Wireless terminal testing device and method for displaying carrier frequency fluctuations

Abstract

This invention provides a wireless terminal testing device and a carrier frequency fluctuation display method that easily identify when a call is disconnected due to fluctuations in the carrier frequency. [Solution] The wireless terminal test device 1 includes a satellite orbit calculation unit 12 that calculates the satellite orbit based on the satellite's position information and moving speed at the start of measurement; a Doppler shift calculation unit 13 that calculates the amount of Doppler shift based on the satellite orbit and the position information of the UE100, and displays the difference between the carrier frequency of the downlink signal and the carrier frequency at the start of measurement, and the difference between the carrier frequency of the uplink signal and the carrier frequency at the start of measurement, as theoretical values ​​on the display unit 19; a Doppler shift removal unit 16 that removes the Doppler shift of the uplink signal; and a frequency error detection unit 18 that calculates the difference between the carrier frequency after removing the Doppler shift and the carrier frequency at the start of measurement, and displays it as a measured value on the display unit.

Description

Technical Field

[0001] The present invention relates to a wireless terminal test apparatus that simulates a base station of a wireless communication system to test a wireless terminal.

Background Art

[0002] When developing a wireless terminal that uses wireless communication for network connection such as an IoT (Internet of Things) terminal, it is necessary to test whether the developed wireless terminal can communicate normally. For this reason, a test apparatus that operates as a pseudo base station that simulates the functions of an actual base station is connected to the wireless terminal to be tested, communication is performed between the test apparatus and the wireless terminal, and a test is performed to confirm the content of this communication.

[0003] NB-IoT (NarrowBand Internet of Things) has been standardized as a communication means for IoT terminals. In addition, NTN (Non-Terrestrial Network), a non-terrestrial network using satellites that can be used in NB-IoT, has also been defined.

[0004] Patent Document 1 describes that in NTN, uplink synchronization is executed by appropriately setting TA (Timing Advance) between an airborne base station and a terminal.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] When simulating communication between NB-IoT wireless terminals via NTN, a configuration is created where a satellite is inserted between the base station and the wireless terminal. Because the satellite is moving, fluctuations in the carrier frequency occur due to the Doppler effect (doppler shift).

[0007] As the duration of the call connection increases, the range of carrier frequency fluctuations widens, resulting in carrier frequency fluctuations that significantly exceed the 15kHz or 3.75kHz subcarrier interval.

[0008] Attempting to correct the frequency during reception processing is only possible up to half the subcarrier interval; therefore, the carrier frequency must be corrected before reception processing. However, if the satellite orbit calculations do not match between the radio terminal and the base station, the correction cannot be performed correctly, resulting in the call being disconnected. Identifying the source of the anomaly takes time.

[0009] Therefore, the present invention aims to provide a wireless terminal testing device that can easily identify when a call has been disconnected due to fluctuations in the carrier frequency. [Means for solving the problem]

[0010] The wireless terminal testing apparatus of the present invention is a wireless terminal testing apparatus (1) that simulates communication between a wireless terminal (100) and a satellite to perform testing of the wireless terminal, and displays the theoretical value of the carrier frequency of the uplink signal and the change in the measured value over time on a display unit (19).

[0011] This configuration displays the theoretical and measured carrier frequencies of the uplink signal as they change over time. Therefore, it is easy to verify the difference between the theoretical and measured carrier frequencies, and to easily identify if a call was disconnected due to carrier frequency fluctuations.

[0012] Furthermore, the wireless terminal testing apparatus of the present invention displays not only the theoretical value and the change in measured value of the carrier frequency of the uplink signal over time, but also the change in the theoretical value of the carrier frequency of the downlink signal over time on the display unit.

[0013] This configuration displays not only the theoretical and measured changes in the uplink signal's carrier frequency over time, but also the changes in the theoretical carrier frequency of the downlink signal over time. Therefore, it is possible to check the changes in the theoretical carrier frequency of the downlink signal over time as well, making it easy to identify when a call is disconnected due to fluctuations in the carrier frequency.

