JP6964948B2 - Measuring device and measuring method - Google Patents

Description

The present invention relates to a measuring device and a measuring method, and more particularly to a measuring device and a measuring method for measuring a test object that operates based on a wireless LAN communication standard.

With the development of information and communication technology, various wireless communication technologies have been developed. Among these, as communication standards related to wireless LAN technology, for example, IEEE802.11n and IEEE802.11ac are known. 802.11n supports high processing rates (HT) with data processing speeds of up to 540 Mbps or higher, minimizes transmission errors, and multiplexes on both the transmit and receive sides to optimize data rates. MIMO (Multiple Inputs and Multiple Outputs) technology that uses antennas has been introduced. IEEE802.11ac supports Very High Throughput (VHT), which is higher than the data processing speeds supported by IEEE802.11n.

In recent years, as the next version of IEEE802.11ac, IEEE802.11ax, which is a high efficiency (HE) wireless LAN standard, has been proposed. IEEE802.11ax realizes an average throughput of about 4 times per user as compared with IEEE802.11ac in a crowded communication environment where a large number of users communicate.

In a wireless LAN system, when a destination wireless communication device receives a frame transmitted from a source wireless communication device, the destination wireless communication device receives an acknowledgment (ACK) frame when the entire frame can be received without error. Is returned to the wireless communication device of the source. The wireless communication device of the source retransmits the frame when the ACK frame cannot be received. In this case, it is common to lower the data rate of the frame in order to increase the delivery probability of the frame. be.

Further, if the wireless communication device of the transmission source cannot receive the ACK frame even when the data rate of the frame is set to the minimum, the communication standard may be changed to retransmit the frame. For example, as shown in FIG. 5, in the wireless communication device 30 of the transmission source, a frame conforming to the IEEE802.11ax standard having the lowest data rate (hereinafter, also referred to as “IEEE802.11ax frame”) is the transmission destination wireless communication. If it is not received by the device 40, the communication standard is changed to an IEEE802.11 standard other than IEEE802.11ax (for example, IEEE802.11a) and the frame is retransmitted.

By the way, as a measuring device that measures the wireless communication device of the transmission source as described above (Device Under Test: DUT), there is a measuring device that measures the characteristics of the DUT in a state of being connected to the DUT via a network (for example,). See Patent Document 1).

Japanese Patent No. 4675743

However, when an IEEE802.11ax frame is transmitted from the DUT, if the measuring device does not have a demodulation / decoding function corresponding to the IEEE802.11ax standard, the measuring device detects the IEEE802.11ax frame from the DUT. Can not do it. For this reason, there is a problem that a reception error occurs, frames are frequently resent from the DUT, and it becomes impossible to maintain the transmission of the IEEE802.11ax frame from the DUT.

The present invention has been made to solve such a conventional problem, and even when a reception error occurs in a frame conforming to the IEEE802.11ax standard, the IEEE802.11ax from the test object is used. It is an object of the present invention to provide a measuring device and a measuring method capable of maintaining the transmission of a frame conforming to a standard and performing a measurement on an object to be tested.

In order to solve the above problems, the measuring device according to the present invention transmits a frame conforming to the IEEE802.11ax standard to a predetermined destination, and then confirms and responds to the frame indicating that the frame has been received by the destination. Is a measuring device that measures a subject to be tested, which retransmits a frame conforming to a communication standard different from the IEEE802.11ax standard when the frame is not received, and the frame transmitted from the subject to be tested is used. An OFDM that extracts from the complex baseband signal a receiver that converts to a digital complex baseband signal, an OFDM symbol that includes a legacy signal field (L-SIG), and an OFDM symbol that follows the OFDM symbol that contains L-SIG. The symbol extraction unit, the demodulation / decoding unit that demodulates and decodes the two OFDM symbols extracted by the OFDM symbol extraction unit, and the bit strings of the two OFDM symbols demodulated and decoded by the demodulation / decoding unit match. When the comparison determination unit determines that the bit strings of the two OFDM symbols demodulated and decoded by the demodulation / decoding unit match the comparison determination unit that determines whether or not the confirmation response frame is subject to the test. A confirmation response transmission unit to be transmitted to the It is a configuration.

