KR20030034378A - Apparatus and method for fading test - Google Patents

Abstract

PURPOSE: A device of performing a fading test is provided to control an attenuating value by using a variable attenuator during a fading test of multipath, in order to enable a test of electric wave properties even when controlling power, thereby increasing test reliability. CONSTITUTION: A multipath fading unit(270) deteriorates electric waves transmitted from a mobile station(290). Attenuators(240,310) attenuate the deteriorated electric waves according to a substantial input level of a base station(210). Noise generators(350,360) apply noise set from outside to the deteriorated electric waves. A controller(370) sets the noise, measures an FER(Frame Error Rate), and monitors entire performance for an operator. The controller(370) controls measuring equipment, and receives power control information from the base station(210).

Description

Apparatus and method for fading test

The present invention relates to a fading test apparatus and a method thereof, and more particularly, a fading test for enabling a radio wave characteristic test even when power control is present in a multipath fading test according to a base station RF (Radio Frequency) characteristic test of a wireless communication network. An apparatus and a method thereof are provided.

In general, a wireless communication network such as a mobile communication network or a wireless local loop (WLL) operates a plurality of base stations located in place. The base station exchanges radio signals with a plurality of mobile stations (such as subscriber terminals for mobile communication) to mediate communication between the mobile station and the central switching station.

Fading phenomenon refers to the fluctuation of the received electric field strength at intervals of several seconds to several minutes when receiving radio waves from distant places. The fading phenomenon is classified into selective fading and synchronous fading according to frequency characteristics. Depending on the cause, there are fading such as coherence, polarization, and absorptivity. When radio waves are transmitted through different paths, the reflection in the ionospheric layer changes direction due to the influence of the supporter, or the amount of attenuation in the ionospheric layer changes. In particular, it greatly affects shortwave communication.

Multipath fading is a phenomenon in which radio waves pass through several different paths and arrive at an antenna with some delay, whereby the received electric field becomes strong or weakened by interference. This results in a strong or weakened combination of fast-arrived and low-waves. In short and microwave waves, multipath fading occurs by propagating through many passages because radio waves are reflected from the ground, buildings, and ionosphere. Accordingly, multipath fading at a base station of a wireless communication network using short waves is considered.

Therefore, the multipath fading test is included in the propagation characteristics of the base station in consideration of the propagation path when testing the RF reception characteristics.

1 is a block diagram of a base station reception test apparatus of a wireless communication network according to the prior art.

According to FIG. 1, the conventional reception test apparatus includes a noise generator 53 and 57 for applying additive white Gaussian noise to a signal transmitted from a mobile station 50, and a base station 10 to a signal transmitted from a mobile station 50. Variable attenuators 54 and 58 for attenuating the signal to match the input level of the fader, a fading emulator 52 for testing multipath fading, and signals from the transmit and receive ports of the base station 10 for simultaneous transmission and reception It includes a duplexer (51, 56) for the purpose of.

In addition, although the reception test apparatus of the base station is not shown in the accompanying drawings, the terminal management apparatus for managing the state of the mobile station 50, the base station management apparatus for managing the state of the base station and measuring the FER (Frame Error Rate) value, It further includes a power measurement device for monitoring the output on the transmission and reception path.

According to this configuration, the reception test apparatus performs a multipath fading test in an environment without power control. The signal transmitted from the mobile station 50 deteriorates via the multipath fading emulator 52 and then passes through different paths.

On each path through which the signal passing through the multipath fading emulator 52 is transmitted, the signal is applied with white Gaussian noise and attenuated according to the input level of the base station 10 via the attenuators 54 and 58, respectively.

Meanwhile, the noise generators 120 and 130 generate noise having a noise power density set from the outside.

Then, the signals attenuated by the attenuators 54 and 58, respectively, add noise generated from the noise generators 120 and 130 at the combiners 55 and 59 to form the received signals Rx_A and Rx_B on the respective paths. The received signal Rx_A is input to the receiving end of the base station through the duplexer 56, and Rx_B is directly input to the receiving end.

Here, the attenuation values of the attenuation units 54 and 58 are obtained using the path loss at the input of the base station receiving end and the measured power of the power meter. The FER is measured from the configured device and displayed on the monitor 140.

In this way, the multipath fading test is performed during the reception characteristic test using the reception test apparatus.

However, when the multipath fading test according to the prior art is performed in a code division multiple access (CDMA) environment, when the bandwidth is 1.23 MHz and the noise level is N, S = (Eb / No + N) using the set error rate Eb / No. The attenuation value of the attenuator is set so that the base station reception level is + 10 * log (data rate / 1.23M).

Therefore, when there is closed loop power control, since the base station reception level S is changed because Eb / No is changed, there is a problem that the fading characteristic test according to this method cannot be performed.

In addition, since multipath fading tests require testing for all conditions of various variables (speed, Eb / No, data rate), not only measurement time is required but also errors may be generated by the tester, which lowers the reliability of the test results. There is a disadvantage.

