Communication devices, control methods, and recording media are computer-readable.

Abstract

According to one implementation scheme, the communication equipment used in the distributed antenna system receives orthogonal frequency division multiplexing (OFDM) signals transmitted in time-division multiplexing mode. This equipment includes a receiver that converts the OFDM signal into a baseband time-domain waveform, a time-domain waveform analyzer that calculates the correlation value from the time-domain portion of the waveform, a fast Fourier transform (FFT) that performs the FFT on the time-domain waveform, and a frequency waveform analyzer that calculates the correlation from the frequency-domain portion of the waveform. The equipment also includes a transition time estimator that estimates the transition time between uplink and downlink communication, a synchronous signal power analyzer that calculates the power of the frequency-domain portion of the waveform, and a power display that displays the calculated power.

Description

Communication device, control method, and program

[0001] The present invention relates to a communication device, a control method, and a program.

[0002] A distributed antenna system (DAS) is known as a solution to improve indoor coverage in mobile communication systems. A distributed antenna system relays signals between mobile stations and base stations and consists of a master unit and multiple slave units located in different locations. The master unit distributes signals from a single base station to multiple slave units, and each slave unit outputs the same downlink signal from its respective antenna, thereby creating an area as a single cell.

[0003] In conventional distributed antenna systems, the parent device converts RF signals into digital signals, transmits them as is, and then the child devices convert them back into analog signals, so there is no need for the system to have the function to decode control signals, etc. However, 5G-compatible TDD repeaters now have the function to decode control signals in order to detect the TDD switching timing.

[0004] Japanese Patent Application Publication No. 2021-114677

[0005] In a distributed antenna system, the base station and the parent unit are connected by a coaxial cable. Therefore, if the correct RF level is not input from the base station to the parent unit, the system level diagram cannot be maintained. In conventional distributed antenna systems, the input level from the base station was measured and displayed using an RF detector, but with 5G signals, the correct level could not be determined based on the RF detector level alone.

[0006] The embodiments of the present invention have been made in consideration of the above circumstances, and provide a communication device, a control method, and a program that allow a user to recognize appropriate power.

[0007] A communication device according to one embodiment is a distributed antenna system including a master station connected to a base station and one or more slave station devices that relay signals between a terminal device that communicates with the base station and the master station. The communication device functions as the master station or the slave station and receives an OFDM signal transmitted by a time division multiplexing method, and includes a signal receiving unit that receives the OFDM signal and converts it into a baseband time domain waveform signal, a time waveform calculation unit that extracts a portion of the time domain waveform signal that is an output of the signal receiving unit and calculates a correlation value between the extracted signal and a known signal, and a time waveform calculation unit that calculates a correlation value between the extracted signal and a known signal. a frequency waveform calculation unit that extracts a portion of the time-axis waveform signal that is the output of the FFT unit and calculates the degree of similarity between the extracted signal and a known signal; a switching timing estimation unit that estimates a switching timing between uplink communication and downlink communication in the device based on the calculation result of the frequency waveform calculation unit; a synchronization signal power calculation unit that extracts a portion of the frequency-axis waveform signal that is the output of the FFT unit and calculates the power of the extracted frequency-axis waveform signal; and a power display unit that displays the calculation result of the synchronization signal power calculation unit.

[0008] FIG. 1 is a schematic diagram showing an example of the configuration of a distributed antenna system according to an embodiment. FIG. 2 is a diagram showing an example of the data configuration of a radio frame. FIG. 3 is a diagram showing an example of an SSB allocation pattern in a radio frame. FIG. 4 is a diagram showing an example of a DL / UL configuration and SSB allocation in a TDD system. FIG. 5 is a diagram showing an example of the functional configuration of a master station device according to an embodiment. FIG. 6 is a diagram showing an example of the functional configuration of a control unit according to an embodiment. FIG. 7 is a diagram showing an example of the functional configuration of a switching timing generation unit according to an embodiment. FIG. 8 is a diagram showing an example of the functional configuration of a PSS detection unit according to an embodiment. FIG. 9 is a diagram showing an example of the functional configuration of an SSS detection unit according to an embodiment. FIG. 10 is a diagram showing an example of the functional configuration of a DMRS detection unit according to an embodiment. FIG. 11 is a diagram showing an example of the functional configuration of a synchronization signal power calculation unit according to an embodiment. FIG. 12 is a diagram showing an example of a screen displayed by a power display unit according to an embodiment. FIG. 13 is a flowchart showing an example of a synchronization signal power calculation process and a power display process according to an embodiment. FIG. 14 is a diagram showing another example of the functional configuration of a synchronization signal power calculation unit according to an embodiment. FIG. 15 is a diagram showing another example of the functional configuration of a synchronization signal power calculation unit according to an embodiment. Embodiment

[0009] The communication device, the control method, and the program will be described in detail below with reference to the accompanying drawings. In the following description of each embodiment and modification, parts with the same reference numerals have substantially the same functions, and the description of overlapping parts will be omitted as appropriate.

