Digital pre-distortion processing circuit and signal processing device

Abstract

The present application relates to a digital pre-distortion processing circuit and a signal processing device, the digital pre-distortion processing circuit comprising a narrow-band spread spectrum module, a digital pre-distortion module and a filtering module. The narrow-band spread spectrum module is used to spread the input narrow-band radio frequency signal into a wide-band radio frequency signal. The bandwidth of the wide-band radio frequency signal is a preset bandwidth. The digital pre-distortion module is used to perform digital pre-distortion linearization processing on the wide-band radio frequency signal to obtain a linearized wide-band radio frequency signal; the preset bandwidth is located within the optimal cancellation bandwidth of the digital pre-distortion module. The filtering module is used to perform signal filtering on the linearized wide-band radio frequency signal to obtain a linearized narrow-band radio frequency signal. The digital pre-distortion linearization processing on the narrow-band radio frequency signal is realized, and the cancellation capability of the digital pre-distortion system for the narrow-band radio frequency signal is greatly improved.

Description

Technical Field

[0001] This invention relates to the field of communication technology, and in particular to a digital predistortion processing circuit and signal processing device. Background Technology

[0002] With the rapid development of mobile communication technology, 4G and 5G communication systems have gradually become mainstream, leading to increasingly congested wireless communication frequency bands and higher peak-to-average power ratio (PAR). To accommodate more communication channels within a limited spectrum, transmission technologies with high spectral efficiency are required. However, due to the inherent nonlinearity of power amplifiers, they can interfere with other communication channels within the same frequency band, affecting spectral efficiency. Therefore, to address the issues of spectral efficiency and power amplifier nonlinearity, the industry commonly employs CFR peak clipping technology and power amplifier linearization technology.

[0003] Digital predistortion technology, particularly in power amplifier linearization, holds a significant position and plays a crucial role in modern wireless communication. However, during the development of this invention, the inventors discovered that traditional digital predistortion systems have poor cancellation capabilities for narrowband radio frequency signals. Summary of the Invention

[0004] Therefore, it is necessary to provide a digital predistortion processing circuit and a signal processing device to address the aforementioned problems of traditional digital predistortion systems.

[0005] To achieve the above objectives, the embodiments of the present invention adopt the following technical solutions:

[0006] On one hand, embodiments of the present invention provide a digital predistortion processing circuit, comprising:

[0007] A narrowband spread spectrum module is used to spread an input narrowband radio frequency signal into a wideband radio frequency signal; the bandwidth of the wideband radio frequency signal is a preset bandwidth.

[0008] The digital predistortion module is used to perform digital predistortion linearization processing on broadband radio frequency signals to obtain linearized broadband radio frequency signals; the preset bandwidth is located within the optimal cancellation bandwidth of the digital predistortion module;

[0009] The filtering module is used to filter the linearized broadband radio frequency signal to obtain the linearized narrowband radio frequency signal.

[0010] In one embodiment, the narrowband spread spectrum module includes a combiner and a spread spectrum signal source. The first input port of the combiner is used to receive narrowband radio frequency signals, and the second input port of the combiner is connected to the output of the spread spectrum signal source.

[0011] The spread spectrum signal source is used to output a broadband signal with a target bandwidth to the combiner after receiving the indication signal output by the main controller of the predistortion system. The combiner is used to combine the broadband signal with the narrowband radio frequency signal and output the resulting broadband radio frequency signal to the digital predistortion module.

[0012] In one embodiment, the narrowband spread spectrum module further includes a first coupler, a power detector, and a power attenuator;

[0013] The input port of the first coupler is used to receive narrowband radio frequency signals. The output port of the first coupler is connected to the first input port of the combiner. The coupling port of the first coupler is connected to the input port of the power detector. The input of the power attenuator is connected to the output of the spread spectrum signal source. The output of the power attenuator is connected to the second input port of the combiner.

[0014] The power detector is used to detect the signal power of the narrowband radio frequency signal and transmit it to the main controller. The power attenuator is used to attenuate the signal power of the broadband signal to less than that of the narrowband radio frequency signal after receiving the power adjustment signal output by the main controller.

[0015] In one embodiment, the narrowband spread spectrum module further includes a first radio frequency switch and a second radio frequency switch;

[0016] The moving contact of the first RF switch is used to access narrowband RF signals, the first stationary contact of the first RF switch is connected to the input port of the first coupler, and the second stationary contact of the first RF switch is connected to the first stationary contact of the second RF switch.

[0017] The second stationary contact of the second RF switch is connected to the combining port of the combiner, and the moving contact of the second RF switch is connected to the input port of the digital predistortion module.

[0018] In one embodiment, the filtering module is a filter, the input port of the filter is connected to the output port of the digital predistortion module, and the output port of the filter is used to output the linearized narrowband radio frequency signal.

[0019] In one embodiment, the digital predistortion processing circuit further includes a third radio frequency switch. The moving contact of the third radio frequency switch is connected to the output port of the digital predistortion module, the first stationary contact of the third radio frequency switch is connected to the input port of the filter, and the second stationary contact of the third radio frequency switch is used to output a broadband radio frequency signal that has not been spread and has been linearized.

[0020] In one embodiment, the digital predistortion module includes a frequency conversion module, a digital predistortion module, a digital-to-analog converter, a first mixer, an RF power amplifier, a second coupler, a second mixer, a first local oscillator, a first analog-to-digital converter, and an adaptive controller.

[0021] The frequency conversion module, digital predistortion module, digital-to-analog converter, first mixer, RF power amplifier and second coupler are connected in series. The input port of the frequency conversion module is connected to the output port of the narrowband spread spectrum module.

[0022] The output port of the second coupler is connected to the input port of the filter module, the coupling port of the second coupler is connected to the input port of the second mixer, the output port of the second mixer is connected to the first input port of the adaptive controller through the first analog-to-digital converter, the second input port of the adaptive controller is connected to the output port of the frequency conversion module, and the feedback output port of the adaptive controller is connected to the feedback input port of the digital predistortion module.

[0023] The output port of the first local oscillator is connected to the local oscillator input ports of the first mixer and the second mixer, respectively.

