Receiving device and receiving method

Abstract

The present invention provides a receiving device and a receiving method capable of achieving desired performance. [Solution] The receiving device 10 comprises a receiving unit 11 and an adaptive equivalence processing unit 12. The receiving unit 11 generates a received signal based on a first radio signal received by a first antenna and a second radio signal received by a second antenna. The adaptive equivalence processing unit 12 performs adaptive equivalence processing to asymptotically approach a predetermined training signal the received signal generated by the receiving unit 11 based on the first radio signal and the second radio signal.

Description

Technical Field

[0001] The present invention relates to a receiving apparatus and a receiving method, and can be suitably used for, for example, a receiving apparatus and a receiving method that receive a radio signal by a first antenna and a second antenna.

Background Art

[0002] For example, Patent Documents 1 and 2 are known as technologies for performing diversity reception using a first antenna and a second antenna. Patent Documents 1 and 2 describe switching the antenna to be received based on the reception quality of the radio signal.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in related technologies such as Patent Documents 1 and 2, it may be difficult to obtain desired performance.

[0005] Other problems and novel features will become apparent from the description of this specification and the accompanying drawings.

Means for Solving the Problems

[0006] According to one embodiment, the receiving apparatus generates a received signal based on a first radio signal received by a first antenna and a second radio signal received by a second antenna. The receiving apparatus performs an adaptive equivalent process of making the generated received signal asymptotic to a predetermined training signal.

Effects of the Invention

[0007] According to the above embodiment, the desired performance can be obtained. [Brief explanation of the drawing]

[0008] [Figure 1] This is a timing chart showing the operation during antenna switching in Example 1. [Figure 2] This is a diagram showing the configuration of the analog front-end in Example 2. [Figure 3] This is a configuration diagram showing the general configuration of the receiving device according to the embodiment. [Figure 4] This is a configuration diagram showing an example of the configuration of a receiving device according to Embodiment 1. [Figure 5] This is a diagram showing an example configuration of an adaptive equivalent circuit according to Embodiment 1. [Figure 6] This flowchart shows an example of the operation of the receiving device according to Embodiment 1. [Figure 7] This is a configuration diagram showing an example of the configuration of a receiving device according to Embodiment 2. [Figure 8] This is a diagram showing an example configuration of an adaptive equivalent circuit according to Embodiment 2. [Figure 9] This flowchart shows an example of the operation of the receiving device according to Embodiment 2. [Figure 10] This graph shows a specific example of a signal to illustrate an example of the operation of the receiving device according to Embodiment 2. [Figure 11] This is a configuration diagram showing an example of the configuration of a receiving device according to Embodiment 3. [Figure 12] This flowchart shows an example of the operation of the receiving device according to Embodiment 3. [Modes for carrying out the invention]

[0009] Hereinafter, embodiments will be described with reference to the drawings. For the sake of clarity of explanation, the following description and drawings are appropriately omitted and simplified. Also, in each drawing, the same elements are denoted by the same reference numerals, and duplicate explanations are omitted as necessary.

[0010] (Examination Example) First, Examination Examples 1 and 2 studied by the inventor will be described.

[0011] Examination Example 1 is an example in which, similar to Patent Documents 1 and 2, diversity reception is performed by switching two antennas. In Examination Example 1, the antennas for receiving from the two antennas are switched by a switch circuit. Further, the consistency (correlation) between the received signal and a predetermined training signal (also called a preamble signal) is detected, and the antenna to be used is determined.

[0012] FIG. 1 shows the operation at the time of antenna switching in Examination Example 1. As shown in FIG. 1, in Examination Example 1, during the correlation detection period, the antennas for receiving the signal (training signal) are switched to monitor the levels of both antennas, and the antenna to be used is determined based on the detected correlation value.

[0013] In Examination Example 1, at least three times (three monitoring times) of antenna switching time are required until the antenna to be used is determined. That is, first, the first antenna is selected, and the correlation between the signal received by the first antenna and the training signal is detected. Next, the antenna is switched to the second antenna, and the correlation between the signal received by the second antenna and the training signal is detected. At this time, the reception quality of the first antenna may vary. Therefore, the antenna is switched back to the first antenna, and the correlation between the signal received by the first antenna and the training signal is detected again, and finally the antenna with the higher correlation is selected.

[0014] Therefore, in Study Example 1, it takes time to determine the optimal antenna. Also, in Study Example 1, when the signal-to-noise ratio (SNR) deteriorates, the signal is buried in noise, so it is necessary to continuously add for a long time to cancel the noise, and correlation detection takes time. Note that when noise is added for one cycle, it is canceled out, and the signal becomes larger, so the SNR is improved.

[0015] Study Example 2 is an example in which diversity reception is performed using the maximum ratio combining (MRC) method. In the maximum ratio combining method, after phase adjustment so that the phases of the signals received by two antennas are the same phase, the two signals are combined so that the SNR is maximized.

[0016] FIG. 2 shows the configuration of the analog front end in Study Example 2. As shown in FIG. 2, the analog front end 90 of Study Example 2 includes phase shifters 91 and 92, variable gain amplifiers 93 and 94, and a combiner 95 in order to perform combination by the maximum ratio combining method. The combiner 95 combines the signal received by the antenna 81 and the signal received by the antenna 82. Specifically, it combines the signal whose phase and gain are adjusted by the phase shifter 91 and the variable gain amplifier 93 and the signal whose phase and gain are adjusted by the phase shifter 92 and the variable gain amplifier 94.

