JP2012195895A - Fading simulator, mobile communication terminal test system, and fading processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To settle a level of fading signals within a desired range.SOLUTION: A fading simulator includes: an operation core unit for receiving a plurality of digital baseband signals inputted at a first level P, executing fading processing, compositing output and outputting it as digital fading signals; an output level adjusting unit for changing the level of the fading signals on the basis of a prescribed gain G; an output level measuring unit for measuring a second level Pof the fading signals whose level has been changed, when there are correlation characteristics between the respective baseband signals or between respective propagation paths; and an output level adjustment control unit for calculating a level ratio K of the first level Pand the second level P, and updating the gain Gso that the level ratio K becomes a prescribed value, when there are the correlation characteristics between the respective baseband signals or between the respective propagation paths.

Description

  The present invention relates to a technique for fading processing that simulates fading caused by spatial propagation between a mobile communication terminal and a base station, and more particularly to a technique for adjusting a signal level after fading processing.

  There is a fading simulator that generates a signal that simulates fading caused by spatial propagation between a mobile communication terminal and a base station (hereinafter sometimes referred to as a “fading signal”). A signal for wireless communication is generally transmitted by a carrier wave modulated with a desired signal in a baseband. As a method of simulating fading, there are a method of performing fading processing on a baseband signal and a method of performing fading processing on a carrier wave. With the recent increase in frequency and bandwidth of signals, a method of performing fading processing on baseband signals is often used because the signals can be controlled digitally. An example of such a fading simulator is disclosed in Patent Document 1.

  On the other hand, in mobile communication terminals represented by mobile phones and the like, information from the Internet is often downloaded, and the amount of downlink information transmission is increasing. However, widening the frequency band in order to increase the amount of information decreases the number of terminals that can communicate and does not increase the amount of information transmitted as a whole system. As one method for solving this problem, a multiple input multiple output (MIMO) method has been proposed.

  In the MIMO system, information to be transmitted to a mobile communication terminal on the base station side is simultaneously output from a plurality of “M” antennas at the same frequency, and the mobile communication terminal receives the information from a plurality of “N” antennas. Information separation processing is performed inside the communication terminal. Thereby, the MIMO system can improve the amount of information transmission.

  The number of propagation paths constituting the MIMO corresponds to the number of combinations of the number “M” of antennas on the base station side and the number “N” of antennas on the mobile communication terminal side. In a fading simulator that assumes a mobile communication system that employs a MIMO scheme, a fading signal is generated by performing a fading process in accordance with a propagation path on each baseband signal for a plurality of generated baseband signals. At this time, the fading signal is generated by adding a plurality of baseband signals subjected to fading processing. Therefore, the fading simulator adjusts and outputs the level of the fading signal, which is increased by superimposing the baseband signals, to a predetermined level. Examples of the predetermined level include a value obtained by adjusting the level of the baseband signal based on the gain designated by the operator.

  In an example of a conventional fading simulator, the operation is performed assuming that there is no correlation between baseband signals. When there is no correlation between the baseband signals, the theoretical value of the fading signal level can be calculated in advance based on the level of each baseband signal. Therefore, an example of a conventional fading simulator determines the gain of the fading signal level based on the theoretical value of the fading signal level.

  However, when there is a correlation between the baseband signals, the level of the fading signal varies depending on the fading processing conditions (for example, the phase difference), and the theoretical value is not uniquely determined. Therefore, it is difficult to calculate the level of the fading signal from the level of each baseband signal. Similarly, when there is a correlation between the propagation paths for which fading conditions are set, it is also difficult. Therefore, in these cases, the conventional fading simulator cannot change the gain according to the level of the fading signal, and it is difficult to keep the output level constant with high accuracy.

JP 2010-98650 A

  An object of the present invention is to keep the level of a fading signal within a desired range.

