analysis and troubleshooting for cdma and cdma2000

MSS-RF-ER026CK Analysis and Troubleshooting for CDMAOne/CDMA2000 Issue 1.1

-LUCENT TECHNOLOGIES PROPRIETARY- 01/22/2003 Use pursuant to Company Instructions

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RF Engineering Services

Analysis and Troubleshooting for CDMAOne/CDMA2000

Layer E

January 22, 2003

As the undersigned OWNER I am responsible for keeping this document current:

Original Signature on File Date:

Tung Nguyen

As the undersigned AUTHOR of this document, I have reviewed it for conformance to the document template MSS-RF-QF001:

Original Signature on File

Date:

Minh Nguyen

This document is controlled electronically. Document users can verify current document version and/or obtain a copy of the document from the following web site:

http://globalrfmandp.wh.lucent.com



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Date:

Approved: Dai-Chieh Tsao AP WTCs Original Signature on File

Date:

Approved: Michael Whang Korea MSS


Date:

Approved: Javier Maysonet CaLA WTCs



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CHANGE RECORD This section provides a history of changes made to this document:

Date Reason for Change Issue # May 1, 2002 Initial Release from 602 Handbook sections 609,

629, 645, 660, 726, 727 and 729 1.0

January 22, 2003 Change reference number from MSS-RF-EP064 to MSS-RF-EP064CK and document title

1.1

END OF CHANGES



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TABLE OF CONTENTS

1 PURPOSE AND SCOPE...............................................................................................6

2 GENERAL ...................................................................................................................6 2.1 CDMA System Parameters........................................................................................6 2.1.1 First Pass Optimization Parameters........................................................................7 2.1.2 Second Pass Optimization Parameters ....................................................................7 2.1.3 Fixed Parameters...................................................................................................9 2.2 3G-1X Migration Scenarios ..................................................................................... 10 2.2.1 Scenario #1: Addition of 3G-1X on Existing 2G Carrier .......................................... 10 2.2.2 Scenario #2: Addition of 3G-1X on a New Carrier .................................................. 10 2.2.3 Scenario #3: Partial Network Addition of 3G-1X on Existing Carrier ........................ 10 2.2.4 Scenario #4: Partial Network Addition of 3G-1X on a New Carrier .......................... 11 2.3 Review of 3G High Speed Data ............................................................................... 11

3 SECTOR TESTING .................................................................................................... 11 3.1 Introduction ............................................................................................................ 11 3.2 Data Analysis.......................................................................................................... 12 3.2.1 Data Analysis for 2G Network ............................................................................... 12 3.2.2 Data Analysis for 3G Network ............................................................................... 13

4 UNLOADED COVERAGE TESTING ........................................................................... 14 4.1 Introduction ............................................................................................................ 14 4.2 Data Analysis.......................................................................................................... 14 4.2.1 Data Analysis for 2G Network ............................................................................... 14 4.2.2 Data Analysis for 3G Network ............................................................................... 17

5 LOADED COVERAGE TESTING ................................................................................ 19 5.1 Introduction ............................................................................................................ 19 5.2 Data Analysis.......................................................................................................... 20 5.2.1 Data Analysis for 2G Network ............................................................................... 20 5.2.2 Data Analysis for 3G Network ............................................................................... 24

6 SYSTEM-WIDE OPTIMIZATION TEST ........................................................................ 27 6.1 Introduction ............................................................................................................ 27 6.1.1 Data Analysis for 2G Network ............................................................................... 27 6.1.2 Data Analysis for 3G Network ............................................................................... 28

7 ORIGINATION AND TERMINATION TESTING ............................................................ 28 7.1 Introduction ............................................................................................................ 28 7.2 Data Analysis.......................................................................................................... 29 7.2.1 Data Analysis for 2G Network ............................................................................... 29 7.2.2 Data Analysis for 3G Network ............................................................................... 30

8 3G-1X INTER-FREQUENCY AND INTER-GENERATION HANDOFFS TESTING.......... 30 8.1 Introduction ............................................................................................................ 30 8.2 Data Analysis.......................................................................................................... 31 8.2.1 3G1X to 2G Same Frequency Handoffs (Inter-generation) ..................................... 31 8.2.2 3G1X to 2G Inter-frequency Handoffs (Inter-generation, Inter-frequency)................. 32 8.2.3 3G1X to 3G1X Inter-frequency Handoffs................................................................ 32



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9 COMMON CDMA OPTIMIZA TION TECHNIQUES........................................................ 32 9.1 No Service .............................................................................................................. 32 9.1.1 Inadequate Pilot Signal Strength from Serving Sector Forward Link ...................... 32 9.1.2 Paging or Access Channel Message Failure.......................................................... 33 9.2 Dropped Calls......................................................................................................... 34 9.2.1 Unrecognized Neighbor Sector Forward Link ...................................................... 34 9.2.2 Inadequate Search Window size Forward Link .................................................... 34 9.2.3 Inadequate Signal Strength Forward and Reverse Link ........................................ 35 9.2.4 Rapidly Rising Pilot Conditions Forward Link ...................................................... 35 9.2.5 Excessive Number of Pilots Forward Link ........................................................... 35 9.3 Poor Voice Quality.................................................................................................. 36 9.3.1 Inadequate Traffic Channel Signal Strength Forward Link .................................... 36 9.3.2 Inter-Modulation Interference Forward Link ......................................................... 36 9.3.3 Poor Voice Quality Reverse Link ........................................................................ 36

10 REFERENCES ........................................................................................................... 38 Figure 1: 3G-1X Migration Scenario 1 ................................................................................ 10 Figure 2: 3G-1X Migration Scenario 2 ................................................................................ 10 Figure 3: 3G-1X Migration Scenario 3 ................................................................................ 10 Figure 4: 3G-1X Migration Scenario 4 ................................................................................ 11



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1 Purpose and Scope The most significant objectives of the optimization testing for both CDMA 2G and 3G (also known as CDMA2000) are the following: first, to ensure that acceptable coverage is achieved for the pilot, paging, synchronization, access, and traffic channels; second, to minimize the number of dropped calls, missed pages, and failed access attempts; third, to control the overall percentages of 1, 2, and 3-way soft/softer handoff; and fourth, to provide reliable hard handoffs for CDMA-to-AMPS or CDMA f1-to-f2. The purpose of this document is to help the RF optimization engineers achieving those goals by providing the method in analyzing the drive test data collected during the testing period. Some typical problems encountered most frequently during the optimization and the remedies for each problem are also presented. The document only covers the problems due to fundamental CDMA problems or problems with the Lucent Technologies CDMA implementation. Software bugs and quirks relevant to a particular software release are not discussed. It is assumed that all RF related translations have been inspected and set at the correct values before any tests to be conducted1. For 2G networks, we will focus on the analysis involved in the optimization steps of a new single carrier network deployment and adding an additional carrier on the existing system. In the case of adding a new carrier, we usually use live traffic as load and conduct the tests during the maintenance window. Therefore, there will be no unloaded coverage test. We assume all carriers of the existing system should be fully optimized before attempting to optimize an additional carrier. If otherwise stated, the general analysis procedures for a 2G system are applied to both cases. With regard to 3G optimization, the document only intends to include the analysis and troubleshooting techniques related to 3G-1X for voice and 3G-1X combined voice/High Speed Data on a cold start (brand new) 3G network or a migration from 2G networks2. Throughout the document, the following convention will be used for 3G-1X terminology: Data: 3G-1X High Speed Packet Data (HSPD) service 3GV: 3G-1X Voice service 3GD: 3G-1X HSPD service 3G*: 3G-1X Voice or Combined 3G-1X Voice/Data service 2G: IS-95/CDMA One

2 General

2.1 CDMA System Parameters The translation database for the CDMA system contains a great number of parameters which impact the RF performance of the network. Many of these parameters have complex interactions involving system-wide influences upon capacity, coverage, and quality. For this reason, the main

1 Please refer to the document MSS-RF-EP097CK Verifying Translation Data for CDMA and CDMA2000 for more information. 2 Much of the contents of this document related to 3G1X optimization procedures came from [12] and [13]



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CDMA parameters have been divided into three categories: first pass, second pass, and fixed parameters. First pass optimization parameters are the primary tuning knobs which can be used to optimize the CDMA performance. Second pass optimization parameters should be changed in unusual cases where problems cannot be resolved during the first pass optimization. Fixed parameters should not be changed under any circumstances during the field optimization process. Most of the 3G-1X RF optimization parameters are shared with 2G. There are additional RF translation parameters provisioned to accommodate 3G-1X voice and data. The following sections categorize the CDMA parameters. The references [1-4] listed after each translation parameter referred to the application notes that provide detailed techniques for selecting appropriate values, parameter interactions, range limitations, and default settings.