[0017] In Study Example 2, since the signals received by two antennas are mixed in the analog front end, a switch for switching the antennas is unnecessary. However, in Study Example 2, although the antenna switching time is unnecessary compared to Study Example 1, since reception is not possible unless the phases match, RF circuits for the phase adjustment circuit and the gain adjustment circuit are required for two paths, and the circuit size increases.

[0018] Thus, in Example 1, the antenna with the better signal-to-noise ratio (SNR) is selected by correlation detection using antenna switching. However, Example 1 requires at least three antenna switching cycles, and there is a problem that the detection time becomes too long when the SNR deteriorates. For example, the Wi-Sun standard and other standards specify the time (training period) from the start of signal reception until the antenna is determined and demodulation becomes possible. However, in Example 1, it is difficult to obtain performance that meets the standards, and if the processing time until the antenna is determined to meet the Wi-Sun standard or other standards is reduced, the detection accuracy decreases, resulting in performance degradation such as deterioration of reception sensitivity and incorrect antenna selection.

[0019] In Example 2, the signals are mixed at the analog front end using the maximum ratio combining method. In Example 2, a switch to change the antenna is not required, and processing time is faster, but a challenge arises in that two RF circuits are needed for the phase adjustment circuit and the gain adjustment circuit, which increases the circuit size.

[0020] Therefore, in this embodiment, the maximum ratio combining method, which combines the signals from two antennas without switching antennas, is combined with adaptive equivalent processing on the digital side. This eliminates the antenna selection time that was required for three antenna switches in Example 1, thereby shortening the processing time (to about 1 / 3). Furthermore, by performing adaptive equivalent processing on the digital side, diversity reception becomes possible without adding any analog front-end circuitry.

[0021] (Summary of the embodiment) Figure 3 shows an overview of the receiving device 10 according to the embodiment. The receiving device 10 is a receiving device that receives wireless signals in a wireless communication system. The receiving device 10, together with a transmitting device that transmits wireless signals, constitutes a wireless communication system. The receiving device 10 mainly has the function of receiving wireless signals, but it may also be a communication device that has the function of transmitting wireless signals. The receiving device 10 may receive wireless signals of any wireless communication standard. For example, the wireless communication standard may be Wi-Sun, wireless LAN, Bluetooth®, mobile communication standards such as 4G and 5G, or other standards. In wireless communication standards, when a transmitting device starts transmitting data, it is stipulated that it first transmits a predetermined training signal for a predetermined period (training period) and then transmits a signal containing data. The receiving device 10 receives a wireless signal containing the training signal.

[0022] As shown in Figure 3, the receiving device 10 comprises a receiving unit 11 and an adaptive equivalent processing unit 12. For example, the receiving unit 11 and the adaptive equivalent processing unit 12 may be composed of one or any number of semiconductor devices. For example, the receiving unit 11 may be composed of an analog circuit and the adaptive equivalent processing unit 12 may be composed of a digital circuit, or the receiving unit 11 and the adaptive equivalent processing unit 12 may be composed of digital circuits.

[0023] The receiving device 10 performs diversity reception, for example, using a first antenna and a second antenna. The receiving unit 11 generates a received signal based on a first radio signal received by the first antenna and a second radio signal received by the second antenna. For example, the receiving unit 11 may include a combining unit that combines the first radio signal and the second radio signal to generate a combined received signal.

[0024] Furthermore, the receiving unit 11 may include a first receiving unit that generates a first received signal based on a first radio signal, and a second receiving unit that generates a second received signal based on a second radio signal.

[0025] The adaptive equivalence processing unit 12 performs adaptive equivalence processing to asymptotically bring the received signal generated by the receiving unit 11 closer to a predetermined training signal. When the receiving unit 11 combines a first radio signal and a second radio signal, the adaptive equivalence processing unit 12 may perform adaptive equivalence processing on the combined received signal. For example, the adaptive equivalence processing unit 12 may include a phase difference calculation unit that calculates the phase difference between the received signal after adaptive equivalence processing and a predetermined training signal. In this case, the receiving unit 11 may include a phase adjustment unit that adjusts the phase difference between the first radio signal and the second radio signal based on the calculated phase difference.

[0026] As described above, the receiving unit 11 may generate a first received signal based on a first radio signal and a second received signal based on a second radio signal. In this case, the adaptive equivalent processing unit 12 may include a first adaptive equivalent processing unit and a second adaptive equivalent processing unit. The first adaptive equivalent processing unit performs a first adaptive equivalent processing to asymptotically approach a predetermined training signal with the generated first received signal. The second adaptive equivalent processing unit performs a second adaptive equivalent processing to asymptotically approach a predetermined training signal with the generated second received signal. For example, the adaptive equivalent processing unit 12 may include a combining unit that combines the first received signal after the first adaptive equivalent processing and the second received signal after the second adaptive equivalent processing. The adaptive equivalent processing unit 12 may also include a phase adjustment unit that adjusts the phase difference between the first received signal after the first adaptive equivalent processing and the second received signal after the second adaptive equivalent processing.

[0027] In this embodiment, the receiving device performing diversity reception performs adaptive equivalence processing on the signal based on the wireless signals received by the two antennas, causing it to asymptotically approach the training signal. This eliminates the need for antenna switching, thus shortening the processing time. As a result, the necessary processing can be completed within the training period specified in the standard, and the desired performance can be obtained. Furthermore, by performing adaptive equivalence processing, implementation using digital circuits becomes possible, thus suppressing an increase in circuit size.