[0010] 1 is a diagram illustrating an example of a schematic configuration of a distributed antenna system 1 according to a first embodiment. The distributed antenna system 1 includes a master station device 10 (MU), a relay device 20 (HU), a slave station device 30 (RU), and a transmission path 40 connecting these devices. More specifically, the distributed antenna system 1 includes the master station device 10 connected to a base station 50, and one or more slave station devices 30 that relay signals between the master station device 10 and a terminal device 60 that communicates with the base station 50.

[0011] A master station device 10 is connected to a plurality of slave station devices 30 within the distributed antenna system 1. As shown in Fig. 1 , the master station device 10 may be connected to a plurality of slave station devices 30 via relay devices 20, or may be connected to a plurality of slave station devices 30 directly. Furthermore, as shown in Fig. 1 , the master station device 10 may be connected to a plurality of relay devices 20 in a cascade configuration.

[0012] The master station device 10 is connected to the base station 50 via a coaxial cable, and transmits and receives radio signals to and from the base station 50. Here, the radio signals are signals in a radio communication band that are transmitted to the terminal devices 60. The master station device 10 relays radio signals received from the base station 50 to the relay device 20 or the slave station device 30. The master station device 10 also relays radio signals received from the relay device 20 or the slave station device 30 to the base station 50.

[0013] The slave station device 30 is connected by a wired cable to an antenna 70 for wireless communication with the terminal device 60, and transmits and receives wireless signals to and from the terminal device 60 via this antenna 70. The slave station device 30 relays wireless signals received from the terminal device 60 to the master station device 10 or the relay device 20. The slave station device 30 also relays wireless signals received from the master station device 10 or the relay device 20 to the terminal device 60.

[0014] The distributed antenna system 1 having such a configuration makes it possible to connect wireless terminals that cannot be directly reached by radio waves to the base station 50, thereby expanding the communication range of the mobile communication network covered by the base station 50. For example, the distributed antenna system 1 is applicable to mobile communication networks such as 5G.

[0015] In a distributed antenna system 1 including a master station device 10 connected to a base station 50 and one or more slave station devices 30 that relay signals between the master station device 10 and terminal devices 60 that communicate with the base station 50, the master station device 10 functions as either the master station device 10 or the slave station device 30 and is a communication device that receives Orthogonal Frequency Division Multiplexing (OFDM) signals transmitted by a time division multiplexing method. The master station device 10 also receives radio frames including a synchronization signal block (SS / PBCH block) in the distributed antenna system 1 that uses a TDD method in which DL communication and UL communication are switched at predetermined intervals. The SSB includes a primary synchronization signal (PSS), a secondary synchronization signal (SSS), and a physical broadcast channel (PBCH). The master station device 10 then detects and decodes the SSB from the received radio frame, thereby determining the position in the radio frame where the received SSB was located.

[0016] The master station device 10 estimates the DL / UL switching timing based on the position of the SSB in the wireless frame and the DL / UL pattern of the TDD system. This allows the master station device 10 to estimate the DL / UL switching timing even when there is no power (signal) in the first symbol of the wireless frame of a 5G wireless signal or the like.

[0017] FIG. 2 is a diagram illustrating an example of the data structure of a radio frame. FIG. 2 shows an example of a 5G radio frame. One frame is transmitted every 10 ms. Each frame consists of 10 subframes, each transmitted every 1 ms. 5G supports multiple subcarrier frequency intervals, which result in different symbol lengths. For this reason, the concept of slots is incorporated into the radio frame, where the number of symbols per subframe is divided into multiple slots. The difference in symbol length due to the difference in subcarrier frequency intervals is absorbed by the number of slots per subframe. One slot has 14 symbols, regardless of the subcarrier frequency interval. FIG. 2 shows a case where the subcarrier frequency interval is 30 kHz, with one subframe consisting of two slots and 28 symbols. As shown in FIG. 2, SSBs are placed at specific positions in the radio frame.

[0018] FIG. 3 shows an example of an SSB placement pattern in a radio frame. An SSB is composed of four symbols. The SSB also includes two synchronization signals, a PSS and an SSS, and a PBCH signal. The PBCH signal includes a Demodulation of Reference Signal (DMRS) for the PBCH signal, which is a reference signal for decoding the PBCH signal. An SSB index number is assigned to each SSB position within the radio frame. For example, in Japan, values ​​from 0 to 7 are assigned, as shown in FIG. 2. Since the location of an SSB is up to the operator, after detecting an SSB, it is necessary to identify the location of the SSB.

[0019] Figure 4 shows an example of a DL / UL configuration and SSB allocation in a TDD system. The SSB shown in Figure 4 shows a case where the subcarrier frequency spacing is 30 kHz, the SSB period is 20 ms, and the transmission period is 5 ms. The transmission period includes 10 slots, with the first 6 slots assigned to DL and the last 3 slots assigned to UL, and a buffer slot assigned between the DL and UL slots. In this way, the number of consecutive DL slots and the number of consecutive UL slots within the transmission period are set in advance. The buffer slot is also assigned consecutive DL symbols, consecutive UL symbols, and blank symbols that function as guards between them. Note that the SSB shown in Figure 4 shows a configuration in which 3 symbols are assigned to DL symbols and 3 symbols are assigned to UP symbols, and 8 symbols are assigned as guards.

