CN1870473B - Passive intermodulation testing method of mobile communication base station system - Google Patents

Abstract

This invention relates to test to the passive intermodulation performance of the communication system, which controls an emitter to emit test signals according to a preset mode, controls a receiver to scan and receive the signals in the test bands and analyze spectrums of the received signals to evaluate the entire passive intermodulation performance of the base station, in which, the original outside interference signals are received at the shut-off state of the emitter to eliminate its influence and measure the performance accurately and the received test bands are computed accurately by the known carrier frequency sphere, intermodulation stages and the received frequency sphere parameters and the test signal receiving quality is increased by scanning the emitted and received continuous waves.

Description

Test method for passive intermodulation performance of mobile communication base station system

technical field

The invention relates to the passive intermodulation performance test of a communication system, in particular to the passive intermodulation performance test of a mobile communication base station system.

Background technique

In wireless communication, various system noises and external interference have a great impact on wireless signals and communication quality. Therefore, in the design and installation process of wireless communication systems, it is necessary to test and evaluate the anti-interference performance of the system, and even in the operation and maintenance process, it is necessary to carry out frequent tests to determine the degree of degradation of system performance due to factors such as component aging and environmental impact. Therefore, corresponding measures are taken for maintenance, so as to achieve the purpose of maintaining the service quality of the wireless communication system. It can be seen that system performance evaluation and monitoring are very important to the normal operation of communication systems, and passive intermodulation is one of the typical wireless system performance indicators.

The so-called passive intermodulation (Passive Inter-Modulation, referred to as "PIM") refers to the additional interference to the system caused by the mutual modulation of multiple carrier signals of different frequencies in the system through the mixing effect of the passive components of the system. In modern communication systems, when carrier signals of multiple frequencies pass through some passive components, intermodulation distortion will occur. For cellular mobile communication systems, passive components include duplexers, feeder cables, towers, lightning arresters, antennas, etc., due to unreliable mechanical connections, materials with hysteresis characteristics, and contaminated contact surfaces , signals of different frequencies are mixed nonlinearly at the junction of the materials, producing passive intermodulation products of different amplitudes. However, if these intermodulation distortion signals fall into the receiving frequency band, the signal-to-noise ratio of the receiving signal will decrease, seriously affecting the capacity and quality of the communication system.

Intermodulation distortion at two frequencies is the most fundamental and ubiquitous problem in modern communication systems. For example, for a wireless transceiver system with two carrier frequencies, multi-order intermodulation distortion will be generated after carrier intermodulation. When two (or more) carrier frequency signals pass through a passive device, due to the above-mentioned various nonlinear factors, it will have a mixing effect on the signals, just like a mixing diode. Assuming these two carrier frequencies are F1 and F2, the modulation may produce second harmonics as 2F1 and 2F2, and the maximum intermodulation products further generated by these frequencies are third-order intermodulation distortion, namely 2F1-F2 and 2F2-F1 . The typical index of the third-order intermodulation product (3rd-order Intermodulation, referred to as "IM3") is -153dBc. The meaning of the so-called IM3 being -153dBc is that when two +43dBm carrier frequency signals are applied to the device under test (Device Under Test, referred to as "DUT") at the same time, the resulting IM3 value is not greater than +43-153=-110dBm.

It can be seen that intermodulation distortion will reduce the performance of the communication system. Excessive intermodulation products in the transmitted signal will interfere with other receivers, especially when the intermodulation products just fall within the frequency range of the receiver, it will cause serious receiver performance. Descent doesn't even work properly. Traditionally, wireless system designers have been concerned with intermodulation testing of active devices. With the development of communication systems and the improvement of system quality, more and more attention has been paid to the measurement of passive intermodulation of devices.

However, testing each individual device cannot ensure that the performance of the entire system can reach the target, especially after the system has been running for a certain period of time, the system cannot be monitored for better maintenance, so if the overall passive interaction of the system Tuning performance test evaluation is an urgent problem to be solved at present.