[0024] In one embodiment, the frequency conversion module includes a third mixer, a second local oscillator, a second analog-to-digital converter, and a digital down-converter;

[0025] The third mixer, the second analog-to-digital converter, and the digital down-converter are connected in series. The input port of the third mixer is connected to the output port of the narrowband spread spectrum module, and the local oscillator input port of the third mixer is connected to the output port of the second local oscillator. The output port of the digital down-converter is connected to the input port of the digital predistortion module and the second input port of the adaptive controller, respectively.

[0026] On the other hand, a signal processing device is also provided, including the aforementioned digital predistortion processing circuit.

[0027] In one embodiment, the signal processing device described above further includes a main controller, and the narrowband spread spectrum module of the digital predistortion processing circuit includes a spread spectrum signal source, a power detector, and a power attenuator.

[0028] The main controller is used to output an indication signal to the spread spectrum signal source, receive the signal power transmitted by the power detector, and output a power adjustment signal to the power attenuator.

[0029] In one embodiment, the digital predistortion processing circuit further includes a third radio frequency switch, and the narrowband spread spectrum module further includes a first radio frequency switch and a second radio frequency switch.

[0030] The main controller is electrically connected to the switch control terminals of the first RF switch, the second RF switch, and the third RF switch, respectively. The main controller is also used to output switch control signals to the first RF switch, the second RF switch, and the third RF switch, respectively.

[0031] In one embodiment, the signal processing device is any one of a base amplifier, a repeater, a radio frequency remote amplifier, a track power amplifier, an integrated power amplifier, and a receiver.

[0032] One of the above technical solutions has the following technical effects:

[0033] The aforementioned digital predistortion processing circuit and signal processing equipment, through the use of a narrowband spread spectrum module and a filtering module, and optimized circuit design with the digital predistortion module, enable the narrowband RF signal to be spread to a broadband RF signal with a bandwidth within the optimal cancellation bandwidth of the digital predistortion module when the input RF signal is narrowband. Furthermore, the digital predistortion module can effectively perform digital predistortion linearization processing on this broadband RF signal. Finally, by filtering the broadband RF signal after digital predistortion linearization, the spread spectrum component is removed, yielding the linearized narrowband RF signal. This achieves digital predistortion linearization processing of the narrowband RF signal, significantly improving the cancellation capability of the digital predistortion system for narrowband RF signals. Attached Figure Description

[0034] Figure 1 A waveform diagram illustrating the existing digital predistortion processing techniques;

[0035] Figure 2 A schematic diagram of the circuit structure of an existing digital predistortion processing system;

[0036] Figure 3 This is a schematic diagram of the first structure of a digital predistortion processing circuit in one embodiment;

[0037] Figure 4 This is a schematic diagram of the second structure of a digital predistortion processing circuit in one embodiment;

[0038] Figure 5 This is a schematic diagram of the third structure of a digital predistortion processing circuit in one embodiment;

[0039] Figure 6 This is a schematic diagram of the fourth structure of the digital predistortion processing circuit in one embodiment;

[0040] Figure 7 This is a schematic diagram of the fifth structure of the digital predistortion processing circuit in one embodiment;

[0041] Figure 8 This is a schematic diagram of the sixth structure of the digital predistortion processing circuit in one embodiment;

[0042] Figure 9 This is a schematic diagram of the seventh structure of a digital predistortion processing circuit in one embodiment;

[0043] Figure 10 This is a schematic diagram of the digital predistortion processing circuit structure of a signal processing device in one embodiment. Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0045] It should be noted that, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0046] Digital predistortion (DPD) is one of the most fundamental modules in modern wireless communication systems. By reducing the distortion generated by power amplifiers during their nonlinear operation, the efficiency of power amplifiers can be significantly improved. DPD technology can be applied to both the baseband and radio frequency (RF) sections of digital communication systems. Furthermore, DPD can automatically track and compensate for errors caused by changes in factors such as temperature and gate voltage using adaptive principles. Existing baseband digital domain signal processing algorithms in DPD technology offer high performance and excellent linearization effects, characterized by good linearization performance, flexible design, and strong applicability. When used in conjunction with Doherty power amplifiers, it maximizes the efficiency of the DPD system, thus gradually becoming the mainstream linearization technology and playing a crucial role in modern wireless communication.

[0047] like Figure 1 The diagram shows the waveform schematic of a digital predistortion system. When two symmetrical PA curves (i.e., power amplifier curves) are superimposed, a highly linear curve on the right side of the equation is obtained, corresponding to the linearized output curve after digital predistortion processing. Since the power amplifier operates in the nonlinear region, output compression will result in AM-AM and AM-PM distortion curves. The function of the DPD (Digital Predistortion Processing) is to output a curve in the opposite direction to AM-AM and AM-PM, thus achieving the predistortion effect. Based on the nonlinear characteristics of the power amplifier (amplitude and phase distortion), the input signal to the power amplifier is subjected to opposite distortion processing. The combination of these two nonlinear distortion functions achieves a highly linear and distortion-free system. Predistortion processing performed on the digital baseband is called digital predistortion, while predistortion processing performed on analog circuits is called analog predistortion. Figure 2As shown, the predistorter in a digital predistortion system processes the nonlinearity of the power amplifier (PA) in the digital domain. By generating a curve symmetrical to the PA curve through the predistorter and then superimposing it on the PA curve, the linearity of the output PA curve can be improved, thus canceling out nonlinearity. Figure 2 As shown by the curve to the right of the medium sign.

[0048] like Figure 2 The diagram shows the circuit structure of a commonly used digital predistortion linearization system in conventional digital predistortion linearization technology. Its working principle is as follows: The input RF signal is down-converted by a downconverter, then converted to a digital signal by an analog-to-digital converter (ADC), and finally converted back to a digital signal by a digital downconverter before entering the digital predistortion module, also known as the digital predistortion chip. Simultaneously, the output RF signal coupled from the RF output terminal is processed by the downconverter and ADC on the feedback side, converted into a corresponding digital signal, and enters the digital predistortion adaptive controller. The digital predistortion adaptive controller adaptively compares the output digital signal with the input digital signal, identifies the difference between the two signals, and adaptively calibrates the signal before sending it to the digital predistortion module. Finally, the digital predistortion module outputs a calibrated digital signal, which already includes the RF power amplifier (i.e.,...). Figure 2 The digital predistortion signal is used in the RF power amplifier (similar to the power amplifier mentioned above). Finally, this digital signal is processed by a digital-to-analog converter and an up-converter, and then input into the RF power amplifier for amplification and output, thereby improving the linearity of the RF power amplifier.

