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COVERAGE VERIFICATION - Primary Common
Pilot Channel
Verify P-CPICH detection to minimize coverage holes
• P-CPICH RSCP
• P-CPICH Ec/No
Coverage level RSCP [dBm] Ec
/N0
[dB]
Sufficient RSCP ≥ −100 Ec
/N0
≥ −14
Poor −115 ≤ RSCP <−100 −16 ≤ Ec
/N0
< −14
No coverage RSCP < −115 Ec
/N0
<−16](https://image.slidesharecdn.com/da45f30f-ed00-4c24-9a02-5b7641224b7a-160626050837/75/08-DRIVE-TEST-Analysis-16-2048.jpg)
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INTERFERNECE
-100
-90
-80
-70
-60
-50
-40
-30
-25 -20 -15 -10 -5 0 5
Ec/Io [dB]
RSCP[dBm]
High interference
By correlating low Ec/No with high RSCP, areas with high
interference can be detected](https://image.slidesharecdn.com/da45f30f-ed00-4c24-9a02-5b7641224b7a-160626050837/75/08-DRIVE-TEST-Analysis-19-2048.jpg)
Uploaded byAmit vishwakarma
08. DRIVE TEST Analysis
This document provides information about MobileComm Technologies' drive test process for UMTS networks. It includes documentation on tools used for tuning and optimization, parameters measured, call flows, key performance indicators, examples of coverage and interference issues identified, and tips for network tuning. The document contains 47 slides covering topics like coverage verification using P-CPICH measurements, identifying interference and overshooting issues, analyzing call drops, tuning for voice and data calls, and comparing mechanical vs electrical antenna tilts.
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08. DRIVE TEST Analysis
- 1. MobileComm Technologies IndiaPvt. Ltd. Dallas . Atlanta .Washington .LA . Sao Paulo .New Delhi . Toronto .Muscat. Sydney Drive Test Process
- 2. 2 Copyright 2010 MobileCommTechnologies India Pvt. Ltd. All rights reserved MobileComm is committed to providing our customers with quality instructor led Telecommunications Training. This documentation is protected by copyright. No part of the contents of this documentation may be reproduced in any form, or by any means, without the prior written consent of MobileComm Technologies . Document Number: RK/CT/3/2010 This manual prepared by: MobileComm Technologies MobileComm Technologies(India)Pvt. Ltd. 424, First Floor, Udyog Vihar Phase -4, Gurgaon-122002 Headquarter: MobileComm Professionals Inc. 1255 West 15th Street, Suite 440 Plano, TX, 75075 Tel: (972) 633-5100 Fax: (972) 633-5106 www.mcpsinc.com
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- 4. 4 Soft/Softer Handover/Clear Call to aMS Paging Call from a MS RRC Connection RAB Assignment Supervision on PICH/ SCCPCH on FACH/ SCCPCH Predefined Signaling RAB Selected on FACH/ SCCPCH on DPDCH Assignment of DPDCH on RACH Activate Algorithms Power Ctrl. Code Ctrl. Admission Ctrl. RAB Selection MEASUREMENTS •Directed Retry •Load Sharing Soft Handover •Inter cell/BSC •Intra cell/BSC •OL/UL •Bad Quality •Urgency •HCS InnerLoop/OuterLoop PowerControl (RRC Connect. Perform.) (Random Access) (RAB Establish. Fail.) (Traffic Erlangs) (Call Quality) (Handover Perf.) (Dropped Calls) (Available TCH) (Paging Perf.) UMTS Call Flow Open Loop Power Control (Throughput) 4
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- 6. 6 • TEMS Investigationfor WCDMA (Software) • TEMS Scanner (Software + HW) • External GPS • User Equipment (UE) • TEMS DeskCat for post processing • MCOM3g/Mapinfo • MS Access/Excel based tools Tools For Tuning/Optimization & Data Post Processing Active measurement needed due to lack of statistics
- 7. 7 WINDOWS USED INWCDMA DRIVE TEST
- 8. 8 RADIO PARAMETERS WCDMABAR CHARTS
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- 11. 11 AMR CODEC USAGEIN WCDMA
- 12. 12 Notes on quantitiesdenoting signal power
- 13. 13 USB2USB1 Com 1 scanner Short callLong Call USB1 CS64 GPS USB1 PS Drive Test Equipments for Voice, CS64 & PS call Drive test tools configuration
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- 15. 15 The basic measurementsof scanner are • CPICH_RSCP (received signal code power) • CPICH_Ec/No (received energy per chip divided by the power density in the band) • RSSI (received signal strength indicator) What can you achieve with scanner? • Crossed feeder issues (DL) • Coverage verification • Interference problems (overshooting cell, pilot pollution) • Missing neighbours PILOT TUNING
- 16. 16 COVERAGE VERIFICATION -Primary Common Pilot Channel Verify P-CPICH detection to minimize coverage holes • P-CPICH RSCP • P-CPICH Ec/No Coverage level RSCP [dBm] Ec /N0 [dB] Sufficient RSCP ≥ −100 Ec /N0 ≥ −14 Poor −115 ≤ RSCP <−100 −16 ≤ Ec /N0 < −14 No coverage RSCP < −115 Ec /N0 <−16
- 17. 17 • Yellow isgood • Blue can generate problems • Grey is bad Best Server Signal Strength (RSCP)
- 18. 18 • Green isgood • Blue can generate problems • Orange is bad Pilot Ec/No Measurements
- 19. 19 INTERFERNECE -100 -90 -80 -70 -60 -50 -40 -30 -25 -20 -15-10 -5 0 5 Ec/Io [dB] RSCP[dBm] High interference By correlating low Ec/No with high RSCP, areas with high interference can be detected
- 20. 20 INTERFERENCE (RSCP >-90 dBm AND Ec/No < -9 dB)
- 21. 21 Primary Common PilotChannel (P-CPICH) – OVERSHOOTING
- 22. 22 OVERSHOOTING Change Proposal: Site-D,Sector-1, Antenna Down-tilt 8 Degrees
