Worst throughput with CA

4G LTE
,
1

Hi Experts,
We are running a test of LTE carrier aggregation.
We have L1 which is 2100-20 MHz and L2 1800-10 MHz.
All CA Features are activated.
But the throughput is much worst even without CA.
Any suggestions?

1 Like
2

Check your CA combo. Is this band supported in UE capability?
Check mimo layers combo.
Are you seeing 4G+ symbol?
Scell layer RSRP, throughput on screen?
Can you share snapshot of tool having CA window?

3

Which device? First thing, check UE capability report for CA.

4

We have L18 and L21 Combination and it works fine.
Please make sure both the layers are in the same BBU. Else we need separately feature for having sCell on another BBU.

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5

But did you get the RRC reconfig for sCell?

6

I am not sure, need to check.
This is the first time we are activating this feature.
Vendor is Ericsson.

7

First you need to get rrcrconfig for sCell.
Then act/deact is done via MAC CE.

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8

Please check bellow:

  1. UE CA support for said band/BW combination.
  2. Check RRC Reconf for SCell addition/ SCell measurement reporting.
  3. Check MR sent for SCell addition if blind addition is not there.
  4. Check SCell addition after MR (SCellTAddMod).
  5. Check Scell activated or not (Buffer threshold configuration value to set properly).

Also check Ericsson specific eNb configuration for CA.

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9

Check sCell activation: is it buffer based or blind?

10

Concerning improving the performance of carrier aggregation
below changes should be recommended:

  1. Parameter: waitForCaOpportunity change from 10000 (10 sec) to 1000 (1 sec) in order
    to speed up UE for Carrier Aggregation consideration
  2. Parameter: sCellScheduleSinrThres change from 0 to -10 in order to consider the UE for
    CA even at lower SINR of SCELL.
  3. Parameter: sCellActProhibitTimer change from 200 to 100 msec in order to have a
    quicker Activation of SCELL.
  4. Parameter: sCellActDeactDataThres keep at -1
  5. Parameter: caUsageLimit keep at 300
  6. Parameter: caPreemptionThreshold change from 50 to 70 to keep considering SCELL for
    CA even when load is 70%
2 Likes
11

Brother, is there any way we can control the CA coverage by RSRP? is there any parameter related to coverage other than SINR?

12

a1a2ThresholdRsrp : This threshold is closely related to the activation/deactivation threshold sCellScheduleSinrThres

setting a1a2ThresholdRsrp is based on the following principles:

  • A SCell should not be deconfigured while it is still activated.
  • When a SCell is deactivated due to poor channel conditions, the SCell should be de configured to free up resources.

There are, however, situations that warrant setting the **[a1a2ThresholdRsrp] differently. For example, if there is only one SCell candidate in the deployment and the cell loading is low, then [a1a2ThresholdRsrp] could be set to a very low value to avoid deconfiguring the SCell when the UE is out of coverage.This will reduce RRC signaling and the SCell can quickly be reactivated when the RF condition improves.

13

In samsung, a4 rsrp threshold is there for scell addition which can b controlled to make more/less scell additions