With this configuration, the measuring device according to the present invention can detect a frame conforming to the IEEE802.11ax standard with a low-cost configuration. Further, the measuring device according to the present invention maintains the transmission of the frame conforming to the IEEE802.11ax standard from the test subject even when a reception error occurs in the frame conforming to the IEEE802.11ax standard. Measurements for the test object can be performed with a network connection. That is, when the measuring device according to the present invention receives a frame compliant with the IEEE802.11ax standard at the receiving unit, the measuring device can perform measurement on the frame compliant with the IEEE802.11ax standard.

Further, in the measuring device according to the present invention, the receiving unit may receive the response frame transmitted by the test object in response to the ping command as the frame.

Here, "Ping" is an ICMP Echo Request (the response is an ICMP Echo Reply).

With this configuration, the measuring device according to the present invention can measure the response frame when the subject to be tested receives the response frame transmitted in response to the ping command at the receiving unit.

Further, in the measuring device according to the present invention, the measuring unit may measure the transmission characteristics of the test object.

With this configuration, the measuring device according to the present invention can measure the transmission characteristics of the test object by the measuring unit.

Further, in the measurement method according to the present invention, after transmitting a frame conforming to the IEEE802.11ax standard to a predetermined destination, a confirmation response frame indicating that the frame has been received by the destination is not received. In addition, it is a measurement method in which a measurement is performed on a test object that retransmits a frame conforming to a communication standard different from the IEEE802.11ax standard, and the frame transmitted from the test object is a digital complex baseband signal. The OFDM symbol extraction step of extracting the OFDM symbol including the legacy signal field (L-SIG) and the OFDM symbol following the OFDM symbol including the L-SIG from the complex baseband signal, and the above-mentioned It is determined whether or not the demodulation / decoding step of demodulating and decoding the two OFDM symbols extracted by the OFDM symbol extraction step and the bit strings of the two OFDM symbols demodulated and decoded by the demodulation / decoding step match. When the comparison determination step determines that the bit strings of the two OFDM symbols demodulated and decoded by the demodulation / decoding step match, the confirmation response frame is transmitted to the test object. The configuration includes a step and a measurement step of measuring the frame determined by the comparison determination step that the bit strings of the two OFDM symbols demodulated and decoded by the demodulation / decoding step match.

With this configuration, the measuring method according to the present invention can detect a frame conforming to the IEEE802.11ax standard with a low-cost configuration. Further, the measurement method according to the present invention maintains the transmission of the frame conforming to the IEEE802.11ax standard from the test subject even when a reception error occurs in the frame conforming to the IEEE802.11ax standard. Measurements for the test object can be performed with a network connection. That is, in the measurement method according to the present invention, when a frame compliant with the IEEE802.11ax standard is received by the receiving unit, measurement can be performed on the frame compliant with the IEEE802.11ax standard.

The present invention maintains the transmission of the frame conforming to the IEEE802.11ax standard from the test subject and measures the subject to be tested even when a reception error occurs in the frame conforming to the IEEE802.11ax standard. It provides a measuring device and a measuring method capable of capable.

It is a block diagram which shows the structure of the measuring apparatus which concerns on embodiment of this invention. (A) is a diagram showing the frame format of IEEE802.11ax, and (b) is a diagram showing the frame format of IEEE802.11a. It is a flowchart which shows the process of the measurement method using the measuring apparatus which concerns on embodiment of this invention. It is a sequence diagram for demonstrating the process in the flowchart shown in FIG. It is a sequence diagram for demonstrating frame transmission / reception between conventional wireless communication devices.

Hereinafter, embodiments of the measuring apparatus and measuring method according to the present invention will be described with reference to the drawings.

As shown in FIG. 1, the measuring device 10 according to the present embodiment wirelessly communicates with the DUT1 and measures the DUT1. In the present embodiment, the measuring device 10 operates as a wireless LAN master unit (AP: Access Point), and the DUT1 operates as a wireless LAN slave unit (STA: STAtion), but the present invention is not limited thereto. The measuring device 10 may operate as a wireless LAN slave unit, and the DUT 1 may operate as a wireless LAN master unit. The measuring device 10 shall communicate with DUT1 based on the communication standard based on IEEE802.11.