[0014] Furthermore, the wireless terminal testing device of the present invention displays the change in carrier frequency over time based on the difference from the carrier frequency at the start of measurement.

[0015] This configuration displays the change in carrier frequency over time based on the difference from the carrier frequency at the start of measurement. Therefore, changes in carrier frequency can be easily identified, and it becomes easy to determine if a call was disconnected due to fluctuations in carrier frequency.

[0016] Furthermore, the carrier frequency fluctuation display method of the present invention is a carrier frequency fluctuation display method for a wireless terminal test device (1) that simulates communication between a wireless terminal (100) and a satellite to test the wireless terminal, and comprises the steps of: calculating the satellite orbit based on the satellite's position information and speed at the start of measurement; calculating the amount of Doppler shift between the satellite and the wireless terminal based on the satellite orbit and the position information of the wireless terminal; displaying the difference between the carrier frequency of the downlink signal and the carrier frequency at the start of measurement, and the difference between the carrier frequency of the uplink signal and the carrier frequency at the start of measurement, as theoretical values, based on the calculated amount of Doppler shift; and displaying the difference between the carrier frequency of the uplink signal after the Doppler shift has been removed and the carrier frequency at the start of measurement, as a measured value, based on the calculated amount of Doppler shift.

[0017] This configuration displays the theoretical and measured carrier frequencies of the uplink signal, as well as the change in the theoretical carrier frequency of the downlink signal over time, as the difference from the carrier frequency at the start of measurement. This makes it easy to check changes in the carrier frequency and to easily identify when a call is disconnected due to fluctuations in the carrier frequency. [Effects of the Invention]

[0018] The present invention provides a wireless terminal testing device that can easily identify when a call has been disconnected due to fluctuations in the carrier frequency. [Brief explanation of the drawing]

[0019] [Figure 1] Figure 1 is a block diagram of a wireless terminal test device according to one embodiment of the present invention. [Figure 2] Figure 2 shows an example of displaying the change in carrier frequencies of downlink and uplink signals over time in a wireless terminal test device according to one embodiment of the present invention. [Figure 3]FIG. 3 is a flowchart for explaining the procedure of carrier frequency display processing of the wireless terminal test apparatus according to an embodiment of the present invention.

Embodiments for Carrying Out the Invention

[0020] Hereinafter, referring to the drawings, the wireless terminal test apparatus according to the embodiment of the present invention will be described in detail.

[0021] In FIG. 1, a wireless terminal test apparatus 1 according to an embodiment of the present invention is connected to a UE (User Equipment) 100 as a wireless terminal via a coaxial cable or the like, and performs a measurement test by transmitting and receiving RF (radio frequency) signals with the UE 100 by simulating a base station.

[0022] The wireless terminal test apparatus 1 includes a scenario processing unit 11, a satellite orbit calculation unit 12, a Doppler shift calculation unit 13, a transmission processing unit 14, a Doppler shift addition unit 15, a Doppler shift removal unit 16, a reception processing unit 17, a frequency error detection unit 18, and a display unit 19.

[0023] The scenario processing unit 11 creates a scenario for simulating a base station based on settings for simulating a base station input from a user, and simulates the base station based on the scenario. When performing a test of communication via NTN, the position information of the satellite and the UE 100 and the moving speed of the satellite are set in the scenario.

[0024] The satellite orbit calculation unit 12 calculates a satellite orbit based on the position information and moving speed of the satellite at the start of measurement.

[0025] The Doppler shift calculation unit 13 calculates the amount of Doppler shift between the satellite and UE100 based on the satellite orbit and the position information of UE100. Based on the calculated amount of Doppler shift, the Doppler shift calculation unit 13 displays the difference between the carrier frequency of the downlink signal and the carrier frequency at the start of measurement, and the difference between the carrier frequency of the uplink signal and the carrier frequency at the start of measurement, as theoretical values ​​on the display unit 19.

[0026] The transmission processing unit 14 generates a downlink signal that includes broadcast information necessary for the UE100 to establish a call connection.