[0020] From the above, if the master station device 10 can detect the index number of an SSB placed at a specific position in a radio frame, it can estimate the position within the transmission period of that SSB. Furthermore, if the master station device 10 knows the DL / UL configuration information of the TDD system, it can estimate the DL / UL switching timing within the transmission period relative to the placement position of the SSB.

[0021] In the following description, the direction of communication from the base station 50 to the terminal device 60 is referred to as the downstream direction (downlink), and the opposite direction is referred to as the upstream direction (uplink). Correspondingly, a signal transmitted in the downstream direction is referred to as a "DL signal," and a signal transmitted in the upstream direction is referred to as a "UL signal."

[0022] Furthermore, a downstream signal transmitted in the form of a frame is called a "downstream frame," and an upstream signal transmitted in the form of a frame is called an "upstream frame." Furthermore, the upstream side of a device may be referred to as the "upstream" side, and the downstream side as the "downstream." Correspondingly, a device connected to the upstream side of a device may be referred to as the "upstream device," and a device connected to the downstream side may be referred to as the "downstream device."

[0023] For example, the master station device 10 is a higher-level device than the relay device 20 and the slave station device 30, and the relay device 20 is a higher-level device than the slave station device 30. Conversely, the relay device 20 and the slave station device 30 are lower-level devices than the master station device 10, and the slave station device 30 is a lower-level device than the master station device 10 and the relay device 20.

[0024] FIG. 5 is a diagram illustrating an example of the functional configuration of the master station device 10 according to the first embodiment. The master station device 10 includes a central processing unit (CPU), memory, auxiliary storage device, and other components connected via a bus, and executes a program. The master station device 10 includes a high-level input / output unit 11, a low-level input / output unit 12, a downlink processing unit 13, an uplink processing unit 14, and a control unit 15 through the execution of the program. Note that all or part of the functions of the master station device 10 may be implemented using hardware such as an application-specific integrated circuit (ASIC), a programmable logic device (PLD), or a field-programmable gate array (FPGA). The program may be recorded on a computer-readable recording medium. Examples of the computer-readable recording medium include portable media such as a flexible disk, a magneto-optical disk, a ROM, and a CD-ROM, and storage devices such as a hard disk built into a computer system. The program may be transmitted via a telecommunications line.

[0025] The upper input / output unit 11 is a communication interface that inputs and outputs radio signals to and from a higher-level device of the parent station device 10. Specifically, the upper input / output unit 11 is a communication interface that inputs and outputs radio signals to and from the base station 50 via a coaxial cable. The upper input / output unit 11 outputs DL signals received from the base station 50 to the downlink processing unit 13, and outputs UL signals input from the uplink processing unit 14 to the base station 50.

[0026] The lower-side input / output unit 12 is a communication interface for inputting and outputting radio signals to and from lower-level devices of the parent station device 10. Specifically, the lower-side input / output unit 12 is a communication interface for inputting and outputting radio signals to and from the child station device 30. The lower-side input / output unit 12 outputs UL signals received from the child station device 30 to the uplink processing unit 14, and outputs DL signals input from the downlink processing unit 13 to the child station device 30.

[0027] The downlink processing unit 13 executes a process (hereinafter referred to as "DL processing") in which the master station device 10 outputs a DL signal received from a higher-level device to a lower-level device. Specifically, the DL processing of the master station device 10 includes an AD (Analog to Digital) conversion process for the DL signal received from the base station 50, a mapping process for associating the digital signal with a frame, and the like. The downlink processing unit 13 outputs a downstream frame associated with the DL signal in the DL processing to the lower-level input / output unit 12.

[0028] The uplink processing unit 14 executes a process (hereinafter referred to as "UL processing") in which the master station device 10 outputs an UL signal received from a lower-level device to a higher-level device. Specifically, the UL processing of the master station device 10 includes a demapping process for acquiring an UL signal from an upstream frame received from the relay device 20 or the slave station device 30, and a digital-to-analog (DA) conversion process for the UL signal acquired by the demapping process. The uplink processing unit 14 outputs the UL signal converted into an analog signal in the UL processing to the upper-level input / output unit 11.

[0029] The control unit 15 has a function of switching between upstream communication and downstream communication in the master station device 10. Specifically, the control unit 15 has a function of detecting a switch between upstream communication and downstream communication, and switches between DL processing and UL processing (transmission operation) at the timing when the control unit 15 detects a switch between upstream communication and downstream communication.

[0030] 6 is a diagram showing an example of the functional configuration of the control unit 15 in the first embodiment. The control unit 15 includes a switching timing generation unit 153 and a switching unit 154.