2.1.1 First Pass Optimization Parameters The following CDMA system parameters should be used as the primary tuning controls for the RF optimization procedure during the first pass at optimization: 1. Neighbor list entries and associated priorities [4] 2. BCR/CBR attenuation (total forward link transmit power) [2] 3. Changes to antenna configurations (azimuth orientation, antenna height, downtilt angle,

antenna type) 4. Hard handoff and semi-soft handoff thresholds (CDMA-to-AMPS or CDMA f1-to-f2) [4] The first pass optimization parameters are the primary translations to be used to fix coverage deficiencies. Cell site transmit powers can be adjusted with BCR/CBR attenuation to address coverage spillover, overshoot problems, and multiple pilot coverage regions. In some cases, transmit powers can be adjusted to provide fill-in coverage for weak signal strength areas. Additional alternatives, such as antenna azimuth, downtilting or changing antenna patterns, can be used in problem cases where transmit power adjustments are insufficient to resolve a deficiency. During adjustment of BCR/CBR attenuation, care must be taken to assure that the forward and reverse links are approximately in balance (i.e. the tolerable path loss link margin is the same for uplink and downlink). The optimization of neighbor lists will be less of a problem during cluster tests, where only a small number of cells are active, than with system-wide tests, where many more sectors are simultaneously active. Due to the limited neighbor list size for each sector, tradeoffs are required to select entries which minimize dropped calls because of missed handoffs or handoff sequencing problems. CDMA semi-soft handoff and hard handoff thresholds (from F2 to F1, F1 to F1, including 2G to 2G, 3G to 3G and 3G to 2G) will be discussed in the document.

2.1.2 Second Pass Optimization Parameters The following CDMA system parameters should only be changed to correct performance problems at specific trouble spots for further fine-tuning: 1. Soft handoff thresholds [4]



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2. Active set and cell site set search window sizes [5] 3. Access channel nominal and initial power settings [5] 4. Sector size and Access preamble size [5] 5. Digital gain settings for pilot, page, and sync channels [2] 6. Forward link traffic channel power settings [3] 7. RF load weighting factor [5][11] 8. Anchor hysteresis threshold [4] 9. Load preference delta [5] The second pass optimization parameters can have system-wide performance impacts, and therefore should be adjusted with caution, in cases were the adjusted parameters do not fully resolve a problem. For example, even small changes in soft handoff thresholds can impact overall system capacity and channel element utilization. In general, attempts should be made to keep a consistent set of handoff thresholds for the entire CDMA network. It is not advisable or practical to alter soft handoff thresholds on a sector-by-sector basis, particularly since handoff thresholds are determined by the primary cell in a multiway handoff; however, in local areas handoff parameters for a group of sectors covering a region can be changed to reflect small-scale differences. Search window sizes for the active and neighbor sets should be set initially based on expected cell sizes and multipath propagation delay spreads, as discussed in [5]. If the CDMA deployment contains a mixture of small cells and large cells, then window sizes may have to be adjusted on a case-by-case basis to accommodate all handoff scenarios. For example, if there is a large variation in the antenna heights for CDMA cells in the network, situations may occur where the mobile enters soft handoff with a distant cell. If the mobile uses the distant base station to obtain a timing reference, then the mobiles reference clock will be retarded by the large propagation delay between the mobile and the distant cell site. When scanning for neighbor list pilots, the mobile will center its search window around the expected time delay of the neighbors pilot PN offset, as calculated based on the mobiles reference timing. Since the mobiles reference time is retarded by the propagation delay from the distant cell to the mobile, the location of the search window will be skewed by the propagation delay time. In such a situation, if the search window size is not large enough, the mobile may fail to detect pilots from close-in neighbors due to the retarded timing reference.

Access channel is the channel used by a CDMA mobile to originate a call and to respond to a page. The nominal transmit power offset (nom_pwr) and the initial power offset for access (init_pwr) in the ceqface form are the 2 basic translation parameters that impact the initial access probe power. The initial access probe power should be set high enough such that the first access probe can be detected at the cell with high probability. On the other hand, usage of excessive initial access probe power does not improve the access success rate, but instead creates strong interference to existing traffic users.

The sector size is used to calculate the access search window width. The access search window width should be large enough to ensure that all possible path delays in the coverage areas are included in the path delay hypotheses tests. The access preamble is a series of known symbols transmitted in the beginning portion of each access probe to assist the cell in detecting a mobiles signal through the whole range of delay hypotheses tests. Therefore, the access preamble size must be greater than the time that the cell needs to do all the hypotheses tests in the access search window. When a mobile originates a call on a multi-carrier cell, the base station will assign a traffic channel element on a specific carrier based on the traffic channel assignment (TCA) algorithm



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tca_alg. There are three options available for TCA algorithm: lowest RF loading (rf), origination carrier (oc), and lowest CCC loading (cc). The most commonly used option is rf. During the origination, the originating carrier is favored unless its loading exceeds that of the other carriers by the RF loading weight factor (tca_weight). These parameters are specified in the ecp and ceqface forms.

There are new parameters introduced in release 17.03 to address the need to distribute the load in systems with mix 2G and 3G-1X equipments. When a 3G-1X mobile initiates a call, it will be assigned a traffic channel that favors a 3G-capable carrier by 3G-1X Load Preference Delta. The same mechanism is applied to a 2G mobile using the 2G Load Preference Delta parameter. Both parameters are located in the ceqface3g form. The parameter Allow Sharing 3G1X Carrier in the ceqface3g form allows 2G mobiles to access a 3G-1X carrier.

In general, these parameters must be set for the entire area because only the values of the primary sector are sent to the mobile, except for the case of IS95B soft handoff parameters. When the soft handoff and search window enhancement feature (FID 3608.0) is activated at any leg in the active legs, the selection algorithm will be enabled for optimal selection of the new IS95B soft handoff parameters from among the active legs that have IS95B soft handoff feature enabled. To ensure that the correct values are sent, all possible primary sectors must have the reserved parameters set the same.

2.1.3 Fixed Parameters The following CDMA system parameters should not be adjusted during the RF optimization procedure: 1. Forward and reverse power control thresholds 2. Remaining set search window size 3. Forward and reverse overload control set points 4. Minimum, maximum, and nominal traffic channel digital gains 5. Reverse pilot to FCH (Fundamental channel) offset 6. Anchor monitoring interval 7. Forward and reverse supplemental allocation parameters 8. Forward and reverse power control thresholds for data SCH The fixed parameters involve quantities that should not be adjusted during field optimization. These include the power control thresholds, the overload control set points, and some search window sizes. Since power control plays such a critical role in both reverse link and forward link performance for the CDMA system, related thresholds and step sizes should only be adjusted based on simulations or lab measurements. For the optimization tests it is recommended that reverse overload control thresholds be set to their maximum values allowed in the translations to avoid false alarms during the loaded drive testing. Due to the forward overload control algorithms role as the sole overdrive protection mechanism for the linear power amplifier, the forward overload control parameters should be adjusted based on lab tests and computer simulations.



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2.2 3G-1X Migration Scenarios There are several possible 3G-1X deployment scenarios that involve migration from 2G network as described in the following sections and each scenario requires a different optimization procedure. We will refer to these scenarios wherever 3G is mentioned in the rest of the document. For simplicity, the scenarios are depicted with 2 carriers only, but it is easy to expand the case to more than 2 carriers.

2.2.1 Scenario #1: Addition of 3G-1X on Existing 2G Carrier

Figure 1: 3G-1X Migration Scenario 1

In this scenario, the customer deploys 3G-1X on one or more existing carriers throughout the network to provide ubiquitous 3G* coverage.

