Transmitting device, receiving device, transmitting method, and receiving method

Abstract

To provide a transmitting device and a receiving device that enable beamforming with high performance and low power consumption.SOLUTION: In a communication device 100, a dither signal generation unit 120 generates different pseudorandom sequences {0 or 1} for lower bits of a DACs as dither signals. In DACs 125-1 to 125-N, after adding the pseudorandom sequences to lower bits of a main signal beamformed by precoding, those bits are truncated, and conversion processing to analog signals is performed only for higher bits.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a transmitting device, a receiving device, a transmitting method, and a receiving method that have a function of performing beamforming in wireless transmission. [Background technology]

[0002] One of the main technologies for 5G mobile communication systems is 5G multi-antenna technology (Non-Patent Document 1). 5G multi-antenna technology uses beamforming, which adaptively controls antenna directivity using a massively multi-element antenna, to compensate for propagation loss in high frequency bands. Beamforming can be broadly divided into the following three types (Chapter 3.3 of Non-Patent Document 1). (1) Fully digital beamforming (2) Full analog beamforming (3) Hybrid Beamforming

[0003] (1) Full digital beamforming has excellent performance due to digital precoding processing, but requires the same number of digital to analog converters (DAC) and up converters (UC) as the number of antenna elements, which makes it expensive in high frequency bands and consumes relatively high power.

[0004] (2) Full analog beamforming does not require digital precoding processing and has the simplest circuit configuration, but it requires reducing the number of beams and generating narrow beams to maintain orthogonality between beams.

[0005] (3) Hybrid beamforming uses a mixture of digital and analog to perform beamforming, so its performance and circuit complexity are intermediate between (1) full digital beamforming and (2) full analog beamforming.

[0006] Meanwhile, the environment and technological development are progressing internationally toward the commercialization of HAPS (High-Altitude Platform Station), and its widespread use is expected. In particular, there are high expectations for fixed communication systems using HAPS to secure redundant routes for backhaul lines via the sky. It is expected that a high-speed, large-capacity HAPS system will be realized in conjunction with a 5G network using the 38 GHz band allocated to HAPS at WRC-19 (World Radiocommunication Conference 2019) (Non-Patent Document 2). HAPS flies in a circle in the stratosphere at an altitude of about 20 km, so it follows by performing beamforming between the ground station. HAPS requires the use of a massive element antenna to compensate for propagation loss in high frequency bands. However, power consumption is an issue for solar-powered HAPS, and this issue becomes more pronounced especially when (1) full digital beamforming is adopted to ensure performance.

[0007] As a method for reducing power consumption, the number of bits of the DAC in transmit beamforming and the number of bits of the analog-to-digital converter (ADC) in receive beamforming can be mentioned. In order to reduce the influence of quantization error when reducing the number of bits, a dither technique is applied to receive beamforming in Patent Document 1. When the ADC output is expressed as an integer, the analog input 1.51 is quantized to a digital output 2, and the quantization error is 0.49. By generating amplitudes of -0.375, -0.125, 0.125, and 0.375 with 4 sample clocks as one period as pseudo noise (dither signal) and adding them to the analog input 1.51, the analog input 1.51 is converted to 1.135, 1.385, 1.635, or 1.885 with an equal probability of 1 / 4, and the average of the quantization error can be set to 0.

[0008] In addition, in any of the beamforming methods (1) to (3) above, calibration between elements is important when controlling the phase (delay) of each antenna element, since there is variation in the analog circuit characteristics between elements. In particular, the stratosphere at an altitude of around 20 km where HAPS resides is a harsh environment with extremely low temperatures of -70°C and pressure of 1 / 10 atmospheric pressure, so real-time and high-speed calibration between elements is required.

[0009] In Patent Document 2, a pseudo-random sequence is added to a main signal, which is then sent from an array antenna, received by a receiving array antenna, and the characteristics of each antenna element are calculated by finding the correlation between the received signal and the pseudo-random sequence that is the same as that used on the transmitting side, and inter-element calibration is then performed, making it possible to perform real-time calibration without stopping the main signal. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Japanese Patent Application Publication No. 6-237928 [Patent Document 2] Special Publication No. 2010-540894 [Non-patent literature]

[0011] [Non-Patent Document 1] Suyama et al., "5G Multi-Antenna Technology," NTT DOCOMO Technical Journal, Vol. 23 No. 4, pp. 30-39 (January 2016) [Non-Patent Document 2] Suzuki et al., "Development of a 38GHz wireless communication system in conjunction with a 5G network using a high altitude platform (HAPS) - Study on high-speed, high-capacity backhaul lines for the 5G network -", 2021 Institute of Electronics, Information and Communication Engineers General Conference, B-3-1 (March 2021) Summary of the Invention [Problem to be solved by the invention]

[0012] As mentioned above, fixed communication systems using HAPS are expected to realize high speed and large capacity in the 38 GHz band. However, when using the 38 GHz band, which has high rain attenuation, it is assumed that a massive element antenna will be used to compensate for propagation loss in the high frequency band, and the number of elements will need to be further increased to ensure a sufficient rain attenuation margin, making the issue of power consumption even more pronounced.

[0013] The specific embodiments of the present disclosure contribute to providing a transmitting device, a receiving device, a transmitting method, and a receiving method that enable high-performance, low-power beamforming. [Means for solving the problem]

[0014] The transmitting device of the present disclosure has a function of performing beamforming, and includes a plurality of digital-to-analog conversion units that convert digital signals corresponding to each of a plurality of antenna elements into analog signals, and a dither signal generation unit that generates different pseudo-random sequences as dither signals for the lower bits of the digital signals of the digital-to-analog conversion units, and the digital-to-analog conversion units add the dither signal generated by the dither signal generation units to the lower bits of the digital signal, and perform a conversion process to an analog signal only on the upper bits of the digital signal.