Especially for the mobile communication base station system, its design, installation and work maintenance are relatively independent in each stage. Before the installation, the performance of each component of the system has been tested to meet a certain standard, but after the installation is completed, especially during the operation and maintenance process, the passive intermodulation performance of the system is often not effectively tested, which brings a certain degree of stability to the system. hidden dangers. Especially after the system has been working for a period of time, the components of the system will continue to age, and the passive intermodulation performance of the base station system may further deteriorate, which will reduce the wireless performance of the base station system and affect the good operation of the system.

At present, the passive intermodulation performance test of the mobile communication base station system is only limited to the individual test of each passive component, and the intermodulation performance of the entire base station system when the components work together is not tested. The existing solution is usually to test the passive intermodulation performance of the duplexer, feeder cable, tower amplifier, lightning arrester, antenna and other components used in the base station system before installation to ensure that the design indicators are met. Once the components are assembled to form an overall base station system, they cannot be tested. However, the performance degradation of passive intermodulation caused by problems such as installation environment or component aging will not be monitored and maintained, seriously affecting the normal operation and maintenance of the base station.

In practical application, the above solution has the following problem: After each component of the base station passes the passive intermodulation performance test, it cannot guarantee that the entire base station system can meet the PIM index after installation.

In fact, due to various factors in the component assembly and coordination process, the passive intermodulation performance of the base station will still be reduced. For example, poor connection between components caused by poor installation during the installation process will equivalently introduce new intermodulation factors; or electromagnetic compatibility problems between different components; or changes in the carrier wave and receiving frequency band settings of the base station, resulting in PIM Changes in the scope of influence; or further degradation of component performance due to different external environments; more commonly, due to aging of components and loose structure after the base station system has been working for a period of time, the performance of passive intermodulation will decline.

All of the above situations cannot be guaranteed by separate testing of components before installation, nor can it be resolved by disassembling components for separate testing. It is only possible to monitor the performance changes of the base station system during daily maintenance by performing passive intermodulation performance testing on the base station system as a whole, which is a technical problem that cannot be solved by existing technologies.

The main reason for this situation is that the existing technical solutions are limited to testing each component individually, and cannot conduct an overall test on the entire base station system.

Contents of the invention

In view of this, the main purpose of the present invention is to provide a method for testing passive intermodulation performance of a mobile communication base station system, so that the base station system can perform overall passive intermodulation performance testing and provide accurate base station system performance evaluation indicators.

In order to achieve the above object, the present invention provides a method for testing passive intermodulation performance of a mobile communication base station system, comprising the following steps

A. The transmitter of the base station system to be tested transmits a test signal according to a preset mode, and the preset mode is a transmission and reception control process set according to actual needs;

B The receiver of the base station system scans and receives in the test frequency band according to the preset mode. The order of modulation; then according to the passive intermodulation order and the transmission frequency range of the carrier, determine the frequency range of the passive intermodulation; finally calculate the frequency range of the passive intermodulation and the base station The intersection of the ranges of the receiving frequency bands of the system is to obtain the range of the test frequency bands;

C evaluates the passive intermodulation performance of the base station system according to the spectrum analysis of the received signal.

Wherein, the step A includes the following sub-steps:

The transmitter described in A1 turns off the transmission;

The transmitter in A2 sequentially transmits at least one test signal;

Described step B comprises following substep:

B1 When the transmitter in A1 turns off the transmission, the receiver scans and receives the original external interference signal in the test frequency band at the same time;

B2 When the transmitter in A2 sequentially transmits at least one test signal, the receiver simultaneously scans and receives received signals corresponding to the test signals in the test frequency band.

In addition, in the method, the step C includes the following sub-steps

C1 removing the original external interference signal from the received signal corresponding to at least one of the test signals received by the receiver in turn to obtain a pure test received signal;

C2 compares the spectrum of the corresponding test signal according to the spectrum analysis of the pure test received signal, and comprehensively evaluates the passive intermodulation performance of the base station system.

In addition, in the method, in the step A2, the test signal is a continuous wave, and the transmitter transmits a frequency sweep signal on one of the carriers, and transmits a fixed frequency signal on other carriers; after traversing the current fixed frequency transmission After the signal, change the fixed-frequency transmission signal to another carrier frequency, and then transmit the sweep signal to one of the carriers again, and so on, until all frequency combinations of the two transmission signals; the above-mentioned transmission signal frequency combination scan can be adjusted according to specific conditions Combined deletions to reduce test time;

In the step B2, the receiver performs synchronous scanning and receiving in the intermodulation frequency band corresponding to the test signal.

