JP4074613B2 - CDMA signal analyzer - Google Patents

Description

  The present invention relates to a CDMA signal analyzing apparatus for analyzing a signal in each channel of each spreading factor of a CDMA signal that is an input signal under measurement.

  As one of the wireless communication systems in the third generation mobile communication system, W-CDMA (Wideband Code Division Multiple Access) has been proposed. When this communication method is used, a large number of data transmitted and received according to the W-CDMA communication standard (3GPP) are multiplexed and incorporated in a signal transmitted and received between a base station and a mobile station (mobile phone). It is.

  FIG. 4 shows a multiplexing method of transmission data D0 to Dn on the transmission side in W-CDMA. The transmission data D0 to Dn are phase-modulated by the modulation unit 1 using a modulation scheme such as QPSK, for example, and spread by the spreading unit 2 using different spreading codes (orthogonal variable spreading codes) w0 to wn. Is then multiplied by the scramble code in the scramble circuit 4, converted to a high frequency signal by the high frequency circuit 5 as 3.84 MHz chip data, and output from the antenna 6 as a radio wave.

  Next, the configuration of the spreading code for spreading the transmission data D0 to Dn in the spreading unit 2 will be described with reference to FIG. The spread code of this CDMA system is configured in a tree structure as shown in the figure, and spread code (Spreading Factor) according to the spread code length 4, 8, 16, 32, 64, 128, 256, 512 of the spread code 7, respectively. ) 8 (SF4, SF8, SF16, SF32, SF64, SF128, SF256, SF512) is defined. In FIG. 5, the diffusion factors 8 of SF32 to SF512 are omitted.

  Each spreading factor 8 is assigned a spreading code 7 corresponding to the spreading code length of the spreading code 7 to which it belongs. For example, a total of eight spreading codes 7 each having a code length of 8 for channels CH0 to CH7 are assigned to the spreading factor SF8 according to a certain rule.

  In W-CDMA, the transmission rate of data output from the transmission side is fixed (3.84 Mcps, and the length (time) of one frame is also fixed (10 ms). Therefore, the number of chip data included in one frame is also constant ( Therefore, on the transmission side, the code length (spreading factor 8) of the adopted spread code 7 depends on the number of data to be transmitted and the type of data (information) (alphanumeric data, sound, image etc). ) Is selected and set.

  In this case, all the spreading codes 7 belonging to the lower spreading factor 8 branched (branched) from the selected spreading code 7 and each spreading code 7 of the higher sequence of the selected spreading code 7 are prohibited from being selected. Become. This is because when the spreading code 7 of the lower spreading factor 8 branched from itself or the spreading code 7 of the upper sequence of the own is simultaneously selected, which spreading code 7 is despread. This is because it is not possible to distinguish whether the transmission data is spread by the.

  Therefore, the maximum number of spreading codes 7 that can be adopted by the spreading unit 2 in the spreading code group configured in this tree structure is 512.

  Each transmission data D0 to Dn on the transmission side in W-CDMA is modulated by a modulation unit 1 using a modulation scheme of QPSK (Quadrature phase shift keying four phase shift keying). Further, in recent years, a standard of HSDPA (High Speed Downlink Packet Access) of the 3.5th generation mobile communication system (3.5G) that has increased the packet communication speed based on the W-CDMA has been studied. In this HSDPA, each transmission data D0 to Dn can adopt a modulation method of 16QAM (Quadrature amplitude modulation) in addition to QPSK.

  Therefore, it is necessary to test that the radio wave signal transmitted from the base station to each mobile station (mobile phone) in the mobile communication system adopting such a W-CDMA wireless communication system satisfies the above-mentioned standard. is there.

Patent Document 1 discloses a technique for determining the code domain power of each channel in a CDMA signal and identifying the channel to which each transmission data is allocated (adopted) on the base station side.
JP 2000-36802 A

  Therefore, in the third generation mobile communication system adopting the W-CDMA standard and the 3.5th generation mobile communication system adopting the HSDPA standard, radio waves transmitted from the base station to each mobile station (mobile phone) It is desired to develop a CDMA signal analysis apparatus that can easily verify that a signal satisfies the above-mentioned standard.