[0015] The receiving device of the present disclosure has a function of performing beamforming and includes a plurality of analog / digital conversion units that convert analog signals corresponding to each of a plurality of antenna elements into digital signals, and a dither signal generation unit that generates different pseudo-random sequences as dither signals for the lower bits of the digital signal output from the analog / digital conversion units, and the analog / digital conversion unit adds the dither signal generated by the dither signal generation unit to the analog signal at a power level equivalent to the lower bits of the digital signal, and performs a conversion process to a digital signal only for the portion equivalent to the upper bits of the digital signal.

[0016] The transmission method disclosed herein has a function of performing beamforming and includes a plurality of digital-to-analog conversion steps for converting digital signals corresponding to a plurality of antenna elements into analog signals, and a dither signal generation step for generating different pseudo-random sequences as dither signals for the lower bits of the digital signals obtained in the digital-to-analog conversion steps, wherein the digital-to-analog conversion step adds the dither signal generated in the dither signal generation step to the lower bits of the digital signals, and performs a conversion process to an analog signal only on the upper bits of the digital signals.

[0017] The receiving method disclosed herein has a function of performing beamforming, and includes a plurality of analog / digital conversion steps for converting analog signals corresponding to each of a plurality of antenna elements into a digital signal, and a dither signal generation step for generating a different pseudo-random sequence as a dither signal for each of the lower bits of the digital signal obtained in the analog / digital conversion steps, wherein the analog / digital conversion step adds the dither signal generated in the dither signal generation step to the analog signal at a power level corresponding to the lower bits of the digital signal, and performs a conversion process to a digital signal only for a portion corresponding to the upper bits of the digital signal.

[0018] These comprehensive or specific aspects may be realized as a system, an apparatus, a method, an integrated circuit, a computer program, or a recording medium, or may be realized as any combination of a system, an apparatus, a method, an integrated circuit, a computer program, and a recording medium. Effect of the Invention

[0019] According to one embodiment of the present disclosure, a dither signal can be generated in a simple manner, thereby reducing the number of bits of a DAC or ADC while preventing the effects of quantization errors, thereby achieving high-performance, low-power beamforming.

[0020] Further advantages and benefits of an embodiment of the present disclosure will become apparent from the specification and drawings. Such advantages and / or benefits may be provided by some of the embodiments and features described in the specification and drawings, respectively, but not necessarily all of them may be provided to obtain one or more identical features. [Brief description of the drawings]

[0021] [Figure 1] 1 is a diagram illustrating a configuration of a communication device according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a diagram showing a configuration of a DAC using ΔΣ conversion as an example in the first embodiment of the present invention. [Diagram 3] FIG. 4 is a diagram illustrating an example of the operation of a final quantization unit and a dither signal generation unit in the first embodiment of the present invention. [Figure 4] FIG. 2 is a diagram illustrating a configuration of an ADC using ΔΣ conversion as an example in the first embodiment of the present invention. [Diagram 5] FIG. 4 is a diagram illustrating an example of the operation of a quantization unit and a dither signal generation unit in the first embodiment of the present invention. [Figure 6] FIG. 11 is a diagram illustrating a configuration of a communication device according to a second embodiment of the present invention. [Figure 7] FIG. 11 is a diagram showing the configuration of a DAC using ΔΣ conversion as an example in a second embodiment of the present invention. [Figure 8] FIG. 11 is a diagram illustrating an example of the operation of a final quantization unit and a dither signal generation unit in the second embodiment of the present invention. [Figure 9] FIG. 11 is a diagram illustrating a configuration of an ADC using ΔΣ conversion as an example in a second embodiment of the present invention. [Figure 10] FIG. 11 is a diagram illustrating an example of the operation of a quantization unit and a dither signal generation unit in the second embodiment of the present invention. [Figure 11] FIG. 11 is a diagram illustrating a configuration of a communication device according to a third embodiment of the present invention. [Figure 12] FIG. 11 is a diagram illustrating a configuration of a transmission characteristic calculation analog unit in accordance with a third embodiment of the present invention. [Figure 13]FIG. 11 is a diagram illustrating a configuration of a transmission and reception characteristic calculation unit in the third embodiment of the present invention. [Figure 14] FIG. 11 is a diagram showing a configuration of a reception characteristics calculation analog section in accordance with a third embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] Hereinafter, the embodiments of the present disclosure will be described in detail with reference to the drawings as appropriate. However, more detailed explanation than necessary may be omitted. For example, detailed explanation of already well-known matters or duplicate explanation of substantially the same configuration may be omitted. This is to avoid the following explanation becoming unnecessarily redundant and to facilitate understanding by those skilled in the art.

[0023] It should be noted that the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter described in the claims.

[0024] (Embodiment 1) 1 is a diagram showing a configuration of a communication device 100. The communication device 100 includes M transmission signal generating units 110-1 to M, a transmission digital precoding unit 115, a dither signal generating unit 120, N DACs 125-1 to N, N UCs 130-1 to N, N power amplifiers 135-1 to N, N duplexers 140-1 to N, N antenna elements 145-1 to N, L reception signal regenerating units 210-1 to L, a reception digital precoding unit 215, N ADCs 225-1 to N, N DCs 230-1 to N, and N power amplifiers 235-1 to N. Note that the components that perform digital processing in the communication device 100 may be integrated circuits 105. The components that perform digital processing include transmission signal generation units 110-1 to 110-M, transmission digital precoding unit 115, dither signal generation unit 120, DACs 125-1 to 125-N, reception signal generation units 210-1 to 210-L, reception digital precoding unit 215, and ADCs 225-1 to 225-N. Note that integrated circuit 105 may include not only the components that perform digital processing, but also some or all of the components that perform analog processing.

[0025] The following describes the transmission side of the operation of the communication device 100 in FIG. 1. The transmission signal generating units 110-1 to 110-M generate transmission streams 1 to 1. The transmission digital precoding unit 115 performs digital precoding for beamforming on M inputs and generates N digital signals (main signals) corresponding to the N antenna elements. The dither signal generating unit 120 generates a dither signal. The DACs 125-1 to 125-N also use the dither signal to convert the digital signal into an analog signal. The UCs 130-1 to 130-N upconvert the analog signal to a transmission frequency band. The power amplifying units 135-1 to 135-N amplify the power of the upconverted analog signal. The analog signals output from the power amplifying units 135-1 to 135-N pass through the duplexers 140-1 to 140-N, respectively, and are output as transmission signals from the N antenna elements 145-1 to 145-N.

