KR100853496B1 - Apparatus and Method for Measuring the Power of Forwarding Signal In Base Transceiver Station - Google Patents

Abstract

The present invention can accurately measure the output power of the forward signal of the mobile communication base station that changes with time to enhance the system diagnostics and measure the power with a simple circuit without greatly modifying the existing power detector circuit. The present invention relates to an apparatus and a method for measuring a forward signal power of a mobile communication base station, and to an idle slot, an active slot, or a mixture of two slots of a forward signal of a mobile communication base station. Even when a signal is input, power measurement is possible, and the average output power of the base station can be measured more accurately by taking a method of calculating the average by converting the instantaneously measured power in watts (Watt), Ultimately, automatic base station output state on the base station manager And to obtain the effective performance of the effect.

Description

Apparatus and Method for Measuring the Power of Forwarding Signal In Base Transceiver Station}

1 is a view showing an output voltage of a general power detector.

2 is a view showing an output signal when measuring a CDMA2000 1xEV-DO signal with a general power detector.

3 illustrates a CDMA2000 1 × EV-DO forward link signal.

4 shows the characteristics of a log amp detector used for power detection.

5 is a diagram illustrating a result of measuring an idle slot of an EV-DO signal with an ADC.

6 is a diagram illustrating a procedure of a method for measuring output power of a base station according to the present invention.

7 is a block diagram illustrating an output power measuring apparatus of a base station according to the present invention.

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

31: MAC channel 32: Pilot channel                 

33: Data channel 50: Threshold

51: MAC / pilot channel section 52: noise section

71: power detector 72: ADC unit

73: average power calculation unit

The present invention relates to an apparatus and a method for measuring forward output power of a mobile communication base station, and more particularly, when a forward output signal such as a CDMA2000 1xEV-DO mobile communication base station processes an analog signal that is discontinuous or changes rapidly over time. The present invention relates to an apparatus and a method for measuring forward signal power of a mobile communication base station.

The 1xEV-DO (1x Evolution Data Only) system was later renamed Qualcomm's proposed High Data Rate (HDR), which was later renamed 1xEV-DO, to advance the standard to the 3GPP2 committee. The EV-DO system was drafted in December 2000, and its official name is High Rate Packet Data System, and the EV-DO system only serves data. This HDR uses a combination of time division multiplexing (TDM) and code division multiple access (CDMA) to share each channel with multiple users, but it does not have a fixed time band as in time division multiple access (TDMA). Take the format you use only when.

Unlike the previous protocol, the CDMA2000 1xEV-DO has a security layer separated from the air interface layer structure. This security layer provides authentication and encryption services for packet data services.

The CDMA2000 1xEV-DO radio interface has a layered structure, which includes an application layer, a stream layer, a session layer, a connection layer, a security layer, and a MAC. It consists of a layer (Medium Access Control Layer), physical layer (Physical Layer). Each layer consists of one or more protocols, each of which is negotiated individually.

The application layer may provide various programs, which provide a default signaling application for air interface protocol message transmission and a default packet application for user data transmission. The stream layer provides multiplexing of various application streams, with stream 0 limited to signaling and default to default signaling applications. Streams 1, 2, and 3 are not used by default. The session layer provides address management, protocol agreements, protocol configuration, and state maintenance services. The connection layer provides wireless link connection establishment and management services. The security layer provides authentication and encryption services, and the MAC layer defines the procedures used to receive and transmit to the physical layer. The physical layer provides a channel structure, frequency, power output, modulation, and encoding method for the forward link and the forward link.                         

Conventional CDMA signals, such as the IS-95A / B / C, are continuous signals that can be measured using common power detectors. The CDMA signal was received as the input of the power detector and the DC voltage from the log amp or the True Power Detector was read to measure the power. As a continuous signal, the power detector outputs a constant DC voltage. Therefore, there is no problem in reading the DC voltage in this case.

1 shows an output voltage of a general power detector.

That is, the operation of the general power detector is shown. When an analog signal having a certain frequency is input to the power signal, the power detector outputs a specific DC voltage according to the input power. The DC voltage has a specification for each power detector, and by measuring this value, the input power at that time can be known.

That is, the conventional CDMA signal was a signal with no change in power over time, and the power could be grasped with a detector output using a general power detector. However, in the case of CDMA2000 1xEV-DO, since power is turned on / off with time, power detection becomes difficult because power detection is performed in the same way as the existing CDMA signal, and thus the DC output is different depending on time.

