I just started doing base station maintenance for China Mobile and I almost don’t know anything about it. Could anyone who knows please tell me carefully~~ The more detailed the better~ There will be

I just started doing base station maintenance for China Mobile and I almost don’t know anything about it. Could anyone who knows please tell me carefully~~ The more detailed the better~ There will be reward points.

If you work for China Mobile, you must undergo training from a municipal company and take an exam. Written test scores, upper level scores. If you are doing it for a third party: See for details: 5 Problems and Solutions During Base Station Maintenance

5.1 Types of Problems Occurring during Base Station Maintenance

General Faults can be divided into the following categories: base station hardware faults, base station software faults, AC-induced faults (short circuit, open circuit, replacement of switches, fuses, changes to indoor and outdoor wiring, restoration of power supply after power outage, etc.), DC faults (replacement of switches, fuses, etc.) wire, replace the rectifier module, replace the monitoring module, modify the switching power supply parameters, etc.), battery failure, air conditioning failure, base station transmission troubleshooting, base station power environment monitoring equipment failure, etc.

5.2 Causes and Solutions of Problems During Base Station Maintenance

When the base station fails and is out of service: first consider the power supply, transmission and temperature issues, and check the AC and DC of the base station through monitoring Voltage (the last data uploaded before decommissioning), there are three factors that affect the normal operation of power equipment: the impact of seasonal changes on the power supply, the impact of human factors on the power supply, and the aging of the equipment.

5.2.1 Failures caused by power supply problems

(1) The impact of seasonal changes on power supply:

Due to more rain and fog in winter, outdoor lines The insulation is reduced, so the increase in heating appliances is a period when power failures are common. In addition, the humidity in midsummer is high and the insulation is relatively low, so the increase in refrigeration appliances is a period when power failures are common. In order to prevent major accidents, safe electricity inspections should be strengthened, focusing on mains power introduction lines, power transformation and distribution equipment, and air-conditioning units.

(2) The impact of human factors on power supply:

For rural public transformers connected to 380V or 220V power supply, major faults caused by incorrect fire and neutral wires should be prevented.

(3) Equipment aging:

Such faults are mostly caused by the aging of cable lines.

(220v base station indoor battery)

5.2.2 Failures caused by transmission problems

Transmission failures: Transmission failures are relatively complex and difficult to handle. Faults involve many aspects, so correctly determining the location of the fault is a key issue in shortening the duration of the fault. Therefore, segmented troubleshooting and accurate positioning are the primary methods for handling transmission faults. We will use the optical transceiver as an intermediary point to first eliminate the fault of the outside line in the computer room, use a transmission tester to test the optical cable, and confirm that the outside line is normal; at the same time, we will check the internal lines and equipment in the computer room (from the ODF box to the MDF part of the computer room outside) to determine the location of the fault. so that it can be processed in a timely manner.

The physical connections of the A interface between the Mobile Services Switching Center (MSC) and the Base Station Controller (BSC) and the ABIS interface between the Base Station Controller (BSC) and the Base Transceiver Station (BTS) are It is implemented using standard 2.048MB/S PCM digital transmission. If there is a PCM synchronization loss alarm during transmission, first check the PCM connections of the COM3 and COM7 ports on the top of the cabling rack. Because a rack has two PCM ports, there are relevant definitions in the PCM settings of the base station installation database (IDB). If the port used in the definition is inconsistent with the actual connection, an alarm will occur during transmission, and the TRX data will not be loaded. This is a problem we often encounter during projects. This alarm may also occur if the transmission quality between the BSC and the base station is poor, such as code slippage, bit errors, or excessive interference.

Sometimes transmission alarms are also related to the base station hardware. Since the PCM line is ultimately connected to the G703 interface of the DXU, the port may be damaged during the operation of the base station, causing remote alarms in transmission. In addition, the 75 ohm 2M line from the base station to the transmission equipment is prone to problems. In addition, the stable operation of each component of the base station is inseparable from a stable clock signal. The clock signal of the base station is extracted from PCM transmission, so the clock signal must also be ensured. of stability.

During daily maintenance, all or part of the carrier frequency of the base station is often unstable, sometimes out of service and sometimes working. The BSC side-to-CF test result is BTS COMMUNICATION NOT POSSIBLE or CF LOAD FAILED. Most of these failures are caused by unstable transmission, bit errors, and slippage. When transmission errors accumulate to a certain level, the BSC cannot control the base station and load data. At this time, the IDB data can be reloaded through OMT in local mode, and it can return to normal after reset.

