Fully digital beamforming transmitter and transmitting method based on digital radio frequency technology

Abstract

The present application provides a fully digital beamforming transmitter and a transmission method based on digital radio frequency technology. The fully digital beamforming transmitter provided in the present application includes a plurality of baseband signal generators, orthogonal modulators, adders, 1-bit incremental integral modulators, digital-to-analog converters, radio frequency front ends and antennas connected in sequence; each baseband signal generator is connected to one orthogonal modulator and one antenna, one orthogonal modulator includes a plurality of orthogonal modulators, and each baseband signal generator generates a pair of baseband signals; the number of orthogonal modulators in the one orthogonal modulator is the same as the number of adders, the number of 1-bit incremental integral modulators, the number of digital-to-analog converters, the number of radio frequency front ends and the number of antennas; the number of baseband signal generators is the same as the number of beams formed by the antenna, and the number of baseband signal generators is different from the number of orthogonal modulators in one orthogonal modulator.

Description

Technical Field

[0001] The present application relates to the field of high frequency communication technology, and in particular to a fully digital beamforming transmitter and a transmission method based on digital radio frequency technology. Background Art

[0002] In recent years, beamforming technology based on large-scale phased arrays has played an increasingly important role in the field of communications. It can not only compensate for the propagation loss of high-frequency communications, but also achieve flexible signal coverage. Compared with analog beamforming transmitters, all-digital beamforming transmitters can transmit multiple beams at the same time, greatly improving the system user capacity.

[0003] However, in a fully digital beamforming transmitter, each signal requires a transmitter, and the spacing between transmitters is about half the signal wavelength, which makes large-scale arraying very difficult in high-frequency bands with shorter wavelengths. Compared with the signal processing system in the digital domain, the size and cost of the RF front-end in the analog domain account for most of the transmitter as a whole. Therefore, the miniaturization and low cost of the RF front-end circuit in the analog domain are of great significance to the entire system. In the design of traditional RF front-end circuits, an up-converter consisting of a local oscillator and a mixer is required in the analog domain to up-convert the baseband signal to the RF band, making the transmitter architecture complex and difficult to integrate, limiting the performance of the fully digital beamforming transmitter. In addition, the RF loss and noise coefficient of the RF front-end circuit are large, resulting in a low signal-to-noise ratio and difficult to guarantee communication quality. The communication frequency band is fixed, making it difficult to adapt to various communication standards.

[0004] Therefore, there is an urgent need for a fully digital beamforming transmitter based on digital RF technology, which uses digital RF technology to generate RF signals in the digital domain, simplify the RF front-end in the analog domain, and achieve miniaturization and low cost of the RF front-end. In addition, the frequency band of the generated RF signal can be adjusted to adapt to various communication standards. Summary of the invention

[0005] In view of this, the present application provides a fully digital beamforming transmitter and transmission method based on digital RF technology, which is used to utilize digital RF technology to generate RF signals in the digital domain, simplify the RF front end in the analog domain, and achieve miniaturization and low cost of the RF front end. In addition, the frequency band of the generated RF signal can be adjusted to adapt to various communication standards.

[0006] Specifically, the present application is implemented through the following technical solutions:

[0007] The first aspect of the present application provides a fully digital beamforming transmitter based on digital radio frequency technology, wherein the fully digital beamforming transmitter comprises a plurality of baseband signal generators, orthogonal modulators, adders, 1-bit incremental integral modulators, digital-to-analog converters, radio frequency front ends and antennas connected in sequence; wherein:

[0008] Each baseband signal generator is connected to an orthogonal modulator and an antenna, wherein the orthogonal modulator includes a plurality of orthogonal modulators, and each baseband signal generator generates a pair of baseband signals;

[0009] The number of the orthogonal modulators in the one-way orthogonal modulator is the same as the number of the adders, the number of the 1-bit incremental integral modulators, the number of the digital-to-analog converters, the number of the radio frequency front ends, and the number of the antennas; the number of the baseband signal generators is the same as the number of beams formed by the antennas, and the number of the baseband signal generators is different from the number of the orthogonal modulators in the one-way orthogonal modulator;

[0010] The adder is used to aggregate multiple modulated baseband signals in the same direction obtained after being processed by different orthogonal modulators to obtain an aggregated composite signal; the number of the composite signals is the same as the number of the adders;

[0011] The 1-bit delta-sigma modulator is used to convert the multiple composite signals obtained after being processed by the adder into a 1-bit digital signal.

[0012] The second aspect of the present application provides a fully digital beamforming transmission method based on digital radio frequency technology, the method is applied to any one of the fully digital beamforming transmitters provided in the first aspect of the present application, the method comprising:

[0013] Each baseband signal generator generates a pair of baseband signals, and transmits the baseband signals to each corresponding orthogonal modulator;

[0014] Each of the orthogonal modulators up-converts the baseband signal to an intermediate frequency or a radio frequency, and transmits the obtained modulated baseband signal to an adder;

[0015] The adder aggregates multiple modulated baseband signals in the same direction obtained after being processed by different orthogonal modulators, and transmits the obtained aggregated composite signal to the 1-bit incremental integral modulator;

[0016] The 1-bit delta-sigma modulator converts the plurality of composite signals into a 1-bit digital signal, and transmits the digital signal to a digital-to-analog converter;

[0017] The digital-to-analog converter converts the digital signal into a radio frequency signal, and transmits the radio frequency signal to a radio frequency front end;

[0018] The RF front end performs filtering and amplification processing on the RF signal, and transmits the processed RF signal to the corresponding antenna;

[0019] The antenna converts the processed radio frequency signal into electromagnetic waves and radiates them into free space, forming a plurality of beams in different directions; each beam corresponds to a pair of baseband signals generated by a baseband signal generator.