2 illustrates an output signal when measuring an EV-DO signal with a general power detector.

As shown in FIG. 2, when the input signal changes rapidly with time, the output signal of the power detector also shows a different DC output with time, making power measurement difficult.

For the state management of the CDMA2000 1xEV-DO mobile communication base station, it is necessary to monitor whether the signal output of the base station is properly performed. For this reason, the need for measuring the forward signal power has emerged. However, due to the nature of the CDMA2000 1xEV-DO discontinuous signal, it was difficult to measure the output signal of the base station with conventional measurement equipment.

The present invention to solve the above problems, by securing the technology capable of measuring the forward signal power of the mobile communication base station to accurately measure the output power of the signal that changes over time to enhance the state diagnosis function of the system and An object of the present invention is to provide an apparatus and method for measuring a forward signal power of a mobile communication base station that can measure power with a simple circuit without greatly modifying the power detector circuit.

According to an aspect of the present invention, a method for measuring forward signal power of a mobile communication base station includes: determining a correlation between an input signal and an output signal of a power detector by measuring an output value for each section of a forward channel of the base station; Sampling with the ADC a predetermined number of times and using the correlation between the identified input signal and the output signal, calculating the average output power of the base station forward channel from the extracted data consisting only of the reference value or more of the sampled output value Steps.

The reference value is less than the minimum value of the measured values of the pilot channel and the MAC channel for a predetermined number of times, and exceeds the maximum value of the measured value of the output of the noise signal for a predetermined number of times.

In the step of calculating the average output power, if the average power of the signal including noise and garbage is to be measured, the output average of the base station is obtained using all the measured output values without selecting the output value using the reference value. The sampling stage ensures that the ADC's sampling rate is fast enough to extract the amount of data needed to derive the average over the pilot and MAC channel intervals.

In the method of calculating the average output power through the present invention, it is more preferable to use the power value in watts instead of averaging the power in dBm when calculating the average, instead of averaging the power value converted in watts. This is because the calculation is accurate.

According to another aspect of the present invention, an apparatus for measuring forward signal power of a mobile communication base station includes: a power detector configured to determine a correlation between an input signal and an output signal of a power detector by measuring an output value for each section of a forward channel of the base station; An analog-to-digital converter unit for sampling a predetermined number of times with an ADC, and an average of a base station forward channel from the extracted data consisting only of a value greater than or equal to a reference value among the sampled output values by using the correlation between the identified input signal and the output signal. It includes an average power calculator for calculating the output power.

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

Since the CDMA2000 1xEV-DO signal has more frequent irregularities over time than other standard signals, the present invention will mainly be described with reference to the case of 1xEV-DO.

The physical layer of 1xEV-DO is divided into a forwarding channel formed in the direction of the mobile station at the base station and a reverse channel formed in the direction of the base station at the mobile station, and in detail, several physical channels. Will exist. In the EV-DO forward signal, all physical channels are transmitted on one channel. Since time division multiplexing (TDM) is used, the multiple channels are logically time-divided, and the signals are physically spread ( Spread).

3 shows a CDMA2000 1 × EV-DO forward link signal.

As shown in FIG. 3, the slot structure of the forward channel includes 16 frames (16 slots = 26.67 ms) in one frame, and each slot is composed of two half slots (1/2 slot = 1024 chips). . Thus, one slot has 2048 chips, which is the smallest unit of time that contains practical information of 1.67ms in length.

The 1xEV-DO forward channel is divided into a pilot 32, a medium access control (MAC) 31, and a data (DATA) 33 channel. The slot structure of the forward channel is the data channel 33, the MAC channel 31, the pilot channel 32, the MAC channel 31, data in the unit of half slot when data is carried, that is, the active slot. The channel 33 is transmitted in order. In the case of an idle slot without data to be transmitted, the MAC channel 31, the pilot channel 32, and the MAC channel 31 are sequentially formed. Thus, the 1xEV-DO forward channel has a form in which the pilot channel 32, the MAC channel 31, and the data channel 33 are transmitted to the TDM in units of half slots.

Pilot channel 32 is used as a reference channel for coherent detection of an access terminal for the same purpose as used in IS-2000. The medium access control (MAC) channel 31 is mainly used for transmission rate control and transmits bit information, not message information, as a channel for transmitting information generated in a MAC layer. The MAC channel consists of a power control channel, a DRCLock channel, and an RA channel.