[0049] Existing digital predistortion systems have a certain operating bandwidth (i.e., cancellation bandwidth). During practical testing, the inventors discovered that a signal bandwidth that is too wide or too narrow affects the cancellation capability of the digital predistortion system. If a signal has a very narrow bandwidth, such as the currently used NB-IoT (Narrowband Internet of Things) signal with a bandwidth of only 180kHz, traditional digital predistortion systems will have poor cancellation capability for such narrowband signals. Based on this, this application provides the following technical solution to address this issue:

[0050] Please see Figure 3In one embodiment, a digital predistortion processing circuit 100 is provided, including a narrowband spread spectrum module 12, a digital predistortion module 14, and a filtering module 16. The narrowband spread spectrum module 12 is used to spread an input narrowband radio frequency (RF) signal into a wideband RF signal. The bandwidth of the wideband RF signal is a preset bandwidth. The digital predistortion module 14 is used to perform digital predistortion linearization processing on the wideband RF signal to obtain a linearized wideband RF signal. The preset bandwidth is located within the optimal cancellation bandwidth of the digital predistortion module 14. The filtering module 16 is used to filter the linearized wideband RF signal to obtain a linearized narrowband RF signal.

[0051] It is understood that the narrowband spread spectrum module 12 can be a circuit module or device with signal bandwidth expansion function in the art, such as a mixer, combiner, or a combination thereof, which can expand the bandwidth of the input signal to the required bandwidth according to the set signal bandwidth. The digital predistortion module 14 is a conventional digital predistorter (chip) in the art. The specific circuit structure of different models of digital predistortion modules 14 will be different, and they can provide predistortion linearization processing functions with different performance. The specific structure of the digital predistortion module 14 can be determined by the specific circuit structure of the digital predistorter selected according to the application requirements in the actual application. The filter module 16 is a filter or filter circuit module with a filter bandwidth corresponding to the spread spectrum bandwidth of the narrowband spread spectrum module 12, such as, but not limited to, a single or multiple filters, or a comprehensive filter circuit module with filtering and amplification functions.

[0052] Specifically, different digital predistortion modules 14 have different optimal cancellation bandwidths. If the bandwidth of the input RF signal is within the optimal cancellation bandwidth of the digital predistortion module 14, then the digital predistortion module 14 has good cancellation performance for that RF signal. However, in practical applications, there are often situations where the bandwidth of the input RF signal is extremely narrow. Therefore, in applications where the received input signal is a narrowband RF signal, the spreading parameters of the narrowband spreading module 12 can be set in advance according to the bandwidth of the narrowband RF signal. For example, the bandwidth of the signal generated autonomously by the narrowband spreading module 12 or received from an external signal source and used for spreading can be set to spread the input narrowband RF signal to a broadband RF signal with a preset bandwidth.

[0053] In practical applications, a signal bandwidth detection device can be set at the input of the narrowband spread spectrum module 12 to automatically detect the bandwidth of the input RF signal and report the detected bandwidth to the main controller of the device to which the digital predistortion processing circuit 100 is applied. The main controller then determines whether the current input RF signal is a wideband or narrowband RF signal. If it is a wideband RF signal (i.e., the signal bandwidth is already within the optimal cancellation bandwidth of the digital predistortion module 14), the main controller does not need to control the narrowband RF signal. The wideband RF signal does not need to pass through the narrowband spread spectrum module 12 but directly enters the digital predistortion module 14 for predistortion processing before being output. The output can be either directly without passing through the filter module 16 or after passing through the filter module 16. If it is a narrowband RF signal, the main controller can adjust the spreading parameters of the narrowband spread spectrum module 12 according to the preset spreading parameter table to spread the input narrowband RF signal to a wideband RF signal with a preset bandwidth. The spread spectrum parameter table stores the required spread spectrum bandwidth for narrowband radio frequency signals of different bandwidths. After receiving the control signal output by the main controller, the narrowband spread spectrum module 12 can spread the narrowband radio frequency signal according to the spread spectrum bandwidth.

[0054] The broadband RF signal obtained after spreading by the narrowband spread spectrum module 12 enters the digital predistortion module 14, where it undergoes digital predistortion linearization processing to obtain the linearized broadband RF signal output. Subsequently, the linearized broadband RF signal enters the filtering module 16 for filtering, removing the spreading components from the linearized broadband RF signal. This means filtering out the signal components superimposed on the narrowband RF signal when the narrowband spread spectrum module 12 spreads the input narrowband RF signal. After filtering by the filtering module 16, the output of the linearized broadband RF signal is the narrowband RF signal that has undergone effective digital predistortion linearization processing.

[0055] By employing a narrowband spread spectrum module 12 and a filter module 16, and optimizing the circuit design with the digital predistortion module 14, the input RF signal, being a narrowband RF signal, can be spread to a wideband RF signal with a bandwidth within the optimal cancellation bandwidth of the digital predistortion module 14. Furthermore, the digital predistortion module 14 can effectively perform digital predistortion linearization processing on the wideband RF signal. Finally, by filtering the linearized wideband RF signal and removing the spread spectrum component, the linearized narrowband RF signal is obtained. This achieves digital predistortion linearization processing of the narrowband RF signal, significantly improving the cancellation capability of the digital predistortion system, i.e., the digital predistortion processing circuit 100 based on the improved digital predistortion module 14, for narrowband RF signals.

[0056] Please see Figure 4 In one embodiment, the narrowband spread spectrum module 12 includes a combiner 122 and a spread spectrum signal source 124. A first input port of the combiner 122 is used to receive a narrowband radio frequency signal. A second input port of the combiner 122 is connected to the output of the spread spectrum signal source 124. The spread spectrum signal source 124, upon receiving an indication signal from the main controller of the predistortion system, outputs a broadband signal with a target bandwidth to the combiner 122. The combiner 122 combines the broadband signal with the narrowband radio frequency signal and outputs the resulting broadband radio frequency signal to the digital predistortion module 14.