2.2.2 Scenario #2: Addition of 3G-1X on a New Carrier


In this scenario, the customer deploys the 3G-1X service on a brand new carrier throughout the network.

2.2.3 Scenario #3: Partial Network Addition of 3G-1X on Existing Carrier


F1: 2G F2: 2G

F1: 2G F2: 2G

F1: 2G F2: 2G/3G*

F1: 2G F2: 2G

F1: 2G F2: 2G F3: 3G*

F1: 2G F2: 2G

F1: 2G F2: 2G/3G*



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In this scenario the customer deploys the 3G-1X service on an existing 2G carrier only in a portion of the network

2.2.4 Scenario #4: Partial Network Addition of 3G-1X on a New Carrier

Figure 4: 3G-1X Migration Scenario 4 This scenario is a combination of the scenarios 2 and 3. This case applies to customers deploying 3G-1X on a new carrier but only in a portion of the entire network.

2.3 Review of 3G High Speed Data Optimization of a 3G Voice/Data network shares most of the goals mentioned earlier in the introduction. However, the introduction of data requires additional considerations relative to a voice only network. It is important to minimize forward pilot overlap and providing acceptable data throughput in the desired coverage area. On the forward link, high-speed data of up to 153.6 Kbps can be transmitted on the Forward-Supplemental channel (F-SCH). The call is always in simplex mode (no handoff allowed) and the cell/sector that carries the high-speed data call on F-SCH is called the anchor cell/sector. If a pilot reported by the pilot is anchor-capable and its signal strength is greater than or equal to that of the anchor cell by Anchor Hysteresis, the cell will perform Anchor Transfer. The current anchor cell will be released; the F-SCH will be torn down. The new pilot will then be declared as the new anchor cell and the F-SCH may be setup again. In order to achieve good throughputs on the forward link, it is desirable to minimize interference to the anchor pilot from the other fundamental channel (FCH) Active Set Pilots as well as minimize the SCH interruptions stemming from frequent anchor transfers. To meet these objectives, it is very important to create dominant pilot regions. Care should be taken while doing so to improve data performance since the changes could adversely impact the performance of the 3G Voice. Unlike the simplex F-SCH operation, soft/softer handoffs (up to 4 legs) are supported on the Reverse-Supplemental Channel (R-SCH).

3 Sector Testing

3.1 Introduction The primary purpose of a sector testing is to verify the antenna radiation pattern and detect any hardware, software, and translation errors for each cell site. Horizontal antenna aiming is the major concern at this point, NOT the RF coverage. The sparse drive route data and the unknown

F1: 2G F2: 2G

F1: 2G F2: 2G

F1: 2G F2: 2G F3: 3G*



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state of the neighboring cells preclude making changes in parameters or vertical tilt based on the results of this test.

3.2 Data Analysis

3.2.1 Data Analysis for 2G Network

3.2.1.1 Single Carrier Systems

The Ec/Io is plotted on a separate sheet for each PN offset and labeled with the sector name and true direction. For instance, if the beta antenna was aimed 255, it would be labeled beta=255. On each plot, a pie slice should be drawn representing the desired direction of coverage. The Ec/Io of a particular PN offset should be strongest within the pie slice. Unfortunately, the analysis is not as easy as it sounds. There are several factors other than antenna orientation that affect the plots. Below are some examples:

1. The drive route may run at an angle to the cell rather than on an arc around it. This will cause the points further from the cell to be weaker even when they are within the beam of the antenna. Close points may be strong even if they are not in the main beam of the antenna.

2. Terrain or buildings can cause the signal to be weaker in some areas

3. Signals present from other cells will cause Ec/Io to decrease. If the neighbors on one

side of the cell are turned on while the neighbors on the other side are not integrated yet, it will cause the Ec/Io values on the side with the radiating neighbors to be lower than expected. This can be detected by looking at the plot of Mobile Receive Power and Ec/Io Max Finger. If the Ec/Io of the individual PN offset is low but the Max Finger Ec/Io or Mobile Receive Power at that location, the cause may be the presence of another signal, not necessarily antenna orientation.

The most common problem encountered during the sector testing is incorrect antenna connections at the cell site. The transmitter of a specific sector is connected to the wrong antenna. In this case, the error is obvious when comparing the antenna orientations of the PN offsets on the Ec/Io plots. The remedial action is to inform the installation team to check the connections and swap the cables to the correct order. If the Ec/Io of a sector is very weak, the problem could be from antenna, cable, connector, or low output power due to poor calibration. Installation team also will be noticed to investigate all of these possible causes. The ECP ROP could be checked to see if there were any alarms. If there were dropped calls when driving between sectors it is possible that one of the antennas is not properly aimed. It is also possible that the drop was in an area that will be adequately covered when more cells are turned up. The temptation to start optimizing with sector drive data should be avoided. Decisions are better made when all the neighbor cells are integrated and the drive routes are more thorough.



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3.2.1.2 Multi-Carrier Systems If the new carrier is using an antenna which already has a transmit signal on it, a sector test is not required. The call through and CRTU function tests (Overhead, Traffic, Pilot Level and Antenna) ensure the new carrier is transmitting on the correct face and at a pilot level that is within the expected range. The plots of Ec/Io for each PN offset on both the common carrier and the new carrier must be generated using LDAT. Other plots such as Mobile Receive Power, Mobile Transmit Power and Forward FER may also be generated to give additional information if the Ec/Io plots show a problem between the two carriers. Compare the plots of the new carrier to the common carrier. The coverage will not match as there is likely much more interference on the common carrier than the new carrier. However, the coverage for each sector should be similar for the two carriers. Areas close to the cell that differ more than 3 or 4 dB or areas where the common carriers coverage is much stronger than the new carrier may indicate a problem. If the original sector plots of the common carrier are also being used for comparison, the coverage of the new carrier to the original sector plot of the common carrier should be very close. This is because the interference is essentially the same for these two plots. If there is a suspected problem, the other plots could be used to point out if it is a cell problem or antenna problem. The problems can be solved similarly to the case of a single carrier system.


3.2.2.1 3G Voice Deployment In the scenarios 1 and 3, since the 3G-1X service is applied on an existing 2G carrier, antennae are shared between the 2 networks, there is no need for sector testing. For the scenarios 2 and 4, sector testing has to be performed if new antennas are installed for the new 3G carriers. It is recommended that a 2G and a 3G-1X full rate Markov calls be placed on F2 and F3, res pectively, during the sector test. The analysis process is similar to that of 2G as specified in 3.2.1, with 1 additional task. The Ec/Io sector plots of the new carrier (F3) and the common carrier (F2) should be compared for each PN. The goal is to have the coverage for F2 and F3 comparable. At the edge of the cell, the coverage of F3 can be better than that of F2 due to less interference from the surrounding cells.

3.2.2.2 3G Combined Voice/Data Deployment No sector testing for scenarios 1 and 3 is required. For scenarios 2 and 4, since both 3G-1X Voice and HSPD services are provided on an additional carrier, both Voice and Data need to be optimized. Besides the 2 full rate Markov calls on F2 and F3, respectively, a 3G-1X HSPD call has to be setup on F3. Under the unloaded conditions, HSPD call should be assigned SCH (Supplemental Channel) rates of at least 8x. The analysis for voice will be similar to that of 3G Voice in 3.2.2.1



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4 Unloaded Coverage Testing

4.1 Introduction The objective of the Unloaded Coverage Test is to measure the forward channel pilot coverage and monitor the reverse link performance for unloaded conditions, with all sectors in the cluster transmitting pilot, page, and sync channels. No other CDMA traffic should be on the test cluster other than the test phones. Some translation parameters can be adjusted in order to improve the coverage, fix the neighbor lists and fine tune performance in the local areas. They include the Primary and Secondary parameters as specified in Sector 2.1.

4.2 Data Analysis

4.2.1 Data Analysis for 2G Network Using LDAT to post-process the drive test data, the following metrics should be plotted:

Max Finger Ec/Io, Dominant Pilot Ec/Io, Aggregate Pilot Ec/Io Forward Frame Error Rate (FFER) Reverse Frame Error Rate (RFER) Number of pilots above threshold Mobile Receive Power Mobile Transmit Power Alerts overlaid on Max Finger Ec/Io

The following steps illustrate what the analysis engineer should be doing with data as it becomes available during optimization.