The DUT1 transmits a frame conforming to the IEEE802.11ax standard generated by using a predetermined modulation method and code rate to the measuring device 10 as a transmission destination, and then the frame is received by the measuring device 10. When the confirmation response frame (ACK frame) indicating the above is not received, the frame conforming to the communication standard different from the IEEE802.11ax standard is retransmitted so that the delivery probability to the measuring device 10 is increased. Here, the communication standard different from the IEEE802.11ax standard is, for example, a communication standard compliant with any of IEEE802.11a / b / g / n / ac.

The frame transmitted / received between the DUT 1 and the measuring device 10 includes a header portion having a low data rate and a data portion having a high data rate. For example, FIG. 2A shows the frame format of IEEE802.11ax, and FIG. 2B shows the frame format of IEEE802.11a.

“L-STF”, “L-LTF”, and “L-SIG” shown in FIG. 2 are so-called legacy preambles, and are communication of any of IEEE802.11a / b / g / n / ac / ax. Decoding is possible if the wireless communication device conforms to the standard. Further, the RL-SIG in FIG. 2A is a field peculiar to the IEEE802.11ax standard, and is a complete copy of the L-SIG.

As shown in FIG. 1, the measuring device 10 of the present embodiment includes a transmission data generation unit 11, a frame generation unit 12, a transmission unit 13, a reception unit 14, an OFDM symbol extraction unit 15, and a demodulation / decoding unit. 16, a comparison determination unit 17, a measurement unit 18, a display unit 19, an operation unit 20, and a control unit 21 are provided.

The transmission data generation unit 11 generates transmission data set by the user and outputs it to the frame generation unit 12.

The frame generation unit 12 generates (configures) a frame including the data output from the transmission data generation unit 11 and outputs the frame to the transmission unit 13.

The transmitting unit 13 and the receiving unit 14 are adapted to establish a wireless communication connection (network connection) with the DUT1 based on a communication standard compliant with IEEE802.11. Further, the transmitting unit 13 and the receiving unit 14 transmit and receive various data related to the measurement with the DUT1 after the network connection is established.

For example, the receiving unit 14 includes a receiving antenna, a down converter, an ADC (analog digital converter), and the like. For example, the receiving unit 14 down-converts the frame transmitted from the DUT 1 into an analog baseband signal and then performs orthogonal detection, and the orthogonally detected analog baseband signal is digitally complex-based by analog digital conversion (A / D). The reception process for converting to a band signal is performed. Further, the receiving unit 14 outputs the digital complex baseband signal obtained by receiving and processing the frame transmitted from the DUT1 to the OFDM symbol extraction unit 15 and the measuring unit 18.

The OFDM symbol extraction unit 15 extracts an OFDM symbol including a legacy signal field (L-SIG) and an OFDM symbol following the OFDM symbol including the L-SIG from the complex baseband signal received and processed by the reception unit 14. It is designed to do.

The demodulation / decoding unit 16 demodulates and decodes the two OFDM symbols extracted by the OFDM symbol extraction unit 15, respectively. For example, the demodulation / decoding unit 16 performs OFDM demodulation by FFT processing and demodulation of any one of BPSK, QPSK, 16QAM, 64QAM, 256QAM, and the like. Further, the demodulation / decoding unit 16 decodes the demodulated OFDM symbol corresponding to any of IEEE802.11a / b / g / n / ac. That is, it is assumed that the measuring device 10 of the present embodiment does not have a function of performing demodulation and decoding corresponding to IEEE802.11ax.

When the frame transmitted from DUT1 is an IEEE802.11ax frame as shown in FIG. 2A, the number of bits of the OFDM symbol bit string including the demodulated and decoded L-SIG is 24 bits. Similarly, the number of bits in the bit string of the OFDM symbol including the demodulated and decoded RL-SIG is 24 bits.

The comparison determination unit 17 determines whether or not the bit strings of the two OFDM symbols demodulated and decoded by the demodulation / decoding unit 16 match, and when the bit strings of these two OFDM symbols match, the IEEE802.11ax frame Is now determined to have been detected.