The power control channel is used to transmit a power control bit for the reverse traffic channel and the control channel. The power control channel is transmitted on the MAC channel by DRCLock channel and TDM method. The Date Rate Control Lock (DRCLock) channel is used to transmit information indicating whether the base station is normally receiving the reverse DRC channel to the terminal. The DRCLock channel is transmitted in a power control channel and TDM scheme. The Reverse Activity (RA) channel is used to transmit information indicating whether the base station is normally receiving the reverse traffic channel and information used by the terminal to determine the data rate of the reverse traffic channel to the terminal.

The pilot signal and the MAC signal are always present, and the DATA is a section in which a signal may or may not exist depending on the presence of a subscriber. In other words, in the case of 1xEV-DO, an overhead information channel, a pilot channel, a MAC channel, and the like occupy periodic time slots, and use the remaining time slots as a traffic slot of the user. Therefore, even in a traffic channel, a subscriber with a large amount of call occupies a large number of slots, and a subscriber with a small amount of call occupies a relatively small time slot, thereby occupying a time slot for a short time.

In the active slot of FIG. 3, all signals exist in the data 33 section, and in the idle slot, no signals exist in the data 33 section. In terms of power detection, the active slot detects a constant signal most of the time over time, whereas in the case of an idle slot, only the pilot channel 32 and the MAC channel 31 are used. Since the signal is not detected at all during the rest of the time, there is a problem in detecting the output of the base station using a general power detector. That is, in the case of an active slot, the power can be measured by a general power detector, but in the case of an idle slot, a measurement method different from the conventional method is required.

Then, the power measurement process of the EV-DO signal according to the present invention will be described with reference to FIGS. 4, 5, and 6.

6 is a flowchart illustrating a method of measuring output power of an EV-DO base station according to the present invention.

To measure the power of an EV-DO signal, first, it is important to accurately characterize the input and output signals of the power meter. The power meter has the characteristics of the input signal and the output signal in the parts specification for each part, but there are some deviations, so it is more accurate to measure the parts only by checking the parts.

4 shows the characteristics of a log amp detector used for power detection.

As shown in FIG. 4, the input signal of a typical log amp detector is expressed in dBm and the output signal is expressed in Voltage, indicating that the input and output signal units are expressed differently. In FIG. 4, it can be seen that the input signal and the output voltage expressed in dB scale of the log amp detector have a linear functional characteristic with a constant slope. That is, the following equation holds between the input signal and the output voltage.

V [Voltage] = a × P [dBm] + b

Where V is the output voltage, P is the input power, the coefficient a is the slope of the input signal and output signal characteristic graph, and b is the intercept of the Y-axis when the slope of the linear function is extended.

The above graph shows the characteristics of a typical log amp, where a and b are not absolute constants, but their values vary depending on the Peak to Average Power Ratio (PAPR), and may also vary by component.

When the average value is obtained with the output value shown in FIG. 4, since the output voltage of the input signal of the dB scale is averaged as it is, the difference by the dispersion term of the average voltage appears, resulting in an inaccurate average value. Will give birth.

Therefore, in the present invention, first, the output value is obtained by dividing each section according to the power level in order to increase the accuracy (S61), and connecting the respective sections to grasp the characteristics of the input / output signal of the power detector which is the actual measuring tool (S62). Should be. Since the characteristics of a typical log amp detector are represented by values close to the linear functions of the input and output, coefficients a and b of the linear function representing the characteristics of the log amplifier can be obtained on a graph representing the output according to the input (S63).

After determining the characteristics of the input signal and the output signal of the power detector, the output of the power detector is measured by an analog to digital converter (ADC) (S64).

The ADC itself converts an analog signal into a digital signal, but it should be considered that the present invention also functions as a kind of sampler. In order to obtain the average value, the analog value must be digitized. Sampling is required to collect basic data to obtain the average value.

In this process, the sampling rate of the ADC should be fast enough to make many measurements inside the pilot and MAC sections of the EV-DO signal.In order to obtain a reliable average value, the sampling rate is measured to have many data by measuring several slots. The number of times must also be adjusted. The sampling rate and the number of samplings are determined by the administrator based on the optimal value based on experience. You will need to provide a sampling rate and sampling frequency that will ensure average reliability, but economics will be one of the factors to consider. The actual measurement result will appear as shown in FIG.                     