[0020] The present application provides a fully digital beamforming transmitter and a transmitting method based on digital radio frequency technology. In the first aspect, in the fully digital beamforming transmitter provided by the present application, baseband signal processing, modulation, quantization and other operations are all completed by a digital processor, reducing the reliance on analog circuits. Digital signal processing can realize complex signal modulation and processing tasks on relatively simple hardware, reduce system complexity, and the transmitter architecture is simple and easy to integrate, and utilizes large-scale arraying. Traditional radio frequency systems usually rely on a large number of analog circuits for frequency up-conversion, gain control, filtering, modulation, etc. These analog circuits often require precise design and debugging, which increases the complexity and manufacturing cost of the system. In addition, analog circuits are more sensitive to environmental changes (such as temperature, voltage fluctuations, etc.) and are prone to errors. In addition, the present application completes frequency conversion in the digital domain, simplifies the radio frequency front end, realizes the miniaturization and low cost of the radio frequency front end, and provides a basis for large-scale array formation. By transferring the up-conversion process to the digital domain, the transmitter no longer relies on traditional radio frequency components such as mixers, filters and amplifiers, which significantly reduces the complexity of the radio frequency front end and reduces the demand for high-precision radio frequency components, thereby simplifying the design of the entire transmitter. Since the modulation and beamforming of the RF signal are performed in the digital domain, the RF front end only needs to include relatively simple hardware such as digital-to-analog converters, which reduces the number and volume of RF hardware and reduces hardware costs. On the second aspect, traditional RF systems rely on analog circuits to be implemented. The signal processing accuracy of analog circuits is usually limited by device characteristics and environmental conditions (such as temperature, aging, etc.), and may cause large signal distortion and noise. The present application can achieve higher accuracy through digital signal processing and has strong anti-interference capabilities. The 1-bit incremental integral modulator and other digital filters can accurately control the noise distribution and signal quality, improving the overall performance of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A schematic diagram of the structure of a first embodiment of a fully digital beamforming transmitter based on digital radio frequency technology provided in the present application;

[0022] Figure 2 A schematic diagram of the structure of an orthogonal modulator shown in an exemplary embodiment of the present application;

[0023] Figure 3 This is a schematic diagram of the structure of a 1-bit incremental-sigma modulator shown in an exemplary embodiment of the present application;

[0024] Figure 4This is a schematic diagram of the structure of a radio frequency front end shown in an exemplary embodiment of the present application;

[0025] Figure 5 This is a flowchart of Example 1 of a fully digital beamforming transmission method based on digital radio frequency technology provided in this application. DETAILED DESCRIPTION

[0026] Here, exemplary embodiments will be described in detail, and examples thereof are shown in the accompanying drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The implementations described in the following exemplary embodiments do not represent all implementations consistent with the present application.

[0027] The terms used in this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The singular forms of "a", "said" and "the" used in this application are also intended to include plural forms, unless the context clearly indicates other meanings. It should also be understood that the term "and / or" used in this article refers to and includes any or all possible combinations of one or more associated listed items.

[0028] It should be understood that although the terms first, second, third, etc. may be used in the present application to describe various information, these information should not be limited to these terms. These terms are only used to distinguish the same type of information from each other. For example, without departing from the scope of the present application, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Depending on the context, the word "if" as used herein may be interpreted as "at the time of" or "when" or "in response to determining".

[0029] Specific embodiments are given below to introduce the technical solution of the present application in detail.

[0030] Figure 1 This is a structural diagram of the first embodiment of the all-digital beamforming transmitter based on digital radio frequency technology provided by this application. Figure 1 The all-digital beamforming transmitter provided in this embodiment includes a plurality of baseband signal generators, orthogonal modulators, adders, 1-bit incremental integral modulators, digital-to-analog converters, radio frequency front ends, and antennas connected in sequence; wherein,

[0031] Each baseband signal generator is connected to an orthogonal modulator and an antenna, wherein the orthogonal modulator includes a plurality of orthogonal modulators, and each baseband signal generator generates a pair of baseband signals;

[0032] The number of the orthogonal modulators in the one-way orthogonal modulator is the same as the number of the adders, the number of the 1-bit incremental integral modulators, the number of the digital-to-analog converters, the number of the radio frequency front ends, and the number of the antennas; the number of the baseband signal generators is the same as the number of beams formed by the antennas, and the number of the baseband signal generators is different from the number of the orthogonal modulators in the one-way orthogonal modulator;

[0033] The adder is used to aggregate multiple modulated baseband signals in the same direction obtained after being processed by different orthogonal modulators to obtain an aggregated composite signal; the number of the composite signals is the same as the number of the adders;

[0034] The 1-bit delta-sigma modulator is used to convert the multiple composite signals obtained after being processed by the adder into a 1-bit digital signal.

[0035] For details, please refer to Figure 1 The all-digital beamforming transmitter includes a baseband signal generator, an orthogonal modulator, an adder, a 1-bit incremental integral modulator, a digital-to-analog converter, a radio frequency front end, and an antenna. In each branch, each baseband signal generator is connected to multiple orthogonal modulators, multiple orthogonal modulators are connected to each adder, each adder is connected to each 1-bit incremental integral modulator, each 1-bit incremental integral modulator is connected to each digital-to-analog converter, each digital-to-analog converter is connected to each radio frequency front end, and each radio frequency front end is connected to each antenna.