  The characteristics of each channel in the CDMA signal include, in addition to the above-described code domain power, the presence / absence of a signal, the modulation method when there is a signal, constellation, modulation accuracy [EVM (Error Vector Magnitude), amplitude error, phase error] , Origin offset], error rate (BER Bit Error Ratio), and the like.

  The above-described characteristics affect each other. Then, when an abnormal value occurs in one characteristic, it is investigated whether an abnormality has occurred in other characteristics related to this characteristic, and the occurrence state of each abnormality is analyzed to investigate the cause of the abnormality. It is desirable.

  In particular, the code domain power of each channel in the CDMA signal changes in power value according to the distance to each mobile station (mobile phone) of the communication destination for each channel, so that an abnormality occurs depending on the magnitude of the power value. Cannot judge immediately.

  However, in Patent Document 1 described above, the code domain power of each channel in the CDMA signal is obtained and displayed as a code domain power characteristic on the display. However, characteristics other than the code domain power of each channel are as follows. Not seeking. Therefore, when an abnormality occurs, it is difficult to efficiently investigate the cause of the abnormality in a short time from only the code domain power value of each channel.

  The present invention has been made in view of the above circumstances, and in addition to the code domain power of each channel in the CDMA signal, the code domain error of each channel is also measured, so that it is graphically displayed on the display. It is an object of the present invention to provide a CDMA signal analyzing apparatus that can grasp at a glance a channel where an abnormality has occurred from the code domain power characteristics and can efficiently investigate the cause of the abnormality in a short time.

  The present invention is applied to a CDMA signal analyzing apparatus that analyzes a signal in each channel of each spreading factor of a CDMA signal that is an input signal under measurement.

And in order to eliminate the subject mentioned above, in the CDMA signal analyzer of this invention, it output from the input processing part which produces the chip data from which the frame synchronization was taken from the input to-be-measured signal, and was output from the input processing part The chip data is despread with a spreading code corresponding to the spreading factor for each channel and output as symbol data of each channel, and the symbol data of each channel output from the despreading processor is used to Code domain power calculation unit that calculates the code domain power of the channel, and power characteristic display that graphically displays the code domain power of each channel calculated by the code domain power calculation unit on the display as code domain power characteristics Means and symbol data of each channel output from the despreading processing unit A code domain error calculation unit for calculating the code domain error of each channel, and a code domain exceeding a preset threshold among the code domain errors of each channel calculated by this code domain error calculation unit Corresponds to the channel of the code domain error specified by the threshold judgment part of the code domain power of each channel in the code domain power characteristics displayed on the display and the threshold judgment part to specify the error A power emphasis display means for emphasizing the code domain power of the channel to be used, a modulation method determination unit for determining the modulation method of each channel using the symbol data of each channel output from the despreading processing unit, and this modulation The modulation method of each channel determined by the method determination unit is displayed as a list of modulation methods. And a modulation method display means for displaying on the display unit in correspondence with each channel of the indicated code domain power characteristics.

  In the CDMA signal analyzing apparatus configured as described above, in addition to the code / domain power calculation unit for calculating the code / domain power of each channel, a code / domain error calculation unit for calculating the code / domain error of each channel is provided. ing. Further, a threshold judgment unit is provided for designating a code domain error exceeding the threshold. Then, the code domain power whose error in the displayed code domain power characteristic exceeds the threshold value is highlighted.

Therefore, from the displayed code domain power characteristics, it is possible to understand the channel where the error occurred (error exceeded the threshold) and the relationship between the channel where the error occurred and the code domain power of the corresponding channel, and the cause of the error. Can be investigated efficiently in a short time.
In addition, since the modulation method of each channel is displayed on the display as a list of modulation methods, it is possible to grasp at a glance whether the difference in code domain error between channels is due to the modulation method. The occurrence status can be grasped more accurately.