When the frame transmitted from DUT1 is an IEEE802.11ax frame as shown in FIG. 2A, the comparison determination unit 17 includes an OFDM symbol including L-SIG and an OFDM symbol including RL-SIG. Therefore, it is determined that the bit strings of these two OFDM symbols match. On the other hand, as shown in FIG. 2B, when the frame transmitted from DUT1 is not an IEEE802.11ax frame, this frame does not include the RL-SIG, so that the frame is the bit string of the OFDM symbol including the L-SIG. , The probability that the bit string of the OFDM symbol following the OFDM symbol including L-SIG completely matches is 0.5 to the 24th power, which is extremely low. In this way, the comparison determination unit 17 can detect the IEEE802.11ax frame with high accuracy.

The transmission unit 13 includes a coding processing circuit, a modulation circuit, a DAC (digital-to-analog converter), an upconverter, a transmission antenna, and the like, and constitutes a frame transmission unit 13a and an acknowledgment transmission unit 13b.

The frame transmission unit 13a transmits the frame generated by the frame generation unit 12 to the DUT1 via the transmission antenna after performing processing such as digital modulation and up-conversion.

When establishing a network connection with the DUT1, the confirmation response transmitting unit 13b outputs an ACK frame to the DUT1 every time the receiving unit 14 receives a frame transmitted from the DUT1.

Further, when the confirmation response transmission unit 13b measures the frame received from the DUT1 after the network connection, the comparison determination unit 17 determines that the bit strings of the two OFDM symbols demodulated and decoded by the demodulation / decoding unit 16 match. Only when this is done, the ACK frame is transmitted to DUT1.

In this way, when the acknowledgment transmission unit 13b detects the IEEE802.11ax frame by the comparison determination unit 17, the acknowledgment transmission unit 13b returns the ACK frame to the DUT1. Therefore, the acknowledgment transmission unit 13b transmits the IEEE802.11ax frame by the transmission source DUT1. Can be maintained.

The frame received by the receiving unit 14 for measurement from the DUT1 is an IEEE802.11ax frame. For example, when the frame transmitting unit 13a transmits a ping request frame to the DUT1 by a ping command, the ping request frame. It is a Ping reply frame (response frame) transmitted by DUT1 in response to. Alternatively, the frame received by the receiving unit 14 from DUT1 may be a frame containing pulse pattern data such as a pseudo-random bit sequence.

For example, the data portion of the Ping reply frame includes Ping data. The ping data includes ping command data and transmission characteristic measurement data. The data for measuring transmission characteristics includes, for example, data patterns such as "0000 ...", "0101 ...", "1010 ...", and is used by the user to measure a predetermined transmission characteristic. It is the data set by. By using these data patterns, the measuring device 10 can identify a data pattern in which an error is likely to occur in the transmission characteristic evaluation of the DUT1.

The measurement unit 18 measures the transmission characteristics of the DUT1 for the IEEE802.11ax frame determined by the comparison determination unit 17 that the bit strings of the two OFDM symbols demodulated and decoded by the demodulation / decoding unit 16 match. It has become. Specifically, the measuring unit 18 can measure, for example, transmission power, error vector amplitude (EVM), constellation, spectrum, and the like as transmission characteristics of DUT1.

Even if the reception environment of the measuring device 10 is poor and there is a reception error in the high data rate data portion of the frame received by the receiving unit 14, the measuring unit 18 compares with the analysis process. Since it is possible to take a certain amount of time, it may be possible to measure the transmission characteristics.

Here, "when the reception environment of the measuring device 10 is poor" means, for example, that the transmission power of the DUT1 is constant, but the radiant power is not constant in all directions, and the strength of the radiant power varies depending on the direction. It means such a situation. In such a situation, when the measuring device 10 is used to perform a test (OTA test, TRP measurement / TIS measurement) regarding the antenna directivity of the DUT1, the power reaching the receiving side of the measuring device 10 is not constant.

The display unit 19 is composed of a display device such as an LCD or a CRT, and according to a control signal from the control unit 21, a measurement result of the transmission characteristics of the DUT1 by the measurement unit 18, a determination result by the comparison determination unit 17, and the like. Various display contents are displayed. Further, the display unit 19 displays an operation target such as a soft key for setting various conditions, a pull-down menu, and a text box.

The operation unit 20 is for receiving an operation input by a user, and is composed of, for example, a touch panel provided on the surface of the display screen of the display unit 19. Alternatively, the operating unit 20 may be configured to include an input device such as a keyboard or mouse. Further, the operation unit 20 may be configured by an external control device that performs remote control by a remote command or the like.

