JP4520902B2 - Radio base station test apparatus and radio base station test method - Google Patents

Description

  The present invention relates to a radio base station test apparatus and a radio base station test method, and more particularly to a radio base station test apparatus and a radio base station test method in a mobile communication system.

  In operating a mobile communication system, system stability is one of the important factors. In order to operate the system stably, in addition to not generating a failure that causes the system operation to stop, when a failure occurs, it is required to quickly detect and recover from the failure. Therefore, the failure detection circuit of the radio base station and its diagnosis method are extremely important.

  The radio base station is equipped with a transmitter and a receiver. Among these, the failure detection of the transmitter can be realized relatively easily by branching a part of the transmission main signal generated by the transmitter and monitoring it. On the other hand, failure detection of the receiver cannot be realized simply by branching and monitoring a part of the received signal. The reason for this is that the power of the received signal input to the receiver varies from moment to moment depending on the installation environment, the number of connected terminals, etc., so a threshold for determining whether the received power value is normal or abnormal can be determined. This is because it cannot be done. Therefore, in order to detect a failure of the receiver, it is generally realized by inputting some known test signal to the receiver and monitoring the reception state of the receiver.

  Depending on the test signal generation method, the receiver diagnosis method is roughly classified into two methods. One is a method in which a part of an output signal of a transmitter mounted in the same radio base station apparatus is branched and used as a test signal, which is called a loopback test. The other is a system in which a test signal generator for outputting a test signal is mounted in the same radio base station apparatus. However, neither method can be measured remotely and online.

For example, Patent Literature 1 discloses a technique for remotely and online confirming the normality of a radio base station. This is a method for testing a base station device and a network by performing voice communication with a mobile terminal in the base station via a network from a telephone in an operation center connected to the network including the wireless base station device. For example, Patent Document 2 discloses a technique in which a similar test method is developed to a normality confirmation method for a packet data call processing function instead of voice communication.
JP 2000-332679 A JP 2002-271280 A

  In the above two conventional examples, an abnormality in the reception path of the radio base station apparatus can be detected, but there is a problem that it is not possible to quantitatively determine a change in radio characteristics such as reception performance deterioration due to a minor failure. Furthermore, there is a problem that a failure location cannot be specified.

  In order to solve this problem, it is necessary to measure the reception sensitivity of the radio base station apparatus with high accuracy. Also, when measuring reception sensitivity, the influence of external noise from the antenna equipment must be considered. In an installation environment with a lot of external noise, the reception sensitivity measurement may be reported worse than the original reception sensitivity value of the base station. The reason is that external noise input via the antenna is superimposed on the test signal, the signal S / N (Signal To Noise Ratio) of the signal deteriorates, and the reception sensitivity of the base station deteriorates.

  In view of the above, it is an object of the present invention to provide a radio base station test apparatus, a radio base station test apparatus for a radio base station, and a radio base station test method for measuring reception sensitivity with high accuracy. Another object of the present invention is to measure the receiving sensitivity with high accuracy by eliminating the influence of external noise and calibrating the measuring system before measuring the receiving sensitivity. An object of the present invention is to diagnose a receiver and a signal path. An object of the present invention is to specify the cause when, for example, a desired reception sensitivity measurement value is not obtained.

In the present invention, a test terminal called TAT (terminal function unit) is mounted on a radio base station apparatus, and reception sensitivity is measured. TAT is a test terminal having the same call processing function as a general terminal. By having the same call processing function as a general terminal, it is possible to measure reception sensitivity without affecting general services. In order to eliminate measurement errors due to external noise, a high-frequency switch is mounted at the antenna input end. When measuring the reception sensitivity, the switch is switched to cut off between the antenna and the base station receiver so that no external noise is input. Further, the normality of the path between the TAT and the base station receiver is confirmed using the output signal of the transmitter mounted on the base station. Thereby, for example, when a desired reception sensitivity measurement value is not acquired, the cause can be specified.
In order to realize these functions, in the present invention, the reception sensitivity of the base station is measured by the following procedure, but the present invention is not limited to this, and an appropriate procedure may be used.
(1) Normality confirmation of path between TAT and base station receiver (2) Path loss between TAT and base station receiver and calibration of transmitter inside TAT (3) Measurement of reception sensitivity of base station receiver

According to the first solution of the present invention,
A terminal function unit for testing a radio base station, having a transmitter and a receiver of a communication terminal in a radio communication system;
A receiver composed of one or two systems for receiving an uplink signal transmitted from the terminal function unit and the communication terminal;
A transmitter for transmitting a downlink signal to be transmitted to the terminal function unit and the communication terminal;
Switching between connecting or terminating the input end of the receiver to an antenna, and a path switching unit for switching a path of a signal from the transmitter and a signal to the receiver;
A base station controller for controlling the base station,
The base station controller
Receive a test start instruction, according to the instruction, terminate the input end of the receiver by the path switching unit, and connect the desired transmitter or receiver and the terminal function unit,
(1) Receiving sensitivity measurement for adjusting a packet error rate to a predetermined range and obtaining a receiving sensitivity based on the adjusted transmission power of the terminal function unit;
(2) The first received power value of the receiver when the receiver and the transmitter of the terminal function unit are connected, and the transmitter when the transmitter and the receiver of the terminal function unit are connected. The second received power value of the terminal function unit is acquired, the difference between the first received power value and the predetermined first received power expected value, and the second received power value and the predetermined There is provided a radio base station test apparatus for controlling either or both of the measurement path diagnosis for diagnosing a fault of the receiver and the signal path depending on whether the difference from the second received power expected value is within a predetermined range. The

According to the second solution of the present invention,
A terminal function unit for testing a radio base station having a transmitter and a receiver of a communication terminal in a radio communication system, and 1 or 2 for receiving an uplink signal transmitted from the terminal function unit and the communication terminal A receiver configured by a system, a transmitter for transmitting a downlink signal to be transmitted to the terminal function unit and the communication terminal, switching whether the input end of the receiver is connected to an antenna or terminating, and A test method for a radio base station comprising a path switching unit for switching a signal path from the transmitter and a signal to the receiver, and a base station control unit for controlling the base station,
Receive test start instructions,
According to the test start instruction, the input end of the receiver is terminated by the path switching unit, and according to the test start instruction, the desired transmitter or receiver and the terminal function unit are connected,
(1) Receiving sensitivity measurement for adjusting the packet error rate to a predetermined range and obtaining the receiving sensitivity based on the adjusted transmission power of the terminal function unit, (2) When the receiver and the transmitter of the terminal function unit are connected The first received power value of the receiver and the second received power value of the terminal function unit when the transmitter and the receiver of the terminal function unit are connected are obtained and predetermined as the first received power value. Depending on whether the difference between the expected first received power value and the difference between the second received power value and the predetermined second received power expected value is within a predetermined range, respectively. A test method for a radio base station is provided that controls either or both of the measurement path diagnoses for diagnosing signal path faults.

