This document provides guidance on optimizing the RxQuality key performance indicator (KPI) for GSM base station subsystems (BSS). It defines RxQuality as reflecting the bit error rate on the Um interface. The document analyzes factors that influence RxQuality, such as network planning, interference, power control and hardware faults. It then describes processes and methods for analyzing RxQuality problems, including investigating interference sources and reducing transmit power. Optimization techniques include eliminating intermodulation, frequency planning, frequency hopping checks and replacing aged radio frequency hardware. The document aims to help engineers address quality issues and improve network KPIs.

1. GSM BSS Network KPI (RxQuality) Optimization Manual INTERNAL
Product name Confidentiality level
GSM BSS INTERNAL
Product version Total 17 pages
V00R01
GSM BSS Network KPI (RxQuality) Optimization
Manual
(For internal use only)
Prepared by GSM&UMTS Network
Performance Research
Department
Dong
Xuan
Date 2009-01-05
Reviewed by Date yyyy-mm-dd
Reviewed by Date yyyy-mm-dd
Granted by Date yyyy-mm-dd
Huawei Technologies Co., Ltd.
All rights reserved
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2. GSM BSS Network KPI (RxQuality) Optimization Manual INTERNAL
Revision Record
Date Revision
version
Change Description Author
2009-01-05 1.0 Draft completed. Dong
Xuan
2014-06-18 Huawei Confidential Page 2 of 18

3. GSM BSS Network KPI (RxQuality) Optimization Manual INTERNAL
GSM BSS Network KPI (RxQuality) Optimization
Manual
Keyword: RxQuality
Abstract:
This document analyzes factors that affect the downlink RxQuality on the
BSS side. Based on the analysis, some methods are elaborated to quickly
improve the downlink RxQuality. The Um quality is also to be improved to
avoid poor RxQuality failure, call drop, and frame deletion resulted from the
voice decoding decrease in the call. Some measures for optimizing this KPI
are provided in this document to help field engineers address quality
problems. This document targets at optimizing network KPIs and improving
network quality so as to make sound preparations for the final network
delivery.
Keyword: RxQuality (Downlink)
List of abbreviations:
Abbreviations Full spelling
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4. GSM BSS Network KPI (RxQuality) Optimization Manual INTERNAL
Contents
1 Basic Principle.........................................................................................................6
1.1 Definition......................................................................................................................................6
1.2 Theory Introduction......................................................................................................................6
1.3 Recommended Formula................................................................................................................6
1.4 Signaling Procedure and Statistical Point.....................................................................................6
2 Influencing Factors................................................................................................7
3 Analysis Process and Optimization Methods...................................................8
3.1 Analysis Process............................................................................................................................8
3.1.1 Procedures for RxQuality Problem Location..........................................................................8
3.2 RxQuality Optimization Methods.................................................................................................9
3.2.1 Poor RxQuality on Entire Network.......................................................................................10
3.2.1.1 Processing Methods............................................................................................................10
3.2.1.2 Traffic Measurement Analysis............................................................................................11
3.2.1.3 Alarm Analysis....................................................................................................................11
3.2.2 Passive Intermodulation........................................................................................................11
3.2.2.1 Processing Methods............................................................................................................11
3.2.2.2 Traffic Measurement Analysis............................................................................................12
3.2.2.3 Alarm Analysis....................................................................................................................12
3.2.3 Intra-Network Interference...................................................................................................12
3.2.3.1 Processing Methods............................................................................................................12
3.2.3.2 Traffic Measurement Analysis............................................................................................12
3.2.3.3 Alarm Analysis....................................................................................................................13
3.2.4 Inter-Network Interference...................................................................................................13
3.2.4.1 Processing Methods............................................................................................................13
3.2.4.2 Traffic Measurement Analysis............................................................................................13
3.2.4.3 Alarm Analysis....................................................................................................................13
3.2.5 Hardware Fault......................................................................................................................13
3.2.5.1 Processing Methods............................................................................................................13
3.2.5.2 Traffic Measurement Analysis............................................................................................14
3.2.5.3 Alarm Analysis....................................................................................................................14
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5. GSM BSS Network KPI (RxQuality) Optimization Manual INTERNAL
3.2.6 Huawei Anti-Interference Technology..................................................................................15
3.2.6.1 Processing Methods............................................................................................................15
3.2.6.2 Traffic Measurement Analysis............................................................................................16
3.2.6.3 Alarm Analysis....................................................................................................................16
3.2.7 Test Tool and Recommendations..........................................................................................16
3.2.8 Recommendations for Configuration and Test.....................................................................16
4 RxQuality Optimization Cases..........................................................................17
4.1 Low RxQuality in Kenya............................................................................................................17
4.2 Enabling Idle Burst Causing Interference Increase and Low RxQuality....................................17
5 Information Feedback.........................................................................................18
5.1 TEMS Test Log of Faulty Cell....................................................................................................18
5.2 Requirements for Existing Network Configuration Data and Traffic Measurement..................18
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6. GSM BSS Network KPI (RxQuality) Optimization Manual INTERNAL
1 Basic Principle
1.1 Definition
The RxQuality is an informal KPI. It identifies the Bit Error Rate (BER) on
the Um interface based on the proportions of downlink RxQuality at various
levels. The RxQuality can reflect the entire network quality. When the
RxQuality is good and no major bug exists in voice processing, you can infer
that the voice quality on the network is good.