[0036] It should be noted that, in each branch, the number of orthogonal modulators is the same as the number of adders, the number of 1-bit delta-sigma modulators, the number of digital-to-analog converters, the number of RF front ends, and the number of antennas, which are all M. In each branch, the number of baseband signal generators is the same as the number of beams formed by the antennas, which are all N. In each branch, the number of baseband signal generators is N, and the number of orthogonal modulators is M. The number of baseband signal generators is different from the number of orthogonal modulators. In all branches, the total number of orthogonal modulators is M×N.

[0037] The beam forming process for each branch will be introduced below.

[0038] Specifically, the baseband signal generator is used to generate various types of baseband signals. The baseband signal refers to the original data or original signal that has not been modulated. It is usually a digital signal or an analog signal, which directly represents the information that needs to be transmitted in the communication system (such as audio, video or sensor data, etc.). Each baseband signal generator generates a pair of baseband signals, such as Figure 1 As shown, a pair of baseband signals includes an I-path signal and a Q-path signal, wherein the I-path signal represents the amplitude of the baseband signal, and the Q-path signal represents the phase of the baseband signal.

[0039] Further, after the baseband signal generated by the baseband signal generator is modulated by the orthogonal modulator to obtain multiple modulated baseband signals, the adder of each channel aggregates multiple modulated baseband signals in the same direction to form a composite signal (for example, please continue to refer to Figure 1 , adder #1 aggregates the modulated baseband signals Φ11, Φ21, ..., ΦN1 obtained by the orthogonal modulators on different branches, adder #2 aggregates the modulated baseband signals Φ12, Φ22, ..., ΦN2 obtained by the orthogonal modulators on different branches, and adder #M aggregates the modulated baseband signals Φ1M, Φ2M, ..., ΦNM obtained by the orthogonal modulators on different branches). The aggregation process is usually to linearly superimpose the baseband signals. Since these baseband signals may have different offsets at different frequencies or times, or they may represent synthetic signals from multiple data streams, in some cases, the adder may also involve time domain, frequency domain or spatial multiplexing of the baseband signals to improve transmission efficiency or increase the transmission distance of the baseband signals.

[0040] It should be noted that the number of composite signals finally obtained by the adders after aggregation is the same as the number of adders, which is M.

[0041] Specifically, after the adder aggregates multiple composite signals, each composite signal is transmitted to the corresponding 1-bit incremental integral modulator (for example, adder #1 transmits the composite signal obtained after aggregation to 1-bit incremental integral modulator #1, adder #2 transmits the composite signal obtained after aggregation to 1-bit incremental integral modulator #2, and adder #M transmits the composite signal obtained after aggregation to 1-bit incremental integral modulator #M). The 1-bit incremental integral modulator converts each received composite signal into a 1-bit digital signal.

[0042] The all-digital beamforming transmitter provided in this embodiment converts the composite signal into a 1-bit digital signal through a 1-bit incremental integral modulator. Since a 1-bit digital signal has only two states (0 and 1), it usually has a higher sampling frequency, higher precision, and is highly close to the input composite signal, reducing the processing complexity and hardware requirements for subsequent digital signal processing. In addition, the 1-bit incremental integral modulator effectively controls the noise in the conversion process through high-frequency sampling and noise shaping technology, and pushes the noise to the high-frequency region, thereby improving the quality of the low-frequency signal.

[0043] Optionally, each orthogonal modulator receives a pair of baseband signals generated by a baseband signal generator, performs frequency conversion on an I-path signal and a Q-path signal in the baseband signal respectively through a carrier signal generated by a digital processor, up-converts the I-path signal and the Q-path signal to an intermediate frequency or a radio frequency, synthesizes the up-converted I-path signal and the Q-path signal, and obtains a modulated baseband signal; the number of the modulated baseband signals is the same as the number of orthogonal modulators in each orthogonal modulator.

[0044] Specifically, each orthogonal modulator receives a pair of baseband signals (I-channel signal and Q-channel signal) generated by the baseband signal generator under the branch. The digital processor in each orthogonal modulator under the branch generates a carrier signal (usually a high-frequency signal, intermediate frequency or radio frequency), and performs frequency conversion on the I-channel signal and the Q-channel signal through the generated carrier signal. During the orthogonal modulation process, the up-conversion results of the I-channel signal and the Q-channel signal will be combined together to form a composite signal, that is, the modulated baseband signal.

[0045] It should be noted that each orthogonal modulator in each orthogonal modulator modulates the baseband signal to obtain a modulated baseband signal, and the number of modulated baseband signals finally obtained is the same as the number of orthogonal modulators, which is M. The process of modulating the baseband signal by each orthogonal modulator is basically the same, but since the phase of the carrier signal generated during modulation may be different, the final modulated baseband signal is different.

[0046] Optional, Figure 2 This is a schematic diagram of the structure of an orthogonal modulator shown in an exemplary embodiment of the present application. Figure 2 The orthogonal modulator includes a local oscillator, a multiplier and an adder connected in sequence; wherein the local oscillator is used to generate a carrier signal of a fixed frequency, including a cosine signal and a sine signal; the multiplier is used to multiply the baseband signal with the carrier signal, wherein the I-path signal is multiplied with the cosine signal, and the Q-path signal is multiplied with the sine signal, and outputs the I-path signal and the Q-path signal after up-conversion; the adder is used to add the I-path signal and the Q-path signal after up-conversion to obtain a modulated baseband signal.

