KR100438543B1 - Apparatus for measuring transmission power in code division multiple access communication - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission power measuring apparatus of a mobile communication base station, and in particular, PLL tuning time in pure multi FA power detection time by sequentially PLL tuning the FA to detect a channel for each FA when outputting the multi FA to a transmitting antenna. In addition, there were many problems in real-time power detection. In addition, undesired power is added to pure power during A / D conversion, resulting in poor power monitoring accuracy, and the use of numerically controlled oscillators to downconvert A / D converted signals to baseband, resulting in overall noise and unwanted wave generation. There is a problem that the accuracy is reduced during power monitoring. Accordingly, the present invention can measure the channel power simultaneously for each FA by connecting a plurality of digital FIR filters in parallel to the output terminal of the A / D converter, and obtain the total power for each transmission antenna sector by adding the channel power for each FA. There is an advantage that it can.

Description

Transmission power measuring apparatus of mobile communication base station {APPARATUS FOR MEASURING TRANSMISSION POWER IN CODE DIVISION MULTIPLE ACCESS COMMUNICATION}

The present invention relates to an apparatus for measuring transmission power of a mobile communication base station. In particular, by connecting a plurality of digital filters to a digital output terminal in parallel, the total power for each transmission antenna sector can be measured by adding channel power for each FA or channel power for each FA. It relates to a transmission power measuring apparatus that can be.

1 is a system block diagram including a transmission power measuring apparatus of a mobile communication base station according to the prior art.

Referring to FIG. 1, in general, a base station transmission power control apparatus converts a transmission output coupled through a directional coupler 20 into a digital signal at a base station final output stage, and then estimates / detects transmission power. 100); The transmission power control unit 30 receives the measured transmission power and controls the base station transmission power, and is used to compensate for distortion and loss of the transmission signal.

The apparatus 100 for measuring transmission power includes an analog signal processor 10 for coupling a base station final transmission output, canceling and amplifying noise in the signal, and outputting the signal as a digitally convertible signal; An A / D converter 6 for sampling the analog signal output from the analog signal processor 10 and outputting sample data; A digital signal processor (7) for receiving the sample data and converting the sample data into data having a frequency spectrum symmetrical on the frequency axis and then squared to remove the DC component to output measured data; A storage unit 8 for outputting the measurement data according to a control signal; And a CPU 9 for outputting a control signal to each of the components and outputting the measurement data to the transmission power control section 30.

The operation description in the state configured as above is as follows.

First, the final output signal of the antenna is measured by the transmission power measuring apparatus 100 in order to control the power of the signal transmitted through the antenna.

For this purpose, the final output signal is coupled by the directional coupler 20 and input to the transmission power measuring apparatus 100.

The input signal coupled at the final output stage is as follows.

......... (Eq. 1)

(Frf is the frequency band you want to measure)

The input final output signal is band limited by the band pass filter 1, where signal components of the required frequency band are present and other components are removed.

The band limited signal is input to the mixer 2A, so that an intermediate frequency signal mixed with the local frequency output from the PEL unit 2B is generated. The intermediate frequency signal is as follows.

....... (Equation 2)

(delF is the frequency band you want to measure)

The intermediate frequency signal is filtered back to the specific channel frequency signal by the surface acoustic wave band pass filter 3 having good band limitation characteristics in order to measure the power of the specific channel.

The signal band-limited by the surface acoustic wave band pass filter 3 is maintained at a constant level by the attenuator 4 and the amplifier 5 and input to the A / D converter 6.

The A / D converter 6 samples and outputs a specific channel signal of a transmission output of an intermediate frequency band according to a sampling clock, and the output signal is as shown in Equation 3 below, and the frequency of the sampled signal is Equation 4 approaches the baseband.

{V} _ {a} (t) = {V} _ {if} (t) * sample (t) .......... (Equation 3)

(t = n / {F} _ {s} n is an integer of 1 or more.

{F} _ {s} is the A / D converter clock frequency (or sampling frequency)

Here, the {F} _ {s} selection condition is set to a value of twice the bandwidth of the intermediate frequency signal so that no unwanted wave is generated at the output of the A / D converter after the intermediate frequency signal is sampled by the A / D converter. )

{f} _ {d} = m * {f} _ {s}-{f} _ {if} or {f} _ {d} = m * {f} _ {s}-{f} _ {if } (Equation 4)

({f} _ {d} is the output sampling signal frequency of the A / D converter close to the baseband,

{f} _ {s} is the frequency of the sampling clock,

{f} _ {if} is the frequency of a specific channel signal of the transmit output input to the A / D converter)

A sampling signal having a frequency component of {f} _ {d} output from the A / D converter 6 is input to the digital signal processor 7, and the structure of the digital signal processor 7 is illustrated in FIG. 2. As shown, it works as follows.

