JP2006003228A - Propagation loss measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a propagation loss measuring device capable of mechanically and effectively checking as to whether or not all measured data are measured correctly in a propagation loss measurement. <P>SOLUTION: The propagation loss measuring device is equipped with a reception means which receives an electric wave having a reference frequency different from a frequency to be measured; a propagation loss calculation means which calculates a propagation loss of the electric wave having the reference frequency: and a detection means which detects a measurement error, based on propagation losses of electric waves having the frequency to be measured and the reference frequency. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a propagation loss measuring apparatus that performs radio wave measurement in mobile radio communication.

  The difference between the power of the radio wave radiated from the transmitting antenna and the power of the radio wave received by the receiving antenna is called propagation loss. When the transmitting and receiving antennas have directivity, the value excluding this directivity gain is used as the propagation loss. In mobile communication, it is possible to estimate the size of an area covered by one base station by grasping this propagation loss with respect to the distance between transmission and reception. This propagation loss is obtained by measuring the received power in a radio wave of known power transmitted from the transmitter.

  Also, the propagation loss between the base station and the mobile station in mobile communication varies depending on the position of the mobile station. Even if the distance to the base station is the same, the propagation loss changes if the environment around the mobile station is different. For this reason, the value of the propagation loss also changes as the mobile station moves.

  Propagation loss is measured outdoors, but measurement errors are likely to occur in outdoor measurements.

  The cause of this measurement error is a failure of the measuring instrument. The failure of the measuring instrument means that the transmission power of the specified value is not output halfway or the output from the receiver is not a correct value. In the outdoor measurement, the probability of failure of the measuring device increases due to vibrations caused by moving in a car, weather conditions such as temperature and humidity, noise typified by urban noise, and the like, as compared to measurement in a laboratory. A completely broken measuring instrument can find its faults with prior confirmation, but faults that sometimes occur during measurement are less likely to be found.

  In addition, errors due to human carelessness can be cited as causes of measurement errors. An error due to human carelessness is an error in setting the measuring instrument or an error in recording the measurement status.

  Moreover, the presence of interference waves can be cited as a cause of measurement errors. The interference wave is a radio wave of the same frequency radiated from another interference source in addition to the desired wave when the radio wave transmitted from a predetermined transmitter is a desired wave. Since this interference wave cannot be distinguished from the desired wave, the reception level of the desired wave cannot be measured correctly at a place where the interference wave exists. In addition, since interference sources exist randomly in the city, interference waves cannot generally be avoided.

  As described above, in the measurement of propagation loss, if a human error occurs in the middle of the measurement, if the measuring instrument temporarily malfunctions and then returns to normal, interference occurs in addition to the desired wave from the location being measured. You may be measuring a wave. In such a case, it is not known whether the propagation loss values obtained by measurement are all correct values.

  One way to prevent measurement errors is to find a malfunction of the measuring device before the measurement. A method for confirming the malfunction of the measuring device will be described with reference to FIG.

  FIG. 1A shows a method of confirming whether a correct value is obtained by connecting a transmitter and a receiver with a wire, for example, a high-frequency cable, before measurement. In FIG. 1A, 1 is a transmitter, 2 is a receiver, 3 is a data recording device, 4 is an attenuator, and 5 is a high-frequency cable. The receiver 2 is connected to the attenuator 4 and the data recording device 3. The transmitter 1 and the attenuator 4 are connected by a high frequency cable 5.

  In this method, the attenuator 4 corresponds to the propagation loss between the transmitter 1 and the receiver 2. That is, the amount of attenuation by the attenuator 4 corresponds to the propagation loss. In this method, the attenuation amount is changed by the attenuator 4, the reception level of the radio wave transmitted from the transmitter 1 is measured by the receiver 2, and the correct propagation loss is obtained from the measurement data recorded in the data recording device 3. To check.

  In addition, a method for confirming the malfunction of another measuring device will be described with reference to FIG. In this method, measurement is interrupted in the middle of measurement, and the output of the transmitter and the reception characteristics of the receiver are individually confirmed.

  An example will be described in which the transmitter 1 is on a steel tower 10 and the receiver 2 is on a distant road 20, for example.