[0031] The switching timing generation unit 153 estimates the UL period or the DL period and notifies the timing of switching between the UL processing and the DL processing. Specifically, the switching timing generation unit 153 notifies the start timing of the estimated UL period or the DL period. The start timing may be notified as the start time of the UL period or the DL period, or may be notified as the elapsed time from the current time. Furthermore, the notification of the start timing may notify the arrival of the start timing.

[0032] The switching unit 154 switches between the UL process and the DL process at the switching timing notified by the switching timing generation unit 153 .

[0033] 7 is a diagram showing an example of the functional configuration of the switching timing generation unit 153 according to the first embodiment. The switching timing generation unit 153 includes a signal receiving unit 1001, a time waveform calculation unit 1002, an FFT (Fast Fourier Transform) unit 1014, a frequency waveform calculation unit 1003, a switching timing estimation unit 1018, an RF detector 1019, a synchronization signal power calculation unit 1020, and a power display unit 1021. The RF detector 1019, the synchronization signal power calculation unit 1020, and the power display unit 1021 do not necessarily have to be included in the switching timing generation unit 153, but only need to be included in at least the control unit 15 or the master station 10.

[0034] The signal receiving unit 1001 includes an ADC unit 1010, a carrier frequency conversion unit 1011, and a sampling rate conversion unit 1012. The signal receiving unit 1001 receives an OFDM signal and converts it into a baseband time-domain waveform signal. More specifically, the signal receiving unit 1001 receives a radio frame including an SSB. That is, the signal receiving unit 1001 receives an SSB including a PSS, an SSS, and a PBCH including a DMRS.

[0035] The ADC unit 1010 converts the input analog signal into a digital signal and outputs it to the carrier frequency conversion unit 1011. The carrier frequency conversion unit 1011 down-converts the frequency of the input digital signal into a baseband signal and outputs it to the sampling rate conversion unit 1012. The sampling rate conversion unit 1012 converts the sampling rate of the input baseband signal to generate a baseband time-domain waveform signal, which is a baseband time-domain waveform signal. The sampling rate conversion unit 1012 then outputs the baseband time-domain waveform signal to the PSS detection unit 1013 and the FFT unit 1014.

[0036] The time waveform calculation unit 1002 includes a PSS detection unit 1013. The time waveform calculation unit 1002 extracts a portion of the baseband time domain waveform signal that is the output of the signal receiving unit 1001, and calculates a correlation value between the extracted signal and a known signal.

[0037] The PSS detection unit 1013 detects the PSS signal included in the time domain waveform signal. More specifically, the PSS detection unit 1013 detects the PSS signal placed at the beginning of the SSB from the baseband signal after sampling rate conversion, and outputs the detected timing as SSB timing to the FFT unit 1014. The PSS detection unit 1013 also determines which of multiple PSS code sequences the detected PSS signal corresponds to, and outputs this to the SSS detection unit 1016 as NID2, which is a cell identifier in the physical layer.

[0038] The FFT unit 1014 performs an FFT on the time-domain waveform signal output from the signal receiving unit 1001. More specifically, the FFT unit 1014 extracts the SSB from the baseband time-domain waveform signal after sampling rate conversion based on the input SSB timing, and performs a Fourier transform on it. The FFT unit 1014 then outputs the SSB frequency-domain waveform signal obtained by the Fourier transform to the waveform equalization unit 1015 and the synchronization signal power calculation unit 1020.

[0039] The frequency waveform calculation unit 1003 includes a waveform equalization unit 1015, an SSS detection unit 1016, and a DMRS detection unit 1017. The frequency waveform calculation unit 1003 extracts a portion of the frequency axis waveform signal that is the output of the FFT unit 1014, and calculates the degree of similarity between the extracted signal and a known signal.

[0040] The waveform equalizer 1015 corrects at least one of the amplitude and phase distortions on the IQ complex plane for the frequency axis waveform signal. More specifically, the waveform equalizer 1015 corrects at least one of the amplitude and phase distortions on the IQ complex plane for the input SSB frequency axis waveform signal, and outputs the corrected SSB symbol to the SSS detector 1016 and the DMRS detector 1017.

[0041] The SSS detection unit 1016 detects the SSS signal included in the frequency domain waveform signal. More specifically, the SSS detection unit 1016 detects the SSS signal from the SSB frequency domain waveform signal waveform equalized by the waveform equalization unit 1015. The SSS detection unit 1016 also determines which of multiple SSS sequences the detected SSS signal corresponds to. The SSS detection unit 1016 then outputs the determined SSS signal to the DMRS detection unit 1017 as NID1, which indicates the group of physical layer cell identifiers.