1.2 Theory Introduction
In theory, two measures can be taken to improve the RxQuality. One is to
improve the RxQuality and demodulation performance (decoding the BER)
with the same signals. The other is to decrease interference. In practice, the
latter is an optimization method for improving the RxQuality.
None.
1.3 Recommended Formula
None.
1.4 Signaling Procedure and Statistical Point
None.
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7. GSM BSS Network KPI (RxQuality) Optimization Manual INTERNAL
2 Influencing Factors
According to cases and experiences in solving this problem, the following
factors affect the downlink RxQuality:
 Network planning
 Data configuration
 Frequency planning
 Coverage
 Interference
 Power control
 Interference-Based Channel Assignment (IBCA)
 UISS
 ICC
These preceding factors are described in Chapter 3.
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8. GSM BSS Network KPI (RxQuality) Optimization Manual INTERNAL
3 Analysis Process and Optimization
Methods
This section aims to provide baseline recommendations for data configuration.
In addition, it highlights some methods for improving the RxQuality on the
premise that the project is clear of major problems and the coverage is good.
3.1 Analysis Process
The RxQuality reflects the network quality from two perspectives. The first is
TRX-based counters, and the second is drive test or customer complaints. The
RxQuality is improved mainly by eliminating or reducing interference. The
interference is eliminated through interference source investigation to reduce
intermodulation, proper planning of network frequency, frequency hopping
check, and replacement of aged RF hardware. The interference is reduced by
decreasing the transmit power of RF components while ensuring the quality,
and intelligently choosing the frequencies or timeslots with little interference
for channel assignment. The quality and capacity are contradictory. When the
BTS configuration exceeds a specific limit, the quality is affected.
3.1.1 Procedures for RxQuality Problem Location
The common procedures for RxQuality problem location are described as
follows:
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9. GSM BSS Network KPI (RxQuality) Optimization Manual INTERNAL
3.2 RxQuality Optimization Methods
The poor RxQuality may be caused by the following factors:
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10. GSM BSS Network KPI (RxQuality) Optimization Manual INTERNAL
Hardware transmission fault (faulty TRX and antenna system in combination
mode)
 Improper data configuration
 Intra- network interference
 Inter-network interference
 Clock fault
 Coverage and uplink-downlink imbalance
 Improper power control settings
When the RxQuality is poor, the reasons for poor RxQuality are classified in
terms of the preceding factors. Then, the RxQuality is improved from two
perspectives. Check whether the poor RxQuality occurs on the entire network
or only in some cells or BTSs. If poor RxQuality occurs on the entire network,
causes are investigated in terms of internal network interference and external
network interference. If poor RxQuality only occurs in some cells or BTSs,
the procedures in section 3.1are taken to investigate the causes. The
RxQuality is improved by examining interference, modifying data
configuration, replacing some hardware, cleaning feeder and jumper
connectors, and replacing aged feeders.
3.2.1 Poor RxQuality on Entire Network
According to statistics of traffic measurement counters, if the poor RxQuality
occurs on the entire network, it cannot be optimized through optimization in
only some cells or BTSs. You are advised to follow the procedures described
in section 3.2.1.1.
3.2.1.1 Processing Methods
For the poor RxQuality of the entire network, check the frequency planning.
In scenarios of S4/4/4 or above with low band (5 MHz) and a certain
frequency hopping (1x3), the noise floor of the entire network is high. In
addition, the cell coverage is not well controlled in the network planning. The
inter-cell coverage therefore causes co-channel and adjacent-channel
frequency collisions. The interference is comparatively large, which causes
poor RxQuality. On the network with non-synchronized frequency hopping in
sequence, the continuous frequencies may cause continuous collisions, which
may also affect the RxQuality.
In summary, the poor RxQuality occurs in narrow band with large
configurations. You are advised to take measures to control the coverage of
each cell to avoid inter-cell coverage that may cause co-channel or adjacent-
channel interference. The random frequency hopping instead is adopted to
avoid low RxQuality. In the optimal solution, you need to decrease the BTS
configuration and site distance or divide cells, and plan the network properly.