  A transmitter 1 and a wattmeter 6 connected to the transmitter 1 via a wire, for example, a high-frequency cable 5 are installed on the steel tower 10. A receiver 2, a data recording device 3 connected to the receiver 2, and a standard signal generator 7 connected to the receiver 2 via a wire, for example, a high-frequency cable 5 are installed on the road 20. Has been.

  On the transmitter 1 side, the value of the transmission output is confirmed by the wattmeter 6. On the receiver 2 side, the standard signal generator 7 is used to confirm the reception characteristics of the receiver.

These confirmations can detect some malfunctions of the measuring instrument. However, in any of the methods, since the confirmation work is performed separately from the measurement act, it is not possible to find a problem that occurs during actual measurement. In addition, countermeasures against artificial measurement errors and interference waves must be taken separately. There is a way to search for measurement errors due to the unnaturalness of the measured data after measurement, but unnaturalness can only be relied on experience and intuition.
"Radio Wave Propagation Handbook", Yoshio Hosoya Planning and Supervision, Realize, pp.204-205, January 28, 1999 M.Hata, “Empirical formula for propagation loss in land mobile radio service”, IEEE Trans. Veh. Technol. VT-29 [3] pp.317-325, 1980 Mitsuro Kitao, Shinichi Ichitsubo, "Microcell Propagation Loss Estimation Formula for 400MHz to 8GHz", 477th Radio Research Laboratory F Subcommittee (URSI-F Subcommittee), September 23, 2003

  However, the background art described above has the following problems.

  The above-described method has a problem that it is difficult to find a measurement error that temporarily occurs during measurement.

  Also, searching for measurement mistakes from measurement data requires experience and intuition, and there is a problem that it cannot be performed mechanically efficiently.

  There is a demand for a method of confirming that all measured data are correct values, not measurement errors. In addition, it is desired that this confirmation can be performed mechanically and efficiently with a computer or the like without depending on experience and intuition.

  Therefore, an object of the present invention is to provide a propagation loss measuring apparatus that can mechanically and efficiently confirm whether or not all measurement data are correctly measured in propagation loss measurement.

  In order to solve the above problems, a propagation loss measuring apparatus of the present invention includes a receiving unit that receives a radio wave having a reference frequency different from a frequency to be measured, a propagation loss calculating unit that calculates a propagation loss of a radio wave having a reference frequency, Detecting means for detecting a measurement error based on propagation loss of radio waves of the measurement frequency and the reference frequency. With such a configuration, a measurement error can be mechanically detected.

  According to the embodiment of the present invention, it is possible to realize a propagation loss measuring apparatus capable of mechanically and efficiently confirming whether or not all measurement data are correctly measured in propagation loss measurement.

Next, embodiments of the present invention will be described with reference to the drawings.
In all the drawings for explaining the embodiments, the same reference numerals are used for those having the same function, and repeated explanation is omitted.

  As an estimation formula created for estimating the propagation loss characteristic in mobile communications, there is an “Okumura-Kashiwa formula” (see, for example, Non-Patent Documents 1 and 2). The basic part of Okumura-Kashiwa type is as follows.

Loss = 69.55 + 26.16 log (f) −13.82 log (Hb) + [44.9−6.55 log (Hb)] log (d) + a (Hm) [dB] (1)
Here, Loss is a propagation loss [dB], f is a frequency [MHz], Hb is a base station antenna height [m], d is a transmission / reception distance [km], and Hm is a mobile station antenna height [m], a (Hm) is a mobile station antenna high characteristic.

  From the equation (1), it can be seen that the propagation loss changes depending on the frequency f of the radio wave. For example, it can be seen that the frequency difference between 800 MHz and 2000 MHz is a propagation loss difference of 10.4 dB (= 26.16 log [800/2000]). It should be noted that this difference in propagation loss does not depend on the measurement environment such as the base station antenna height and the distance between transmission and reception. This is clear from the expression (1) because the term of the frequency f is independent of other parameters.

  FIG. 2 shows the correlation characteristics of propagation loss when the frequencies are different (see, for example, Non-Patent Document 3). This correlation characteristic is a propagation loss characteristic obtained by installing two transmitters with frequencies of 812 MHz and 3350 MHz on the roof of a building and simultaneously measuring the reception levels of the two frequencies with a measurement vehicle. The measuring vehicle traveled randomly within a range of 1 km from the transmission point. One point of data is an average value of a 50 m travel section, and FIG. 2 is a result of traveling 25 km.