The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to control power by controlling attenuation using a variable attenuator during a multipath fading test according to a base station RF characteristic test of a wireless communication network. The present invention provides a fading test apparatus under power control in a wireless communication network capable of testing radio wave characteristics.

A fading test apparatus under power control in a wireless communication network of the present invention for achieving the above object comprises: a multipath fading unit for deteriorating radio waves transmitted from a mobile station of a wireless communication network; An attenuation unit for attenuating radio waves degraded by the multipath fading unit to match an actual input level of a base station; And a noise generator for generating a noise having a set noise power density and applying it to the radio waves through the attenuation unit.

Another object of the present invention is to control the attenuation value of the variable attenuator according to the power control information under the power control during the multipath fading test according to the base station RF characteristic test of the wireless communication network. It is to provide a fading test method.

In the wireless communication network of the present invention for achieving the above object, a fading test method under power control, comprising: performing a configuration and call setup for a multipath fading test between a base station and a mobile station; Setting a noise power density of a noise generator when the call setup is made; If the noise power density of the noise generator is set, controlling the attenuation value for the signal transmitted from the mobile station according to whether power control of the power of the transmission signal of the mobile station is being performed; And adding a noise generated by the noise generator to the attenuated signal and inputting the noise to the receiving end of the base station to perform a fading test by measuring the level of the received signal at the base station.

1 is a block diagram of a base station reception test apparatus of a wireless communication network according to the prior art.

Figure 2 is a block diagram of a fading test apparatus under power control of a wireless communication network according to an embodiment of the present invention.

3 is a flowchart of a fading test method under power control of a wireless communication network according to an exemplary embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

210: base station 220, 280: duplexer

230, 300: coupling portion 240, 310: attenuation portion

250, 320: voltage variable attenuator 260, 330: white Gaussian noise generator

270 multipath fading emulator

290: mobile station 350, 360: noise generator

370 control unit 380 monitor

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings.

2 is a block diagram of a fading test apparatus under power control according to an embodiment of the present invention, and FIG. 3 is a flowchart of a fading test method under power control according to an embodiment of the present invention.

According to FIG. 2, the present embodiment is applied to a reception test during a base station RF characteristic test under a CDMA environment, and includes a multipath fading unit 270 for deteriorating a radio wave transmitted from a mobile station 290, Attenuators 240 and 310 for attenuating to the actual input level of 210, noise generators 350 and 360 for applying externally set noise to the deteriorated radio wave, and set the noise and measure the FER And a control unit 370 for monitoring the performance of the operator, controlling the measurement equipment, and receiving power control information from the base station.

Radio waves transmitted from the mobile station 290 pass through the duplex 280 to distinguish between the signal transmitted from the mobile station 290 and the received signal in one antenna. The signal passing through the duplex 280 is degraded to fit the virtually set environment via the multipath fading emulator 270.

The degraded signal from fading emulator 270 goes through two paths. The white Gaussian noise is inserted through the white Gaussian noise generators 260 and 330 on each path, and attenuated to the input level of the base station 210 via the attenuators 240 and 310.

The noise generators 350 and 360 generate noise to be added to the corresponding signal on each path through which the degraded signal passes from the fading emulator 270. The noise generated by the noise generators 350 and 360 generates noise having a noise power density set from the outside.

Accordingly, the signal passing through the attenuators 240 and 310 is added with noise of the noise power density set in the combiner 230 and 300 from the noise generators 350 and 360 to form the received signals Rx_A and Rx_B. The Rx_A thus formed is input to the base station receiving end through the base station receiving end duplexer 220, and Rx_B is directly input to the base station receiving end.

In order to solve the problems caused by the multipath fading test under the conventional power control, voltage variable attenuation units 250 and 320 are further provided. The voltage variable attenuation units 250 and 320 may be implemented using a voltage controlled variable attenuator, and the attenuation values may be divided into and with and without power control.

First, when there is no power control, as described above, the radio wave is deteriorated according to the virtually set environment through the multipath fading emulator 270, and the white Gaussian noise generators 260 and 330 set Eb / No values. After each of the attenuators 240, 250, 310, and 320, the noise generated by the noise generators 350 and 360 is added by the combiners 230 and 300 and input to the receiver of the base station 210. As such, if there is no power control, there is no change in Eb / No, so the attenuation units 240 and 310 have a value corresponding to S = (Eb / No + N + 10 * log (data rate / 1.23M)). The attenuation units 240 and 310 should be set by subtracting by the center value of the variable attenuation ranges of the voltage variable attenuation units 250 and 320 from the calculated attenuation values.

In the case of power control, after the radio wave is deteriorated according to the virtually set environment through the multipath fading emulator 270, the white Gaussian noise generator 260 and 330 sets the Eb / No value, and the attenuation unit 240, 250. Noise generated by the noise generators 350 and 360 via 310 and 320 is added to the combiner 230 and 300. The signal passing through the combiner 230, 300 is input to the receiver of the base station 210. If there is closed loop power control, the value of Eb / No changes, so the value of the base station reception level is S = (Eb / No + N + 10 * log (data rate / 1.23M)).