[0026] Fig. 2 is a diagram showing the configuration of the DAC125-K using ΔΣ conversion as an example. The DAC125-K includes a final quantization unit 150 and an LPF (Low Pass Filter) 155. In the DAC125-K in Fig. 2, the final quantization unit 150 performs final quantization before analog conversion using a digital signal (main signal) corresponding to the antenna element K output from the transmission digital precoding unit 115 and a dither signal output from the dither signal generation unit 120. The LPF 155 passes only low-frequency signals from the digital signal output from the final quantization unit 150, converts it into an analog signal, and outputs it to the UC130-K.

[0027] 3 is a diagram showing an example of the operation of the final quantization unit 150 and the dither signal generation unit 120. The main signal input to the final quantization unit 150 is a 10-bit digital signal, and 1 bit and 2 bits (2 3 ~2 2 ) and set the remaining 7 bits to 2 1 ~2 -5 The dither signal generating unit 120 is expressed as follows:-1 ~2 -5 The final quantization unit 150 generates a different pseudo-random sequence for each of the 10-bit main signal and the 2 -1 ~2 -5 The final quantization unit 150 adds a different pseudo-random sequence {0 or 1} to each of the 10-bit main signals, discards the lowest 5 bits, and outputs a 5-bit digital signal to the LPF 155. Note that examples of pseudo-random sequences include M sequences and Gold sequences, and can be used as dither signals because 0 and 1 are generated with approximately equal probability. Therefore, the final quantization unit 150 adds 0 to 2, which are generated with approximately equal probability, to the 10-bit main signal. 0 -2 -5 is added and the lowest 5 bits are discarded.

[0028] With the above configuration, a dither signal can be generated in a simple manner, thereby providing a transmitting device that reduces the number of DAC bits while preventing the effects of quantization error, enabling high-performance, low-power beamforming.

[0029] Next, the receiving side of the operation of the communication device 100 in FIG. 1 will be described. Analog signals received by N antenna elements 145-1 to N pass through duplexers 140-1 to N, respectively, and are input to power amplifiers 235-1 to N. The power amplifiers 235-1 to N amplify the power of the analog signals. The DCs 230-1 to N down-convert the analog signals from the reception frequency band, respectively. The ADCs 225-1 to N also use a dither signal, respectively, to convert the analog signals (main signals) into digital signals. The reception digital precoding unit 215 performs digital precoding for beamforming on the N inputs, and generates L digital signals corresponding to the L reception streams, respectively. The reception signal generation units 210-1 to L perform error correction decoding and demodulation processing, and regenerate the L reception streams from the reception signals.

[0030] FIG. 4 is a diagram showing the configuration of the ADC225-K using ΔΣ conversion as an example. The ADC225-K includes a quantizer 250, an integrator 255, and a subtractor 260. In the ADC225-K of FIG. 4, the subtractor 260 subtracts the output signal from the quantizer 250 from the analog signal corresponding to the antenna element K output from the DC230-K. The integrator 255 performs integration processing and outputs an analog signal (main signal). The quantizer 250 performs quantization of digital conversion using the analog signal (main signal) and the dither signal output from the dither signal generator 120. As described above, the ADC225-K converts into a digital signal by ΔΣ conversion and outputs it to the receiving digital precoding unit 215.

[0031] 5 is a diagram showing an example of the operation of the quantizer 250 and the dither signal generator 120. The signal output from the quantizer 250 is a 5-bit digital signal, and 1 bit and 2 bits (2 3 ~2 2 ) and set the remaining 2 bits to 2 1 ~2 0 The dither signal generating unit 120 is expressed as follows: -1 ~2 -5 The quantizer 250 generates a different pseudo-random sequence for each of the analog signals (main signals) as a dither signal. -1 ~2 -5 A different pseudorandom sequence for each of the digital signals -1 ~2 -5 The pseudorandom sequence is added at a power level corresponding to the power level of 0, truncated to the most significant 5 bits, and output as a digital signal to the receiving digital precoding unit 215. Note that an M sequence or a Gold sequence can be given as an example of the pseudorandom sequence. Since 0 and 1 are generated with approximately equal probability, it can be used as a dither signal. Therefore, the quantization unit 250 converts 0 to 2, which are generated with approximately equal probability, into the analog signal (main signal). 0 -2 -5 is added and then truncated to the most significant 5 bits.

[0032] With the above configuration, a dither signal can be generated in a simple manner, thereby providing a receiving device that reduces the number of ADC bits while preventing the effects of quantization error, enabling high-performance, low-power beamforming.

[0033] (Embodiment 2) 6 is a diagram showing a configuration of a communication device 300 according to a second embodiment of the present invention. The same components as those in the communication device according to the first embodiment are designated by the same reference numerals, and the description thereof will be omitted. The second embodiment enables high-performance and low-power beamforming by controlling effective antenna elements.

[0034] 6 is compared to the communication device 100 in the first embodiment shown in FIG. 1, the transmission digital precoding unit 115, the dither signal generating unit 120, the N DACs 125-1 to N, the N UCs 130-1 to N, the N power amplifiers 135-1 to N, the reception digital precoding unit 215, the N ADCs 225-1 to N, the N DCs 230-1 to N, and the N power amplifiers 235-1 to N are replaced with a transmission digital precoding unit 315, a dither signal generating unit 320, N DACs 325-1 to N, N UCs 330-1 to N, N power amplifiers 335-1 to N, a reception digital precoding unit 415, N ADCs 425-1 to N, N DCs 430-1 to N, and N power amplifiers 435-1 to N, and an effective antenna element control unit 365 is added. Incidentally, among the components of the communication device 300 that perform digital processing, the integrated circuit 305 may be used. The components that perform digital processing include the transmission signal generating units 110-1 to 110-M, the transmission digital precoding unit 315, the dither signal generating unit 320, the DACs 325-1 to 110-N, the reception signal regenerating units 210-1 to 110-L, the reception digital precoding unit 415, and the ADCs 425-1 to 110-N. Incidentally, the integrated circuit 305 may include not only the components that perform digital processing, but also some or all of the components that perform analog processing.

