CN103379066B - Base station and carry out the method for pre-distortion based on this base station - Google Patents
Base station and carry out the method for pre-distortion based on this base station Download PDFInfo
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Abstract
The invention discloses a kind of base station and carry out the method for pre-distortion based on this base station, wherein, this base station comprises: processor, memory cell and transmitting chain, and wherein, memory cell, for storing pre-distortion coefficients table; Processor, is connected with memory cell and transmitting chain, and for obtaining the pre-distortion coefficients of needs from pre-distortion coefficients table, wherein, the baseband signal that pre-distortion coefficients is used for transmitting chain is launched carries out pre-distortion.This base station can also comprise switch couples module, is connected by transmitting chain with receiver, for obtaining the power amplification distortion signal under different temperatures in the high temperature ageing process of base station, to generate pre-distortion coefficients table.The invention solves the base station circuitry complexity needing independent predistortion feedback path to cause to improve output linearity index, or the technical problem that the efficiency adopting high power power tube to bring is lower, reaches the technique effect simplifying circuit structure, reduce circuit power consumption.
Description
Technical Field
The invention relates to the field of communication, in particular to a base station and a method for carrying out predistortion processing based on the base station.
Background
At present, the micro base station is widely applied and mainly used for solving the problems of outdoor compensation and heat supplement requirements, indoor coverage of public places and enterprises and indoor coverage of home users. The base station of the miniature base station series mainly comprises: micro (Micro base station), Pico (Pico base station) and Femto (Femto Micro base station), the rated output power of these Micro base stations is generally less than 38dBm (6.3W), compared with macro base station, Micro base station has advantages of small volume, light weight, easy installation and low cost.
The output power of the micro base station is limited by the 1db compression point of the radio frequency power amplifier tube (PA for short), the nonlinear characteristic of the power amplifier tube seriously affects the downlink index output by the base station, and the nonlinear characteristic of the amplifier changes along with the change of temperature, so the power amplifier tube (PA for short) becomes a bottleneck problem affecting the downlink index of the micro base station. In order to save cost and reduce volume, the micro base station generally does not adopt a dedicated predistortion feedback channel similar to a macro base station as shown in fig. 1 to improve the output linearity index, but adopts a power amplifier tube (HPA) with a 1dB compression point higher than the output power peak value as shown in fig. 2 to improve the index. However, this method has a problem that the power amplifier consumes most of the power of the whole base station and is inefficient. For example, the peak power of the 3G signal is generally higher than the average value by about 10dB, the 1dB compression point of the power amplifier tube needs to be higher than the average value by more than 10dB to meet the index requirement of output linearity, and if a 24dbm (250mw) signal needs to be output, at least 34dbm (2W) power amplifier tube needs to be selected. However, the high-power amplifier tube is expensive and has high power consumption, an independent heat dissipation measure needs to be added, and the power supply voltage is increased, which does not meet the characteristics of small volume and low power consumption of the micro base station, so that the high-power amplifier tube is difficult to be well applied to the micro base station.
In view of the above problems, no effective solution has been proposed.
Disclosure of Invention
The embodiment of the invention provides a base station and a method for carrying out predistortion processing based on the base station, which at least solve the technical problems that in the prior art, in order to improve the output linear index, a separate predistortion feedback channel is required to carry out predistortion processing, so that the circuit of the base station is complex, or the efficiency is low due to the adoption of a high-power amplifier tube.
According to an aspect of the embodiments of the present invention, there is provided a base station, including: the device comprises a processor, a storage unit and a transmitting link, wherein the storage unit is used for storing a predistortion coefficient table; and the processor is connected with the storage unit and the transmitting link and used for acquiring a needed predistortion coefficient from the predistortion coefficient table, wherein the predistortion coefficient is used for carrying out predistortion processing on a baseband signal transmitted by the transmitting link.
Preferably, the base station further comprises: the receiving link and the switch coupling module are connected, wherein the switch coupling module is connected with the transmitting link and the receiving link, and the switch coupling module is used for connecting the transmitting link and the receiving link under the condition that the switch coupling module is in a first working state; under the condition that the switch coupling module is in a second working state, the switch coupling module disconnects the transmission link and the receiving link; the transmitting link is also used for transmitting a predistortion training signal, wherein the predistortion training signal is a baseband signal generated by a baseband unit of the transmitting link; the receiving link is also used for receiving the power amplifier distortion coupling signal coupled by the switch coupling module, and performing down-conversion and digital sampling on the power amplifier distortion coupling signal to obtain a sampling signal, wherein the power amplifier distortion coupling signal is a signal obtained after a pre-distortion training signal passes through a power amplifier; and the storage unit is also used for storing a predistortion training signal and a sampling signal obtained by sampling the power amplifier distortion coupling signal, wherein the predistortion training signal and the sampling signal are used for generating a predistortion coefficient table.
Preferably, the predistortion training signal and the sampling signal in the storage unit are used for generating a predistortion coefficient table by an external device, and the storage unit is used for storing the predistortion coefficient table obtained from the external device.
Preferably, the external device is a processing device provided with a predistortion processing algorithm program, wherein the predistortion algorithm program is used for generating a predistortion coefficient table according to the predistortion training signal and the sampling signal.