[0042] The DMRS detector 1017 detects a DMRS signal included in the frequency domain waveform signal. More specifically, the DMRS detector 1017 detects the DMRS signal from the frequency domain waveform signal of the waveform-equalized SSB. The DMRS detector 1017 determines which of multiple DMRS sequences the detected DMRS signal corresponds to. The DMRS detector 1017 then outputs an ibar_SSB corresponding to the DMRS sequence to the switching timing estimator 1018. The switching timing estimator 1018 estimates the timing of switching between uplink and downlink communications in the device itself based on the calculation result of the frequency waveform calculator 1003. More specifically, the switching timing estimator 1018 estimates the position within the transmission period of the SSB from the input ibar_SSB. The switching timing estimation unit 1018 estimates the DL / UL switching timing within a transmission period from the arrangement position of the SSB to be estimated and known DL / UL configuration information in the TDD system.

[0043] The RF (Radio Frequency) detector 1019 measures various indicators of the wireless signal input from the upper input / output unit 11. For example, the RF detector 1019 converts the input wireless signal power into a DC voltage proportional to a logarithm and outputs the converted DC voltage. The RF detector 1019 outputs the measured power (hereinafter referred to as RF detector power) to the power display unit 1021.

[0044] The synchronization signal power calculation unit 1020 extracts a portion of the frequency axis waveform signal that is the output of the FFT unit 1014, and calculates the power of the extracted frequency waveform signal. There are multiple definitions of signal power within a synchronization signal (SSB). For example, in the case of the SSB arrangement pattern in the radio frame shown in Figure 3, the synchronization signal power calculation unit 1020 extracts the signal of a defined resource element (RE) from the synchronization signal defined in Figure 3, and calculates only the power of the extracted portion. The synchronization signal power calculation unit 1020 outputs the calculated power value (hereinafter referred to as synchronization signal power) to the power display unit 1021.

[0045] The power display unit 1021 acquires the RF detector power output from the RF detector 1019 and the synchronization signal power output from the synchronization signal power calculation unit 1020. The power display unit 1021 controls an external output device to display the calculation results. For example, the external output device is a monitor, a mobile terminal, or the like. Note that the power display unit 1021 may be an output device such as a monitor, in which case the power display unit 1021 displays the acquired calculation results.

[0046] Furthermore, the power display unit 1021 switches between displaying and hiding the synchronization signal power depending on the synchronization status of the switching timing estimation unit 1018. For example, when the synchronization status of the switching timing estimation unit 1018 is in an asynchronous state, the power display unit 1021 hides the value of the synchronization signal power on the external output device. When the synchronization status of the switching timing estimation unit 1018 becomes in a synchronous state, the power display unit 1021 controls the value of the synchronization signal power to be switched from hidden to displayed. Details of the screen display of the synchronization signal power will be described later.

[0047] Furthermore, the power display unit 1021 switches between displaying and hiding the level determination result depending on the synchronization status of the switching timing estimation unit 1018. For example, when the synchronization status of the switching timing estimation unit 1018 is in an asynchronous state, the power display unit 1021 hides the level determination result on the external output device. When the synchronization status of the switching timing estimation unit 1018 becomes in a synchronous state, the power display unit 1021 controls the level determination result to be switched from hidden to displayed. Details of the screen display of the level determination result will be described later.

[0048] 8 is a diagram illustrating an example of the functional configuration of the PSS detection unit 1013 according to the first embodiment. The PSS detection unit 1013 includes a time signal extraction unit 1131, a PSS generation unit 1132, a correlation calculation unit 1133, and an NID2 detection unit 1134.

[0049] The time signal extraction unit 1131 extracts a portion of the time domain waveform signal. More specifically, the time signal extraction unit 1131 extracts data having a length of the OFDM symbol period from the input baseband time domain waveform signal and outputs the data to the correlation calculation unit 1133. That is, the time signal extraction unit 1131 outputs a portion of the baseband time domain waveform signal to the correlation calculation unit 1133.

[0050] The PSS generation unit 1132 outputs a plurality of PSS code sequences of the PSS signal and code sequence numbers that identify the PSS code sequences. More specifically, the PSS generation unit 1132 outputs the plurality of PSS code sequences as PSS sequences to the correlation calculation unit 1133. The PSS generation unit 1132 also outputs a PSS index, which is a code sequence number that identifies the PSS code sequence, to the NID2 detection unit 1134.

[0051] The correlation calculation unit 1133 performs a correlation calculation between the time domain waveform signal output from the time signal extraction unit 1131 and the PSS sequence, which is the PSS code sequence from the PSS generation unit 1132, and outputs a correlation value. The correlation calculation unit 1133 is an example of a first correlation calculation unit. That is, the correlation calculation unit 1133 performs a correlation calculation between the baseband time domain waveform signal input from the time signal extraction unit 1131 and the PSS sequence, and outputs the correlation value, which is the calculation result, to the NID2 detection unit 1134.

[0052] The NID2 detection unit 1134 outputs the timing within a predetermined time range at which the correlation value calculated by the correlation calculation unit 1133 is highest as the SSB timing, and outputs the PSS sequence, which is the PSS code sequence number corresponding to the PSS code sequence with the highest correlation value, as NID2, which is the cell identifier of the physical layer. More specifically, the NID2 detection unit 1134 outputs the timing within a predetermined time range at which the input correlation value is highest as the SSB timing. Furthermore, the NID2 detection unit 1134 outputs the PSS index corresponding to the PSS sequence with the highest correlation value as NID2, which is the cell identifier of the physical layer.

