CN111226397B - Method and device for digital predistortion processing in beamforming - Google Patents
Method and device for digital predistortion processing in beamforming Download PDFInfo
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- CN111226397B CN111226397B CN201780095963.6A CN201780095963A CN111226397B CN 111226397 B CN111226397 B CN 111226397B CN 201780095963 A CN201780095963 A CN 201780095963A CN 111226397 B CN111226397 B CN 111226397B
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Abstract
The invention aims to provide a method and a device for digital predistortion processing in beam forming; compared with the prior art, the invention selects a reference PA channel from the wireless radio frequency channels corresponding to the beam forming, corrects the beam forming weight stored in advance according to the amplitude phase difference of other PA channels relative to the reference PA channel, and meets the forming condition of an ideal beam.
Description
Technical Field
The present invention relates to the field of communications technologies, and in particular, to a technique for performing digital predistortion processing in beamforming.
Background
In 5G large-scale mimo (Multiple Input Multiple Output) applications, it is impossible to apply dedicated DPD (Digital Pre-Distortion) to each PA (Power Amplifier) due to the presence of many antennas. For example, in RF (radio frequency) beamforming, one RF channel may have many active antennas and their corresponding PAs. It is difficult to have all PAs have the same performance for many physical reasons. Therefore, a single DPD of one selected PA cannot be used for other PAs, otherwise the ACPR (Adjacent Channel Power Ratio) of the antenna array would be poor and the radiation pattern of the beam would not be the desired one. To make the PA easier, cheaper and more accurate in the required beam pattern, the compensator should be designed such that the single DPD can be applied to all PAs.
In the prior art, to solve the above problem, phase derotation is usually performed in all feedback paths at first, and then DPD is estimated for all PAs in a cascaded manner. However, this approach is too complex for large antenna arrays and is not feasible. Multiple feedback paths will introduce synchronization problems.
Disclosure of Invention
The invention aims to provide a method and a device for digital predistortion processing in beam forming.
According to an aspect of the present invention, there is provided a method for digital predistortion processing in beamforming, wherein the method comprises:
a, selecting a reference PA channel from wireless radio frequency channels corresponding to beam forming, and performing digital predistortion processing on the reference PA channel;
b, according to the output signal of the reference PA channel and the output signals of the rest PA channels in the wireless radio frequency channel at the same time, correcting the pre-stored beam forming weight of the rest PA channels;
and c, carrying out beam forming on the wireless radio frequency channel according to the beam forming weight of the reference PA channel and the beam forming weight after the modification of the rest PA channels.
Preferably, the step b includes:
delaying the reference PA channel to synchronize with each of the rest PA channels in the wireless radio frequency channel;
wherein the step c comprises:
and carrying out beam forming on the wireless radio frequency channel according to the delayed beam forming weight of the reference PA channel and the corrected beam forming weight of the rest PA channels.
Preferably, the method comprises:
and equally dividing the input signal to obtain a plurality of wireless radio frequency channels, wherein the power value of each wireless radio frequency channel is the same.
Preferably, the step b includes:
and correcting the pre-stored beamforming weights of the rest of the PA channels by utilizing an analog multiplier and/or an analog divider according to the output signal of the reference PA channel and the output of the rest of the PA channels at the same moment in the wireless radio frequency channel.
Preferably, the step b includes:
obtaining pre-stored beam forming weights of the rest PA channels in the wireless radio frequency channels from an original codebook;
and correcting the pre-stored beam forming weight of each other PA channel according to the output signal of the reference PA channel and each output signal of each other PA channel in the wireless radio frequency channel at the same moment.
Preferably, the antenna arrays corresponding to the beamforming are linearly uniform.
According to another aspect of the present invention, there is also provided a processing apparatus for performing digital predistortion processing in beamforming, wherein the processing apparatus includes:
the selection device is used for selecting a reference PA channel from wireless radio frequency channels corresponding to beam forming and carrying out digital pre-distortion processing on the reference PA channel;
a correcting device, configured to correct the pre-stored beamforming weights of the remaining PA channels according to the output signal of the reference PA channel and each output signal of the remaining PA channels at the same time in the radio frequency channel;
and the executing device is used for executing beam forming on the wireless radio frequency channel according to the beam forming weight of the reference PA channel and the beam forming weight after the modification of the rest PA channels.