In addition, in the method, in the step A, the base station system controls the transmitter to transmit according to the command issued by the test console;

In the step B, the base station system uploads the received signal of the receiver to the test console;

In the step C, the test console completes the analysis of the received signal and the evaluation of the passive intermodulation performance.

In addition, in the method, the test console directly controls the base station system through a near-end control interface, or controls the base station system remotely through a base station controller interface and a mobile communication network for testing.

In addition, in the method, the test console controls the base station system by directly installing test software on the base station system, or loading the test software remotely.

By comparison, it can be found that the main difference between the technical solution of the present invention and the prior art is that the transmitter is controlled to transmit the test signal in a preset mode, and the receiver is controlled to scan and receive in the test frequency band at the same time, and the spectrum analysis is performed on the received signal. Evaluate the passive intermodulation performance of the base station system as a whole;

By receiving the original external interference signal when the transmitter is turned off, the external influence can be removed, and the passive intermodulation product of the system itself can be accurately measured;

Accurately calculate the received test frequency band by known parameters such as carrier frequency range, intermodulation order and receiving frequency range, and improve the quality of test signal reception by scanning transmission and receiving continuous waves;

Efficient testing and accurate evaluation of the base station system can be realized through the control of the base station system by the test console and the analysis of the spectrum strength of the received signal;

Two methods of test control are realized through the local control interface and remote network access, and the solutions of direct installation and remote loading of test software are provided respectively, which is convenient for maintenance personnel to test.

The difference in this technical solution has brought more obvious beneficial effects, that is, based on the overall test scheme of the base station system of the present invention, the overall passive intermodulation performance test can be performed on the base station system after installation or after working for a period of time. The external test instrument does not need to disassemble the parts to test separately, which greatly facilitates the monitoring and maintenance of the base station system;

Since the original external interference is received and removed before the test, the accuracy of the intermodulation interference test of the system itself is greatly improved, the credibility of the system performance evaluation is improved, and the positioning and performance detection of the system passive intermodulation problem also has a great effect;

In addition, the accurate estimation of the intermodulation interference frequency band based on the system parameters also makes the test range clearer and the test efficiency is greatly improved. Similarly, the continuous wave scanning transmission and reception also improves the signal-to-noise ratio of the test signal and enables a comprehensive test system Potential intermodulation interference factors;

Finally, through the provision of two solutions: the near-end control interface, the internal installation test software or the remote control and loading test software, the staff can remotely control the base station tests around the network, which greatly simplifies the work of test and maintenance personnel and greatly facilitates For base station activation, regular maintenance, and fault handling, complex test software can be loaded to the base station remotely for implementation. The analysis function is greatly enhanced, which avoids the transformation of system hardware and saves manpower and material costs for network maintenance.

Description of drawings

Fig. 1 is a schematic diagram of the composition of a mobile communication base station system;

Fig. 2 is a flow chart of passive intermodulation performance testing of a base station system according to an embodiment of the present invention.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings.

The basic principle of the present invention is to control and design the transmitter of the base station through software to transmit a predetermined test signal according to a predetermined pattern, and simultaneously control the receiver to scan the received signal synchronously in the expected test frequency band, so that it can be evaluated from the comparative analysis of the frequency spectrum of the two Performance index of system intermodulation interference. On top of this basic idea, there are some additional technical details that can further improve the accuracy and efficiency of the test, reduce the cost of the test, and facilitate the test operation. Such technical details include: removing the influence of external interference by first receiving the original external interference when the transmitter is turned off; pre-estimating the frequency band where the intermodulation interference is located by the carrier frequency receiving frequency band, etc., and controlling the receiver to receive in this frequency band , improve test efficiency; realize the control of the test console to the base station through the base station near-end control interface or the remote network, and realize the upgrade of the base station system test function through direct installation and remote loading of test software, etc. These technologies facilitate the testing work carried out, reducing the cost of testing.

The technical details of the present invention will be further described below by taking a typical base station system as an example. Figure 1 is a schematic diagram of a typical base station transceiver system with two carrier frequencies. The figure shows the components of the base station system from the control side to the air interface side and their connection sequence.