  Another invention provides the CDMA signal analyzing apparatus according to the invention described above, and further displays the code domain error of each channel calculated by the code domain error calculation unit as a code domain error characteristic to the display. On the same screen as the code domain power characteristic, the error characteristic display means for graphic display, and the threshold value judgment unit of the code domain error of each channel in the code domain error characteristic displayed on the display Error highlighting means for highlighting a specified code domain error.

  In the CDMA signal analyzing apparatus configured as described above, the code domain error characteristic is displayed on the same screen in addition to the code domain power characteristic described above on the display. Further, in this code domain error characteristic, a code domain error exceeding a threshold value is highlighted. Therefore, it is possible for a tester who performs a test using this CDMA signal analyzing apparatus to grasp the abnormality occurrence state more accurately.

  According to the present invention, in addition to the code domain power of each channel in the CDMA signal, the code domain error of each channel is also measured, and the error in the code domain power characteristic displayed on the display exceeds a threshold value. Code domain power is highlighted.

  Therefore, it is possible for a tester who performs a test using a CDMA signal analyzer to grasp the channel where an error has occurred from the code domain power characteristics displayed on the display device, and to efficiently determine the cause of the error in a short time. Can be investigated.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a block diagram showing a schematic configuration of a CDMA signal analyzing apparatus according to an embodiment of the present invention.

  In the CDMA signal analyzing apparatus of this embodiment, a signal under measurement a that employs an HSDPA communication method output from a base station is input. As described with reference to FIG. 4, the signal under measurement a adopting this HSDPA communication method is obtained by modulating each transmission data D0 to Dn by each modulation unit 1 using a QPSK or 16QAM modulation method. Each code is spread by each spreading code 7 having the standard shown in FIG. 5, added by the adder 3, scrambled by the scramble circuit 4, converted into a high frequency signal by the high frequency circuit 5, and output from the antenna 6. One signal.

  The signal under measurement a input to the CDMA signal analyzing apparatus in FIG. 1 is frequency-converted to an intermediate frequency based on the frequency signal from the local oscillator (LOOSC) 12 by the frequency converter 11 in the input processor 10. Thereafter, the A / D converter 13 performs A / D conversion. The A / D converted digital measured signal a is quadrature demodulated into an I (in-phase) component and a Q (quadrature) component by the I and Q separation unit 14 and input to the detection unit 15. The detection unit 15 detects the I component and the Q component by the clock extracted by the clock extraction unit 16 to the data I and Q in units of chips and sends them to the next frequency correction unit 17.

  The frequency correction unit 17 uses the carrier extracted by the carrier extraction unit 18 to correct the frequency error at the time of conversion to the intermediate frequency. The data I and Q in units of chips whose frequency error is corrected are de-scrambled by multiplying the descrambling code described above by the next descrambling unit 19, and new frame-synchronized data is obtained from the input processing unit 10. Is input to the despreading unit 20 as correct chip data I and Q.

  The despreading unit 20 despreads the input chip data I and Q with each spreading code 7 having different spreading factors 8 shown in FIG. 5 to obtain a plurality of symbol data, and a spreading factor (spreading factor). 8) Send to determination unit 21. The spreading factor determination unit 21 determines the channel (code) of each symbol data from the spreading factor 8 and the spreading code 7 of the plurality of input symbol data, and the channels 1 to channels corresponding to the transmission data D0 to Dn. The data is output as symbol data 23 indicated by I and Q values for each of the n channels.

  Therefore, the despreading unit 20 and the spreading factor determination unit 21 despread the chip data output from the input processing unit 10 with the spreading code 7 corresponding to the spreading factor 8 for each channel, and output it as symbol data 23 for each channel. The despreading processing unit 22 is configured.

  The symbol data 23 of each channel 1 to channel n output from the despreading processing unit 22 is sent to the code / domain power calculation unit 24 and the modulation scheme determination unit 26.