[0047] For details, please refer to Figure 2, the orthogonal modulator includes a local oscillator, a multiplier and an adder. Among them, the local oscillator is connected to the multiplier, and the multiplier is connected to the adder. The local oscillator is responsible for generating a fixed frequency carrier signal, which is usually a continuous sine wave signal. The carrier signal includes a cosine signal and a sine signal. The cosine signal is used to modulate the I signal, and the sine signal is used to modulate the Q signal. The cosine signal and the sine signal have the same frequency but different phases. The two are orthogonal (i.e., a 90° phase difference), which facilitates the transmission of two independent information streams in the same frequency band. The multiplier is responsible for multiplying the baseband signal with the corresponding carrier signal, that is, multiplying the I-channel signal in the baseband signal with the cosine signal in the carrier signal, and moving the frequency of the I-channel signal from the baseband frequency to the carrier frequency; multiplying the Q-channel signal in the baseband signal with the sine signal in the carrier signal, and moving the frequency of the Q-channel signal from the baseband frequency to the carrier frequency. After being processed by the multiplier, both the I-channel signal and the Q-channel signal are up-converted to the radio frequency or intermediate frequency, and the phase relationship between them remains orthogonal. The adder is responsible for adding the up-converted I-channel signal and the Q-channel signal. After being processed by the adder, the I-channel signal and the Q-channel signal are synthesized into a composite signal. The synthesized signal contains two different information streams, which are carried by the I-channel and the Q-channel respectively.

[0048] Combined with the above description, the process of modulating the baseband signal by each orthogonal modulator is basically the same, but because the phase of the carrier signal generated during modulation may be different, the final modulated baseband signal is different. Optionally, different orthogonal modulators in one orthogonal modulator perform the same up-conversion processing on the baseband signal, and the local oscillator in each orthogonal modulator generates a carrier signal of the same frequency; by phase shifting the local oscillators in different orthogonal modulators in one orthogonal modulator, the phases of the carrier signals generated by the local oscillators in different orthogonal modulators are different, and the phases and amplitudes of the modulated baseband signals obtained in the end are different.

[0049] Specifically, each quadrature modulator performs up-conversion processing on the baseband signal, and converts the I-channel signal and the Q-channel signal in the baseband signal into a radio frequency signal. Since the carrier signal frequency generated by the local oscillator in each quadrature modulator is the same, that is, all quadrature modulators use the same frequency carrier for modulation. By phase shifting the local oscillators in different quadrature modulators, the carrier signal in each quadrature modulator will have a different phase. In other words, although the carrier frequencies of all quadrature modulators are the same, their phases can be adjusted (for example, by adjusting the phase of the oscillator). By changing the initial phase of the local oscillator, each quadrature modulator can generate a carrier signal with a different phase. For example, the carrier signal of the first quadrature modulator can be a cosine wave, the second can be a phase shift of the cosine wave, and the third can be a sine wave. The phase and amplitude of the modulated baseband signal will change according to the phase difference of the local oscillator in each quadrature modulator, and the beam direction finally generated will also change accordingly according to the phase difference of the local oscillator. By phase shifting the carrier signal, the modulated signal finally obtained will be different in phase. Although the amplitude is not directly affected by the phase adjustment, the modulated signal may exhibit different interference effects or phase superposition through different phase combinations, thus affecting the phase distribution of the final signal.

[0050] Optionally, the phase of each orthogonal modulator is achieved by adjusting the phase of a local oscillator. The carrier signals generated by the local oscillator in each orthogonal modulator have the same frequency, and the modulated baseband signals generated by each orthogonal modulator have different phases by performing phase shifting on the phase of the carrier signal. The phase of the carrier signal generated by the local oscillator in each orthogonal modulator is equal to the sum of a reference phase and a phase offset, wherein the reference phase is a fixed value, and the phase offset is adjusted by a digital phase shifter according to beamforming requirements.

[0051] The all-digital beamforming transmitter provided in this embodiment is implemented under the joint action of a baseband signal generator, multiple orthogonal modulators, an adder, a 1-bit incremental integral modulator, a digital-to-analog converter, an RF front end, and an antenna during the transmission process of each beam. The baseband signal is up-converted in the digital domain by an orthogonal modulator to convert the baseband signal into an RF signal. Compared with the previous use of an up-converter to realize the up-conversion of the baseband signal in the analog domain, an independent up-converter is not required, which simplifies the RF front end in the analog domain and realizes the miniaturization and low cost of the RF front end. On the one hand, the digital domain implementation allows more functions to be integrated in the same chip or module, greatly simplifying the design and integration of the system. In the analog domain implementation, multiple dedicated hardware components (such as local oscillators, mixers, filters, etc.) are usually required to achieve the same function, which makes the system larger in size, high in power consumption, and difficult to achieve high integration. In addition, the implementation of the digital domain reduces the demand for high-performance RF components (such as mixers, oscillators, filters, etc.), which are usually costly and difficult to control accurately, especially when processing high-frequency signals. Their performance stability is poor and they are easily affected by environmental changes. Secondly, the digital domain can perform precise time and frequency domain operations, which can achieve high-precision frequency synthesis and modulation and reduce signal errors. Digital signal processing makes the control of carrier signal frequency very precise. Through digital algorithms, parameters such as carrier frequency, phase and amplitude can be accurately adjusted. In the analog domain, the use of traditional analog oscillators and mixers for frequency synthesis is usually affected by factors such as temperature, aging, and component accuracy, resulting in drift of carrier signal frequency and phase, which is difficult to accurately control.