[0053] 9 is a diagram illustrating an example of the functional configuration of the SSS detection unit 1016 according to the first embodiment. The SSS detection unit 1016 includes an SSS extraction unit 1161, an SSS generation unit 1162, a data determination unit 1163, a comparison operation unit 1164, and an NID1 detection unit 1165.

[0054] The SSS extraction unit 1161 extracts the frequency components in which the SSS signal is allocated from the frequency axis waveform signal. More specifically, the SSS extraction unit 1161 extracts the frequency components in which the SSS signal is allocated from the SSB symbol, which is the input frequency axis waveform signal after waveform equalization correction, and outputs the extracted frequency components to the data determination unit 1163. That is, the SSS extraction unit 1161 outputs the frequency components of the SSS signal.

[0055] The SSS generation unit 1162 outputs a plurality of SSS sequences corresponding to NID2, which is a physical layer cell identifier output from the PSS detection unit 1013, and an SSS index that identifies the SSS sequences. More specifically, the SSS generation unit 1162 generates a plurality of SSS code series based on the input NID2, and outputs these as SSS sequences to the comparison operation unit 1164. The SSS generation unit 1162 also outputs the SSS index that identifies the SSS sequence to the NID1 detection unit 1165.

[0056] The data determination unit 1163 determines demodulated data corresponding to the IQ complex coordinate position of the SSS signal output from the SSS extraction unit 1161, and outputs a series of data determined for the entire SSS signal as an SSS sequence to the comparison operation unit 1164. The data determination unit 1163 is an example of a first data determination unit.

[0057] The comparison operation unit 1164 compares the SSS sequence from the data determination unit 1163 with the SSS sequence from the SSS generation unit 1162, and outputs the number of matches as a comparison result to the NID1 detection unit 1165. The comparison operation unit 1164 is an example of a first comparison operation unit. The comparison operation unit 1164 may also output a degree of similarity indicating the degree of similarity between the SSS sequence from the data determination unit 1163 and the SSS sequence from the SSS generation unit 1162 to the NID1 detection unit 1165.

[0058] The NID1 detection unit 1165 determines the SSS sequence with the highest number of matches from the comparison results output by the comparison operation unit 1164. The NID1 detection unit 1165 then outputs the SSS index corresponding to the SSS sequence with the highest number of matches as NID1 indicating a group of cell identifiers in the physical layer. The NID1 detection unit 1165 is an example of a first NID1 detection unit.

[0059] 10 is a diagram illustrating an example of the functional configuration of the DMRS detector 1017 according to the first embodiment. The DMRS detector 1017 includes a DMRS extractor 1171, a DMRS generator 1172, a data determiner 1173, a comparison calculator 1174, and an ibar_SSB detector 1175.

[0060] The DMRS extraction unit 1171 extracts frequency components in which the DMRS signal is allocated from the frequency axis waveform signal. More specifically, the DMRS extraction unit 1171 extracts frequency components in which the DMRS signal is allocated from the SSB symbol, which is the input frequency axis waveform signal after waveform equalization correction, and outputs the extracted frequency components to the data determination unit 1173. That is, the DMRS extraction unit 1171 outputs the frequency components of the DMRS signal.

[0061] The DMRS generation unit 1172 outputs a plurality of DMRS sequences corresponding to NID1 indicating a group of physical layer cell identifiers, which is the output of the SSS detection unit 1016, and an ibar_SSB index that identifies the DMRS sequences. More specifically, the DMRS generation unit 1172 generates a plurality of code sequences based on the input NID1, and outputs the code sequences as DMRS sequences to the comparison operation unit 1174. The DMRS generation unit 1172 also outputs a DMRS index that identifies the DMRS sequence to the ibar_SSB detection unit 1175.

[0062] The data determination unit 1173 determines demodulated data corresponding to the IQ complex coordinate position of the DMRS signal output from the DMRS extraction unit 1171, and outputs a series of data determined for the entire DMRS signal as a DMRS sequence to the comparison operation unit 1174. The data determination unit 1173 is an example of a second data determination unit.

[0063] The comparison operation unit 1174 compares the DMRS sequence from the data determination unit 1173 with the DMRS sequence from the DMRS generation unit 1172, and outputs the number of matches as a comparison result to the ibar_SSB detection unit 1175. The comparison operation unit 1174 is an example of a third comparison operation unit.

[0064] The ibar_SSB detector 1175 determines the DMRS sequence with the highest number of matches from the comparison results output by the comparison calculator 1174. The ibar_SSB detector 1175 then outputs, as ibar_SSB, the ibar_SSB index corresponding to the DMRS sequence with the highest number of matches. The ibar_SSB detector 1175 is an example of a first ibar_SSB detector.