Therefore, the attenuation values of the attenuation units 240 and 310 that attenuate the radio wave so that a constant reception level is input to the base station should be compensable according to the change of Eb / No. That is, the base station 210 informs the mobile station at a predetermined time period (1.25 msec, etc.) whether the strength of the received signal is high or too low. Control.

In the process of constantly adjusting the strength of the signal reaching the base station from the mobile station, the base station receiving demodulator increases power by comparing the measured Eb / No reference value with the received measured Eb / No value at a predetermined time period (1.25 msec, etc.). A command for instructing whether or not to lower the speed is put on the power control subchannel to control the mobile station. At this time, the Eb / No reference value is determined by the outer loop power control according to the target value of the reverse call channel designated by the operator.

Since the mobile station increases or decreases the output according to the indication value of the base station transmitted through the power control channel, the controller 370 receives this information and increases or decreases the attenuation values of the voltage variable attenuation units 250 and 320 according to the increase and decrease of the base station output. Then, a signal of the same size enters the receiving end of the base station, so that a multipath fading test can be performed even in an environment with power control.

In addition, since the multipath fading test needs to be measured for all conditions in consideration of a change in speed, a data rate, and a change in Eb / No, the controller 370 manipulates the series of conditions. The controller 370 controls the measurement to a multipath paging emulator, a power meter for measuring power on a path, a noise generator for applying a desired Eb / No, and a noise generator for generating noise of noise power density required for a base station test. . Therefore, the control unit 370 automatically sets the meter for all conditions required for the multipath fading test, measures the value, and measures the FER value from the base station 210 and displays it on the monitor 380.

Next, a fading test method under power control in a wireless communication network applied to a fading test apparatus under power control in a wireless communication network as described above will be described.

Referring to FIG. 3, when a multipath fading test of a base station is to be performed, the controller 370 sets an initial environment for each variable. Since an item for setting the initial environment by the controller 370 may be different for each test item, an appropriate variable is initialized (S310).

When the initial configuration is made, a call setup is performed for the multipath fading test between the base station 210 and the mobile station 290 (S320).

Then, the noise power density of the noise generators 350 and 360 is set (S330).

When the noise generators 350 and 360 are set, the fading emulator 270 is operated to deteriorate the signal transmitted from the mobile station 290 (S340).

In the case of performing attenuation on the signal degraded by the fading emulator 270, the attenuation value is changed depending on whether or not power control is performed. Therefore, it is first determined whether power control is performed (S350).

If the power control is being performed, the controller 370 varies the attenuation value by using the power control information for the mobile station 290. This is achieved by receiving the output variable information of the mobile station 290 generated by the power control and varying the attenuation values of the voltage variable attenuation units 250 and 320 (S360).

When the attenuation values of the voltage variable attenuators 250 and 320 are varied in step S360 or when it is determined in step 350 that power control is not performed, the noise generators 350 and 360 generate the attenuated signals. After adding the noise to the base station receiving stage to measure the base station reception level (S370).

After the base station reception level is measured, the necessary test for each item is performed (S370).

As such, the present embodiment can maintain the reception level of the base station receiving end even under power control by using the voltage variable attenuator, thereby enabling multipath fading test.

The embodiments described above are within the scope of various changes, modifications, and equivalents of the present invention. Therefore, the present invention is not limited to the description of the examples.

According to the fading test apparatus and the method of the present invention has the following effects.

First, it is possible to increase the reliability of the test results by minimizing the errors that can be generated by the tester due to the automation of the test environment.

And by automating repetitive tasks for manipulating various variables (speed, Eb / No, data rate), the time required for multipath fading test can be shortened.

In addition, even in a multipath fading environment with closed loop power control, it is possible to test whether the propagation characteristic of the base station satisfies the characteristic specification.

Claims (4)

A multipath fading unit for degrading radio waves transmitted from a mobile station of a wireless communication network; An attenuation unit for attenuating radio waves degraded by the multipath fading unit to match an actual input level of a base station; And a noise generator for generating a noise having a set noise power density and applying it to the radio wave through the attenuation unit. The method of claim 1, And a control unit for setting the noise power density of the noise to be generated by the noise generating unit, measuring the FER to monitor the overall performance to the operator, controlling the measurement equipment, and receiving power control information from the base station. Fading test apparatus under power control in a communication network. Performing configuration and call setup for multipath fading testing between the base station and the mobile station; Setting a noise power density of a noise generator when the call setup is made; If the noise power density of the noise generator is set, controlling the attenuation value for the signal transmitted from the mobile station according to whether power control of the power of the transmission signal of the mobile station is being performed; And adding a noise generated by the noise generator to the attenuated signal and inputting it to a receiving end of a base station to perform a fading test by measuring a level of a received signal at a base station. Fading test method. The method of claim 3, wherein when power control is performed on a transmission signal of the mobile station, Fading test under power control in a wireless communication network, characterized by receiving the output variable information of the mobile station generated by the power control and controlling the voltage variable attenuation unit to vary the attenuation value of the voltage variable attenuation unit so that the base station reception level is constant. Way.