In order to achieve the above-mentioned object, the invention according to claim 1 receives a plurality of (m) baseband signals for testing a mobile communication terminal inputted at a first level _PIN , and An arithmetic core that includes a plurality of arithmetic core units (231X _{1 to} 231X _m ) that perform a fading process on a band signal, synthesizes outputs of the plurality of arithmetic core units, and outputs a digital fading signal for each propagation path of mobile communication and part group, a fading simulator where the output level adjustment section (235), equipped with changing the level of the fading signal based on the gain G _C previously determined, there is the correlation characteristics between the baseband signal Or when there is a correlation characteristic between the propagation paths, the level of the fading signal whose level has been changed is defined as a second level P _OUT . The first level _PIN and the second level when the correlation characteristic is present between the output level measurement unit (236) to measure and the baseband signal or when there is a correlation characteristic between the propagation paths. calculating a level ratio K between the level P _OUT of a feature in that it comprises as the level ratio K becomes a predetermined value, the output level adjustment control unit configured to update the gain G _C (24), the It is a fading simulator.
The invention according to claim 2 is the fading simulator according to claim 1, further comprising a correlation characteristic detection unit (222) for detecting presence or absence of correlation characteristics between the plurality of baseband signals. Features.
The invention according to claim 3 is the fading simulator according to claim 1 or 2, wherein the input level measuring unit obtains the first level _PIN by measuring the level of the baseband signal. (221), and the output level adjustment control unit calculates the level ratio K based on a measurement result (P _IN ) of the input level measurement unit.
The invention according to claim 4 is the fading simulator according to any one of claims 1 to 3, wherein the arithmetic core unit group, the plurality of (m) baseband signals, A plurality of (n) sets of level adjustment units and output level measurement units are provided, and a plurality of different fading signals are output.
The invention according to claim 5 is the fading simulator according to any one of claims 1 to 4, wherein the display unit (28) and display control for displaying the level ratio K on the display unit. Part (26).
The invention according to claim 6 is the fading simulator according to any one of claims 1 to 5, wherein the level ratio K does not become the predetermined value during a predetermined period. It is a feature that a notification to that effect is given.
According to a seventh aspect of the present invention, there is provided a baseband signal generation unit (11) for generating a plurality of (m) digital baseband signals for testing having a first level _PIN as an output level; A fading simulator (20) that outputs a plurality (n) of fading signals according to the propagation path that constitutes the MIMO, and converts each fading signal output from the fading simulator into an analog signal And a transmission unit (12) that performs frequency conversion according to a predetermined communication method and outputs the result to a mobile communication terminal that is a test target, wherein the fading simulator includes the plurality of basebands receiving a signal, the baseband signal subjected to the fading process operation core section (231X ₁ to 2 Includes a plurality of 1X _m), the plurality of processor cores unit group for outputting the output of the arithmetic core section as a composite digital fading signal for each of the propagation path, the fading signal based on the gain G _C determined in advance When there is the correlation characteristic between the output level adjustment unit (235) that changes the level and the baseband signal, or when there is a correlation characteristic between the propagation paths, the level of the fading signal whose level has been changed When there is a correlation characteristic between the output level measurement unit (236) that measures the second level P _OUT and the baseband signal, or when there is a correlation characteristic between the propagation paths, the first level P the ratio of the the _iN second level P _OUT is calculated as a level ratio K, as the level ratio K becomes a predetermined value, further the gain G _C Output level adjustment control unit to (24), a mobile communication terminal testing system comprising the.
The invention according to claim 8 is the mobile communication terminal test system according to claim 7, wherein the fading simulator performs the operation core unit group on the plurality (m) of baseband signals. A plurality of (n) sets of the level adjusting unit and the output level measuring unit are provided, and a plurality of different fading signals are output.
The invention according to claim 9 receives a plurality of baseband signals for testing the mobile communication terminal input at the first level _PIN , and outputs a fading signal for each propagation path of mobile communication. A fading processing method using a fading simulator (20) that detects the presence or absence of correlation characteristics between the plurality of baseband signals and the presence or absence of correlation characteristics between the propagation paths a characteristics detecting step, subjected to a fading process on the plurality of baseband signals, to change the fading process step of outputting a fading signal by combining the output, the level of the fading signal based on the gain G _C determined in advance When there is the correlation characteristic between the level adjustment step and the baseband signal, or between the propagation paths If there is a correlation characteristic, and a second measuring step of measuring the level of the fading signal level is changed as the second level P _OUT, when there is the correlation characteristics between before the baseband signal, or the When there is a correlation characteristic between the propagation paths, a level ratio K between the first level P _IN and the second level P _OUT is calculated, and the gain is set so that the level ratio K becomes a predetermined value. a gain adjusting step of updating the G _C, a fading processing method comprising the.

  The fading simulator according to the present invention calculates a level ratio based on a baseband signal level and a fading signal level when there is a correlation between baseband signals or when there is a correlation characteristic between the propagation paths. The level of the fading signal is adjusted so that the level ratio becomes a predetermined value. As a result, the fading simulator according to the present invention can keep the level of the fading signal within a predetermined range when there is a correlation between baseband signals or when there is a correlation characteristic between the propagation paths. Become.

It is a block diagram which shows the structure of embodiment of this invention. It is a block diagram of the fading calculating part which concerns on embodiment of this invention. It is a block diagram of the calculation core part which concerns on embodiment of this invention. It is a flowchart of the process which concerns on specification of the adjustment method of a level. It is a flowchart of the process which concerns on the level adjustment of a fading signal.

  An embodiment of the present invention will be described with reference to FIG. The fading simulator according to the present embodiment is applied to the mobile communication terminal test system 1 shown in FIG.

  The mobile communication terminal test system 1 generally transmits a carrier wave obtained by frequency-converting a baseband signal based on a predetermined communication method from a transmission unit of a pseudo base station apparatus to the terminal under test. Test reception characteristics. Further, the mobile communication terminal test system 1 receives a signal transmitted from the terminal under test by the receiving unit of the pseudo base station apparatus and tests the transmission characteristics of the terminal under test. The fading simulator is connected to the configuration on the transmission side of the pseudo base station apparatus, and performs fading processing on the signal generated for the test. In the following, description will be given focusing on the configuration for transmitting a carrier wave to the terminal under test.

  The mobile communication terminal test system 1 includes a base station simulation device 10 and a fading simulator 20 attached to the base station simulation device 10. The base station simulation device 10 is configured to be able to communicate with the terminal under test 2 wirelessly or by wire. Note that the base station simulator 10 and the fading simulator 20 may be provided in the same casing.

  The base station simulation device 10 includes a baseband signal generation unit 11 and a transmission unit 12. The fading simulator 20 is connected between the baseband signal generation unit 11 and the transmission unit 12. The fading simulator 20 includes a fading calculation unit 21, a setting control unit 25, a display control unit 26, an operation unit 27, and a display unit 28.