[0057] It is understood that the spread spectrum signal source 124 is a conventional signal source in this field, capable of generating a signal with a corresponding bandwidth according to a pre-set signal bandwidth or by receiving a signal bandwidth control signal output from the main controller in real time. The target bandwidth refers to the signal bandwidth required to spread the input narrowband RF signal to the preset bandwidth. The bandwidth of the signal generated by the spread spectrum signal source 124 can be manually preset as the target bandwidth based on the bandwidth of the input narrowband RF signal and its spread spectrum requirements in the actual application scenario, or it can be automatically set by the main controller according to a pre-set spread spectrum parameter table. The main controller of the predistortion system refers to the main controller in the device where the digital predistortion processing circuit 100 is applied, which provides control functions for the digital predistortion processing process; it is typically the main control chip inherent in the applied device.

[0058] Specifically, in this embodiment, a combiner 122 and a spread spectrum signal source 124 are used to spread the input narrowband radio frequency signal. The input narrowband radio frequency signal enters the combiner 122 through its first input port. Simultaneously, the spread spectrum signal source 124 generates a broadband signal with a target bandwidth and outputs it to the combiner 122 through its second input port. The combiner 122 combines the input narrowband radio frequency signal and the broadband signal with the target bandwidth to spread the input narrowband radio frequency signal into a broadband radio frequency signal with a preset bandwidth. To more intuitively understand the aforementioned spread spectrum process, let's take an input narrowband RF signal with a frequency of 1842.5MHz and a bandwidth of 160kHz, and a wideband signal X1 generated by the spread spectrum signal source 124 with a bandwidth of 2MHz and a center frequency of 1844.5MHz as an example. The input narrowband RF signal Pin and the wideband signal X1 generated by the spread spectrum signal source 124 are combined in the combiner 122 to become a wideband signal (Pin+X1) with a preset bandwidth. This signal is then output to the digital predistortion module 14 for digital predistortion linearization processing. This allows for the linearization of the input narrowband RF signal Pin within the optimal cancellation bandwidth of the digital predistortion module 14. The preset bandwidth of the wideband RF signal can be less than or equal to the optimal cancellation bandwidth of the digital predistortion module 14; when it is equal, the cancellation effect is optimal.

[0059] By using the combiner 122 and the spread spectrum signal source 124 described above, the spread spectrum processing of the input narrowband radio frequency signal can be achieved efficiently and easily without the need to use the relatively complex spread spectrum technology in this field. The circuit structure is simple and more efficient.

[0060] Please see Figure 5 In one embodiment, the narrowband spread spectrum module 12 further includes a first coupler 126, a power detector 128, and a power attenuator 129. The input port of the first coupler 126 is used to receive narrowband radio frequency signals. The output port of the first coupler 126 is connected to the first input port of the combiner 122. The coupling port of the first coupler 126 is connected to the input port of the power detector 128. The input terminal of the power attenuator 129 is connected to the output terminal of the spread spectrum signal source 124. The output terminal of the power attenuator 129 is connected to the second input port of the combiner 122. The power detector 128 is used to detect the signal power of the narrowband radio frequency signal and transmit it to the main controller. The power attenuator 129, after receiving the power adjustment signal output by the main controller, attenuates the signal power of the transmitted broadband signal to a level lower than that of the narrowband radio frequency signal.

[0061] It is understood that the first coupler 126, power detector 128 and power attenuator 129 mentioned above are all conventional signal processing devices in the art. The specific types and models of each device can be selected according to the needs of spread spectrum processing of the input narrowband radio frequency signal and application costs in the actual application scenario.

[0062] Specifically, since the broadband signal superimposed on the input narrowband RF signal needs to be filtered out after processing and output by the digital predistortion module 14, and the power of the broadband signal with the target bandwidth is greater than the signal power of the input narrowband RF signal, the resulting broadband RF signal will have excessively high power. This increases the operating current of the digital predistortion module 14, leading to higher energy consumption. Furthermore, the input narrowband RF signal becomes a secondary signal relative to the broadband signal with the target bandwidth, and the processing effect of the digital predistortion module 14 on the narrowband RF signal component will also decrease. Therefore, it is necessary to control the power of the broadband signal with the target bandwidth to be less than the signal power of the input narrowband RF signal. In some practical applications, the power of the broadband signal is about 3dB lower than the signal power of the input narrowband RF signal, which can effectively avoid increasing the operating current of the digital predistortion module 14, and the processing effect of the digital predistortion module 14 on the narrowband RF signal component is not affected by the power level.

[0063] The input narrowband RF signal enters the combiner 122 via the first coupler 126. Simultaneously, a portion of the input narrowband RF signal is coupled out from the first coupler 126 and sent to the power detector 128. The power detector 128 obtains the signal power of the input narrowband RF signal and transmits it to the main controller. The main controller then controls the attenuation of the broadband signal output from the spread spectrum source 124 by the power attenuator 129 according to the signal power of the input narrowband RF signal, ensuring that the signal power of the broadband signal is less than that of the input narrowband RF signal. For example, if the signal power of the input narrowband RF signal is 0dB, the power attenuator 129 will attenuate the signal power of the broadband signal output from the spread spectrum source 124 to -3dB. The two signals are then combined and output in the combiner 122. Thus, through the application of the first coupler 126, the power detector 128, and the power attenuator 129, the signal power of the combined broadband RF signal is moderate, effectively reducing the power consumption of the digital predistortion module 14 and further improving the digital predistortion processing effect.

[0064] Please see Figure 6In one embodiment, the narrowband spread spectrum module 12 further includes a first RF switch 127 and a second RF switch 125. The moving contact of the first RF switch 127 is used to receive narrowband RF signals. The first stationary contact of the first RF switch 127 is connected to the input port of the first coupler 126. The second stationary contact of the first RF switch 127 is connected to the first stationary contact of the second RF switch 125. The second stationary contact of the second RF switch 125 is connected to the combining port of the combiner 122. The moving contact of the second RF switch 125 is connected to the input port of the digital predistortion module 14.

[0065] It is understood that in this embodiment, two RF switches can be used to select and switch the signal transmission path. The input RF signal enters the digital predistortion processing circuit 100 through the first RF switch 127. If the input RF signal is a wideband RF signal, that is, the digital predistortion processing circuit 100 operates in the normal digital predistortion processing mode, the input RF signal does not need to undergo spread spectrum processing and can directly enter the digital predistortion module 14 for processing and output. If the input RF signal is a narrowband RF signal, that is, the digital predistortion processing circuit 100 operates in the narrowband cancellation mode, the input RF signal needs to undergo spread spectrum processing before it can enter the digital predistortion module 14 for processing and output.