Preferably, the processor is further configured to determine a current operating temperature and an operating frequency point of the power amplifier, and acquire a required predistortion coefficient from the predistortion coefficient table according to the determined operating temperature and the determined operating frequency point.
According to another aspect of the embodiments of the present invention, there is provided a method for performing predistortion processing based on the base station, including: the base station acquires a needed predistortion coefficient from a predistortion coefficient table stored by the base station; and the base station performs predistortion processing on the transmitted baseband signal according to the predistortion coefficient.
Preferably, the base station obtains the required predistortion coefficient from its own stored predistortion coefficient table, including: the base station determines the current temperature grade and/or the current working frequency point; and the base station acquires the predistortion coefficient corresponding to the current temperature grade and/or the current working frequency point from the predistortion coefficient table.
Preferably, the method further comprises: a transmitting link in a base station transmits a predistortion training signal and stores the predistortion training signal in a memory; the power amplifier distortion coupling signal is a signal which is coupled to a receiving link by a switch coupling module after a predistortion training signal passes through a transmitting link, wherein the predistortion training signal and the sampling signal are used for generating a predistortion coefficient table.
Preferably, the transmitting link in the base station transmits the pre-distorted training signal and stores the pre-distorted training signal in the memory, including: determining different temperature levels of the base station; in the process of carrying out high-temperature aging on the base station, the base station transmits a predistortion training signal at the temperature corresponding to each temperature grade, and stores the predistortion training signal corresponding to each temperature grade in a memory; the method for sampling the power amplifier distortion coupling signal by a receiving link in a base station to obtain a sampling signal comprises the following steps: and the receiving link samples the power amplifier distortion coupling signal to obtain a sampling signal corresponding to each temperature grade, and stores the sampling signal into a memory.
Preferably, the transmitting link in the base station transmits the pre-distorted training signal and stores the pre-distorted training signal in the memory, including: setting different working frequency points; the transmission link transmits a predistortion training signal corresponding to each working frequency point and stores the predistortion training signal into a memory; the method for sampling the power amplifier distortion coupling signal by a receiving link in a base station to obtain a sampling signal comprises the following steps: and the receiving link samples the power amplifier distortion coupling signal to obtain a sampling signal corresponding to each working frequency point, and stores the sampling signal into a memory.
Preferably, after saving the sampling signal into the memory, the method further comprises: the base station sends the pre-distortion training signal and the sampling signal to external equipment; and the base station receives a predistortion coefficient table which is generated by the external equipment according to the predistortion training signal and the sampling signal and corresponds to different temperature grades and/or different working frequency points.
Preferably, the external device generates a predistortion coefficient table corresponding to different temperature levels and/or different working frequency points according to the predistortion training signal and the sampling signal, and the table includes: the external equipment receives a predistortion training signal and a sampling signal sent by a base station; the external equipment generates a predistortion coefficient table by utilizing a predistortion algorithm program set by the external equipment according to the predistortion training signal and the sampling signal; the external device transmits the table of predistortion coefficients to the base station.
Preferably, after the base station receives a predistortion coefficient table corresponding to different temperature levels and/or different operating frequency points generated by an external device according to the predistortion training signal and the sampling signal, the method further includes: the base station detects the predistortion coefficient table; and when the detection result does not meet the preset condition, the base station generates the predistortion training signal again, samples the power amplifier distortion coupling signal corresponding to the predistortion training signal and generates a new predistortion coefficient table.
In the embodiment of the invention, the processor acquires the needed predistortion coefficient from the predistortion coefficient table stored in the base station, performs predistortion processing on the baseband signal according to the predistortion coefficient, and then obtains an output linear signal through the distortion of the power amplifier, thereby improving the linear performance of the base station. Through the mode, the base station stores the predistortion coefficient, and does not need a special predistortion feedback channel, so that the circuit complexity of the base station is reduced, the technical problem that the circuit of the base station is complex due to the fact that the independent predistortion feedback channel is needed to carry out real-time predistortion processing in the prior art is solved, and the technical effects of simplifying the circuit structure and reducing the circuit power consumption are achieved.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the invention without limiting the invention. In the drawings:
fig. 1 is a schematic structural diagram of a base station in which a dedicated predistortion feedback channel exists according to the related art;
fig. 2 is a schematic structural diagram of a base station in which a power amplifier tube having a compression point of 1dB higher than a peak value of output power exists according to the related art;
fig. 3 is a block diagram of a preferred structure of a base station according to an embodiment of the present invention;
FIG. 4 is a block diagram of another preferred structure of a base station according to an embodiment of the present invention;
FIG. 5 is a preferred flow chart of pre-distortion processing of a base band signal of a base station in accordance with an embodiment of the present invention;
fig. 6 is a preferred flow chart for obtaining a table of predistortion coefficients according to an embodiment of the present invention;
FIG. 7 is a preferred flow chart of a method of sampling signals at different temperature levels in accordance with an embodiment of the present invention;
fig. 8 is a preferred flowchart of a method for sampling signals at different operating frequencies according to an embodiment of the present invention;
fig. 9 is a schematic diagram of a preferred structure of a base station according to an embodiment of the present invention;
fig. 10 is another preferred flowchart of a processing method of a baseband signal according to an embodiment of the present invention;
fig. 11 is a preferred flow chart of the production flow of the base station on the production line according to the embodiment of the present invention.