There are generally two interfaces on the control side of the base station. One of the near-end control interfaces can control the base station through a computer at the near-end of the base station. At the same time, there is an interface connected to the base station controller, through which it is connected to the base station controller, and at the same time connected to the operation and maintenance system of the wireless system through this interface, so that the base station can be remotely controlled on any node of the wireless system. Each cell base station of the entire cellular mobile communication network is connected to the network through a base station controller, and realizes mutual access and communication between each base station. The present invention utilizes the two modes of access control provided by these two interfaces, and the details will be given later.

In the structure of the base station system, there are two transmitters and two receivers corresponding to different carrier channels. The flow direction of the transmission signal is: Transmitter 1 and Transmitter 2 generate transmission signals of different carriers, enter the transmission combiner, synthesize one signal, and then enter the transceiver duplexer. After passing through the feeder, lightning arrester, and tower, it is sent to the antenna for emission. The flow direction of the received signal is: the signal received by the antenna enters the transceiver duplexer through the feeder, the tower amplifier, and the lightning arrester, and the received signal via the transceiver duplexer is divided into two paths through the receiving splitter and enters receiver 1 and receiver 2 respectively. .

As mentioned above, since the transceiver duplexer, feeder cable, lightning arrester, tower amplifier and antenna may produce passive intermodulation products, causing adverse effects on the signal received by the receiver, therefore, every link needs to ensure passive intermodulation The modulation products are small enough, and it is necessary to achieve reliable connection and low passive intermodulation products on the connection interface of different components.

However, the size of the passive intermodulation products of the entire base station is not only related to the above-mentioned components involved, but also related to the installation and operation of the base station system. After the base station system has been used for a period of time, the passive intermodulation products may also increase, requiring regular maintenance and testing. The traditional method is to ensure the performance of each component separately, and carefully construct the connection interface to ensure the passive intermodulation performance of the system. There are certain risks in the passive intermodulation performance guarantee of the entire base station system, and once the base station system will experience unpredictable degradation due to environmental influences and time changes, it is necessary to conduct a convenient overall test on the base station system.

The overall intermodulation interference test scheme of the base station system given by the present invention can solve this problem, so that the base station can support the passive intermodulation product test of the complete base station system, greatly improving the accuracy of the actual passive intermodulation performance measurement of the base station system credibility. In the first embodiment of the present invention, the overall test of the base station system is realized according to the following three main steps:

First, control the transmitter of the base station system to be tested to transmit test signals in a preset mode. The test signal here is a specially designed signal that can make the receiver have a higher signal-to-noise ratio when receiving. The preset mode here is The test signal that needs to be transmitted in each necessary link of the test work, or the switch operation of the transmitter;

At the same time, the receiver controlling the base station system scans and receives in the test frequency band according to the preset mode. The reception of the receiver must correspond to the transmitter. The control of different channels by the machine is realized;

Finally, the passive intermodulation performance of the base station system is evaluated according to the spectrum analysis of the received signal. After the test signal is known, the magnitude of the intermodulation interference can be monitored and evaluated according to the comparison of the corresponding received signal.

The details and principles of the detailed transmission mode, test signal, receiving frequency band, and analysis and evaluation method are not given in the solution of the above-mentioned first embodiment, which will be further clarified in the following embodiments one by one. On the basis of the first embodiment, the second embodiment of the present invention introduces the measurement and removal of the original external interference signal, the transmission and synchronous reception of the test signal, the software implementation of the test system and its console definition, etc.

The preset mode mentioned above is the transmission and reception control process set according to actual needs. The mode adopted in the second embodiment is to first turn off the transmitter to receive the original external interference, and then transmit various test signals according to the order in turn. At the same time, the receiver is controlled to scan and receive these signals and the generated interference synchronously. Correspondingly, in the evaluation, the received signal should be subtracted from the original external interference to obtain a pure test received signal, that is, only the received signal generated by the test signal and its own intermodulation interference signal.

