Measuring device and measuring method

Abstract

To make it possible to measure a delay profile between a transmitter and a receiver of a system to be measured without transmitting a specific signal from a measuring device.SOLUTION: A measuring device includes: a signal converter 1 that is connected to a first receiving antenna 4 arranged near a transmitter 2 of a wireless communication system 200 and a second receiving antenna 3 arranged at a receiver position of a delay profile measurement point of the wireless communication system 200, and converts analog signals from the first receiving antenna 4 and the second receiving antenna into digital signals; and a signal processing device 5 that receives input of the digital signals from the signal converter 1, and calculates a delay profile PDP(t) at time t on the basis of a transfer function Hi(ω) of an input signal (CH1) to the first receiving antenna 4, a transfer function Ho(ω) of an input signal (CH2) to the second receiving antenna 3, and a ratio of the transfer function Ho(ω) to the transfer function Hi(ω), Hoi(ω)=Ho(ω) / Hi(ω).SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The technology described herein relates to a measurement apparatus and a measurement method. [Background technology]

[0002] Measurement of the power delay profile (PDP) for wireless communication systems is used in channel design of wireless systems, including multi-channel or multiple-input multiple-output (MIMO) designs (see, for example, Non-Patent Document 1).

[0003] FIG. 1 is a block diagram showing a schematic configuration example of a wireless communication system 600 in the related art.

[0004] The wireless communication system 600 includes a PDP measurement device 6, a transmitter (Tx) 7, and a receiver (Rx) 8. The PDP measurement device 6 may be called a sounder, and inputs a Tx signal to Tx 7. Tx 7 transmits a signal to Rx via a multi-channel transmission path based on the input Tx signal. Rx 8 inputs the Rx signal received from Tx 7 to the PDP measurement device 6. Then, the PDP measurement device 6 calculates a delay profile.

[0005] The delay profile PDP(t) may be calculated based on the following formula when So(t) is the received signal (Rx signal) and Sr(t) is a special reference signal (for example, in the case of a modulated wave of a PN code such as the longest code sequence, the Tx signal is also a modulated wave of the same PN code).

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[0006] Furthermore, when a Vector Network Analyser (VNA) is applied as the PDP measurement device 6, the Tx signal and the Rx signal may be frequency-swept continuous wave (CW) signals. In this case, the delay profile PDP(t) may be calculated based on the following equation, where Hs(ω) is the transfer function of the wireless communication system 600. Note that IFFT stands for inverse Fourier transform.

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[0007] [Patent Document 1] JP 2012-178877 A [Patent Document 2] JP 2008-228200 A [Non-patent literature]

[0008] [Non-Patent Document 1] Theodore S, George R. MacCartney, Jr., Mathew K. Samimi, Shu Sun, “Wideband Millimeter-Wave Propagation Measurements and Channel Models for Future Wireless Communication System Design,” IEEE TRANSACTIONS ON COMMUNICATIONS, VOL. 63, NO. 9, September 2015. Summary of the Invention [Problem to be solved by the invention]

[0009] However, the conventional PDP measurement device 6 has a problem in that a specific transmission signal output from the PDP measurement device 6 must be output from Tx 7 of the wireless communication system 600.

[0010] In one aspect, the technology described in this specification aims to make it possible to measure the delay profile between the transmitter and receiver of a system under test without sending a specific signal from a measurement device. [Means for solving the problem]

[0011] In one aspect, a measurement device is a measurement device that measures a delay profile of an arriving signal of a wireless communication system, which is a system under test, and includes: a signal converter that is connected to a first receiving antenna arranged near a transmitter of the wireless communication system and a second receiving antenna arranged at a receiver position of a delay profile measurement point of the wireless communication system, and converts analog signals from the first receiving antenna and the second receiving antenna into digital signals; and a signal processing device that receives input of the digital signal from the signal converter and calculates the delay profile PDP(t) at time t based on a transfer function Hi(ω) of an input signal (CH1) to the first receiving antenna, a transfer function Ho(ω) of an input signal (CH2) to the second receiving antenna, and Hoi(ω)=Ho(ω) / Hi(ω), which is the ratio of the transfer function Ho(ω) to the transfer function Hi(ω). Effect of the Invention