[0035] The following describes the transmission side of the operation of the communication device 300 in Fig. 3. The effective antenna element control unit 365 determines effective antenna elements among all antenna elements according to the transmission path conditions and the remaining battery power of the communication device 300, and outputs effective antenna element information. Each component described below operates based on the effective antenna element information.

[0036] The digital precoding unit for transmission 315 performs digital precoding for beamforming on M inputs, and generates N digital signals (main signals) corresponding to the N antenna elements, respectively. However, the digital precoding unit for transmission 315 generates 0 (null) for the invalid antenna elements. The dither signal generating unit 320 generates a dither signal. Each of the DACs 325-1 to 325-N converts a digital signal into an analog signal using the dither signal as well. However, the operation of the DAC for the invalid antenna elements is stopped. As a result, 0 (null) is output. Each of the UCs 330-1 to 330-N upconverts an analog signal to a transmission frequency band. However, the operation of the UC for the invalid antenna elements is stopped. As a result, 0 (null) is output. Each of the power amplifiers 335-1 to 335-N amplifies the power of the upconverted analog signal. However, the operation of the power amplification for the invalid antenna elements is stopped. As a result, 0 (null) is output.

[0037] Fig. 7 is a diagram showing the configuration of DAC325-K using ΔΣ conversion as an example. Compared to DAC125-K in the first embodiment shown in Fig. 2, DAC325-K has a configuration in which final quantization unit 150 is replaced with final quantization unit 350 and a sampling frequency conversion unit 370 is added. Each component described below operates based on effective antenna element information.

[0038] In the DAC325-K of FIG. 7, the sampling frequency conversion unit 370 converts the sampling frequency so that the sampling frequency is lowered as the number of effective antenna elements increases. For example, when the number of effective antenna elements is changed from 256 to 1024, which is four times, the sampling frequency is lowered to 1 / 2. The final quantization unit 350 performs final quantization before analog conversion using the digital signal (main signal) corresponding to the antenna element K output from the transmission digital precoding unit 315 and the dither signal output from the dither signal generation unit 320. At this time, the number of quantization bits is reduced as the number of effective antenna elements increases. For example, when the number of effective antenna elements is changed from 256 to 1024, which is four times, the number of quantization bits is reduced by 1 bit.

[0039] 8 is a diagram showing an example of the operation of the final quantization unit 350 and the dither signal generation unit 320. As in the example in the first embodiment shown in FIG. 3, the main signal input to the final quantization unit 350 is a 10-bit digital signal, and 1 bit of code and 2 bits (2 3 ~2 2 ) and set the remaining 7 bits to 2 1 ~2 -5 In the example of the first embodiment shown in FIG. 3, it is assumed that the number of effective antenna elements is 256 and that the number of effective antenna elements is changed from 256 to 1024, four times as many as the first embodiment. 0 ~2 -5 The final quantization unit 350 generates a different pseudo-random sequence for each of the 10-bit main signal and the 2 0 ~2 -5 The final quantization unit 350 adds different pseudo-random sequences to each of the 10-bit main signals, discards the lowest 6 bits, and outputs a 4-bit digital signal to the LPF 155. Note that examples of pseudo-random sequences include M sequences and Gold sequences, and can be used as dither signals because 0 and 1 are generated with approximately equal probability. 1 -2 -5is added and the lowest 6 bits are discarded.

[0040] With the above configuration, it is possible to provide a transmitting device that enables high-performance, low-power beamforming by changing the sampling rate and number of bits of the DAC while preventing the effects of quantization error in accordance with effective antenna element information.

[0041] Next, a description will be given of the receiving side of the operation of the communication device 300 in Fig. 6. Each component described below operates based on effective antenna element information.

[0042] The power amplifiers 435-1 to 435-N amplify the power of the analog signals that have passed through the duplexers 140-1 to 140-N. However, the power amplification operation for the disabled antenna elements is stopped. As a result, 0 (null) is output. The DCs 430-1 to 430-N down-convert the analog signals from the reception frequency band. However, the UC operation for the disabled antenna elements is stopped. As a result, 0 (null) is output. The ADCs 425-1 to 425-N convert the analog signals (main signals) into digital signals using a dither signal as well. However, the ADC operation for the disabled antenna elements is stopped. As a result, 0 (null) is output. The reception digital precoding unit 415 performs digital precoding for beamforming on N inputs, and generates L digital signals corresponding to the L streams. However, the input from the disabled antenna elements is 0 (null). As a result, beamforming is performed on the input from the valid antenna elements.

[0043] Fig. 9 is a diagram showing the configuration of the ADC425-K using ΔΣ conversion as an example. Compared to the ADC225-K in the first embodiment shown in Fig. 4, the ADC425-K has a configuration in which the quantization unit 250 is replaced with a quantization unit 450 and a sampling frequency conversion unit 470 is added. Each component described below operates based on effective antenna element information.

[0044] In the ADC 425-K in FIG. 9, the sampling frequency conversion unit 470 converts the sampling frequency so that the sampling frequency is lowered as the number of effective antenna elements increases. For example, when the number of effective antenna elements is changed from 256 to 1024, the sampling frequency conversion unit 470 lowers the sampling frequency by half. The quantization unit 450 performs quantization of the digital conversion using the analog signal (main signal) and the dither signal output from the dither signal generation unit 120. At this time, the number of quantization bits is reduced as the number of effective antenna elements increases. For example, when the number of effective antenna elements is changed from 256 to 1024, the number of quantization bits is reduced by 1 bit.