[0028] (Embodiment 1) Next, Embodiment 1 will be described. In this embodiment, an example will be described in which the signals from two antennas are combined at the analog front end, and adaptive equivalence processing is performed on the combined signal.

[0029] Figure 4 shows an example configuration of the receiving device 100 according to this embodiment. In the example in Figure 4, the receiving device 100 includes antennas 101-1 and 101-2, an analog front end 110, an adaptive equivalent circuit 120, an AGC circuit 130, a training signal generation circuit 140, and a demodulation circuit 150. Note that the receiving device 100 is not limited to two antennas, but may have any number of antennas, two or more. That is, adaptive equivalent processing may be performed on signals received by two or more antennas.

[0030] For example, the analog front-end 110 is composed of analog circuits. The adaptive equivalent circuit 120, AGC circuit 130, training signal generation circuit 140, and demodulation circuit 150 are composed of digital circuits. Each part of the receiving device 100 may be implemented using a semiconductor device. The analog front-end 110 may be included in a semiconductor device that implements analog circuits. The adaptive equivalent circuit 120, AGC circuit 130, training signal generation circuit 140, and demodulation circuit 150 may be included in a semiconductor device that implements digital signal processing circuits. For example, the semiconductor device may be a semiconductor package including a first semiconductor chip and a second semiconductor chip. The first semiconductor chip may include the analog front-end 110. The second semiconductor chip may include the adaptive equivalent circuit 120, AGC circuit 130, training signal generation circuit 140, and demodulation circuit 150.

[0031] Antenna 101-1 (first antenna) and antenna 101-2 (second antenna) each receive radio waves. Antennas 101-1 and 101-2 generate radio frequency RF signals RS1 (first radio signal) and RS2 (second radio signal) respectively, according to the received radio waves.

[0032] The analog front-end 110 is a receiving circuit (receiving section) that receives signals via antennas 101-1 and 101-2. The analog front-end 110 combines the RF signals RS1 and RS2 received by antennas 101-1 and 101-2 to generate a combined digital signal CS1. In the example shown in Figure 4, the analog front-end 110 includes a combiner 111, a variable gain amplifier 112, and an ADC 113.

[0033] The combiner 111 is a combining circuit (combining unit) that combines the RF signals RS1 and RS2 received by antennas 101-1 and 101-2 to generate a combined analog signal CS0.

[0034] The variable gain amplifier 112 is a gain adjustment circuit (gain adjustment unit) that adjusts the gain (amplitude) of the combined signal CS0 synthesized by the combiner 111. The variable gain amplifier 112 adjusts the amplitude of the combined signal CS0 to within the input range of the ADC 113 in accordance with the control from the AGC circuit 130. If the amplitude of the combined signal CS0 is within the input range of the ADC 113, the gain adjustment by the variable gain amplifier 112 may be omitted.

[0035] The ADC (Analog-Digital Converter) 113 performs AD conversion on the combined signal CS0, which has been gain-adjusted by the variable gain amplifier 112, to generate a combined digital signal CS1.

[0036] The adaptive equivalent circuit 120 is an adaptive equivalent processing circuit (adaptive equivalent processing unit) that performs adaptive equivalent processing on the composite signal CS1 generated by the analog front-end 110 and generates the output signal OS after adaptive equivalent processing. The adaptive equivalent circuit 120 uses the training signal TS from the training signal generation circuit 140 as a reference to asymptotically approach the composite signal CS1 to the training signal TS and generates the asymptotic output signal OS. The adaptive equivalent circuit 120 performs transmission path estimation by adaptive equivalent processing based on the same training signal TS as the transmitter and adjusts the amplitude and phase of the composite signal CS1, which includes the signals of each antenna. As for the adaptive equivalent processing method, LMS (Least Mean Square), Kalman, etc. may be used.

[0037] The AGC (Automatic Gain Control) circuit 130 automatically controls the gain of the variable gain amplifier 112. For example, the AGC circuit 130 monitors the combined signal CS0 generated by the combiner 111 and controls the gain of the variable gain amplifier 112 so that the amplitude of the combined signal CS0 is within the input range of the ADC 113.

[0038] The training signal generation circuit 140 generates a predetermined training signal TS. The training signal TS is the same signal as the training signal transmitted by the transmitting device, and is a signal with a predetermined pattern defined in the communication standard.

[0039] The demodulation circuit 150 performs demodulation processing on the output signal OS that has undergone adaptive equivalence processing by the adaptive equivalence circuit 120. The demodulation circuit 150 performs demodulation processing in accordance with the modulation scheme of the transmitting device and generates received data. For example, the demodulation circuit 150 demodulates the signal according to the scheme defined by standards such as Wi-Sun or wireless LAN.

[0040] Figure 5 shows an example configuration of the adaptive equivalent circuit 120 in this embodiment. The adaptive equivalent circuit 120 is a circuit that estimates the transmission path from the difference between the input signal and the reference signal and determines the optimal filter through frequency-dependent feedback. In the example in Figure 5, the adaptive equivalent circuit 120 includes an FIR adaptive filter 121, an error calculation unit 122, and an adaptive algorithm unit 123.

[0041] The FIR (Finite Impulse Response) adaptive filter 121 filters the composite signal CS1 with filter characteristics controlled by the adaptive algorithm unit 123. The FIR adaptive filter 121 outputs the filtered output signal OS.