First, an outline of the operation of the fading simulator 20 will be described. The fading simulator 20 receives a predetermined number “m” of baseband signals from the baseband signal generation unit 11, performs fading processing on these baseband signals, and is determined in advance according to the propagation path constituting the MIMO. The number “n” of fading signals are output to the transmitter 12. In the following description, it is assumed that fading simulator 20 receives baseband signals X _{1 to} X _m and outputs fading signals Y _{1 to} Y _n .

The fading simulator 20 according to the present embodiment makes it possible to adjust the output level for each output fading signal (Y _{1 to} Y _n ), and provides gains G _{O1 to} G _On as parameters therefor. Here, the gain G _O1 corresponds to the fading signal Y ₁ , and the gain G _On corresponds to the fading signal Y _1n . The operator designates the output level of each fading signal by setting the gains G _{O1 to} G _On via the operation unit 27. Taking the fading signal Y ₁ as an example, the fading simulator 20 operates the fading computing unit 21 so that the level of the fading signal Y ₁ is equal to the level of the baseband signal X ₁ adjusted by the gain _{GO 1} . The operation of the fading calculation unit 21 will be described later.

Further, the fading signal _Y 1 to Y _n, since a plurality of signal fading-processed for each of the plurality of baseband signals _X 1 to X _m is one that is superimposed, from the baseband signal _X 1 to X _m May also increase the output level. Therefore, the fading simulator 20, the gain _{G C} for adjusting the level of the fading signal _Y 1 to Y _n are provided. Fading simulator 20 is allowed to output attenuates the fading signal _Y 1 to Y _n by the gain _{G C.} It will be described later in detail gain G _C. Further, in the following, a fading signal before level by the gain G _C is adjusted is referred to as "fading signal Z ₁ to Z _n", "fading signal Y ₁ to Y _n" is the level is adjusted by a gain G _C It shall refer to the fading signal after.

Further, the fading simulator 20 is provided with two modes of “fixed gain adjustment” and “automatic gain adjustment” as adjustment methods (modes) of the levels of the fading signals Y _{1 to} Y _n . "Fixed gain adjustment" is a mode using a fixed value determined in advance as the gain G _C. Further, "automatic gain control" based on the output of the fading signal Y ₁ to Y _n, a mode in which the fading simulator 20 to adjust the gain G _C. Specific operations relating to the specification of the level adjustment method will be described later.

Next, the operation of each component will be described. The baseband signal generation unit 11 generates test baseband signals X _{1 to} X _m indicating the same output level. The baseband signal generation unit 11 outputs the generated baseband signals X _{1 to} X _m to the fading calculation unit 21. Note that, when the fading simulator 20 is not connected to the base station simulator 10 (in other words, when operating as a general pseudo base station as described above), the baseband signal generation unit 11 performs the baseband signals X _{1 to} X _m is output to the transmitter 12.

The setting control unit 25 receives from the operation unit 27 a fading process condition designated by the operator (hereinafter may be referred to as a “fading condition”). The fading conditions include a parameter indicating “level adjustment method”, “multipath presence / absence”, “delay”, “attenuation”, and “noise” conditions, a parameter indicating “Doppler frequency”, and the gain described above. G _{O1 to} G _On are included. Further, the setting control unit 25 determines “presence / absence of correlation between propagation paths” based on these parameters and sets them as new parameters. Whether or not there is a correlation between the propagation paths is determined by, for example, how noise is applied in the fading process. In other words, the setting control unit 25 determines that there is no correlation between the propagation paths when all the propagation paths are Rayleigh fading and the correlation coefficient is 0. The setting control unit 25 determines that there is a correlation between the propagation paths when at least one propagation path is not Rayleigh fading or when the correlation coefficient is not 0. The setting control unit 25 outputs these parameters to the fading calculation unit 21.

Reference is now made to FIG. FIG. 2 shows a block diagram of the fading calculation unit 21. The fading calculation unit 21 includes an input level measurement unit 221, a correlation characteristic detection unit 222, a plurality of fading signal generation units 23Y _{1 to} 23Y _n, and an output level adjustment control unit 24. The fading signal generators 23Y _{1 to} 23Y _n are provided for each fading signal. In the following, the fading signal generator 23Y ₁ corresponds to the fading signal Y _1, fading signal generation unit 23Y _n is described as being provided corresponding to the fading signal Y _n.

The baseband signals X _{1 to} X _m output from the baseband signal generation unit 11 are input to the input level measurement unit 221, the correlation characteristic detection unit 222, and the fading signal generation units 23Y _{1 to} 23Y _n .

Input level measurement unit 221, from the baseband signal generation unit 11 receives the baseband signal _X 1 to X _m of the same level, measuring the level of the baseband signal _X 1 to X _m as the input level _{P IN.} At this time, the input level measuring unit 221 measures any one of the baseband signals X _{1 to} X _m , for example, the level of the baseband signal X _m and sets this as the input level _PIN .

The measurement period T is determined by any one of [a] to [d] shown below.
[A] A value based on the period of the sampling signal of the fading simulator 20.
[B] A value based on the fading condition set in the fading simulator 20.
[C] Value based on communication conditions.
[D] A value empirically determined by experimental measurement in advance.

  In the case of [a], a period that is an integral multiple (for example, 10,000 to 100,000) of the period of the sampling signal of the fading simulator 20 is set as the measurement period. In the case of [b], for example, a period that is an integral multiple (for example, 10 times) of the reciprocal of the Doppler frequency set as the fading condition is set as the measurement period. In the case of [c], for example, an integral multiple (for example, 10 times) of a period corresponding to the frame length or slot length is set as the measurement period. Further, only one of the periods [a] to [d] may be specified as the measurement period, or each of the periods [a] to [d] may be specified, and the longest period among them may be set as the measurement period. Also good.