  As can be seen from FIG. 2, the difference between the two propagation losses is constant everywhere. The average of the two-wave propagation loss difference is 13.8 dB, and the variation of the propagation loss difference is 3.0 dB in standard deviation. In this measurement, 2200 MHz, 5200 MHz, and 8450 MHz were simultaneously measured in addition to the two frequencies. As a result, the standard deviation of the propagation loss difference at each frequency was 2 to 3 dB.

  From these facts, two or more frequencies are measured at the same time, and the difference in propagation loss is compared. If a difference greater than a certain value occurs, it can be determined that a measurement error has occurred. In this case, if transmission / reception devices are prepared independently for each frequency, the measurement systems become independent from each other. Therefore, the probability that measurement mistakes occur at the same value at the same time decreases, and the reliability of detection of measurement mistakes increases. In addition, the transmission antennas for each frequency are installed at the same height, such as the same building rooftop or steel tower platform, and the reception antennas are installed at the same height, such as the roof of the same measurement car. Propagation loss independent of point location is obtained.

  In addition, the difference in propagation loss obtained by the measurement is obtained by a computer, and the uncertain data can be easily removed by labeling the measurement data whose difference is a certain value or more.

  Next, a propagation loss measuring apparatus according to the first embodiment of the present invention will be described with reference to FIG. The propagation loss measuring apparatus according to the present embodiment measures a propagation loss between a base station and a mobile station in a mobile communication system in which the base station communicates with a mobile station located within the service area.

  As shown in FIG. 3A, the propagation loss measuring apparatus 200 includes a receiving unit 201, an antenna 202 connected to the receiving unit 201, a receiving unit 203, an antenna 204 connected to the receiving unit 203, and a reception. A data recording unit 205 connected to the unit 201 and the receiving unit 203, and an arithmetic unit 206 connected to the data recording unit 205.

  The base station 100 includes a transmission unit 101, an antenna 102 connected to the transmission unit 101, a transmission unit 103, and an antenna 104 connected to the transmission unit 103.

  The transmission unit 101 transmits a radio wave having a frequency to be measured, that is, a frequency to be measured, via the antenna 102. The receiving unit 201 receives the radio wave transmitted from the antenna 102 via the antenna 202. The transmitting unit 103 transmits a radio wave having a reference frequency different from the frequency to be measured via the antenna 104. The receiving unit 203 receives the radio wave transmitted from the antenna 104 via the antenna 204. The received radio wave reception level data is recorded in the data recording unit 205. The calculation unit 206 obtains a propagation loss from the reception level data received by the receiving units 201 and 203 and recorded in the data recording unit 205, and obtains a difference in propagation loss. In addition, it is determined whether or not the obtained difference in propagation loss satisfies a preset setting value. If it is satisfied, recording is performed, and if not, an error flag is attached.

  Further, the average value of the reception levels is obtained, the difference between the average values of the two reception levels is obtained, it is determined whether or not the difference between the average values satisfies a preset setting value, and if it is satisfied, the record is made. If not, an error flag may be added.

  Next, the calculation unit 206 will be described in detail with reference to FIG.

  The calculation unit 206 includes a propagation loss calculation unit 207 and 208 connected to the data recording unit 205, a propagation loss determination unit 209 connected to the propagation loss calculation unit 207 and 208, and a defect connected to the propagation loss determination unit 209. A data detection unit 210. A propagation loss determination value is input to the propagation loss determination unit 209.

  The propagation loss calculation unit 207 calculates the propagation loss of the radio wave received by the reception unit 201 and inputs the calculated propagation loss to the propagation loss determination unit 209. Also, the propagation loss calculation unit 208 calculates the propagation loss of the radio wave received by the reception unit 203 and inputs the calculated propagation loss to the propagation loss determination unit 209. The propagation loss determination unit 209 determines the difference between the input propagation losses, determines whether the calculated propagation loss difference satisfies a predetermined determination value, and inputs the result to the defect data detection unit 210. For example, when the allowable value of the propagation loss difference is set as the determination value, the propagation loss determination unit 209 determines whether or not the obtained difference in propagation loss is within the determination value.