(Indoor transmission line frame)

5.2.3 Failures caused by equipment problems

Equipment failure: For equipment failure, first of all, the equipment failure should be handled according to the conditions in the computer room. Make judgments based on the equipment running status indicator lights and alarms from the supervision center network management. Because the faulty equipment itself does not necessarily have a problem, it is a problem with other corresponding ancillary equipment (signal interruption lines, interfaces, etc.), so be proficient in mastering each The meaning of each alarm and the corresponding handling method are the first conditions for handling equipment faults. Including failures caused by hardware equipment and failures caused by software equipment.

The software in the base station system is to direct and manage the various components of the base station to operate in an orderly and normal manner. If the base station IDB data does not match the base station conditions, the base station will definitely not work properly. Failures include diversity reception alarms or standing wave ratio alarms.

5.3 Diversity Technology - Overview

The fading effect is one of the main factors affecting the quality of wireless communication. The depth of fast fading can reach 30~40dB. If you want to increase the transmit power, increase the size and height of the antenna, etc. to overcome this deep fading, it is unrealistic and will cause interference to other radio stations. The diversity method is used to receive signals carrying the same message that have little correlation with each other on several branches, and then combine and output the signals of each branch through combining technology, which can greatly reduce the risk of deep fading at the receiving terminal. Probability. Correspondingly, diversity reception technology needs to be used to mitigate the impact of fading in order to obtain diversity gain and improve reception sensitivity. This technology has been widely used in accompanying channels including mobile communications, shortwave communications, etc. In the second and third generation mobile communication systems, these diversity reception technologies have been widely used.

5.3.1 Diversity technology - research significance

Diversity reception technology is a major anti-fading technology. It can greatly improve the reliability of multipath fading channel transmission. In practice, In mobile communication systems, mobile stations often work in urban buildings or other complex geographical environments, and the speed and direction of movement are arbitrary. After the transmitted signal passes through the propagation path of reflection, scattering, etc., the signal arriving at the receiving end is often the superposition of multiple signals with different amplitudes and phases, causing the received signal amplitude to fluctuate randomly, forming multipath fading. Signal components in different paths have different propagation delays, phases, and amplitudes, and are appended with channel noise. Their superposition will cause the composite signals to cancel or enhance each other, leading to severe fading. This kind of fading will reduce the available useful signal power and increase the impact of interference, causing distortion, waveform broadening, waveform overlap and distortion of the received signal of the receiver, and even causing a large number of errors in the demodulator output of the communication system, making communication completely impossible. . In addition, if the transmitter or receiver is in a mobile state, or the channel environment changes, it will cause the channel characteristics to change randomly over time, and the received signal will have more severe distortion due to the Doppler effect. In actual mobile communications, in addition to multipath fading, there is also shadow fading. When the signal is blocked by tall buildings (such as a mobile station moving in front of a building away from the base station) or undulating terrain, the received signal amplitude will be reduced. In addition, changes in meteorological conditions also affect signal propagation, causing changes in the amplitude and phase of the received signal. These are unique characteristics of mobile channels, which have adverse effects on mobile communications. In order to improve the performance of mobile communication systems, three technologies, diversity, equalization and channel coding, can be used to improve the quality of received signals. They can be used alone or in combination.

5.3.2 Diversity Technology - Basic Principles

According to the principles of signal theory, if copies of the original transmitted signal with other attenuation degrees are provided to the receiver, it will help to correctly receive the signal. judgment. This method of improving the correct decision rate of a received signal by providing multiple copies of the transmitted signal is called diversity. Diversity technology is used to compensate for fading channel losses. It usually takes advantage of the uncorrelated characteristics of independent samples of the same signal in the wireless propagation environment and uses certain signal combining techniques to improve the received signal to resist the adverse effects caused by fading. Space diversity means can overcome spatial selective fading, but the distance between diversity receivers must meet the basic condition of being greater than 3 times the wavelength. The basic principle of diversity is to receive multiple copies carrying the same information through multiple channels (time, frequency or space). Due to the different transmission characteristics of multiple channels, the fading of multiple copies of the signal will not be the same. The receiver uses the information contained in multiple copies to more accurately recover the original transmitted signal. If diversity technology is not used, under noise-limited conditions, the transmitter must send higher power to ensure normal link connection when the channel condition is poor. In a mobile wireless environment, since the battery capacity of handheld terminals is very limited, the power available in the reverse link is also very limited. The diversity method can reduce the transmit power, which is very important in mobile communications. Diversity technology includes two aspects: first, decentralized transmission, which enables the receiver to obtain multiple statistically independent fading signals that carry the same information; second, centralized processing, which processes multiple statistically independent fading signals received by the receiver. Combined to reduce the effects of fading. Therefore, the most important condition to obtain the diversity effect is that the signals should be "uncorrelated".