[0045] Fig. 10 is a diagram showing an example of the operation of the quantization unit 450 and the dither signal generation unit 320. In the example of the first embodiment shown in Fig. 5, it is assumed that the number of effective antenna elements is 256 and is changed from 256 to 1024, which is four times the number. The dither signal generation unit 320 performs the following operations. 0 ~2 -5 The quantizer 450 generates a different pseudo-random sequence for each of the analog signals (main signals) as a dither signal. 0 ~2 -5 A different pseudorandom sequence for each of the digital signals 0 ~2 -5 The quantization unit 450 adds the power levels corresponding to the analog signal (main signal) at a power level equivalent to the power level 0, truncates the power level to the most significant 4 bits, and outputs the resulting digital signal to the reception digital precoding unit 415. Note that the pseudo-random sequence may be, for example, an M sequence or a Gold sequence, and can be used as a dither signal by generating 0 and 1 with approximately equal probability. Therefore, the quantization unit 450 quantizes the analog signal (main signal) at a power level equivalent to the power level 0, 1, and 2, which are generated with approximately equal probability. 1 -2 -5 is added and then truncated to the most significant 4 bits.

[0046] With the above configuration, it is possible to provide a receiving device that enables high-performance, low-power beamforming by changing the sampling rate and bit number of the ADC while preventing the effects of quantization error in accordance with effective antenna element information.

[0047] (Embodiment 3) 11 is a diagram showing a configuration of a communication device 500 according to the third embodiment of the present invention. The same components as those in the communication device according to the first embodiment are given the same reference numerals, and the description thereof will be omitted. In the third embodiment, a calibration signal and a dither signal are used in combination, thereby maintaining constant beamforming performance through high-speed real-time calibration.

[0048] The communication device 500 in FIG. 11 adopts a configuration in which N transmission characteristic correction units 575-1 to N, a transmission characteristic calculation analog unit 580, a reception characteristic calculation analog unit 585, a transmission and reception characteristic calculation unit 590, N adders 595-1 to N, and N reception characteristic correction units 675-1 to N are added to the communication device 100 in the first embodiment shown in FIG. 1. Note that, among the components of the communication device 500, the components that perform digital processing may be an integrated circuit 505. The components that perform digital processing include the transmission signal generation units 110-1 to M, the transmission digital precoding unit 115, the dither signal generation unit 120, the DACs 125-1 to N, the reception signal regeneration units 210-1 to L, the reception digital precoding unit 215, the ADCs 225-1 to N, the transmission characteristic correction units 575-1 to N, the transmission and reception characteristic calculation unit 590, and the reception characteristic correction units 675-1 to N. It should be noted that the integrated circuit 505 may include not only components that perform digital processing, but also some or all of the components that perform analog processing.

[0049] The following describes the transmission side of the operation of the communication device 500 in FIG. 11. The transmission characteristic correction units 575-1 to N perform inter-element calibration by correcting the characteristics of the digital signal (main signal) output from the transmission digital precoding unit 115 based on the transmission characteristic correction amount signal output from the transmission characteristic calculation unit 590. After the output signals from the transmission characteristic correction units 575-1 to N pass through the DACs 125-1 to N, UCs 130-1 to N, power amplifiers 135-1 to N, duplexers 140-1 to N, and adders 595-1 to N, the transmission characteristic calculation analog unit 580 performs the process described below. In addition, in the communication device 500, when the transmission and reception frequencies are different, only the transmission side signal is output from the transmission characteristic calculation analog unit 580. The transmission and reception characteristic calculation unit 590 calculates the transmission characteristics using the output signal from the transmission characteristic calculation analog unit 580.

[0050] 12 is a diagram showing a configuration of the transmission characteristic calculation analog unit 580. The transmission characteristic calculation analog unit 580 includes an ADC 825, a DC 830, a power amplifier 835, and an input selection switch 837. The input selection switch 837 sequentially selects and outputs one of the N antenna elements 145-1 to N. The power amplifier 835 amplifies the power of the analog signal. Like the DCs 230-1 to N, the DC 830 down-converts the analog signal from the reception frequency band. The ADC 825 converts the analog signal into a digital signal.

[0051] 13 is a diagram showing the configuration of the transmission / reception characteristic calculation unit 590. The transmission / reception characteristic calculation unit 590 includes correlation calculation units 743 and 843, peak detection units 747 and 847, a transmission characteristic comparison unit 753, a reception characteristic comparison unit 853, and an input selection switch 841. The correlation calculation unit 743 compares the digital signal output from the transmission characteristic calculation analog unit 580 with the most significant bit (2 -1) and a correlation calculation is performed with a pseudo random sequence. Peak detection unit 747 detects a peak value within one period of the pseudo random sequence, and performs correlation calculation over multiple periods as necessary to obtain a desired correlation gain. Output from transmission characteristic calculation analog unit 580 is switched sequentially to each of N antenna elements 145-1 to N. Transmission characteristic comparison unit 753 compares the characteristics of each of N antenna elements 145-1 to N, and outputs each transmission characteristic correction amount to transmission characteristic correction units 575-1 to N so that all characteristics are the same.

[0052] With the above configuration, it is possible to provide a transmitter that can maintain constant beamforming performance by high-speed real-time calibration by using both a calibration signal and a dither signal. In other words, a signal that can be used both as a calibration signal and a dither signal can be added to the most significant bit (2 -1 ), the power level of the calibration signal can be set high, and the desired correlation gain can be kept low, enabling high-speed real-time calibration.

[0053] Next, the receiving side of the operation of the communication device 500 in Fig. 11 will be described. The analog unit for calculating reception characteristics 585 performs analog processing on the dither signal output from the dither signal generating unit 120 to generate high frequency analog signals for the antenna elements 145-1 to N. The adders 595-1 to N add the high frequency analog signals to the analog signals received by the N antenna elements 145-1 to N, respectively. The outputs from the adders 595-1 to N pass through the duplexers 140-1 to N, the power amplifiers 235-1 to N, the DCs 230-1 to N, and the ADCs 225-1 to N, respectively. The transmission and reception characteristics calculating unit 590 calculates the reception characteristics using the output signals from the ADCs 225-1 to N, and generates a reception characteristics correction amount signal. The reception characteristic correction units 675-1 to 675-N perform inter-element calibration by correcting the characteristics of the digital signals output from the ADCs 225-1 to 225-N, respectively, based on the reception characteristic correction amount signal output from the transmission and reception characteristic calculation unit 590.