1. Review Hardware Status

The analysis engineer should always be aware of the hardware issue within the cluster. This information should be readily available and kept up to date every day. Some examples are:

Cells with RFTG/GPS problems may present handoff problems and coverage problems

Cells with BBA/CCC problems may present complete coverage holes and the

absence of handoffs

Cells with packet pipe problems may look fine for coverage but not support proper handoffs or call setups

Look for asserts of HEH messages on the ROP at the time of the failures. These may indicate a hardware failure or software state problem that manifests itself as a dropped call.



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2. Review Pilot Coverage This data should be viewed on a per sector basis to determine the coverage area of each specific PN offset. Coverage holes that coincide with known cell problems need no further investigation. Analysis is required for holes with unknown causes. 3. Review Frame Error Rate This data should indicate any areas of the system where voice quality is less than desirable. Optimization should focus on areas where Forward Frame Error Rate (FFER) is over 5%. Any such areas identified should be noted. Usually, high FER is an indication of a weak or completely destroyed RF link. The cause could be a potential lack of coverage on the forward link or/and the reverse link. For RF coverage related problems see section 9.3. High FER and dropped calls usually share the same cause. Therefore, the same solutions offered in section 9.2 for dropped calls can be applied for high FER. Non-Coverage Induced Frame Errors:

Inspect the NPAR file for the Markov call. This will indicate the type of frame errors involved. If the bad frames are labeled as Erasures, then go to the next step. If the frames are labeled as 1800 Pri (eighth rate frames), or Bit Errors, then there is a software anomally causing problems with the Markov call. This is not indicative of an RF problem and will likely require a remove and restore of the ECUs involved in the call

If the frame errors immediately precede a dropped call, the dropped callis

probably the cause of the errors. This is usually the result of improper messaging between the mobile and the base station. See step 6 Investigate Dropped Calls for troubleshooting dropped calls

If the cell transmit and/or mobile transmit powers are unusually high while the other coverage indicators may still look good, it may be that some external interference or other source of unwanted RF energy is forcing power control to allocate more energy on one of the links. For this case, the spectrum should be monitored for interference, and the hardware should be inspected

Consider opening the neighbor and/or the remaining search window. If all else

fails, there may be additional CDMA signals the mobile is simply no identifying. If additional data collection does not show new pilots in the area, then the search windows should be returned to the initial values. This is an issue in area where many signals tend to propagate such as bridges, elevated highways, waterways, etc.

4. Review Neighbor List Alerts (NLAs) Using the outputs from the LDAT program3 (the ALERT text file and the plot of all alerts overlaid on Ec/Io plot), the analysis engineer should verify that neighbor lists are correct on all the routes.

3 Please see document MSS-RF-ER052 Data Processing Using LDAT and Other Tools for use of LDAT, Alert



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For each Neighbor List Alert (NLA):

Verify the pilot in question is appropriate to serve the area. If the signal strength is not very strong (less than 12 dB) then reducing the presence of the pilot rather than including it in the neighbor list is probably the best tactic. In this case, it is not a logical neighbor. Also, keep in mind that the cell coverage will shrink when the system is loaded. Under the loaded condition, this pilot might not be present in this area anymore. This can be confirmed after the loaded coverage test. If the pilot strength is a very strong overshoot from a far away sector, the pilot should be removed by increasing the BCR/CBR of that particular sector. Antenna downtilt should be considered if more than 4dB of BCR attenuation has to be added.

If the pilot is strong and indeed proper for the area, then it should be added to the

neighbor list. Remember to keep the neighbor list reciprocal. The removal of all NLAs is desirable. 5. Review Weak Pilot Alerts (WPAs) The ALERT text file will also indicate the areas where the strongest serving pilot is weaker than a particular threshold. The threshold is usually set to 12 dB initially. During the beginning stages of optimization, major problems in the cluster are detected and the number of alerts is kept to a manageable amount. WPAs should be reviewed as followed:

Verify the mobile is on the strongest available pilot. If another pilot is available at stronger signal strength, then it should be in the Active Set. If many WPAs are seen in the row with a stronger pilot present (but not in the Active Set) then the event should be investigated to determine why a handoff did not occur.

For areas that clearly appear to have weak coverage, the contributing sectors should

be evaluated to for potential increases in power (decreased attenuation). This should be done with care. Additional power that helps one location can adversely affect another.

For weak pilot areas where many pilots are present (4 or more), efforts should be

made to create some pilot dominance by either removing the pilots that least belong to the area or increasing the transmitted power of the pilots that are supposed to cover the area. This can be achieved with changing the BCR/CBR attenuations of the appropriate sectors. If changing BCR/CBR does not help, a new site might be the only way to go.

Note: Not all WPAs need to be removed. Some areas of weak coverage are unavoidable, and therefore, the alerts are acceptable.

6. Investigate Dropped Calls The ALERT text file indicates the times of dropped calls and the plot of dropped calls overlaid on Max Finger Ec/Io shows the locations of the drops.



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It would be helpful to obtain a coverage map from the design engineer so that we can identify the coverage holes in the network beforehand. Dropped calls that happen in the known problem areas should not be concerned. If the dropped calls happened in an area with strong Max Finger Ec/Io and weak mobile received power (less than 85dBm), it is possible that the mobile is at the edge of the coverage, with less interference and far from the sites. If the Max Finger Ec/Io is weak while the mobile received power is strong, the problem could be from interference (pilot pollution or local interference). In the other case, if both Max Finger Ec/Io and mobile received power are weak, there is a strong likelihood that a coverage hole exists. Actions to be taken when investigating these dropped calls are described in 9.2.

7. Investigate Neighbor Set Search Window Size The ALERT text file also give recommendation to increase Neighbor Set search window where needed. It is very important to set the Neighbor Set search window large enough so that the mobile can detect a strong neighbor pilot early enough for handoff. If the pilot at the edge of the Neighbor Set search window is strong (greater than 12 dB), it is advisable to increase the Neighbor Set search window to the recommended value. Please see also section 9.2.2 for additional information on Active Set search window. 8. The maps of handoff activity, obtained from mobile data, can be useful for setting handoff

thresholds, refining neighbor lists, and identifying trouble spots. 9. Make Translations/Hardware Changes and Recollect Once the entire route has been analyzed; problems understood and recommended changes implemented, the routes should be re-driven This process is repeated until no more progress is being made. The unloaded testing is complete when all of the routes in a cluster have minimized NLAs and WPAs, fixed or understood the dropped calls, and the general performance of the cluster is good. Unloaded testing is the time to fix the easy problems. Remaining problems can be fixed during loaded testing while the system is being further refined.


4.2.2.1 3G Voice Deployment

4.2.2.1.1 Cold Start 3G System The same metrics that are mentioned above for 2G also need to be plotted for 3G Voice only network using LDAT 3G.



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The data analysis steps for a cold start 3G Voice is also similar to those of 2G as described in section 3.2.1. 4.2.2.1.2 3G Migration Scenarios For the four 3G-1X migration scenarios, all the testing is performed under actual user load during regular hours or using OCNS load during the maintenance window due to the fact that the 2G carriers are already optimized. There will be no unloaded testing.