  When the result indicating that the propagation loss difference is within the determination value is input, the defect data detection unit 210 records the measured value as correct. In addition, when a result indicating that the propagation loss difference is not within the determination value is input, the defect data detection unit 210 adds an error flag to the measurement value.

  Next, the operation of the propagation loss measuring apparatus according to the present invention will be described with reference to FIG.

  First, the reception levels of radio waves at the frequency to be measured and the reference frequency are measured (step S402). Next, the propagation loss of the radio waves of the received measured frequency and reference frequency is calculated (step S404), and the propagation loss difference is calculated using these results (step S406).

  Next, it is determined whether or not the calculated difference in propagation loss is within a preset setting value (determination value) (step S408). If the result of determination in step S408 is that the propagation loss difference is within the set value (step S408: YES), the measured value is recorded as a correct value (step S410). On the other hand, if the result of determination in step S408 is that the propagation loss difference is not within the set value (step S408: NO), the measured value is flagged and recorded (step S412).

  Next, a propagation loss measuring apparatus according to a second embodiment of the present invention will be described with reference to FIG.

  The propagation loss measuring apparatus according to the present embodiment has the same configuration as that of the above-described embodiment except that it is installed in the measurement vehicle 400. In addition, a distance pulse generator 500 connected to the data recording unit 205 is provided.

  On the transmission side, the transmission unit 101, the antenna 102, the transmission unit 103, and the antenna 104 are installed on the steel tower platform 300.

  The transmitter 101 transmits a radio wave having a frequency to be measured of 800 MHz, for example. The transmitter 103 transmits a radio wave having a reference frequency of 8000 MHz, for example.

  The distance pulse generator 500 generates pulses at a predetermined distance, for example, at an interval of 1 cm, according to the traveling of the measurement vehicle 400. The data recording unit 205 samples the reception level obtained from the reception units 201 and 203 in accordance with the distance pulse, and records the average reception level for every fixed distance.

  The calculation unit 206 obtains propagation losses at 800 MHz and 8000 MHz, and obtains a propagation loss difference using the result. Further, it is determined whether or not the obtained propagation loss difference is within a predetermined determination value. If it is within the judgment value, it is recorded as it is, and if it is above the judgment value, the data is recorded with an error flag. Data with an error flag will not be used in the end.

  As described above, according to the embodiment of the present invention, in the propagation loss measurement, by measuring the propagation loss of the reference frequency different from the measured frequency at the same time, whether all the data of the measured frequency is correctly measured. It is possible to check mechanically efficiently and prevent measurement errors. Moreover, since a measurement error can be detected during measurement, a measurement error that temporarily occurs during the measurement can be found.

  In particular, when there are two or more frequencies to be measured, measurement data can be confirmed based on the propagation loss difference between the two frequencies to be measured without preparing a reference frequency.

  Further, in the present embodiment, the case where the propagation loss measuring device is provided in the measurement vehicle has been described, but the mobile station may be provided. In this way, the propagation loss can be easily measured.

  The propagation loss measuring apparatus according to the present invention can be applied to an apparatus that performs radio wave measurement in mobile radio communication.

It is explanatory drawing for demonstrating the method to confirm a measuring device. It is a characteristic view which shows the correlation of the propagation loss of a different frequency. It is a block diagram which shows the propagation loss measuring device concerning one Example of this invention. It is a flowchart which shows operation | movement of the propagation loss measuring device concerning one Example of this invention. It is a block diagram which shows the propagation loss measuring device concerning one Example of this invention.

Explanation of symbols

10 steel tower 20 propagation loss measuring instrument 100 base station 200 propagation loss measuring instrument 300 steel tower platform 400 measuring vehicle

Claims (2)

Receiving means for receiving radio waves having a reference frequency different from the frequency to be measured;
Propagation loss calculating means for calculating propagation loss of radio waves of the reference frequency;
Detection means for detecting a measurement error based on propagation loss of radio waves of the measured frequency and the reference frequency;
A propagation loss measuring apparatus comprising: In the propagation loss measuring device according to claim 1:
Determining means for obtaining a difference between the propagation loss of the radio wave of the frequency to be measured and the propagation loss of the radio wave of the reference frequency, and determining whether the difference satisfies an allowable value;
With
The propagation loss measuring device, wherein the detecting means detects a measurement error based on the determination.

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