The operation input to the operation unit 20 is detected by the control unit 21. For example, by operating the operation unit 20 by the user, the user can specify the type of transmission characteristic measurement to be executed by the measurement unit 18.

The control unit 21 is composed of, for example, a microcomputer or a personal computer including a CPU, ROM, RAM, HDD, etc., and controls the operation of each of the above units constituting the measuring device 10.

The transmission data generation unit 11, the frame generation unit 12, the OFDM symbol extraction unit 15, the demodulation / decoding unit 16, the comparison judgment unit 17, and the measurement unit 18 are an FPGA (Field Programmable Gate Array) or an ASIC (Application Specific Integrated Circuit). ), Or by executing a predetermined program by the control unit 21, it can be configured as software. Alternatively, the transmission data generation unit 11, the frame generation unit 12, the OFDM symbol extraction unit 15, the demodulation / decoding unit 16, the comparison judgment unit 17, and the measurement unit 18 are subjected to hardware processing by a digital circuit and software processing by a predetermined program. Can be combined as appropriate.

Hereinafter, an example of the processing of the measurement method using the measurement device 10 of the present embodiment will be described with reference to the flowchart of FIG. Here, when the frame transmitted from the DUT1 is an IEEE802.11ax frame, the process of maintaining the transmission of the IEEE802.11ax frame by the DUT1 will be described. Here, it is assumed that the frame received by the receiving unit 14 from DUT1 for measurement is the Ping reply frame.

First, the transmitting unit 13 and the receiving unit 14 perform network connection processing including communication connection establishment processing and the like with the DUT1 based on the communication standard conforming to IEEE802.11 (step S11).

Next, the frame transmission unit 13a transmits a Ping request frame to DUT1 (step S12).

Next, the receiving unit 14 converts the Ping reply frame transmitted from the DUT1 into a digital complex baseband signal (reception step S13).

Next, the OFDM symbol extraction unit 15 extracts an OFDM symbol including L-SIG and an OFDM symbol following the OFDM symbol containing L-SIG from the complex baseband signal obtained in the reception step S13 (OFDM). Symbol extraction step S14).

Next, the demodulation / decoding unit 16 demodulates and decodes the two OFDM symbols extracted in the OFDM symbol extraction step S14, respectively (demodulation / decoding step S15).

Next, the comparison determination unit 17 determines whether or not the IEEE802.11ax frame has been detected by determining whether or not the bit strings of the two OFDM symbols demodulated and decoded in the demodulation / decoding step S15 match. (Comparison determination step S16).

If it is determined in the comparison determination step S16 that the IEEE802.11ax frame is not detected, the control unit 21 ends the process. Here, when the IEEE802.11ax frame is not detected in the comparison determination step S16, for example, when the DUT1 transmits a frame conforming to the IEEE802.11 standard which is not an IEEE802.11ax frame, or when the frame transmitted from the DUT1 is transmitted. This is a case where the reception environment of the measuring device 10 is so bad that the header portion cannot be received.

On the other hand, if it is determined in the comparison determination step S16 that an IEEE802.11ax frame has been detected, the frame transmission unit 13a transmits an ACK frame as an acknowledgment frame to the DUT1 (acknowledgement transmission step S17).

Next, the measurement unit 18 measures the transmission characteristics of the DUT1 with respect to the Ping reply frame determined to conform to the IEEE802.11ax standard in the comparison determination step S16 (measurement step S18).

Next, the display unit 19 displays the measurement result measured by the measurement unit 18 on the screen (step S19).

Next, an example of the process of transmitting and receiving frames from steps S12 to S17 described above will be specifically described with reference to FIG.

The measuring device 10 transmits a Ping request frame to DUT1. When the DUT1 receives the Ping request frame, it transmits an ACK frame indicating that the Ping request frame has been received to the measuring device 10.

Subsequently, the DUT1 transmits a Ping reply frame in response to the Ping request frame to the measuring device 10.

When the measuring device 10 determines that the Ping reply frame is an IEEE802.11ax frame, it transmits an ACK frame to DUT1 and measures the transmission characteristic using the Ping reply frame as a frame to be measured.

