communication equipment

Abstract

The present invention discloses a communication device that reduces the time required for setting up a cancellation signal. The communication device includes first, second, and third generation units, a sharing unit, a synthesis unit, a detection unit, first and second control units, and a selection unit. The first control unit controls the second generation unit to generate a cancellation signal using a gain and phase shift amount corresponding to an error level detected by the detection unit. The third generation unit generates multiple prediction models associated with predicted error level variation patterns and gain and phase shift amounts based on multiple recordings of error level variation patterns detected during a first period after the error level variation begins and the gain and phase shift amounts determined after the multiple variations converge. The selection unit selects one of the multiple prediction models based on the error level variation pattern after the variation begins. The second control unit controls the second generation unit to generate a cancellation signal using the gain and phase shift amount represented by the selected prediction model.

Description

[0001] This application claims priority from Japanese patent application No. JP2021-105061, filed on Jun. 24, 2021, and cites the contents of the aforementioned application, the disclosure of which is hereby incorporated by reference in its entirety. Technical Field

[0002] An embodiment of the present invention relates to a communication device. Background Art

[0003] In communications devices that share a common antenna for both transmission and reception, a portion of the transmitted signal may overlap with the received signal and enter the receiving system. This transmitted signal component superimposed on the received signal is a self-interference signal, potentially causing saturation of the receiving system and increased noise, leading to a decrease in communication quality.

[0004] Therefore, a technique is known in which a cancellation signal having a phase opposite to that of a self-interference signal is generated from a transmission signal and the self-interference signal is canceled using the cancellation signal.

[0005] However, the setting of the gain and phase shift amount for generating an appropriate cancellation signal is currently performed by sweeping the phase shift amount and gain, and this setting requires a long time.

[0006] In view of this situation, it is desired to shorten the time required for setting up the generation of the cancellation signal. Summary of the Invention

[0007] In view of the above problems, the present invention aims to provide a communication device capable of shortening the time required for setting up a cancellation signal.

[0008] To solve the above-mentioned problem, an embodiment of the present invention provides a communication device including a first generating unit, a common unit, a second generating unit, a synthesizing unit, a detecting unit, a first controlling unit, a third generating unit, a selecting unit and a second controlling unit. The first generating unit generates a transmission signal for wireless transmission; the common unit inputs the transmission signal generated by the first generating unit from the input end and outputs it from the input-output end, and outputs the signal input from the input-output end from the output end; the second generating unit changes the amplitude and phase of the transmission signal generated by the first generating unit and generates an elimination signal; the synthesizing unit synthesizes the elimination signal into the signal output from the output end; the detecting unit detects the error level of the self-interference signal contained in the output signal from the output end with respect to the elimination signal; the first controlling unit controls the second generating unit to generate the elimination signal using a gain and a phase shift amount determined in accordance with the error level detected by the detecting unit; the third generating unit generates the elimination signal within a predetermined first period after the error level change detected by the detecting unit begins. The variation graphs of the error level detected by the detection unit are recorded multiple times during the period, and based on the gains and phase shift amounts determined by the first control unit after the variation of the error level converges during the multiple times and the multiple variation graphs recorded above, a plurality of prediction models are generated, which are associated with the variation graphs of the error level predicted for the second period as an initial part of the first period and the gain and phase shift amounts after the variation converges; a selection unit selects one of the multiple prediction models, and the multiple prediction models are generated by the third generation unit based on the variation graph detected by the detection unit in the second period after the variation of the error level detected by the detection unit starts; and a second control unit controls the second generation unit to generate an elimination signal using the gain and phase shift amount represented by the prediction model selected by the selection unit.

[0009] According to the above-described communication device, it is possible to omit scanning of the gain and the phase shift amount, thereby shortening the time required for setting the generation of the cancellation signal.

[0010] In the above-mentioned communication device, the second control unit controls the second generation unit so as to change the gain and the phase shift amount within a limited range that is a part of the adjustable range of the gain and the phase shift amount in the second generation unit, and generates the cancellation signal using the gain and the phase determined based on the error levels respectively detected by the detection unit.

[0011] According to the above-described communication device, since the error level is detected only within a limited range, the time required for scanning can be shortened compared to scanning the entire range.

[0012] In the above-mentioned communication device, the second control unit controls the second generating unit so that when the error level detected by the detection unit deviates from the first range with respect to the elimination signal generated by the second generating unit using the gain and phase shift amount represented by the prediction model selected by the selection unit, the gain and phase shift amount are changed within the limited range, and the elimination signal is generated using the gain and phase determined based on the error levels respectively detected by the detection unit.

[0013] According to the above-described communication device, it is possible to readjust the gain and shift amount of the cancellation signal generated based on the prediction model.

[0014] In the above-mentioned communication device, the second control unit controls the second generation unit so that when the error level detected by the detection unit deviates from the first range with respect to the elimination signal generated by the second generation unit, the gain and phase shift amount are changed within the limited range, and the elimination signal is generated using the gain and phase determined based on the error levels respectively detected by the detection unit.

[0015] According to the above-described communication device, the gain and phase shift amount can be readjusted for the cancellation signal generated by adjusting the gain and phase shift amount.

[0016] The communication device further includes a detection unit that performs carrier quadrature detection on the synthesized output of the synthesis unit and outputs two-channel received baseband signals, and the detection unit detects the error level based on the signal levels of the two-channel received baseband signals output from the detection unit.

[0017] According to the above-described communication device, the error level can be detected based on the signal levels of the received baseband signals of the two channels.