[0066] Specifically, in the ordinary digital predistortion processing mode, the moving contact of the first RF switch 127 closes with the second stationary contact, and the moving contact of the second RF switch 125 closes with the first stationary contact, thus forming a direct signal path that bypasses the first coupler 126 to the combiner 122. The input RF signal passes through the first RF switch 127 and the second RF switch 125 and directly enters the digital predistortion module 14 for conventional digital predistortion linearization processing. The circuit structure of the digital predistortion module 14 adopts the following... Figure 2 Taking the circuit structure of the digital predistortion line system shown as an example, the input RF signal passes through the first RF switch 127 and the second RF switch 125, and then enters the downconverter and analog-to-digital converter. After processing by the digital downconverter, the input RF signal is converted into a digital signal and enters the digital predistortion module and the digital predistortion adaptive controller. A portion of the output RF signal coupled from the coupler at the output port of the RF power amplifier is used as a feedback signal. After being processed by the downconverter and analog-to-digital converter in the feedback link, this feedback signal is also converted into a digital signal and sent to the digital predistortion adaptive controller.

[0067] The digital predistortion adaptive controller uses its built-in algorithm to compare the difference between the digital signal corresponding to the input RF signal and the digital signal corresponding to the feedback signal. It automatically tracks and calculates the predistortion signal of both signals and superimposes this predistortion signal onto the digital signal corresponding to the input RF signal through interaction with the digital predistortion module. Finally, the digital predistortion module outputs a predistortion-corrected digital signal. This predistortion-corrected digital signal is converted into the corresponding RF signal by a digital-to-analog converter and an up-converter, and then amplified and output by an RF power amplifier. The RF signal output from the RF power amplifier, i.e., the linearized RF signal, is also coupled through a coupler as a feedback signal. This allows the digital predistortion adaptive controller to determine the predistortion cancellation effect based on the feedback signal and continuously perform loop feedback to iteratively optimize the digital predistortion linearization processing effect.

[0068] In narrowband cancellation mode, the moving contact and the stationary contact of the first RF switch 127 are closed, and the moving contact and the stationary contact of the second RF switch 125 are closed, forming a signal spread spectrum path through the first coupler 126 to the combiner 122. The input RF signal, after passing through the first RF switch 127 and the first coupler 126, enters the combiner 122. Simultaneously, the first coupler 126 couples out a portion of the input RF signal to the power detector 128. The power detector 128 then obtains the signal power of the input narrowband RF signal and transmits it to the main controller. The main controller then controls the attenuation of the broadband signal output from the spread spectrum signal source 124 by the power attenuator 129, ensuring that the signal power of the broadband signal is less than the signal power of the input narrowband RF signal. Subsequently, the input RF signal and the broadband signal are combined and output in the combiner 122. The output broadband RF signal passes through the second RF switch 125 and enters the digital predistortion module 14 for digital predistortion linearization processing.

[0069] The closing action between the contacts of the first RF switch 127 and the second RF switch 125 can be achieved manually or automatically by the main controller according to the corresponding switch control logic under the preset working mode (i.e., ordinary digital predistortion processing mode or narrowband cancellation mode). Through the aforementioned settings of the first RF switch 127 and the second RF switch 125, the switching of signal paths corresponding to input RF signals of different bandwidths can be quickly realized to respectively achieve digital predistortion processing of the input broadband or narrowband RF signals.

[0070] In one embodiment, the filter module 16 is a filter, the input port of the filter is connected to the output port of the digital predistortion module 14, and the output port of the filter is used to output the linearized narrowband radio frequency signal.

[0071] It is understood that in this embodiment, a single filter can be directly used to filter the broadband radio frequency signal output by the digital predistortion module 14. The operating bandwidth of the filter can be determined according to the signal frequency to be filtered out, that is, it can be determined by the bandwidth of the broadband signal superimposed on the input narrowband radio frequency signal, so as to ensure that the narrowband radio frequency signal component in the broadband radio frequency signal output by the digital predistortion module 14 passes through, while the broadband signal component is filtered out.

[0072] By applying the above filters, the circuit structure is simple and can achieve better filtering effect, which helps to reduce the production cost of the digital predistortion processing circuit 100.

[0073] Please see Figure 7 In one embodiment, the digital predistortion processing circuit 100 described above further includes a third RF switch 18. The moving contact of the third RF switch 18 is connected to the output port of the digital predistortion module 14. The first stationary contact of the third RF switch 18 is connected to the input port of the filter. The second stationary contact of the third RF switch 18 is used to output a broadband RF signal that has not undergone spread spectrum processing and has been linearized.

[0074] It is understandable that an RF switch can be connected to the output port of the digital predistortion module 14, which is linked with the first RF switch 127 and the second RF switch 125. This allows the broadband RF signal that does not need to be spread spectrum processed and then digitally predistorted linearized to be output directly without passing through a filter. Correspondingly, the broadband RF signal that has been spread spectrum processed and then digitally predistorted linearized is filtered by the filter after passing through the third RF switch 18 before being output.

[0075] To make the above solution easier and more intuitive to understand, a detailed working process of the digital predistortion processing circuit 100 in an application scenario is provided: The digital predistortion processing circuit 100 is powered on and initialized, and the working mode can be manually determined and selected; if the ordinary digital predistortion processing mode is selected, the moving contact and the second stationary contact of the first RF switch 127 are closed, the moving contact and the first stationary contact of the second RF switch 125 are closed, the moving contact and the second stationary contact of the third RF switch 18 are closed, the input RF signal enters the digital predistortion module 14 for digital predistortion linearization processing and is directly output to the outside through the second stationary contact of the third RF switch 18.

[0076] If the narrowband cancellation mode is selected, the moving contact and the first stationary contact of the first RF switch 127 are closed, the moving contact and the second stationary contact of the second RF switch 125 are closed, and the moving contact and the first stationary contact of the third RF switch 18 are closed. The main controller reads the signal power detected by the power detector 128 and controls the broadband signal output by the spread spectrum signal source 124. According to the signal power detected by the power detector 128, the attenuation of the power attenuator 129 is adjusted so that the signal power of the broadband signal is less than the signal power of the input narrowband RF signal. After combining, the corresponding broadband RF signal is obtained and sent to the digital predistortion module 14 for digital predistortion linearization processing. Finally, the linearized broadband RF signal passes through the first stationary contact of the third RF switch 18, enters the filter for filtering, and is then output.

