This document describes how to use a mobile station (MS) to locate network problems in CDMA2000 networks. It explains how to view debugging screens on different MSs to check indices like pilot strength, receive level, and transmit level, which can indicate issues with forward or reverse coverage. It also discusses using reverse frame error rate tests on the network side to evaluate connection quality and voice quality. The document provides guidance on interpreting these metrics and diagnosing potential problems based on the results, like interference issues affecting transmit levels or poor coverage in certain areas.

1. Document No. Product name Cdma2000
User Product Version
Compiled by:
Wireless Network System
Research Department
Version 1.00
Cdma2000 Network Problem Location
with Mobile Station
Prepared by: Li Jie Date: 2003/1/22
Reviewed by: Ma Mingming Date: 2003/2/18
Reviewed by: Xiong Qiang Date: 2003/2/18
Approved by: Tao Maodi Date:
Huawei Technologies Co., Ltd.
All rights reserved.

2. Revision Record
Date Revised version Description Author
2003/1/22 V1.0 First draft finished. Li Jie

3. Table of Content
1 Introduction to MS Debug Screen ............................................................................................... 2
1.1 Displaying Debug Screen of H100 MS ................................................................................. 2
1.2 Index Value on Debug Screen.............................................................................................. 2
1.3 Debug Screen of S200 MS................................................................................................... 3
2 Judgment of Forward Coverage .................................................................................................. 4
2.1 Pilot Strength ........................................................................................................................ 4
2.2 Receive Level of MS............................................................................................................. 5
3 Judgment of Reverse Coverage .................................................................................................. 7
3.1 Transmit Level of MS............................................................................................................ 7
3.2 Reverse Frame Error Rate ................................................................................................... 7
4 Judgment of Connection Quality................................................................................................. 9
5 Judgment of Voice Quality......................................................................................................... 10
6 Summary ...................................................................................................................................... 11

4. Cdma2000 Network Problem Location with Mobile Station
cdma2000 Network Problem Location with Mobile Station
Keyword: CDMA, forward coverage, reverse coverage and connection
Abstract: This document describes how to use a Mobile Station (MS) to locate network
problems. That is, judge the forward/reverse coverage by viewing the
indices displayed on the Debug screen of MS. Then locate the network
problems according to reverse Frame Error Rate (FER) and Received
Signal Strength Indicator (RSSI) test on the background. This document
uses H100 MS as an example for the description. For settings of other
CDMA MSs, see the relevant document.
Abbreviations:
Reference:
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5. Cdma2000 Network Problem Location with Mobile Station
1
1.1
1)
2)
3)
4)
1.2
Introduction to MS Debug Screen
Displaying Debug Screen of H100 MS
Switch on the MS;
Input password: ##27732726;
Press the red Power-off key;
Select 3.
The Debug screen is displayed.
Index Value on Debug Screen
Assume that the following information is displayed on the Debug screen:
P232 R085 C0210
03612-00001-1
PAGE Ec: -5.0
RX: -75 TX: NoTx
P232: PN of primary service sector
C0210: System operating frequency
03612: SID
00001: NID
PAGE: Channel mode
Ec: Ec/Io
Rx: Receive level of MS
TX: Transmit level of MS
Though the meanings of two indices (R085 and -1) are unavailable, the network quality
can be evaluated without them, since the major indices of Um interface are given.
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6. Cdma2000 Network Problem Location with Mobile Station
1.3
1)
2)
3)
Debug Screen of S200 MS
Remove the cell of a S200 MS, you will see “S/P NO”. Each “NO” corresponds to a
Service Processing Board (SPC). See the relevant attachment for details.
To display the Debug screen:
Select “Menu”;
Press <0> key;
Input the corresponding No. of SPC.
The Debug screen is displayed.
Assume that the following information is displayed on the Debug screen:
s13842n0001i1
c0210p036r057e04
v489:224t116s003
00 00 0
s13842: SID
n0001: NID
c0210: System operating frequency
p036: PN of primary service sector
r057: Receive level of MS
e04: Ec/Io
The transmit level of MS is not displayed on the Debug screen of S200 MS. Thus the
judgment of reverse coverage is affected more or less.
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7. Cdma2000 Network Problem Location with Mobile Station
2
2.1
Judgment of Forward Coverage
Pilot Strength
In CDMA 1X system, the pilot strength (Ec/Io) is one of the essential parameters that
indicate network forward coverage and co-frequency interference. Due to the
interference-restricted feature of CDMA system, it is crucial to properly control the pilot
strength.
The Ec/Io value of the service area can be obtained from the Debug screen of the MS.
Since the base stations (BTSs) of CDMA system operate in one frequency, how to
eliminate the signal interference between cells is a major consideration in CDMA
network construction. If a sector is assigned with a fixed Ec, the increment of signal
level in any other sector may increase the Io. Hence the Ec/Io of this cell decreases.