[0018] In the above-mentioned communication device, the second generating unit includes a variable attenuator for attenuating a transmission signal by a gain corresponding to a gain setting signal, and a variable phase shifter for changing a phase of the transmission signal attenuated by the variable attenuator by a phase shift amount corresponding to a phase shift amount setting signal.

[0019] According to the above-described communication device, a cancellation signal can be generated using the gain setting signal and the phase shift amount setting signal.

[0020] In the above-mentioned communication device, the first control unit controls the second generation unit so that the gain and the phase shift amount vary within the full range of the adjustable range of the gain and the phase shift amount in the second generation unit, and the cancellation signal is generated using the gain and the phase shift amount that minimize the error level detected by the detection unit.

[0021] According to the above-mentioned communication device, it is possible to generate a cancellation signal with a minimum error level.

[0022] In the above-mentioned communication device, the third generating unit obtains the error level at a predetermined time interval, and is able to determine the error level and save it in order. When the amount of change corresponding to each unit time of the error level is smaller than a predetermined threshold value, it is determined that the change has converged, and the gain and phase shift amount are changed within the full range of the adjustable range of the gain and phase shift amount. The gain and phase shift amount with the minimum error level are determined, the saved error level and the determined gain and phase shift amount are associated and the change graph is saved, and multiple change graphs are accumulated until the number of saved change graphs reaches a predetermined number. When the number of accumulated change graphs reaches a predetermined number, multiple prediction models are generated.

[0023] According to the above-described communication device, prediction models can be generated for a plurality of fluctuation patterns.

[0024] In the above-mentioned communication device, the third generating unit generates the plurality of prediction models by associating representative gains and phase shift amounts of the accumulated plurality of variation patterns.

[0025] According to the above-mentioned communication device, it is possible to generate a cancellation signal with a minimum error level.

[0026] In the above-mentioned communication device, the third generation unit generates a plurality of prediction models based on similar variation patterns among the accumulated plurality of variation patterns.

[0027] According to the above-mentioned communication device, a prediction model can be generated for a variation pattern similar to another variation pattern. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a block diagram showing the main circuit configuration of a reading device according to one embodiment;

[0029] Figure 2 It is a flow chart of the learning process;

[0030] Figure 3 This is an example diagram of the changes in the amplitude and phase of the self-interference signal;

[0031] Figure 4 This is an example diagram of the changes in the amplitude and phase of the self-interference signal;

[0032] Figure 5 This is an example diagram of the changes in the amplitude and phase of the self-interference signal;

[0033] Figure 6 is a flow chart of the control process; and

[0034] Figure 7This is a diagram showing an example of a limited range.

[0035] Description of Reference Numerals

[0036] 11 Oscillator 12 Phase shifter 13 DA converter

[0037] 14 Quadrature modulator 15, 26 BPF 16 Power amplifier

[0038] 17, 29 LPF 18 Antenna duplexer 19 Power supply line

[0039] 20 Antenna 21 Variable attenuator 22 Variable phase shifter

[0040] 23 DA Converter 24 Power Combiner 25 Quadrature Detector

[0041] 27 Baseband amplifier 28, 30 AD converter 31 Control unit

[0042] 311 CPU 312 FPGA 313 Memory

[0043] 100 Reading device 200 RFID tag DETAILED DESCRIPTION

[0044] The following describes an embodiment with reference to the accompanying drawings. Furthermore, a reader device for reading data stored on an RFID (Radio Frequency Identification) tag is used as an example. This reader device wirelessly communicates with the RFID tag when reading data and is an example of a communication device. Furthermore, the reader device is portable.

[0045] Figure 1This is a block diagram showing the main circuit configuration of a reader device 100 according to this embodiment. The reader device 100 includes an oscillator 11, a phase shifter 12, a digital-to-analog (DA) converter 13, a quadrature modulator 14, a bandpass filter (BPF) 15, a power amplifier 16, a low-pass filter (LPF) 17, an antenna duplexer 18, a power supply line 19, an antenna 20, a variable attenuator 21, a variable phase shifter 22, a DA converter 23, a power combiner 24, a quadrature detector 25, a BPF 26, a baseband amplifier 27, an analog-to-digital (AD) converter 28, an LPF 29, an AD converter 30, and a control unit 31. The control unit 31 includes a CPU 311, an FPGA (field programmable gate array) 312, and a memory 313. Furthermore, the antenna 20 or the power supply line 19 and the antenna 20 may not be included in the reader 100 but may be a separate structure that can be connected to any device.

[0046] The oscillator 11 generates a sine wave of a preset frequency as a carrier wave.

[0047] The phase shifter 12 outputs a cosine wave as another carrier wave by shifting the phase of the carrier wave generated by the oscillator 11 by 90 degrees.

[0048] The DA converter 13 converts the two-channel transmission baseband signals output in a digital state from the CPU 311 into analog form. In the following, the two-channel transmission baseband signals are referred to as an I signal and a Q signal, respectively.

[0049] The quadrature modulator 14 receives as modulated waves the I and Q signals analogized by the DA converter 13. The quadrature modulator 14 receives as input the carrier waves generated by the oscillator 11 and the carrier wave output from the phase shifter 12 as carrier waves for the I and Q channels, respectively. The quadrature modulator 14 then obtains a transmission signal through quadrature modulation.

[0050] The BPF 15 removes low-frequency components and high-frequency components from the transmission signal obtained by the orthogonal modulator 14 for bandwidth limitation.