[0065] 11 is a diagram showing an example of the functional configuration of the synchronization signal power calculation unit 1020 according to the first embodiment. The synchronization signal power calculation unit 1020 includes an RB extraction unit 1022 and a power calculation unit 1023.

[0066] The RB extraction unit 1022 acquires the frequency axis waveform signal output from the FFT unit 1014. The RB extraction unit 1022 extracts specific resource block (RB) data from the acquired frequency axis waveform based on the defined resource elements. The RB extraction unit 1022 outputs the extracted specific resource block data to the power calculation unit 1023.

[0067] The power calculation unit 1023 acquires the specific resource block data output by the RB extraction unit 1022. The power calculation unit 1023 determines the timing of the resource element for which power should be calculated from the SSB timing (the arrangement position within the SSB transmission period). The power calculation unit 1023 calculates the synchronization signal power from the specific resource block data and the determined resource element timing. The power calculation unit 1023 outputs the calculated synchronization signal power to the power display unit 1021.

[0068] Next, there will be described several examples of display screens displayed by the power display unit 1021. Fig. 12 is a diagram showing an example of a screen displayed by the power display unit 1021 according to the first embodiment.

[0069] For example, the power display unit 1021 displays RF detector power, synchronization signal power, synchronization status, and level determination as shown in Fig. 12. Note that the information displayed by the power display unit 1021 is not limited to that shown in Fig. 12, and may be set in advance to display information required by the user, etc.

[0070] 12A shows the state before synchronization, immediately after radio waves are emitted from the base station 50. In the state before synchronization, for example, the power display unit 1021 displays the RF detection power as −20 dB and the synchronization status as asynchronous, and controls the display so as to not display the synchronization signal power and the level determination result.

[0071] Figure 12(b) shows a synchronized state where the signal level is outside the range. For example, when the synchronization status changes from the pre-synchronization state shown in Figure 12(a) to synchronized, it becomes possible to display the synchronization signal power and level judgment result. In the case of Figure 12(b), the appropriate level is assumed to be between +3 dB and -3 dB, so the level judgment result is displayed as NG.

[0072] 12(c) shows a synchronized state within the signal level range. For example, since FIG. 12(c) shows the result after adjusting the input level from base station 50, the synchronization signal power is within the appropriate level range, and the level judgment result is displayed as OK.

[0073] Fig. 12(d) shows a synchronized state, within the signal level range, where traffic has begun to flow from base station 50. For example, in Fig. 12(d), although the RF detector power is higher than the RF detector power in Fig. 12(c), the synchronization signal power is not different from the synchronization signal power in Fig. 12(c), so it is within the appropriate level range, and the level determination result is displayed as OK.

[0074] Next, the order of processing for determining the display in Fig. 12 will be described with reference to the flowchart in Fig. 13. Fig. 13 is a flowchart showing an example of synchronization signal power calculation processing and power display processing according to the first embodiment.

[0075] When the synchronization signal power calculation process and power display process are started, the synchronization signal power calculation unit 1020 determines whether the synchronization status is in a synchronized state (step S1). If the synchronization signal power calculation unit 1020 determines that the synchronization status is in a synchronized state (step S1), it calculates the synchronization signal power, and controls the power display unit 1021 to display the calculated synchronization signal power on an external output device or the like (step S2).

[0076] Next, the power display unit 1021 determines whether the synchronization signal power is within a predetermined appropriate level range (step S3). If the power display unit 1021 determines that the synchronization signal power is within the appropriate level range (step S3, YES), it displays "OK" as the level determination result on an external output device or the like (step S4).

[0077] Furthermore, if the power display unit 1021 determines that the synchronization signal power is outside the appropriate level range (step S3, NO), it causes the external output device to display NG as the level determination result (step S5). Note that the character string displayed on the screen as the level determination result is not limited to OK or NG, and may be any other character string, etc., as long as it is visually recognizable that the synchronization signal power is within the appropriate level range or is outside the appropriate level range.

[0078] Furthermore, when the synchronization signal power calculation unit 1020 determines that the synchronization status is not synchronized, i.e., is in an asynchronous state (step S1), it sends a signal indicating the asynchronous state to the power display unit 1021, and the power display unit 1021 displays or does not display on an external output device, etc., that the synchronization signal power has not been calculated (step S6).

[0079] Furthermore, the power display unit 1021 displays on an external output device or the like that the level determination result has not been calculated, or does not display the display (step S7). After the processes of steps S4, S5, and S7 are executed, the synchronized power calculation process and the power display process are terminated. Note that the synchronized power calculation process and the power display process are executed at any timing and repeatedly executed.

[0080] According to the communication device of this embodiment, by calculating the synchronization signal power and displaying the synchronization signal power and the level judgment result, in a 5G NR compatible distributed antenna system, it becomes possible to visually recognize the appropriate parent unit input level, which could not be determined from the input level from the base station measured by an RF detector, and it becomes possible to adjust to an appropriate parent unit input level.