Detailed Description
The invention will be described in detail hereinafter with reference to the accompanying drawings in conjunction with embodiments. It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict.
The present embodiment provides a base station, as shown in fig. 3, the base station includes: the device comprises a processor 302, a storage unit 304 and a transmission chain 306, wherein the storage unit 302 is used for storing a predistortion coefficient table; and the processor 304 is connected with the storage unit 304 and the transmission link 306, and is configured to obtain a required predistortion coefficient from the predistortion coefficient table, where the predistortion coefficient is used to perform predistortion processing on a baseband signal transmitted by the transmission link.
In the preferred embodiment, the processor obtains the required predistortion coefficient from the predistortion coefficient table stored in the base station itself, and performs predistortion processing on the baseband signal according to the predistortion coefficient, thereby improving the linear performance of the base station. Through the mode, the base station stores the predistortion coefficient table, and does not need a special predistortion feedback channel, so that the circuit complexity of the base station is reduced, the technical problems that in the prior art, the circuit of the base station is complex due to the fact that an independent predistortion feedback channel is needed for predistortion treatment in order to improve the output linear index, or the efficiency is low due to the fact that a high-power amplifier tube is adopted are solved, and the technical effects of simplifying the circuit structure and reducing the circuit power consumption are achieved.
In a preferred embodiment, in order to generate a table of predistortion coefficients corresponding to the base station, a switch coupling module is disposed between a transmission link and a reception link of the base station, as shown in fig. 4, the base station further includes: a receiving link 402 and a switch coupling module 404, wherein the switch coupling module 402 is connected to the transmitting link 306 and the receiving link 402, and the switch coupling module 402 connects the transmitting link 306 and the receiving link 402 when the switch coupling module 404 is in a first working state; that is, in the case that the switch coupling module 404 is in the first operating state, the switch coupling module 402 couples the signal transmitted by the transmitting link 306 to the receiving link 402; under the condition that the switch coupling module 402 is in the second working state, the switch coupling module 402 disconnects the transmission link 306 and the receiving link 402; the transmitting link is also used for transmitting a predistortion training signal; the receiving link 402 is further configured to receive a power amplifier distortion coupling signal through the switch coupling module 402, where the power amplifier distortion coupling signal is a signal obtained by passing a predistortion training signal through a power amplifier; the storage unit 302 is further configured to store a predistortion training signal and a sampling signal obtained by sampling the power amplifier distortion coupling signal, where the predistortion training signal and the sampling signal are used to generate a predistortion coefficient table.
Specifically, the switch coupling module 404 includes: the power detection circuit comprises a first switch and a second switch, wherein the input end of the first switch is connected with a transmitting link through a coupler, and the first output end of the first switch is connected with a power detection module; the first input end of the second switch is connected with the second output end of the first switch; the second input end of the second switch is connected with the duplexer, and the output end of the second switch is connected with the receiving link. When the input end of the first switch is connected with the second output end of the first switch and the first input end of the second switch is connected with the output end of the second switch, the switch coupling module is in a first working state; when the input end of the first switch is connected with the first output end of the first switch and the second input end of the second switch is connected with the output end of the second switch, the switch coupling module is in a second working state. When the switch coupling module is in a first working state, the switch coupling module couples the signal amplified by the power amplifier of the transmitting link to the receiving link, and samples the signal through the receiving link to obtain predistortion signal data corresponding to the base station, so as to generate a corresponding predistortion coefficient table. Preferably, in order to fully utilize the high temperature aging process, the switch coupling module may be in the first operating state during the high temperature aging process of the base station, so as to obtain the pre-distortion training signal and the sampling signal corresponding to the base station at different temperature levels.
In the above preferred embodiment, a switch coupling module is added between the receiving link and the transmitting link, the switch coupling module couples the predistortion training signal transmitted by the transmitting link to the receiving link, and in the process, stores the baseband predistortion training signal transmitted by the transmitting link and the sampling signal obtained by sampling the power amplifier distortion coupling signal corresponding to the predistortion training signal after passing through the power amplifier, and processes the predistortion training signal and the sampling signal through an external device to generate a predistortion coefficient table, so that the base station can call the predistortion coefficient table corresponding to the base station to perform predistortion processing in the actual working process, thereby improving the linear index of the base station.
The predistortion coefficient table may be generated in an external device, the base station itself only needs to provide a corresponding predistortion training signal and a corresponding sampling signal, and transmit the predistortion training signal and the sampling signal to an external processing device (e.g., a computer), the external device is configured with a predistortion processing algorithm program, after obtaining the predistortion training signal and the sampling signal, the external device generates a predistortion coefficient table corresponding to the base station according to the predistortion training signal and the sampling signal, and then uploads the predistortion coefficient table to the base station, a storage unit in the base station stores the predistortion coefficient table for calling when transmitting a signal, and the storage unit in the base station may be a flash memory. In a preferred embodiment, the predistortion training signal and the sampling signal in the storage unit are used for generating a predistortion coefficient table by an external device, and the storage unit is used for storing the predistortion coefficient table obtained from the external device.