[0051] The power amplifier 16 amplifies the power of the transmission signal that has passed through the BPF 15 to a level suitable for wireless transmission.

[0052] The LPF 17 removes harmonic components from the transmission signal amplified by the power amplifier 16 .

[0053] The transmission signal becomes a signal for wireless transmission through the processing of the BPF 15, the power amplifier 16, and the LPF 17. In short, the BPF 15, the power amplifier 16, and the LPF 17 constitute a first generation unit that generates a transmission signal for wireless transmission.

[0054] Antenna duplexer 18 includes an input terminal TI, an input / output terminal TIO, an output terminal TOA, and an output terminal TOB. The transmit signal passing through LPF 17 is input to input terminal TI. Antenna duplexer 18 outputs the transmit signal input to input terminal TI through input / output terminal TIO and output terminal TOB. Antenna duplexer 18 outputs the signal input to input / output terminal TIO through output terminal TOA. The signal output from output terminal TOA of antenna duplexer 18 is a composite of the received signal generated by antenna 20 and a self-interference signal (described later). This signal is hereinafter referred to as simply the received signal. Antenna duplexer 18 is an example of a sharing unit.

[0055] The feed line 19 supplies a transmission signal output from the input / output terminal T10 of the duplexer 18 to the antenna 20. The feed line 19 transmits a reception signal generated by the antenna 20 to the input / output terminal T10 of the duplexer 18.

[0056] The antenna 20 emits radio waves corresponding to the transmission signal supplied via the power supply line 19. The antenna 20 generates an electric signal corresponding to the radio wave from the RFID tag as a received signal. The antenna 20, which transmits and receives radio waves to and from the RFID tag, is connected to the antenna duplexer 18 via the power supply line 19.

[0057] The variable attenuator 21 attenuates the transmission signal output from the output terminal TOB of the antenna duplexer 18 by a gain corresponding to the gain setting signal supplied from the DA converter 23 .

[0058] The variable phase shifter 22 changes the phase of the transmission signal attenuated by the variable attenuator 21 by a phase shift amount corresponding to the phase shift amount setting signal supplied from the DA converter 23. Hereinafter, the transmission signal after the phase shift by the variable phase shifter 22 is referred to as a cancellation signal.

[0059] Furthermore, the variable attenuator 21 and the variable phase shifter 22 realize a function as a second generation unit that generates a cancellation signal.

[0060] The DA converter 23 converts the gain setting data output from the control unit 31 into an analog gain setting signal and supplies it to the variable attenuator 21. The DA converter 23 converts the phase shift setting data output from the control unit 31 into an analog phase shift setting signal and supplies it to the variable phase shifter 22.

[0061] The power combiner 24 combines the power of the cancellation signal output from the variable phase shifter 22 with the reception signal output from the output terminal TOA of the antenna duplexer 18. Thus, the power combiner 24 reduces the self-interference signal included in the reception signal. The power combiner 24 is an example of a combining unit.

[0062] The quadrature detector 25 performs quadrature detection on the received signal output from the power combiner 24 using two carrier waves output from the oscillator 11 and the phase shifter 12, respectively. The quadrature detector 25 outputs the analog received baseband signals of the two channels obtained by the quadrature detection in parallel. In short, the quadrature detector 25 is an example of a detection unit.

[0063] The BPF 26 extracts components of desired frequency bands from the two-channel reception baseband signals output from the quadrature detector 25 .

[0064] The baseband amplifier 27 amplifies the two channels of received baseband signals that have passed through the BPF 26 to a level suitable for digitization by the AD converter 28 .

[0065] The AD converter 28 digitizes the reception baseband signals of the two channels amplified by the baseband amplifier 27 .

[0066] The LPF 29 removes harmonic components contained in the two channels of received baseband signals output from the quadrature detector 25 .

[0067] The AD converter 30 digitizes the two channels of received baseband signals output from the LPF 29 .

[0068] When communicating with the RFID tag 200, the CPU 311 outputs an I signal and a Q signal in a predetermined sequence. The CPU 311 reconstructs the data transmitted from the RFID tag 200 based on the two-channel received signals digitized by the AD converter 28. The CPU 311 performs information processing, described below, for adjusting the gain of the variable attenuator 21 and the phase shift amount of the variable phase shifter 22 based on the two-channel received baseband signals digitized by the AD converter 30.

[0069] FPGA 312 executes pre-programmed signal processing, rapidly performing the various calculations associated with the information processing performed by CPU 311. One of the functions of FPGA 312 is to calculate the error level of the cancellation signal relative to the self-interference signal based on the levels of the two-channel received baseband signals digitized by A / D converter 30. Thus, FPGA 312 functions as a detection unit that detects the error level through calculations based on the levels of the two-channel received baseband signals.

[0070] The memory 313 stores information processing programs describing information processing executed by the CPU 311. The memory 313 stores various data required by the CPU 311 when executing various information processing. The memory 313 stores various data generated or acquired by the CPU 311 when executing various information processing.

[0071] Next, the operation of the reader 100 configured as described above will be described. The operation for reading the RFID tag 200 may also be another known operation, for example, using quadrature modulation as the modulation method for wireless communication. Therefore, the description of this operation will be omitted here, and the operation for adjusting the gain of the variable attenuator 21 and the phase shift amount of the variable phase shifter 22 will be described.

[0072] Before explaining the operation, the self-interference signal will be explained.