In the second embodiment, the aforementioned steps are all implemented by testing software and controlled by the testing console. The test software is additional software based on the base station system, and the test can be realized without upgrading the hardware, thereby reducing the cost. The functions of the console in each step are as follows: the base station system controls the transmitter to transmit according to the commands issued by the test console; the base station system uploads the received signal of the receiver to the test console; the test console completes the analysis and analysis of the received signal Evaluation of source intermodulation performance. The test console here is the computer background of the test software, which is operated by test maintenance personnel, which greatly facilitates the test.

Referring to the test software and the test console, here is the third embodiment of the present invention. On the basis of the second embodiment, in order to facilitate the maintenance and operation test, the existing control side of the base station system is fully utilized. Two interfaces provide two access methods for different needs, namely, the near-end control interface and the remote control interface. The test console directly controls the base station system through the near-end control interface, or through the base station controller interface and the mobile communication network Test at the remote control base station system.

These two access methods correspond to the internal installation or remote loading of the test software respectively. The test console controls the base station system by directly installing the test software on the base station system or by loading the test software remotely. It can be seen that the two access methods given in the third embodiment, especially the second maintenance method through remote access to the existing mobile network, loading test software and controlling the test, are very suitable for existing mobile network regions The current situation of wide distribution solves the difficulties of maintenance personnel, greatly facilitates maintenance and testing work, and saves labor costs.

In view of this, the efficient base station maintenance operation method will become convenient. For example, the base station is connected to the maintenance network of the wireless system through the interface with the base station controller, and the base station can be remotely controlled on each node of the wireless system. Therefore, the passive intermodulation performance test operation of the base station can be carried out remotely; at the same time, the base station can also implement the near-end control of the base station through the maintenance port of the near-end of the base station. The base station can have built-in test software of the present invention, or load the test software online through the near-end or remote control interface. When it is necessary to test the passive intermodulation performance of the base station system, follow the steps below. The data obtained from the base station test is uploaded to the background computer through the external interface of the base station, and the background computer is used to further analyze the test data to obtain the passive intermodulation performance of the base station system.

Fig. 2 shows the detailed flow of the base station system testing method in the embodiment of the present invention according to these schemes.

In step 201, the maintenance tester accesses the base station to be tested through the near-end control interface or network interface at the near-end or remote console. If the base station does not have test software, the test software needs to be installed or loaded. After the loading is successful, That is to say, it enters the testing stage, issues a command to close the normal work flow of the base station, and enters the testing process.

Then enter step 202, the test console issues an order, the base station system turns off all transmitters, and prepares to receive external interference signals;

Simultaneously in step 203, the test console makes the base station system turn on the receiver to scan and receive the original external interference signal in the pre-estimated test frequency band, and transmit it back to the console, and the console saves it;

Then enter step 204, the console sends commands sequentially according to the preset settings, and the transmitter of the base station system transmits various test signals in sequence, and the frequency and modulation mode of these test signals are all controlled by the commands of the console;

At the same time, in step 205, the receiver of the base station system scans and receives the received signals corresponding to various test signals in the frequency band synchronously, and sends them back to the console. take over.

In step 206, it is judged whether the transmission and reception of all test signals have been completed in the test process, if yes, exit the loop and go to step 207, otherwise return to step 204 to continue transmitting test signals.

In step 207, an evaluation is performed in the background based on the collected received signals. First, remove the original external interference signal from the received signals corresponding to various test signals received by the receiver in sequence to obtain a pure test received signal;

Then in step 208, the background analyzes the spectrum of the pure test received signal and compares the spectrum of the corresponding test signal to comprehensively evaluate the passive intermodulation performance of the base station system.

It is noted that in the above process, there is no mention of how to design the mode of the test signal and how to estimate the range of the receiving frequency band. In fact, these two points are also the key points of the present invention. How to design the test signal to make the receiving signal-to-noise ratio meet the requirements, and how to estimate the range of the accurate receiving frequency band to make the performance test more clear, all of which affect the test efficiency and accuracy. These two issues are elaborated below.

In the fourth embodiment of the present invention, on the basis of the second embodiment, the test frequency range received by the receiver is calculated by the following method: first, according to the number of carriers to be tested in the base station system, determine the order of the passive intermodulation to be tested; then According to the passive intermodulation order and the transmission frequency range of the carrier, the frequency range of the passive intermodulation is determined; finally, the intersection of the frequency range of the passive intermodulation and the receiving frequency range of the base station system is calculated to obtain the range of the test frequency band.

