the "attach request" msg contains some info regarding the "requested APN-AMBR" by the UE..I have not looked in depth about the GTPcV2 messages exchanged b/w mme, sgw and pgw. So I thought "Requested APN-AMBR" comes from the UE, like the requested QOS in the Bearer Resource command..
Just to reiterated what you said
If the requested APN-AMBR is same as the subscribed, PCRF does not need to access the HLR..So it can authorise any value below the subscribed-AMBR when sending the CCA.
commented Oct 28, 2015 by Pdk
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