[0012] As one aspect, it is possible to measure the delay profile between the transmitter and receiver of the system under test without sending out a specific signal from the measurement device. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a block diagram illustrating a configuration example of a conventional wireless communication system. [Diagram 2] FIG. 1 is a block diagram illustrating a schematic configuration example of a measurement device according to an embodiment. [Diagram 3] 11 is a graph illustrating side lobe suppression and time resolution by a signal processing device in an embodiment. [Figure 4]13(a) is a graph illustrating side lobe suppression and time resolution when the Multiple Signal Classification (MUSIC) method is applied to a single piece of data in the modified example, and (b) is a graph illustrating side lobe suppression and time resolution when the MUSIC method is applied to multiple pieces of data in the modified example. [Diagram 5] 2 is a block diagram illustrating an example of a hardware configuration of a signal converter, an antenna, and a signal processing device according to an embodiment. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, an embodiment will be described with reference to the drawings. However, the embodiment described below is merely an example, and is not intended to exclude various modifications and application of techniques not explicitly stated in the embodiment. In other words, the present embodiment can be modified in various ways without departing from the spirit of the present invention.

[0015] In addition, each figure does not necessarily include only the components shown in the figure, but may include other components. In the following drawings, parts with the same reference numerals indicate the same or similar parts unless otherwise specified.

[0016] [Example of embodiment] 2 is a block diagram illustrating a schematic configuration example of a measurement device 100 according to an embodiment. Here, a Local 5G system will be described as a system to be measured (in other words, a wireless communication system 200).

[0017] The measurement device 100 includes a signal converter 1, a transmitter (L5G RU; Local 5th Generation Radio Unit) 2, a receiver (Rx; receiving antenna for receiving) 3, a receiving antenna for transmitting 4, and a signal processing device 5. In this embodiment, a PC is used as the signal processing device 5. In this embodiment, an oscilloscope is used as the signal converter 1.

[0018] Tx2 transmits an arbitrary signal to Rx via a multi-channel transmission line. Rx3 inputs the signal (CH2) received from Tx2 to a signal converter (oscilloscope) 1.

[0019] Tx2 also transmits an arbitrary signal to the transmitting receiving antenna 4. The transmitting receiving antenna 4 inputs the signal (CH1) received from Tx2 to a signal converter (oscilloscope) 1. The signal input to the signal converter (oscilloscope) 1 is sent to a signal processing device (PC) 5 as digital data.

[0020] The signal converter (oscilloscope) 1 is an example of the measurement device 100, and may be a spectrum monitor using a direct RF undersampling type ADC (analog to digital converter). The signal processor (PC) 5 calculates a delay profile using a digitized signal (CH1) input from the transmitting receiving antenna 4 and a signal (CH2) input from Rx3.

[0021] The delay profile PDP(t) is CH1 is the input signal (reference signal) of CH1, and S CH2 When is the input signal (received signal) of CH2, it may be calculated based on the following formula:

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[0022] FIG. 3 is a graph illustrating side lobe suppression and time resolution by the signal processing device 5 in the embodiment.

[0023] Reference symbol A1 in Fig. 3 illustrates an example of the PDP characteristics calculated by the signal processing device 5. Reference symbol A11 represents a direct wave, and the region indicated by reference symbol A12 is a multipath wave.

[0024] The side lobes indicated by symbols A13 and A14 are generated by an error due to zero padding. Zero padding indicates the calculation of Ho(ω) / Hi(ω) by converting the waveform indicated by symbol A22 into the waveform indicated by symbol A23 based on the transfer function Hi(ω) indicated by symbol A21. Specifically, zero padding is performed when the absolute value of Hi(ω) is extremely small compared to the values ​​of other frequencies (for example, 10% with respect to the peak). -4 As shown in Figure 3, when the Ho(ω) / Hi(ω) value is extremely large, other important information is buried, so this process sets the Ho(ω) / Hi(ω) value to 0.

[0025] In addition, in reference symbol A15 in FIG. 3, if the system transmission signal band of the transmitter 2 is B, then the time resolution ΔT=1 / B, and for example, in the case of a Local 5G system, B≈100 Hz, ΔT≈10 ns.

[0026] According to the measuring device 100 in the embodiment, it is possible to measure the delay profile between the transmitter and receiver of the wireless communication system 200, which is the system under test, without sending a specific signal from the wireless communication system 200, which is the system under test (without changing the transmitter circuit or the signal processing method).

[0027] [Modifications of the embodiment] According to the example of the above-mentioned embodiment, the PDP can be obtained, but the side lobes due to the above-mentioned zero padding process become relatively large, and the time resolution is determined by the system transmission signal bandwidth B. Therefore, in the modified example, the MUSIC method is applied to measure the PDP.