[0027] The Doppler shift addition unit 15 calculates the amount of Doppler shift due to satellite movement based on the amount of Doppler shift calculated by the Doppler shift calculation unit 13, and adds the Doppler shift to the downlink signal generated by the transmission processing unit 14 before transmitting it.

[0028] The Doppler shift removal unit 16 removes the Doppler shift added to the uplink signal based on the amount of Doppler shift calculated by the Doppler shift calculation unit 13 and outputs it to the receiving processing unit 17.

[0029] The receiving processing unit 17 performs receiving processing such as timing synchronization processing and demodulation processing of the received uplink signal, and outputs the processed signal.

[0030] The frequency error detection unit 18 calculates the difference between the carrier frequency after the Doppler shift has been removed by the Doppler shift removal unit 16 and the original carrier frequency at the start of measurement, and displays it as a measured value on the display unit 19.

[0031] The display unit 19 consists of an image display device such as a liquid crystal display and displays images generated by the Doppler shift calculation unit 13, the frequency error detection unit 18, etc.

[0032] Here, the wireless terminal test device 1 is composed of a computer device (not shown) equipped with a communication module for communicating with the UE100. This computer device includes a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), a storage device such as a hard disk drive, input / output ports, and a touch panel (all not shown).

[0033] The ROM and hard disk drive of this computer device store programs that enable the computer device to function as a wireless terminal test device 1. In other words, the CPU executes the programs stored in the ROM using the RAM as a working area, thereby enabling the computer device to function as a wireless terminal test device 1.

[0034] Thus, in this embodiment, the scenario processing unit 11, satellite orbit calculation unit 12, Doppler shift calculation unit 13, and frequency error detection unit 18 are configured by a CPU, while the transmission processing unit 14, Doppler shift addition unit 15, Doppler shift removal unit 16, and reception processing unit 17 are configured by a communication module.

[0035] In the wireless terminal test apparatus 1 with this configuration, the Doppler shift calculation unit 13 and the frequency error detection unit 18 display the change in the carrier frequency of the downlink signal and uplink signal over time on the display unit 19.

[0036] The Doppler shift calculation unit 13 and the frequency error detection unit 18 display, for example, the change in the theoretical value of the carrier frequency of the downlink signal over time, and the change in the measured value and theoretical value of the carrier frequency of the uplink signal over time, on the display unit 19 as a graph, as shown in Figure 2.

[0037] In Figure 2, the theoretical values ​​of the carrier frequencies of the downlink signal and the uplink signal increase similarly over time, but the measured value of the uplink signal's carrier frequency increases faster.

[0038] In this way, by displaying the measured and theoretical changes in carrier frequency, it is easy to identify when a call is disconnected due to fluctuations in carrier frequency.

[0039] The carrier frequency display process by the wireless terminal test device 1 configured as described above according to this embodiment will be explained with reference to Figure 3. The carrier frequency display process described below is started when the user selects to start communication with UE100.

[0040] In step S1, the satellite orbit calculation unit 12 calculates the satellite orbit based on the satellite's position information and velocity at the start of the measurement. After executing the process in step S1, the Doppler shift calculation unit 13 executes the process in step S2.

[0041] In step S2, the Doppler shift calculation unit 13 calculates the amount of Doppler shift based on the satellite orbit and the position information of UE100. After performing the process in step S2, the Doppler shift addition unit 15 performs the process in step S3, and the Doppler shift removal unit 16 performs the process in step S5.

[0042] In step S3, the Doppler shift addition unit 15 calculates the amount of Doppler shift due to satellite movement and adds it to the downlink signal generated by the transmission processing unit 14. After executing the process in step S3, the Doppler shift addition unit 15 executes the process in step S4.

[0043] In step S4, the Doppler shift addition unit 15 transmits a downlink signal with a Doppler shift added. After executing the process in step S4, the Doppler shift calculation unit 13 executes the process in step S8.

[0044] In step S5, the Doppler shift removal unit 16 removes the Doppler shift added to the uplink signal and outputs it to the receiving processing unit 17. After executing the process in step S5, the receiving processing unit 17 executes the process in step S6.