4.2.2.2 3G Combined Voice/Data Deployment 4.2.2.2.1 Cold Start 3G System In order to optimize a 3G Voice/Data capable carrier, a 3G full rate Markov call and a 3G data call are set up on the 3G carrier, during the drive test. Besides the metrics that are mentioned above, additional metrics need to be collected and analyzed such as:

Diff Ec/Io metric: difference between aggregate active set pilot Ec/Io and Max Finger Ec/Io computed from searcher energy (collected from Markov call)

Forward link FSCH FER per FSCH rate Forward link composite FER: Computed after weighting for each SCH rate (19.2, 38.4,

76.8, 153,6 kbps) and FCH rate (9.6kbps) Mobile Transmit Power (for reverse SCH channel) SCH Data Rate assigned (both fwd and rev links) Forward and Reverse Link RLP layer Throughputs Forward Link physical layer throughput (LDAT3G 1.3)

Data analysis efforts for the Markov call remain the same as in the case of 2G networks. For the data call, it is important to ensure dominant coverage with few pilots where possible. The focus should be on locating and fixing wide problem areas not local spots. Correlating several LDAT 3G metrics from both the full rate Markov call and the data call can help isolate the potential problem areas. Problem areas are the areas with:

Anchor pilot pollution index greater than 3dB Number of pilots above threshold greater than 3 Assigned F-SCH rate 4x or less in a region under unloaded conditions F-SCH FER greater than target F-SCH FER levels per assigned rate Forward link RLP throughput less than 70kbps for TTCP application under unloaded

conditions

The problem areas should be rank ordered based on the extent and severity as identified by several of the above metrics. The next step is to identify the underlying source of the problem areas. The most common reason for data performance degradation will be non-dominant pilot coverage . Note that often this happens in areas with low signal strength. As a general guideline, attempt to focus on problem areas that have sufficient signal strength (Mobile receive power is greater than 90 dBm) and avoid to fix the softer handoff areas.

If poor throughput is accompanied by poor performance on both F-FCH and F-SCH channels, such as high FFER, or dropped call, then this is likely to be a general performance issue (e.g. coverage problem, pilot overshoot, neighbor list omission, inadequate search window size, etc.). Such a problem should be fixed as outlined in Section 4.2.1. When troubleshooting data related



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problems, it is important to ascertain that these are not derived from network related congestion. Using a local server at the IWF for data transfer minimizes such concerns.

In the area with more than 3 pilot signals consistently observed, attempts can be made to provide dominant coverage by one or more sectors. The first step is to reduce the signal strength of the weakest sector by increasing the BCR/CBR attenuations in steps of 2dB. Re-drive the problem area after each adjustment and check for FER quality and handoff performance. If decreasing the weakest pilot signals by 4dB from the initial setting does not resolve the problem, attempts can be made to increase the levels of the strongest pilots by decreasing the BCR/CBR attenuations 2dB. Re-drive the area to check for performance. In some cases, it is preferable to adjust antenna (downtilt, higher gain antenna, etc.) since excessive BCR/CBR changes could create the imbalance issue between the forward link and the reverse link.

It is important to verify the reverse link performance after dominant pilot coverage is achieved on the forward link. As stated above, the reverse link support soft/softer handoffs on both R-SCH and R-FCH. The handoffs are beneficial to the reverse link coverage/capacity. When the system is loaded, the cell coverage will shrink and as the result, the soft handoff overlap will be reduced. Therefore, it is advisable to create good coverage area with 2 dominant pilots in the regions that already have more than 3 visible pilots.

Anchor transfer also impacts the data throughput due to the time taken to set up a new anchor. Anchor Hysteresis threshold might be increased to avoid unnecessary anchor transfers in some areas characterized by rapidly changing pilots. However, a too high Anchor Hysteresis threshold results in SCH transmission not on the strongest pilot and hence, affects the data performance. Use of Anchor Hysteresis threshold to improve anchor transfer is advisable only sparingly.

4.2.2.2.2 3G Migration Scenarios For the four 3G-1X migration scenarios, all the testing is performed under actual user load during regular hours or using OCNS load during the maintenance window due to the fact that the 2G carriers are already optimized. There will be no unloaded testing.

5 Loaded Coverage Testing

5.1 Introduction

The objective of the Loaded Coverage Test is to measure the performance of the CDMA system with actual or simulated loading conditions. During the testing, traffic can be simulated using OCNS (Orthogonal Channel Noise Simulator) [6] on the forward link and attenuation on the reverse link. For these tests, data are collected over the same drive routes used for the Unloaded Pilot Channel Coverage Survey Test. During the cluster testing, the objective is to identify, categorize, and catalog the coverage problems observed during the drive testing. Any coverage problems which cannot be solved with basic parameter changes, requiring less than 30 minutes of work, will be deferred until the system-wide optimization phase. Parameter adjustments during the cluster testing will be limited to the first pass and second pass parameters listed in Section 2.1.1.



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5.2 Data Analysis


5.2.1.1 Single Carrier Systems

All procedures in Section 4.2.1 for unloaded coverage testing are applicable to optimizing under load. The list below highlights the differences:

1. Suspect interference from friendly users During this phase of testing the system is artificially loaded to full capacity. Any additional calls will cause a dramatic drop in performance. Even having phones turned on in the area can cause problems due to their access probes. If the phones are denied service via country code changes, the problem may worsen. Those phones will ramp up to full power on their access probes. Overload classes should be used to grant service only to the test phones.

2. Review pilot coverage The pilot coverage under load will be worse than before. Any areas that had poor coverage during unloaded test should be targeted for review. In particular, they may require additional power to operate well under load. 3. Review Frame Error Rate (FER) It is expected that FER will also be worse under load. This is true for both the forward and reverse link. Any extended areas of FER degradation are candidates for additional work. Any high FER areas that still remain should be investigated for root cause 4. Review Neighbor List Alerts (NLA) There should be minimum number of NLAs under load. Any that shows up need to be scrutinized. 5. Review Weak Pilot Alerts (WPA) It is expected that WPAs will increase under load. They should be used to identify the areas of potential risk. Ec/Io can drop as much as 4dB. 6. Investigate Dropped Calls As in the unloaded case, each of these should be investigated 7. Identify and Reduce Multiple Pilot Areas Loading should reduce the number of multiple pilot areas. Any increase needs to be investigated and fixed 8. Make Translation/Hardware Changes and Re-Collect



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5.2.1.2 Multi-Carrier Systems

This document assumes the new carrier has been added as one or more contiguous clusters overlaying an existing carrier or carriers. In most cases, the existing carrier(s) will extend beyond the coverage area of the new carrier. In this case, it must be ensured that handoffs from the new carrier to the existing carriers occur at the border of the new carrier. If there is no CDMA coverage beyond a border cell in a cellular market, CDMA to Analog handoffs need to be examined for the new carrier.

Note: In this document, the term Fn is used to designate the new carrier and the term Fi is for the existing carrier.

There are two distinct steps when analyzing the performance of an additional carrier: 1. Core area analysis The core analysis consists of comparing all the plots from LDAT of drive route data for discrepancies. These discrepancies are then investigated and fixed. Both carriers should be investigated because problems with the existing carrier may be uncovered. The following section lists possible causes for discrepancies and their remedies. The goal of core area optimization is to match coverage. This is important since access may be on a different carrier than the carrier used for the traffic channel (cross-carrier traffic channel assignment). Anywhere coverage is good enough for access on one channel, it must be good enough to handle traffic on the other channel. Another reason is to ensure the same level of quality for users on any channel, and prevent forced handoff failures due to limited resources.

Note: When matching coverage, it is not always the carrier with the worst Ec/Io that is at fault. A very strong signal, where it is not expected, can also be the problem

In single carrier systems, the transmit and diversity 0 antennas are usually shared. With two carrier systems, the diversity 1 antenna is usually shared with the second carriers transmitter. In more than 3 carrier systems, additional transmit antennas may be used. However, all carriers share the two diversity receive antennas. Any antenna or cable problems will show up as forward path problem, that is, cell transmit and mobile receive. When there are discrepancies between Fi and Fn in the forward path and Fn is on a different or new antenna, antenna tilt, antenna orientation, or bad cables and connections should all be suspected. In some cases, we might have to re-sweep the antenna or re-calibrate the power transmitted at the site. For the reverse path, since all carriers share the same base station receive antennas and receive units, any fault in these components will affect all carriers equally. In addition to antenna and cell problems, outside interference in one of the carriers transmit or receive bands is another factor that can cause and imbalance between carriers.



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Note: BCR/CBR attenuations should not be used to match coverage area. In the core area, the attenuation should be identical for all carriers on the same antenna face. Using different attenuation values to match the coverage masks the true reason for the coverage mismatch.

Note: Most first pass RF parameters except BCR/CBR can not be individually adjusted for a specific carrier. An adjustment made for one carrier will affect all carriers. If changing parameters is necessary, the affected areas must be re-driven and the data analyzed to ensure that Fi coverage has not been degraded.