[0028] The following description will be given taking the MUSIC method as an example, but is not limited thereto. The advantages of the following embodiment can be obtained by using a method that uses an eigenvector of a signal correlation matrix, such as the ESPRIT method. The delay profile PDPmusic(t) by the MUSIC method is S CH1 is the input signal (reference signal) of CH1, and S CH2is the input signal (received signal) of CH2, p is the maximum number of dimensions of the signal, M is the total number of dimensions, V is the eigenvector of the signal correlation matrix obtained from the correlation matrix of Hoi(ω), e(t) is a complex sine wave vector, and V H When V is the conjugate transpose of V, it may be calculated based on the following formula:

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[0029] In the MUSIC method, the desired PDP characteristics are obtained from the eigenvectors of the correlation matrix, so that the time resolution is basically not limited by the system band B, and therefore higher time resolution characteristics can be obtained.

[0030] In the MUSIC method, processing is often performed on multiple pieces of data called snapshots, so here, for example, 1 ms of data is divided into 10 parts in the time direction, and the correlation matrix is ​​calculated for each of these as snapshots.

[0031] FIG. 4(a) is a graph illustrating side lobe suppression and time resolution when the MUSIC method is applied to a single piece of data (in this example, 10 snapshots) in the modified example, and FIG. 4(b) is a graph illustrating side lobe suppression and time resolution when the MUSIC method is applied to multiple pieces of data (in this example, 46 pieces of data) (460 (10 × 46) snapshots) under the same conditions in the modified example.

[0032] In FIG. 4(a), when the MUSIC method is applied to the same data, the degree of side lobe suppression is approximately 15 dB at most, which is equivalent to that of the embodiment, as shown by symbols B1 and B2. However, as shown by symbol B3, the time resolution is approximately 10 times that of the original embodiment, and a multipath signal B3 that could not be observed in the original embodiment can be observed.

[0033] Furthermore, multiple data may be measured to increase the number of snapshots, so that the side lobes caused by the zero padding process described above can be regarded as noise that does not appear at a fixed position, and the side lobes can be suppressed if the number of data can be increased.

[0034] In FIG. 4(b), when the MUSIC method is applied to 46 pieces of data, as shown by symbols C1 and C2, the degree of side lobe suppression is improved to a maximum of about 20 dB, which is higher than the original embodiment, and the time resolution is about 10 times higher than that of the embodiment.

[0035] In other words, by using the modified embodiment, the output time resolution can be set smaller than the time resolution determined by the bandwidth B of the wireless communication system 200, which is the system under test, and the side lobes due to zero padding can also be made smaller.

[0036] [Hardware configuration example] FIG. 5 is a block diagram showing a schematic example of a hardware configuration of a signal converter (oscilloscope) 1, antennas 3 and 4, and a signal processing device 5 in the embodiment.

[0037] Antenna 4 (receiving antenna for transmitting) is placed near transmitter 2 of the system under test, as shown in Fig. 2. Antenna 3 (receiving antenna for receiving) is placed at a point in the system under test where the delay profile is to be measured, and corresponds to receiver 3 of the system under test. Signals from each of antennas 3 and 4 are input to signal converter 1.

[0038] 5 shows a case where an oscilloscope is used as the signal converter 1. The signal converter 1 includes a CPU 11, a main memory 12, a display control unit 13, a storage device 14, an input IF 15, an external recording medium processing unit 16, a communication IF 17, and an ADC circuit 18. Similarly, the signal processing device 5 may include the CPU 11, the main memory 12, the display control unit 13, the storage device 14, the input IF 15, the external recording medium processing unit 16, and the communication IF 17.

[0039] The main memory 12 is an example of a storage unit, and is illustratively a Read Only Memory (ROM) and a Random Access Memory (RAM). Programs such as a Basic Input / Output System (BIOS) may be written in the ROM of the main memory 12. The software programs in the main memory 12 may be appropriately read and executed by the CPU 11. The RAM of the main memory 12 may be used as a temporary storage memory or a working memory.

[0040] The display control unit 13 is connected to a display device 131 and controls the display device 131. The display device 131 is a liquid crystal display, an organic light-emitting diode (OLED) display, a cathode ray tube (CRT), an electronic paper display, or the like, and displays various information for an operator, etc. The display device 131 may be combined with an input device, for example, a touch panel. The display device 131 displays various information for a user of the signal converter (oscilloscope) 1.