5.3.3 Diversity Technology - Technology Classification

To sum up, the essence of transmit diversity technology can be considered to involve the combination of space, time, frequency, phase and coding resources. A multi-antenna technology. According to the different resources involved, it can be divided into the following major categories:

Space diversity

We know that in mobile communications, a slight change in space may lead to larger fields. Strong changes. When two receiving channels are used, the fading effects they suffer are uncorrelated, and the possibility that they are affected by deep fading valley points at the same time is also very small. Therefore, this idea leads to the solution of using two receiving antennas. , independently receive the same signal, and then combine the output, the degree of fading can be greatly reduced, this is space diversity. Spatial diversity is achieved by utilizing random changes in field strength with space. The greater the spatial distance, the greater the difference in multipath propagation, and the smaller the correlation of the received field strength. The correlation mentioned here is a statistical term that indicates the degree of similarity between signals, so the necessary spatial distance must be determined. After testing and statistics, CCIR recommends that in order to obtain satisfactory diversity effects, the distance between the two antennas of the mobile unit should be greater than 0.6 wavelengths, that is, dgt; 0.61, and it is best to choose it near an odd multiple of l/4. If the antenna spacing is reduced, even as small as 1/4, a very good diversity effect can be achieved. Space diversity is divided into two systems: space diversity transmission and space diversity reception. Space diversity reception is to set up several antennas at different vertical heights in space to receive microwave signals from a transmitting antenna at the same time, and then synthesize or select one of the strong signals. This method is called space diversity reception. The distance between the receiving antennas should be greater than half the wavelength to ensure that the fading characteristics of the output signals of the receiving antennas are independent of each other. That is to say, when the output signal of a certain receiving antenna is very low, the output of other receiving antennas will be The phenomenon of low amplitude does not necessarily occur at the same moment. The corresponding combining circuit selects the channel with larger signal amplitude and the best signal-to-noise ratio to obtain a total receiving antenna output signal. This reduces the impact of channel fading and improves transmission reliability. The advantage of space diversity reception is high diversity gain, but the disadvantage is that a separate receiving antenna is required.

There are two types of variations of space diversity: . Polarization diversity: It uses the signals emitted by two antennas with orthogonal polarization directions at the same place to show unrelated fading characteristics for diversity reception, that is, installing them on the transmitter and receiver antennas. Horizontally and vertically polarized antennas can perform polarization diversity on the obtained two signals with unrelated fading characteristics. Advantages: Compact structure, saving space; Disadvantages: Since the transmission power is distributed to two antennas, there is a 3dB loss. .Angle diversity: Due to differences in terrain, landforms, and receiving environments, different path signals arriving at the receiving end may come from different directions. In this way, directional antennas can be used at the receiving end to point to different arrival directions. The multipath signals received by each directional antenna are uncorrelated.

Frequency Diversity

Frequency diversity is to use two or more microwave frequencies with a certain frequency interval to send and receive the same information at the same time, and then synthesize or select to use the information located in different frequency bands. The statistically uncorrelated characteristics of the signal after passing through the fading channel, that is, the difference in the fading statistical characteristics of different frequency bands, are used to achieve the function of resisting frequency selective fading. During implementation, the information to be sent can be separately modulated and transmitted on frequency-irrelevant carriers. The so-called frequency-irrelevant carriers refer to when the spacing between different carriers is greater than the frequency coherence interval, that is, the spacing of carrier frequencies should satisfy: Diversity technology In the formula: △f is the carrier frequency spacing, Bc is the relevant bandwidth, and △Tm is the maximum multipath delay difference. When two microwave frequencies are used, it is called double frequency diversity. Like the space diversity system, the frequency diversity system requires that the correlation of the two diversity received signals is small (that is, the frequency correlation is small). Only in this way will the two microwave frequencies not occur at the same time on a given route. Fading, and obtain better frequency diversity improvement effect. Within a certain range, the two microwave frequencies f1 and f2 are different, that is, the larger the frequency interval △ f=f2-f1, the smaller the fading correlation between the two different frequency signals. Compared with space diversity, the advantage of frequency diversity is that it can reduce the number of receiving antennas and corresponding equipment at the receiving end. The disadvantage is that it takes up more frequency band resources. Therefore, it is generally called in-band (in-band) diversity, and Multiple transmitters may be required at the transmitting end.