[0042] The error calculation unit 122 calculates the difference between the output signal OS output from the FIR adaptive filter 121 and the training signal TS, and outputs an error signal ES that shows the calculated difference (error). For example, the error signal ES includes the phase difference and amplitude difference of the two signals.

[0043] The adaptive algorithm unit 123 controls the filter characteristics of the FIR adaptive filter 121 based on the error signal ES from the error calculation unit 122, according to a predetermined adaptive algorithm (such as LMS or Kalman). The adaptive algorithm unit 123 adjusts the tap coefficients of the FIR adaptive filter 121 so that the error between the output signal OS and the training signal TS is minimized. By repeatedly performing feedback control to the FIR adaptive filter 121 by the adaptive algorithm unit 123, the output signal OS asymptotically approaches (converges) to the training signal TS. For example, the output signal OS after adaptive equivalence processing is a signal that has asymptotically approached and converged to the training signal TS.

[0044] Figure 6 shows an example of the operation of the receiving device 100 according to this embodiment. In the example in Figure 6, the RF signal RS1 is received by antenna 101-1 (S101), and the RF signal RS2 is received by antenna 101-2 (S102).

[0045] Next, the combiner 111 combines the RF signal RS1 received by antenna 101-1 and the RF signal RS2 received by antenna 101-2 (S103). The variable gain amplifier 112 adjusts the gain of the combined signal CS0 produced by the combiner 111 according to the control from the AGC circuit 130. Subsequently, the ADC 113 performs AD conversion on the combined signal CS0 after the gain adjustment by the variable gain amplifier 112 (S104).

[0046] Next, the adaptive equivalent circuit 120 performs adaptive equivalent processing on the combined signal CS1 of the digital signals converted by the ADC 113 (S105). The adaptive equivalent circuit 120 uses the training signal TS from the training signal generation circuit 140 as a reference to asymptotically approach the combined signal CS1 to the training signal TS and generate the output signal OS. Specifically, the adaptive algorithm unit 123 adjusts the characteristics of the FIR adaptive filter 121 so that the error between the output signal OS and the training signal TS is small.

[0047] Next, the demodulation circuit 150 performs demodulation processing on the output signal OS after adaptive equivalent processing by the adaptive equivalent circuit 120 (S106).

[0048] As described above, in this embodiment, the signals from the two antennas are combined at the analog front end, and adaptive equivalence processing is performed on the combined signal. In this embodiment, since only asymptotic processing by adaptive equivalence is performed compared to the antenna switching method of Study Example 1, problems such as incorrect antenna selection and processing time are avoided. In this embodiment, since the time required for antenna switching is eliminated, the processing time can be reduced to about one-third compared to Study Example 1.

[0049] In the Maximum Ratio Combination (MRC) method in Study Example 2, the RF signals from the two antennas were mixed after adjusting their phase and amplitude using an analog circuit. In this embodiment, compared to Study Example 2, an increase in circuit area can be prevented by using an adaptive equivalent circuit of the digital circuit.

[0050] (Embodiment 2) Next, Embodiment 2 will be described.

[0051] As described above, in Embodiment 1, the signals from the two antennas are combined at the analog front end, and adaptive equivalent processing is performed on the combined signal. In this case, if the phase of the signals between the antennas is shifted by 180 degrees, the phase difference cannot be properly adjusted, which may lead to a decrease in the signal-to-noise ratio. Therefore, in this embodiment, the phase difference is detected by an adaptive equivalent circuit for the receiving device configuration in Embodiment 1, and the phase difference of the signals between the antennas is adjusted.

[0052] Figure 7 shows an example configuration of the receiving device 100 according to this embodiment. In the example in Figure 7, the receiving device 100 has the same configuration as in Figure 4. That is, the receiving device 100 includes antennas 101-1 and 101-2, an analog front end 110, an adaptive equivalent circuit 120, an AGC circuit 130, a training signal generation circuit 140, and a demodulation circuit 150. Here, we will mainly describe the configuration that differs from that in Figure 4.

[0053] In this embodiment, the adaptive equivalent circuit 120 outputs phase shift information PS, which indicates the phase difference between the output signal OS after adaptive equivalent processing and the training signal TS, to the combiner 111 of the analog front end 110.

[0054] The combiner 111 adjusts the phase difference between the RF signal RS1 received by antenna 101-1 and the RF signal RS2 received by antenna 101-2 based on the phase shift information PS from the adaptive equivalent circuit 120. For example, the combiner 111 includes a phase adjustment circuit (phase adjustment unit) that adjusts the phase difference. The phase adjustment circuit is, for example, a phase shifter. The phase adjustment circuit may be placed between antennas 101-1 and 101-2 and the combiner 111. The combiner 111 combines the RF signals RS1 and RS2, whose phases have been adjusted based on the phase shift information PS.

[0055] Figure 8 shows an example configuration of the adaptive equivalent circuit 120 according to this embodiment. In the example in Figure 8, the adaptive equivalent circuit 120 includes an FIR adaptive filter 121, an error calculation unit 122, an adaptive algorithm unit 123, and a phase difference calculation unit 124, similar to Figure 5.

[0056] The phase difference calculation unit 124 calculates the phase difference between the output signal OS, which is output from the FIR adaptive filter 121 after adaptive equivalence processing, and the training signal TS. The phase difference can be obtained by multiplying the output signal OS and the training signal TS. The phase difference calculation unit 124 outputs phase shift information PS, based on the calculated phase difference, to the combiner 111.