In a preferred embodiment, the external device is a processing device provided with a predistortion processing algorithm program, wherein the predistortion algorithm program is used for generating a predistortion coefficient table according to a predistortion training signal and a sampling signal. In the working process of the base station, the base station may correspond to different working frequency points, and the power amplifier may also have different temperature levels, so that the predistortion coefficient table records the predistortion coefficients of the base station at different temperature levels and different working frequency points, preferably, each temperature level corresponds to one predistortion coefficient table, and the predistortion coefficient table records the predistortion coefficients required to be adopted by different working frequency points at the temperature level. In a preferred embodiment, the processor is further configured to determine a current operating temperature and an operating frequency point of the power amplifier, and obtain a required predistortion coefficient from the predistortion coefficient table according to the determined operating temperature and the operating frequency point.
As used in connection with the above-described base station, the term "module" or "unit" may be a combination of software and/or hardware that implements a predetermined function, and implementations of software, hardware, or a combination of software and hardware are also possible and contemplated.
Based on the foregoing base station, this embodiment further provides a method for performing predistortion processing, as shown in fig. 5, where the method includes the following steps:
step S502: the base station acquires a needed predistortion coefficient from a predistortion coefficient table stored by the base station;
step S504: and the base station performs predistortion processing on the transmitted baseband signal according to the predistortion coefficient.
In the preferred embodiment, the base station obtains a pre-distortion coefficient table stored in the base station, obtains a required pre-distortion coefficient from the pre-distortion coefficient table, performs pre-distortion processing on a baseband signal according to the pre-distortion coefficient, and obtains an improved output signal through distortion of a power amplifier, thereby improving the linear performance of the base station. Through the mode, the base station stores the predistortion coefficient, a special predistortion feedback channel is not needed, the circuit complexity of the base station is reduced, the technical problems that in the prior art, in order to improve the output linear index, the base station circuit is complex due to the fact that an independent predistortion feedback channel is needed to carry out predistortion processing, or the efficiency is low due to the fact that a high-power amplifier tube is adopted are solved, and the technical effects of simplifying the circuit structure and reducing the circuit power consumption are achieved.
In the working process of the base station, the base station corresponds to different working frequency points, and the power amplifier also has different temperature grades, so that the predistortion coefficient table records the predistortion coefficients which are required to be sampled by the base station at different temperature grades and different working frequency points, preferably, each temperature grade corresponds to one predistortion coefficient table, and the predistortion coefficient table records the predistortion coefficients required to be adopted by different working frequency points at the temperature grade. In a preferred embodiment, the base station obtains a required predistortion coefficient from a predistortion coefficient table stored in the base station, and the method includes: the base station determines the current temperature grade and/or the current working frequency point; and the base station acquires the predistortion coefficient corresponding to the current temperature grade and/or the current working frequency point from the predistortion coefficient table.
In a preferred embodiment, there is provided a method for a base station to obtain its corresponding table of predistortion coefficients, as shown in fig. 6, the method includes the following steps:
step S602: a transmitting link in a base station transmits a predistortion training signal and stores the predistortion training signal in a memory;
step S604: a receiving link in a base station samples the power amplifier distortion coupling signal to obtain a sampling signal;
in step S604, the power amplifier distortion coupling signal is a signal that is obtained by coupling a pre-distortion training signal to a receiving link through a transmitting link by a switch coupling module, where the pre-distortion training signal and the sampling signal are used to generate a pre-distortion coefficient table. In practical application, when receiving a power amplifier distortion coupling signal passing through a switch coupling module, a receiving link needs to perform down-conversion processing on the signal first, and digital sampling is performed on down-converted data to obtain a sampling signal.
Step S606: the base station sends the pre-distortion training signal and the sampling signal to external equipment;
step S608: and the base station receives a predistortion coefficient table which is generated by the external equipment according to the predistortion training signal and the sampling signal and corresponds to different temperature grades and/or different working frequency points.
Considering that the base station needs to know predistortion coefficients required to be adopted at different working frequency points and/or different temperature grades, when the predistortion coefficients are generated, sampling signals for generating the predistortion coefficients corresponding to the sampling signals can be selected in the process of carrying out high-temperature aging on the base station, and the base station needs to pass through the processes of different temperature grades such as normal temperature, secondary high temperature and high temperature corresponding to the high-temperature aging process, so that predistortion training signals and sampling signals of the base station at different temperature grades can be obtained in the high-temperature aging process, and the predistortion coefficients at different temperature grades can be generated. Different working frequency points can be set in the process to obtain predistortion coefficients corresponding to the different working frequency points.
To achieve the above object, in a preferred embodiment, there is provided a method of sampling signals of different temperature levels, as shown in fig. 7, the method comprising the steps of:
step S702: determining different temperature levels of the base station;
step S704: in the process of carrying out high-temperature aging on the base station, the base station transmits a predistortion training signal at the temperature corresponding to each temperature grade, and stores the predistortion training signal corresponding to each temperature grade in a memory;
step S706: and the receiving link samples the power amplifier distortion coupling signal to obtain a sampling signal corresponding to each temperature grade, and stores the sampling signal into a memory.