Preferably, the correction device is configured to:
delaying the reference PA channel to synchronize with each of the rest PA channels in the wireless radio frequency channel;
wherein the execution device is configured to:
and carrying out beam forming on the wireless radio frequency channel according to the delayed beam forming weight of the reference PA channel and the corrected beam forming weight of the rest PA channels.
Preferably, the processing means comprises:
and the equalizing device is used for equalizing the input signals to obtain a plurality of radio frequency channels, wherein the power value of each radio frequency channel is the same.
Preferably, the correction device is configured to:
and correcting the pre-stored beamforming weights of the rest of the PA channels by utilizing an analog multiplier and/or an analog divider according to the output signal of the reference PA channel and the output of the rest of the PA channels at the same moment in the wireless radio frequency channel.
Preferably, the correction device is configured to:
obtaining pre-stored beam forming weights of the rest PA channels in the wireless radio frequency channels from an original codebook;
and correcting the pre-stored beam forming weight of each other PA channel according to the output signal of the reference PA channel and each output signal of each other PA channel in the wireless radio frequency channel at the same moment.
Preferably, the antenna arrays corresponding to the beamforming are linearly uniform.
Compared with the prior art, the invention selects a reference PA channel from the wireless radio frequency channels corresponding to the beam forming, performing digital pre-distortion processing on the reference PA channel, and according to an output signal of the reference PA channel, and each output signal of each other PA channel in the wireless radio frequency channel at the same time corrects the beam forming weight pre-stored by each other PA channel, and further, according to the beamforming weight of the reference PA channel and the beamforming weights corrected by the rest of the PA channels, the beam forming is carried out on the wireless radio frequency channels, so that the output signals of the wireless radio frequency channels are corrected to be consistent, the frequency spectrum and the radiation pattern of the beam forming are greatly improved, and by adopting the mode, so that the pointing direction of the antenna array corresponding to the beamforming is not changed, but the corresponding side lobe value is adjusted. According to the amplitude phase differences of other PA channels relative to the reference PA channel, the beam weights stored in advance are corrected to meet the forming condition of an ideal beam, and because the amplitude phase differences are caused by the characteristic differences of the PAs, the corrected beam forming weights eliminate the differences, so that the DPD designed for the reference PA can be used for all the PAs, the ACPR of each PA meets the requirement, and the beam shape is close to the ideal beam.
Drawings
Other features, objects and advantages of the invention will become more apparent upon reading of the detailed description of non-limiting embodiments made with reference to the following drawings:
fig. 1 illustrates a flow diagram of a method of digital predistortion processing in beamforming in accordance with an aspect of the present invention;
fig. 2 is a diagram illustrating digital predistortion processing in beamforming in accordance with a preferred embodiment of the present invention;
fig. 3 to 6 show schematic diagrams of digital predistortion processing according to the prior art;
fig. 7 to 8 are diagrams illustrating a digital predistortion process in beamforming according to another preferred embodiment of the present invention;
FIG. 9 shows a schematic diagram of a digital pre-distortion process according to the prior art;
fig. 10 to 11 are diagrams illustrating a digital predistortion process in beamforming according to another preferred embodiment of the present invention;
fig. 12 shows the radiation patterns of compensated and uncompensated beams.
The same or similar reference numbers in the drawings identify the same or similar elements.
Detailed Description
The term "base station" as used herein may be considered synonymous with, and sometimes referred to hereinafter as: a node B, an evolved node B, an eNodeB, an eNB, a Base Transceiver Station (BTS), an RNC, etc., and may describe a transceiver that communicates with a mobile terminal and provides radio resources for it in a wireless communication network that may span multiple technology generations. The base stations discussed herein may have all of the functionality associated with conventional well-known base stations, except for the ability to implement the methods discussed herein.
The methods discussed below may be implemented by hardware, software, firmware, middleware, microcode, hardware description languages, or any combination thereof. When implemented in software, firmware, middleware or microcode, the program code or code segments to perform the necessary tasks may be stored in a machine or computer readable medium such as a storage medium. The processor(s) may perform the necessary tasks.