[0077] By applying the third RF switch 18 described above, the filtering of the output RF signal can be better controlled, thereby improving the signal transmission efficiency of the digital predistortion processing circuit 100.

[0078] Please see Figure 8 In one embodiment, the digital predistortion module 14 includes a frequency converter module 141, a digital predistortion module 142, a digital-to-analog converter 143, a first mixer 144, an RF power amplifier 145, a second coupler 146, a second mixer 147, a first local oscillator 148, a first analog-to-digital converter 149, and an adaptive controller 150. The frequency converter module 141, digital predistortion module 142, digital-to-analog converter 143, first mixer 144, RF power amplifier 145, and second coupler 146 are connected in series. The input port of the frequency converter module 141 is connected to the output port of the narrowband spread spectrum module 12. The output port of the second coupler 146 is connected to the input port of the filter module 16. The coupling port of the second coupler 146 is connected to the input port of the second mixer 147. The output port of the second mixer 147 is connected to the first input port of the adaptive controller 150 via the first analog-to-digital converter 149. The second input port of the adaptive controller 150 is connected to the output port of the frequency converter module 141. The feedback output port of the adaptive controller 150 is connected to the feedback input port of the digital predistortion module 142. The output port of the first local oscillator 148 is connected to the local oscillator input ports of the first mixer 144 and the second mixer 147, respectively.

[0079] It is understood that the frequency conversion module 141 can be a circuit module or integrated chip in the art that has the functions of analog signal down-conversion, analog signal to digital signal conversion, and digital down-conversion. Specifically, it can be selected based on the frequency of the input RF signal, the down-conversion frequency, and the digital down-conversion frequency. The digital predistortion module 142, digital-to-analog converter 143, first mixer 144, RF power amplifier 145, and second coupler 146, as well as the second mixer 147, first local oscillator 148, first analog-to-digital converter 149, and adaptive controller 150, can all be conventional devices in the art, such as... Figure 2 The specific models of the corresponding devices shown can be selected according to the characteristics of the transmitted signals in the actual application scenario.

[0080] Specifically, the input broadband RF signal can be a narrowband RF signal input and output after being spread by the narrowband spread spectrum module 12, or it can be a normal input broadband RF signal that does not require spread spectrum processing. This input broadband RF signal first undergoes signal conversion by the frequency conversion module 141, which performs down-conversion, analog-to-digital conversion, and digital down-conversion to transform the input broadband RF signal into a down-converted digital signal that enters the digital predistortion module 142, also known as the digital predistortion chip. The digital predistortion module 142 then performs predistortion processing on the down-converted digital signal. The processed digital signal then sequentially passes through the digital-to-analog converter 143, the first mixer 144, the RF power amplifier 145, and the second coupler 146 before being output.

[0081] Simultaneously, the output RF signal coupled from the second coupler 146 is processed by the second mixer 147 and the first analog-to-digital converter 149, converting the output RF signal into a corresponding digital signal and entering the adaptive controller 150 (i.e., a conventional digital predistortion adaptive controller 150). The adaptive controller 150 adaptively compares the difference between the output digital signal and the digital signal output by the frequency conversion module 141 and adaptively calibrates it before sending it to the digital predistortion module 142. Finally, the digital predistortion module 142 outputs a calibrated digital signal, which already contains the digital predistortion signal of the RF power amplifier 145. This process is repeated through loop feedback for iterative optimization and digital predistortion linearization. Finally, the calibrated digital signal is converted into an analog signal by the digital-to-analog converter 143, then up-converted by the first mixer 144 (i.e., superimposed with the local oscillator signal of the first local oscillator source 148), and then input into the RF power amplifier 145 for amplification and output.

[0082] If the input broadband RF signal is a narrowband RF signal input and a broadband RF signal output after being spread by the narrowband spread spectrum module 12, the broadband RF signal output by the RF power amplifier 145 enters the filter through the first stationary contact of the third RF switch 18 for filtering to remove the spread spectrum signal superimposed during spread spectrum (i.e., the broadband signal of the target bandwidth). The remaining narrowband RF signal is the narrowband RF signal after digital predistortion linearization, which is used for external output. If the input broadband RF signal is a normal input broadband RF signal that does not require spread spectrum processing, the broadband RF signal output by the RF power amplifier 145, i.e., the broadband RF signal after linearization without spread spectrum processing, can be directly output through the second stationary contact of the third RF switch 18. By applying the above-mentioned digital predistortion module 14 for digital predistortion processing of the signal, the application cost is low and the applicability is high.

[0083] Please see Figure 9 In one embodiment, the frequency conversion module 141 includes a third mixer 1411, a second local oscillator 1412, a second analog-to-digital converter 1413, and a digital down-converter 1414. The third mixer 1411, the second analog-to-digital converter 1413, and the digital down-converter 1414 are connected in series. The input port of the third mixer 1411 is connected to the output port of the narrowband spread spectrum module 12. The local oscillator input port of the third mixer 1411 is connected to the output port of the second local oscillator 1412. The output port of the digital down-converter 1414 is connected to the input port of the digital predistortion module 142 and the second input port of the adaptive controller 150, respectively.

[0084] It is understood that in this embodiment, the third mixer 1411 is also... Figure 2 The downconverter shown is either a different model of the same type. Similarly, the second analog-to-digital converter 1413 is also... Figure 2 The analog-to-digital converter shown may be a different model of the same type. The digital down-converter 1414 is also... Figure 2 The digital down-converter 1414 shown may be a different model of the same type. The second local oscillator 1412 is also... Figure 2 The local oscillator shown may be a different model of the same type. The specific model of each of the above devices can be selected according to the processing requirements of the input RF signal, as long as the frequency conversion and conversion function of the input RF signal can be ensured.