[0041] The storage device 14 is a storage device with high IO performance, and may be, for example, a dynamic random access memory (DRAM), a solid state drive (SSD), a storage class memory (SCM), or a hard disk drive (HDD).

[0042] The input IF 15 may be connected to input devices such as a mouse 151 and a keyboard 152, and may control the input devices such as the mouse 151 and the keyboard 152. The mouse 151 and the keyboard 152 are examples of input devices, and an operator performs various input operations via these input devices.

[0043] The external recording medium processing unit 16 is configured so that a recording medium 160 can be attached thereto. The external recording medium processing unit 16 is configured so that, when the recording medium 160 is attached, the information recorded on the recording medium 160 can be read. In this example, the recording medium 160 is portable. For example, the recording medium 160 is a flexible disk, an optical disk, a magnetic disk, a magneto-optical disk, a semiconductor memory, or the like. Specifically, the signal data of CH1 and CH2 converted into digital values ​​by the ADC circuit 18 described below may be sent to the signal processing device (PC) 5 via the recording medium 160.

[0044] The communication IF 17 is an interface for enabling communication with an external device. As described above, the signal data of CH1 and CH2 may be sent to the signal processing device (PC) 5 via the recording medium 160, or data may be sent to the signal processing device (PC) 5 via the communication IF 17.

[0045] The ADC circuit 18 has the function of converting signals input from a terminal (CH1) that receives a signal from a receiving antenna 4 for receiving a transmitted signal that is placed near the transmitter 2 of the system under test described above, and a terminal (CH2) that receives a signal from a receiving antenna for a receiving point of the delay profile measurement point of the system under test described above (where the receiver 3 of the system under test is installed), into digital signals and transmitting them to a common bus.

[0046] The CPU 11 is an example of a processor, and is a processing device that performs various controls and calculations. The CPU 11 executes an Operating System (OS) and programs loaded into the main memory 12 to realize various functions. The CPU 11 may be a multiprocessor including multiple CPUs, a multicore processor having multiple CPU cores, or a configuration having multiple multicore processors. In this embodiment, the signal data of CH1 and CH2 is sent to the signal processing device (PC) 5 via the recording medium 160 or the communication IF 17, but it is also possible to perform the processing of the present invention using the CPU 11 and memory 12 in the oscilloscope without using the external signal processing device (PC) 5 to obtain a PDP.

[0047] The signal processing device 5 uses the above-mentioned CH1 signal and CH2 signal sent from the signal converter (oscilloscope) 1 to obtain the PDP through the signal processing of the present invention.

[0048] The measurement device and the measurement method of the present embodiment enable the measurement of the delay profile between the transmitter and the receiver without sending a specific signal from the measurement device of the system under test. This eliminates the need to change the circuit or signal processing of the transmitter of the system under test. In addition, it enables the PDP measurement of the signal of the system under test itself, enabling more accurate PDP measurement. This is particularly effective when the transmission signal of the system under test cannot be changed due to laws and regulations. The measured PDP characteristics are effective in identifying the communication capacity in multipath communication.

[0049] Furthermore, the measurement apparatus and method of this embodiment can achieve improved time resolution and suppression of side lobes, close to conventional PDP measurements, by applying the MUSIC method.

[0050] The disclosed technology is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the embodiments. The configurations and processes of the embodiments can be selected as necessary, or can be combined as appropriate.

[0051] In the above-described embodiment, the wireless communication system 200, which is the system under test, performs Local 5G communication, but is not limited thereto. The wireless communication system 200, which is the system under test, may perform 4G communication or 3G communication. [Explanation of symbols]

[0052] 1: Signal converter 2, 7: Tx 3, 8: Rx 4: Transmitting and receiving antenna 5: Signal processing device 6: PDP measuring device 11: CPU 12: Main memory 13: Display control section 14:Storage device 15: Input IF 16: External recording medium processing unit 17: Communication Interface 18:ADC circuit 100, 600: Measuring equipment 131:Display device 151: Mouse 152: Keyboard 160: Recording media 200: Wireless communication system