Time diversity

Time diversity is to retransmit the same signal multiple times in different time intervals. As long as the time interval between each transmission is large enough, the fading that occurs when each transmission is degraded will be Statistics are independent of each other. Time diversity takes advantage of the statistically uncorrelated characteristics of these fadings, that is, the difference in statistical characteristics of fading over time, to achieve the function of resisting time-selective fading. In order to ensure that the repeatedly transmitted digital signal has independent fading characteristics, the time interval of repeated transmission should meet: Diversity technology fm is the fading frequency, V is the movement speed of the mobile station, and the last parameter is the operating wavelength. If the mobile station is stationary, the moving speed v=0, and the time interval required for repeated transmission is infinite. This shows that time diversity is ineffective for stationary mobile stations. Compared with space diversity, the advantage of time diversity is that it reduces the number of receiving antennas and corresponding equipment. The disadvantage is that occupying time slot resources increases overhead and reduces transmission efficiency.

Polarization diversity

In a mobile environment, the signals emitted by two antennas at the same location with orthogonal polarization directions show uncorrelated fading characteristics. Taking advantage of this feature, by installing vertically polarized antennas and horizontally polarized antennas at the transceiver and receiver ends respectively, you can obtain two signals with uncorrelated fading characteristics. The so-called directional dual-polarization antenna integrates two receiving antennas of vertical polarization and horizontal polarization into one physical entity, and achieves the effect of space diversity reception through polarization diversity reception. Therefore, polarization diversity is actually a special form of space diversity. In this case, there are only 2 diversity branches. The advantage of this method is that it only requires one antenna, is compact in structure, and saves space. The disadvantage is that its diversity reception effect is lower than that of the space diversity reception antenna, and since the transmit power needs to be distributed to two antennas, it will cause a 3dB Signal power loss. Diversity gain depends on the quality of the uncorrelated characteristics between antennas, and spatial diversity is achieved through separation between antenna positions in the horizontal or vertical direction.

And if a cross-polarized antenna is used, this isolation requirement also needs to be met. For dual-polarized antennas with polarization diversity, the orthogonality of the two cross-polarized radiation sources in the antenna is the main factor that determines the uplink diversity gain of microwave signals. This diversity gain depends on whether the two cross-polarized radiation sources in a dual-polarized antenna provide the same signal field strength within the same coverage area. The two cross-polarized radiation sources are required to have good orthogonal characteristics and maintain good horizontal tracking characteristics within the entire 120" sector and switching overlap area, replacing the coverage effect achieved by the space diversity antenna. In order to obtain good The coverage effect requires the antenna to have high cross-polarization resolution within the entire sector, determined by the orthogonal characteristics of the dual-polarization antenna within the entire sector, that is, the uncorrelatedness of the signals at the two diversity receiving antenna ports. In order to obtain better signal uncorrelated characteristics at the two diversity receiving ports of the dual-polarized antenna, the isolation between the two ports is usually required to be above 30dB.

The directional base station in the GSM900MHz cellular system basically adopts a three-cell system, that is, a base station is evenly divided into three cells, each cell is 120 degrees, and the center of the first cell should face at least two true north. Antennas with the same direction are used to achieve diversity reception (one is also used for transmission), so a three-cell directional base station should have at least six antennas for transmitting and receiving.