In another preferred embodiment, a method for sampling signals at different operating frequency points is provided, as shown in fig. 8, the method includes the following steps:
step S802: setting different working frequency points;
step S804: the transmission link transmits a predistortion training signal corresponding to each working frequency point and stores the predistortion training signal into a memory;
step S806: and the receiving link samples the power amplifier distortion coupling signal to obtain a sampling signal corresponding to each working frequency point, and stores the sampling signal into a memory.
Through the preferred embodiment, the predistortion coefficients corresponding to different temperature levels and different working frequency points of the base station can be obtained. Because the high-temperature aging process is a process in which the temperature gradually increases, when the sampling signal is obtained, different working frequency points can be set at the temperature grade when the corresponding temperature grade is reached, so as to obtain the sampling signal corresponding to the temperature grade at different working frequency points. In each temperature grade, the above manner is sampled, and then the sampling signals corresponding to different working frequency points in each temperature grade can be obtained. By the mode, each temperature grade and the predistortion coefficient corresponding to each working frequency point under the temperature grade are ensured in the predistortion coefficient table.
The external device in step S608 generates a predistortion coefficient table corresponding to different temperature levels and/or different operating frequency points according to the following steps based on the predistortion training signal and the sampling signal: the external equipment receives a predistortion training signal and a sampling signal sent by a base station; the external equipment generates a predistortion coefficient table by utilizing a predistortion algorithm program set by the external equipment according to the predistortion training signal and the sampling signal; the external device transmits the table of predistortion coefficients to the base station.
In order to ensure the effectiveness of the predistortion coefficient table, after the predistortion coefficient table is obtained, the predistortion coefficient table may be verified, if the predistortion coefficient table is qualified, the predistortion coefficient table is used as the predistortion coefficient table called when the base station works, and if the detection is not qualified, sampling is performed again to regenerate the predistortion coefficient table, in a preferred embodiment, after the base station receives the predistortion coefficient table corresponding to different temperature levels and/or different working frequency points generated by the external device according to the predistortion training signal and the sampling signal, the method further includes: the base station detects the predistortion coefficient table; and when the detection result does not meet the preset condition, the base station generates the pre-distortion training signal again and samples the power amplifier distortion coupling signal corresponding to the pre-distortion training signal.
Reference will now be made in detail to the preferred embodiments, which combine the above embodiments and their preferred embodiments.
In this embodiment, a femtocell transceiver link is provided, as shown in fig. 9, a switch coupling module is added between a receiving channel (i.e., the receiving link in the above) and a transmitting channel (i.e., the transmitting link in the above). The digital sampling function of a receiving channel is utilized, distortion signals of a power amplifier at different temperatures are collected in the high-temperature aging process of a base station, a predistortion coefficient table is generated by combining the algorithm processing of a computer at a wireless index station, the predistortion coefficient table is provided for a miniature base station to perform predistortion processing on baseband signals, a CPU (central processing unit) controls and calls the predistortion coefficient table to perform predistortion on the baseband signals, and the linear index of output signals of the power amplifier is improved. Therefore, the purposes of improving the linear index output by the base station, improving the efficiency of the whole machine and reducing the cost and the volume are achieved. By the mode, the problems that in the prior art, the efficiency of improving the compression point of the power amplifier is low and the cost is high due to the adoption of a special pre-distortion channel are solved, and the problem that the linear index of the micro base station is deteriorated due to the temperature change characteristic of the power amplifier tube at different temperatures is also solved.
In the process of performing high-temperature aging on the base station, at different temperatures, a test signal generation module (TSG) sends out a downlink baseband signal, Digital-to-analog converter (DAC) and an intermediate frequency and radio frequency module complete Digital-to-analog conversion, modulation and amplification of the signal, the radio frequency switches 1 and 2 (i.e. Switch1 and Switch2 in fig. 9) between transmitting and receiving are controlled by the software control module, so that the Switch coupling module is in the first working state, thereby directly coupling the transmitting link signal to the receiving link, setting the local oscillation frequency point of the receiving link, and performing down-conversion and ADC digital sampling processing on the power amplifier distortion coupling signal to obtain a zero-frequency sampling signal, and finally storing the sampling signal data of the TSG baseband source signal and the power amplifier distortion coupling signal in a base station flash memory (flash).
Downloading data stored in a base station flash to a computer locally, analyzing and processing data information downloaded by the base station by utilizing a predistortion algorithm program to obtain a predistortion coefficient table corresponding to the base station, uploading and storing the predistortion coefficient table in the base station flash, carrying out predistortion processing on an output baseband signal when the base station normally works, and finally outputting an improved linear signal through distortion of a power amplifier.
After the high temperature treatment, testing SEM (spectrum radiation template) and ACPR (adjacent channel power ratio) indexes of the base station by using a frequency spectrograph on a wireless index testing station, entering the next station after the base station passes the verification, and if the base station does not pass the verification, performing data acquisition and predistortion treatment again.
In order to illustrate the embodiments of the present invention more clearly, the present invention is further described below in a specific embodiment.
