Solution to LTE throughput degradation once 5G-NR DC addition procedure enabled

5G NR
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  • Q. LTE Throughput have been degraded once 5G-NR DC configured?

  • A. In NSA deployment, 5G Secondary node addition have been configured during normal LTE-ERAB_Setup progress in RRC_Connection_Reconfiguartion once UE_Capability information include UE-MRDC-Capability , SupportedBandListNR-r15 IEs.

5G Secondary node addition means UE that camped on LTE will enter MR GAP configured via RRC_Connection_Reconfiguartion to measure 5G-NR Cell and triggering B1 event as shown below.

Problem here is that for UEs that did not locate in 5G-NR coverage will continuous config LTE GAP pattern forever as not suitable 5G NR coverage can get to report event B1. This behavior will degrade LTE user throughput around 25% as shown below.

Note that for UE that support 5G inter-system measurements without Measurement Gaps have no effect on LTE throughput degradation. But not all UEs may support this , many UEs would be unable to complete 5G measurements if Measurement Gaps are disabled.

Solution:

  • Design LTE cell edge coverage to align with 5G-NR Scell-addition coverage as possible.
  • Specify timer to allocate measurement gaps only for the first 3Sec of a RRC connection then end MeasureGap after 3Sec expiration.
  • Define how long the B1 measurements are going to be active, and if deactivated, how long it will take to reactivate the B1-NR measurements.

Solution to LTE throughput degradation once 5G-NR DC addition procedure enabled

Solution to LTE throughput degradation once 5G-NR DC addition procedure enabled
Solution to LTE throughput degradation once 5G-NR DC addition procedure enabled936×401 81.5 KB

Solution to LTE throughput degradation once 5G-NR DC addition procedure enabled

Reference: Telefonica

LinkedIn: Fathi Farouk on LinkedIn: #optimizationhassle #5g #5gtechnology #5gnr #5gnetwork #optimizationhassle

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That’s was very informative
Thanks brother for sharing this

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Good one article!

As mentioned few UE sab support 5G inter system MR without m-gap.

Not sure any such device available and how they fine tune frequency without any gap.

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Hello Experts.

Have you faced gradual LTE Initial eRAB SR degradation once 5G NR users being increased?

Ericsson system, 5G NSA.

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does the degradation concern LTE only users or DC users, u can try the Flex Counters, or check Fail due to UE Cap pmEndcSetupFailUeCap, may be the degradation is due to some UE capability in DC