The reception sensitivity measurement is, for example,
The base station controller sets the path switching unit so that the receiver and the transmitter of the terminal function unit are connected;
A terminal function unit establishes a call connection state with a predetermined device via a modem unit, and transmits a packet;
The base station controller determines the packet error rate;
The base station control unit commands the terminal function unit to change the transmission power according to the determined packet error rate;
The terminal function unit changes the transmission power in response to a command from the base station control unit;
The terminal function unit transmits the changed transmission power value to the base station control unit;
The base station control unit receives the transmission power value and stores it in the storage unit;
The base station controller again determines the packet error rate;
The base station control unit determines whether the determined packet error rate is within a predetermined range, and repeats reception and storage of a transmission power value command and a transmission power value to the terminal function unit until it falls within the predetermined range;
The base station controller calculates a reception sensitivity based on a transmission power value when the packet error rate is within a predetermined range;
The base station control unit includes storing the calculated reception sensitivity and / or the test result including the failure determination result based on the reception sensitivity in the storage unit or transmitting it to the maintenance device.

  According to the present invention, it is possible to provide a radio base station test apparatus and a radio base station test method for measuring reception sensitivity with high accuracy. Further, according to the present invention, it is possible to measure the reception sensitivity with high accuracy by eliminating the influence of external noise and calibrating the measurement system before the reception sensitivity measurement. According to the present invention, diagnosis of a receiver and a signal path can be performed. Further, according to the present invention, for example, when a desired received sensitivity measurement value is not obtained, the cause can be specified.

  An embodiment of the present invention will be described below with reference to the drawings, taking as an example a radio base station having a three-sector configuration that includes one transmitter and two receivers per sector and enables diversity reception. explain.

FIG. 1 is a configuration diagram of a radio base station. The radio base station 100 includes three sectors (sector 1 110, sector 2 111, sector 3 112), a test function unit 113, a line interface unit 114, and a base station control unit 115.
The signal processing unit (sector 1) 110 includes a radio signal transmission / reception unit 120 and a modulation / demodulation processing unit 121, to which, for example, a transmission / reception shared 0-system antenna 116 and a reception 1-system antenna 117 are connected. The radio signal transmission / reception unit 120 includes a path switching unit 132 that switches transmission / reception paths, a one-system transmitter 133, and two-system receivers (the 0-system receiver 134 and the 1-system receiver 135). Further, the radio signal transmission / reception unit 120 includes a DUP (duplexer) 130 that separates the downlink radio signal 150 and the uplink radio signal 151, and a BPF (band pass filter) 131 that limits the pass band of the uplink radio signal 151. The number of sectors is not limited to three, and may be one, or an appropriate number of sectors may be provided. Further, the receiver and the transmitter may include an appropriate number of systems.

  The transmitter 133 converts the downlink baseband signal 155 input from the modulator 136 into a downlink radio signal 152. The 0-system receiver 134 receives the uplink radio signal 151 transmitted from the terminal 101 via the DUP 130 (signal 153), and converts it into the uplink baseband signal 156. The first-system receiver 135 receives the uplink radio signal 151 transmitted from the terminal 101 via the BPF 131 (signal 154) and converts it into an uplink baseband signal 157. Note that the configuration of the sector 2 111 and the sector 3 112 may be the same as that of the sector 1 110, and thus the description thereof is omitted.

  The modulation / demodulation processing unit 121 includes a modulator 136 and a demodulator 137, and modulates and demodulates data. The line interface unit 114 is an interface between the radio base station 100 and the network 102. The base station control unit 115 has a monitoring / control function of the radio base station 100. The test function unit 113 includes, for example, a terminal function unit 126 and a test function control unit 127. A specific configuration of the test function unit 113 will be described later.

  The maintenance terminal 103 is connected to the base station control unit 115 via the network 102 and has a function of remotely monitoring and controlling the radio base station 100. The test server 104 is a test server, and a terminal function unit 126 inside the test function unit 113 is connected via the network 102.

  FIG. 2 is a detailed configuration diagram of the path switching unit and the test function unit. 3 to 6 are explanatory diagrams (1) to (4) of the radio signal path. The reception sensitivity measurement according to the embodiment of the present invention will be described with reference to FIGS. 2 illustrates the internal configuration of the sector 1 110, the sector 2 111 and the sector 3 112 may have the same configuration as the sector 1 110, and thus the description thereof is omitted.

  In the present embodiment, a test function unit 113 is installed in the radio base station 100, and a path switching unit 132 is installed in the radio signal transmission / reception unit 120. The path switching unit 132 includes, for example, three CPLs (directional couplers) and six SWs (high frequency switches). The CPL and SW are not limited to this, and may be provided with an appropriate number.

  The CPL 201 (second directional coupler) connects the transmitter 133, the DUP 130 (or the path to the antenna), and the SW 202 (or the path to the test function unit) to each other. In addition, the CPL 204 (first directional coupler) includes SW 205 (0-system receiver or transmitter), SW 203 (route to an antenna or termination unit for termination), and SW 209 (route to a terminal function unit). ) And each other. The CPL 207 connects the SW 208 (system 1 receiver or transmitter), the SW 206 (route to the antenna or termination unit) and the SW 209 (route to the terminal function unit) to each other.

  The CPL 201 extracts a part of the downlink radio signal 221 and outputs it to the test function unit 113. The CPL 204 extracts a part of the downlink radio signal extracted by the CPL 201 and outputs it to the test function unit 113. Further, the CPL 204 couples the uplink test signal transmitted from the test function unit 113 to the 0-system uplink main signal path 227 and outputs it to the 0-system receiver 134. The CPL 207 extracts a part of the downlink radio signal extracted by the CPL 201 and outputs it to the test function unit 113. Also, the CPL 207 couples the uplink test signal transmitted from the test function unit 113 to the 1-system uplink main signal path 232 and outputs it to the 1-system receiver 135.

