Reference Signal Power Boost Trial

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Reference Signal Power Boost Trial
Reference Signal Power Boost
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The Reference Signal (RS) allows the UE to make an estimate of channel conditions over the entire
cell bandwidth.
The UE evaluates in the downlink the quality of the radio link of the serving cell. The UE bases its
evaluation on the cell-specific reference signal relative to thresholds Qout and Qin.
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In L12A ICP5 SPP16 and L12B UM6.1, there is a function to define the RS Power Boost at
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Qout is defined as the level at which the downlink radio link cannot be reliably received. Qin is defined as the
level at which the downlink radio link can be received with significant reliability.
Qout and Qin are defined relative to the block error rate of a hypothetical PDCCH transmission and the
thresholds are defined in 3GPP TS 36.133. The quality of the radio link is evaluated in every radio frame if the
UE is not in Discontinuous Reception (DRS) mode.
If the radio link quality is below the threshold Qout over the period of 200 ms, timer T310 is started, assuming
N310=1. See 3GPP TS 36.133.
At the expiration of the T310 timer, the UE switches off uplink transmission. If the radio link quality is above
the threshold Qin over the period of 100 ms, timer T310 is stopped, assuming N311is set to 1. See 3GPP TS
36.133.
If the UE is in DRS mode, the DRS cycle length dependent evaluation period is used instead, see 3GPP TS
36.133.
3 dB,
1.7 dB or
0 dB (RS Power Boost de-active)
RS Power Boost Parameter Name: deltaPsdRs2Tx
RS power boost (+3dB) is activated by default (current setting in AT&T’s network)
RS Power Boost
TRIAL Framework
Performance Improvement
• Test Environment:
– LA Market
– Rural (may degrade performance with RS Power Boost de-activated)
– One Cluster (~25 eNBs)
• Test Cases: Set RS Power Boost at:
• 3 dB (current)
• 1.7 dB
• 0 dB (RS Power Boost de-active)
– Evaluate the performance of the key KPIs.
• Expected Benefits
– 10-15% DL throughput improvement
• Trial Market (proposed): LA
– Approximately 25 eNBs, L12B
Trial Areas
TRIAL AREA
AREA 2
LA Market, L12B Sites
AREA 1 (see left)
eNB SITES (29)
AREA 1
CLL03239, CLL03240, CLL03241, CLL03242,
CLL03243, CLL03244, CLL03255, CLL03341,
CLL03347, CLL03405, CLL03407, CLL03408,
CLL03409, CLL03412, CLL03413, CLL03417,
CLL03418, CLL03419, CLL03427, CLL03430,
CLL03444, CLL03445, CLL03447, CLL03464,
CLL03649, CLL03650, CLL03652, CLL03665,
CLL03666
The Area 1 is suburban with some office / low industrial buildings.
TRIAL Schedule
Test
Configuration
Date
Description
TC1
Gold Standard
RS Power Boost = 3dB
TC2
11/6/2012
RS Power Boost =1.7dB
TC3
11/15/2012
RS Power Boost =0dB
TC4
12/4/2012
RS Power Boost=1.7dB
TimeToTriggerA2Prim =1280ms
Note: The default value for TimeToTriggerA2Prim is 640 ms
Performance Details
CLL03417_7A_1 Experienced Serious Degradation on Nov 23
As degradations happened to CLL03417_7A_1 on Nov 23, it should be taken into
consideration in the evaluation of the KPI trend according to RS Boost changes.
11/6/2012
TC1: RS Boost=3dB
11/15/2012
TC2: RS Boost=1.7dB
12/4/2012
TC3: RS Boost=0dB
Caused by
CLL03417_7A_
Observations:
1. Total setup successful rate had obvious increase since RS Boost change from 3dB to 1.7dB.
2. Total setup successful rate shows more improvement after RS Boost change from 1.7dB to 0dB.
3. Total setup successful rate increase is caused by RRC and initial RAB setup rate increase.
4. ERAB addition successful rate varies.
TC4: RS
Boost=1.7dB
A2TTT=1280ms
11/6/2012
TC1: RS Boost=3dB
11/15/2012
TC2: RS Boost=1.7dB
12/4/2012
TC3: RS Boost=0dB
TC4: RS
Boost=1.7dB
A2TTT=1280ms
Caused by
CLL03417_7A_
Caused by
CLL03417_7A_
Observations:
1. Erab Drop rate had obvious improvement after RS Boost change from 3dB to1.7dB.
2. Erab Drop rate shows more improvement since RS Boost change from 1.7dB to 0dB.
3. ERAB Drop rate shows increase after reversion to 1.7dB.
11/6/2012
TC1: RS Boost=3dB
11/15/2012
TC2: RS Boost=1.7dB
12/4/2012
TC3: RS Boost=0dB
Caused by
CLL03417_7A_
Observations:
Overall increase in IntraLTE Handover success rate, while no obvious difference
corresponding to RS Boost change from 1.7dB to 3dB.