[0085] Specifically, the broadband radio frequency signal output by the second RF switch 125 of the narrowband spread spectrum module 12 can be a broadband radio frequency signal that is input from the narrowband RF signal and spread by the narrowband spread spectrum module 12, or it can be a broadband radio frequency signal that is normally input and does not require spread spectrum processing. The specific path is determined by the input RF signal and the signal transmission path selected by the first RF switch 127 and the second RF switch 125. The broadband RF signal output by the second RF switch 125 is then converted by the third mixer 1411, the second analog-to-digital converter 1413, and the digital down-converter 1414 to form a corresponding digital signal, which is then input to the digital predistortion module 142 for further processing. By applying the aforementioned third mixer 1411, second local oscillator 1412, second analog-to-digital converter 1413, and digital down-converter 1414 for the frequency conversion and conversion of the broadband RF signal, application costs can be further reduced and applicability improved.

[0086] In one embodiment, a signal processing device is provided, including the digital predistortion processing circuit 100 described above.

[0087] It is understood that the specific limitations of the digital predistortion processing circuit 100 in this embodiment can be found in the limitations of the corresponding embodiments of the digital predistortion processing circuit 100 above, and will not be repeated here. The signal processing device can be any signal transmission and processing device in the art that uses digital predistortion technology and needs to improve the narrowband cancellation performance of digital predistortion. It is understood in the art that different types of signal processing devices, in addition to including the aforementioned digital predistortion processing circuit 100, may also include other components, such as a main control board, power supply, chassis, antenna, and other functional components, which can be specifically determined according to the inherent structure of the specific signal processing device to which the digital predistortion processing circuit 100 is applied.

[0088] By applying the aforementioned digital predistortion processing circuit 100, when the input RF signal is a narrowband RF signal, it can be spread to a wideband RF signal with a bandwidth within the optimal cancellation bandwidth of the digital predistortion module 14. Furthermore, the digital predistortion module 14 can effectively perform digital predistortion linearization processing on the wideband RF signal. Finally, by filtering the wideband RF signal after digital predistortion linearization, the spread spectrum component in the wideband RF signal is removed, resulting in a linearized narrowband RF signal. This achieves digital predistortion linearization processing of the narrowband RF signal, significantly improving the cancellation capability of the digital predistortion system for narrowband RF signals.

[0089] Please see Figure 10In one embodiment, the signal processing device described above further includes a main controller 201. The narrowband spread spectrum module 12 of the digital predistortion processing circuit 100 includes a spread spectrum signal source 124, a power detector 128, and a power attenuator 129. The main controller 201 is used to output an indication signal to the spread spectrum signal source 124, and to receive the signal power transmitted by the power detector 128 and output a power adjustment signal to the power attenuator 129.

[0090] The main controller 201 is an existing controller on the signal processing equipment. It can automatically control the entire digital predistortion processing process according to a pre-set digital predistortion processing mode. For example, it can select the mode (non-spread spectrum mode under normal broadband RF signal input, or spread spectrum mode under narrowband RF signal input) and complete the corresponding RF switch selection and switching, triggering the broadband signal generation of the spread spectrum signal source 124, indicating the attenuation power of the power attenuator 129, and regulating the predistortion process of the digital predistortion module 142. The main controller 201 can be an MCU, a CPU, or a programmable logic device commonly used in this field.

[0091] It is understood that in the above embodiments, the selection and switching of each RF switch, the triggering of the broadband signal generation of the spread spectrum signal source 124, and the setting of the attenuation power of the power attenuator 129 can all be manually set in advance, or can be automatically completed by an external independent controller (simply set it in advance to the independent controller by means of instructions according to the manual setting method). However, in this embodiment, the control terminals of each RF switch, the control terminal of the spread spectrum signal source 124, the output terminal of the power detector 128, and the control terminal of the power attenuator 129 can be directly connected to the main controller 201 built into the signal processing equipment, so that the main controller 201 can automatically complete the control of the entire digital predistortion processing process according to the preset settings.

[0092] The main controller 201 can automatically control the output of the spread spectrum signal source 124, enabling it to quickly output a broadband signal of the target bandwidth to the combiner 122 when a broadband signal of the target bandwidth is required, thus completing the combined spread spectrum processing of the input narrowband RF signal. Simultaneously, the main controller 201 can automatically control the power attenuator 129 to reduce the power of the broadband signal of the target bandwidth based on the signal power transmitted by the power detector 128. This ensures that the signal power of the broadband signal of the target bandwidth is less than that of the input narrowband RF signal, thereby limiting the signal power of the corresponding output broadband RF signal after combined spread spectrum processing, reducing the operating current in the subsequent digital predistortion processing link, and effectively saving energy for the entire device. Therefore, the application of the main controller 201 can significantly improve the performance of digital predistortion processing.

[0093] In one embodiment, such as Figure 10 As shown, the digital predistortion processing circuit 100 also includes a third RF switch 18. The narrowband spread spectrum module 12 also includes a first RF switch 127 and a second RF switch 125. The main controller 201 is electrically connected to the switch control terminals of the first RF switch 127 and the second RF switch 125, as well as the switch control terminal of the third RF switch 18. The main controller 201 is also used to output switch control signals to the first RF switch 127, the second RF switch 125, and the third RF switch 18, respectively.

[0094] It is understood that the explanation of the third RF switch 18, the first RF switch 127 and the second RF switch 125 in this embodiment can be referred to the explanation of the third RF switch 18, the first RF switch 127 and the second RF switch 125 in the corresponding embodiment of the digital predistortion processing circuit 100 described above, and will not be repeated in this embodiment.

[0095] Specifically, the main controller 201 has multiple control pins. The switch control terminals of the third RF switch 18, the first RF switch 127, and the second RF switch 125 can be directly or indirectly electrically connected to the control pins on the main controller 201 to receive the switch control signals output by the main controller 201. After receiving the switch control signals, the third RF switch 18, the first RF switch 127, and the second RF switch 125 switch the closed state between their moving and stationary contacts, thereby forming corresponding signal paths. Through the circuit connection between the above-mentioned RF switches and the main controller 201, the selection and switching control of each RF switch can be automatically completed, thereby effectively improving the efficiency of digital predistortion processing mode switching for input signals of different bandwidths in the signal processing equipment.

[0096] In one embodiment, the signal processing device is any one of a base amplifier, a repeater, a radio frequency remote amplifier, a track power amplifier, an integrated power amplifier, and a receiver.