[0052] Optional, Figure 3 This is a schematic diagram of the structure of a 1-bit incremental integral modulator shown in an exemplary embodiment of the present application. Figure 3 The 1-bit delta-sigma modulator includes a digital loop filter and a 1-bit quantizer connected to each other; wherein the digital loop filter adjusts the frequency spectrum of each aggregated composite signal obtained by the adder, pushes the quantization noise in the composite signal to the high frequency region, and reduces the quantization noise in the composite signal; the 1-bit quantizer quantizes the composite signal processed by the digital loop filter, and converts the input composite signal into a 1-bit digital signal.

[0053] For details, please refer to Figure 3, the 1-bit incremental integral modulator includes a digital loop filter and a 1-bit quantizer, which are connected to each other. Among them, the digital loop filter is used to adjust the spectrum of the composite signal, push the quantization noise to a higher spectrum area, and reduce the influence of the quantization noise in the baseband frequency range. The digital loop filter appropriately processes the composite signal so that the low-frequency part (the effective part of the composite signal) is retained, and the quantization noise is moved to a higher frequency band, thereby avoiding noise interference with the low-frequency part of the signal and improving the signal-to-noise ratio of the system. The 1-bit quantizer is used to quantize the composite signal processed by the digital loop filter into a 1-bit digital signal, that is, only two discrete values ​​0 and 1 are used to represent the amplitude of the signal. By quantizing the composite signal into a 1-bit digital signal, the distortion caused by quantization can be greatly reduced.

[0054] In specific implementation, the composite signal aggregated by the adder is input into the digital loop filter, which may include quantization noise and useful signals. The digital loop filter adjusts the spectrum of the composite signal and pushes the quantization noise to the high-frequency area through noise shaping, thereby preventing the quantization noise from affecting the low-frequency part (useful signals). The processed composite signal enters the 1-bit quantizer, which quantizes the analog signal into a digital signal with only 0 and 1.

[0055] Optionally, the digital loop filter adjusts the frequency spectrum of each aggregated composite signal obtained by the adder, including: performing frequency response analysis on the composite signal to determine the frequency band of the composite signal to be optimized; based on the frequency band to be optimized, adjusting the zeros and poles of the digital loop filter to control the frequency spectrum distribution of quantization noise in the composite signal; the zeros and poles include zero points and poles, the output frequency of the digital loop filter is 0 at the zero point, and the output frequency of the digital loop filter tends to infinity at the pole point.

[0056] Specifically, the zero point of the digital loop filter is the frequency that makes the output signal zero in the frequency response. Adjusting the position of the zero point can change the attenuation and enhancement of a specific frequency band of the signal. The pole of the digital loop filter is the frequency at which the output signal of the digital loop filter tends to infinity. The configuration of the pole determines the direction in which the noise is pushed and the intensity of the noise. By adjusting the position of the zero pole, the digital loop filter can accurately control the spectral distribution of the quantization noise.

[0057] In specific implementation, Fourier transform is performed on the composite signal to determine the spectrum of the composite signal in the frequency domain. The spectrum is analyzed to determine the main frequency band of the noise and the main frequency band of the signal. According to the distribution of the main frequency band of the noise, the zero point of the digital loop filter is set within the main frequency band of the noise. According to the distribution of the main frequency band of the signal, the pole of the digital loop filter is set within the main frequency band of the signal.

[0058] In the specific implementation, the frequency response analysis of the composite signal is performed to evaluate the spectral characteristics of the composite signal, especially the distribution of quantization noise, and determine the frequency band that needs to be optimized (usually when the quantization noise has a greater impact on the low-frequency part). Since the quantization noise is usually distributed over the entire signal spectrum, through appropriate frequency response analysis, it is possible to identify which frequency bands need to be further optimized or suppressed. By analyzing the various frequency bands in the composite signal, the low-frequency signal area (i.e., the effective information part of the signal) and the high-frequency noise area (i.e., the quantization noise) are identified. Furthermore, based on the distribution of the identified quantization noise, the position of the zero pole is adjusted, wherein adjusting the zero point can weaken the signal in certain frequency bands, and adjusting the pole can enhance the high-frequency part of the noise. By adjusting the zero pole of the digital loop filter, the quantization noise is pushed to the high-frequency area to reduce the impact of low-frequency noise.

[0059] The all-digital beamforming transmitter provided in this embodiment filters and quantizes the aggregated composite signal through a 1-bit incremental integral modulator to obtain a 1-bit digital signal. Through noise shaping and high-frequency quantization, the 1-bit incremental integral modulator can provide higher resolution. By pushing the quantization noise to the high-frequency region, the 1-bit incremental integral modulator reduces the noise interference of the low-frequency part, thereby improving the quality of the digital signal and the signal-to-noise ratio of the system. By adjusting the zero poles of the digital loop filter in the digital domain, flexible adaptability can be provided for communication systems of different frequency bands to meet various communication needs. With the rapid development of wireless communication technology, new communication systems are constantly emerging, and they usually operate in different frequency bands. The signal characteristics and noise performance of different frequency bands are also different. Adjusting the zero poles of the digital loop filter enables the filter to be dynamically optimized according to the frequency band and noise distribution, thereby achieving adaptability to various communication systems. This adjustment can not only optimize the quality of the signal, but also effectively suppress noise, thereby improving the overall performance of the system. In practical applications, the zero poles of the digital loop filter can be configured according to the requirements of the communication system and the characteristics of the frequency band. Compared with analog filters, adjustments in the digital domain have greater flexibility. According to the spectrum analysis results and real-time signal feedback, the positions of zeros and poles can be quickly changed to achieve dynamic adaptation to different communication standards and frequency bands. In addition, the 1-bit quantizer is simple to implement. Compared with multi-bit quantizers, the 1-bit quantizer is more efficient in hardware, reducing the required circuit complexity and power consumption.