  The code domain power calculation unit 24 calculates the power P (code domain power) of the symbol data 23 indicated by the input I and Q values of each channel. Specifically, as shown in FIG. 2, the code domain power P of a certain code (channel) displays symbol data I (in-phase component) and Q (quadrature component) of the corresponding code (channel) on the IQ coordinate. In this case, the total value of the powers p1 to pn of all the channels (codes) from channel 1 to channel n of the power p indicated by the square value of the measurement vector Z, which is a vector from the coordinate origin (p1 + p2 + ... + pn) It is shown as a ratio to.

p = Z ² = I ² + Q ²
P = 10 · log [p / (p1 + p2 + ... + pn)] (dB)
The code / domain power calculation unit 24 sends the calculated code / domain power P of each channel to the threshold value determination unit 27. The threshold determination unit 27 determines whether or not the code domain power P of each channel is equal to or greater than a threshold Ph for determining the presence or absence of a signal of the corresponding channel, and the code domain power equal to or greater than the threshold Ph P is sent to the display control unit 29 as the normal code domain power P. The threshold determination unit 27 determines that the code domain power P less than the threshold Ph is noise, and thereafter treats it as “no signal”.

  Further, the threshold determination unit 27 sends the determination result of the presence / absence of the signal of each channel to the code / domain error calculation unit 25 and the modulation scheme determination unit 26.

  Then, the display control unit 29 sets the code domain power characteristics 31 of the n channels together with the threshold value Ph used to determine the presence or absence of the signal, as shown in FIG. As a graphic display.

  Next, the definition and calculation method of the code domain error CDE of each code (channel) will be described with reference to FIG.

  The vector from the coordinate origin of the measurement point when the symbol data I (in-phase component) and Q (quadrature component) are displayed on the IQ coordinate is the measurement vector Z, and the vector of the ideal point where the input symbol data should be originally Is an ideal vector R. A vector from the ideal point to the measurement point is defined as an error vector E.

Error vector E = | Z−R |
The EVM (Error Vector Magnitude), which constitutes the modulation accuracy together with the amplitude error, phase error, and origin offset described above, is defined by the following equation using each time RMS (square mean value) of the error vector E and the ideal vector R. Has been.

EVM = [RMS (E) / RMS (R)] × 100 (%)
In the CDMA signal analysis apparatus shown in FIG. 1, the ideal vector R is created from the symbol data 23 of n channels output from the despreading processing unit 22, and the measurement vector Z and the error vector E are output from the frequency correction unit 17. Is generated from the data I and Q in units of chips before descrambling.

  Therefore, in order to divide the error vector E for each code (channel), it is necessary to descramble the error vector E and to perform code despreading. Here, the unscrambled error vector E is used as a new error vector Ea, and is despread with each spreading code S. The error vector for each code (channels 1 to n) is further converted into a new error vector Eb (= Eb1, Eb2,..., Ebn).

  The RMS value of the error vector Eb of each code (channel) is referred to as code EVM.

Code EVM = RMS (Eb)
The code domain error CDE of each code (channel) is CDE = 10 · log [(RMS (Eb)) ² / (RMS (R)) ² ] (dB)
It becomes.

  Next, a method for calculating the ideal vector R will be described. The n-channel symbol data 23 output from the despreading processing unit 22 in FIG. 1 is input to the ideal signal generation unit 41 of the ideal signal generation unit 40. The ideal signal generator 41 averages the symbol data 23, for example, and determines the ideal symbol data by taking this average into consideration. The ideal symbol data is diffused by the diffusion processing unit 42 and further scrambled by the scramble processing unit 43 to obtain one ideal vector R. The ideal signal generation unit 40 sends the created ideal vector R to the code / domain error calculation unit 25 and also sends it to the optimization unit 44 and the error signal creation unit 45.