When judging the forward coverage effect via the MS, pay more attention to the
overlapped area of the cells. Meanwhile, check the connection sequence of
antenna-feeder (for improper connection) and antenna engineering parameters of each
BTS, based on network topological map, PN list, etc.
If the coverage ranges of some BTSs are not properly controlled, the Ec/Io may be poor
in the overlapped area of these cells. In addition, the serious interference in forward
coverage may also degrade the Ec/Io. This frequently happens to the CDMA 450MHz
network in China. Generally, the Ec/Io above -8dB is ideal. Some operators only
requires that the Ec/Io in 99% of the coverage area should be better than -12dB.
The following example illustrates how to locate network problems using a MS and the
BTS topological map.
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8. Cdma2000 Network Problem Location with Mobile Station
The above figure shows the BTS topological map of a CDMA network. The network
covers a prosperous city in southern China. A newly-developed urban area is located in
the east of the city with a number of luxury residential communities and high buildings.
The old urban area is located in the west of the city, with lower buildings
closely-packed.
As the above figure shows, area A is surrounded by the BTSs of Jinsha Telecom,
Waima Telecom, Information Building and Chaoshan Telecom. The BTS antenna of
Shanzhang Telecom is mounted high above the earth (75 m) and covers other areas.
Thus the coverage of this area is under suspicion. According to the on-foot MS test on
field, the Ec/Io of this area is poor and the signals of the nearby BTSs are of the similar
quality. Moreover, the signals from BTS in the south riverbank can also be received.
There is no dominant service cell in area A. In nearby area to the east of Waima
Telecom, the dominant service cells come from Information Building and Jinsha
Telecom rather than Waima Telecom. Then, observe the radio environment of Waima
Telecom on top of the building. As a result, the area (about 20 m) around sector 1 and
sector 2 of Waima BTS is surrounded by high buildings. So far, the cause is located for
the poor coverage in this area.
This problem can be temporarily eased by adjusting the pilot power ratio, and the
azimuth and down tilt of the antenna. It is also recommended that new BTS(s) be
added to this area in the subsequent engineering.
In a large-scale network, the on-foot MS test will greatly increase the workload. In this
case, use the BTS topological map and administrative map to locate the suspect areas
and then test in these areas with extra attention. Particularly, the indoor environment of
the overlapped area may be the blind-spot of the coverage.
2.2 Receive Level of MS
The MS’s receive level (Rx) and pilot strength (Ec/Io) jointly indicate the effect of
forward coverage and none of them can be absent. In densely-populated urban area,
the BTSs are closely distributed. Therefore, the Rx can be ensured if only the antenna
feeder system is properly designed. However, in rural areas or at the edges of the
service cells, the Rx of the MS is generally around -90dBm, while the Ec/Io is around
-3dB. Obviously, though the signal strength is only -90dBm, half of them can still be
used.
Logically, the call service should be satisfactory if judged by Ec/Io only. However, since
the attenuation can be up to 20dB, the strength of attenuated signals may be weaker
than the receive sensitivity of the MS. Thus the forward bit error occurs to the MS. The
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9. Cdma2000 Network Problem Location with Mobile Station
forward bit error may disable the MS transceiver, incur reverse bit error or even call
drop. Please pay extra attention to it. This may also happen to the ground floors of high
buildings in urban areas.
The MS’s receive level can be viewed from the Debug screen of the MS. Generally, the
areas with receive level above -60dB can receive good service, while those with
receive level under -95dB are blind-spot of the coverage.
The quality of forward coverage is jointly determined by Ec/Io and Rx. The signal
strength displayed on the screen is directly related to the sum of absolute values of
Ec/Io and RxAGC.
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10. Cdma2000 Network Problem Location with Mobile Station
3
3.1
3.2
Judgment of Reverse Coverage
Transmit Level of MS
The transmit level (Tx) is the parameter that reflects the reverse coverage of the
network. There are many factors affecting Tx, such as reverse interference and
improper setting of search window.
In the 450MHz network in China, the reverse interference is a serious problem. In areas
near the BTS (within 1 km), the MS’s transmit level should be under -20dB. The high
transmit level may result from the reverse interference. The reverse interference can be
monitored by using RSSI.
The interference is primarily judged based on the mean value of no-load RSSI. In a new
office with few subscribers, the no-load RSSI level is generally less than -105dBm.
According to the records of Cangzhou office, the mean value of RSSI will not exceed
-95dBm in the presence of multiple services. The RSSI values in traffic measurement
can be used to judge the interference.