The digital mixer 7A mixes the frequency component of {f} _ {d} generated by a numerically controlled oscillator (7B) with the input sampling signal to down-convert to baseband.

A squarer 7C squares the digital baseband signal to convert a digital voltage signal in volts into a digital power signal in watts.

The digital power signal is transmitted to the first moving average filter MA1 (7D) so that the baseband power components are filtered in the frequency domain, and the signal components are converted into average values in the time domain. The first moving average filter 7D is designed as a digital filter in the form of an FIR filter, and the frequency response of the moving average filter 7D is expressed by Equation 5 below.

......... (Equation 5)

The WCDMA power signal from which high frequency components are removed and only pure power spectral components close to the base band are extracted is stored in the storage unit 8, and is stored in the storage unit 8 when the central computing unit (CPU) 9 requests it. The power signal is transmitted to the computing device 9.

The central processing unit 9 transmits the digital value of the WCDMA final output coupling signal of the specific channel stored in the storage unit 8, that is, the power signal of the final output coupling signal to the transmission power control unit 30.

The central computing unit (CPU) 9 receives the digital power signal stored in the storage unit 8 and the compensation data according to the current temperature measured by the temperature sensor, and transmits the measured power value corresponding thereto. Output to

The transmission power control unit 30 controls the WCDMA final transmission output power using the strength of the WCDMA final output coupling signal transmitted from the central computing unit 9.

However, the above prior art has the following problems.

First, when the multi-FA is to be output to the transmitting antenna, in order to detect the channel power for each FA in the transmission power measuring apparatus, by sequentially PLL tuning for each FA, the PLL tuning time is added to the pure multi-FA power detection time, thereby real-time power detection. There is a problem that the time required to increase.

Second, when data is converted from analog to digital signals, when an unwanted signal is generated in the out band, unwanted power is added to pure power, which causes a problem in that precision is reduced during power monitoring.

Third, since a numerically controlled oscillator is used to down-convert the signal output from the A / D converter to the baseband, there is a problem in that accuracy is reduced during power monitoring due to generation of total noise and unwanted waves.

Accordingly, the present invention has been made to solve the above-mentioned conventional problems, by connecting a plurality of digital filters in parallel to the digital output stage, and adding the channel power for each FA or the channel power for each FA, and total power for each transmission antenna sector. It is an object of the present invention to provide a mobile communication base station transmission power measuring apparatus capable of measuring.

One embodiment of the present invention for achieving the above object is an analog signal processing unit for coupling the base station final transmission output to cancel and amplify the noise in the signal to output a digitally convertible signal; An A / D converter for sampling the analog signal output from the analog signal processor and outputting sample data; A digital signal processor for filtering and storing a plurality of FAs output from the A / D converter, converting a signal of a specific channel output according to a control signal from a controller into an absolute value and averaging the sum of the sampling voltages. Wow; And a controller configured to convert the average voltage output from the digital signal processor into a power value and output the converted power value.

1 is a system block diagram including a mobile communication base station transmit power measuring apparatus according to the prior art.

2 is an internal block diagram of a digital signal processing unit according to the prior art.

3 is a system block diagram including a mobile communication base station transmit power measurement apparatus according to the present invention.

4 is an internal block diagram of a digital signal processing unit according to the present invention;

** Description of symbols for the main parts of the drawing **

1: Band Pass Filter 2A: Mixer

2B: PLL 3: Surface acoustic wave filter

4 attenuator 5 amplifier

6: A / D converter 7 ': Digital signal processor

9: CPU 10: analog signal processing unit

20: directional coupler 30: transmit power control unit

200: transmission power measuring device

Hereinafter, an embodiment according to the present invention will be described in detail with reference to the accompanying drawings.

3 is a block diagram illustrating a system including a mobile communication base station transmit power measurement apparatus according to the present invention.

Referring to FIG. 3, an apparatus for measuring transmission power of a mobile communication base station includes an analog signal processor 10 for coupling a base station final transmission output, noise canceling and amplifying the signal, and outputting the signal as a digitally convertible signal; An A / D converter 6 for converting an analog signal output from the analog signal processor 10 into digital and outputting the digital signal; Filters and stores a plurality of FAs output from the A / D converter 6, converts a signal of a specific channel output according to a control signal from the CPU 9 to an absolute value, and averages the sum of the sampling voltages. A digital signal processor 7 'for outputting; And a CPU 9 for converting the average voltage output from the digital signal processor 7 'into a power value and outputting the converted power value.