5 illustrates a result of measuring an idle slot of an EV-DO signal with an ADC.

As shown in FIG. 5, the effective output value is shown in the pilot / MAC channel section 51, but only the output level of the noise level 52 is shown in the remaining part. To check whether the base station is generating a normal output, except for the noise signal, the output values of the pilot channel, the MAC channel, and the data channel output by the base station are only required. To this end, as shown in FIG. 5, a constant threshold value 50 is determined and the average is calculated using only the above value to obtain a reliable output value.

The reference value 50 is determined by referring to the value of the pilot / MAC channel section 51 and the value of the noise level 52. In the general case, the reference value 50 is less than the minimum value measured by the preset number of times the output value of the pilot channel and the MAC channel, and exceeds the maximum value measured by the preset number of times the output of the noise signal. It is a reasonable way to decide. Garbage data can be generated even when there is no signal in the DATA section according to the idle gain, so that the reference value can be positioned between the pilot, MAC signal and the garbage data signal.

When the reference value 50 is determined, only the effective values having a value exceeding the reference value 50 among the output values of the ADC are selected (S65), and the number N of effective values that is equal to or greater than the reference value 50 necessary for the average value calculation and the validity of the ADC are determined. Obtain instantaneous output values (S66).                     

In the next step, the average power is calculated by calculating only the effective value of the output value data of the power detector measured by the ADC.

If Equation 1 is modified, it can be expressed as Equation 2 below.

 P [dBm] = A × V + B

Here, P is instantaneous input power, and V is instantaneous output voltage.

Since a and b are measured in Equation 1, A and B can also be calculated. Here, the instantaneous input power P, [dBm] can be obtained from the instantaneous output value V and the variables A and B values extracted only with a value greater than or equal to the effective value (S67). Again, if P [dBm] is changed to P [Watt], the average power P _average [Watt] can be expressed as Equation 3 below.

In addition, an average value P _average [dBm] of actual measured power may be expressed as in Equation 4 below, where N is the number of valid data above the reference value.

Substituting Equation 3 into Equation 4 may be expressed as Equation 5 below.                     

Equation 5 represents a method of obtaining an average output of the base station from the measured instantaneous output voltage of the power detector, and the average output power P _average [dBm] of the base station can be obtained through the process of Equation 1 to Equation 5. (S68). Since the average power of Equation 5 is the average power in Watt unit and the result is expressed in dBm unit, it is different from the general method of measuring the power detector output and averaging the power in dBm as it is. The method according to the present invention will be referred to as a more accurate calculation method that can reduce the error that can come in the process of calculating the average from the values taken log.

In FIG. 5, the idle slot is assumed, but the active slot is not different from the idle slot, and can be measured through the same process. Only the pattern of the output signal is different, the method of determining the reference value 50 or the average calculation method will be the same.

If the average power including both the noise and garbage data is to be measured, the noise value and garbage data are included, not just the reference value 50 and only the data exceeding the reference value 50 are used. The total average power can be calculated by adding all the data to Equation [5].

Hereinafter, a method of obtaining the average value of the base station output according to the present invention will be described once again through FIG. 6.                     

First, in order to increase the accuracy, the output value of the power detector is obtained for each section according to the power level of the input signal (S61), and each section is connected to grasp the characteristics of the input / output signal of the power detector (S62). Since the characteristics of a typical log amp detector are approximated by a linear function of the input and output, coefficients a and b of Equation 1, which are linear functions representing the characteristics of the log amplifier, can be obtained on a graph representing an output according to the input ( S63).

After determining the characteristics of the input signal and the output signal of the power detector, the step of measuring the output of the power detector with an analog to digital converter (ADC) (S64). Only valid values having a value exceeding a threshold value 50 of the output values are selected (S65), and the number N of effective values or more effective instantaneous output values required for the average value calculation is calculated (S66).

The instantaneous input power P [dBm] can be obtained from the instantaneous output value V and the variables A and B values extracted using only the reference value 50 or more (S67). By obtaining instantaneous input power values in dBm, we can average the number of valid values. Log it again and multiply by 10 to get the average output power in dBm (S68). That is, the method for calculating the average according to the present invention can be summarized by converting the power measured in dB unit into watt units to obtain an average value of the power, and converting the power into dB units.

A method of directly calculating the output power of the base station from the output voltage, not the input voltage of the power detector, may be taken. The average output power of the base station P _average [ dBm] is how to get it.