If a carrier is seriously interfered, use the Telnet command to connect a PC to the BTS
so as to view the peak value of RSSI. Connect the PC to BTS via Telnet to trace the
TRX resources. In this way, the RSSI mean value, peak value and other information
can be reported every second. The command is Str
infotrace:brdtp=btrm,brdid=XXX,item="rssi", where XXX is the board No. of
resource allocation board (RMU) on Resource Module (RM) subrack.
The MS transmit level can be viewed from the Debug screen of the MS. Note that the
Debug screen of H100 MS only displays “TX: NoTx” in standby status. The actual Tx
value is displayed only when a call is connected or when a call is in progress.
Reverse Frame Error Rate
The reverse FER cannot be obtained on MS side. It should be traced via the
background. It can be used to judge the reverse coverage quality of the network. The
background can only trace the FER of one (or more) MS in a given time. Normally, the
reverse FER should be lower than 1%. Once the reverse FER exceeds 20%, the call
will be frequently interrupted.
Measurement of reverse FER
Enable FER measurement function:
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11. Cdma2000 Network Problem Location with Mobile Station
a. Connect to the FMR board;
b. Enable the print functions of RMM and DBG modules;
c. Input the command FMR DEBUG. The command code is ERASURE frame
measurement startup, and the parameter is the last 10 digits of IMSI of the MS.
Disable FER measurement:
1)
2)
3)
Connect to the FMR board;
Enable the print functions of RMM and DBG modules;
Input the command FMR DEBUG. The command code is ERASURE frame
measurement stop, and the parameter is the last 10 digits of IMSI of the MS.
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12. Cdma2000 Network Problem Location with Mobile Station
4 Judgment of Connection Quality
The connection quality is primarily reflected by the call completion rate and call
connection time. The general connection quality of the network can be evaluated via
dial test in a fixed position using the MS. The call completion rate can be obtained via
traffic measurement. For methods of improving call completion rate, see M2000 Traffic
Measurement Analysis Guide. Currently, Huawei system supports the call connection
time of 3 ~ 4 seconds. The call connection in 450MHz network usually takes longer time.
That is, the average call connection time is 6 ~ 8 seconds or even 10 seconds when
signals are weak. For methods of shortening call connection time, see the relevant
cases and guides.
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13. Cdma2000 Network Problem Location with Mobile Station
5
Table 5-1
Judgment of Voice Quality
The subjective opinion evaluation is widely applied since it complies with people’s
sense of hearing. The major subjective opinion method is Subjective Opinion Scale or
Mean Opinion Score (MOS). The MOS grades the voice quality in five scales. The
method is that dozens of testing engineers listen to the voice calls in the same channel
and grade the quality respectively. Then the average score is calculated based on
these scores. The score of each subjective opinion test may vary with the subjective or
objective factors. To minimize the inaccuracy of the scores, the number of testing
engineers should be sufficient. Meanwhile, provide diversified voice materials and try to
maintain the same environment for the test.
In addition, note that the objective opinion upon voice quality is often related to people’s
listening effect. Therefore, the objective opinion score should also cover the listening
effect scale. The following table lists the quality level, score and description of
corresponding listening effect scale of subjective opinion evaluation.
Subjective opinion score table
Quality level Score Description of listening effect scale
Excellent 5 Relax without attention
Good 4 With slight attention
Fair (Normal) 3 With medium attention
Poor 2 With concentrated attention
Bad 1 Cannot follow even with extra attention
Generally, the subscriber may consider that the voice code with MOS between 4.0 ~
4.5 is of high quality and meets the requirement of toll network. The voice code with
MOS around 3.5 delivers acceptable communication quality and the audience is aware
of the degraded voice quality. However, it does not affect the normal conversation and
meets the requirements of most digital communication systems. Voice code with MOS
under 3.0 is usually called synthesis voice. With such voice quality, the audience can
only follow the conversation, but cannot distinguish the speaker, since the voice is
distorted to some extend.
It is essential to judge the voice quality as the subscriber will eventually evaluate the
quality of network based on the voice.
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14. Cdma2000 Network Problem Location with Mobile Station
6 Summary
When drive test equipment is unavailable, the general network quality can be evaluated
by viewing the Debug screen of the MS and originating calls with the MS. And the
network problem can be located via tools such as traffic measurement and
commissioning console. With the drive test equipment, the MS can be used to test the
coverage blind-spots of the network.
The cellular network should be structured during the network planning phase. However,
since the ideal network structure may not be achieved in the network plan, the goal at
early optimization stage is to construct a network with appropriate structure. As the
backbone of a network, a sound network structure is the most essential factor in radio
network. The software parameter should serve the network structure. The network
structure determines the software parameters. Getting a perfect network structure
makes up 80% of the network optimization work. In the latter stage of network
optimization, the key areas should be optimized based on the traffic measurement. The
optimization covers software parameters on the basis of the entire network, including
power ratio, neighbor cell relation, search window and power control parameter.
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