  Next, a method of calculating the measurement vector Z, the error vector E, and the error vector Eb of each code (channel) will be described. The data I and Q in units of chips output from the frequency correction unit 17 in FIG. 1 before descrambling is input to the optimization unit 44. The optimization unit 44 adjusts the frequency and phase of the data I and Q, the gain and timing of each code channel so that the EVM of the data I and Q is minimized, and adjusts the data I and Q after adjustment. Let Q be a measurement vector Z as an optimization signal. The error signal generator 45 calculates an error vector E from the input measurement vector Z and the ideal vector R input from the ideal signal generator 40 (E = | Z−R |).

  The descrambling unit 46 descrambles the error vector E and sends it to the despreading unit 47 as a new error vector Ea. The despreading unit 47 despreads the error vector Ea after descrambling with each spreading code S to obtain an error vector Eb (= Eb1, Eb2,..., Ebn) for each code (channels 1 to n), It is sent to the code / domain error calculation unit 25.

  The code / domain error calculation unit 25 calculates a code EVM for each code (channels 1 to n) from the error vector Eb for each code (channels 1 to n), and further calculates the code EVM for each code (channels 1 to n). The calculated code domain error CDE is calculated.

  Actually, the code domain error calculation unit 25 receives the symbol data of each channel, which is input from the despreading processing unit 22 and is determined to have a signal from the threshold determination unit 27 among the symbol data 23 of n channels. 23 code domain error CDE is calculated.

  The code domain error calculation unit 25 sends the calculated code domain error CDE of each channel with a signal to the threshold value determination unit 28.

  The threshold determination unit 28 determines whether or not the code domain error CDE of each channel with an input signal is greater than or equal to a preset threshold Eh, and the code of each channel with an input signal The determination information described above is added to the domain error CDE and sent to the display control unit 29.

  The display control unit 29 graphically displays the code domain error CDE of each channel with a signal input from the threshold determination unit 28 as a code domain error characteristic 32 on the display 30 as shown in FIG. To do. In this case, the code domain error 33 equal to or higher than a preset threshold value Eh is highlighted with a different color, for example.

  Further, the display control unit 29 has a code domain error characteristic 32 out of the code domain power P of each channel in the code domain power characteristic 31 displayed on the display 30, which is equal to or higher than a preset threshold value Eh. The code domain power 34 of the channel corresponding to the code domain error 33 is highlighted in a different color, for example.

  The modulation scheme determination unit 26 receives the QPSK or 16QAM of the symbol data 23 of each channel determined to have a signal from the threshold determination unit 27 out of the n channel symbol data 23 input from the despreading processing unit 22. Determine the modulation method. Specifically, the constellation of the symbol data 23 indicated by the input I and Q values of each channel is obtained, and the QPSK or 16QAM modulation system of each channel is determined from the constellation pattern. The modulation method determination unit 26 sends the determined QPSK or 16QAM modulation method of each channel to the display control unit 29.

  The display control unit 29 displays and outputs the QPSK or 16QAM modulation schemes of each channel as a modulation scheme list 35 on the display 30 as shown in FIG.

  In the CDMA signal analyzing apparatus configured as described above, as shown in FIG. 3, the code / domain error characteristic 32, the code / domain power characteristic 31, and the modulation scheme list 35 are simultaneously displayed on the display 30.

  In the code domain power characteristic 31, the code domain power P of n channels from channel 1 to channel n is displayed at the same time as the threshold value Ph. Therefore, a test using this CDMA signal analyzing apparatus is performed. The practitioner can grasp the presence / absence of signals of each channel at a glance.

  Further, in the code domain error characteristic 32, only the code domain error CDE of the channel with the signal is displayed. It is meaningless to calculate and display the code domain error CDE of the channel without signal. Therefore, no unnecessary judgment is imposed on the tester. Further, since the code domain error 33 exceeding the preset threshold Eh is highlighted, the tester can grasp the channel of the code domain error 33 above the threshold Eh at a glance.