In this embodiment, a 2.1G-band Wideband Code Division Multiple Access (WCDMA) pico base station (antenna port power is 24dBm) is taken as an example, and details of a hardware design idea, a technical scheme, and implementation steps are described in detail with reference to the drawings.
When a base station transceiving link is designed, a switch coupling module is required to be added on hardware, the switch coupling module is physically connected with a transmitting channel and a receiving channel, the transmitting channel transmits a TSG training signal, the switch coupling module is controlled through software, a distortion signal passing through a power amplifier is coupled to the receiving channel, the receiving channel is used for sampling the signal, then the sampling signal is downloaded to a computer for predistortion analysis processing, a predistortion coefficient table is generated, and finally the predistortion coefficient table is uploaded to the base station for use.
A specific flow of signal processing based on the base station shown in fig. 9 is shown in fig. 10, and includes the following steps:
step S1002: the local transmitting and receiving frequency points corresponding to the frequency points of the transmitted signals are set to be 2110MHz, (namely the working frequency points above), for a zero intermediate frequency transceiver, only the local transmitting and receiving frequency points are set to be 2110MHz, and for a non-zero intermediate frequency transceiver, only the local transmitting and receiving frequency points corresponding to the 2110MHz radio frequency are calculated and set respectively.
Step S1004: and controlling a digital transmitting chip to send out a TSG full-power signal (24dBm), namely a signal used for digital predistortion training, storing the TSG baseband source signal into a flash, and preferably, naming the baseband source signal as TSGBBSourceData.
Step S1006: and controlling to turn on the radio frequency switches 1 and 2 for transmitting to the receiver so that the output signal of the power amplifier can be coupled to the receiving channel. When the above-mentioned base station circuit is designed, it needs to be ensured that the power amplifier coupling signal is amplified by the receiving channel and then falls within the sampling range of the Analog-to-digital converter (ADC for short) during the predistortion processing, and it needs to be ensured that the signal output by the transmitting link does not affect the uplink index when the base station normally works.
The embodiment can ensure that the coupling signal is free from distortion after being amplified by the receiving channel and falls into the proper sampling range of the ADC in the aspect of hardware design. Taking the incoming ADC signal as-12 dBFs, full range FS of ADCadcAt 0dBm, a Variable Gain Amplifier (VGA) gain is set so that the receive channel gain is GrxThe explanation is given by taking 4dB as an example. Considering insertion loss of circulator and duplexer as 3dB, power amplifier outputs signal power PPAoutAt 27dBm, 24+3, the total coupling is C, considering a coupler coupling of 40dB, two rf switches and a path loss of 3dBoup40+ 3-43 dB, the power P entering the ADC portadcin＝PPAout-Coup+Grx27-43+ 4-12 dBm. However, the base station needs to ensure that the transmission signal has no effect on the received signal when the switch is turned off: taking a Wideband Code Division Multiple Access (WCDMA) base station as an example for analysis, the thermal noise is low-108 dBm/3.84MHz, the receiving front end is low in noise and has a gain of 30dB, and the noise coefficient is 2dB, so that the thermal noise entering the transmitting and receiving connection point is-108 dBm +30dB +2 dB-76 dBm, and the receiving index of the base station is not affected as long as the power leaked to the connection point when the base station is transmitted at full power is less than the thermal noise by more than 10 dB. The rf switch has an Isolation of 40dB (in this design, two rf switches are provided, which can ensure an Isolation of 80 dB), and the coupler has a coupling of 40dB, so that the Isolation from transmission to reception is 2 × 40dB +40dB — 120dB in normal operation. Transmit signal power P leaked to receive channelTxtoRx27dBm-120 dB-93 dBm is much smaller than-76 dBm, so that the receiving index is not affected when the base station works normally.
Step S1008: the ADC performs digital sampling on the power amplifier distortion coupling signal, and stores the sampled data in the flash of the base station, preferably, the data is named PADistortiondata.
Step S1010: the digital predistortion training signal data PADistorInDataData and TSGBBSourceDataData in the base station flash are downloaded to the local by an external processing device (which can be a computer), the training signals are analyzed and processed by a predistortion algorithm program, so that a predistortion coefficient table corresponding to the base station is generated, and the table is stored as DpdCoefTable.
Step S1012: and preferably, a Central Processing Unit (CPU) controls and calls the predistortion coefficient table to perform predistortion of baseband signals, so that the linear index of the power amplifier output signals is improved.
Step S1014: after the training of one transmitting frequency point (working frequency point) is completed, the training process of a new working frequency point is restarted and set, for example, the training process is traversed once from 2110MHz to 2170MHz by 1MHz step by step to obtain the predistortion coefficients of all frequency points, and the table is stored in a base station flash for calling when the base station works at different frequency points under the temperature.
Step S1016: after all the frequency points are completed, the switch is set to the original default state (i.e., the second working state above, which is also the working state in fig. 9), and the normal working state of the base station is recovered.
The embodiment further provides a production flow of the base station on a production line, as shown in fig. 11, the specific steps include:
step S1102: after the production calibration of the production line, the base station is sent to a high temperature aging environment, and preferably, the high temperature aging is kept for 24 hours.