[0045] In step S6, the receiving processing unit 17 receives the uplink signal and performs receiving processing. After executing the processing in step S6, the frequency error detection unit 18 executes the processing in step S7.

[0046] In step S7, the frequency error detection unit 18 calculates the difference between the carrier frequency after the Doppler shift has been removed and the original carrier frequency at the start of the measurement. After performing the process in step S7, the frequency error detection unit 18 performs the process in step S8.

[0047] In step S8, the Doppler shift calculation unit 13 displays the change in the carrier frequency of the downlink signal over time and the change in the theoretical value of the carrier frequency of the uplink signal over time on the display unit 19, and the frequency error detection unit 18 displays the change in the measured value of the carrier frequency of the uplink signal over time on the display unit 19. After executing the process in step S8, the Doppler shift calculation unit 13 and the frequency error detection unit 18 terminate the carrier frequency display process.

[0048] As described above, in the above embodiment, the wireless terminal test device 1 displays the theoretical value of the carrier frequency of the uplink signal and the change in the measured value over time on the display unit 19.

[0049] This makes it easy to check the theoretical and measured changes in the uplink signal's carrier frequency over time, and to easily identify when a call was disconnected due to fluctuations in the carrier frequency.

[0050] Furthermore, the wireless terminal test device 1 displays on the display unit 19 not only the theoretical value and the change in measured value of the uplink signal's carrier frequency over time, but also the change in the theoretical value of the downlink signal's carrier frequency over time.

[0051] This allows us to also check the change in the theoretical value of the downlink signal's carrier frequency over time, making it easy to identify that the call was disconnected due to fluctuations in the carrier frequency.

[0052] Furthermore, the wireless terminal test device 1 displays the change in carrier frequency over time based on the difference from the carrier frequency at the start of measurement.

[0053] This makes it easy to check for changes in carrier frequency and to easily identify that a call was disconnected due to fluctuations in carrier frequency.

[0054] While embodiments of the present invention have been disclosed, it will be apparent to those skilled in the art that modifications can be made without departing from the scope of the invention. All such modifications and equivalents are intended to be included in the following claims. [Explanation of symbols]

[0055] 1. Wireless terminal testing equipment 11 Scenario Processing Unit 12 Satellite orbit calculation section 13. Doppler shift calculation unit 14 Transmission Processing Unit 15 Doppler shift addition part 16 Doppler shift removal section 17 Receiving Processing Unit 18 Frequency error detection unit 19 Display section 100 UE (Wireless Terminal)

Claims

1. A wireless terminal test device (1) that simulates communication between a wireless terminal (100) and a satellite to perform a test of the wireless terminal, A wireless terminal test device that displays the theoretical value and the change in the measured value of the carrier frequency of the uplink signal over time on a display unit (19).

2. The wireless terminal testing apparatus according to claim 1, which displays, in addition to the change over time between the theoretical value and the measured value of the carrier frequency of the uplink signal, the change over time between the theoretical value and the measured value of the carrier frequency of the downlink signal.

3. A wireless terminal testing apparatus according to claim 1 or claim 2, which displays the change in carrier frequency over time based on the difference from the carrier frequency at the start of measurement.

4. A method for displaying carrier frequency fluctuations of a wireless terminal test device (1) that performs tests on a wireless terminal (100) by simulating communication with the wireless terminal via satellite, A step of calculating the satellite orbit based on the satellite's position information and speed at the start of the measurement, A step of calculating the amount of Doppler shift between the satellite and the wireless terminal based on the satellite orbit and the position information of the wireless terminal, Based on the calculated Doppler shift amount, the steps include displaying the difference between the carrier frequency of the downlink signal and the carrier frequency at the start of measurement, and the difference between the carrier frequency of the uplink signal and the carrier frequency at the start of measurement, as theoretical values, A carrier frequency fluctuation display method comprising the steps of: displaying the difference between the carrier frequency of the uplink signal after the Doppler shift has been removed and the carrier frequency at the start of the measurement as a measured value, based on the calculated Doppler shift amount.

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