Besides, on the network with high noise floor, the RxQuality can be greatly
improved by reducing the network noise floor and interference through the
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11. GSM BSS Network KPI (RxQuality) Optimization Manual INTERNAL
power control.
If the preceding adjustments still cannot solve the problem, the latest R&D
results of the Performance Dept are applied. These R&D results include
synchronization network, ICC technology, and IBCA. The RxQuality is
improved without reducing the network capacity.
The maximum RxQuality is not the ultimate aim of the network optimization. The
ultimate goal is to enrich the customer experience according to different bandwidths,
capacity requirements, traffic models, and network scenarios.
3.2.1.2 Traffic Measurement Analysis
None.
3.2.1.3 Alarm Analysis
None.
3.2.2 Passive Intermodulation
3.2.2.1 Processing Methods
When two RF signals are transmitted to a nonlinear component, or transmitted
through a discontinuous transmission medium, a series of new frequency
components are generated. These frequency components satisfy the following
formulas. Suppose the frequencies of these two signals are f1 and f2 (absolute
frequencies).
Fn = mf1 + nf2, and Fn = mf1 – nf2
The most common types are third-order, five-order, and seven-order
intermodulations. The RxQuality of the system is affected when the
intermodulation components are transmitted to the Rx band and the level
exceeds a specific limit.
The intermodulation interference is generated mainly because the frequency
interval is short. In this case, the interference can be eliminated by increasing
the cell frequency intervals.
[m–n] = 1, m + n = x, in which x stands for x order.
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12. GSM BSS Network KPI (RxQuality) Optimization Manual INTERNAL
3.2.2.2 Traffic Measurement Analysis
None.
3.2.2.3 Alarm Analysis
None.
3.2.3 Intra-Network Interference
3.2.3.1 Processing Methods
The intra-network interference is classified into two categories: co-channel
interference and adjacent-channel interference.
The frequency reuse is adopted on the GSM network. When the frequency
reuse radius of two cells in the same frequency or adjacent frequencies is
improperly small, the co-channel or adjacent-channel interference is easy to
generate.
The following methods are used for addressing the intra-network interference.
Check whether the frequency planning, especially the co-channel and
adjacent-channel frequency reuse, is proper.
Besides, the coverage of each cell is controlled in accordance with practical
situations. It is important especially for the network with heavy traffic and less
frequency resources to control the coverage and maintain proper co-channel
and adjacent-channel frequency reuses.
The data should be configured accurately. The proportions of inter-cell co-
channel and adjacent-channel frequencies should be proper in the data
configuration.
The intra-network interference can be solved through frequency optimization,
antenna adjustment, and coverage control. In addition, tools such as Nastar
can be used for frequency optimization. Check the co-channel and adjacent-
channel frequencies and recommended frequencies by entering engineering
parameters. The frequencies with severe interference are replaced to greatly
improve the RxQuality.
3.2.3.2 Traffic Measurement Analysis
None.
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13. GSM BSS Network KPI (RxQuality) Optimization Manual INTERNAL
3.2.3.3 Alarm Analysis
None.
3.2.4 Inter-Network Interference
3.2.4.1 Processing Methods
The inter-network interferences can be classified into the following three
categories:
Repeater interference: It can be solved by communication with repeater
vendors.
Inter-RAT interference: The filter is added to filter out interference. In
addition to frequency modification, the co-site BTSs do not use the E-GSM
frequencies. Besides, the gains of two antennas can be reduced by increasing
the space between two antennas or antenna tilt.
Security equipment interference: Information about the BTSs with
interferences is collected. You are advised to replace the security equipment
with the recommended Interference Unit (IU).
3.2.4.2 Traffic Measurement Analysis
None.
3.2.4.3 Alarm Analysis
None.
3.2.5 Hardware Fault
3.2.5.1 Processing Methods
The interference caused by hardware fault is mostly due to the passive
intermodulation interference.
To solve this problem, multiple hardware operations are required. Due to
frequency reuse in the network operation, difficult problem location, and
multiply faulty cells, a special team is established to solve this problem
quickly.
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14. GSM BSS Network KPI (RxQuality) Optimization Manual INTERNAL
The idle burst authentication is transmitted through the LMT.
Check the data of interference band level 3 to level 5 according to the traffic
measurement. Check whether the interference bands follow some rules and
whether the interference bands are related to time, traffic, weather, and cell
location. Check whether similar interference band problems used to occur.
Finally, perform comprehensive analysis.
If the interference band persists, the interference band is enhanced with the
traffic increase, or the external BTS interference is excluded by replacing the
frequencies, you can infer that it is internal BTS interference. Take the
following measures:
Check whether the TRX or Combining and Distribution Unit (CDU) fault
causes the inter-network interference by blocking and replacing boards.