[0073] Antenna duplexer 18 is designed to prevent the transmit signal input to input terminal TI from being output from output terminal TOA. However, in actual circuit configuration, it is difficult to completely prevent the transmit signal input from input terminal TI from leaking out of output terminal TOA. Therefore, a portion of the transmit signal input to input terminal TI is output unchanged from output terminal TOA. Furthermore, a portion of the transmit signal output from input / output terminal TIO of antenna duplexer 18 is reflected at the feed point of antenna 20 and transmitted to antenna duplexer 18 via feeder line 19. This reflected signal is output from output terminal TOA due to the function of antenna duplexer 18. As a result, the signal output from output terminal TOA of antenna duplexer 18 contains components of the transmit signal that leaked from input / output terminal TIO instead of being output, and components of the transmit signal that was input to input / output terminal TIO as a reflected signal. The resulting signal, which combines these transmit signal components, constitutes a self-interference signal. Furthermore, the characteristics of the transmit signal reflection at the feed point of antenna 20 vary depending on the environment surrounding antenna 20, such as the proximity of RFID tags 200 and other objects approaching antenna 20. Therefore, the amplitude and phase of the signal reflected at the feeding point of the antenna 20 also vary depending on the environment around the antenna 20. Under this influence, the amplitude and phase of the self-interference signal also vary depending on the environment around the antenna 20.

[0074] Furthermore, the self-interference signal is a signal derived from the transmitted signal. Therefore, by varying the amplitude and phase of the signal branched from the transmitted signal, a signal with the same frequency and amplitude as the self-interference signal but opposite phase can be generated. This signal is then synthesized with the received signal output from the TOA output of the antenna duplexer 18 to cancel out the self-interference signal contained in the received signal. In the reader 100, the cancellation signal, obtained by varying the amplitude and phase in the variable attenuator 21 and the variable phase shifter 22, is synthesized with the received signal output from the TOA output of the antenna duplexer 18 in the power combiner 24, thereby reducing the self-interference signal contained in the received signal.

[0075] Furthermore, the reader device 100 is used to read data from RFID tags 200 attached to items placed at predetermined locations within a warehouse. Therefore, when a worker holding the reader device 100 moves in front of a shelf and repeatedly causes the reader device 100 to read RFID tags 200 attached to items placed on that shelf, there is a possibility that the self-interference signal will change in a similar manner.

[0076] Therefore, the manager or maintenance personnel of the reading device 100 perform operations to make the reading device 100 learn the above-mentioned tendency as an initial setting operation for starting to use the reading device 100 or as a maintenance operation corresponding to changes in shelf allocation.

[0077] In this case, the administrator, maintenance personnel, etc. use the reading device 100 operating in the learning mode to repeat operations that imitate actual reading operations.

[0078] When the reading device 100 is set to the learning mode, the CPU 311 executes a learning process as information processing according to an information processing program stored in the memory 313 .

[0079] The learning mode is set, for example, by inputting an instruction for the learning mode through the operation unit of the reading device 100 .

[0080] Figure 2 It is a flowchart of the learning process.

[0081] As ACT 1, the CPU 311 performs a full-range sweep. For example, the CPU 311 gradually changes the gain and phase shift amount over the entire adjustable range of the gain of the variable attenuator 21 and the adjustable range of the phase shift amount of the variable phase shifter 22, while checking the error level and searching for a gain and phase shift amount combination that minimizes the error level.

[0082] The error level is an indicator of the magnitude of the error between the cancellation signal and the self-interference signal. The error level is obtained by performing a predetermined calculation on the two-channel digital state reception baseband signal output from the AD converter 30 by the FPGA 312. For example, if the signal levels of the two-channel digital state reception baseband signal are expressed as LI and LQ respectively by the FPGA 312, then SQR (LI 2 +LQ 2 ) and calculates the error level. In addition, "SQR" means square root. However, the error level can also be calculated by CPU311 through information processing.

[0083] As ACT 2, the CPU 311 sets the gain and phase shift amount found in ACT 1 to the variable attenuator 21 and the variable phase shifter 22. For example, the CPU 311 outputs gain setting data and phase shift amount setting data corresponding to the gain and phase shift amount found in ACT 1 to the DA converter 23. This gain setting data and phase shift amount setting data are then converted to analog signals by the DA converter 23, and the resulting gain setting signals and phase shift amount setting signals are supplied to the variable attenuator 21 and the variable phase shifter 22. Accordingly, the variable attenuator 21 and the variable phase shifter 22 perform attenuation and phase shifting using the gain and phase shift amount found in ACT 1, thereby generating a cancellation signal.

[0084] Figure 3 、 Figure 4 and Figure 5 It is a diagram showing an example of changes in the amplitude and phase of the self-interference signal.

[0085] Such as these Figures 3 to 5 As shown, the amplitude and phase of the self-interference signal fluctuate due to environmental changes such as movement of the reader 100. Since the CPU 311 does not change the gain and phase shift amount of the variable attenuator 21 and the variable phase shifter 22, the error level fluctuates with the changes in the amplitude and phase of the self-interference signal.

[0086] As ACT3, the CPU 311 waits for the self-interference signal to change. Then, when the error level is greater than or equal to a predetermined first threshold, the CPU 311 determines that the self-interference signal has changed and determines YES, and proceeds to ACT4. The CPU 311 determines that, for example, Figure 3 The moment of TAA, Figure 4 Time TBA, or Figure 5 The first threshold value may be arbitrarily set by a designer of the reader 100 or a creator of the information processing program.