- 23. 23 Primary Common PilotChannel (P-CPICH) – PILOT POLLUTION • P-CPICH RSCP • P-CPICH Ec/No High CPICH reception levels from many Cells, (more than MAX_ACTIVE_SET) size serving cc ASthreshold N E N E countPilot >−≥ )( 00
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- 26. 26 PILOT POLLUTION Change Proposals Site Name Sector Number SCof Pilot Height of Antenna (meters) Antenna Tilts (degree) Proposed Antenna Tilts (degree) A 1 173 38 2 5 A 2 76 38 2 4 D 1 485 47.3 2 8 C 2 24 39.2 3 5 B 3 79 27 2 3
- 27. 27 0 5 10 15 20 25 30 35 Numbers of Samples 173 76485 79 24 SC of Pilots 0 5 10 15 20 25 30 35 40 Number of Samples 173 76 79 24 SC of Pilots PILOT POLLUTION Initial Drive Test (before tuning) Verification Drive Test (after tuning)
- 28. 28 UE TUNING • Voice/Video/PS calls – Long calls – short calls • Identify problem areas – Blocked calls – Dropped calls – Delay/Throughput
- 29. 29 Short Calls Analysis Set-upa call and maintain it for a pre-defined time duration (for 15-60 s) Call set-up failure and drops during short calls can be mainly used to analysis Accessibility failure due to: • UE Failure • Unsuitable Parameters Setting • Coverage Problem • Interference • Others
- 30. 30 Long Calls Analysis Dropsduring long call can be used to identify: • Missing Neighbor Relation • Coverage Problem • UE Problems • Network Characteristics • Best Parameter Setting • Others Set-up a call and maintain it until it is drop (used for the analysis of Retainability performace)
- 31. 31 KEY PERFORMANCE INDICATORS Accessability(Call set-up success rate) Retainability (Dropped calls) Mobility (Handover success rate) Integrity (BLER and throughput)
- 32. 32 Case 1: Dropdue to missing neighbor Problem: Detected Nighbor (DN) • UE sends a Measurement Report that contains an event1a means adding a new RL (cell) to Active Set • If the reported cell is not in the current neighbor cell list and the reported Ec/No is better than the best serving cell Ec/No in AS by some dBs (set by a RNC parameter) • If for any reason the new cell can not be added to AS, call will be released
- 33. 33 Case 1: Dropdue to missing neighbor “DN” cell better than the serving cell DL BLER gets worse “DN” cell better than the serving cell DL BLER gets worse
- 34. 34 Case 2: Dropdue to Poor Coverage (low RSCP) Problem: Poor DL coverage When UE gets to an area with low RSCP ( < -105 dBm) regardless Ec/No values there is high risk for drop. UE will likely ramp up the transmitted power and reach its max power. The DL BLER will probably increase and SIR target cannot maintain anymore, finally the call drops.
- 35. 35 Case 2: Dropdue to DL Poor Coverage Very bad RSCP UE max Tx power and high DL BLER Very bad RSCP UE max Tx power and high DL BLER
- 36. 36 Case 3: PS: SessionError due to Poor DL Coverage UE enters a very low coverage area (RSCP < – 105 dBm). The packet connection is carried on a 64/64 DCH Channel as consequence of the low coverage conditions. The UE will likely ramp up its power to the maximum, goes to Idle Mode and the Application and RLC throughputs go to zero. At this point the RAS application will start the Session Timeout timer, if the throughput is not resumed the Session Error event is triggered with cause “session timeout”.
- 37. 37 PS: Session Errordue to Poor DL Coverage App throughput ~64kbps Very low RSCP App throughput ~64kbps Very low RSCP
- 38. 38 FINAL WORDS • Fornetwork tuning, we need to relay on field measurements which require extensive drive tests • Finding the best possible configuration for antenna heights, tilts, azimuths and parameter setting for all the present cells/sectors in the network and also for any new sites that might be needed to improve coverage • Power adjustment can also be used for network tuning but can become complicated and result in poor network performance • Use of Remote Electrical Tilt (RET) Antenna is preferred over mechanical tilt antenna • Neighbour definition is of prime importance in UMTS network (Soft handover gain and interference reduction). Keep neighbour list upto 20. • Automated tools are needed that could suggest the best possible neighbour relations, antenna heights and tilts by using both the field measurements and the propagation models & simulations • Skilled people, right methods and advanced tools are needed to perform 3G tuning and optimisation
- 39. 39 Comparison of Mechanicaland Electrical Down-tilts
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- 41. 41 RRC messages information Voiceand Video are both Conversational Call
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- 43. 43 RRC messages information UEin DUAL MODE
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- 45. 45 RRC messages information CScall, 64Kbps, Transparent Video Call
- 46. 46 RRC messages information VideoCS 64: DL SF 32 UL SF 16 Voice AMR: DL SF 128 UL SF 64
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- 48. 48 WCDMA Coverage –Implications • High Pilot Signal Strength ¹ Guaranteed Coverage. • Coverage defined by Ec/I0. • Ec = RSCP – Received Signal Strength of own Pilot. Constant. • I0 = Interference from all other users , own cell + other cells. • Interference increses when traffic increases. • Cell coverage smaller when traffic increases. • Cell Breathes. • Target Ec/I0 = - 16 dB. • Ec/I0 below –16 dB => No channel estimation, No Coverage.