Check whether the jumpers are connected to the cabinet top outlet and feeder
properly. If the ports do not match, the front end circuit of the BTS may be
unstable. In this case, the spontaneous vibrations may generate to bring
interference to the internal bandwidth.
Check whether the antenna system generates the passive intermodulation by
disabling some TCH TRXs or exchanging antenna systems. In this case, you
can determine whether the interference is caused by antenna intermodulation.
The interference is eliminated mainly through RF optimization. For details,
see the GSM Interference Analysis Guide.
GSM I nt er f er ence
Anal ysi s Gui de 020429- A- 1. 0. zi p
3.2.5.2 Traffic Measurement Analysis
None.
3.2.5.3 Alarm Analysis
Three types of alarms need to be observed: antenna alarm, TRX alarm, and
BTS clock alarm.
If any one of the following alarms is reported, see the BSS Alarm Reference
for specific processing methods.
Alarm ID and Name
4154 TRX main clock alarm
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15. GSM BSS Network KPI (RxQuality) Optimization Manual INTERNAL
4156 TRX slave clock alarm
4184 TRX clock critical alarm
4708 Clock Reference
Abnormal Alarm
4732 TMU clock critical alarm
4734 Master TMU clock alarm
4760 13M Maintenance Alarm
4102 LAPD Alarm
4104 TRX configuration Alarm
4108 Radio link critical Alarm
4114 TRX interior I/O alarm
4136 TRX Hardware alarm
4144 TRX VSWR alarm
4192 TRX communication
alarm
4714 E1 Local Alarm
5286 CDU VSWR Level 1
Alarm
5284 CDU VSWR Level 2
Alarm
5326 Level 1 VSWR Alarm
5328 Level 2 VSWR Alarm
3.2.6 Huawei Anti-Interference Technology
3.2.6.1 Processing Methods
Huawei has the following anti-interference technologies. These technologies
facilitate the reduction in network interference and improvement in the
RxQuality to enrich the end user experience.
List of Huawei anti-interference technologies:
UISS
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16. GSM BSS Network KPI (RxQuality) Optimization Manual INTERNAL
IBCA
Flexible MAIO (FLEX MAIO)
Power Control, DTX
3.2.6.2 Traffic Measurement Analysis
None.
3.2.6.3 Alarm Analysis
None.
3.2.7 Test Tool and Recommendations
The TEMS that is accepted by the industry and widely used serves as the test
tool. The drive test is required for the cell with low RxQuality. The low
RxQuality in some cells or BTSs can be detected and solved by drive test.
3.2.8 Recommendations for Configuration and Test
For network configurations, see the latest GSM BSC6000 Performance
Parameter Baseline (V900R008) V2.0. The configurations are performed
according to different scenarios. When the RxQuality is low, you need to
check the data configuration that is greatly different from the parameter
baseline.
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17. GSM BSS Network KPI (RxQuality) Optimization Manual INTERNAL
4 RxQuality Optimization Cases
4.1 Low RxQuality in Kenya
In Kenya, the configuration of existing network has multiple sites in S8/8/8
configuration, which is very large. The entire network uses 1*3 RF frequency
hopping. The RxQuality is not satisfactory. According to check results, the
existing network uses the latest BSC version. The power control parameters,
however, are set according to second generation power control algorithm
rather than the parameter configuration baselines. After the parameters are set
by using the third generation power control algorithm, the proportion of
RxQualtiy 0–3 is increased by 12% compared to that by using the second
generation algorithm.
4.2 Enabling Idle Burst Causing Interference
Increase and Low RxQuality
After the site is swapped, the network quality is decreased by 3% to 4%
according to the drive test results. The hardware, frequency planning, and
inter-cell engineering are proper. The RxQuality is decreased by 2% to 3%
compared with that of the existing network. Other KPIs are proper.
According to analysis, after the idle bursts are enabled, they cannot be
automatically disabled. In this case, the idle TRX timeslots are transmitted in
full power, and the BER is increased, thus, the RxQuality deteriorates. When
the idle burst is disabled manually, the Um quality of the entire network is
greatly improved. The RxQuality is improved by 2%, which is almost the
same as that of the original network.
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18. GSM BSS Network KPI (RxQuality) Optimization Manual INTERNAL
5 Information Feedback
5.1 TEMS Test Log of Faulty Cell
The cell information table in .cel format of the TEMS test is sent back with
the log.
5.2 Requirements for Existing Network
Configuration Data and Traffic Measurement
The latest data configuration and engineering parameter list on the network
are specified. Provide the traffic measurement counters of continuous two
days. The traffic measurement counters are described as follows:
MR Measurement > Receive Quality Measurement per TRX
MR Measurement > Interference Band Measurement per TRX
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