SGSN Inter RAU Throughput Problem

[kema2103]

Hi,

we are facing with the following problem:


1. PDP session established under ZTE SGSN 3G coverage.  Average DL speed e.g. 14,4 Mbit (HSDPA)

2. InterSystem/SGSN change to NSN SGSN (2G coverage) DL speed decreased from 14,4 Mbit to approximately 200 Kbit (GPRS/EDGE)

3. InterSystem/SGSN change back to 3G coverage of ZTE SGSN. Previous location. DL speed max 472 Kbit or 2048Kbit. Depending on PRFILE settings on NSN side but 14,4 Mbit are not possible anymore!

4. After session disconnect and reconnect, 14,4 Mbit DL speed possible again.

and following QoS profile parameters were used:

Taken from NSN Feature description, SG02104 and SG02198: HSDPA Support and HSPA+ (DN05196878).

Downlink bit rate in ISHO and GERAN PDP context activation
The handling of the quality of service downlink bit rate values in inter system handovers and GERAN PDP context activation can be chosen with the two PRFILE parameters:
• Parameter 002:1518 OVERRIDE 2G DOWNGRADE
• Parameter 002:1519 QOS HANDLING IN ISHO
If both these parameters have the TRUE value then the QOS HANDLING IN ISHO overtakes the OVERRIDE 2G DOWNGRADE parameter.
If both QOS HANDLING IN ISHO and OVERRIDE 2G DOWNGRADE parameters have the FALSE value:
• In the inter system handover to the GERAN, the downlink MBR and GBR values are 472 kbps. In the PDP  context activation with the GERAN, the downlink MBR and GBR maximum values are 472 kbps.
• Downlink bit rates are not renegotiated in the inter system handover to UTRAN.

If the OVERRIDE 2G DOWNGRADE PRFILE parameter has the TRUE value and the QOS HANDLING IN ISHO parameter has the FALSE value:
• In the inter system handover to the GERAN or in the PDP context activation with the GERAN, the downlink  MBR and GBR values are 2048 kbps.
• Downlink bit rates are not renegotiated in the inter system handover to UTRAN.

If the QOS HANDLING IN ISHO PRFILE parameter has the TRUE value:
• In the inter system handover to the GERAN or in the PDP context activation with the GERAN, the operator- configurable IMBR and IGBR parameters are taken into account in negotiating the quality of service downlink  bit rate parameter values.
• Downlink bit rates are renegotiated in the inter system handover to UTRAN.

Whatever QoS combination is used max. achieved throughput is 2 Mbps.

does anyone from you has experience with this problem and could probably provide some hints or solutions on this problem?

thanks.

[hengbong]

Kema,

Did u reach a solution for this problem? Coz I am facing a similar one right now.

I have an MBR problem with a certain APN only. 3G SGSN sometimes creates a PDP context with MBR=472 kbps for this APN only although user profile supports MBR=8064kbps. Tracing the user shows that he sometimes gets 472kbps and other times 8064kbps.

-If a PDP created with MBR=8064kbps, it is downgraded in 2G to 472kbps then upgraded in 3G again to 8064kbps. (QoS handling in ISHO is set to TRUE)
-If a PDP created with MBR=472kbps, the same MBR remains unchanged through mobility.

Thanks,