  The SW 203 switches whether the input terminal of the 0-system receiver 134 is connected to the 0-system antenna 116 via the DUP 130 or terminated (connected to the termination unit). The SW 206 switches whether the input terminal of the 1-system receiver 135 is connected to the 1-system antenna 117 via the BPF 131 or is terminated. The SW 202 switches whether to output a part 221 of the downlink radio signal extracted by the CPL 201 to the test function unit 113, to the 0-system uplink main signal path 227, or to the 1-system main signal path 232. .

  For example, the SW 205 switches whether the CPL 204 is connected to the 0-system receiver 134 or to the transmitter 133. For example, the SW 208 switches whether the CPL 207 is connected to the system 1 receiver 135 or the transmitter 133. For example, the SW 205 outputs the uplink test signal transmitted from the test function unit 113 to the 0-system receiver 134 (signal path 303 in FIG. 4) or outputs the downlink radio signal extracted by the CPL 201 to the test function unit 113. (Signal path 304 in FIG. 5). The SW 208 switches between outputting the uplink test signal transmitted from the test function unit 113 to the first-system receiver 135 or outputting the downlink radio signal extracted by the CPL 201 to the test function unit 113. The SW 209 switches whether the test function unit 113 is connected to the 0-system receiver 134 or the 1-system receiver 135.

  During normal operation (non-test), for example, as shown in FIG. 3, SW 203 is set to the 0-system antenna 116 side and SW 205 is set to the 0-system receiver 134 side. Also, SW 206 is set to the 1-system antenna 117 side, and SW 208 is set to the 1-system receiver 135 side. That is, the 0-system uplink radio signal is input to the demodulator 137 through the signal path 301 and the 1-system uplink signal through the signal path 302.

  The test function unit 113 includes a terminal function unit 126, a test function control unit 127, three switches 210, 211, and 213, and a DUP 212. Note that the number of switches is not limited to this, and an appropriate number may be provided. Further, it may further include an upstream path attenuator 222 and a downstream path attenuator. The terminal function unit 126 is a test terminal having a function equivalent to that of the terminal 101 used by a general user. For example, the terminal function unit 126 includes a transmitter 214 and a receiver 215. The test function control unit 127 has a function of controlling the terminal function unit 126 and setting three switches mounted on the test function unit 113. SW 210 and SW 211 have a function of switching the sector to be tested. Further, the SW 213 switches the path of the downlink radio signal output from the transmitter 133 of the base station between a signal path that passes through the uplink signal path and a signal path that does not pass. The DUP 212 separates the downlink test signal and the uplink test signal.

  FIG. 10 is a configuration diagram of the receiver. For example, the 0-system receiver 134 of the wireless signal transmission / reception unit 120 includes an LNA (low noise amplifier) 601, an ISO (isolator) 602, an AMP (amplifier) 603 that amplifies the received signal with low distortion, A BPF (band-pass filter) 604 that attenuates unnecessary signal components and an AGC-AMP (automatic gain control amplifier) 605 are included. Further, the receiver may have a memory (for example, ROM) that can be read from the base station control unit 115, for example. The AGC-AMP 605 has a function of changing the gain of the amplifier in accordance with the input power in order to make the signal power input to the demodulator 137 constant. The receiver can measure the received power value using the gain value of AGC-AMP 605.

As an example, consider a case where the gain of the AGC-AMP 605 is closed-loop controlled so that the signal power input to the demodulator 137 is 0 dBm. Among the components constituting the receiver, only the AGC-AMP 605 has a variable gain, and the other components (for example, LNA 601 and AMP 603) have a fixed gain. Therefore, if the total gain value of all components other than AGC-AMP 605 is the receiver fixed gain, the following equation is established.
(Received power) + (Receiver fixed gain) + (AGC-AMP gain) = 0 dBm
That is,
(Received power) =-(Receiver fixed gain)-(AGC-AMP gain)
It is. Since the receiver fixed gain is a known value, it is possible to measure the received power. Note that the 1-system receiver 135 and the receiver 215 of the terminal function unit 126 have the same configuration as that of the 0-system receiver 134. Therefore, the reception power can be measured by the same method.

(Measurement path diagnosis)
FIG. 7 is an explanatory diagram of a sequence when performing measurement path diagnosis. A diagnosis method for the 0-system receiver will be described with reference to FIG. The diagnosis of other receivers can be diagnosed in the same procedure, and the description thereof will be omitted. Also, since Ack for the request usually exists, it is omitted.

  The measurement path diagnosis is started, for example, when a maintenance person inputs a measurement path diagnosis command to the maintenance terminal 103. The measurement path diagnosis execution command includes measurement conditions such as designation of a measurement target base station and designation of a target sector and a target receiver. Here, a description will be given assuming that diagnosis of sector 1 and 0 system of base station 100 is performed. In addition to the input by the maintenance person, for example, according to a predetermined schedule, the measurement path diagnosis may be started at an appropriate timing such as starting measurement at a predetermined time.

  In step 701, the maintenance terminal 103 notifies the base station control unit 115 of the designated radio base station 100 of a diagnosis start instruction including the designated measurement condition. Note that it is also possible to omit the designation of the sector to be measured and the reception system, and to sequentially execute the test for all the receivers of the radio base station 100.

  In step 702, the base station control unit 115 receives the diagnosis start instruction and instructs the test function control unit 127 to turn on the terminal function unit 126 according to the instruction. In step 703, the test function control unit 127 turns on the terminal function unit 126.

  In step 704, the base station control unit 115 instructs the path switching unit 132 and the tester function unit 113 to set a switch (SW setting (2)). In step 705, the switches of the path switching unit 132 and the test function unit 113 are switched so as to pass through the signal path 302 and the signal path 303 in FIG. For example, SW 203 is set on the termination side, and SW 205 and 209 are set on the 0-system receiver side. Further, the SW 210 of the test function unit 113 is set to the sector 1 side. It should be noted that how each SW is set can be determined in advance according to the SW setting instruction. The signal path 302 is a path during normal operation. Therefore, since the 1-system receiver 135 is connected to the 1-system antenna 117, the service is not stopped.