Specific structural and functional details disclosed herein are merely representative and are provided for purposes of describing example embodiments of the present invention. The present invention may, however, be embodied in many alternate forms and should not be construed as limited to only the embodiments set forth herein. It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element may be termed a second element, and, similarly, a second element may be termed a first element, without departing from the scope of example embodiments. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
It will be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element or intervening elements may be present. In contrast, when an element is referred to as being "directly connected" or "directly coupled" to another element, there are no intervening elements present. Other words used to describe the relationship between elements (e.g., "between" versus "directly between", "adjacent" versus "directly adjacent to", etc.) should be interpreted in a similar manner.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used herein, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
It should also be noted that, in some alternative implementations, the functions/acts noted may occur out of the order noted in the figures. For example, two figures shown in succession may, in fact, be executed substantially concurrently, or the figures may sometimes be executed in the reverse order, depending upon the functionality/acts involved.
Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which example embodiments belong. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
The present invention is described in further detail below with reference to the attached drawing figures.
Fig. 1 illustrates a flow diagram of a method of digital predistortion processing in beamforming in accordance with an aspect of the present invention.
In step S101, the processing apparatus 1 selects a reference PA channel from the radio frequency channels corresponding to beamforming, and performs digital predistortion processing on the reference PA channel.
Specifically, the beamforming has a corresponding radio frequency channel, and in step S101, the processing apparatus 1 may select one radio frequency channel as a reference PA channel, and perform Digital Predistortion (DPD) processing on the reference PA channel, where the digital predistortion processing may be, for example, conventional digital predistortion processing.
Preferably, the antenna arrays corresponding to the beamforming are linearly uniform.
Here, it is assumed that the antenna arrays corresponding to the beamforming are linearly uniform.
In step S102, the processing apparatus 1 corrects the beamforming weights pre-stored in the remaining PA channels according to the output signal of the reference PA channel and the output signals of the remaining PA channels at the same time in the radio frequency channel.
Specifically, each rf channel may have a corresponding beamforming weight in advance, for example, assuming that there are two rf channels, one of which is selected as the reference PA channel and has a beamforming weight of w0The output communication signal stream is x0The beam forming weight of the other wireless radio frequency channel is w1Since different PAs have different capabilities, it is assumed that the output communication signal stream of the other radio channel becomes x1Then, in step S102, the processing means 1 depend on the output signal x of the reference PA channel0And the output signals x1 of the rest PA channels in the wireless radio frequency channels at the same time, and correcting the beam forming weight w pre-stored in the rest PA channels1Then, the modified beamforming weights of the remaining PA channels are as follows:
it should be understood by those skilled in the art that the foregoing parameters are merely exemplary and are not intended to limit the present invention in any way, and that other information, now or hereafter, regarding the parameters, as may be applicable to the present invention, is also intended to be included within the scope of the present invention and is hereby incorporated by reference.
Preferably, in step S102, the processing device 1 corrects the pre-stored beamforming weights of the rest of PA channels by using an analog multiplier and/or an analog divider according to the output signal of the reference PA channel and the outputs of the rest of PA channels at the same time in the radio frequency channels.
Specifically, in step S102, the processing device 1 may implement the above function by using an analog multiplier and/or an analog divider, for example, the modification of another wireless rf channel calculated by the processing device 1 described in the previous examplePositive and negative beamforming weights
The processing means 1 may first output a communication signal stream x based on the radio frequency channel selected as the reference PA channel0And an output communication signal stream x of another radio frequency channel1Obtaining by means of an analog divider
Then according to the pre-stored beam forming weight w of the other wireless radio frequency channel1Obtaining the modified beamforming weight by using an analog multiplier
Preferably, in step S102, the processing device 1 obtains the pre-stored beamforming weights of the rest PA channels in the wireless radio frequency channel from the original codebook; and correcting the pre-stored beam forming weight of each other PA channel according to the output signal of the reference PA channel and each output signal of each other PA channel in the wireless radio frequency channel at the same moment.