The input level P _IN is also expressed as a function that integrates X _m (t) X _m ^* (t) for a predetermined measurement period T. Here, X _m (t) indicates the level of the baseband signal X _m at time t. X _m ^* (t) represents the conjugate complex number of X _m (t).

The input level measurement unit 221 outputs the measured input level _PIN to the output level adjustment control unit 24. The output level adjustment control unit 24 will be described later. Further, the input level measurement unit 221 outputs the input level _PIN to the display control unit 26. The display control unit 26 will be described later.

The correlation characteristic detector 222 detects correlation characteristics between the baseband signals X _{1 to} X _m . Hereinafter, a specific method for detecting the correlation characteristic by the correlation characteristic detection unit 222 will be described. The correlation characteristic detection unit 222 accumulates the correlation characteristic R _ij between the baseband signal X _i and the baseband signal X _j by X _i (t) X _j ^* (t) for a predetermined measurement period T. (X ₁ ≦ X _i , X _j ≦ X _m , X _i ≠ X _j ). The measurement period T is the same as the measurement period T of the input level _PIN .

When the calculated correlation characteristic R _ij is less than a predetermined value (ideally, when R _ij = 0), the correlation characteristic detection unit 222 performs a correlation between the baseband signals X _i and X _j. Is determined to have no correlation. Further, the correlation characteristic detection unit 222 determines that there is a correlation between the baseband signals X _i and X _j when the correlation characteristic R _ij is equal to or greater than a predetermined value.

Note that the correlation characteristic detector 222 calculates only one of the correlation characteristics R _ij and R _ji as the correlation characteristic between the baseband signal X _i and the signal X _j and determines the presence or absence of correlation. At this time, X _i (t) X _j ^* (t) and X _j (t) X _i ^* (t) are in a complex conjugate relationship.

In this way, the correlation characteristic detection unit 222 determines the presence or absence of correlation for all combinations of the baseband signals X _{1 to} X _m . When it is determined that there is no correlation for all the combinations, the correlation characteristic detection unit 222 notifies the output level adjustment control unit 24 that there is no correlation between the baseband signals X _{1 to} X _m . When it is determined that there is a correlation for at least one combination, the correlation characteristic detection unit 222 notifies the output level adjustment control unit 24 that there is a correlation between the baseband signals X _{1 to} X _m . Further, the correlation characteristic detection unit 222 outputs the presence or absence of correlation between the baseband signals X _{1 to} X _m to the display control unit 26.

Next, the configuration of the fading signal generator _23Y 1 _{~23Y n,} illustrating a fading signal generator 23Y ₁ as an example. Fading signal generator 23Y ₁ is composed of a processor core section 231X ₁ ~231X _m, an adder 234, an output level adjustment section 235, and an output level measurement unit 236. Here, also for the fading signal generating unit _23Y 2 _{~23Y n,} it has the same configuration as the fading signal generating unit 23Y _1.

The arithmetic core units 231X _{1 to} 231X _m are provided in association with the input baseband signals X _{1 to} X _m . The baseband signals X _{1 to} X _m input to the fading signal generation unit 23Y ₁ are input to the corresponding computation core units. In other words, the baseband signal _{X 1} is input to the arithmetic core portion 231X _1, the baseband signal _{X m} are input to the arithmetic core portion 231X _m.

The detailed configuration of the arithmetic core units 231X _{1 to} 231X _m will be specifically described with reference to FIG. 3 taking the arithmetic core unit 231X ₁ as an example. Figure 3 is a block diagram showing a configuration of a processor core section 231X _1. Note that the arithmetic core units 231X _{2 to} 231X _m also have the same configuration as the arithmetic core unit 231X ₁ .

The arithmetic core unit 231X ₁ includes a plurality of multipath arithmetic core units 232X _{11 to} 232X _1k and an adder 233X ₁ .

The multipath calculation core unit is provided for each path constituting a multipath for simulating fading. FIG. 3 shows a configuration assuming multipaths of paths 1 to k, where the multipath computation core unit 232X ₁₁ corresponds to path 1 and the multipath computation core unit 232X _1k corresponds to path k. . Hereinafter, the configuration of the multi-pass operation core unit _232X 11 _{~232X 1k,} illustrating a multipath processor core section 232X ₁₁ as an example.

Baseband signal _{X 1} from the baseband signal generation unit 11 is output to the arithmetic core portion 231X ₁ is input to the multipath processor core section _232X 11 _{~232X 1k} respectively. That is, the multipath processor core section 232X _11, the base band signal _{X 1} is inputted. Further, the multipath computation core unit 232X ₁₁ receives information indicating the fading conditions (for example, conditions such as delay, attenuation, noise, etc.) corresponding to the path 1 from the setting control unit 25. Further, the multipath computation core unit 232X ₁₁ receives a gain G _O1 having a level set corresponding to the fading signal Y ₁ .

Fading calculation unit 21 according to this embodiment, when the fading signal _{Y 1} as an example, multipath arithmetic core portion so that the level of the fading signal _{Y 1} is _G O1 _{P IN 232X} 11 _{~232X 1k} and the output level adjustment section 235 is operated. Note that _PIN represents the input level _PIN of the baseband signals X _{1 to} X _m described above. The operations of the multipath arithmetic core units 232X _{11 to} 232X _1k and the output level adjustment unit 235 related to this control will be described later.