  Further, in the code domain power characteristic 31, the code domain power 34 of the channel corresponding to the code domain error 33 that is greater than or equal to a preset threshold value Eh that has a high possibility of occurrence of an abnormality is highlighted. As described above, since the code domain power P of each channel varies depending on the distance to each communication destination mobile station (mobile phone) for each channel, the code domain power P depends on the magnitude of the code domain power P. Therefore, it is impossible to immediately determine whether an abnormality has occurred. Therefore, by highlighting the code domain power 34 having a high possibility of occurrence of an abnormality, for example, the code domain power P is sufficiently large as shown in the left side code domain power 34 in FIG. The practitioner can grasp at a glance new knowledge that there is a channel with a high possibility of occurrence of an abnormality.

  Further, a modulation scheme list 35 is displayed on the display 30. In general, if the modulation method is different, the code domain error CDE also changes. The code domain error CDE of the 16QAM modulation scheme is larger than the code domain error CDE of the QPSK modulation scheme. Therefore, it is possible to grasp at a glance whether or not the variation of the code domain error CDE between the channels in the code domain error characteristic 32 is caused by the modulation method.

1 is a block diagram showing a schematic configuration of a CDMA signal analyzing apparatus according to an embodiment of the present invention. The figure which shows the calculation method of the code domain error in the CDMA signal analysis apparatus of the embodiment The figure which shows the display content of the indicator in the CDMA signal analysis apparatus of the embodiment The figure which shows the multiplexing method of each transmission data of the transmission side in general W-CDMA Diagram showing the relationship between the spreading factor set in the tree structure and the spreading code in each channel

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Modulation part, 2 ... Spreading part, 3 ... Adder, 4 ... Scramble circuit, 5 ... High frequency circuit, 6 ... Antenna, 7 ... Spreading code, 8 ... Spreading factor, 10 ... Input processing part, 11 ... Frequency conversion part , 13 ... A / D conversion section, 14 ... I, Q separation section, 19 ... descrambling section, 22 ... despreading processing section, 23 ... symbol data, 24 ... code domain power calculation section, 25 ... code domain error Calculation unit, 26 ... Modulation method determination unit, 27, 28 ... Threshold determination unit, 29 ... Display control unit, 30 ... Display, 31 ... Code domain power characteristic, 32 ... Code domain error characteristic 32, 35 ... List of modulation methods, 40 ... ideal signal generator, 44 ... optimizer, 45 ... error signal generator

Claims (2)

In a CDMA signal analyzing apparatus for analyzing a signal in each channel of each spreading factor of a CDMA signal that is an input signal under measurement,
An input processing unit (10) for creating chip data with frame synchronization from the input signal under measurement;
A despreading processing unit (22) for despreading the chip data output from the input processing unit with a spreading code corresponding to a spreading factor for each channel and outputting as symbol data of each channel;
A code domain power calculation unit (24) for calculating code domain power of each channel using the symbol data of each channel output from the despreading processing unit;
Power characteristic display means (29) for graphically displaying the code domain power of each channel calculated by the code domain power calculation unit on the display as a code domain power characteristic (31);
A code domain error calculation unit (25) for calculating a code domain error of each channel using the symbol data of each channel output from the despreading processing unit;
A threshold determination unit (28) for designating a code domain error exceeding a preset threshold among the code domain errors of each channel calculated by the code domain error calculation unit;
Emphasize the code domain power of the channel corresponding to the channel of the code domain error specified by the threshold judgment unit among the code domain power of each channel in the code domain power characteristic displayed on the display Power highlighting display means (29) for displaying;
A modulation method determination unit (26) for determining the modulation method of each channel using the symbol data of each channel output from the despreading processing unit;
Modulation method display means for displaying the modulation method of each channel determined by the modulation method determination unit on the display unit as a modulation method list (35) corresponding to each channel of the code-domain power characteristics displayed graphically (29) A CDMA signal analyzing apparatus comprising: The code domain error calculated by the code domain error calculation unit is displayed as a code domain error characteristic (32) on the same screen as the code domain power characteristic on the display. Error characteristic display means (29) for
Error emphasis display means (29) for emphasizing the code domain error designated by the threshold value determination unit among the code domain errors of each channel in the code domain error characteristic displayed on the display unit. The CDMA signal analyzing apparatus according to claim 1, further comprising:

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