Claims

1. A measurement device for measuring a delay profile of an arriving signal of a wireless communication system that is a system under test, comprising: a signal converter connected to a first receiving antenna disposed near a transmitter of the wireless communication system and a second receiving antenna disposed at a receiver position of a delay profile measurement point of the wireless communication system, the signal converter converting analog signals from the first receiving antenna and the second receiving antenna into digital signals; a signal processing device that receives an input of the digital signal from the signal converter, and calculates the delay profile PDP(t) at time t based on a transfer function Hi(ω) of an input signal (CH1) to the first receiving antenna, a transfer function Ho(ω) of an input signal (CH2) to the second receiving antenna, and a ratio of the transfer function Ho(ω) to the transfer function Hi(ω), Ho(ω)=Ho(ω) / Hi(ω); A measuring device comprising:

2. The signal processing device includes:

2. The measurement device according to claim 1, further comprising: a zero padding process for setting the value of Hoi(.omega.) to 0 when the absolute value of Hi(.omega.) is extremely small compared to values ​​of other frequencies.

3. The signal processing device includes: When FFT represents Fourier transform, IFFT represents inverse Fourier transform, Hi(ω)=FFT(CH1), and Ho(ω)=FFT(CH2), the delay profile at time t is calculated using the formula PDP(t)=IFFT(Hoi(ω)).

3. The measuring device according to claim 1 or 2.

4. Calculate the delay profile PDP(t) from the Hoi(ω) using a method using eigenvectors of a signal correlation matrix.

3. The measuring device according to claim 1 or 2.

5. The signal processing device includes: Using the Multiple Signal Classification (MUSIC) method, [0010] (p is the maximum number of dimensions of the signal, M is the total number of dimensions, V is the eigenvector of the signal correlation matrix obtained from the correlation matrix of Hoi(ω), e(t) is a complex sine wave vector, and V Ｈ represents a conjugate transpose matrix of V), the delay profile PDP(t) is calculated based on the following equation:

5. The measuring device according to claim 4, characterized in that

6. The signal processing device includes: Setting an output time resolution smaller than a time resolution determined by a bandwidth of the system under test; 5. The measuring device according to claim 4, characterized in that

7. The signal processing device includes: Calculating the delay profile PDP(t) based on at least one of snapshots obtained by dividing data in the time direction and snapshots obtained from a plurality of data items under the same conditions.

5. The measuring device according to claim 4, characterized in that

8. A measuring device for measuring a delay profile of an arriving signal of a wireless communication system that is a system under test, the measuring device including a signal converter and a signal processing device, the signal converter is connected to a first receiving antenna arranged near a transmitter of the wireless communication system and a second receiving antenna arranged at a receiver position of a delay profile measurement point of the wireless communication system, and converts analog signals from the first receiving antenna and the second receiving antenna into digital signals; The signal processing device calculates the delay profile PDP(t) at time t based on a transfer function Hi(ω) of an input signal (CH1) to the first receiving antenna, a transfer function Ho(ω) of an input signal (CH2) to the second receiving antenna, and a ratio of the transfer function Ho(ω) to the transfer function Hi(ω), Ho(ω)=Ho(ω) / Hi(ω); A measuring method comprising:

9. The signal processing device includes: When the absolute value of Hi(ω) is extremely small compared to the values ​​of other frequencies, a zero padding process is performed to set the value of Hoi(ω) to 0. The method according to claim 8 .

10. The signal processing device includes: When FFT represents Fourier transform, IFFT represents inverse Fourier transform, Hi(ω)=FFT(CH1), and Ho(ω)=FFT(CH2), the delay profile at time t is calculated using the formula PDP(t)=IFFT(Ho(ω)). The method for measuring according to claim 8 or 9.

11. Calculate the delay profile PDP(t) from the Hoi(ω) using a method using eigenvectors of a signal correlation matrix. The method for measuring according to claim 8 or 9.

12. The signal processing device includes: Using the Multiple Signal Classification (MUSIC) method, [0025] (p is the maximum number of dimensions of the signal, M is the total number of dimensions, V is the eigenvector of the signal correlation matrix obtained from the correlation matrix of Hoi(ω), e(t) is a complex sine wave vector, and V Ｈ represents a conjugate transpose matrix of V), the delay profile PDP(t) is calculated based on the following equation: The method according to claim 11 ,

13. The signal processing device includes: Setting an output time resolution smaller than a time resolution determined by a bandwidth of the system under test; The measurement method according to claim 11 .

14. The signal processing device includes: Calculating the delay profile PDP(t) based on at least one of snapshots obtained by dividing data in the time direction and snapshots obtained from a plurality of data items under the same conditions. The measurement method according to claim 11 .

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