[0097] It is understood that the signal processing device applying the above-described digital predistortion processing circuit 100 can be any of the following in the art: base amplifier (i.e., power amplifier in a base station of a communication system), repeater, radio frequency remote unit, track power amplifier, integrated power amplifier (i.e., an integrated power amplifier device in which radio frequency power amplifier and other power amplifier-related components are integrated into the same structural base), and receiver, to improve the device's digital predistortion narrowband cancellation performance. Those skilled in the art will understand that the foregoing examples are only a few signal processing devices, and the above-described digital predistortion processing circuit 100 can also be applied to other devices that require improved digital predistortion narrowband cancellation performance.

[0098] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0099] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A digital predistortion processing circuit, characterized in that, include: Narrowband spread spectrum module, used to spread the input narrowband radio frequency signal into a wideband radio frequency signal; The bandwidth of the broadband radio frequency signal is a preset bandwidth; A digital predistortion module is used to perform digital predistortion linearization processing on the broadband radio frequency signal to obtain a linearized broadband radio frequency signal; the preset bandwidth is located within the optimal cancellation bandwidth of the digital predistortion module. A filtering module is used to filter the linearized broadband radio frequency signal to obtain a linearized narrowband radio frequency signal. The narrowband spread spectrum module includes a combiner and a spread spectrum signal source. The first input port of the combiner is used to receive the narrowband radio frequency signal, and the second input port of the combiner is connected to the output of the spread spectrum signal source. The spread spectrum signal source is used to output a broadband signal with a target bandwidth to the combiner after receiving an indication signal output by the main controller of the predistortion system. The combiner is used to combine the broadband signal with the narrowband radio frequency signal and output the resulting broadband radio frequency signal to the digital predistortion module. The filtering module is a filter whose filtering bandwidth corresponds to the spreading bandwidth of the narrowband spreading module.

2. The digital predistortion processing circuit according to claim 1, characterized in that, The narrowband spread spectrum module also includes a first coupler, a power detector, and a power attenuator; The input port of the first coupler is used to receive the narrowband radio frequency signal, the output port of the first coupler is connected to the first input port of the combiner, the coupling port of the first coupler is connected to the input port of the power detector, the input terminal of the power attenuator is connected to the output terminal of the spread spectrum signal source, and the output terminal of the power attenuator is connected to the second input port of the combiner. The power detector is used to detect the signal power of the narrowband radio frequency signal and transmit it to the main controller. The power attenuator is used to attenuate the signal power of the broadband signal to less than the signal power of the narrowband radio frequency signal after receiving the power adjustment signal output by the main controller.

3. The digital predistortion processing circuit according to claim 2, characterized in that, The narrowband spread spectrum module also includes a first radio frequency switch and a second radio frequency switch; The moving contact of the first RF switch is used to access the narrowband RF signal, the first stationary contact of the first RF switch is connected to the input port of the first coupler, and the second stationary contact of the first RF switch is connected to the first stationary contact of the second RF switch. The second stationary contact of the second RF switch is connected to the combining port of the combiner, and the moving contact of the second RF switch is connected to the input port of the digital predistortion module.

4. The digital predistortion processing circuit according to any one of claims 1 to 3, characterized in that, The filtering module is a filter, the input port of the filter is connected to the output port of the digital predistortion module, and the output port of the filter is used to output the linearized narrowband radio frequency signal.

5. The digital predistortion processing circuit according to claim 4, characterized in that, It also includes a third RF switch, the moving contact of which is connected to the output port of the digital predistortion module, the first stationary contact of which is connected to the input port of the filter, and the second stationary contact of which is used to output a broadband RF signal that has not been spread and has been linearized.

6. The digital predistortion processing circuit according to claim 1, characterized in that, The digital predistortion module includes a frequency conversion module, a digital predistortion module, a digital-to-analog converter, a first mixer, an RF power amplifier, a second coupler, a second mixer, a first local oscillator, a first analog-to-digital converter, and an adaptive controller; The frequency conversion module, the digital predistortion module, the digital-to-analog converter, the first mixer, the RF power amplifier, and the second coupler are connected in series, and the input port of the frequency conversion module is connected to the output port of the narrowband spread spectrum module. The output port of the second coupler is connected to the input port of the filter module, the coupling port of the second coupler is connected to the input port of the second mixer, the output port of the second mixer is connected to the first input port of the adaptive controller through the first analog-to-digital converter, the second input port of the adaptive controller is connected to the output port of the frequency conversion module, and the feedback output port of the adaptive controller is connected to the feedback input port of the digital predistortion module. The output port of the first local oscillator is connected to the local oscillator input ports of the first mixer and the second mixer, respectively.

7. The digital predistortion processing circuit according to claim 6, characterized in that, The frequency conversion module includes a third mixer, a second local oscillator, a second analog-to-digital converter, and a digital down-converter; The third mixer, the second analog-to-digital converter, and the digital down-converter are connected in series. The input port of the third mixer is connected to the output port of the narrowband spread spectrum module, the local oscillator input port of the third mixer is connected to the output port of the second local oscillator source, and the output port of the digital down-converter is connected to the input port of the digital predistortion module and the second input port of the adaptive controller, respectively.

8. A signal processing device, characterized in that, Includes the digital predistortion processing circuit as described in claim 1.

9. The signal processing apparatus according to claim 8, characterized in that, It also includes a main controller, and the narrowband spread spectrum module of the digital predistortion processing circuit includes a spread spectrum signal source, a power detector, and a power attenuator; The main controller is used to output an indication signal to the spread spectrum signal source, and to receive the signal power transmitted by the power detector and output a power adjustment signal to the power attenuator.

10. The signal processing apparatus according to claim 9, characterized in that, The digital predistortion processing circuit also includes a third radio frequency switch, and the narrowband spread spectrum module also includes a first radio frequency switch and a second radio frequency switch. The main controller is electrically connected to the switch control terminals of the first RF switch and the second RF switch, as well as the switch control terminal of the third RF switch. The main controller is also used to output switch control signals to the first RF switch, the second RF switch, and the third RF switch, respectively.

11. The signal processing apparatus according to any one of claims 8 to 10, characterized in that, The signal processing equipment is any one of the following: base amplifier equipment, repeater equipment, radio frequency remote equipment, track power amplifier equipment, integrated power amplifier, and receiver.

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