As described above, the measuring device 10 according to the present embodiment has a demodulation / decoding function corresponding to any of IEEE802.11a / b / g / n / ac, but demodulation corresponding to IEEE802.11ax. -A device that does not have a decryption function. However, the measuring device 10 detects an IEEE802.11ax frame with a low-cost configuration by including a comparison determination unit 17 that compares the bit string of the L-SIG of the received frame with the bit string of the field following the L-SIG. be able to.

Further, the measuring device 10 according to the present embodiment transmits an ACK frame to the DUT1 when the comparison determination unit 17 detects an IEEE802.11ax frame. Therefore, the measuring device 10 according to the present embodiment maintains the transmission of the IEEE802.11ax frame from the DUT1 even when a reception error occurs in the IEEE802.11ax frame, and measures the DUT1 in the network connection state. Can be carried out.

That is, when the measuring device 10 according to the present embodiment receives the IEEE802.11ax frame, the measuring device 10 can measure the IEEE802.11ax frame.

Further, when the receiving unit 14 receives the Ping reply frame transmitted by the DUT1 in response to the ping command, the measuring device 10 according to the present embodiment can measure the Ping reply frame.

Further, the measuring device 10 according to the present embodiment can measure the transmission characteristics of the DUT 1 by the measuring unit 18.

1 DUT
10 Measuring device 11 Transmission data generation unit 12 Frame generation unit 13 Transmission unit 13a Frame transmission unit 13b Confirmation response transmission unit 14 Reception unit 15 OFDM symbol extraction unit 16 Demodulation / decoding unit 17 Comparison judgment unit 18 Measurement unit 19 Display unit 20 Operation unit 21 Control unit

Claims (4)

Communication different from the IEEE802.11ax standard when a frame conforming to the IEEE802.11ax standard is transmitted to a predetermined destination and then an acknowledgment frame indicating that the frame has been received by the destination is not received. A measuring device (10) that measures a test object (1) that retransmits a frame conforming to the standard.
A receiver (14) that converts the frame transmitted from the test object into a digital complex baseband signal, and a receiver (14).
An OFDM symbol extraction unit (15) that extracts an OFDM symbol including a legacy signal field (L-SIG) and an OFDM symbol following the OFDM symbol including the L-SIG from the complex baseband signal.
A demodulation / decoding unit (16) that demodulates and decodes the two OFDM symbols extracted by the OFDM symbol extraction unit, respectively.
A comparative determination unit (17) that determines whether or not the bit strings of the two OFDM symbols demodulated and decoded by the demodulation / decoding unit match.
When the comparison determination unit determines that the bit strings of the two OFDM symbols demodulated and decoded by the demodulation / decoding unit match, the confirmation response transmission unit (13b) transmits the confirmation response frame to the test target. ,
A measurement including a measurement unit (18) that measures the frame determined by the comparison determination unit that the bit strings of the two OFDM symbols demodulated and decoded by the demodulation / decoding unit match. Device. The measuring device according to claim 1, wherein the receiving unit receives a response frame transmitted by the test object in response to a ping command as the frame. The measuring device according to claim 1 or 2, wherein the measuring unit measures the transmission characteristics of the object to be tested. Communication different from the IEEE802.11ax standard when a frame conforming to the IEEE802.11ax standard is transmitted to a predetermined destination and then an acknowledgment frame indicating that the frame has been received by the destination is not received. It is a measurement method that measures the subject (1) to be tested, which retransmits a frame conforming to the standard.
A reception step (S13) for converting the frame transmitted from the test object into a digital complex baseband signal, and
An OFDM symbol extraction step (S14) for extracting an OFDM symbol including a legacy signal field (L-SIG) and an OFDM symbol following the OFDM symbol containing L-SIG from the complex baseband signal.
A demodulation / decoding step (S15) for demodulating and decoding the two OFDM symbols extracted by the OFDM symbol extraction step, respectively.
A comparative determination step (S16) for determining whether or not the bit strings of the two OFDM symbols demodulated and decoded by the demodulation / decoding step match, and a comparison determination step (S16).
When the comparison determination step determines that the bit strings of the two OFDM symbols demodulated and decoded by the demodulation / decoding step match, the confirmation response frame is transmitted to the test target in the confirmation response transmission step (S17). ,
A measurement including a measurement step (S18) in which a measurement is performed on the frame determined by the comparison determination step that the bit strings of the two OFDM symbols demodulated and decoded by the demodulation / decoding step match. Method.

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