Since the analog signal processor 10 is the same as described above in the related art, a detailed description thereof will be omitted.

4 is an internal block diagram of a digital signal processor according to the present invention.

Referring to FIG. 4, the digital signal processing unit 7 ′ is a finite impulse response filter unit in which a plurality of finite impulse response filters (referred to as FIR filters in the drawing; hereinafter described as FIR filters) for removing high frequency signals are connected in parallel. (7'A; denoted by the FIR filter portion in the drawing; hereafter described as the FIR filter portion); A plurality of registers respectively storing the signals output from the respective FIR filters are connected in parallel, and the storage unit 7'B receives a register selection signal from the CPU 9 and outputs a signal stored in a corresponding register. )Wow; An absoluteizer 7'C (shown as ABS in the figure, hereinafter referred to as ABS) for converting a signal output from the storage portion 7'B to an unsigned signal value and generating an absolute value thereof; A moving average filter 7'D (shown as MA in the drawing, hereinafter referred to as MA) for outputting the sum of the sampling voltages divided by the sampling number.

The description of the operation in the state configured as described above is as follows.

In FIG. 3, the process until the {V} _ {a} (t) is output from the A / D converter 6 is the same as the above-described conventional technique, and thus, the description of {V} _ {a} (t) is omitted. The operation description of the input digital signal processor 7 'is as follows.

The output signal from the A / D converter 6 is a sum of a desired signal and an undesired signal, and when inputted to the FIR filter unit 7'A, passes through four FIR filters. The magnitude Vf (t) is output, which is input to and stored in four registers connected in parallel with the respective FIR filters to the storage 7'B.

The storage unit 7'B outputs the FA signal stored in the register corresponding to the register selection signal from the CPU 9 to the ABS 7'C.

The ABS 7'C converts the output from the storage 7'B into an unsigned signal and inputs it to the MA 7'D.

The MA 7'D outputs a value obtained by dividing the sum of the sampling voltages by the number of samplings. The output value is expressed by Equation 6 below.

1 / n SUM from n = 1 to n = Vf (t) ....... (Equation 6)

t = n / F _s n = 1, 2, 3, ...

The CPU 9 converts the average voltage into a power value in units of dBm according to Equation 7 below, and outputs it.

10 Log [1 / n SUM from n = 1 to n = Vf (t)] ² ....... (Equation 7)

The value output from the CPU 9 is output to the transmission power control unit 30 so that the final transmission power is adjusted by the transmission power control unit 30.

The present invention is not limited to the embodiments described above, and various modifications and changes can be made by those skilled in the art, which are included in the spirit and scope of the present invention as defined in the appended claims.

Effects of the present invention discussed above are as follows.

First, when the multi-FA is output to the transmitting antenna, the transmission power measuring device does not need to sequentially tune the RF PLL for each FA in order to detect the multi-FA channel power, so that real-time power can be detected by reducing the time required for power detection. Do.

Second, when converting data from analog to digital, unwanted signals in the outband are removed by the digital FIR filter, thereby improving accuracy in detecting channel-by-channel or total power power.

Third, the antenna transmit power measurement effect for each channel.

Fourth, there is a total power measurement effect for each transmit antenna sector.

Claims (3)

An analog signal processing unit coupling the base station final transmission output to cancel and amplify noise in the signal and output the digital conversion signal; An A / D converter for sampling the analog signal output from the analog signal processor and outputting sample data; A digital signal for digitally filtering and storing a plurality of FAs output from the A / D converter, and converting a signal of a specific channel output according to a control signal from a controller into an absolute value and averaging the sum of the sampling voltages. A processing unit; And a control unit for converting the average voltage output from the digital signal processing unit into a power value and outputting the converted power value. The method of claim 1, wherein the digital signal processing unit A finite impulse response filter connected in parallel with a plurality of digital filters for removing high frequency signals; A plurality of storage units for storing signals output from the respective digital filters are connected in parallel, and a storage unit for outputting a signal according to a storage unit selection signal from the controller; An absoluteizer for converting a signal output from the storage unit into an unsigned signal value and generating an absolute value thereof; And a moving average filter for dividing and outputting the sum of the sampling voltages by a sampling number. An A / D converter for converting an output signal of a transmitting end into a digital signal; A finite pulse response filter comprising a plurality of digital filters configured to remove high frequency signals of a plurality of FA signals output from the A / D converter; A digital signal processing unit configured to store a signal output from each of the digital filters, and to store a plurality of registers for outputting according to a selection signal, and means for obtaining an average value of an absolute value of time of an output signal of the storage unit. Transmission output measuring apparatus of a mobile communication system comprising a.