For example, in the base station system of the second generation Global System of Mobile Communication (GSM for short), there are two carrier frequencies of 900MHz and 1800MHz.

In the 900MHz GSM communication system, the third-order intermodulation products generated by the transmitting frequency band will fall into its own receiving frequency band. Therefore, for the third-order intermodulation IM3 to be tested, its frequency range needs to be further calculated.

The frequency of the third-order intermodulation product is FIM3=2F1-F2. According to the typical P-GSM900 frequency range settings: base station transmission frequency 935 ~ 960MHz. So F1 ranges [935, 960], F2 ranges [935, 960]. First calculate the value range of FIM3, which is the frequency range of intermodulation, and then check whether this frequency band overlaps with the receiver frequency band. If so, the intersection is the test frequency band of the receiver we are looking for.

The value range of FIM3 is required, only its minimum value FIM3(min) and maximum value FIM3(max) are required. According to the range of transmission frequency, it is easy to obtain: FIM3(min)=2F1min-F2max=2×935-960=910 ; FIM3(max)=2F1max−F2min=2×960−935=985. Hence the FIM3 range [910, 985].

The base station receiving frequency set in the P-GSM900 frequency range is 890~915MHz. It can be seen that [910, 985] and [890, 915] have intersections, and the intersection is the test frequency band of the receiver is [910, 915].

According to the same method, the fifth-order and other higher-order passive intermodulation products can also be calculated. The fifth-order product signal frequency range falling into the receiving frequency band is: minimum value FIM5 (min) and maximum value FIM5 (max): FIM5 (min) = 3F1min-2F2max = 3 × 935-2 × 960 = 885; FIM5 (max) =3F1max-2×F2min=3×960-2×935=1010. It can be seen that [885, 1010] and [890, 915] of FIM5 also have intersecting parts, that is to say, the receiving frequency range of the fifth-order intermodulation is [885, 915].

Through such calculation, it can be determined whether the intermodulation products of each order fall into the receiving range, so as to determine the test frequency band and receive the intermodulation products of this order.

Another example is the third-generation Wideband Code Division Multiple Access ("WCDMA") base station system, the frequency range of Zone I is: base station transmission frequency 2110MHz ~ 2170MHz, base station reception frequency 1920MHz ~ 1980MHz, Through similar calculations, the third-order intermodulation products of any two transmitted signals will not fall into their own receiving frequency bands. It can be found that the 7th order is the lowest-order product of passive intermodulation through traversal and repeated calculations step by step. Calculation method as above: minimum value FIM7(min) and maximum value FIM7(max): FIM7(min)=4F1min-3F2max=4×2110-3×2170=1930; FIM7(max)=4F1max-3×F2min=4× 2170-3×2110=2350. It can be seen that the FIM7 range [1930, 2110] intersects with the receiving range [1920, 1980], that is to say, the test frequency band received by the FIM7 receiver is [1930, 1980].

In addition, for the design of the test signal and the way of transmitting and receiving, the fourth embodiment of the present invention is realized in the following manner: the test signal generally adopts continuous wave (Continous Wave), which can improve the receiving signal-to-noise ratio, and the transmitter transmits on one of the carrier waves. Sweep frequency signals, transmit fixed frequency signals on other carriers, after traversing the current fixed frequency transmission signals, change the fixed frequency transmission signals to another carrier frequency, and transmit frequency sweep signals to one of the carriers again, and so on until two All frequency combinations of the transmitted signal; the frequency combination scan of the above-mentioned transmitted signal can be deleted according to the specific situation to reduce the test time; this can test in the entire range of intermodulation interference; at the same time, the receiver is in the corresponding test signal Synchronous scanning and receiving are performed in the intermodulation frequency band, so that the interference situation can be known from the mixed degree of the spectrum of the received signal.

The frequency point configuration of the normal operation of the base station system usually does not satisfy the frequency relationship of intermodulation products of each order. Therefore, when the passive intermodulation performance of the base station may have declined, the interference to other receivers cannot be found. The invention obtains the base station system by forcing the base station to transmit an easy-to-detect continuous wave signal, configuring the frequency point of the transceiver signal of the base station to the frequency of the lowest-order product, and scanning the passive intermodulation products in the passive intermodulation interval before and after the base station transmits the signal passive intermodulation performance.