2. Border optimization LDAT can process the handoff data and provide the plot of handoff locations overlaid on Ec/Io Max Finger for troubleshooting purpose. The ALERT text file also gives the PN offset(s) of the antenna face(s) that the call is handing off to and the new frequency. By parsing the drive test binary files using either NPAR or Friendly Viewer program, the RF engineer will be able to see the signal strengths of the active and non-active pilots present before and after the handoffs. This is especially helpful to optimize the cdhnl neighbor list and adjust the handoff location if necessary. Since all Lucent supported inter-frequency handoff configurations are discussed in great details in [4] and [11]we will not repeat them. In this section, we will look at some remedial actions to fix inter-frequency handoff failures for the two handoff configurations that are most commonly used and recommended by Lucent. Other configurations are also described in those two documents..

[1] Translation Adjustments: The translation adjustments for the different types of recommended border sectors are discussed below

CDMA-CDMA Directed Handoff with CIFHOTI (CDMA Inter-Frequency

Handoff Trigger Improvement) trigger and Multiple Pilot Inter-Frequency Handoff (CMPIFHO) enabled

The translations for MPIFHO sectors include the Border Sector Loss Threshold (TCBSL), the Border Pilot vs. Interior Pilot Threshold (TCBIP), the BCR/CBR attenuation, and the cdhnl RC/V form. These translations work together to determine the trigger point for the handoff. The TCBSL is the primary translation used to change the handoff location. The initial value for TCBSL should be set to 3. In general, increasing this value moves the handoff away from the border sector. Decreasing this value will have the opposite affect. The default value for the TCBPIP translation is set to 3.0. The TCBPIP parameter is used to determine when the border sector loss metric should be computed in case both border pilots and traffic (non border) pilots are present in the Active Set. This value should not be modified except under the following two conditions: An interior pilot is in the active set at the time of the inter-frequency

handoff Adjustments to the TCBSL parameter have no affect



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In general, decreasing the value of TCBPIP parameter will tend to cause the border sector loss metric to be computed closer to the border sector. Increasing this parameter will have the opposite affect. In addition to the above translation parameters, adjustments to the cdhnl form for the border sector may also be made. If a strong pilot is seen immediately after the inter-frequency handoff and is not part of the active set, that pilot should be added to the cdhnl form or moved up in priority if it is already in the form. The BCR/CBR attenuation controls the strength of the border sector pilot. In general, increasing the attenuation of the border sector will move the inter-frequency handoff closer to the cell. However, it is not generally recommended to change the attenuation unless the problem cannot be fixed using the TCBSL and TCBPIP parameters.

Pilot Only Sectors The main translations for pilot only sectors are Tcomp or Tadd and BCR/CBR attenuation. The value of Tcomp or Tadd affects the point where the trigger happens. Increasing this value will, in general, for the handover closer to the pilot only sector (requires higher Ec/Io levels of the pilot only sector). These parameters are generally adjusted to stop false handovers in the core area caused by pilot only sectors. The Tcomp and Tadd parameters must be adjusted for all sectors around the border sector to ensure the controlling cell has the required translation value.

Note: Since these two translations, especially Tadd parameter, will affect all carriers, the entire area around the cell must be re-driven to ensure the change does not adversely affect any of the other carriers

The attenuation controls the Ec/Io from the pilot only sector for the new carrier. Increasing the attenuation will move the handover closer to the cell. This parameter is usually adjusted for the outward facing pilot only sectors.

[2] Border configuration adjustments Border configuration adjustments are usually performed when there are problems that cannot be solved using the basic translation parameters such as mobile sneak out, handoff in the core area. [3] Antenna adjustments The antennas should be checked prior to optimization. Therefore, there should not be a need to adjust the antennas for the new carrier during optimization. If for any reason, the antenna needs to be changed, the area must be rechecked to ensure there is no degradation to the underlying carriers.



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5.2.2.1.1 Cold Start 3G System The procedure to analyze data for the loaded coverage test data is similar to that for the unloaded conditions. The loaded conditions are more likely to expose low coverage areas as cells shrink with loading. There may be higher instances of dropped calls as a result. Some cell site power and/or antenna adjustments may be necessary to improve coverage. Testing will be iterated until satisfactory performance is achieved. Certain complex problems requiring additional time/effort can be deferred to system-wide optimization tests. Some of the key performance metrics to evaluate include average Full Rate FER on each link, coverage, mobile transmit power and dropped call statistics. These performance indicators can be validated against the contractual agreements. This will help identify the trouble spots that may need further fine-tuning. 5.2.2.1.2 3G Migration Scenarios Scenario 1 There is no need for optimization since the 3G-1X Voice should perform equal to or better than a 2G network under similar RF conditions. If the customer requires, a validation drive test might be done with 1 2G full rate Markov call and 1 3G full rate Markov call on F2. LDAT 3G generated plots of the performance metrics will be compared between the two phones. Scenario 2 The optimization procedures are similar to those of a 2G multi-carrier system. It is recommended that a 2G full rate Markov call and a 3G full rate Markov call is placed on F2 and F3, respectively. For each sector, the F2 Ec/Io plot should be carefully compared to the F3 Ec/Io plot, and any significant difference in the F2 and F3 coverage footprint should be identified. If a sectors F3 coverage foot print is much smaller than that of F2, the entire transmit path of F3 on that sector should be carefully examined: antennas, power calibration, cable connections, hardware issues, etc. Other metric plots are also compared to get the overall performance of F3 compared to F2. Scenario 3 Similar to the scenario 1, there is no need for RF optimization in the core 3G service area. The validation drive test with a 3G full rate Markov and a 2G full rate Markov call on F2 may be performed to compare the performance between 3G and 2G after the 3G to 2G handoff border is optimized. The validation drive data then will be processed and analyzed in the same manner as in the scenario1. The handoff from 3G to 2G on the same carrier (F2) will be analyzed in Section 8.2.1 Scenario 4



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It is evident an inter-frequency from 3G to 2G handoff border is required. Only a validation drive is required at the core of 3G service area and the data analysis is conducted similar to the scenario 2. The analysis of inter-frequency 3G to 2G handoff will be discussed in Section 8.2.2.

5.2.2.2 3G Combined Voice/Data Deployment

5.2.2.2.1 Cold Start 3G System In order to optimize a 3G Voice/Data capable, a full rate Markov call and a 3G data call are set up on the 3G carrier, during the drive test. The procedure to analyze data for the loaded coverage test is similar to that for the unloaded test. The loaded conditions are more likely to expose low coverage areas as cells shrink with loading. This will help validate coverage adjustments, performed earlier during unloaded tests, under the stresses of RF load. In the worst case, it may require resetting some of the RF parameters to improve the soft handoff overlap and maintain call reliability. Under forward link loading, the reduced handoff diversity may increase mobile transmit power requirement relative to the unloaded tests. Since the loaded tests utilize fixed attenuation on the mobiles reverse link, any increase in the mobile transmit power in excess of the attenuation value could be attributed to coverage pull back on the forward link. This method could be an indicator of the reverse link impact. This requires comparing unloaded and loaded mobile transmit power levels (FCH), especially, in the soft handoff zones using data from the full rate Markov call. Testing will be iterated until satisfactory performance is achieved. Certain complex problems requiring additional time/effort can be deferred to the system optimization. Some of the key performance metrics to evaluate include average FCH FER on each link, SCH FER on the forward link, extent of coverage in terms of Max Finger Pilot Ec/Io, mobile transmit power, dropped call statistics, data throughputs and assigned FSCH rates. These performance indicators can be validated against the contractual agreements. This will help identify the trouble spots that may need further fine-tuning. 5.2.2.2.2 3G Migration Scenarios Scenario 1 It is not necessary to optimize 3G1X Voice on F2 since the system has been optimized for 2G and 3G 1X Voice performs equal to or better than 2G under similar RF conditions. The primary optimization focus will be on creating dominant pilot regions in the network as detailed in the case of cold start 3G networks. The degree of the optimization, however depends on the overall flexibility available to adjust parameters not just for the 3G carrier (F2), but underlying carriers as well. Depending on the available fine-tuning flexibility, one of the two options can be pursued:

1. Option 1: Limited fine-tuning flexibility No coverage fine-tuning is allowed. This then simply reduces the optimization procedures to validation tests only. These tests will be executed in two phases 2G/3G1X voice validation tests, exactly as in the case of 3G1X voice only as discussed in Section 7.2.2.1, and 3G1X data performance tests.