[0054] 14 is a diagram showing a configuration of the reception characteristic calculation analog unit 585. The reception characteristic calculation analog unit 585 includes a format conversion unit 723, a DAC 725, a UC 730, a power amplification unit 735, and an output changeover switch 737. The format conversion unit 723 converts the most significant bit (2 -1 ) from a format {0 or 1} of the pseudo-random sequence for the N antenna elements 145-1 to N to {-1 or 1}. The DAC 725 converts the digital signal into an analog signal. Like the UCs 130-1 to N, the UCs 730 upconvert each analog signal to the transmission frequency band. Like the power amplifiers 135-1 to N, the power amplifier 735 amplifies the power of the upconverted analog signal. The output changeover switch 737 sequentially selects and outputs one of the outputs from the adders 595-1 to N, and outputs 0 (null) to the others. Through the above operations, the adders 595-1 to N calculate 2 -1 The pseudorandom sequence for the digital signal is -1 The power level is then added up to the power level corresponding to the

[0055] In the transmission / reception characteristic calculation unit 590 in FIG. 13, an input selection switch 841 selects and outputs the output of the ADC 225-1 to 225-N for which a calibration signal has been output from the reception characteristic calculation analog unit 585. A correlation calculation unit 843 calculates the correlation between the digital signal output from the input selection switch 841 and the most significant bit (2 -1 ) and a correlation calculation is performed with a pseudo random sequence. Peak detection unit 847 detects a peak value within one period of the pseudo random sequence, and performs correlation calculation over multiple periods as necessary to obtain a desired correlation gain. The output from reception characteristic calculation analog unit 585 is switched sequentially to each of N antenna elements 145-1 to N. Reception characteristic comparison unit 853 compares the characteristics of each of N antenna elements 145-1 to N, and outputs the amount of reception characteristic correction for each to reception characteristic correction units 675-1 to N so that all the characteristics are the same.

[0056] With the above configuration, it is possible to provide a receiver that can maintain constant beamforming performance through high-speed real-time calibration by using both a calibration signal and a dither signal. In other words, a signal that can be used both as a calibration signal and a dither signal can be added to the most significant bit (2 -1 ), the power level of the calibration signal can be set high, and the desired correlation gain can be kept low, enabling high-speed real-time calibration.

[0057] (supplement) The above describes the embodiments with reference to the drawings, but the present disclosure is not limited to the contents described in the above embodiments 1 to 3, and may be implemented in any form for achieving the purpose of the present disclosure and related or incidental objects, for example, the following.

[0058] (1) In the first to third embodiments, a full digital beamforming configuration is used, but the present disclosure is not limited to this, and a hybrid beamforming configuration may also be used. In this case, the same effects can also be obtained.

[0059] (2) In the first to third embodiments, the pseudo-random sequence {0 or 1} is added to the lower bits and then truncated to perform quantization of the DAC and ADC. However, the present disclosure is not limited to this. Quantization may be performed in other configurations, such as converting the pseudo-random sequence {0 or 1} to {-1 or 1} and, when the lower bits indicate a negative value, rounding after adding the upper bits as well as the lower bits as a negative value.

[0060] (3) In the second embodiment, when the number of effective antenna elements is changed fourfold from 256 to 1024, the sampling frequency is reduced to 1 / 2. However, the present disclosure is not limited to this, and the degree of change in the number of elements and the degree of change in the sampling frequency may be determined by a different formula, etc.

[0061] (4) In the second embodiment, when the number of effective antenna elements is changed fourfold from 256 to 1024, the number of quantization bits of the DAC and ADC is reduced by 1 bit. However, the present disclosure is not limited to this, and the degree of change in the number of elements and the degree of change in the number of quantization bits may be determined by a different formula or the like.

[0062] (5) Some of the first to third embodiments may be combined with each other.

[0063] (6) In embodiments 1 to 3, the notation "... part" used for each component may be replaced with other notations such as "... circuitry," "... assembly," "... device," "... unit," or "... module."

[0064] (7) The present disclosure may relate to implementations using hardware and software. The above embodiments may be implemented or performed using a computing device (processor). The computing device or processor may be, for example, a main processor / general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), other programmable logic devices, etc. The above embodiments may be performed or realized by a combination of these devices.

[0065] (8) The first to third embodiments may be realized by a mechanism of software modules executed by a processor or directly by hardware. Also, a combination of software modules and hardware implementation is possible. The software modules may be stored in various types of computer readable storage media, such as RAM, EPROM, EEPROM, flash memory, registers, hard disks, CD-ROM, DVD, etc.

[0066] (9) In the receiving side of the first to third embodiments, a pseudo-random sequence is used as a dither signal to reduce the number of bits of the ADC. However, the present disclosure is not limited to this. The number of bits of the ADC may be reduced without using a pseudo-random sequence by using thermal noise generated in an analog section as a dither signal. [Industrial Applicability]

[0067] The present disclosure is not limited to HAPS but can be applied to beamforming technology in wireless transmission. [Explanation of symbols]

[0068] 100, 300, 500 Communication Equipment 110 Transmission signal generator 115, 315 Digital precoding unit for transmission 120, 320 Dither signal generator 125, 325, 725 DAC 130, 330, 730UC 135, 235, 335, 435, 735, 835 Power amplifier 140 Duplexer 145 Antenna elements 150, 350 Final quantization section 155 LPF 210 Received signal regeneration unit 215, 415 Digital precoding unit for reception 225, 425, 825 ADCs 230, 430, 830 DC 250, 450 quantization section 255 Integrator 260 Subtractor 365 Effective Antenna Element Control Section 370, 470 Sampling Frequency Conversion Section 575 Transmission characteristic correction section 580 Analog section for calculating transmission characteristics 585 Analog section for calculating reception characteristics 590 Transmission and Reception Characteristics Calculation Unit 595 Adder 675 Reception characteristic correction section 723 Format Conversion Unit 743, 843 Correlation calculation unit 737 Output changeover switch 747,847 Peak detector 753 Transmission Characteristics Comparison Unit 837, 841 Input selection switch 853 Receiving characteristic comparison section