[0057] In this embodiment, in order to determine the phase difference between the two antennas, the phase difference is calculated twice by the error calculation unit 122: once in the direction where the difference is maximized and once in the direction where it is minimized. The difference between these two phase differences becomes the phase difference between the signals between the antennas. Specifically, the phase difference calculation unit 124 calculates a first phase difference between the output signal OS and the training signal TS when the error calculated by the error calculation unit 122 is asymptotically approached (converged) in the direction where the error calculated by the error calculation unit 122 is minimized. The phase difference calculation unit 124 then calculates a second phase difference between the output signal OS and the training signal TS when the error calculated by the error calculation unit 122 is minimized. Furthermore, the phase difference calculation unit 124 calculates the difference between the first phase difference when the error is maximized and the second phase difference when the error is minimized, and outputs phase shift information PS indicating the calculated difference.

[0058] For example, suppose the phase difference of the signal from antenna 101-1 is -10 degrees and the phase difference of the signal from antenna 101-2 is +15 degrees. In this case, if the phase of antenna 101-2 is shifted by -15 degrees, the phases of antennas 101-1 and 101-2 will become the same. Therefore, -15 degrees is fed back to the analog front end 110 as phase shift information PS.

[0059] The basic operation of the receiving device 100 according to this embodiment is the same as in Figure 6 of Embodiment 1. In this embodiment, as shown in Figure 6, phase shift information is fed back from adaptive equivalence processing (S105) for RF signal synthesis (S103).

[0060] Using Figures 9 and 10, the operation of calculating the phase difference in the adaptive equivalent circuit 120 and feeding back the phase shift information will be explained. Note that in Figure 9, S203 and S204 may be performed before S201 and S202.

[0061] As shown in Figure 9, the adaptive equivalent circuit 120 performs an asymptotic process (adaptive equivalent process) that maximizes the error (S201). For example, the phase difference calculation unit 124 may switch the operation (direction of asymptosis) of the adaptive algorithm unit 123 in order to calculate the phase difference between the two antennas. The adaptive algorithm unit 123 performs an adaptive equivalent process that asymptotically approaches in the opposite direction to that of Embodiment 1. Specifically, it adjusts the characteristics of the FIR adaptive filter 121 so that the error (error signal ES) between the output signal OS that has passed through the FIR adaptive filter 121 and the training signal TS is maximized.

[0062] Next, the adaptive equivalent circuit 120 calculates the phase difference between the asymptotic result with the maximum error (the result asymptotically approaching the direction with a higher signal-to-noise ratio) and the training signal (S202). The phase difference calculation unit 124 calculates the phase difference between the output signal OS and the training signal TS when the error between the output signal OS and the training signal TS, which have passed through the FIR adaptive filter 121, is asymptotically approached to maximize the error. For example, in the example in Figure 10, the phase difference d1 (first phase difference) between the output signal OSa, which has been asymptotically approached to maximize the error, and the training signal TS is calculated.

[0063] Next, the adaptive equivalent circuit 120 performs asymptotic processing to minimize the error (S203). The adaptive algorithm unit 123 performs adaptive equivalent processing that asymptotically approaches in the same direction as in Embodiment 1. Specifically, it adjusts the characteristics of the FIR adaptive filter 121 so that the error (error signal ES) between the output signal OS that has passed through the FIR adaptive filter 121 and the training signal TS is minimized.

[0064] Next, the adaptive equivalent circuit 120 calculates the phase difference between the asymptotic result with the minimum error (the result asymptotically approaching a lower signal-to-noise ratio) and the training signal (S204). The phase difference calculation unit 124 calculates the phase difference between the output signal OS and the training signal TS when the error between the output signal OS and the training signal TS, which have passed through the FIR adaptive filter 121, is asymptotically minimized (converged). For example, in the example in Figure 10, the phase difference d2 (second phase difference) between the output signal OSb, which has been asymptotically approached to minimize the error, and the training signal TS is calculated.

[0065] Next, the adaptive equivalent circuit 120 calculates the difference between the two phase differences (S205). The phase difference calculation unit 124 calculates the difference between the phase difference when the error is at its maximum, calculated in S202, and the phase difference when the error is at its minimum, calculated in S204, as the phase difference between the two antennas. In the example in Figure 10, the difference between the phase difference d1 between the output signal OSa and the training signal TS, and the phase difference d2 between the output signal OSb and the training signal TS is calculated.

[0066] Next, the adaptive equivalent circuit 120 feeds back the difference between the two phase differences as phase shift information PS to the analog front end 110 (S206). Based on the fed-back phase shift information PS, the combiner 111 adjusts the phase difference between the RF signal RS1 received by antenna 101-1 and the RF signal RS2 received by antenna 101-2. The combiner 111 may adjust the phase of either the RF signal RS1 or the RF signal RS2. For example, the phase of the RF signal with the lower signal-to-noise ratio (signal OSa in Figure 10) may be adjusted to match the phase of the RF signal with the higher signal-to-noise ratio (signal OSb in Figure 10). Based on the phase shift information PS, the combiner 111 shifts the phase of either the RF signal RS1 or the RF signal RS2 and combines the shifted RF signals RS1 and RS2.