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The data performance tests will also be similar to the system wide 2G/3G voice validation tests, with the exception that a 3G 1X data call is made on F2 for downlink and uplink. Some small amount of data specific fine-tuning, such as the anchor hysteresis threshold, may be made. 2. Option 2: Flexibility to make coverage changes on all carriers The optimization process can also be executed in two phases first phase where system drive tests are performed with two phones on F2 (2G full rate Markov call and 3G1X high speed data call); and second phase where after finishing data optimization, a 2G/3G1X voice validation run is performed using 1 2G full rate Markov call and 1 3G full rate Markov call on F2. For the first phase, many of the optimization techniques will be similar to those used for 3G1X voice/data cold start. Iterative testing will be performed to improve data throughput in problem areas. Multiple runs will also be needed to test downlink and up link high-speed data performance. The second phase of option 2 is similar to the 2G/3G1X Voice validation tests as detailed in the scenario 1 of 3G Voice only networks.

Scenario 2 Depending on the available option, the optimization will be as follows:

If option 1, the tests will be performed in two phases 2G/3G Voice validation tests, exactly as in scenario 2 of a 3G Voice only deployment, and 3G data performance characterization tests on F3, as described in scenario 1, phase 2 of option 1.

If option 2, The optimization process can also be executed in two phases first phase

where system drive tests are performed with a 2G full rate Markov call on F2 and a 3G1X high speed data call on F3; and second phase where after finishing data optimization, a 2G/3G1X voice validation run is performed using a 2G full rate Markov call and a 3G full rate Markov call on F2 and F3, respectively.

For the first phase, many of the optimization techniques will be similar to those used for 3G1X voice/data cold start. Iterative testing will be performed to improve data throughput in problem areas. Multiple runs will also be needed to test downlink and up link high-speed data performance. The second phase of option 2 is similar to the 2G/3G1X Voice validation tests as detailed in the scenario 2 of 3G Voice only networks. Scenario 3 The configuration results in 3G to 2G same frequency handoff border at the edge of the 3G footprint. Note that the handoff is applied to 3G Voice only. 3G data calls are simply released by the system as soon as the border triggers, which are identical to the 3G Voice ones, are met. This scenario requires three main optimization steps:



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First optimize 3G to 2G same-frequency handoff borders as in Section 8.2.1. If option 1, perform 2G/3G1X Voice validation tests throughout the 3G1X coverage

area, including border zones. The data analysis is as in the scenario 1 for voice only. If option 2, then optimize F2 for 3G1X data. In this case, it will really involve joint F1/F2 coverage adjustments. The procedures to improve data throughput are similar to those of a 3G Voice/Data cold start network.

If option 1, perform 3G1X data characterization tests (as in phase 2 of option 1 in scenario 1). If option 2, conduct 2G/3G1X Voice validation runs throughout the 3G1X coverage region including border zones as in the scenario 1 for voice only.

Scenario 4 This scenario is a combination of scenarios 2 and 3 discussed earlier. Combining the two sets of procedures, we obtain three main optimization steps:

First optimize 3G to 2G inter-frequency handoff borders as in Section 8.2.2. If option 1, perform 2G/3G1X Voice validation tests throughout the 3G1X coverage

area, including border zones. The data analysis is as in the scenario 2 for voice only. If option 2, then optimize F3 for 3G1X data. In this case, it will really involve joint F1/F2/F3 coverage adjustments. The procedures to improve data throughput are similar to those of a 3G Voice/Data cold start network.

If option 1, perform 3G1X data characterization tests on F3 (as in phase 2 of option 1

in scenario 1). If option 2, conduct 2G/3G1X Voice validation runs throughout the 3G1X coverage region including border zones as in the scenario 2 for voice only.

6 System-Wide Optimization Test

6.1 Introduction

The system-wide optimization test is a loaded test performed after the cluster tests have been completed for all clusters in the network. After the cluster testing, most of the problems requiring Primary and Secondary pass parameters optimization should have been resolved. The system optimization is a continuation of the cluster optimization.

6.1.1 Data Analysis for 2G Network The system-wide optimization will focus on adjusting the CDMA parameters to optimize coverage in the remaining problem areas, especially those existing in the cluster overlap regions. The system is optimized as a seamless whole without artificial boundaries. The overall performance statistics with the entire system activated is calculated. Appropriate parameter adjustments will be made to solve problems discovered during the test. The strategies to improve system performance are very much similar to those of the 2 previous tests. Tests will be iterated until satisfactory performance is achieved. The field teams should escalate problems too complex to resolve to appropriate CDMA engineering support teams.



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At the conclusion of the system wide drive, the aggregate statistics should be processed to obtain an estimate of the overall CDMA performance. Primary results would include cumulative distribution functions (CDFs) of pilot Ec/Io, forward and reverse FER, mobile transmit power, mobile receive power.



All stated above for a 2G deployment are also true for a 3G Voice deployment.


6.1.2.2.1 Cold Start 3G In addition to drive testing with a full rate Markov call and a data call with high speed transfer on the forward link, it is necessary to evaluate performance with high-speed data transfer on the reverse link to ensure that forward link data optimization does not lead to unacceptable performance on the reverse link. Besides the point that was just mentioned above, the data analysis for system-wide test is similar to that of the loaded and unloaded runs. At the conclusion of the system wide drive, the aggregate statistics should be processed to obtain an estimate of the overall CDMA performance. Primary results would include Cumulative Distribution Functions (CDFs) of FCH FER on each link, SCH FER on the forward link, Max Finger Pilot Ec/Io, mobile transmit power, data throughputs and assigned FSCH rates. Dropped call rates can also be assessed from full rate Markov as well as data calls. 6.1.2.2.2 3G Migration Scenarios Data analysis for the system-wide test is conducted in a similar manner as in the loaded test.

7 Origination and Termination Testing

7.1 Introduction

In some cases, call completion tests can be requested from customers. These may consist of originations by the mobile and/or terminations to the mobile, that is, calls that are placed to the mobile from a standard telephone. Th ere are no origination or termination tests for data calls.



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7.2 Data Analysis

7.2.1 Data Analysis for 2G Network LDAT will be used to parse CAIT data to provide number of origination/termination failures, their locations, total origination/termination attempts as well as origination/termination failure reason. CAIT data will be analyzed via LDAT to generate other plots useful for analysis as well. Plots and histograms of mobile received, transmitted power and mobile Ec/Io can be used. As needed to support the analysis, ROP logs for the corresponding time intervals will be examined. Note that LDAT may under-report the total failures as well as the total call attempts. It is possible some of the calls will fail prior to sending the first access probe (i.e. origination message) or mobile may not receive a page and hence, will not send a page response message (in case of termination test). CAIT will not show any call activity in these cases. Therefore, LDAT will not detect such failures. In order to obtain the true origination/termination failure rate, the total call attempt count from CAITs Call Monitor Dialog box/Procomm script 4 may be used. Origination/termination failure rate will then be 1-[Successful calls from LDAT/Total attempts from CAITs Call Monitor Dialog box/Procomm script]. LDAT also provides a classification of the call failures based on the last message received prior to the failure during the access probes. For example, a failure may be due to no acknowledgement to access probes, channel assignment message not received, etc. The following steps may help to identify the source of the problem for origination failures:

1. Verify the sector that the mobile is trying to originate on makes sense. If it is an overshoot from a great distance away, the signal might be strong for just a very brief time and then fade away. The mobile has established a time reference with the incorrect pilot. The mobile might be able to establish a call but the call will drop right away due to no handoff with surrounding cells. Fixes include attenuating the sector in question, adding neighbors, or opening the neighbor set search window to allow the mobile to reacquire on the correct pilots in the area. If this problem happens a lot in an area, such as on a bridge, then some aggressive changes may need to be employed to fix the problem.