Multipath operation core unit 232X _11, to the baseband signals X1 input is subjected to a fading process on the basis of the fading conditions corresponding to the path 1 to generate a digital fading signal X _{11 '.} As an example of the fading process include delay processing or attenuation processing against the baseband signals X _1. Further, in accordance with the fading conditions, in order to simulate the scattering of the signal, it may be added to the noise in the baseband signal X _1. The multipath arithmetic core unit 232X ₁₁ outputs the generated fading signal X ₁₁ ′ to the adder 233X ₁ . Similarly, multi-pass operation core section _232X 12 _{~232X 1k} generates a fading signal _{X 12 '~X 1k',} and outputs the generated fading signal _{X 12 '~X 1k'} to the adder 233X _1.

The adder 233X ₁ receives the fading signals X ₁₁ ′ to X _1k ′ from the multipath arithmetic core units 232X _{11 to} 232X _1k . The adder 233X ₁ adds the fading signals X ₁₁ ′ to X _1k ′ to generate a fading signal X ₁ ′. The adder 233X ₁ outputs the generated fading signal X ₁ ′ to the adder 234 (see FIG. 2).

As described above, fading signal _{X 1} generated by the operation core unit 231X ₁ ~231X _m '~X _m' is output to the adder 234. The adder 234 adds the fading signals X ₁ ′ to X _m ′ to generate a fading signal Z ₁ . The adder 234 outputs the generated fading signal Z ₁ to the output level adjustment unit 235. In addition, the calculation core units 231X _{1 to} 231X _m and the adder 234 correspond to the “calculation core unit group”.

Output level adjustment section 235 receives the gain _{G C} from the output level adjustment control unit 24. Gain _{G C} is the output level adjustment control unit 24, is calculated for each fading signal _(Y 1 _{~Y n).} The output level adjustment control unit 24 will be described later. In still later, the gain G _C corresponding to the fading signal Y ₁ may be referred to as "gain G _C1". Similarly, if the gain G _C corresponding to the fading signal Y _n may be referred to as "gain G _Cn". In addition, when there is no need to clearly indicate the correspondence with the fading signals (Y _{1 to} Y _n ) for the sake of explanation, it is simply described as “gain G _C ”.

Further, the output level adjustment unit 235 receives the fading signal Z ₁ from the adder 234. The output level adjustment unit 235 adjusts (that is, attenuates) the level of the fading signal Z ₁ based on the gain G _C1 . The fading signal Z ₁ whose level is adjusted based on the gain G _C1 corresponds to the fading signal Y ₁ .

Further, the output level adjustment unit 235 receives a new gain _GC1 from the output level adjustment control unit 24. In this case, the output level adjustment section 235, the gain G _C1 that has been used for level adjustment of the fading signal Z _1, is updated to a new gain G _C1. Then, the output level adjustment section 235 adjusts the level of the fading signal Z ₁ based on the new gain G _C.

Output level adjustment section 235 outputs the fading signal _{Y 1} to the output level measuring unit 236 and the transmitting unit 12 (see Fig. 1).

The output level measurement unit 236 receives the fading signal Y ₁ from the output level adjustment unit 235 and measures the level of the fading signal Y ₁ as the output level P _OUT . Note that the measurement period of the output level P _OUT is the same as the measurement period T of the input level _PIN .

The output level P _OUT is also expressed as a function of accumulating Y ₁ (t) Y ₁ ^* (t) for a predetermined measurement period T. Here, Y ₁ (t) indicates the level of the fading signal Y ₁ at time t. Y ₁ ^* (t) represents a conjugate complex number of Y ₁ (t).

The output level measurement unit 236 outputs the measured output level P _OUT to the output level adjustment control unit 24. Further, the output level measurement unit 236 outputs the output level P _OUT to the display control unit 26. The output level P _OUT is measured and output by the output level measuring units 236 of the fading signal generation units 23Y _{1 to} 23Y _n individually. That is, the output level P _OUT is output to the output level adjustment control unit 24 and the display control unit 26 for each fading signal (Y _{1 to} Y _n ). Hereinafter, the output level P _OUT corresponding to the fading signal Y ₁ may be referred to as “output level P _OUT1 ”. Similarly, the output level P _OUT corresponding to the fading signal Y _n may be described as “output level P _OUTn ”. Further, when it is not necessary to clearly indicate the correspondence with the fading signals Y _{1 to} Y _n for the sake of explanation, they are simply described as “output level P _OUT ”.

When the fading simulator 20 is activated, the output level adjustment control unit 24 first specifies the method for adjusting the level of the fading signal as either “fixed gain adjustment” or “automatic gain adjustment”. Thereafter, the output level adjustment control unit 24 adjusts the levels of the fading signals Y _{1 to} Y _n by adjusting the gains G _{C1 to} G _Cn based on the specified level adjustment method. Hereinafter, the operation of the output level adjustment control unit 24 will be described by dividing it into “specification of level adjustment method” and “level adjustment of fading signal”.

(Identification of level adjustment method)
First, the operation of the output level adjustment control unit 24 related to “specification of level adjustment method” will be described with reference to FIG. FIG. 4 is a flowchart of processing relating to specification of the level adjustment method.