Specifically, the beamforming weights of the wireless radio frequency channels may be pre-stored in an original codebook (codebook), and in step S102, the processing apparatus 1 obtains pre-stored beamforming weights of the wireless radio frequency channels from the original codebook, where the pre-stored beamforming weights include both the pre-stored beamforming weight of the reference PA channel and the pre-stored beamforming weights of the remaining PA channels; here, the beamforming weights are weights of ideal beams stored in the original codebook in advance. And then, calculating new beamforming weights of the rest of PA channels according to the output signals of the reference PA channel and the output signals of the rest of PA channels at the same time in the wireless radio frequency channel, thereby correcting the prestored beamforming weights. Here, the processing apparatus 1 obtains the weight of the ideal beam from the original codebook, and the analog signal difference of each remaining PA channel in the radio frequency channel with respect to the reference PA channel, and then corrects to obtain a new beamforming weight according to the ideal beam weight.
For example, assume beamforming has 4 radio channels, where one of the radio channels selected as the reference PA channel has a pre-stored beamforming weight of w0Corresponding to an output communication signal stream of x0The pre-stored beam forming weights of the rest PA channels in the 4 wireless radio frequency channels are w respectively1，w2，w3The corresponding output signal streams are x respectively1，x2，x3The beamforming codebook is as follows:
If all PAs are the same, the ideal beam would be the following equation:
y＝x0w0+x0w1+x0w2+x0w3w0＝1
however, because of the inconsistency of the PA performance, in step S102, the processing apparatus 1 recalculates new beamforming weights for the remaining PA channels, so as to correct the pre-stored beamforming weights, and apply the following equation:
wherein the content of the first and second substances,
i.e. the modified beamforming weights for the remaining PA channels.
In step S103, the processing device 1 performs beamforming on the radio frequency channel according to the beamforming weight of the reference PA channel and the beamforming weights corrected by the remaining PA channels.
Specifically, after the processing device 1 modifies the pre-stored beamforming weights of the remaining PA channels in step S102 to obtain modified beamforming weights of the remaining PA channels, in step S103, the processing device 1 performs beamforming on the wireless rf channels according to the modified beamforming weights and the unchanged pre-stored beamforming weights of the reference PA channels, so that the output signals of the wireless rf channels are modified to be consistent, and the beamformed spectrum and radiation pattern are greatly improved.
In this way, the pointing direction of the antenna array corresponding to the beamforming is not changed, but the corresponding side lobe value is adjusted.
Preferably, in step S102, the processing device 1 performs a delay process on the reference PA channel to synchronize the reference PA channel with each of the rest PA channels in the radio frequency channel; in step S103, the processing device 1 performs beamforming on the radio frequency channel according to the delayed beamforming weight of the reference PA channel and the modified beamforming weights of the other PA channels.
Specifically, since the rest of the PA channels in the radio frequency channel need to be processed by using an analog multiplier and/or an analog divider, and the reference PA channel does not need to be processed, in step S102, the processing apparatus 1 further needs to perform a delay process on the reference PA channel so as to synchronize with each of the rest of the PA channels in the radio frequency channel.
For example, as shown in fig. 2, one compensated beamforming weight vector is designed to be applied to each PA. Wherein the communication signal stream x0Transmitted and then converted to an Analog waveform by a DAC (Digital-to-Analog Converter). The signal is split into n branches, where n is assumed to be 4. One of the radio frequency channels, channel 1 as shown in fig. 2, is selected as the reference PA channel to perform as usualRow DPD. Thus, the DPD will be a unified DPD executed by all PAs. It can also be seen in fig. 2 that a delay unit is applied in the reference PA channel, which can be compensated for in production. The bandwidth of the analogic computation circuit should be wide enough.
The beamforming codebook is
Wave beam spot is
Here, it is assumed that the antenna array is linearly uniform.
If all PAs are identical, the ideal beam would be y-x0w0+x0w1+x0w2+x0w3w01. But due to the disparity in PA performance, the following equation can be applied to extract x by a division circuit0To obtain phase and amplitude differences.
By the above derivation, the weight of beamforming is a time-varying Vector Modulator (VM), which accumulates the PA difference. The modified beamforming weights of the radio frequency channels make the antenna array consistent again with respect to the reference PA channel, and thus the beamformed spectrum and radiation pattern are greatly improved. The original beamforming codebook is applied to the vector modulator.
It should be understood by those skilled in the art that the above parameters are only examples and should not be construed as limiting the present invention in any way, and other information about the parameters now known or later developed, such as those applicable to the present invention, should also be included within the scope of the present invention and is hereby incorporated by reference.