7 shows a block diagram of a base station output power measurement apparatus according to the present invention.

As shown in FIG. 7, the base station output power measuring apparatus according to the present invention includes a power detector 71, an ADC unit 72, and an average power calculator 73.

The power detector 71 identifies the characteristics of the power detector by finding a correlation between the input signal and the output signal of the forward channel of the base station measured by the power detector.

The ADC unit (analog digital converter unit) 72 samples the output data of the forward channel detected by the power detector and converts it into digital data. In this case, the sampling rate is required to be fast enough to extract the amount of data necessary for deriving the average value even in the pilot channel and the MAC channel interval.

In the power calculation unit 73, the correlation between the input signal and the output signal of the power detector based on the results of the power detection unit 71 and the ADC unit 72 and the extracted data selected from the sampled output value Equation 5 is used to calculate the average output of the base station forward channel.

The present invention provides power measurement for idle slots, active slots of a CDMA20000 EV-DO forward signal, or when two slots are mixed, even when a signal having a rapidly changing value is generally changed over time. By taking the method of calculating the average by converting the instantaneously measured power in watts, it is possible to measure the average output power of the base station more accurately, and ultimately the base station output state on the base station manager. To achieve the effect of effective automatic diagnosis.

Claims (11)

In the base station output management method in the mobile communication base station manager, Determining the correlation between the input signal and the output signal of the power detector by measuring the output value for each section of the forward channel of the base station; Sampling the output signal of the forward channel a predetermined number of times; And Calculating an average output power of the base station forward channel from the extracted data consisting only of a value higher than or equal to a set reference value among the sampled output values by using the correlation between the identified input signal and the output signal. Method for measuring forward signal power. The method of claim 1, The reference value, A method of measuring forward signal power of a mobile communication base station, characterized in that the output value of the pilot channel and the MAC channel is less than the minimum value measured by the preset number of times, and exceeds the maximum value of the measured value of the noise signal output by the predetermined number of times. . The method of claim 1, In the sampling step, the sampling of the output signal of the forward channel is performed in the pilot channel and the MAC channel interval, characterized in that the forward signal power measurement method of the mobile communication base station. The method of claim 1, In the step of calculating the average output power, if you want to measure the average output power of the signal including noise and garbage (garbage), A method of measuring forward signal power of a mobile communication base station, wherein the average output power of the base station is obtained using all the output values measured without extracting data using the reference value. The method of claim 1, In the calculating of the average output power, the average output power is calculated by converting the power measured in units of dB to the unit of watts to obtain the average value of the power, and converting it into units of dB and displaying the calculated value. A method of measuring forward signal power of a mobile communication base station. The method of claim 5, The average output power (P _average ) is a method of measuring the forward signal power of the mobile communication base station calculated using the following equation.

Where V is the output voltage of the power detector, N is the number of valid data exceeding the reference value, and P is the instantaneous input voltage of the power detector. A base station output management apparatus in a mobile communication base station manager, A power detector to determine a correlation between an input signal and an output signal of the power detector by measuring an output value for each section of a forward channel of the base station; An analog-digital converter configured to sample the forward channel output value a predetermined number of times; And The mobile communication base station includes an average power calculation unit that calculates an average output power of the base station forward channel from the extracted data consisting only of a reference value or more among the sampled output values by using the correlation between the identified input signal and the output signal. Forward signal power measurement device. The method of claim 7, wherein The reference value, An apparatus for measuring forward signal power of a mobile communication base station, characterized in that the output value of the pilot channel and the MAC channel is less than the minimum value measured by the preset number of times, and exceeds the maximum value of the measured value of the noise signal output by the predetermined number of times. . The method of claim 7, wherein When the average power calculator is to measure the average output power of the signal including noise and garbage, the average output power of the base station is obtained using all the measured output values without extracting data using the reference value. An apparatus for measuring forward signal power of a mobile communication base station. The method of claim 7, wherein The average power calculator, The apparatus for measuring forward signal power of a mobile communication base station, wherein the average output power is calculated by converting the power measured in dB unit into watts unit, and calculating the average value of the power, and converting the power measured in dB unit. The method of claim 10, The apparatus for measuring forward signal power of a mobile communication base station, wherein the average output power P _average is calculated using the following equation.

Where V is the output voltage of the power detector, N is the number of valid data exceeding the reference value, and P is the instantaneous input voltage of the power detector.

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