The distance between the two antennas exceeds 1. In the case of 4 meters, diversity reception can be used to obtain a gain of about 3dB. At the same time, the base station can judge whether its receiving system is normal by comparing the two-way signals. If the TRU detects that the strength of the two-way received signals is very different, the base station will A diversity reception loss alarm may occur. The diversity reception loss alarm may be caused by a fault in the radio frequency connection from the TRU, CDU, or CDU to the TRU, or the antenna feeder. For directional base stations, the most common cause is the antenna. Wrong connection of feeder lines. Because the feeder lines are connected to the indoor rack and the tower top antenna respectively, if the installer is not careful, it is easy for the rack and antenna to be connected incorrectly. The directions will be inconsistent, and the antenna with the wrong direction will not be able to receive the signal from the mobile phone in the cell or the received signal will be very weak, causing the base station to generate a diversity reception loss alarm. At the same time, the base station will also be accompanied by higher congestion and call drops. Alarms caused by these reasons always appear in two or three cells at the same time. For this type of alarm, the first method is to check each antenna feeder in turn. The advantage of this method is that fault location is rapid and accurate, but the disadvantage is that it must rely on high-altitude workers. Cooperate; the second method is to switch the antenna feeders indoors in sequence, and use OMT software to check the antenna alarms. If there are such alarms in the first and second cells at the same time, you can use OMT to see which antenna in the first and second cells appears red. Alarm, use Site Master to measure, you can check whether there is a problem in the front 1/2 feeder to the antenna section of the CDU. When the standing wave ratio is greater than 1.4, find the fault point through fault location, and judge the fault point based on the distance. Generally, it is less than 6 meters. For indoor connector problems, mainly check the cabinet top connector, indoor pigtail and 7/8 feeder connector, and the RF connection from CDU to TRU. Mainly check whether the interface is loose and whether the connection is correct. You can also solve the problem by exchanging the two alarm antennas. Problem: After resetting the TRU or DXU, the diversity reception alarm will disappear. This does not mean that the fault is solved. It will appear again after half an hour or a day or two. The diversity reception alarm is not prompted until the alarm counter reaches the threshold value, so the cause must be found and solved completely.

The third method is through signal testing. For base stations that use transceiver antennas, use TEMS or other instruments to measure the cell in sequence at the center point of a cell about one kilometer away from the base station. The reception levels of all carrier frequencies (the frequency hopping of this cell should be turned off), and based on the measurement results, determine whether the antenna feeder is connected incorrectly. If the cell uses only one transmitting antenna, you can change the transmission to another antenna after testing the antenna.

(If only one RX antenna has an alarm, and the fault point may be the CDU RX port, the RX antenna has an excessive standing wave ratio (measured with SATE MASTER), or the RX cable in the community is incorrectly connected, such faults will occur. The RU unit alarm is generally RX 2A1 or 2A2.

5.4 Standing Wave Ratio – SWR

Standing Wave Ratio is called Voltage Standing Wave Ratio, also known as VSWR and SWR, which is the English Voltage Standing. The abbreviation of Wave Ratio. Where the incident wave and the reflected wave have the same phase, the voltage amplitudes add up to the maximum voltage amplitude Vmax, forming a wave antinode; where the incident wave and the reflected wave have opposite phases, the voltage amplitudes subtract to the minimum voltage amplitude Vmin. A node is formed. The amplitude value at other points is between the antinode and the node. This synthetic wave is called a standing wave. The ratio of the standing wave is the sound pressure amplitude Vmax at the antinode and the node. The ratio of the sound pressure Vmin amplitude. In the standing wave tube method, the sound reflection coefficient and sound absorption coefficient of the sound-absorbing material can be obtained by measuring the standing wave ratio. In radio communications, the impedance of the antenna and the feeder does not match or If the impedance of the antenna does not match the transmitter, the high-frequency energy will be reflected back and merge with the forward interference to form a standing wave. In order to characterize and measure the standing wave characteristics in the antenna system, that is, the forward wave and the forward wave in the antenna. In the case of reflected waves, people have established the concept of "standing wave ratio", SWR=R/r=(1 K)/(1-K) Reflection coefficient K=(R-r)/(R r) (K is a negative value When the two impedance values ??are the same, the reflection coefficient K is equal to 0 and the standing wave ratio is 1. This is an ideal situation. In fact, there is always reflection, so the standing wave ratio is always greater than 1. Special attention must be paid to the voltage standing wave ratio to meet certain requirements, because the frequency range is very wide when used in broadband, and the standing wave ratio will increase with the frequency range. The impedance should be matched as much as possible within a wide range according to the frequency.

5.4.1 The meaning of the standing wave ratio:

The standing wave ratio is a numerical value used to represent the antenna and the radio wave. Whether the transmitting station matches. If the SWR value is equal to 1, it means that the radio waves transmitted to the antenna are all transmitted without any reflection. This is the most ideal situation. If the SWR value is greater than 1, it means that some of the radio waves are reflected back. Eventually, it turns into heat, causing the feeder to heat up. The reflected wave can also generate a very high voltage at the output port of the transmitter, which may damage the transmitter.