Preferably, the method further comprises step S104 (not shown). In step S104, the processing apparatus 1 equally divides the input signal to obtain a plurality of radio frequency channels, where the power value of each radio frequency channel is the same.
Specifically, in step S104, the processing apparatus 1 may equally divide the beamformed input signal, for example, in the previous example, the input signal is divided into n branches, each branch has the same power, and here, assuming that n is 4, 4 radio frequency channels may be obtained, where the power value of each radio frequency channel is the same.
Fig. 3 to 11 show the prior art and the advantageous effects after applying the present invention, respectively.
Fig. 3 shows the spectrum of a prior art antenna array with 4 PAs, which are slightly different.
Fig. 4 shows the spectrum of one of the PAs 1 of fig. 3, the PA1 being used as a reference PA in the simulation.
Fig. 5 shows the frequency spectrum of the reference PA of fig. 4 after DPD is performed.
Fig. 6 shows the spectrum of a beam in which a single DPD of the reference PA is applied directly to all the PAs, but without any compensation.
Fig. 7 shows a frequency spectrum employing the present invention. As can be seen from fig. 6 to 7, ACPR is reduced by approximately 30dB, which means that it is not feasible to apply a single DPD of the reference PA directly to all PAs as shown in fig. 3.
Fig. 8 shows the AM-AM (amplitude) curve of the compensated beam of the present invention. It is linear and has no saturated bending phenomenon.
Fig. 9 shows that a single DPD of a reference PA is applied directly to all the PAs, but without compensation, which is seen to be completely ineffective.
Fig. 10 and 11 show the difference in phase and amplitude between the reference PA channel and the other PA channels. The difference can be seen as a linear distribution, which can be represented by a set of averages or linearity. Unfortunately these linear models cannot be used for the entire analog signal and cannot be compensated in the digital domain. It can be seen that the problem cannot be solved with a simple linear fit.
Fig. 12 shows the radiation patterns of compensated and uncompensated beams. The beam shape due to the difference in PA characteristics is not compensated, although the direction is unchanged, the main lobe amplitude becomes smaller and the side lobe becomes larger, and these deteriorations vary with the difference in PA, the larger the difference, the worse the deteriorations. And the compensated beam will approach the ideal beam.
The invention has the advantages of simplicity and effectiveness, and will relax the production requirements of PA. The invention enhances the robustness of the RF system in which some compensation mechanisms have to be used, otherwise the risk will be high due to unsatisfactory non-uniformity of the PA. If this happens, the only way is to compensate (backoff) the working point (work point), but it will deviate from the DPD's idea.
According to another aspect of the present invention, there is also provided a processing apparatus for performing digital predistortion processing in beamforming, wherein the processing apparatus 1 comprises a selecting apparatus, a modifying apparatus and an executing apparatus.
The selection device selects a reference PA channel from the wireless radio frequency channels corresponding to the beam forming, and performs digital predistortion processing on the reference PA channel.
In particular, the beamforming has corresponding radio frequency channels, and the selecting means may select one of the radio frequency channels as a reference PA channel and perform Digital Predistortion (DPD) processing on the reference PA channel, which may be, for example, conventional digital predistortion processing.
Preferably, the antenna arrays corresponding to the beamforming are linearly uniform.
Here, it is assumed that the antenna arrays corresponding to the beamforming are linearly uniform.
And the correcting device corrects the pre-stored beam forming weight of each other PA channel according to the output signal of the reference PA channel and each output signal of each other PA channel in the wireless radio frequency channel at the same moment.
Specifically, each rf channel may have a corresponding beamforming weight in advance, for example, assuming that there are two rf channels, one of which is selected as the beamforming weight of the rf channel of the reference PA channelIs w0The output communication signal stream is x0The beam forming weight of the other wireless radio frequency channel is w1Since different PAs have different capabilities, it is assumed that the output communication signal stream of the other radio channel becomes x1The correction device then corrects the output signal x according to the reference PA channel0And the output signals x1 of the rest PA channels in the wireless radio frequency channels at the same time modify the beam forming weight w pre-stored in the rest channels1Then, the beamforming weights after the other PA channels are modified are as follows:
it should be understood by those skilled in the art that the foregoing parameters are merely exemplary and are not intended to limit the present invention in any way, and that other information, now or hereafter, regarding the parameters, as may be applicable to the present invention, is also intended to be included within the scope of the present invention and is hereby incorporated by reference.