(Step S11)
The output level adjustment control unit 24 receives fading processing conditions from the setting control unit 25. The fading process conditions include level adjustment method, presence / absence of correlation between propagation paths, presence / absence of multipath, and gains G _{O1 to} G _On as parameters designated by the operator. The presence / absence of correlation between the propagation paths is determined from the fading process conditions set by the setting control unit 25.

(Step S12)
First, the output level adjustment control unit 24 confirms the adjustment method of the level designated by the operator. When the designated level adjustment method is not “automatic gain adjustment” (step S12, N), the output level adjustment control unit 24 sets “fixed gain adjustment” as the level adjustment method (step S19). ), The process related to specifying the level adjustment method is terminated.

(Step S13)
When the adjustment method for the designated level is “automatic gain adjustment” (step S12, Y), the output level adjustment control unit 24 checks whether or not there is a correlation between the propagation paths. When there is no correlation between the propagation paths (step S13, N), the output level adjustment control unit 24 sets “fixed gain adjustment” as the level adjustment method (step S19), and specifies the level adjustment method. The process related to is terminated.

(Step S14)
When there is a correlation between the propagation paths (step S13, Y), the output level adjustment control unit 24 confirms the presence / absence of multipath. When the multipath is set (step S14, Y), that is, when there are a plurality of paths for each propagation path, the output level adjustment control unit 24 sets “automatic gain adjustment” as the level adjustment method. After setting (step S18), the process related to specifying the level adjustment method is terminated.

(Step S15)
If the multi-path is not set (step S14, N), the output level adjustment control unit 24 checks the correlation characteristics between the baseband signal X ₁ to X _n. Therefore, first, the output level adjustment control unit 24 outputs a predetermined gain to the output level adjustment units 235 of the fading signal generation units 23Y _{1 to} 23Y _n as gains G _{C1 to} G _Cn . The predetermined gain may be set within a range in which the correlation characteristic detection unit 222 can detect the correlation characteristics of the baseband signals X _{1 to} X _n , and is determined in advance by experiments or the like.

When the gain _G C1 _{~G Cn} is set by the output level adjustment control unit 24, the fading simulator 20 starts receiving the baseband signal _X 1 to X _n from the baseband signal generation unit 11. Accordingly, the baseband signals X _{1 to} X _m output from the baseband signal generation unit 11 are input to the input level measurement unit 221, the correlation characteristic detection unit 222, and the fading signal generation units 23Y _{1 to} 23Y _n. The

(Step S16)
When the reception of the baseband signals X _{1 to} X _n is started, the output level adjustment control unit 24 is notified of the presence or absence of correlation between the baseband signals X _{1 to} X _m from the correlation characteristic detection unit 222.

(Step S17)
When there is a correlation between the baseband signals X _{1 to} X _m (step S17, Y), the output level adjustment control unit 24 sets “automatic gain adjustment” as the level adjustment method (step S18). When there is no correlation between the baseband signals X _{1 to} X _m (N in step S17), the output level adjustment control unit 24 sets “fixed gain adjustment” as the level adjustment method (step S18). When the setting of the level adjustment method is completed, the output level adjustment control unit 24 ends the process related to the specification of the level adjustment method.

(Fading signal level adjustment)
Next, the operation of the output level adjustment control unit 24 relating to “fading signal level adjustment” will be described with reference to FIG. FIG. 5 is a flowchart of processing relating to level adjustment of a fading signal.

(Step S21)
First, the output level adjustment control unit 24 outputs the initial values of the gains G _{C1 to} G _{Cn to} the output level adjustment units 235 of the fading signal generation units 23Y _{1 to} 23Y _n . The initial values of the gains G _{C1 to} G _Cn may be calculated based on fading conditions, using the set gain of “fixed gain adjustment”, in addition to using the predetermined gain described above.

(Step S22)
When the initial value of the gain _G C1 _{~G Cn} is set, the output level adjustment control unit 24 starts the generation of the fading signal _Y 1 to Y _n in the fading signal generator _23Y 1 _{~23Y n.}

(Step S23)
Next, the output level adjustment control unit 24 confirms whether or not the specified level adjustment method is “automatic gain adjustment”. When it is not “automatic gain adjustment” (step S23, N), the output level adjustment control unit 24 ends the process related to the level adjustment of the fading signal. Accordingly, the levels of the fading signals Z _{1 to} Z _n are adjusted by the output level adjusting unit 235 based on the initial values of the gains G _{C1 to} G _Cn and are output as the fading signals Y _{1 to} Y _n (that is, “fixed”). The level is adjusted based on “Gain adjustment”). When gains different from the initial values are set as the gains G _{C1 to} G _Cn when operating based on the “fixed gain adjustment”, the output level adjustment control unit 24 sets the gain G before finishing the processing. You may be able to re set the _C1 ~G _Cn.

(Step S24)
When “automatic gain adjustment” is set (step S23, Y), the output level adjustment control unit 24 receives the input level _PIN from the input level measurement unit 221.

(Step S25)
Further, the output level adjustment control unit 24 receives the output level P _OUT (that is, P _{OUT1 to} P _OUTn ) from each of the output level measuring units 236 of the fading signal generation units 23Y _{1 to} 23Y _n .

(Step S26)
Output level adjustment control unit 24, an input level _{P IN,} and an output level _{P OUT1,} based on the gain _{G O1,} calculates the level ratio _{K 1} of the fading signal _{Y 1} for the base band signal _{X 1.} Level ratio K ₁ is given by the following equation.
K ₁ = P _OUT1 / (G _O1 P _IN )

The same applies to the fading signals Y _{2 to} Y _n . That is, the output level adjustment control unit 24 calculates an input level _{P IN,} an output level _P OUT2 _{to P OUTn,} the gain _G O2 _{~G On} the level ratio _K 2 ~K _n based on. Hereinafter, the case of the fading signal Y ₁ as an example.