[0067] As described above, in this embodiment, the phase difference between the signals is adjusted by detecting the phase difference in the adaptive equivalent circuit and feeding it back to the analog front end. This prevents a decrease in the signal-to-noise ratio (SNR) when the phase of the signals between the antennas is shifted by 180 degrees. Since the adaptive equivalent circuit can determine the optimal antenna signal and the phase difference between the antennas, it is possible to provide feedback to adjust the phase to the optimal antenna signal. The SNR can be improved by matching the phase of the signal from the antenna with the lower SNR to the phase of the signal from the antenna with the higher SNR.

[0068] (Embodiment 3) Next, Embodiment 3 will be described. In this embodiment, an example will be described in which adaptive equivalence processing is performed on each of the received signals from the two antennas, and the phase difference of the signals after adaptive equivalence processing is corrected and the signals are mixed.

[0069] Figure 11 shows an example configuration of the receiving device 100 according to this embodiment. In the example in Figure 11, the receiving device 100 includes antennas 101-1 and 101-2, ADCs 201-1 and 201-2, DCOs 202-1 and 202-2, and sine wave oscillators 203-1 and 203-2. Furthermore, the receiving device 100 includes adaptive equivalent circuits 120-1 and 120-2, a training signal generation circuit 140, a delay circuit 204, a combiner 205, and a demodulation circuit 150.

[0070] For example, components other than antennas 101-1 and 101-2 are implemented by digital circuits. The digital circuits include DCOs 202-1 and 202-2, and sine wave oscillators 203-1 and 203-2. Furthermore, the digital circuits include adaptive equivalent circuits 120-1 and 120-2, a training signal generation circuit 140, a delay circuit 204, a combiner 205, and a demodulation circuit 150.

[0071] Antenna 101-1 (first antenna) and antenna 101-2 (second antenna) each receive radio waves in the same manner as in Figure 4. Antennas 101-1 and 101-2 generate high-frequency RF signals RS1 (first radio signal) and RS2 (second radio signal) respectively, according to the received radio waves.

[0072] For example, ADC201-1 and DCO202-1 constitute a first receiving circuit (first receiving unit) that receives the RF signal RS1 from antenna 101-1. ADC201-2 and DCO202-2 constitute a second receiving circuit (second receiving unit) that receives the RF signal RS2 from antenna 101-2.

[0073] ADC201-1 (first AD converter) and ADC201-2 (second AD converter) perform AD conversion on the RF signals RS1 and RS2 received by antennas 101-1 and 101-2, respectively. ADC201-1 and ADC201-2 generate the RF signals RS1 and RS2 of the AD-converted digital signals. In this example, since the RF signals are directly AD-converted, a gain adjustment circuit like that in Embodiment 1 is not required.

[0074] The DCO (Digitally Controlled Oscillator) 202-1 (first frequency converter) and DCO202-2 (second frequency converter) receive digital RF signals RS1 and RS2 as input. DCO202-1 and DCO202-2 also receive sine waves generated by sine wave oscillators 203-1 and 203-2 as input. Based on the sine waves generated by sine wave oscillators 203-1 and 203-2, DCO202-1 and 202-2 generate IF signals IS1 and IS2 with frequencies corresponding to the RF signals RS1 and RS2, respectively. IF signals IS1 and IS2 are intermediate frequency digital sine wave signals. DCO202-1 and DCO202-2 are frequency converters (frequency conversion units) that convert high-frequency RF signals RS1 and RS2 to intermediate frequency IF signals IS1 and IS2.

[0075] The adaptive equivalent circuit 120-1 (first adaptive equivalent processing unit) performs adaptive equivalent processing (first adaptive equivalent processing) on ​​IS1 generated by DCO202-1 based on the training signal TS, similar to Figures 4 and 5. The adaptive equivalent circuit 120-1 generates the output signal OS1 after adaptive equivalent processing. Similarly, the adaptive equivalent circuit 120-2 (second adaptive equivalent processing unit) performs adaptive equivalent processing (second adaptive equivalent processing) on ​​IS2 generated by DCO202-2 based on the training signal TS. The adaptive equivalent circuit 120-2 generates the output signal OS2 after adaptive equivalent processing. The adaptive equivalent circuit 120-1 also includes a phase difference calculation unit 124 (first phase difference calculation unit) that calculates the phase difference between the output signal OS1 after adaptive equivalent processing and the training signal TS, similar to Figure 8. The adaptive equivalent circuit 120-1 outputs phase shift information PS1 based on the calculated phase difference to the delay circuit 204. Similarly, the adaptive equivalent circuit 120-2 includes a phase difference calculation unit 124 (second phase difference calculation unit) that calculates the phase difference between the output signal OS2 after adaptive equivalent processing and the training signal TS. The adaptive equivalent circuit 120-2 outputs phase shift information PS2 based on the calculated phase difference to the delay circuit 204.

[0076] The delay circuit 204 delays the output signal OS2 generated by the adaptive equivalent circuit 120-2 based on the difference between the phase shift information PS1 from the adaptive equivalent circuit 120-1 and the phase shift information PS2 from the adaptive equivalent circuit 120-1. The phase shift information PS1 indicates the phase difference between the output signal OS1 and the training signal TS. The phase shift information PS2 indicates the phase difference between the output signal OS2 and the training signal TS. The delay circuit 204 generates the delayed output signal OS2'. The delay circuit 204 is a phase adjustment circuit (phase adjustment unit) that adjusts the phase difference between the output signal OS1 and the output signal OS2 by adjusting the delay amount of the output signal OS2. The delay circuit 204 may also delay the output signal OS1 generated by the adaptive equivalent circuit 120-1.