[0081] [Second Embodiment] In the second embodiment, an averaging processing unit 1024 is added to the synchronization signal power calculation unit 1020, and other functional configurations are the same as those in the first embodiment, so description thereof will be omitted. Fig. 14 is a diagram showing another example of the functional configuration of the synchronization signal power calculation unit according to the second embodiment.

[0082] The averaging unit 1024 averages the multiple synchronization signal power values ​​output by the power calculation unit 1023 and outputs the average synchronization signal power. For example, if the synchronization signal has a period of 20 ms, the averaging unit 1024 acquires the synchronization signal power output every 20 ms from the power calculation unit 1023, calculates the average synchronization signal power according to the number of acquired synchronization signal power values, and outputs the average synchronization signal power.

[0083] According to the communication device of this embodiment, the averaging processing unit calculates the average value of multiple synchronization signal powers, which makes it possible to suppress sudden fluctuations in the synchronization signal power and improve the accuracy of the calculation results of the synchronization signal power calculation unit.

[0084] [Third Embodiment] In the third embodiment, an offset processing unit 1025 is added to the synchronization signal power calculation unit 1020, and the other functional configurations are the same as those in the first and second embodiments, so description thereof will be omitted. Fig. 15 is a diagram showing another example of the functional configuration of the synchronization signal power calculation unit according to the third embodiment.

[0085] For example, it is known that even if the signal bandwidth changes, the synchronization signal bandwidth does not change, but the RF detector power does. In other words, the ratio of the RF detector power to the synchronization signal power changes depending on the signal bandwidth. In conventional distributed antenna systems, adjustments are made based on the RF detector power value during full traffic. Therefore, to align the synchronization signal power result with the level value of the conventional distributed antenna system, an offset function according to the signal bandwidth is required.

[0086] Therefore, the offset processing unit 1025 performs offset processing on the average synchronization signal power output from the averaging processing unit 1024. The offset processing unit 1025 is configured so that the offset amount can be changed by a monitoring and control terminal, which is a higher-level device. Furthermore, it is assumed that the offset processing by the offset processing unit 1025 will be used when the same port is used with different signal bandwidths. By having the offset function, when a user or the like is visually checking the synchronization signal power on a monitor, it is possible to display RF detector power equivalent to that during full traffic, thereby improving usability.

[0087] That is, the communication device, control method, and program of the present embodiment allow the user to recognize the appropriate power.

[0088] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are intended to be included within the scope and spirit of the invention, as well as within the scope of the invention and its equivalents as defined in the claims.

Claims

1. In a distributed antenna system comprising a master station connected to a base station and one or more slave station devices which relay signals between a terminal device communicating with the base station and the master station, a communications device which functions as the master station or the slave station and receives an OFDM signal transmitted by a time division multiplexing system comprises: a signal receiving unit which receives the OFDM signal and converts it into a baseband time axis waveform signal; a time waveform calculation unit which extracts a portion of the time axis waveform signal which is the output of the signal receiving unit and calculates a correlation value between the extracted signal and a known signal; an FFT unit which performs an FFT on the time axis waveform signal which is the output of the signal receiving unit; a frequency waveform calculation unit which extracts a portion of the frequency axis waveform signal which is the output of the FFT unit and calculates the degree of similarity between the extracted signal and a known signal; a switch timing estimation unit which estimates a switch timing between uplink and downlink communications in the own device based on a result of calculation by the frequency waveform calculation unit; and a synchronization signal power calculation unit which extracts a portion of the frequency axis waveform signal which is the output of the FFT unit and calculates the power of the extracted frequency axis waveform signal. a power display unit that displays a calculation result of the synchronization signal power calculation unit.

2. The communication device according to claim 1, wherein said synchronization signal power calculation section includes an averaging processing section that averages an output of said synchronization signal power calculation section.

3. The communication device according to claim 2, wherein said synchronization signal power calculation section includes an offset processing section that offsets said power output from said synchronization signal power calculation section.

4. The communication device according to claim 1, wherein the power display unit switches between displaying and not displaying the power and level determination in accordance with a synchronization status of a switching timing estimation unit.

5. In a distributed antenna system comprising a master station connected to a base station and one or more slave station devices that relay signals between a terminal device communicating with the base station and the master station, a control method for a communication device that functions as the master station or the slave station and receives an OFDM signal transmitted by a time division multiplexing system, the control method comprising: receiving the OFDM signal and converting it to a baseband time axis waveform signal; extracting a portion of the time axis waveform signal and calculating a correlation value between the extracted signal and a known signal; performing an FFT on the time axis waveform signal; extracting a portion of the frequency axis waveform signal on which the FFT has been performed and calculating a similarity between the extracted signal and a known signal; estimating a switching timing between uplink and downlink communications in the device based on a result of the calculation of the similarity; extracting a portion of the frequency axis waveform signal and calculating the power of the extracted frequency axis waveform signal; and displaying the calculation result of the power.

6. A program for causing a computer to execute the control method according to claim 5.

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