TC4: RS
Boost=1.7dB
A2TTT=1280ms
11/6/2012
TC1: RS Boost=3dB
11/15/2012
TC2: RS Boost=1.7dB
12/4/2012
TC3: RS Boost=0dB
TC4: RS
Boost=1.7dB
A2TTT=1280ms
Observations:
IRAT rate had obvious increase after RS Boost changes. The change in the A2 time to trigger has
mitigated this effect (TC4). This was a reduction over the TC2 case with the same RS Power
Boost.
11/6/2012
TC1: RS Boost=3dB
11/15/2012
TC2: RS Boost=1.7dB
12/4/2012
TC3: RS Boost=0dB
TC4: RS
Boost=1.7dB
A2TTT=1280ms
Observations:
1.
Increase in DL Throughput after RS Boost change from 3dB to 1.7dB; further improvement after RS Boost change
from 1.7dB to 0dB.
2.
Reduction in DL/UL throughput for TC4. This is attributable to holding the UE longer in bad RF conditions.
11/6/2012
TC1: RS Boost=3dB
11/15/2012
TC2: RS Boost=1.7dB
12/4/2012
TC3: RS Boost=0dB
Observations: DL/UL PDCP trending upward with normal traffic growth.
TC4: RS
Boost=1.7dB
A2TTT=1280ms
11/6/2012
TC1: RS Boost=3dB
11/15/2012
TC2: RS Boost=1.7dB
12/4/2012
TC3: RS Boost=0dB
Observations:
1.
2.
3.
4.
Increase in DL HARQ ACK for QPSK and16QAM after RS Boost change from 3dB to 1.7dB.
More improvement in DL HARQ ACK for QPSK and 16QAM after change from 1.7dB to 0dB.
64QAM ACK has no obvious change.
Reduction back to 1.7dB RS Power Boost levels for TC4.
TC4: RS
Boost=1.7dB
A2TTT=1280ms
11/6/2012
TC1: RS Boost=3dB
11/15/2012
TC2: RS Boost=1.7dB
12/4/2012
TC3: RS Boost=0dB
TC4: RS
Boost=1.7dB
A2TTT=1280ms
Observations:
1.
2.
3.
Increase in UL HARQ ACK for QPSK and16QAM after RS Boost change from 3dB to 1.7dB.
More improvement in UL HARQ ACK for QPSK and 16QAM after change from 1.7dB to 0dB.
UL HARQ success rate follows the RS Power Boost. Overall degradation due to the A2 time to trigger
increase.
11/6/2012
TC1: RS Boost=3dB
11/15/2012
TC2: RS Boost=1.7dB
Observations: Trending increase in ERAB events.
12/4/2012
TC3: RS Boost=0dB
TC4: RS
Boost=1.7dB
A2TTT=1280ms
11/6/2012
TC1: RS Boost=3dB
TC2: RS Boost=1.7dB
11/15/2012
12/4/2012
TC3: RS Boost=0dB
TC4: RS
Boost=1.7dB
A2TTT=1280ms
Observations: ERAB and RRC connections vary. Trending upward with normal traffic
growth.
Conclusions
• Increase Accessibility, Retainability, DL Throughput, DL/UL
HARQ ACK Rate of QPSK&16QAM after RS Boost change from
3dB to 1.7dB, and then those indicators were further improved
after change from 1.7dB to 0dB:
• Increase in Intra Handover Successful Rate the following
indicators after RS Boost change from 3dB to 1.7dB, while
those indicators shows no more increase after further change
from 1.7dB to 0dB
• IRAT Rate becomes higher and higher with decrease in RS
Boost value.
– A2 Time to Trigger lowered the IRAT rate but had an
adverse effect on throughput since UEs were held longer in
poor RF conditions.
THANK YOU

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