[0060] Optionally, the digital-to-analog converter is used to convert the 1-bit digital signal into a radio frequency signal, and transmit the radio frequency signal to a radio frequency front end.

[0061] Specifically, the digital-to-analog converter receives a 1-bit digital signal output by a 1-bit incremental-sigma modulator, and converts the 1-bit digital signal into a continuous analog signal (radio frequency signal) by means of amplitude modulation or pulse modulation.

[0062] Optional, Figure 4 This is a schematic diagram of the structure of a radio frequency front end shown in an exemplary embodiment of the present application. Figure 4 The RF front end includes a filter and an amplifier connected to each other; the filter and the amplifier of each RF front end are the same; wherein the filter is used to remove components in the RF signal that are higher or lower than the target frequency band, so as to obtain a RF signal that only retains the target frequency band; the amplifier performs power amplification on the RF signal processed by the filter based on the transmission requirements of the antenna, so as to obtain an amplified RF signal.

[0063] For details, please refer to Figure 4 , the RF front end is responsible for receiving and processing RF signals to ensure that the RF signals can meet the requirements of transmission or reception. The RF front end includes filters and amplifiers, which are connected to each other. Among them, the filter is responsible for removing unnecessary frequency components in the RF signal and only retaining the signal within the target frequency band. The amplifier is responsible for amplifying the power of the RF signal after filtering by the filter to meet the antenna transmission requirements. Since the strength of the RF signal usually attenuates as the transmission distance increases, it needs to be amplified before sending to ensure that the RF signal can cover a longer range.

[0064] It should be noted that the filters and amplifiers of each RF front end are the same, which can ensure that the gain and filtering characteristics of each RF link are consistent, help maintain the uniformity of the RF signal, and avoid interference, distortion or uneven signal quality caused by differences in each RF front end.

[0065] Optionally, the antenna receives the RF signal after filtering and amplification by the RF front end, converts the RF signal into electromagnetic waves and radiates them into free space, while forming multiple beams in different directions; each beam corresponds to a pair of baseband signals generated by a baseband signal generator.

[0066] Specifically, the number of beams formed by the antenna is the same as the number of baseband signal generators, which is N. Each beam corresponds to a pair of baseband signals generated by a baseband signal generator. Moreover, each beam is generated simultaneously and points to different directions.

[0067] In specific implementation, each antenna simultaneously receives the amplified RF signal sent by the RF front end on the branch, converts the RF signal into electromagnetic waves, determines the emission direction of the electromagnetic waves based on the phase and amplitude of the RF signal, and simultaneously emits electromagnetic waves in the emission direction of free space.