Claims

1. A transmitting device supporting a beamforming function using a plurality of antenna elements, a dither signal generating unit configured to generate a plurality of different pseudo-random sequence signals as a plurality of dither signals for lower bits of a plurality of digital signals corresponding to the plurality of antenna elements, respectively; a plurality of digital / analog conversion units that perform a process of adding the plurality of dither signals generated by the dither signal generation unit to lower bits of the plurality of digital signals and converting only upper bits of a signal resulting from the addition of the plurality of digital signals and the plurality of dither signals into a plurality of analog signals; an effective antenna element control unit that determines an effective antenna element from among the plurality of antenna elements and outputs effective antenna element information corresponding to the determined effective antenna element; having The plurality of digital / analog conversion units determine the number of least significant bits of the plurality of digital signals based on the effective antenna element information. Transmitting device.

2. the plurality of digital / analog conversion units determine a sampling frequency based on the effective antenna element information, and perform a sampling frequency conversion using the determined sampling frequency, and then perform a conversion process into the plurality of analog signals. The transmitting device according to claim 1 .

3. Further comprising a digital precoding unit that outputs the plurality of digital signals for only the effective antenna elements based on the effective antenna element information; The effective antenna element control unit operates the plurality of digital / analog conversion units and analog processing subsequent to the plurality of digital / analog conversion units for only effective antenna elements based on the effective antenna element information. The transmitting device according to claim 1 .

4. A transmitting device supporting a beamforming function using a plurality of antenna elements, comprising: a dither signal generating unit configured to generate a plurality of different pseudo-random sequence signals as a plurality of dither signals for lower bits of a plurality of digital signals corresponding to the plurality of antenna elements, respectively; a plurality of digital / analog conversion units that perform a process of adding the plurality of dither signals generated by the dither signal generation unit to lower bits of the plurality of digital signals and converting only upper bits of a signal resulting from the addition of the plurality of digital signals and the plurality of dither signals into a plurality of analog signals; a plurality of analog / digital converters for converting a plurality of analog signals corresponding to the plurality of antenna elements into a plurality of digital signals in sequence for each element; a transmission characteristic calculation unit that performs correlation calculation between a plurality of pseudo-random sequence signals assigned to the most significant bit of the plurality of pseudo-random sequence signals of the plurality of dither signals generated by the dither signal generation unit and a plurality of digital signals output from the analog / digital conversion unit, sequentially calculates transmission characteristics for each of the plurality of antenna elements, and generates a transmission characteristic correction amount for each of the plurality of antenna elements based on each transmission characteristic; a transmission characteristic correction unit that corrects a transmission characteristic for each antenna element among the plurality of antenna elements based on a transmission characteristic correction amount output from the transmission characteristic calculation unit; A transmitting device having the same.

5. A receiving device that supports a beamforming function using a plurality of antenna elements, a dither signal generating unit that generates a plurality of different pseudo-random sequence signals as a plurality of dither signals; a plurality of analog / digital conversion units which receive a plurality of analog signals and the plurality of dither signals respectively corresponding to the plurality of antenna elements and output a plurality of digital signals, the plurality of dither signals being added to the plurality of analog signals at power levels corresponding to the lower bits of the plurality of digital signals, and performing a process of converting only the portions of the addition results of the plurality of analog signals and the plurality of dither signals corresponding to the upper bits of the plurality of digital signals into the plurality of digital signals; an effective antenna element control unit that determines an effective antenna element from among the plurality of antenna elements and outputs effective antenna element information corresponding to the determined effective antenna element; having The plurality of analog / digital conversion units determine the number of least significant bits of the plurality of digital signals based on the effective antenna element information. Receiving device.

6. the analog-to-digital conversion unit includes a subtractor, an integrator, and a quantization unit; The subtractor subtracts a plurality of output signals of the quantization unit from a plurality of signals respectively corresponding to the plurality of antenna elements; the integrator integrates the output signals of the subtractor and outputs the analog signals; the quantization unit receives the plurality of analog signals and the plurality of dither signals and outputs a plurality of digital signals.

6. The receiving device according to claim 5.

7. the plurality of analog / digital conversion units determine a sampling frequency based on the effective antenna element information, and perform a sampling frequency conversion using the determined sampling frequency, and then perform a conversion process into the plurality of digital signals.

6. The receiving device according to claim 5.

8. Further comprising a digital precoding unit that uses a plurality of signals for only the effective antenna elements based on the effective antenna element information; The effective antenna element control unit operates the plurality of analog / digital conversion units and analog processing before the plurality of analog / digital conversion units only for effective antenna elements based on the effective antenna element information.

6. The receiving device according to claim 5.

9. A receiving device supporting a beamforming function using a plurality of antenna elements, comprising: a dither signal generating unit that generates a plurality of different pseudo-random sequence signals as a plurality of dither signals; a plurality of analog / digital conversion units which receive a plurality of analog signals and the plurality of dither signals respectively corresponding to the plurality of antenna elements and output a plurality of digital signals, the plurality of dither signals being added to the plurality of analog signals at power levels corresponding to the lower bits of the plurality of digital signals, and performing a process of converting only the portions of the addition results of the plurality of analog signals and the plurality of dither signals corresponding to the upper bits of the plurality of digital signals into the plurality of digital signals; a plurality of digital / analog conversion units that convert a pseudo-random sequence signal assigned to a most significant bit of the plurality of pseudo-random sequence signals generated by the dither signal generation unit into a plurality of analog signals and sequentially output the analog signals to a plurality of antenna elements, respectively; a plurality of adders that add up a plurality of received analog signals corresponding to the plurality of antenna elements and a plurality of analog signals output from the plurality of digital / analog conversion units; a reception characteristic calculation unit that performs correlation calculation between a plurality of pseudo-random sequence signals assigned to the most significant bit of the plurality of pseudo-random sequence signals of the plurality of dither signals generated by the dither signal generation unit and a plurality of digital signals output from the analog / digital conversion unit, sequentially calculates reception characteristics for each of the plurality of antenna elements, and generates a reception characteristic correction amount for each of the plurality of antenna elements based on each reception characteristic; a reception characteristic correction unit that corrects reception characteristics for each antenna element among the plurality of antenna elements based on a reception characteristic correction amount output from the reception characteristic calculation unit; A receiving device having the same.