Step S1104: at normal temperature, sub-high temperature and high temperature, respectively using software to control the base station to sample to obtain pre-distortion training signal data of different frequency points, wherein the pre-distortion training signal data comprises a baseband source signal and a power amplifier distortion signal (namely the power amplifier distortion coupling signal) and is stored in the base station flash.
Step S1106: after the base station is aged at high temperature, the qualified base station is screened out and sent to a predistortion processing station (which can also be finished at a wireless index station), predistortion training signal data are downloaded to a computer, predistortion algorithm analysis processing is carried out, a predistortion coefficient table corresponding to the base station is obtained, and the predistortion coefficient table is uploaded to a base station flash. Therefore, the base station stores the predistortion coefficient tables of normal temperature, sub-high temperature and high temperature under different frequency points, and the base station calls the predistortion coefficient tables to perform distortion processing on baseband signals when working at different temperature levels and different frequency points.
Step S1108: the base station predistortion processing function is verified and tested by using a frequency spectrograph, and SEM (spectrum radiation template) and ACPR (adjacent channel power ratio) indexes of the base station at low frequency point, medium frequency point and high frequency point (for example, 2115M, 2140M and 2165MHz) are tested at normal temperature.
Step S1110: and after the verification is passed, the base station enters the next station, if the verification is not passed, repair positioning is carried out, failure reasons are analyzed, and whether the base station is qualified or not is determined. Preferably, if the verification fails, the data acquisition and pre-distortion processing can be performed again.
Preferably, the processing procedures in step S1106 and step S1108 may also be performed at the wireless index station, a computer at the wireless index station is used to process the sampling signal to obtain a predistortion coefficient table and upload the table, and meanwhile, a wireless index station instrument test is also used to verify the index.
In the above preferred embodiments and examples, only the normal temperature and high temperature data are obtained, because at low temperature, the performance of the radio frequency electronic device will be improved, the radio frequency linear index is improved, and it is only necessary to generate the predistortion coefficient table without low temperature data acquisition and call the normal temperature predistortion coefficient table for use.
In this embodiment, the base station obtains a pre-distortion coefficient table stored in the base station itself, obtains a required pre-distortion coefficient from the pre-distortion coefficient table, performs pre-distortion processing on a baseband signal according to the pre-distortion coefficient, and obtains a linear output signal through distortion of a power amplifier, thereby improving the linear performance of the base station. Through the mode, the base station stores the predistortion coefficient, a special predistortion feedback channel is not needed, the circuit complexity of the base station is reduced, the technical problem that in the prior art, the circuit complexity of the base station is caused by the fact that the independent predistortion feedback channel is needed to carry out real-time predistortion processing is solved, and the technical effects of simplifying the circuit structure and reducing the circuit power consumption are achieved.
The methods according to the above preferred embodiments of the present invention can be applied to all base stations, for example, macro base stations, micro base stations, and the like. Especially, the application effect in the micro base station is best.
In another embodiment, a software is provided, which is used to execute the technical solutions described in the above embodiments and preferred embodiments.
In another embodiment, a storage medium is provided, in which the software is stored, and the storage medium includes but is not limited to: optical disks, floppy disks, hard disks, erasable memory, etc.
It will be apparent to those skilled in the art that the modules or steps of the present invention described above may be implemented by a general purpose computing device, they may be centralized on a single computing device or distributed across a network of multiple computing devices, and alternatively, they may be implemented by program code executable by a computing device, such that they may be stored in a storage device and executed by a computing device, and in some cases, the steps shown or described may be performed in an order different than that described herein, or they may be separately fabricated into individual integrated circuit modules, or multiple ones of them may be fabricated into a single integrated circuit module. Thus, the present invention is not limited to any specific combination of hardware and software.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (11)
1. A base station, comprising: a processor, a memory unit, and a transmit chain, wherein,
the storage unit is used for storing a predistortion coefficient table;
the processor is connected with the storage unit and the transmission link, and is configured to acquire a required predistortion coefficient from the predistortion coefficient table, where the predistortion coefficient is used to perform predistortion processing on a baseband signal transmitted by the transmission link;
wherein,
the base station further comprises: the receiving link and the switch coupling module are connected, and the switch coupling module is connected with the transmitting link and the receiving link and is used for connecting the transmitting link and the receiving link under the condition that the switch coupling module is in a first working state; under the condition that the switch coupling module is in a second working state, the switch coupling module disconnects the transmission link and the receiving link;
the transmitting link is further configured to transmit a predistortion training signal, where the predistortion training signal is a baseband signal generated by a baseband unit of the transmitting link; the receiving link is further configured to receive a power amplifier distortion coupling signal coupled by the switch coupling module, and perform down-conversion and digital sampling on the power amplifier distortion coupling signal to obtain a sampling signal, where the power amplifier distortion coupling signal is a signal obtained after the pre-distortion training signal passes through a power amplifier;
the storage unit is further configured to store a predistortion training signal and a sampling signal obtained by sampling the power amplifier distortion coupling signal, where the predistortion training signal and the sampling signal are used to generate the predistortion coefficient table.
2. The base station of claim 1, wherein the predistortion training signal and the sampling signal in the storage unit are used to generate the predistortion coefficient table by an external device, and wherein the storage unit is used to store the predistortion coefficient table obtained from the external device.