[0087] As ACT 4, the CPU 311 starts sampling and recording the error level. For example, the CPU 311 acquires the error level from the FPGA 312 at predetermined time intervals and stores the acquired error level in a manner that allows the acquisition order to be determined.

[0088] As ACT 5, the CPU 311 checks whether the variation of the self-interference signal has converged. For example, if the variation per unit time of the error level is smaller than a predetermined second threshold, the CPU 311 determines YES as the variation has converged and proceeds to ACT 6. Figure 3 The moment TAC, Figure 4 Time TBC, or Figure 5 The second threshold value can be arbitrarily set by the designer of the reading device 100 or the creator of the information processing program.

[0089] As ACT 6, the CPU 311 ends the sampling record. Figure 3 During the PAA period, Figure 4 During the period of PAB, or Figure 5 Sampling and recording are performed during the PAC period. In short, the length of the sampling and recording period varies depending on the fluctuation pattern of the self-interference signal. Thus, the sampling and recording periods PAA, PAB, and PAC are pre-set as periods during which fluctuations actually occur. These periods PAA, PAB, and PAC correspond to the first period.

[0090] As ACT 7 , the CPU 311 executes a full-range scan. The specific processing of the CPU 311 here may be the same as the processing exemplified in ACT 1 .

[0091] As ACT 8, the CPU 311 sets the gain and phase shift amount found in ACT 7 to the variable attenuator 21 and the variable phase shifter 22. The specific processing of the CPU 311 here can be the same as the processing illustrated in ACT 2. Then, the CPU 311 sets the gain and phase shift amount found in ACT 7 to the variable attenuator 21 and the variable phase shifter 22. Figure 3 In the case of, the gain determined based on the amplitude AMA is set to the variable attenuator 21, and the phase shift amount determined based on the phase PHA is set to the variable phase shifter 22. In addition, the CPU 311 sets the gain determined based on the amplitude AMA to the variable attenuator 21, and sets the phase shift amount determined based on the phase PHA to the variable phase shifter 22. Figure 4 In the case of , the gain determined based on the amplitude AMB is set to the variable attenuator 21, and the phase shift amount determined based on the phase PHB is set to the variable phase shifter 22. In addition, the CPU 311 sets the gain determined based on the amplitude AMB to the variable attenuator 21, and sets the phase shift amount determined based on the phase PHB to the variable phase shifter 22. Figure 5 In the case of , the gain determined based on the amplitude AMC is set to the variable attenuator 21, and the phase shift amount determined based on the phase PHC is set to the variable phase shifter 22.

[0092] As ACT 9, CPU 311 stores pattern data in memory 313. For example, CPU 311 generates pattern data as data representing the gain and phase shift amount found in ACT 7 in association with the set of error levels sampled and recorded in ACTs 4 to 6, and stores the data in memory 313.

[0093] As ACT 10, the CPU 311 checks whether the learning end condition is met. If the CPU 311 cannot confirm the corresponding situation, it determines NO and returns to the waiting state of ACT 3. In this way, the CPU 311 repeats the processing of ACT 3 to ACT 9, and accumulates a plurality of graphic data in the memory 313.

[0094] The termination condition is determined, for example, when the amount of accumulated graphic data reaches a predetermined amount, as described above. However, the termination condition may be arbitrarily determined by the designer of the reading device 100 or the creator of the information processing program, such as when the amount of graphic data exceeds a predetermined amount and an administrator or maintenance personnel indicates the end of learning. If the termination condition is met, the CPU 311 determines YES in ACT 10 and proceeds to ACT 11.

[0095] As ACT 11, CPU 311 generates multiple prediction models based on the graph data accumulated as described above. For example, the prediction model is data that associates and represents a model of the error level fluctuation graph during a certain period of time during the initial stage of the self-interference signal fluctuation with the gain and phase shift amount. The specific information processing used to generate the prediction model can use well-known processes such as regression methods or k-nearest neighbor algorithms. CPU 311 stores the generated prediction models in memory 313. If prediction models generated during previous learning processes are already stored in memory 313, CPU 311 can overwrite these prediction models with the newly generated prediction models or store the new prediction models in an appended form. Then, when CPU 311 completes generating the prediction models, the learning process ends.

[0096] For example, based on Figure 3 The prediction model is generated by associating a model of a variation graph showing the tendency of the variation graph of the error level during the period from time TAA to time TAB after time TZA with a representative gain and phase shift amount based on the setting tendency of the gain and phase shift amount. Figure 4 The prediction model is generated by associating a model of a variation graph showing the tendency of the variation graph of the error level during the period from time TBA to time TBB after time TZA with a representative gain and phase shift amount based on the setting tendency of the gain and phase shift amount based on a plurality of graphic data similar to the variation graph of the error level during the period PAB. Figure 5A prediction model is generated by associating a variation pattern model representing the trend of the error level variation pattern during the period from time TCA to time TCB after time TZA with gain and phase shift values ​​representative of the gain and phase shift value settings, using multiple pattern data similar to the error level variation pattern during period PAC. In short, the variation pattern model represented in each of the multiple prediction models is associated with a period of the same length, time TZA. Thus, the model period of the prediction variation pattern is pre-set as the length of time TZA from the time the error level variation is detected, corresponding to the second period. Furthermore, time TZA can be arbitrarily set by the designer of the reader 100 or the creator of the information processing program.

[0097] In this manner, by executing the learning process based on the information processing program, the CPU 311 functions as a third generating unit.

[0098] When the reading device 100 is in a normal operating state (normal mode), the CPU 311 executes control processing as information processing for controlling the reduction of the self-interference signal as described above, in accordance with the information processing program stored in the memory 313 .