Preferably, the correcting device corrects the pre-stored beamforming weights of the rest of PA channels by using an analog multiplier and/or an analog divider according to the output signal of the reference PA channel and the outputs of the rest of PA channels at the same time in the radio frequency channel.
In particular, the correction means may implement the above function by means of an analog multiplier and/or an analog divider, for example calculated by the processing means 1 described in the previous example
The modified beamforming weight of the other radio frequency channel
The correction means may first output a communication signal stream x based on the radio frequency channel selected as the reference PA channel0And an output communication signal stream x of another radio frequency channel1Obtaining by means of an analog divider
Then according to the pre-stored beam forming weight w of the other wireless radio frequency channel1Obtaining the modified beamforming weight by using an analog multiplier
Preferably, the correcting device obtains the pre-stored beam forming weights of the rest PA channels in the wireless radio frequency channel from the original codebook; and correcting the pre-stored beam forming weight of each other PA channel according to the output signal of the reference PA channel and each output signal of each other PA channel in the wireless radio frequency channel at the same moment.
Specifically, the beamforming weight of each rf channel may be pre-stored in an original codebook (codebook), and the modifying device obtains the pre-stored beamforming weight of each rf channel from the original codebook, where the pre-stored beamforming weight includes both the pre-stored beamforming weight of the reference PA channel and the pre-stored beamforming weights of the other PA channels; here, the beamforming weights are weights of ideal beams stored in the original codebook in advance. And then, calculating new beamforming weights of the rest of PA channels according to the output signals of the reference PA channel and the output signals of the rest of PA channels at the same time in the wireless radio frequency channel, thereby correcting the prestored beamforming weights. The correcting device obtains the weight of the ideal wave beam from the original codebook, and the analog signal difference of each rest PA channel in the wireless radio frequency channel relative to the reference PA channel, and then corrects the ideal wave beam weight to obtain a new wave beam forming weight.
For example, assume beamforming has 4 radio channels, where one of the radio channels selected as the reference PA channel has a pre-stored beamforming weight of w0With corresponding output communication signal stream of x0The rest of the 4 wireless radio frequency channels are all PA channelsThe pre-stored beamforming weights for a track are each w1，w2，w3The corresponding output signal streams are x respectively1，x2，x3The beamforming codebook is as follows:
If all PAs are the same, the ideal beam would be the following equation:
y＝x0w0+x0w1+x0w2+x0w3w0＝1
however, because of the inconsistency of the PA performances, the correction apparatus recalculates the new beamforming weights of the remaining PA channels, so as to correct the pre-stored beamforming weights, applying the following equation:
wherein the content of the first and second substances,
i.e. the modified beamforming weights for the remaining PA channels.
And the executing device executes the beam forming to the wireless radio frequency channel according to the beam forming weight of the reference PA channel and the beam forming weight after the modification of the rest PA channels.
Specifically, after the correction device corrects the pre-stored beamforming weights of the other PA channels to obtain the corrected beamforming weights of the other PA channels, the execution device performs beamforming on the radio frequency channels according to the corrected beamforming weights and the unchanged pre-stored beamforming weights of the reference PA channel, so that output signals of the radio frequency channels are corrected to be consistent, and the beamformed frequency spectrum and the radiation pattern are greatly improved.
In this way, the pointing direction of the antenna array corresponding to the beamforming is not changed, but the corresponding side lobe value is adjusted.
Preferably, the correction device performs delay processing on the reference PA channel to synchronize the reference PA channel with each of the rest PA channels in the radio frequency channel; and the execution device carries out beam forming on the wireless radio frequency channel according to the delayed beam forming weight of the reference PA channel and the corrected beam forming weight of each of the rest PA channels.
Specifically, since the rest of the PA channels in the radio frequency channel need to be processed by using an analog multiplier and/or an analog divider, and the reference PA channel does not need to be processed, the correction apparatus needs to delay the reference PA channel to synchronize the reference PA channel with each of the rest of the PA channels in the radio frequency channel.
