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

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

Importance of Macro Optimization

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 $

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

Optimization Considerations 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

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

Handover in DAS Tightly controlled handovers reduce interference 6 | Configuring DAS Tightly controlled handovers reduce interference Boundaries Well defined PCIs Tweak Remote Unit Tx power Remote Unit Stairwells Seating area splits Select natural boundaries

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 RRC connected mode

Measurement Event A5 on DAS Served by macro inside venue Served by DAS inside venue Shall we increase Thresh1 to speed up handover? High throughput Low throughput Thresh2 Thresh1 Neighbor cell Time at which the measurement report is sent Serving cell

Measurement Event A4 on Macro Served by macro Served by DAS Shall we increase Thresh to – slow down handover to DAS? High throughput Low throughput Thresh Neighbor cell RSRP/RSRQ Time at which the measurement report is sent Event A4: Neighbor becomes better than threshold

Design Parameter Considerations for DAS

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

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

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

Check for PCI mod 6 and PCI mod 30 conflicts PCI Planning PCI = 254 (2, 14) PCI = 342 (0, 12) PCI = 402 (0, 12) No Conflict Conflict Check for PCI mod 6 and PCI mod 30 conflicts

SINR and Throughput

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

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

SINR Mapping Considerations 4 | LTE Essentials for DAS CQI Index Modulation Typical SINR mapping (in dB) SINR mapping consideration for DAS (in dB) 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

Questions?

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