[0099] The normal mode is set in response to input of an instruction for the normal mode via the operation unit of the reading device 100 , for example.

[0100] Figure 6 It is a flowchart of the control process.

[0101] As ACT 21, the CPU 311 performs a full range scan. The specific processing of the CPU 311 here can also be the same as that of, for example, Figure 2 The processing related to ACT1 in is the same as that illustrated.

[0102] As ACT 22, the CPU 311 sets the gain and phase shift amount found in ACT 21 in the variable attenuator 21 and the variable phase shifter 22. The specific processing of the CPU 311 here can be, for example, Figure 2 The processing related to and illustrated in ACT2 is the same.

[0103] In this manner, by executing the same control processing as ACT 1 and ACT 2 based on the information processing program, the CPU 311 functions as a first control unit.

[0104] As ACT 23, the CPU 311 waits for a change in the self-interference signal. The specific processing of the CPU 311 here can be similar to that of, for example, Figure 2 Then, if a change occurs in the self-interference signal, the CPU 311 determines YES and proceeds to ACT 24.

[0105] As ACT 24, the CPU 311 performs sampling and recording of the error level. The specific processing of the CPU 311 here can be similar to that in the example Figure 2 The processing related to and illustrated in connection with sampling and recording starting from ACT 4 in FIG. However, CPU 311 here limits sampling and recording to a predetermined time. The sampling and recording time is assumed to be, for example, time TZA. However, the sampling and recording time can be arbitrarily set by, for example, the designer of reader 100 or the creator of the information processing program, so that sampling and recording is performed during a portion of the initial period of the self-interference signal fluctuation period.

[0106] As ACT 25, the CPU 311 selects one of the plurality of prediction models generated by the aforementioned learning process and stored in the memory 313 based on the error level variation pattern recorded in ACT 24. For example, the CPU 311 selects a prediction model that represents a variation pattern that is closest to the error level variation pattern recorded in ACT 24. However, the rules for CPU 311 to select a prediction model can be arbitrarily set by, for example, the designer of the reading device 100 or the creator of the information processing program, so as to select a prediction model that represents a variation pattern similar to the error level variation pattern recorded in ACT 24.

[0107] In this manner, by executing control processing based on the information processing program, the CPU 311 functions as a selection unit.

[0108] As ACT 26, the CPU 311 checks whether the variation of the self-interference signal has converged. The specific processing of the CPU 311 here can be similar to that of, for example, Figure 2 The processing is the same as that of ACT5 in . Then, if the variation of the self-interference signal has converged, the CPU 311 determines YES and proceeds to ACT 27 .

[0109] As ACT 27, the CPU 311 sets the gain and phase shift amount indicated by the prediction model selected in ACT 25 in the variable attenuator 21 and the variable phase shifter 22. In this manner, control of the gain and phase shift amount based on the prediction model is hereinafter referred to as primary control.

[0110] In this manner, by executing control processing based on the information processing program, the CPU 311 functions as a second control unit.

[0111] As ACT 28, CPU 311 confirms whether the self-interference signal has been successfully eliminated through the primary control. For example, if the error level is less than a predetermined third threshold, CPU 311 determines that the result is satisfactory and returns to ACT 28. In short, if the self-interference signal has been successfully eliminated through the primary control, CPU 311 maintains the settings used in the primary control. Therefore, the gain and phase shift values ​​represented in the prediction model selected in ACT A 25 are appropriate for the amplitude and phase of the self-interference signal after the variation converges. If the self-interference signal can be successfully eliminated, the original operating state is maintained. Furthermore, the third threshold can be arbitrarily set by, for example, the designer of the reader 100 or the creator of the information processing program.

[0112] However, there is a possibility that the gain and phase shift amount represented by the prediction model selected in ACT A25 cannot be guaranteed to match the amplitude and phase of the self-interference signal after the fluctuation converges, and the cancellation signal generated under primary control may not be able to fully cancel the self-interference signal. In addition, there are cases where the self-interference signal fluctuates while the operating state in which the self-interference signal can be effectively canceled is maintained as described above, and the self-interference signal cannot be fully canceled. In these cases, for example, if the error level is greater than or equal to the third threshold, the CPU 311 determines "NO" in ACT 28 and proceeds to ACT 29.

[0113] As ACT 29, CPU 311 determines whether the self-interference signal cancellation is unsatisfactory. For example, if the error level is greater than or equal to a predetermined fourth threshold, CPU 311 determines it as unsatisfactory and returns to ACT 21 with a YES judgment. Furthermore, the fourth threshold can be arbitrarily set by, for example, the designer of the reader 100 or the creator of the information processing program. However, the fourth threshold is greater than the third threshold.

[0114] In this way, when the error level becomes equal to or greater than the fourth threshold and the signal offset is eliminated, the CPU 311 repeats the steps after ACT 21 to re-adjust the gain and phase shift amount based on the result of the full-range scan.

[0115] If the error level is not too large and is smaller than the fourth threshold value, for example, the CPU 311 determines NO in ACT 29 as not being a cancellation failure and proceeds to ACT 30 .

[0116] As ACT 30, CPU 311 executes a limited range scan. A limited range scan targets a limited range that is narrower than the full range scan. For example, CPU 311 gradually changes the gain and phase shift amount within the limited range while checking the error level, and finds the gain and phase shift amount combination that minimizes the error level.