(Steps S27 and S28)
Output level adjustment control unit 24, the calculated level ratio K ₁ determines whether 1. Here, G _O1 P _IN indicates the output level of the fading signal Y ₁ desired by the operator. On the other hand, P _OUT1 indicates the actual output level of the fading signal Y ₁ . Therefore, when K ₁ ≠ 1 (step S27, N), the output level adjustment control unit 24 adjusts G _C1 so that K ₁ approaches 1 (step S28).

Specifically, when K ₁ is less than ₁ , the output level adjustment control unit 24 increases G _C1 so that P _OUT1 increases because P _OUT1 is smaller than G _{O1 PIN} . Further, when K ₁ is larger than ₁ , the output level adjustment control unit 24 decreases G _C1 so that P _OUT1 decreases because P _OUT1 is larger than G _O1 P _IN . In this manner, the output level adjustment control unit 24 drives the output level P _OUT1 so that K ₁ = 1. When K ₁ = 1 is satisfied (step S27, Y), the output level adjustment control unit 24 ends the process related to the level adjustment of the fading signal. The time for trumps the output level P _OUT1 is fading signal Y ₁ is set to a time that does not oscillate. This time is calculated in advance by experiments or the like and set in the output level adjustment control unit 24.

The same applies to the fading signals Y _{2 to} Y _n . That is, the output level adjustment control unit 24, the output level _P OUT2 _{to P OUTn} desired level of fading signal _Y 2 to Y _n on the basis of the level ratio _K 2 ~K _{n (i.e., G O2 P IN ~G On P} IN )

Reference is now made to FIG. The transmission unit 12 receives the fading signals Y _{1 to} Y _n from the fading calculation unit 21. The transmission unit 12 converts the fading signals Y _{1 to} Y _n into analog signals. The transmission unit 12 converts the frequency of the analog signal based on a predetermined communication method. The transmitter 12 transmits an analog signal (that is, a carrier wave) subjected to frequency conversion to the terminal 2 under test.

The display control unit 26 causes the display unit 28 to display “fading conditions” set in the fading calculation unit 21 and parameters relating to adjustment of the fading signal. Parameters relating to the adjustment of the fading signal indicate “input level P _IN ”, “output levels P _{OUT1 to} P _OUTn ”, and “presence / absence of correlation between baseband signals X _{1 to} X _m ”. Here, “input level P _IN ” and “output levels P _{OUT1 to} P _OUTn ” are relative values and cannot be specified in absolute units. Therefore, the unit “dB” may be displayed using the level ratio K described above. Or you may display by the unit "dB" by dBFS (Decibel. Full scale: dB Full Scale).

The display control unit 26 receives the “fading condition” from the setting control unit 25. In addition, the display control unit 26 receives “input level P _IN ” from the input level measurement unit 221. Further, the display control unit 26 receives “output levels P _{OUT1 to} P _OUTn ” from the output level measurement units 236 of the fading signal generation units 23Y _{1 to} 23Y _n . Further, the display control unit 26 receives a notification regarding “the presence / absence of correlation between the baseband signals X _{1 to} X _m ” from the correlation characteristic detection unit 222.

Note that the output level adjustment control unit 24 may calculate the level ratio K _{1 based} on K ₁ = P _OUT1 / P _IN . In this case, the output level adjustment control unit 24 determines whether or not K ₁ = G _O1 . If K ₁ ≠ G _O1 , the output level adjustment control unit 24 adjusts G _C1 so that K ₁ approaches G _O1 .

Further, the output level measurement unit 236 had to determine the level of the fading signal _Y 1 to Y _n as the output level _{P OUT,} may measure the level of fading signal _Z 1 to Z _n as the output level _{P OUT} . In this case, the level ratio K ₁ is calculated by the following formula.
K ₁ = (G _C1 P _OUT1 ) / (G _O1 P _IN )

Similarly for the level ratio _K 2 ~K _n, an input level _{P IN,} an output level _P OUT2 _{to P OUTn,} can be calculated based on the gain _G O2 _{~G On.}

Further, in the case where the levels of the baseband signals X _{1 to} X _m are different, the fading calculation unit 21 may be provided by the number of combinations of the levels of the base band signals X _{1 to} X _m .

Further, the output level adjustment control unit 24 may display this on the display unit 28 via the display control unit 26 when K ₁ = 1 is not satisfied within a predetermined time. As a result, the operator can detect when the output levels P _{OUT2 to} P _OUTn do not converge to a predetermined value due to oscillation of a negative feedback circuit including the output level adjusting unit 235 and the output level measuring unit 236. Can be detected.

Above, fading simulator 20 according to this embodiment, when there is a correlation between the baseband signal _X 1 to X _m, in the level _{P OUT} level _{P IN} fading signal _Y 1 to Y _m of the baseband signal calculating a level ratio _K 1 ~K _n based. Fading simulator 20, the level ratio _K 1 ~K _n updates the gain _{G C} such that 1, to adjust the level _{P OUT} of the fading signal. Thereby, the fading simulator 20 gives the level P _OUT of the fading signals Y _{1 to} Y _m to the level G _O1 P _{IN to} G desired by the operator when there is a correlation between the baseband signals X _{1 to} X _m. It can be adjusted to be _{On PIN} . Alternatively, when there is a correlation between the propagation paths, that is, when the gain cannot be uniquely specified by the fading condition, the level P _OUT of the fading signals Y _{1 to} Y _m can be similarly adjusted.