[0077] The combiner 205 combines the output signal OS1 from the adaptive equivalent circuit 120-1 after adaptive equivalent processing and the output signal OS2' from the delay circuit 204 after phase adjustment, and outputs the combined signal as the output signal OS. The training signal generation circuit 140 and the demodulation circuit 150 are the same as in Figure 4.

[0078] Figure 12 shows an example of the operation of the receiving device 100 according to this embodiment. In Figure 12, the processing of the received signal from antenna 101-1 in S301-1 to S305-1 and the processing of the received signal from antenna 101-2 in S301-2 to S305-2 are performed in parallel and simultaneously.

[0079] In the processing of the signal received by antenna 101-1 from S301-1 to S305-1, first, the RF signal RS1 is received by antenna 101-1 (S301-1). Next, ADC201-1 performs AD conversion on the RF signal RS1 received by antenna 101-1 to generate a digital RF signal RS1 (S302-1). Subsequently, DCO202-1 converts the digital RF signal RS1 converted by ADC201-1 into an intermediate frequency IF signal IS1 (S303-1).

[0080] Next, the adaptive equivalent circuit 120-1 performs adaptive equivalent processing on the IF signal IS1 converted by DCO202-1 based on the training signal TS from the training signal generation circuit 140 (S304-1). Similar to Embodiment 1, the adaptive equivalent circuit 120-1 performs adaptive equivalent processing so as to minimize the error between the training signal TS and the output signal OS1. The adaptive equivalent circuit 120-1 outputs the output signal OS1 after adaptive equivalent processing. Next, the adaptive equivalent circuit 120-1 calculates the phase difference (phase shift information PS1) between the output signal OS1 after adaptive equivalent processing and the training signal TS (S305-1).

[0081] Similarly, in the processing of the received signal from antenna 101-2 in S301-2 to S305-2, antenna 101-2 receives the RF signal RS2 (S301-2). Subsequently, ADC201-2 performs AD conversion on the RF signal RS2 received by antenna 101-2 to generate a digital RF signal RS2 (S302-2). Subsequently, DCO202-2 converts the digital RF signal RS2 converted by ADC201-2 into an intermediate frequency IF signal IS2 (S303-2).

[0082] Next, the adaptive equivalent circuit 120-2 performs adaptive equivalent processing on the IF signal IS2 converted by DCO202-2 based on the training signal TS from the training signal generation circuit 140 (S304-2). Similar to Embodiment 1, the adaptive equivalent circuit 120-2 performs adaptive equivalent processing so as to minimize the error between the training signal TS and the output signal OS2. The adaptive equivalent circuit 120-2 outputs the output signal OS2 after adaptive equivalent processing. Next, the adaptive equivalent circuit 120-2 calculates the phase difference (phase shift information PS2) between the output signal OS2 after adaptive equivalent processing and the training signal TS (S305-2).

[0083] Next, the delay circuit 204 adjusts the phase of the output signal OS2 based on the difference between the phase difference indicated by the phase shift information PS1 and the phase difference indicated by the phase shift information PS2 (S306). The phase shift information PS1 indicates the phase difference between the output signal OS1 after adaptive equivalent processing by the adaptive equivalent circuit 120-1 and the training signal TS. The phase shift information PS2 indicates the phase difference between the output signal OS2 after adaptive equivalent processing by the adaptive equivalent circuit 120-2 and the training signal TS. The delay circuit 204 calculates the difference between the phase shift information PS1 and the phase shift information PS2, delays the output signal OS2 to adjust its phase based on the calculated difference, and outputs the phase-adjusted output signal OS2'.

[0084] Next, the combiner 205 combines the output signal OS1 from the adaptive equivalent circuit 120-1 after adaptive equivalent processing with the output signal OS2' from the delay circuit 204 after phase adjustment (S307). The combiner 205 outputs the combined signal as the output signal OS. Subsequently, the demodulation circuit 150 performs demodulation processing on the output signal OS (S308).

[0085] As described above, in this embodiment, adaptive equivalence processing is performed on each of the received signals from the two antennas. Since the phase difference between the received signal and the training signal of each antenna can be calculated during each adaptive equivalence processing, the phase difference between the two antennas is corrected, and the phases are aligned and mixed. Even in this case, antenna switching is unnecessary, thus preventing problems such as incorrect antenna selection and processing time issues.

[0086] Furthermore, in this embodiment, since each circuit of the receiving device can be made of digital circuits, an increase in circuit area can be prevented. For example, by directly performing AD conversion of the RF signal, the VCO (Voltage Controlled Oscillator), which is an RF circuit, can be replaced with a DCO (Digital Oscillator), thereby reducing the circuit area.

[0087] Furthermore, each element described and explained in the drawings as a functional block that performs various processes can be composed of a CPU (Central Processing Unit), memory, and other circuits in hardware terms. In software terms, it is implemented by programs loaded into memory. Therefore, it will be understood by those skilled in the art that these functional blocks can be implemented in various ways using hardware alone, software alone, or a combination thereof, and are not limited to any one of these.