2. The mobile may be timing out without getting a response from the base station.

Successive origination messages from the mobile without a Mobile Station Order Message on the paging channel are an indicator of this. Eventually, the mobile will simply re-acquire on the SYNC channel. Possible causes are:

The mobile may be too far from the cell. If the distance from the cell is close

to or greater than the sector size parameter, then the sector size should be increased to some value greater than the current distance. To be safe, set sector size to the desired value (how far away from the cell should a mobile be allowed to set up on this sector?) plus an additional two miles. If the sector size needs to be increased, it may also be a good idea to increase the number Access Preamble Frames.

4 Please refer to the document MSS-RF-EP064CK Origination and Termination Tests for cdmaOne/CDMA2000 3G1X for more details in setting up origination and termination tests.



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An RF path problem is preventing the base station from detecting the mobiles origination attempts. The receive path at the cell should be checked for errors and/or interference

3. The mobile should be receiving a Channel Assignment Message. If not, then

something at the base station is blocking additional calls. This could be caused by packet pipe failure, ECU failure or other cell hardware problems.

4. If the mobile receives a Channel Assignment Message but fails to properly acquire

the channel, the switch is probably tearing the connection. This condition should be referred to the switch engineer.

If originations are good in an area and terminations are not, then it is not likely to be an RF problem.


7.2.2.1 3G Voice Deployment The procedures used to analyze originations and terminations tests for a CDMA 3G Voice network are similar to those used for 2G networks except the post-processing tool is LDAT 3G.


As stated above, there are not originations and terminations tests for the data service in a 3G Voice/data deployment. Therefore, only the voice service is tested and the procedures are described in 7.2.1.

8 3G-1X Inter-Frequency and Inter-Generation Handoffs Testing

8.1 Introduction When the 3G1X service is overlaid on top of an existing 2G, borders will be defined. To assure the calls will be able to continue without any interruptions, the handoff from 3G1X to 2G has to be optimized. This type of handoff can be either on the same frequency (preferable) or across carriers when:

The carrier on the 2G site is overload or overflow or the 3G1X is implemented on a new carrier.

As the 3G1X service grows with demand, multi-carrier 3G networks are formed. This will lead to the need for 3G1X to 3G1X inter-frequency handoffs.



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Note: These types of handoff only apply to 3G1X voice service. When the handoff triggers, the 3G1X data call will be released and a new 2G IP data call will be established if the 2G IP data feature is supported.

8.2 Data Analysis

8.2.1 3G1X to 2G Same Frequency Handoffs (Inter-generation) As the mobile approaches the edge of 3G1X Voice coverage, a 2G only candidate pilot will trigger a 3G1X to 2G handoff as soon as it is strong enough to be reported on the Pilot Strength Measurement Message (PSMM), and either one of these two conditions holds true:

The combined Active Set pilot strength is less than 10 dB. The candidate pilot is stronger than the dominant Active Set pilot

The threshold 10dB in the first condition is hard coded. Note that the call will be in soft handoff right after the handoff, regardless if the CMPIFHO feature is activated or not. Most of the times, the handoff failed due to a strong interference from a 2G only pilot that is reported to the 3G site by the mobile too late. Some troubleshooting methods for this kind of inter-generation handoff will be described in the following sections.

8.2.1.1 If the call drops before handoff:

1. Set the request for pilot measurement interval parameter (ceqface form) to a non-

zero value on the 3G1X border sectors where we have high level of dropped calls due to failed handoffs and the surrounding 3G cells. This will help to detect the strong pilot sooner (satisfies the 2nd condition) and trigger the handoff before that pilot becomes a strong interference.

2. Lower Tcomp on the 3G1X border sectors where we have high level of dropped calls due to failed handoffs and the surrounding 3G cells. The reason is the mobile only generate a PSMM to report the strongest candidate condition when this pilot exceeds the strongest active pilot by at least Tcomp dB. By lowering Tcomp, the mobile will report the candidate sooner and the transition can happen successfully

3. Adjust the coverage of the cells in the border area to move the handoff location to a

more favorable environment. This may be done with BCR/CBR attenuations adjustments. If the border is temporary, it is not recommended to use this method. Except for the case of border 3G facing outward sectors, any change in BCR/CBR has to be applied on all carriers to avoid call access failures due to footprint mismatch.



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8.2.1.2 If the handoff happens at unexpected locations:

1. A strong overshoot from a 2G only sector to the interior of the 3G footprint will cause the handoff to occur inside the 3G service core area. This will affect the capacity of the 3G cells. The fix is to reduce the power of that 2G pilot by means of changing BCR/CBR or adjust antenna downtilt, etc.

2. A 3G call is setup in the 2G only area due to an overshoot from a 3G cell. This might

not be serious since the 3G call will automatically handoff to a 2G cell as soon as the handoff conditions are satisfied. The problem will be addressed if the handoff fails. In that case, the 3G overshoot pilot power will be attenuated.

8.2.2 3G1X to 2G Inter-frequency Handoffs (Inter-generation, Inter-frequency) The 3G1X to 2G inter-frequency handoff procedures and optimization are no different than those of 2G inter-frequency handoffs. Lucent recommends the use of Directed Handoff CDMA Inter-Frequency Handoff Trigger Improvement (CIFHOTI) along with the CMPIFHO feature whenever possible. The pilot assisted handoff method, which uses pilot only cell, may only be used in certain unique cases. Please refer to [4] and [11] for the details. Some highlights for troubleshooting techniques are provided in Section 5.2.1of this document.

8.2.3 3G1X to 3G1X Inter-frequency Handoffs The handoff methods are exactly the same as in 2G inter-frequency handoffs. Since the 2G inter-frequency handoffs are discussed in great detail in [4] and [11], we are not going to repeat.

9 Common CDMA Optimization Techniques This section presents the problems and remedies that are common for a 2G Voice network, a 3G Voice only network and a combined 3G Voice/Data network.

9.1 No Service

This is typically caused by lack of adequate signal from the mobile. This could be due to weak reception for Pilot, Paging or Access channels.

9.1.1 Inadequate Pilot Signal Strength from Serving Sector Forward Link If CDMA calls cannot be originated because of inadequate pilot signal strength from a serving sector, the problem is most likely due to a coverage hole created by excessive path loss. The excessive path loss could be due to blockages from terrain, buildings, trees, or any other radio obstacle. For CDMA systems, the maximum allowable path loss will shrink as a function of system load; therefore, coverage holes which were not evident during light load conditions may suddenly appear under heavy traffic load.



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The primary CDMA tuning parameter, which can be used to address coverage holes, is the BCR/CBR attenuation. By increasing the transmit power from the best serving sector in steps of approximately 2 dB, it should be possible to determine if the coverage hole can be adequately filled. Unfortunately, in many cases increasing transmit power will not be able to solve the problem; for example, due to the limited power output from CDMA minicells, very little transmit power margin is available for use in RF optimization. Also, mobile has finite power to close the reverse link. Other more cumbersome techniques can be used to fix coverage holes. Cell site antennas can be changed to higher gain varieties (narrower vertical or horizontal beamwidth) provide more signal strength in the desired area. Of course, increasing the antenna gain may fix one coverage problem, while at the same time creating many others. In some cases, re-orienting the antenna s pointing azimuth may be useful for filling coverage holes in particular areas. Adjusting antenna downtilts at the serving sector may also allow more energy to be radiated in the vicinity of the coverage hole. In cellular deployment scenarios, any changes in antenna patterns or downtilt angles will also affect the underlying AMPS network, and therefore, limited degrees of freedom may be available. As a last resort, an entirely new CDMA cell may be required. Another option that is currently under investigation involves the use of low-cost CDMA repeaters to rebroadcast signals from existing cell sites, as is done today to fill in AMPS coverage holes.

9.1.2 Paging or Access Channel Message Failure

In some cases, the paging and access channel performance of the CDMA system may not exactly match the traffic channel coverage. For example, the paging channel does not benefit from forward power control or from soft handoff combining gain. If paging channel transmit powers are not set correctly, mobiles may be able to receive acceptable pilot and sync channels, but may fail because of

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