  In step 706, the base station control unit 115 instructs the terminal function unit 126 to transmit a test signal. The transmission instruction includes, for example, setting of transmission power and transmission frequency. The power and frequency may be specified by the maintenance person from the maintenance terminal 103. In step 707, the transmitter 214 of the terminal function unit 126 transmits a test signal. For example, the terminal function unit 126 can execute a ping and transmit a packet to the test server 104. In addition to ping, an appropriate command or application for transmitting a packet may be executed. The transmitted signal is input to the 0-system receiver 134 through the signal path 303 of FIG. The test signal is addressed to the test server 104, for example, and the 0-system receiver 134 and the demodulator 137 can process the test signal in the same manner as a normal reception signal. In step 708, the terminal function unit 126 reports the transmission power (TAT transmission power value) to the base station control unit 132. For example, after transmitting a test signal for a predetermined time or a predetermined amount, the transmission power is reported.

  In step 709, the base station control unit 115 requests the 0-system receiver 134 to report the received power. In step 710, the 0-system receiver 134 measures the received power of the test signal. In step 711, the 0-system receiver 134 reports the measured received power value (base station received power value) to the base station control unit 115. The base station control unit 115 records the reported TAT transmission power value and base station received power value in the RAM 123 at an appropriate timing (hereinafter, the reported value is referred to as a measured value (1)).

  In step 712, the base station control unit 115 instructs the path switching unit 132 and the test machine function unit 113 to set a switch (SW setting (3)). In step 713, the switches of the path switching unit 132 and the test function unit 113 are switched so as to pass the path 304 in FIG. For example, SW 202 is set on the upstream main signal path 227 side, and SW 205 is set on the transmitter 133 side. SW203, SW209, and SW210 are the same as those in FIG. Further, the SW 213 of the test function unit 113 is set to the upstream main signal path side 227 side.

  In step 714, the base station control unit 115 requests the transmitter 133 to report the transmission power of the transmitter 133 (transmission power report request). In step 715, the transmitter 133 reports the transmission power (base station transmission power value) of the transmitter 133 to the base station control unit 115 in response to the transmission power report request. The transmission power value may be a transmission power for a predetermined time or an instantaneous value of the transmission power may be reported.

  In step 716, the base station control unit 115 requests the receiver 215 to report the received power value. In step 717, the received power received by the receiver 215 is measured. In step 718, the received power value (TAT received power value) measured by the receiver 215 is reported to the base station control unit 115. The base station control unit 115 records the reported base station transmission power value and TAT reception power value in the RAM 123 (hereinafter, the reported value is referred to as a measured value (2)).

  In step 719, the base station control unit 115 diagnoses the normality of the path between the terminal function unit 126 to the 0-system receiver 134 using the measurement values (1) and (2) recorded in the RAM 123. This diagnosis is performed according to the following procedure.

  First, the normality of the transmitter 133 in the base station and the transmitter 214 in the terminal function unit 126 is diagnosed using the base station transmission power value and the TAT transmission power value recorded in the RAM 123. The base station control unit 115 compares the base station transmission power value with the transmission setting power of the transmitter 133, and if the difference is within a regulation (predetermined range), it is normal. Diagnose that the machine 133 is abnormal. The transmission set power of the transmitter 133 can be managed by the base station control unit 115, for example. Moreover, you may make it acquire from another appropriate management part and a transmitter.

  The base station control unit 115 compares the TAT transmission power value with the TAT transmission setting power, and diagnoses that the transmitter 214 is abnormal if the difference is within the regulation and when the difference is not within the regulation. Note that the value set in step 706 can be used as the TAT transmission set power. When the transmitter 133 and / or the transmitter 214 are diagnosed as abnormal, the subsequent procedure is not executed, and the base station control unit 115 notifies the maintenance terminal 103 of the abnormal content and ends the test. In the following procedure, it is assumed that the transmitter 133 and the transmitter 214 are normal.

Next, using the base station received power value and the TAT received power value recorded in the RAM 123, the normality of the signal path, the 0-system receiver 134, and the receiver 215 inside the terminal function unit 126 is diagnosed. The expected value of the base station received power value and the expected value of the TAT received power value can be calculated as follows. That is,
(Base station received power expected value) = (TAT transmission power value) − (path loss)
(TAT received power expected value) = (base station transmission power value) − (path loss)
Here, the TAT transmission power value and the base station transmission power value are measured values and are recorded in the RAM 123. Furthermore, since the path loss is a known value (design value), the expected values of the base station received power value and the TAT received power value can be calculated by using these values. However, since there is an error factor in the expected value due to individual variations of parts, a determination threshold is provided, for example, ± 3 dB. If the difference between the expected value and each received power value recorded in the RAM 123 is within ± 3 dB, it is determined to be normal, and if it is ± 3 dB or more, it is determined to be abnormal. Using this determination result, the normality of the signal path 304, the 0-system receiver 134, and the receiver 215 inside the terminal function unit 126 is diagnosed as follows.

FIG. 13 is a flowchart of normality diagnosis. Hereinafter, normality diagnosis of the signal path, the 0-system receiver 134, and the receiver 215 inside the terminal function unit 126 will be described with reference to FIG.
First, the base station control unit 115 performs transmitter diagnosis (S101). Since details are as described above, description thereof is omitted. Next, the base station control unit 115 calculates a base station received power expected value and a TAT received power expected value. For example, the base station control unit 115 reads the TAT transmission power value, the base station transmission power value, and the path loss from the RAM 123, and obtains the base station received power expected value and the TAT received power expected value by the above formulas.

  Next, the base station control unit 115 determines that the difference between the base station received power value reported in step 718 and the base station received power expected value is within a first range (eg, ± 3 dB) (S105, YES). When the difference between the TAT received power value reported in step 711 and the expected TAT received power value is within the second range (eg, ± 3 dB) (S107, YES), the signal paths 303 and 304, the terminal function The unit 126 and the receiver 215 are determined to be normal (S109). This is referred to as Case1.

  Next, the base station controller 115 determines that the difference between the base station received power value and the base station received power expected value is within the first range (S105, YES), and the TAT received power value and the TAT received power expected value are When the difference is out of the second range (S107, NO), it is diagnosed that the receiver 215 of the terminal function unit 126 is abnormal (S111). In this case, since the base station received power value is normal, the signal path 303 (including the common part with the path 304) is normal. Furthermore, from step S101, the transmitter 133 of the base station is also normal. Therefore, it is diagnosed that the receiver 215 of the terminal function unit 126 is abnormal. This is referred to as Case2.