[0117] As ACT 31, the CPU 311 sets the gain and phase shift amount found in ACT 30 in the variable attenuator 21 and the variable phase shifter 22. Such control of the gain and phase shift amount by limited range scanning is hereinafter referred to as secondary control.

[0118] In this way, the CPU 311 performs the secondary control when the error level is smaller than the third threshold value, and the range of the error level smaller than the third threshold value corresponds to the first range.

[0119] Figure 7 This is a diagram showing an example of primary control and secondary control.

[0120] Figure 7 The example is a case where the CPU 311 sets the gain GAA and the phase shift amount SHA in ACT 22. Then, in ACT 27, the CPU 311 performs a control by setting the gain GAB and the phase shift amount SHB represented by the prediction model selected based on the variation graph of the error level with the variation of the self-interference signal. At this time, the limited range RAA is determined based on the gain GAB and the phase shift amount SHB. The limited range RAA is a range within a portion of the scan range RAB in the full range scan. In this embodiment, the gain change range in the limited range RAA is a range from a gain lower than the gain GAB by a first specified value to a gain higher than the gain GAB by a first specified value. In addition, in this embodiment, the phase shift change range in the limited range RAA is a range from a phase shift amount lower than the phase shift amount SHB by a second specified value to a phase shift amount higher than the phase shift amount SHB by a second specified value.

[0121] Furthermore, in ACT 31 , the CPU 311 performs secondary control by setting the gain GAC and the phase shift amount SHC found by the limited range scan related to the limited range RAA.

[0122] Furthermore, the range of change of the gain and phase shift amount related to the limited range RAA can also be arbitrarily set by, for example, the designer of the reading device 100 or the creator of the information processing program. Figure 7 The shape shown in the figure may be set to other shapes such as a rectangle, a circle, or an ellipse.

[0123] In ACT 32, CPU 311 confirms whether the self-interference signal has been successfully eliminated through secondary control. The specific processing of CPU 311 here can be the same as that illustrated in connection with ACT 28. If the CPU 311 determines that the self-interference signal is successfully eliminated, it returns to ACT 32. In short, if the self-interference signal can be successfully eliminated using the elimination signal generated by the gain and phase shift amount found through the limited range scan, CPU 311 maintains the settings in ACT 31.

[0124] However, there are cases where the self-interference signal cannot be fully eliminated by the elimination signal generated by the secondary control. In addition, there are cases where the self-interference signal fluctuates while the operating state in which the self-interference signal can be effectively eliminated is maintained as described above, and the self-interference signal cannot be fully eliminated. In these cases, CPU 311 determines NO in ACT 32 and proceeds to ACT 33.

[0125] In ACT 33, CPU 311 checks whether the cancellation of the self-interference signal is unsatisfactory. The specific processing performed by CPU 311 here can be the same as the processing illustrated in connection with ACT 29. If the cancellation is not unsatisfactory and the CPU 311 determines NO, the process returns to ACT 30. In short, CPU 311 re-performs secondary control when the cancellation is neither unsatisfactory nor unsatisfactory.

[0126] Furthermore, if the accuracy of the prediction model or the accuracy of the prediction model selection is low, it is also possible to eliminate the situation where the state is neither good nor bad even if the secondary control is repeated multiple times using the gain and phase shift amounts within the limited range RAA determined based on the gain and phase shift amounts indicated by the selected prediction model. Therefore, if such a dangerous situation occurs, CPU 311 may return to ACT 21 if a NO determination is made in ACT 33 after repeating the secondary control a predetermined number of times.

[0127] If the elimination is a failure and the CPU 311 determines YES in ACT 33 , the process proceeds to ACT 34 .

[0128] As ACT 34, the CPU 311 performs sampling and recording of the error level. The specific processing of the CPU 311 here may be the same as the processing illustrated in relation to ACT 24, for example.

[0129] As ACT 35, the CPU 311 selects a prediction model based on the variation pattern of the error level recorded in ACT 34. The specific processing of the CPU 311 here may be the same as the processing exemplified in relation to ACT 25, for example.

[0130] However, if, for example, the fourth threshold is greater than the first threshold, the time lag between the start of sampling and recording after the self-interference signal changes may be greater than the sampling and recording in ACT 24. Therefore, CPU 311 may shorten the time for sampling and recording in ACT 34 compared to the sampling and recording in ACT 24. Furthermore, when selecting a prediction model in ACT 35, CPU 311 may not refer to the initial portion of the variation pattern represented by the prediction model.

[0131] In short, if the cancellation signal generated by the secondary control fails to cancel the self-interference signal, the CPU 311 reselects the prediction model and then returns to ACT 26 to re-perform the primary control based on the reselected prediction model.

[0132] The reader 100 described above generates a prediction model through learning that takes into account actual fluctuations in the self-interference signal. When a significant fluctuation in the self-interference signal occurs, the prediction model is selected based on the initial fluctuation pattern of the fluctuation. A cancellation signal is generated through a primary control using the gain and phase shift values ​​indicated by the prediction model. This eliminates the need for scanning the gain and phase shift values, shortening the time required for setting up the cancellation signal.

[0133] Furthermore, if the cancellation signal generated by primary control fails to effectively cancel the self-interference signal, the reader 100 uses secondary control to adjust the gain and phase shift amount. This effectively cancels the self-interference signal. Furthermore, since the scanning involved in secondary control is performed within a limited range, the time required for this scanning can be shortened compared to a full-range scan.