[0068] The all-digital beamforming transmitter based on digital radio frequency technology provided in this embodiment, on the one hand, in the all-digital beamforming transmitter provided in this application, the baseband signal processing, modulation, quantization and other operations are all completed by a digital processor, reducing the dependence on analog circuits. Digital signal processing can realize complex signal modulation and processing tasks on relatively simple hardware, reduce system complexity, and the transmitter architecture is simple and easy to integrate, and large-scale arraying is utilized. However, traditional radio frequency systems usually rely on a large number of analog circuits for frequency up-conversion, gain control, filtering, modulation, etc. These analog circuits often require precise design and debugging, which increases the complexity and manufacturing cost of the system. In addition, analog circuits are more sensitive to environmental changes (such as temperature, voltage fluctuations, etc.) and are prone to errors. In addition, the present application completes frequency conversion in the digital domain, simplifies the radio frequency front end, realizes the miniaturization and low cost of the radio frequency front end, and provides a basis for large-scale array formation. By transferring the up-conversion process to the digital domain, the transmitter no longer relies on traditional radio frequency components such as mixers, filters and amplifiers, which significantly reduces the complexity of the radio frequency front end and reduces the demand for high-precision radio frequency components, thereby simplifying the design of the entire transmitter. Since the modulation and beamforming of the RF signal are both performed in the digital domain, the RF front end only needs to include relatively simple hardware such as a digital-to-analog converter, which reduces the number and volume of RF hardware and reduces hardware costs. On the other hand, traditional RF systems rely on analog circuits to implement, and the signal processing accuracy of analog circuits is usually limited by device characteristics and environmental conditions (such as temperature, aging, etc.), and may cause large signal distortion and noise. However, the present application can achieve higher accuracy through digital signal processing and has strong anti-interference ability. The 1-bit incremental integral modulator and other digital filters can accurately control the noise distribution and signal quality, thereby improving the overall performance of the system. On the third hand, the aggregated composite signal is filtered and quantized by a 1-bit incremental integral modulator to obtain a 1-bit digital signal. Through noise shaping and high-frequency quantization, the 1-bit incremental integral modulator can provide higher resolution. By pushing the quantization noise to the high-frequency region, the 1-bit incremental integral modulator reduces the noise interference of the low-frequency part, thereby improving the quality of the digital signal and the signal-to-noise ratio of the system. By adjusting the zero poles of the digital loop filter in the digital domain, flexible adaptability can be provided for communication formats in different frequency bands to meet various communication needs. With the rapid development of wireless communication technology, new communication formats continue to emerge, and they usually operate in different frequency bands. The signal characteristics and noise performance of different frequency bands are also different. Adjusting the zero poles of the digital loop filter enables the filter to be dynamically optimized according to the frequency band and noise distribution, thereby achieving adaptability to various communication formats. This adjustment can not only optimize the signal quality, but also effectively suppress noise, thereby improving the overall performance of the system.In practical applications, the zero poles of the digital loop filter can be configured according to the requirements of the communication standard and the characteristics of the frequency band. Compared with analog filters, the adjustment in the digital domain has greater flexibility. According to the spectrum analysis results and real-time signal feedback, the position of the zero poles can be quickly changed to achieve dynamic adaptation to different communication standards and frequency bands. In addition, the implementation of the 1-bit quantizer is simple. Compared with the multi-bit quantizer, the 1-bit quantizer is more efficient in hardware, reducing the required circuit complexity and power consumption. Fourthly, the baseband signal is up-converted in the digital domain through the orthogonal modulator, and the baseband signal is converted into a radio frequency signal. Compared with the previous use of up-converters to achieve up-conversion of baseband signals in the analog domain, no independent up-converter is required, which simplifies the RF front end in the analog domain and realizes the miniaturization and low cost of the RF front end. In addition, the digital domain implementation allows more functions to be integrated in the same chip or module, greatly simplifying the design and integration of the system. In the analog domain, multiple dedicated hardware components (such as local oscillators, mixers, filters, etc.) are usually required to achieve the same function, which makes the system larger, power consumption higher, and difficult to achieve high integration. In addition, the implementation of the digital domain reduces the demand for high-performance RF components (such as mixers, oscillators, filters, etc.), which are usually costly and difficult to accurately control, especially when processing high-frequency signals, their performance stability is poor and easily affected by environmental changes. Fifthly, the digital domain can perform precise time domain and frequency domain operations, can achieve high-precision frequency synthesis and modulation, and reduce signal errors. Digital signal processing makes the control of carrier signal frequency very precise. Through digital algorithms, parameters such as carrier frequency, phase and amplitude can be accurately adjusted. In the analog domain, the use of traditional analog oscillators and mixers for frequency synthesis is usually affected by factors such as temperature, aging, and component accuracy, resulting in drift of carrier signal frequency and phase, which is difficult to accurately control.

[0069] Corresponding to the aforementioned embodiment of a fully digital beamforming transmitter based on digital radio frequency technology, the present application also provides an embodiment of a fully digital beamforming transmission method based on digital radio frequency technology.

[0070] Figure 5 This is a flowchart of the first embodiment of the all-digital beamforming transmission method based on digital radio frequency technology provided by this application. Please refer to Figure 5 The method provided in this embodiment is applied to the all-digital beamforming transmitter provided in any one of the first aspects of the present application, and the method includes:

[0071] S501. Each baseband signal generator generates a pair of baseband signals, and transmits the baseband signals to each corresponding orthogonal modulator.

[0072] S502: Each of the orthogonal modulators up-converts the baseband signal to an intermediate frequency or a radio frequency, and transmits the obtained modulated baseband signal to an adder.

[0073] S503, the adder aggregates multiple modulated baseband signals in the same direction obtained after being processed by different orthogonal modulators, and transmits the obtained aggregated composite signal to a 1-bit delta-sigma modulator.

[0074] S504. The 1-bit delta-sigma modulator converts the plurality of composite signals into a 1-bit digital signal, and transmits the digital signal to a digital-to-analog converter.

[0075] S505: The digital-to-analog converter converts the digital signal into a radio frequency signal, and transmits the radio frequency signal to a radio frequency front end.

[0076] S506: The RF front end performs filtering and amplification processing on the RF signal, and transmits the processed RF signal to the corresponding antenna.

[0077] S507. The antenna converts the processed radio frequency signal into electromagnetic waves and radiates them into free space to form a plurality of beams in different directions; each beam corresponds to a pair of baseband signals generated by a baseband signal generator.

[0078] The method of this embodiment can be used to execute Figure 1 The steps, specific implementation principles and implementation processes of the illustrated all-digital beamforming transmitter embodiment are similar and will not be repeated here.

[0079] The implementation process of the functions and effects of each unit in the above-mentioned device is specifically described in the implementation process of the corresponding steps in the above-mentioned method, and will not be repeated here.

[0080] For the device embodiment, since it basically corresponds to the method embodiment, the relevant parts can refer to the partial description of the method embodiment. The device embodiment described above is only schematic, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the present application scheme. A person of ordinary skill in the art can understand and implement it without paying any creative work.

[0081] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A fully digital beamforming transmitter based on digital radio frequency technology, characterized in that: The all-digital beamforming transmitter includes a plurality of baseband signal generators, orthogonal modulators, adders, 1-bit incremental integral modulators, digital-to-analog converters, radio frequency front ends and antennas connected in sequence; wherein, Each baseband signal generator is connected to an orthogonal modulator and an antenna, wherein the orthogonal modulator includes a plurality of orthogonal modulators, and each baseband signal generator generates a pair of baseband signals; The number of the orthogonal modulators in the one-way orthogonal modulator is the same as the number of the adders, the number of the 1-bit incremental integral modulators, the number of the digital-to-analog converters, the number of the radio frequency front ends, and the number of the antennas; the number of the baseband signal generators is the same as the number of beams formed by the antennas, and the number of the baseband signal generators is different from the number of the orthogonal modulators in the one-way orthogonal modulator; The adder is used to aggregate multiple modulated baseband signals in the same direction obtained after being processed by different orthogonal modulators to obtain an aggregated composite signal; the number of the composite signals is the same as the number of the adders; The 1-bit delta-sigma modulator is used to convert the multiple composite signals obtained after being processed by the adder into a 1-bit digital signal.

