Huawei

1. eNodeB LTE V100R007 Antenna & Feeder System
Fault Analysis and Troubleshooting
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2. DMRS: demodulation reference signals
eNodeB LTE V100R007 Antenna & Feeder System
Fault Analysis and Troubleshooting
RSSI: Received Signal Strength Indicator
In LTE, RSSI is reported by baseband to help judge whether there is UL interference.
How to start the task in U2000:
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3. Value range of RSSI can be analyzed in the same way as RTWP.
eNodeB LTE V100R007 Antenna & Feeder System
Fault Analysis and Troubleshooting
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4. Parameters explanation in ADD CELLSIMULOAD
eNodeB LTE V100R007 Antenna & Feeder System
Fault Analysis and Troubleshooting
Configure Index:
Indicates the index of a simulated load configuration. One eNodeB can store a
maximum of 10 simulated load configurations. They are identified by indexes
ranging from 0 to 9 and correspond to RB usage thresholds 10% to 100% at a
step of 10%. For example, the RB usage thresholds for simulated load
configurations 1 and 4 are 20% and 50%, respectively. Alternatively, you can
manually specify the RB usage threshold for a simulated load configuration by
setting the SimuLoadRbThd parameter in MOD SIMULOAD.
PIM can be troubleshot by adjusting the configure index to adjust the load level.
SimuLoad transmission mode:
Indicates the transmission mode adopted by the simulated load configuration. Its
value can be set to TM1, TM2, TM7(TM7), and TM8. For an FDD cell, TM2 is set;
for beamforming in TDD cells, the other transmission mode is used.
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5. FFT frequency scan can be taken as an assisted way for PIM determination. There is no
eNodeB LTE V100R007 Antenna & Feeder System
Fault Analysis and Troubleshooting
abnormal frequency scan result only belong to PIM, because some other interference
source also will cause the same abnormal frequency scan result as PIM interference.
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6. How to start the task in Web LMT:
eNodeB LTE V100R007 Antenna & Feeder System
Fault Analysis and Troubleshooting
Scan mode:
High-resolution Online Frequency: An online carrier-level scan. Signals in specified
channels are scanned for all established cells on a carrier of a specified radio access
technology (RAT).
Broadband Online Frequency: An online channel-level scan. Signals in specified channels
are scanned for all established cells.
Broadband Offline Frequency: An offline channel-level scan. Signals in specified
channels within the bandwidth of the duplexer are scanned.
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7. Origination of narrow-band interference include:
eNodeB LTE V100R007 Antenna & Feeder System
Fault Analysis and Troubleshooting
Uplink signals from narrow-band system, e.g, GSM system
PIM interference caused by narrow-band system
Other interference source, like the single tone signals generated by some device.
When channel isn’t configured, BBU itself will generate single tone signal, which isn’t
interference, as the rightest spike in the figure.
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8. Origination of broad-band interference include:
eNodeB LTE V100R007 Antenna & Feeder System
Fault Analysis and Troubleshooting
Repeater interference
barrage jamming
PIM interference
Other broad-band interference signals
Interference caused by repeater is a kind of common broadband interference. It will cause
the power of the whole band rising. As below figure shows:
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Interference caused by repeater in
indoor coverage scenario

9. Interference detection test is a kind of Huawei antenna & feeder system self test. It can be
eNodeB LTE V100R007 Antenna & Feeder System
Fault Analysis and Troubleshooting
used during site deployment as engineering acceptance.
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10. The antenna channel must be in TX/RX mode, and the RF module transmits two signals with 20 W.
The frequencies of the two signals are test frequency f1 and test frequency f2.
eNodeB LTE V100R007 Antenna & Feeder System
Fault Analysis and Troubleshooting
The frequencies of the two signals are test frequency f1 and test frequency f2.
f1 and f2 can be determined in the following ways:
If f1 and f2 are set manually, it is recommended that f1 and f2 be set as the highest and
lowest frequencies of the transmit frequency band allocated by the operator.
If they are not set manually, the system will choose two frequencies for them according to
the capacity of the RF module.
Either way should enable the generated 3-order, 5-order, 7-order and higher order IMPs within the
RX band allocated by the operator. The detection is started based on f1, f2, and the thresholds for
the IMPs. The thresholds can be set according to the requirements for inter-modulation.
2-Tone Measurement
Two signals with the power of 20 W are transmitted from the channel of a specified antenna on
frequencies f1 and f2. Check whether the level of PIMs within the RX band meets the requirement
of intermodulation suppression.
Duration: Detection on each antenna port takes 95 seconds.
Sweep Measurement
The principle of this method is the same with 2-tone measurement, but multiple pairs of frequencies
are used. Assume that the start test frequency (f1) is the lowest and the end test frequency (f2) is
highest of the test bandwidth. Frequencies are selected as follows:
Step1: fix f1, the paired frequencies are: f1, f1+∆f; f1, f1+2∆f; f1, f1+3∆f; …; f1, f1+n∆f.
Step2: fix f2, the paired frequencies are: f2-∆f, f2; f2-2∆f, f2; f2-3∆f, f2; …; f2-n∆f, f2.
Duration: It depends on the detection bandwidth and ∆f. For example, if the maximum
instantaneous bandwidth (IBW) is 35 MHz and ∆f is 0.5 MHz, the duration is about 20 minutes.
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11. Service-based IM detection takes samples of six periods, which alternate between
eNodeB LTE V100R007 Antenna & Feeder System
Fault Analysis and Troubleshooting
transmitting simulated load status and non-transmitting simulated load status.
Totally there are 3 groups of test. Each group is composed of one simulated load status
and one non-simulated status, between which wait 3 seconds until the transmit power of
RF modules decreases to a stable value.
Delta threshold (parameter “Delta threshold” in MML) indicates the difference of the
RTWP between full power and no power during the test in UMTS and LTE modes. If the
difference is greater than this threshold, IM interference exists.
Service rate threshold (parameter “Duty threshold” in MML) Indicates the threshold of the
current transmit power to the maximum transmit power for starting an online IM
interference test. For RF module that works in UMTS or LTE mode, when the ratio of the
current transmit power to the maximum transmit power in a cell exceeds this threshold, a
failure message is returned, if the online IM interference test is started on.
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12. How to start on U2000:
eNodeB LTE V100R007 Antenna & Feeder System
Fault Analysis and Troubleshooting
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13. How to start monitoring interface:
64eNodeB LTE V100R007 Antenna & Feeder System Fault Analysis
and Troubleshooting
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14. DTP test is used after PIM interference is confirmed. This test can help to determine
eNodeB LTE V100R007 Antenna & Feeder System
Fault Analysis and Troubleshooting
whether the faulty connection is on or below the antenna tower, to eliminates the need
for unnecessary maintenance on the tower and therefore reduces the maintenance cost.
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15. FDR (Frequency Domain Reflectometer) is originally an application in military, nowadays, it
eNodeB LTE V100R007 Antenna & Feeder System
Fault Analysis and Troubleshooting
is applied to the filed of commercial communication test.
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16. How to start DTP test on Web LMT
eNodeB LTE V100R007 Antenna & Feeder System
Fault Analysis and Troubleshooting
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Step 2. DTP test task selection
Step 3. Parameter setting
Step 1. enter Web LMT monitor interface