SINR QAM

1. Award Solutions Proprietary
DAS Impact
on LTE Network and UE
IBTUF VIII
Austin TX, Jan-2014
Nishank Save
Award Solutions
nsave@awardsolutions.com

2. Award Solutions Proprietary
Objective
• Understand the importance of macro
optimization for improving DAS
performance
• List the RF parameter considerations to
improve DAS performance
• Explain SINR mapping changes that can
improve throughput performance in DAS

3. Award Solutions Proprietary
Importance of
Macro Optimization

4. Award Solutions Proprietary
Importance of Macro Optimization
• Impact of Macro design on performance is
more in DAS than Macro
Macro design
• Lower the interference – better the throughput
Lower Macro RSRP
• A lower RSRP from a Macro can result in
significant cost savings
• Lesser number of remotes and antennas
required to overcome the Macro RSRP
Cost savings in DAS design
Throughput
Interference
Macro
RSRP
DAS Cost
$

5. Award Solutions Proprietary
Macro Optimization Challenges
• DAS design team needs information about Macro
Inputs about Macro
• A Macro was used to cover the venue before DAS deployment
• Venue is no longer the primary objective of that Macro
DAS cut-over - Macro optimization?
• Access to venues is easier for
implementation/ integration/
build out, but limited for walk
test and CW tests.
Walk Test and Drive Test data is scarce

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• DAS design team to work in close interaction with the
Macro design engineer for surrounding sites
Synergy
• DAS cutover plan should include macro optimization plan
– downtilts and azimuth changes
Cutover Plan
• Abundant walk test and drive test data should be
collected
• Changes may be needed in legal framework to provide
access to venues for walk test and CW tests.
Test Data
Optimization Considerations

7. Award Solutions Proprietary
Action Plan – DAS cutover
• Sector 1 – change azimuth from 120 deg to 100 deg
• Sector 2 – change downtilt from 6 deg to 8 deg
• Sector 3 – change A3 handover offset from 6 db to 2 db
Site 567971
• Sector 1 – add A5 measurement report
• Sector 3 – change antenna from 65 deg HBW to 35 deg HBW
Site 235697
• Reduce from 4 sector site to 3 sector site – deactivate sector 2
• Sector 1 – change azimuth from 40 deg to 70 deg
• Sector 3 – change downtilt from 6 deg to 4 deg
Site 629045

8. Award Solutions Proprietary
Handover in DAS
• Tightly controlled handovers reduce interference
Boundaries
• Well defined PCIs
• Tweak Remote Unit Tx power
Remote Unit
• Stairwells
• Seating area splits
Select natural boundaries

9. Award Solutions Proprietary
Cell Reselection/Handover Parameters
• Entry and exit points to venue
• Starts receiving signals from 2nd tier macros
• Customize cell reselection parameters
• Qrxlevmin / Qoffset / Qrxlevminoffset /
Qhyst / Qoffset
Walk test
RRC idle
mode
• Configure measurement reports A4 and A5
• Customize handover parameters
• Hys / Thresh / Ocn / Ocs / Off
Walk test
RRC
connected
mode

10. Award Solutions Proprietary
Measurement Event A5 on DAS
Thresh2
Thresh1
Neighbor cell
Time at which the
measurement report is
sent
Serving cell
Shall we increase Thresh1
to speed up handover?
Low throughput
High throughput

11. Award Solutions Proprietary
Measurement Event A4 on Macro
Shall we increase Thresh to
– slow down handover to DAS?
Thres
h
Neighbor
cell
RSRP/RSR
Q
Time at which the
measurement report is
sent
Event A4:
Neighbor becomes better than threshold
Low throughput
High throughput

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Design Parameter
Considerations for DAS

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Advertised vs. Actual Tx Power
• eNB announces EPRE in SIB2
EPRE
• 40W eNB (10MHz LTE): EPRE = 18dBm
• 40mW remote (10MHz LTE): EPRE = -
12dBm
• Difference = 30 dB
Example

14. Award Solutions Proprietary
SIB Parameter Changes for DAS
UE
overestimates
path loss
Target Initial
Received
PowerDAS =
Target Initial
Received
Powermacro ?
If Yes,
UE transmits
the RA
preamble at
higher power
(e.g., 30dB)
Optimize
Target Initial
Received
PowerDAS and
number of
preamble
retries

15. Award Solutions Proprietary
Tx Power Attenuation for DAS
Default eNB Tx Power = 40 W
DAS Headend input as low as 0 dBm
Attenuation in downlink using DAS
Tray
• Reverts to default value after a new download
• Damage to the DAS Headend
Parameters may be customized

16. Award Solutions Proprietary
PCI Planning
PCI = 254 (2, 14) PCI = 342 (0, 12)
Check for PCI mod 6 and PCI mod 30
conflicts
PCI = 402 (0, 12)
Confli
ct
No
Confli
ct

17. Award Solutions Proprietary
SINR and Throughput

18. Award Solutions Proprietary
RSRP and SINR
Adequate RSRP
+ Good SINR =
Good
Throughput
Good RSRP
+ Poor SINR =
Poor
Throughput
SINR is a better measure of potential performance than RSRP

19. Award Solutions Proprietary
CQI and SINR
CQI is estimated by
the UE based on
SINR of reference
signal from the
serving cell
DAS often have
higher pollution,
resulting in lower
CQI estimates
CQI-to-SINR mappings should be modified for
DAS

20. Award Solutions Proprietary
SINR Mapping Considerations
CQI Index Modulation
Typical SINR
mapping (in dB)
SINR mapping
consideration for
DAS (in dB)
0 Out of Range
1 – 6 QPSK -6.00 <SINR< 2.75 -4.00 <SINR< 5.00
7 - 9 16QAM 5.00 <SINR< 8.50 6.75 <SINR< 10.75
10 - 15 64QAM 10.75 <SINR 12.50 <SINR

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Questions?

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Thank You!