10. A transmission method supporting a beamforming function using multiple antenna elements, comprising: a dither signal generating step of generating a plurality of different pseudo-random sequence signals as a plurality of dither signals for lower bits of a plurality of digital signals respectively corresponding to the plurality of antenna elements; a digital / analog conversion step of adding the plurality of dither signals generated in the dither signal generation step to lower bits of the plurality of digital signals, and converting only upper bits of a result of adding the plurality of digital signals and the plurality of dither signals into a plurality of analog signals; an effective antenna element control step of determining an effective antenna element from among the plurality of antenna elements and outputting effective antenna element information corresponding to the determined effective antenna element; Including, The digital / analog conversion step determines the number of least significant bits of the plurality of digital signals based on the effective antenna element information. Transmission method.

11. an analog / digital conversion step of converting a plurality of analog signals corresponding to each of the plurality of antenna elements into a plurality of digital signals in sequence for each element; a transmission characteristic calculation step of performing correlation calculation between a plurality of pseudo-random sequence signals assigned to the most significant bit of the plurality of pseudo-random sequence signals of the plurality of dither signals generated in the dither signal generation step and a plurality of digital signals obtained in the analog / digital conversion step, sequentially calculating transmission characteristics for each antenna element among the plurality of antenna elements, and generating a transmission characteristic correction amount for each antenna element among the plurality of antenna elements based on each transmission characteristic; a transmission characteristic correction step of correcting a transmission characteristic for each of the antenna elements among a plurality of antenna elements based on the transmission characteristic correction amount generated in the transmission characteristic calculation step; The transmission method of claim 10, further comprising:

12. 1. A receiving method supporting a beamforming function using multiple antenna elements, comprising: a dither signal generating step of generating a plurality of pseudo-random sequence signals as a plurality of dither signals; an analog / digital conversion step of inputting a plurality of analog signals and the plurality of dither signals respectively corresponding to the plurality of antenna elements and outputting a plurality of digital signals, the plurality of dither signals being added to the plurality of analog signals at power levels corresponding to the lower bits of the plurality of digital signals, and converting only the portions of the sum of the plurality of analog signals and the plurality of dither signals corresponding to the upper bits of the plurality of digital signals into the plurality of digital signals; an effective antenna element control step of determining an effective antenna element from among the plurality of antenna elements and outputting effective antenna element information corresponding to the determined effective antenna element; Including, The analog / digital conversion step determines the number of least significant bits of the plurality of digital signals based on the effective antenna element information. Receiving method.

13. a digital / analog conversion step of converting a pseudo-random sequence signal assigned to a most significant bit of the plurality of pseudo-random sequence signals generated in the dither signal generation step into a plurality of analog signals and sequentially outputting the analog signals to a plurality of antenna elements, respectively; a plurality of adding steps for respectively adding a plurality of received analog signals corresponding to the plurality of antenna elements and a plurality of analog signals obtained in the digital / analog conversion step; a reception characteristic calculation step of performing correlation calculation between a plurality of pseudo-random sequence signals assigned to the most significant bit of the plurality of pseudo-random sequence signals of the plurality of dither signals generated in the dither signal generation step and a plurality of digital signals obtained in the analog / digital conversion step, sequentially calculating reception characteristics for each antenna element among the plurality of antenna elements, and generating a reception characteristic correction amount for each antenna element among the plurality of antenna elements based on each reception characteristic; a reception characteristic correction step of correcting the reception characteristic for each antenna element among the plurality of antenna elements based on the reception characteristic correction amount generated in the reception characteristic calculation step; The receiving method according to claim 12, comprising:

14. A program describing a signal processing procedure for executing the transmission method described in claim 10.

15. A program describing a signal processing procedure for executing the receiving method described in claim 12.

16. 1. An integrated circuit supporting a beamforming function using a plurality of antenna elements, comprising: a dither signal generating unit configured to generate a plurality of different pseudo-random sequence signals as a plurality of dither signals for lower bits of a plurality of digital signals corresponding to the plurality of antenna elements, respectively; a plurality of digital / analog conversion units that perform a process of adding the plurality of dither signals generated by the dither signal generation unit to lower bits of the plurality of digital signals and converting only upper bits of a result of adding the plurality of digital signals and the plurality of dither signals into a plurality of analog signals; an effective antenna element control unit that determines an effective antenna element from among the plurality of antenna elements and outputs effective antenna element information corresponding to the determined effective antenna element; having The plurality of digital / analog conversion units determine the number of least significant bits of the plurality of digital signals based on the effective antenna element information. Integrated circuits.

17. 1. An integrated circuit supporting a beamforming function using a plurality of antenna elements, comprising: a dither signal generating unit that generates a plurality of different pseudo-random sequence signals as a plurality of dither signals; an analog / digital conversion unit that receives a plurality of analog signals and the plurality of dither signals corresponding to the plurality of antenna elements, respectively, and outputs a plurality of digital signals, the analog / digital conversion unit adding the plurality of dither signals to the plurality of analog signals at a power level corresponding to the lower bits of the plurality of digital signals, and converting only the portions of the sum of the plurality of analog signals and the plurality of dither signals corresponding to the upper bits of the plurality of digital signals into the plurality of digital signals; an effective antenna element control unit that determines an effective antenna element from among the plurality of antenna elements and outputs effective antenna element information corresponding to the determined effective antenna element; having The plurality of analog / digital conversion units determine the number of least significant bits of the plurality of digital signals based on the effective antenna element information. Integrated circuits.

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