To sum up, according to different operating ranges of transmitting frequency and receiving frequency, the frequency distribution of the lowest order product of passive intermodulation can be calculated. By configuring the frequency and function of the two transmitted signals, the receiver aligns the frequency of the intermodulation product and measures the power of the product, and the passive intermodulation performance of the system can be calculated.

For example, in the base station system of the above-mentioned typical P-GSM900 frequency range, it can be known through calculation that the lowest order intermodulation product is the third order, and the fifth order also falls into the receiving frequency band, which can be configured according to the relationship between the transmitting and receiving frequencies falling into the receiving frequency band Two transmitted signals, for example, fix the frequency of one signal at 935MHz, and scan the frequency of the other transmitted signal. According to the budgeted results, it can be known that the other frequency starts from 955MHz to 960MHz, and its third-order intermodulation product falls with the 935MHz signal. In the receiving frequency band, namely 910~915MHz. The receiving frequency of the receiver is changed synchronously with the scanning frequency of the transmitted signal to obtain the energy of the third-order product in 910-915 MHz, and the passive intermodulation performance is obtained according to the aforementioned method. Assuming that the transmit power is two 43dBm signals and the product is -100dBm, the passive intermodulation performance is -143dBc.

Those skilled in the art can understand that in the above descriptions of the various embodiments of the present invention, the specific parameter settings and specific examples of implementation details used have other different situations in various actual reference environments, but they are all within the scope of the present invention. Within the scope, it does not affect the spirit and scope of the present invention.

Although the present invention has been illustrated and described with reference to certain preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the present invention. The spirit and scope of the invention.

Claims (6)

1. A method for testing passive intermodulation performance of a mobile communication base station system, characterized in that it comprises the following steps A. The transmitter of the base station system to be tested transmits a test signal according to a preset mode, and the preset mode is a transmission and reception control process set according to actual needs; B The receiver of the base station system scans and receives in the test frequency band according to the preset mode. The order of modulation; then according to the passive intermodulation order and the transmission frequency range of the carrier, determine the frequency range of the passive intermodulation; finally calculate the frequency range of the passive intermodulation and the base station The intersection of the ranges of the receiving frequency bands of the system is to obtain the range of the test frequency bands; C evaluates the passive intermodulation performance of the base station system according to the spectrum analysis of the received signal. 2. mobile communication base station system passive intermodulation performance test method according to claim 1, is characterized in that, described step A comprises following sub-steps: The transmitter described in A1 turns off the transmission; The transmitter in A2 sequentially transmits at least one test signal; Described step B comprises following substep: B1 When the transmitter in A1 turns off the transmission, the receiver scans and receives the original external interference signal in the test frequency band at the same time; B2 When the transmitter in A2 sequentially transmits at least one test signal, the receiver simultaneously scans and receives received signals corresponding to the test signals in the test frequency band. 3. mobile communication base station system passive intermodulation performance testing method according to claim 2, is characterized in that, described step C comprises following sub-step C1 removing the original external interference signal from the received signal corresponding to at least one of the test signals received by the receiver in turn to obtain a pure test received signal; C2 compares the spectrum of the corresponding test signal according to the spectrum analysis of the pure test received signal, and comprehensively evaluates the passive intermodulation performance of the base station system. 4. mobile communication base station system passive intermodulation performance testing method according to claim 3, is characterized in that, in described step A, described base station system controls described transmitter to transmit according to the order that test console issues; In the step B, the base station system uploads the received signal of the receiver to the test console; In the step C, the test console completes the analysis of the received signal and the evaluation of the passive intermodulation performance. 5. mobile communication base station system passive intermodulation performance test method according to claim 4, it is characterized in that, described test console directly controls described base station system by near-end control interface, or by base station controller interface and mobile The communication network remotely controls the base station system for testing. 6. mobile communication base station system passive intermodulation performance testing method according to claim 5, is characterized in that, described test console is by directly installing test software on described base station system, or by far-end loading described test software to realize the control of the base station system.

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