2. The all-digital beamforming transmitter according to claim 1, characterized in that: Each orthogonal modulator receives a pair of baseband signals generated by a baseband signal generator, performs frequency conversion on an I-channel signal and a Q-channel signal in the baseband signal respectively through a carrier signal generated by a digital processor, up-converts the I-channel signal and the Q-channel signal to an intermediate frequency or a radio frequency, synthesizes the up-converted I-channel signal and the Q-channel signal, and obtains a modulated baseband signal; The number of the modulated baseband signals is the same as the number of orthogonal modulators in each orthogonal modulator.

3. The all-digital beamforming transmitter according to claim 2, characterized in that: The orthogonal modulator comprises a local oscillator, a multiplier and an adder connected in sequence; wherein, The local oscillator is used to generate a carrier signal of a fixed frequency, including a cosine signal and a sine signal; The multiplier is used to multiply the baseband signal with the carrier signal, wherein the I-channel signal is multiplied with the cosine signal, and the Q-channel signal is multiplied with the sine signal, and outputs the I-channel signal and the Q-channel signal after up-conversion; The adder is used to add the up-converted I-path signal and Q-path signal to obtain a modulated baseband signal.

4. The all-digital beamforming transmitter according to claim 3, characterized in that: Different orthogonal modulators in one orthogonal modulator perform the same up-conversion processing on the baseband signal, and the local oscillator in each orthogonal modulator generates a carrier signal with the same frequency; By shifting the phase of the local oscillators in different orthogonal modulators in one orthogonal modulator, the phases of the carrier signals generated by the local oscillators in different orthogonal modulators are different, and the phases and amplitudes of the modulated baseband signals finally obtained are different.

5. The all-digital beamforming transmitter according to claim 1, characterized in that: The 1-bit delta-sigma modulator comprises a digital loop filter and a 1-bit quantizer connected to each other; wherein, The digital loop filter adjusts the frequency spectrum of each aggregated composite signal obtained by the adder, pushes the quantization noise in the composite signal to a high frequency region, and reduces the quantization noise in the composite signal; The 1-bit quantizer quantizes the composite signal processed by the digital loop filter, and converts the input composite signal into a 1-bit digital signal.

6. The all-digital beamforming transmitter according to claim 5, characterized in that: The digital loop filter adjusts the spectrum of each aggregated composite signal obtained by the adder, including: Performing frequency response analysis on the composite signal to determine a frequency band of the composite signal to be optimized; Based on the frequency band to be optimized, the zero poles of the digital loop filter are adjusted to control the frequency spectrum distribution of the quantization noise in the composite signal; the zero poles include zero points and poles, the output frequency of the digital loop filter is 0 at the zero point, and the output frequency of the digital loop filter tends to infinity at the pole point.

7. The all-digital beamforming transmitter according to claim 1, characterized in that: The digital-to-analog converter is used to convert the 1-bit digital signal into a radio frequency signal and transmit the radio frequency signal to a radio frequency front end.

8. The all-digital beamforming transmitter according to claim 7, characterized in that: The RF front end includes a filter and an amplifier connected to each other; the filter and amplifier of each RF front end are the same; wherein, The filter is used to remove components in the radio frequency signal that are higher or lower than the target frequency band, so as to obtain a radio frequency signal that only retains the target frequency band; The amplifier performs power amplification on the radio frequency signal processed by the filter based on the transmission requirement of the antenna to obtain an amplified radio frequency signal.

9. The all-digital beamforming transmitter according to claim 8, characterized in that: The antenna receives the RF signal filtered and amplified by the RF front end, converts the RF signal into electromagnetic waves and radiates them into free space, while forming multiple beams in different directions; each beam corresponds to a pair of baseband signals generated by a baseband signal generator.

10. A fully digital beamforming transmission method based on digital radio frequency technology, characterized in that: The all-digital beamforming transmission method is applied to the all-digital beamforming transmitter according to any one of claims 1 to 9, and the method comprises: Each baseband signal generator generates a pair of baseband signals, and transmits the baseband signals to each corresponding orthogonal modulator; Each of the orthogonal modulators up-converts the baseband signal to an intermediate frequency or a radio frequency, and transmits the obtained modulated baseband signal to an adder; The adder aggregates a plurality of modulated baseband signals in the same direction obtained after being processed by different orthogonal modulators, and transmits the obtained aggregated composite signal to a 1-bit incremental integral modulator; The 1-bit delta-sigma modulator converts the plurality of composite signals into a 1-bit digital signal, and transmits the digital signal to a digital-to-analog converter; The digital-to-analog converter converts the digital signal into a radio frequency signal, and transmits the radio frequency signal to a radio frequency front end; The RF front end performs filtering and amplification processing on the RF signal, and transmits the processed RF signal to the corresponding antenna; The antenna converts the processed radio frequency signal into electromagnetic waves and radiates them into free space, forming a plurality of beams in different directions; each beam corresponds to a pair of baseband signals generated by a baseband signal generator.

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