For example, as shown in fig. 2, one compensated beamforming weight vector is designed to be applied to each PA. Wherein the communication signal stream x0Transmitted and then converted to an Analog waveform by a DAC (Digital-to-Analog Converter). The signal is split into n branches, where n is assumed to be 4. One of the radio frequency channels, channel 1 as shown in fig. 2, is selected as the reference PA channel to perform DPD as usual. Thus, the DPD will be a unified DPD executed by all PAs. It can also be seen in fig. 2 that a delay unit is applied in the reference PA channel, which can be compensated for in production. The bandwidth of the analogic computation circuit should be wide enough.
The beamforming codebook is
Wave beam spot is
Here, it is assumed that the antenna array is linearly uniform.
If all PAs are identical, the ideal beam would be y-x0w0+x0w1+x0w2+x0w3w01. But due to the disparity in PA performance, the following equation can be applied to extract x by a division circuit0To obtain phase and amplitude differences.
By the above derivation, the weight of beamforming is a time-varying Vector Modulator (VM), which accumulates the PA difference. The modified beamforming weights of the radio frequency channels make the antenna array consistent again with respect to the reference PA channel, and thus the beamformed spectrum and radiation pattern are greatly improved. The original beamforming codebook is applied to the vector modulator.
It should be understood by those skilled in the art that the foregoing parameters are merely exemplary and are not intended to limit the present invention in any way, and that other information, now or hereafter, regarding the parameters, as may be applicable to the present invention, is also intended to be included within the scope of the present invention and is hereby incorporated by reference.
Preferably, the treatment device 1 further comprises averaging means (not shown). The averaging device averages input signals to obtain a plurality of radio frequency channels, wherein the power value of each radio frequency channel is the same.
Specifically, the averaging device may average the beamformed input signal, for example, in the previous example, the input signal is divided into n branches, each branch has the same power, and here, assuming that n is 4, 4 radio frequency channels may be obtained, where the power value of each radio frequency channel is the same.
It should be noted that the present invention may be implemented in software and/or in a combination of software and hardware, for example, as an Application Specific Integrated Circuit (ASIC), a general purpose computer or any other similar hardware device. In one embodiment, the software program of the present invention may be executed by a processor to implement the steps or functions described above. Also, the software programs (including associated data structures) of the present invention can be stored in a computer readable recording medium, such as RAM memory, magnetic or optical drive or diskette and the like. Further, some of the steps or functions of the present invention may be implemented in hardware, for example, as circuitry that cooperates with the processor to perform various steps or functions.
In addition, some of the present invention can be applied as a computer program product, such as computer program instructions, which when executed by a computer, can invoke or provide the method and/or technical solution according to the present invention through the operation of the computer. Program instructions which invoke the methods of the present invention may be stored on a fixed or removable recording medium and/or transmitted via a data stream on a broadcast or other signal-bearing medium and/or stored within a working memory of a computer device operating in accordance with the program instructions. An embodiment according to the invention herein comprises an apparatus comprising a memory for storing computer program instructions and a processor for executing the program instructions, wherein the computer program instructions, when executed by the processor, trigger the apparatus to perform a method and/or solution according to embodiments of the invention as described above.
It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned. Furthermore, it is obvious that the word "comprising" does not exclude other elements or steps, and the singular does not exclude the plural. A plurality of units or means recited in the apparatus claims may also be implemented by one unit or means in software or hardware. The terms first, second, etc. are used to denote names, but not any particular order.
Claims (8)
1. A method for digital predistortion processing in beamforming, wherein the method comprises:
a, selecting a reference PA channel from wireless radio frequency channels corresponding to beam forming, and carrying out digital pre-distortion processing on the reference PA channel;
b, according to the output signal of the reference PA channel and the output signals of the rest PA channels in the wireless radio frequency channel at the same time, correcting the pre-stored beam forming weight of the rest PA channels;
c, according to the beam forming weight of the reference PA channel and the beam forming weight corrected by the rest PA channels, carrying out beam forming on the wireless radio frequency channel;
wherein, the antenna arrays corresponding to the beam forming are linear consistent;
the step b comprises the following steps:
and correcting the pre-stored beamforming weights of the rest of the PA channels by utilizing an analog multiplier and/or an analog divider according to the output signal of the reference PA channel and the output of the rest of the PA channels at the same moment in the wireless radio frequency channel.