  Next, the base station controller 115 determines that the difference between the base station received power value and the base station received expected value is outside the first range (S105, NO), and the difference between the TAT received power and the TAT received power expected value is When it is within the second range (S113, YES), it is diagnosed that the receiver 134 is abnormal (S115). In this case, the base station received power value is abnormal and the TAT received power value is determined to be normal. In this case, since the TAT reception power value is normal, the signal path 304 (including the common part with the path 303) is normal. Furthermore, from step S101, the transmitter 214 of the terminal function unit 126 is also normal. Therefore, it is diagnosed that the 0-system receiver 134 is abnormal. This is Case 3.

  The base station control unit 115 determines that the difference between the base station received power value and the base station received expected value is outside the first range (S105, NO), and the difference between the TAT received power and the TAT received power expected value is also the second value. This is the case when it is out of range (S113, NO). In this case, the base station control unit 115 can determine that the path is abnormal or that both the receiver 134 and the receiver 215 of the terminal function unit are abnormal. It is also possible to make a more detailed diagnosis as follows.

  The base station control unit 115 determines whether the difference between the base station received power value and its expected value and the difference between the TAT received power value and its expected value are equivalent or nearly equivalent (S117). For example, if the difference between the two is within a predetermined threshold value, it may be determined that they are substantially equivalent. If the two differences are substantially equal (S117, YES), the base station control unit 115 can diagnose that the path loss of the signal path 304 is excessive (S119). This is because when the path loss becomes excessive, the base station received power value and the TAT received power value are both smaller than the expected value by the excess loss. This is referred to as Case4.

  The base station controller 115 determines that the difference between the base station received power value and the base station received expected value and the difference between the TAT received power and the TAT received power expected value are outside the first and second ranges, respectively (S105: NO S113: NO), the difference between the base station received power value and its expected value is not the same as the difference between the TAT received power value and its expected value (S117: NO), and the base station received power value and the TAT received power. This is a case where both values are determined to be lower limit values (S121, YES). In this case, the base station control unit 115 can diagnose the disconnection of the signal path 304 (S123). When the path itself is disconnected, no signal is input to the 0-system receiver 134 and the receiver 215 of the terminal function unit 126, so both the base station received power value and the TAT received power value are This is because the lower limit is reached. The lower limit value can be determined in advance. This is referred to as Case5.

  The base station control unit 115 determines that the difference between the base station received power value and the base station received expected value and the difference between the TAT received power and the TAT received power expected value are outside the first and second ranges, respectively (S105: NO S113: NO), the difference between the base station received power value and its expected value is not the same as the difference between the TAT received power value and the expected value (S117: NO), and the base station received power value and the TAT received power value. However, it is a case where it is judged that neither is a lower limit (S121, NO). In this case, the base station control unit 115 determines that the signal path 304 is normal, and the 0-system receiver 134 and the receiver 215 of the terminal function unit 126 both diagnose abnormalities (S125). This is referred to as Case 6.

  For Cases 4 to 6, for example, even if the difference between the base station received power value and the expected value in step S117 is equal to the difference between the TAT received power value and the expected value, both receivers are abnormal. There can be. Therefore, for example, in the case of Cases 4 to 6, the base station control unit 115 determines that the path is abnormal or both the receiver 134 and the receiver 215 of the terminal function unit are abnormal, and further any of the above Cases 4 to 6 You may make it judge that there is possibility of.

  FIG. 11 is an explanatory diagram of a diagnostic procedure. With reference to FIG. 11, the diagnostic procedure will be described with numerical examples. For example, the determination threshold (first and second ranges) is set to ± 3 dB. Further, for example, assuming that the TAT transmission power value is −30 dBm and the path loss is 40 dBm, the base station reception power expected value is −70 dBm from the above formula. Similarly, for example, assuming that the base station transmission power value is −30 dBm and the path loss is 40 dBm, the expected TAT reception power value is −70 dBm from the above equation. Here, the above two expected values are described as the same value, but may be different values.

  Case 1 is, for example, a case where the base station received power value is −72 dBm, the base station received power expected value is −70 dBm, the TAT received power measurement value is −71 dBm, and the TAT received power expected value is −70 dBm. Since the difference in base station received power is -2 dBm and within the determination threshold, and the difference in TAT received power is -1 dBm and is within the determination threshold, the receivers 134 and 215 and the path are diagnosed as normal.

  Case 2 is, for example, a case where the base station received power value is −72 dBm, the base station received power expected value is −70 dBm, the TAT received power measurement value is −80 dBm, and the TAT received power expected value is −70 dBm. Since the difference in base station received power is −2 dBm, which is within the determination threshold, and the difference in TAT received power is −10 dBm, which is outside the determination threshold, a failure of the receiver 215 is diagnosed.

  Case 3 is, for example, a case where the base station received power value is -85 dBm, the base station received power expected value is -70 dBm, the TAT received power measurement value is -69 dBm, and the TAT received power expected value is -70 dBm. The base station received power difference is −15 dBm which is outside the determination threshold, and the TAT received power difference is 1 dBm and is within the determination threshold.

  In Case 4, the determination threshold is set to ± 3 dBm, the base station received power value is -82 dBm, the base station received power expected value is -70 dBm, the TAT received power measured value is -83 dBm, and the TAT received power expected value is -70 dBm. is there. The difference in base station received power is -12 dBm, which is outside the determination threshold, the difference in TAT received power is -13 dBm, which is outside the determination threshold, and the difference between the base station received power and the TAT received power is the same, so the loss of path 304 Diagnose that is oversized. Note that numerical examples of Cases 5 and 6 are omitted.

  In this way, the normality diagnosis of the receiver is performed. For example, it can be performed before the reception sensitivity measurement, but is not limited thereto, and may be performed after the reception sensitivity measurement. The determination threshold can be set at the start of diagnosis. Further, it is possible to transmit the measurement values (1) and (2) to the maintenance terminal 103 without setting the determination threshold value and display the measured values on the display unit of the maintenance terminal 103 to make the determination. Furthermore, the difference between the measured value and the expected value can be calculated on either the base station control unit side or the maintenance terminal side.

(Proofreading)
FIG. 8 is a sequence diagram for calibrating the measurement system. The calibration of the measurement system will be described with reference to FIG. The following processing may be executed after step 719 described above, or may be executed by receiving a test start instruction for calibrating the measurement system from the maintenance terminal 103.

  In step 720, the base station control unit 115 instructs the path switching unit 132 and the tester function unit 113 to set a switch (SW setting (4)). In step 721, according to the SW setting instruction, for example, the switch of the path switching unit 132 and the test function unit 113 is switched so as to pass the path 303 in FIG.