Standing Wave Ratio (VSWR) detection loss alarm: TRU. The VSWR detection loss alarm is a relatively common fault. Each TRU needs to be connected to the CDU through two radio frequency lines, PFWD and PREFL, to detect the forward output power and reverse power of the CDU. If the reverse power is too large, it means that the reverse power is too high. The standing wave ratio of this antenna is too large or there is a problem with the CDU, which will also affect the normal operation of the transmitter. At this time, the TRU will automatically shut down the transmitter and generate an antenna standing wave ratio (ANT VSWR) alarm (CF2A8) and corresponding The TX ANT will appear (TX1B4). The TRU also needs to perform a loop test on the two radio frequency lines PFWD or PREFL. If the loop fails, a VSWR/POWER detection loss alarm (CF2A15) will be generated.

One end of the two radio frequency lines PFWD and PREFL is connected to the front panel of the CDU, the other end is connected to the back panel of the TRU, and connected to the TRU through the radio frequency head. Regarding this alarm (CF2A15), firstly, the connector on the front panel of the CDU may be loose, but more likely, the backplane of the TRU is not in good contact. This is often caused by the construction or maintenance personnel being careless when installing the TRU, and the two radio frequency heads are not fully connected. Alignment, causing one of the radio heads to be recessed.

For the TRU, we can disassemble it and take out the radio head; for the back panel, the traditional method is to take out the entire back panel and then process the radio head, but just removing the back panel requires a lot of work. After spending several hours, I came up with a relatively simple method, which is to use a hard steel wire to make a hook and hook out the recessed radio frequency head. In this way, it only takes a few minutes to deal with a fault. It is worth noting that the location of the base station where such an alarm has occurred must be marked, otherwise the alarm is likely to occur again when the TRU is replaced in the future. When inserting the TRU, do not use too much force. Find a good position and insert it slowly. If the force is too heavy, the radio frequency head on the backplane will be recessed, causing data loss.

TRU failure: A general TRU failure is easy to handle, because we can easily use the BSC or OMT terminal to view the TRU alarm code to determine the cause of the failure. For example, if a TX NOT ENABLE fault occurs on the carrier frequency, we can check whether it is a TRU problem or an antenna problem based on the alarm code. But sometimes TRU faults cannot be detected by the base station software itself. For example, I once encountered a TRU whose TX failed to work, but there was no alarm code. I checked that the base station hardware and BSC parameters were correct, and the fault was eliminated after replacing the TRU. Another common TRU fault is high call drops. If a cell usually works normally, but suddenly the call drops are extremely high from a certain day, it is most likely that there is a problem with one of the TRUs in the cell. In this case, the base station itself cannot detect it (invisible fault). We can turn off the frequency hopping of the cell, and then use the TEMS mobile phone to dial and test each carrier frequency. Based on the test results, we can determine the faulty one. TRU.

In addition, many failures are not base station hardware failures, but are caused by incorrect BSC parameter settings. For example, the TRU's TX not enable failure (that is, the transmitter does not work), in addition to the above reasons, may also be caused by the cell being in the Halted state, the cell frequency being undefined, the frequency setting or the power setting being wrong, etc. If a cell configured with three carrier frequencies only defines two frequency points, one carrier frequency must not work. ***The carrier frequency of a transmitting antenna also requires a certain interval. For Hybrid Combiner, the interval must be greater than 400kHz, and for Filter Combiner, the interval must be greater than 600kHz. For example, when we installed a new station, we had a cell that used a Filter type combiner (CDU-D). One of the carrier frequency transmitters was always unable to work. Finally, it was found out that the frequencies used by the cell were 70 and 72. The interval is too small, causing the CU to be unable to tune the carrier frequency to the specified frequency. The output power of the TRU is limited by the parameters BSPWRB, BSPWRT and MAXPWR. If the parameters are set to an even number or greater than 47dBm, the transmitter will not work.

(Outdoor antenna)

5.4.2 Failures caused by various interferences

Interference in the mobile communication system will also affect the normal operation of the base station. Co-channel interference, adjacent-channel interference, intermodulation interference, etc. Nowadays, land cellular mobile communication systems use co-frequency multiplexing technology to improve frequency utilization and increase system capacity, but it also introduces various interferences.

In daily maintenance, unreasonable selection of frequency points for new stations and newly added frequencies for expansion stations will cause the base station to fail to work properly. For such failures, the base station should cooperate with the network optimization and comprehensively consider various factors to select a reasonable frequency point. , eliminate the above interference.