[0134] Furthermore, if the cancellation signal generated by the secondary control fails to adequately cancel the self-interference signal, the reader 100 re-adjusts the gain and phase shift amount through the secondary control. Therefore, even when the self-interference signal undergoes minor fluctuations, the gain and phase shift amount can be adjusted quickly to compensate for these fluctuations.

[0135] This embodiment can be implemented in various modifications as follows.

[0136] It may be realized as a communication device that communicates with the RFID tag 200 in order to write on the RFID tag 200. It may also be realized as a communication device that communicates with a communication device different from the RFID tag 200.

[0137] Part or all of the functions implemented by the information processing CPU 311 can be implemented by hardware that performs information processing not based on programs, such as logic circuits, etc. In addition, each of the above functions can also be implemented by combining software control with the hardware such as the above logic circuits.

[0138] Although several embodiments of the present invention have been described, these embodiments are provided as examples and are not intended to limit the scope of the invention. These novel embodiments may be implemented in various other forms, and various omissions, substitutions, and modifications may be made without departing from the spirit of the invention. Furthermore, these embodiments and their variations are intended to be included within the scope of the invention and, moreover, within the scope of the invention set forth in the claims and their equivalents.

Claims

1. A communication device, characterized in that: include: a first generating unit, generating a transmission signal for wireless transmission; a common unit that inputs the transmission signal generated by the first generating unit from the input terminal and outputs it from the input / output terminal, and outputs the signal input from the input / output terminal from the output terminal; a second generating unit configured to change the amplitude and phase of the transmission signal generated by the first generating unit to generate a cancellation signal; a synthesis unit for synthesizing the cancellation signal into the signal output from the output terminal; a detection unit configured to detect an error level between the cancellation signal and a self-interference signal included in the output signal from the output terminal; a first control unit configured to control the second generation unit to generate the cancellation signal using a gain and a phase shift amount determined in accordance with the error level detected by the detection unit; a third generating unit recording a plurality of error level variation patterns detected by the detecting unit during a predetermined first period after the error level detected by the detecting unit begins to vary, and generating a plurality of prediction models that associate error level variation patterns predicted for a second period with the gain and phase shift amounts after the variation converges, based on the gain and phase shift amounts determined by the first control unit after the variation converges during the plurality of error level variations and the recorded plurality of variation patterns, wherein the variation convergence means that the amount of change in the error level per unit time becomes smaller than a predetermined threshold value, and the second period is a predetermined period of the first period from the start of the error level variation that is shorter than the first period; a selection unit that selects one of a plurality of prediction models generated by the third generation unit based on a variation pattern detected by the detection unit during the second period after the error level detected by the detection unit starts to vary; and The second control unit controls the second generation unit to generate the cancellation signal using the gain and phase shift amount represented by the prediction model selected by the selection unit.

2. The communication device according to claim 1, wherein The second control unit controls the second generation unit so as to change the gain and the phase shift amount within a limited range that is a part of an adjustable range of the gain and the phase shift amount in the second generation unit, and generates the cancellation signal using the gain and the phase determined based on the error levels respectively detected by the detection unit.

3. The communication device according to claim 2, wherein: The second control unit controls the second generating unit so that when the error level detected by the detection unit deviates from the first range with respect to the elimination signal generated by the second generating unit using the gain and phase shift amount represented by the prediction model selected by the selection unit, the elimination signal is generated using the gain and phase determined based on the error levels respectively detected by the detection unit while the gain and phase shift amount are changed within the limited range. The communication device according to claim 3 , wherein: The second control unit controls the second generation unit so that when the error level detected by the detection unit deviates from the first range with respect to the elimination signal generated by the second generation unit, the elimination signal is generated using the gain and phase determined based on the error levels respectively detected by the detection unit while the gain and phase shift amount are changed within the limited range.

5. The communication device according to any one of claims 1 to 4, wherein: Also includes: The detection unit performs carrier quadrature detection on the synthesized output of the synthesizer and outputs two-channel received baseband signals. The detection unit detects an error level based on the signal levels of the two-channel reception baseband signals output from the detection unit. The communication device according to claim 1 , wherein: The second generating unit includes a variable attenuator that attenuates a transmission signal by a gain corresponding to a gain setting signal, and a variable phase shifter that changes a phase of the transmission signal attenuated by the variable attenuator by a phase shift amount corresponding to a phase shift amount setting signal.

7. The communication device according to claim 1, wherein The first control unit controls the second generation unit so that the gain and phase shift amount vary within the full range of the adjustable range of the gain and phase shift amount in the second generation unit, and generates the cancellation signal using the gain and phase shift amount that minimize the error level detected by the detection unit.

8. The communication device according to claim 1, wherein The third generating unit obtains the error level at a predetermined time interval, and can determine the error levels to be acquired and saved in sequence. When the amount of change corresponding to each unit time of the error level is smaller than a predetermined threshold value, it is determined that the change has converged, and the gain and phase shift amount are changed within the full range of the adjustable range of the gain and phase shift amount. The gain and phase shift amount with the minimum error level are determined, the saved error level and the determined gain and phase shift amount are associated and the change graph is saved, and multiple change graphs are accumulated until the number of saved change graphs reaches the predetermined number. When the number of accumulated change graphs reaches the predetermined number, multiple prediction models are generated.

9. The communication device according to claim 1, wherein The third generating unit generates a plurality of prediction models by associating representative gains and phase shift amounts of the accumulated plurality of variation patterns.

10. The communication device according to claim 1, wherein The third generation unit generates a plurality of prediction models based on similar variation patterns among the accumulated plurality of variation patterns.

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