  In step 722, the base station control unit 115 instructs the terminal function unit 126 to transmit a test signal. For example, designation of transmission level and frequency may be included. For example, here, -70 dBm and the frequency f2 are specified. Note that the level and frequency of the test signal may be designated by the maintenance person from the maintenance terminal 103. In step 723, the transmitter 214 of the terminal function unit 126 transmits a test signal. The transmitted signal is input to the 0-system receiver 134 via the path 303 in FIG. In step 724, the terminal function unit 126 reports transmission power to the base station control unit 132. The base station control unit 115 stores the reported transmission power in the RAM 123.

In step 725, the base station control unit 115 requests the 0-system receiver 134 to report the received power value. In step 726, the 0-system receiver 134 measures the received power according to the report request. In step 727, the 0-system receiver 134 reports the received power measurement value to the base station control unit 115. The base station control unit 115 stores the reported transmission power in the RAM 123.
In step 728, the base station control unit 115 reads the correction value for each receiver from the ROM mounted on the receiver 134. For example, a correction value corresponding to the frequency f2 is read.

  FIG. 12 is a configuration example of a receiver correction table included in the receiver. For example, correction values are stored in advance for each frequency. This correction value indicates, for example, an error between the actual received power value at the receiver and the reported received power value. In FIG. 12, one table is shown for the 0-system and 1-system receivers, but each system receiver may have a correction value for each frequency.

In step 729, the base station control unit 115 performs calibration from the test function unit 113 to the input terminal of the 0-system receiver 134 based on the value reported from the 0-system receiver 134. The calibration method will be described below.
(1) Calculate the received power value at the 0-system receiver end using the following formula (actual power value at the 0-system receiver end) = received power report value + correction value (2) (1) Calibration of transmitter 214 and reception path mounted on terminal function unit 126 based on the calculated value

For example, the transmission power of the terminal function unit 126 is −30 dBm, the report value of the reception power of the 0-system receiver 134 is −72 dBm, the correction value is the frequency f2, the target system is the 0 system, and the receiver correction of FIG. An example in which −0.3 is set from the table will be described. First, the base station control unit 115 calculates the power at the 0-system receiver end.
(Actual power value at 0-system receiver end) = received power + correction value = −72 + (− 0.3)
= -72.3 dBm
From the above equation, the actual received power at the 0-system receiver end is -72.3 dBm.

  Next, the base station control unit 115 calibrates the terminal function unit 126 and the reception system. First, the base station control unit 115 takes the difference between the transmission power of the terminal function unit 126 and the actual reception power at the receiver end. Since the transmission power of the terminal function unit 126 is −30 dBm and the actual power at the 0-system receiver end is −72.3 dBm, the difference between these two values is 42.3 dBm. This is the loss value of the transmitter 214 and signal path of the terminal function unit 126, for example. If the path loss determined in advance and stored in, for example, a memory or the like is 40 dBm, a shift of 2.3 dBm has occurred.

  If the terminal function unit transmits 2.3 dBm (calibration value) high, including the path calibration, at −27.7 dBm, the actual power at the 0-system receiver end is −70 dBm. In this way, the measurement path is calibrated. Further, the base station control unit 115 may store the obtained loss value and / or configuration value in the memory d. Then, the base station control unit 115 may use the stored loss value instead of the path loss value, for example, in the reception sensitivity measurement described later, or specify the transmission power value to be specified at the time of packet transmission start command. It may be increased by the stored calibration value.

(Reception sensitivity measurement)
FIG. 9 is a sequence diagram of reception sensitivity measurement. The following processing may be executed after step 729 described above, or may be executed by receiving a test start instruction for performing reception sensitivity measurement from the maintenance terminal 103.

  In Step 829, the base station control unit 115 sets each SW as shown in FIG. 6, for example. In step 730, the base station control unit 115 instructs the test function control unit 127 to start call connection. In step 731, the test function unit 127 dials up to the test server 104 to establish a call connection state. The connection destination information such as the dial number of the test server 104 can be stored in advance in the appropriate memory in the base station control unit 115 or the test function unit 113. In step 732, the terminal function unit 126 notifies the base station control unit 115 of “TAT-State change notification” including information indicating that the call is connected. The terminal function unit 126 and the base station control unit 115 can transmit and receive data to and from each other via, for example, the test function control unit.

  In step 733, the base station control unit 115 commands the terminal function unit 126 to start packet transmission (packet transmission start command). The packet transmission start command can include, for example, the above-described calibrated power value (eg, −27.7 dBm). In step 734, the terminal function unit 126 that has received the packet transmission start command starts packet transmission to the server. In step 735, the terminal function unit 126 notifies the base station control unit 115 of “TAT-State change notification” including information on the start of packet transmission.

  In Step 736, the base station control unit 115 requests the terminal function unit 126 to report the transmission power of the terminal function unit 126 (transmission power report request). In step 737, the terminal function unit 126 reports the transmission power of the terminal function unit 126 to the base station control unit 155 in response to the transmission output report request. For example, the terminal function unit 126 reports the average value of the transmission power for a predetermined time before or after receiving the transmission power report request. Further, an instantaneous value of transmission power when a transmission power report request is received may be reported. The base station control unit 115 stores the reported transmission power value P1 in the memory.

In step 738, the base station control unit 115 acquires a PER (packet error rate). The PER can be measured as follows, for example. Each sector has a function of requesting to retransmit a packet that cannot be demodulated due to an error when demodulating an uplink signal transmitted from the terminal function unit 126. Accordingly, among the uplink signal packets received by each sector, it is possible to count the number of packets requested to be retransmitted due to an error (hereinafter referred to as the number of error packets) and the number of normally received packets. Each sector counts the number of error packets and the number of normally received packets, and calculates PER from the following equation.
PER [%] = (number of error packets) / (total number of received packets)
The total number of received packets is the sum of the number of error packets and the number of packets received normally.

  For example, the base station control unit 115 can request the sector 1 (for example, the demodulator 137) to report the PER value, and can acquire the PER transmitted in response to the request. Note that the base station control unit 115 may acquire the number of error packets and the number of normally received packets (or the total number of received packets), and obtain PER by the above formula. Further, the base station control unit 115 stores the acquired PER in a memory.