1 the mobile communication terminal test system 10 a base station simulator 11 baseband signal generation unit 12 transmission unit 20 Fading Simulator 21 fading calculation unit 221 input level measurement unit 222 correlation characteristic detector 231X ₁ ~231X _m operation core unit 232X ₁₁ ～232X _1k multipath arithmetic core unit 233X ₁ adder 234 adder 235 output level adjustment unit 236 output level measurement unit 23Y _{1 to} 23Y _n fading signal generation unit 24 output level adjustment control unit 25 setting control unit 26 display control unit 27 operation unit 28 Display 2 Terminal under test

Claims (9)

An arithmetic core unit (231X _{1 to} 231X _m ) that receives a plurality of (m) baseband signals for testing the mobile communication terminal input at the first level _PIN and performs fading processing on the baseband signals. A plurality of arithmetic core units that combine the outputs of the plurality of arithmetic core units and output as digital fading signals for each propagation path of mobile communication;
Output level adjustment unit for changing the level of the fading signal based on a predetermined gain G _C and (235),
A fading simulator comprising:
An output level measuring unit that measures the level of the fading signal whose level has been changed as the second level P _OUT when the correlation characteristic exists between the baseband signals or when there is a correlation characteristic between the propagation paths. (236),
When there is the correlation characteristic between the baseband signals or when there is a correlation characteristic between the propagation paths, a level ratio K between the first level P _IN and the second level P _OUT is calculated, as the level ratio K becomes a predetermined value, the output level adjustment control unit configured to update the gain G _C (24),
A fading simulator characterized by comprising:   The fading simulator according to claim 1, further comprising a correlation characteristic detection unit (222) for detecting presence or absence of correlation characteristics between the plurality of baseband signals. An input level measuring unit (221) for measuring the level of the baseband signal and obtaining the first level _PIN ;
The fading simulator according to claim 1, wherein the output level adjustment control unit calculates the level ratio K based on a measurement result (P _IN ) of the input level measurement unit.   A plurality (n) of sets of the arithmetic core unit group, the level adjustment unit, and the output level measurement unit are provided for the plurality (m) of baseband signals, and a plurality of different fading signals are output. The fading simulator according to claim 1, wherein the fading simulator is characterized in that: A display (28);
A display control unit (26) for displaying the level ratio K on the display unit;
The fading simulator according to any one of claims 1 to 4, further comprising:   6. The fading simulator according to claim 1, wherein if the level ratio K does not reach the predetermined value during a predetermined period, the fact is notified. A baseband signal generator (11) that generates a plurality of (m) digital baseband signals for testing having a first level _PIN as an output level;
A fading simulator (20) for receiving the plurality of baseband signals and outputting a plurality (n) of fading signals in accordance with propagation paths constituting MIMO;
A transmission unit (12) that converts each fading signal output from the fading simulator into an analog signal, converts the frequency according to a predetermined communication method, and outputs the converted signal to a mobile communication terminal to be tested;
In a mobile communication terminal test system comprising:
The fading simulator is
A plurality of arithmetic core units (231X _{1 to} 231X _m ) that receive the plurality of baseband signals and perform fading processing on the baseband signals, and combine the outputs of the plurality of arithmetic core units for each propagation path; An arithmetic core group for outputting as a digital fading signal;
Output level adjustment unit for changing the level of the fading signal based on a predetermined gain G _C and (235),
An output level measuring unit that measures the level of the fading signal whose level has been changed as the second level P _OUT when the correlation characteristic exists between the baseband signals or when there is a correlation characteristic between the propagation paths. (236),
When the correlation characteristic is present between the baseband signals or when there is a correlation characteristic between the propagation paths, the ratio between the first level _PIN and the second level _POUT is calculated as a level ratio K. and, as the level ratio K becomes a predetermined value, the output level adjustment control unit configured to update the gain G _C (24),
A mobile communication terminal test system comprising:   The fading simulator includes a plurality (n) of sets of the arithmetic core unit group, the level adjustment unit, and the output level measurement unit for the plurality (m) of baseband signals, and a plurality of different fading signals. The mobile communication terminal test system according to claim 6, wherein: Fading processing using a fading simulator (20) that receives a plurality of baseband signals for testing a mobile communication terminal input at the first level _PIN and outputs a fading signal for each propagation path of mobile communication A method,
A correlation characteristic detecting step for detecting one or both of presence / absence of correlation characteristics between the plurality of baseband signals and presence / absence of correlation characteristics between the propagation paths;
Fading processing step of performing fading processing on the plurality of baseband signals, combining the outputs and outputting as a fading signal;
A level adjustment step of changing a level of the fading signal based on a predetermined gain G _C,
Second measurement that measures the level of the fading signal whose level has been changed as the second level P _OUT when the correlation characteristic exists between the baseband signals or when there is a correlation characteristic between the propagation paths Steps,
When the correlation characteristic exists between the baseband signals before or when the correlation characteristic exists between the propagation paths, a level ratio K between the first level P _IN and the second level P _OUT is calculated. , so that the level ratio K becomes a predetermined value, the gain adjustment step of updating the gain G _C,
A fading processing method characterized by comprising:

Images