[0088] The above program can be stored and supplied to a computer using various types of non-transitory computer-readable medium. Non-transitory computer-readable medium includes various types of tangible storage medium. Examples of non-transitory computer-readable medium include magnetic storage media (e.g., flexible disks, magnetic tapes, hard disk drives), magneto-optical storage media (e.g., magneto-optical disks), CD-ROMs (Read Only Memory), CD-Rs, and CD-R / Ws. Examples of non-transitory computer-readable medium include semiconductor memory (e.g., mask ROMs, PROMs (Programmable ROMs), EPROMs (Erasable PROMs), flash ROMs, and RAMs (Random Access Memory)). The program may also be supplied to the computer using various types of transient computer-readable medium. Examples of transient computer-readable medium include electrical signals, optical signals, and electromagnetic waves. Temporary computer-readable media can supply programs to a computer via wired communication channels such as electric wires and optical fibers, or via wireless communication channels.

[0089] The present invention has been described in detail above based on embodiments. However, it goes without saying that the present invention is not limited to the embodiments already described, and various modifications are possible without departing from the spirit of the invention. [Explanation of symbols]

[0090] 10 Receiving device 11 Receiving unit 12 Adaptive Equivalence Processing Unit 81, 82 Antennas 90 Analog Front End 91, 92 Phase Shifter 93, 94 Variable Gain Amplifier 95 Combiner 100 Receiver 101-1, 101-2 Antennas 110 Analog Front End 111 Combiner 112 Variable Gain Amplifier 113 ADC Adaptive equivalent circuits for 120, 120-1, and 120-2. 121 FIR adaptive filter 122 Error calculation section 123 Adaptive Algorithm Section 124 Phase difference calculation section 130 AGC circuit 140 Training signal generation circuit 150 Demodulation Circuit 201-1, 201-2 ADC 202-1, 202-2 DCO 203-1, 203-2 Sine wave oscillator 204 Delay Circuit 205 Combiner

Claims

1. A receiving unit that generates a received signal based on a first radio signal received by a first antenna and a second radio signal received by a second antenna, An adaptive equivalence processing unit performs adaptive equivalence processing to asymptotically approach the received signal to a predetermined training signal, A receiving device equipped with the following features.

2. The adaptive equivalent processing unit is A Finite Impulse Response (FIR) filter for filtering the received signal, A calculation unit that calculates the difference between the filtered received signal and the predetermined training signal, An adaptive algorithm unit controls the filter characteristics of the FIR filter based on the calculated difference according to the adaptive algorithm, The receiving device according to claim 1, including the following:

3. The receiving unit includes a combining unit that combines the first wireless signal and the second wireless signal to generate the received signal. The receiving device according to claim 1.

4. The receiving unit includes a phase adjustment unit that adjusts the phase difference between the first radio signal and the second radio signal to be combined. The receiving device according to claim 3.

5. The synthesis unit includes the phase adjustment unit, The receiving device according to claim 4.

6. The adaptive equivalence processing unit includes a phase difference calculation unit that calculates the phase difference between the received signal after the adaptive equivalence processing and the predetermined training signal. The phase adjustment unit adjusts the phase difference between the first radio signal and the second radio signal based on the calculated phase difference. The receiving device according to claim 4.

7. The phase difference calculation unit calculates the difference between a first phase difference between the received signal after adaptive equivalence processing and the predetermined training signal when the difference between the received signal after adaptive equivalence processing and the predetermined training signal is asymptotically maximized, and a second phase difference between the received signal after adaptive equivalence processing and the predetermined training signal when the difference between the received signal after adaptive equivalence processing and the predetermined training signal is asymptotically minimized. The phase adjustment unit adjusts the phase difference between the first radio signal and the second radio signal based on the difference between the first phase difference and the second phase difference calculated above. The receiving device according to claim 6.

8. The analog front-end circuit including the receiving unit, A digital circuit including the adaptive equivalent processing unit, The receiving device according to claim 1, comprising:

9. The aforementioned analog front-end circuit is A combining circuit for combining the first wireless signal and the second wireless signal, A gain adjustment circuit for adjusting the gain of the synthesized signal, An analog-to-digital (AD) converter that performs AD conversion on the signal with adjusted gain to generate the received signal, The receiving device according to claim 8, including the following:

10. The receiving unit is A first receiving unit that generates a first received signal based on the first wireless signal, A second receiving unit that generates a second received signal based on the second wireless signal, Includes, The adaptive equivalent processing unit is A first adaptive equivalence processing unit that performs a first adaptive equivalence processing to asymptotically approach the first received signal to the predetermined training signal, A second adaptive equivalence processing unit that performs a second adaptive equivalence processing to asymptotically approach the second received signal to the predetermined training signal, The receiving device according to claim 1, including the following:

11. The system includes a combining unit that combines the first received signal after the first adaptive equivalence processing and the second received signal after the second adaptive equivalence processing. The receiving device according to claim 10.

12. Includes a phase adjustment unit that adjusts the phase difference between the first received signal after the first adaptive equivalence processing and the second received signal after the second adaptive equivalence processing. The receiving device according to claim 11.

13. The first adaptive equivalence processing unit includes a first phase difference calculation unit that calculates a first phase difference between the first received signal after the first adaptive equivalence processing and the predetermined training signal. The second adaptive equivalence processing unit includes a second phase difference calculation unit that calculates a second phase difference between the second received signal after the second adaptive equivalence processing and the predetermined training signal. The phase adjustment unit adjusts the phase difference between the first received signal after the first adaptive equivalence processing and the second received signal after the second adaptive equivalence processing based on the first phase difference calculated and the second phase difference calculated. The receiving device according to claim 12.

14. A received signal is generated based on a first radio signal received by a first antenna and a second radio signal received by a second antenna. Adaptive equivalence processing is performed to asymptotically approach a predetermined training signal with the received signal. Reception method.

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