  In Step 739, the base station control unit 115 commands the terminal function unit 126 to change the transmission power according to the PER (transmission power change command). For example, if the measured PER is lower than the predetermined threshold, the transmission power is decreased, and conversely, if the PER is higher than the predetermined threshold, the transmission power is instructed. Note that the transmission power of the terminal function unit 126 may be fixed at the calibration power described above, and the transmission power may be changed by changing the attenuation amount of the uplink attenuator 222.

  In step 740, the terminal function unit 126 changes the transmission power in accordance with a command from the base station control unit 115. In step 741, terminal function section 126 reports the changed transmission power to base station control section 115. In step 742, the base station control unit 115 acquires PER again and stores it in the memory 123.

  In step 743, the base station control unit 115 determines whether PER is within a predetermined threshold range. If the PER is within the predetermined threshold range, the base station control unit 115 proceeds to the process of step 744. On the other hand, if the measured PER is not within the range of the predetermined threshold, the base station control unit 115 returns to the process of step 739 and repeats the processes of steps 739 to 742 and 743 so that the PER is the predetermined threshold. The transmission power of the terminal function unit 126 is adjusted so as to fall within the range.

In step 744, the base station control unit 115 records the reported transmission power value of the terminal function unit 126 in the memory 123 as a reception sensitivity value. Alternatively, the base station control unit 115 may calculate the reception sensitivity from the reported transmission power value of the terminal function unit 126 and the loss values of the terminal function unit 126 to the receiver 134. For example, the base station control unit 115 refers to the RAM 123, reads the reported transmission power value and path loss value of the terminal function unit 126, and calculates the reception sensitivity by the following equation.
Reception sensitivity = (Transmission power value of terminal function part)-(Path loss value)

  The transmission power of the terminal function unit 126 used here is transmission power in which PER is within a predetermined threshold range by repeating the above-described processing, and is stored in, for example, a memory. The path loss value can be fixed to a value that can attenuate the transmission power of the terminal function unit 126 to the reception sensitivity point. That is, a value fixedly determined at the time of device design may be used. Moreover, you may use the loss value (-42.3dBm as an example) calculated | required by the above-mentioned calibration. Since there is a manufacturing variation in the path loss value, the loss value can be measured at the time of manufacturing, and the value can be stored in an appropriate memory. Here, the reception sensitivity point indicates a power value at which reception becomes impossible when the reception power of the base station 100 becomes equal to or lower than the power.

  Further, the base station control unit 115 determines whether or not a receiver failure has occurred based on the reception sensitivity, for example, whether it is larger or smaller than a predetermined threshold, within or outside a predetermined range, and the determination result is determined. It may be stored in a memory.

  In step 745, the base station control unit 115 commands the terminal function unit 126 to stop packet transmission (packet transmission stop command). In step 746, the terminal function unit 126 stops packet transmission according to the packet transmission stop command. In step 747, the terminal function unit 126 notifies the base station control device 115 of “TAT-State change notification” including information indicating that packet transmission has been stopped.

  In step 748, the base station control unit 115 commands the terminal function unit 126 to release the call connection (call connection release command). In step 749, the terminal function unit releases the call connection according to the call connection release command. In step 750, the terminal function unit 126 notifies the base station control unit 115 of “TAT-State change notification” including information on the release of the call connection.

  In step 751, the base station control unit 115 instructs the test function control unit 127 to turn off the power of the terminal function unit 122 (power-off command). In step 752, the test function control unit 127 that has received the power-off command turns off the terminal function unit 126.

  In step 753, the base station control unit 115 instructs the path switching unit 132 and the test machine function unit 113 to set a switch. In step 754, the switches of the path switching unit 132 and the test function unit 113 are switched so as to pass the paths 301 and 302 in FIG. 3 (SW setting (1)). As a result, the normal operation state is restored.

  In step 755, the base station control unit 115 reports the test result to the maintenance terminal 103. The test result can include, for example, a reception sensitivity and / or a determination result based on the reception sensitivity. In step 756, the maintenance terminal 103 receives the test result, displays the received test result and / or stores it in the storage unit, and ends the test.

  This test can also be carried out in three parts: measurement path diagnosis (reception path diagnosis) in FIG. 7, measurement system calibration (reception sensitivity correction) in FIG. 8, and reception sensitivity measurement in FIG. . Further, it may be implemented by a combination of reception sensitivity correction and reception sensitivity measurement, or reception sensitivity measurement and reception path diagnosis. Moreover, you may perform in an appropriate order. For example, when the reception sensitivity is not obtained normally in the reception sensitivity measurement of FIG. 9, the reception path diagnosis of FIG.

  According to the present invention, it is possible to measure the reception sensitivity of a radio base station with high accuracy without being interrupted by service and remotely and online without being affected by external noise. Further, when the desired sensitivity cannot be obtained, a means for identifying the cause can be provided.

  The present invention can be used, for example, in industries related to mobile communication systems and base stations.

FIG. 3 is a block diagram of a radio base station according to an embodiment of the present invention. It is a detailed block diagram of a path switching unit and a test function unit of sector 1 in the present invention. It is explanatory drawing (1) of the radio | wireless signal path | route at the time of performing the 0 system receiving sensitivity measurement of the sector 1 in this invention. It is explanatory drawing (2) of the radio | wireless signal path | route at the time of performing the 0 system receiving sensitivity measurement of the sector 1 in this invention. It is explanatory drawing (3) of the radio | wireless signal path | route at the time of performing the 0 system receiving sensitivity measurement of the sector 1 in this invention. It is explanatory drawing (4) of the radio | wireless signal path | route at the time of performing the receiving sensitivity measurement of 0 system of the sector 1 in this invention. It is explanatory drawing of the sequence at the time of performing the measurement path | route diagnosis in this invention. It is explanatory drawing of the sequence at the time of performing the structure of the measurement system in this invention. It is explanatory drawing of the sequence at the time of performing the reception sensitivity measurement in this invention. It is a block diagram at the time of performing the reception power measurement in this invention. It is explanatory drawing of the receiver diagnosis in this invention. It is an example of the table for receiver correction | amendment in this invention. It is a flowchart of a normality diagnosis.