2. The method of claim 1, wherein the step b comprises:
delaying the reference PA channel to synchronize with each of the rest PA channels in the wireless radio frequency channel;
wherein the step c comprises:
and carrying out beam forming on the wireless radio frequency channel according to the delayed beam forming weight of the reference PA channel and the corrected beam forming weight of the rest PA channels.
3. The method according to claim 1 or 2, wherein the method comprises:
and equally dividing the input signal to obtain a plurality of wireless radio frequency channels, wherein the power value of each wireless radio frequency channel is the same.
4. The method according to claim 1 or 2, wherein said step b comprises:
obtaining pre-stored beam forming weights of the rest PA channels in the wireless radio frequency channels from an original codebook;
and correcting the pre-stored beam forming weight of each other PA channel according to the output signal of the reference PA channel and each output signal of each other PA channel in the wireless radio frequency channel at the same moment.
5. A processing apparatus for performing digital predistortion processing in beamforming, wherein the processing apparatus comprises:
the selection device is used for selecting a reference PA channel from wireless radio frequency channels corresponding to beam forming and carrying out digital pre-distortion processing on the reference PA channel;
the correcting device is used for correcting the beam forming weight prestored in each of the rest of PA channels according to the output signal of the reference PA channel and each output signal of each of the rest of PA channels in the wireless radio frequency channel at the same moment;
the execution device is used for executing beam forming on the wireless radio frequency channel according to the beam forming weight of the reference PA channel and the beam forming weight after the modification of the rest PA channels;
wherein, the antenna arrays corresponding to the beam forming are linear consistent;
wherein the correction device is configured to:
and correcting the pre-stored beamforming weights of the rest of the PA channels by utilizing an analog multiplier and/or an analog divider according to the output signal of the reference PA channel and the output of the rest of the PA channels at the same moment in the wireless radio frequency channel.
6. The processing apparatus according to claim 5, wherein the correction apparatus is configured to:
performing delay processing on the reference PA channel to enable the reference PA channel to be synchronous with other PA channels in the wireless radio frequency channel;
wherein the execution device is configured to:
and carrying out beam forming on the wireless radio frequency channel according to the delayed beam forming weight of the reference PA channel and the corrected beam forming weight of the rest PA channels.
7. The processing apparatus according to claim 5 or 6, wherein the processing apparatus comprises:
and the equalizing device is used for equalizing the input signals to obtain a plurality of radio frequency channels, wherein the power value of each radio frequency channel is the same.
8. The processing apparatus according to claim 5 or 6, wherein the correction means is configured to:
obtaining pre-stored beam forming weights of the rest PA channels in the wireless radio frequency channels from an original codebook;
and correcting the pre-stored beam forming weight of each other PA channel according to the output signal of the reference PA channel and each output signal of each other PA channel in the wireless radio frequency channel at the same moment.
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| PCT/CN2017/110447 WO2019090693A1 (en) | 2017-11-10 | 2017-11-10 | Method and device for performing digital pre-distortion processing during beam forming |
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| CN111740786B (en) * | 2020-06-10 | 2022-01-25 | 电子科技大学 | Integrated optical waveguide beam forming device |
| CN111884694B (en) * | 2020-07-28 | 2023-03-24 | 中国联合网络通信集团有限公司 | Beam forming control method and device, electronic equipment and storage medium |
| CN113131976A (en) * | 2021-03-11 | 2021-07-16 | 西安电子科技大学 | Decimetric wave mixed beam forming method, system and application |
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| CN102570064B (en) * | 2011-12-31 | 2016-08-24 | 南京中兴软件有限责任公司 | Active antenna device and the method for receiving and transmitting signal thereof |
| KR101975830B1 (en) * | 2013-04-02 | 2019-05-09 | 한국전자통신연구원 | Beam forming device and method for forming beam thereof |
| CN103368628B (en) * | 2013-07-18 | 2017-05-03 | 西安科技大学 | Double-current beam forming method based on code books in TD-LTE system |
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| CN105450184A (en) * | 2014-08-08 | 2016-03-30 | 瑞昱半导体股份有限公司 | Digit pre-distortion circuit and method and digit pre-distortion training circuit |
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