3. The base station of claim 2, wherein the external device is a processing device provided with a predistortion algorithm program, wherein the predistortion algorithm program is configured to generate the predistortion coefficient table according to the predistortion training signal and the sampling signal.
4. The base station of claim 1, wherein the processor is further configured to determine a current operating temperature and an operating frequency point of the power amplifier, and obtain a required predistortion coefficient from the predistortion coefficient table according to the determined operating temperature and operating frequency point.
5. A method for pre-distortion processing based on the base station of any one of claims 1-4, comprising:
the base station acquires a needed predistortion coefficient from a predistortion coefficient table stored by the base station;
the base station carries out predistortion processing on the transmitted baseband signal according to the predistortion coefficient;
wherein a transmission link in the base station transmits a pre-distortion training signal and stores the pre-distortion training signal in a memory;
the base station comprises a receiving link, a power amplifier distortion coupling signal and a switch coupling module, wherein the receiving link in the base station samples the power amplifier distortion coupling signal to obtain a sampling signal, the power amplifier distortion coupling signal is a signal which is coupled to the receiving link by the switch coupling module after the predistortion training signal passes through a transmitting link, and the predistortion training signal and the sampling signal are used for generating the predistortion coefficient table.
6. The method of claim 5, wherein the base station obtains the required predistortion coefficients from its own stored predistortion coefficient table, and comprises:
the base station determines the current temperature grade and/or the current working frequency point;
and the base station acquires the predistortion coefficient corresponding to the current temperature grade and/or the current working frequency point from the predistortion coefficient table.
7. The method of claim 5,
the transmitting link in the base station transmits a pre-distortion training signal and stores the pre-distortion training signal in a memory, including:
determining different temperature levels of the base station;
in the process of carrying out high-temperature aging on the base station, the base station transmits a predistortion training signal at the temperature corresponding to each temperature grade, and stores the predistortion training signal corresponding to each temperature grade in the memory;
the receiving link in the base station samples the power amplifier distortion coupling signal to obtain a sampling signal, and the method comprises the following steps:
and the receiving link samples the power amplifier distortion coupling signals to obtain sampling signals corresponding to each temperature grade, and stores the sampling signals into a memory.
8. The method according to claim 5 or 7,
the transmitting link in the base station transmits a pre-distortion training signal and stores the pre-distortion training signal in a memory, including:
setting different working frequency points;
the transmitting link transmits a predistortion training signal corresponding to each working frequency point and stores the predistortion training signal into a memory;
the receiving link samples the power amplifier distortion coupling signal to obtain a sampling signal, and the method comprises the following steps:
and the receiving link samples the power amplifier distortion coupling signal corresponding to the predistortion training signal of each working frequency point to obtain a sampling signal corresponding to each working frequency point, and stores the sampling signal in a memory.
9. The method of claim 8, further comprising, after saving the sampled signal to memory:
the base station sends the pre-distortion training signal and the sampling signal to external equipment;
and the base station receives a predistortion coefficient table which is generated by the external equipment according to the predistortion training signal and the sampling signal and corresponds to different temperature grades and/or different working frequency points.
10. The method according to claim 9, wherein the external device generates a predistortion coefficient table corresponding to different temperature levels and/or different operating frequency points according to the predistortion training signal and the sampling signal, and the method comprises:
the external equipment receives the predistortion training signal and the sampling signal sent by the base station;
the external equipment generates the predistortion coefficient table by utilizing a predistortion algorithm program set by the external equipment according to the predistortion training signal and the sampling signal;
and the external equipment sends the predistortion coefficient table to the base station.
11. The method according to claim 9, wherein after the base station receives a predistortion coefficient table corresponding to different temperature levels and/or different operating frequency points generated by the external device according to the predistortion training signal and the sampling signal, the method further comprises:
the base station detects the predistortion coefficient table;
and when the detection result does not meet the preset condition, the base station generates the predistortion training signal again, samples the power amplifier distortion coupling signal corresponding to the predistortion training signal and generates a new predistortion coefficient table.
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| CN106470017B (en) * | 2015-08-20 | 2020-04-03 | 深圳市中兴微电子技术有限公司 | Predistortion coefficient processing method and device |
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| CN101217522A (en) * | 2007-12-27 | 2008-07-09 | 华为技术有限公司 | A method and device to determine the predistortion parameter of open loop, commutator and commutating method |
| CN101330481A (en) * | 2007-06-19 | 2008-12-24 | 中兴通讯股份有限公司 | Predistortion model apparatus as well as apparatus, system and method for processing predistortion of signal |
| CN101662435A (en) * | 2009-09-24 | 2010-03-03 | 中兴通讯股份有限公司 | Device and method for obtaining and adjusting digit pre-distortion parameters |
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| CN101330481A (en) * | 2007-06-19 | 2008-12-24 | 中兴通讯股份有限公司 | Predistortion model apparatus as well as apparatus, system and method for processing predistortion of signal |
| CN101217522A (en) * | 2007-12-27 | 2008-07-09 | 华为技术有限公司 | A method and device to determine the predistortion parameter of open loop, commutator and commutating method |
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