Explanation of symbols

100 radio base station 102 network 103 maintenance terminal 104 test server 110, 111, 112 sector 113 test function unit 114 line interface unit 115 base station control unit 116, 117 antenna 120 radio signal transmission / reception unit 121 modulation / demodulation processing unit 126 terminal function unit 127 Test function control unit 130 DUP (duplexer)
131 BPF (band pass filter)
132 Path switching unit 133 Transmitter 134, 135 Receiver 136 Modulator 137 Demodulator 201, 204, 207 CPL (directional coupler)
202, 203, 205, 206, 208, 209 switch

Claims (8)

A terminal function unit for testing a radio base station having a first transmitter and a first receiver of a communication terminal in a radio communication system;
A second receiver configured with one or two systems for receiving an uplink signal transmitted from the terminal function unit and the communication terminal;
A second transmitter for transmitting a downlink signal to be transmitted to the terminal function unit and the communication terminal;
A path switching unit for switching whether the input terminal of the second receiver is connected to an antenna or terminating, and a path of a signal from the second transmitter and a signal to the second receiver; ,
A base station controller for controlling the base station,
The base station controller
A test start instruction is received, and according to the instruction, the input end of the second receiver is terminated by the path switching unit, and the desired second transmitter or second receiver and the terminal function unit are connected. And
(1) Receiving sensitivity measurement for adjusting a packet error rate to a predetermined range and obtaining a receiving sensitivity based on the adjusted transmission power of the terminal function unit; and
(2) a first received power value of the second receiver when connecting the first transmitter of the said second receiver terminal function unit, first and the second transmitter of the terminal functional unit A second received power value of the terminal function unit when connected to one receiver, and a difference between the first received power value and a predetermined first received power expected value; Measurement path diagnosis for diagnosing faults in the second receiver and the signal path based on whether or not the difference between the received power value of 2 and the predetermined expected second received power value is within a predetermined range, respectively.
Radio base station to control. The reception sensitivity measurement is
The base station control unit
Connecting the second receiver and the first transmitter of the terminal function unit by the path switching unit;
Adjusting the transmission power from the terminal function unit so that the packet error rate falls within a predetermined range;
Obtaining reception sensitivity based on the transmission power of the terminal function unit after adjustment;
The radio base station according to claim 1, comprising storing the obtained reception sensitivity and / or a test result including a failure determination result based on the reception sensitivity in a storage unit or transmitting to a maintenance device. The measurement path diagnosis includes
The base station control unit
Connecting the second receiver and the first transmitter of the terminal function unit by the path switching unit;
Transmitting a predetermined test signal from the first transmitter of the terminal function unit;
Obtaining a first received power value of the second receiver;
Said by the path switching unit and the second transmitter is connected to a first receiver of the terminal function unit, part of the signal from the second transmitter is received by the first receiver of the terminal functional unit And
Obtaining a second received power value of the terminal function unit;
Determining whether a difference between a first received power value of the second receiver and a predetermined first received power expected value is within a first range or out of the range;
Determining whether a difference between a second received power value of the terminal function unit and a predetermined second received power expected value is within a second range or out of the range;
According combinations of the determination result, normal, the second receiver fault, the terminal functional unit first receiver failure, or the first reception of said the signal paths abnormality or the second receiver terminal function unit The radio base station according to claim 1, comprising determining which of both of the faults of the machine. The measurement path diagnosis includes
The base station control unit
Obtaining a first transmission power value of the terminal function unit when the second receiver and the first transmitter of the terminal function unit are connected;
And obtaining a second transmission power value, said second transmitter when said second transmitter and the first receiver of the terminal function unit is connected,
Subtracting a predetermined path loss value from the first transmission power value of the terminal function unit to obtain a first received power expected value;
Pull the path loss value set in advance from the second transmit power value of the second transmitter, the radio base station according to claim 3, further comprising: determining a second received power expectations. The measurement path diagnosis includes
The base station control unit
The difference between the first received power value and the first received power expected value of the second receiver, and the difference between the second received power value and the second received power expected value of the terminal function unit, if substantially equal, it is determined that the loss excessive signal paths, and / or the second received power value of the second first received power value of the receiver and the terminal functional unit, both predetermined The radio base station according to claim 3, further comprising: determining that the signal path is disconnected if the value is a negative value. The route switching unit
A first directional coupler that connects an antenna or a termination unit for termination, the terminal function unit, and the second receiver or the second transmitter to each other;
A first switch for switching whether the first directional coupler is connected to an antenna or a terminal unit;
A second switch for switching whether to connect the first directional coupler to the second receiver or to the second transmitter;
A second directional coupler that connects the second transmitter, the antenna, and a path to the terminal function unit,
By setting the first switch to the termination side and the second switch to the second receiver side, the second receiver and the first transmitter of the terminal function unit are connected. Let
By setting the first switch to the termination side and setting the second switch to the second transmitter side, the second transmitter and the first receiver of the terminal function unit are connected. The radio base station according to claim 1. The base station controller
Reading the correction value from a storage unit in which a correction value indicating an error between the actual received power value and the reported received power value in the second receiver is stored in advance;
Correcting the acquired first reception power value of the second receiver with the correction value, and / or correcting the first reception power value and the first transmission power value of the terminal function unit; And correcting the transmission power value instructing the terminal function unit so that the desired transmission power is transmitted from the terminal function unit or the second receiver receives the desired reception power. The radio base station according to claim 1. A terminal function unit for testing a radio base station having a first transmitter and a first receiver of a communication terminal in a radio communication system, and for receiving an uplink signal transmitted from the terminal function unit and the communication terminal A second receiver configured by one or two systems, a second transmitter for transmitting a downlink signal transmitted to the terminal function unit and the communication terminal, and an input terminal of the second receiver connected to an antenna A path switching unit for switching between a signal transmission from the second transmitter and a signal route to the second receiver, and a base station control unit for controlling the base station A test method for a radio base station,
Receive test start instructions,
According to the test start instruction, the path switching unit terminates the input terminal of the second receiver, and according to the test start instruction, connects the desired second transmitter or second receiver and the terminal function unit,
(1) Receiving sensitivity measurement for adjusting the packet error rate to a predetermined range and obtaining receiving sensitivity based on the adjusted transmission power of the terminal function unit, and (2) Second transmitter and first transmitter of the terminal function unit And the second received power value of the terminal function unit when the second transmitter and the first receiver of the terminal function unit are connected to each other. Obtaining a difference between the first received power value and the predetermined first received power expected value, and a difference between the second received power value and the predetermined second received power expected value, A test method for a radio base station that controls measurement path diagnosis for diagnosing faults in the second receiver and the signal path depending on whether or not each is within a predetermined range.

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