CN117526987A

CN117526987A - Remote radio unit transformation method, remote radio unit and storage medium

Info

Publication number: CN117526987A
Application number: CN202311443135.0A
Authority: CN
Inventors: 欧阳晖; 徐青云; 陈国洲; 梁发泳; 彭雯婷; 徐伟; 舒雪标
Original assignee: China Telecom Corp Ltd
Current assignee: China Telecom Corp Ltd
Priority date: 2023-11-01
Filing date: 2023-11-01
Publication date: 2024-02-06

Abstract

The application provides a remote radio unit transformation method, a remote radio unit and a storage medium, and belongs to the technical field of data processing. Loading a standard wireless signal and a baseband signal of a target narrowband internet of things into a digital intermediate frequency link containing a target downlink in a target remote radio unit, wherein the target downlink comprises the standard wireless signal downlink and the target narrowband internet of things downlink, and the target narrowband internet of things downlink comprises a digital up-conversion filter, a mixer, a peak clipping device and an open-loop digital predistorter provided with initial parameters; obtaining output information of an output end of a digital intermediate frequency link for verification; and performing closed-loop adjustment on initial parameters of the open-loop digital predistorter according to the verification result until the output information meets the verification, and determining parameters of the finally deployed open-loop digital predistorter. The application aims to provide a narrowband internet of things service by applying RRU equipment of the existing network.

Description

Remote radio unit transformation method, remote radio unit and storage medium

Technical Field

The embodiment of the application relates to the technical field of data processing, in particular to a remote radio unit transformation method, a remote radio unit and a storage medium.

Background

In recent years, the development of the service of the internet of things is rapid, which is an important development direction of the industrialization of operators, and currently, the most widely applied of operators to the terminals of the internet of things for providing services to clients is NB-IoT (Narrow Band Internet of Things ) defined by the 4G (the 4th generation mobile communication technology, fourth generation mobile communication technology) standard, and the network provided by the operators is required to provide coverage and services of the NB-IoT, so that both the baseband of the remote radio unit and the remote radio unit are required to support the NB-IoT system.

The 800M/900M/1.8G/2.1G remote radio units in the wireless mobile data network can provide NB-IoT signals with 180kHz bandwidth, and can provide narrowband internet of things service in a new or improved mode, but the new mode involves a great deal of cost such as equipment purchasing and engineering installation, so how to improve on the existing network remote radio units equipment to introduce NB-IoT carriers with narrow bandwidth and high power density is a problem to be solved urgently.

Disclosure of Invention

The embodiment of the application provides a remote radio unit transformation method, a remote radio unit and a storage medium, and aims to provide a narrowband Internet of things service by using remote radio unit equipment of the existing network.

In a first aspect, an embodiment of the present application provides a method for modifying a remote radio unit of a narrowband internet of things service, where the method includes:

loading a standard wireless signal and a baseband signal of a target narrowband internet of things into a digital intermediate frequency link containing a target downlink in a target remote radio unit, wherein the target downlink comprises the standard wireless signal downlink and the target narrowband internet of things downlink, the target narrowband internet of things downlink comprises a digital up-conversion filter, a mixer, a peak clipping device and an open-loop digital predistorter which are sequentially connected, and the open-loop digital predistorter and the output end of a closed-loop digital predistorter of the standard wireless signal downlink are both connected with a combiner, wherein the open-loop digital predistorter is provided with initial parameters;

obtaining output information of the output end of the digital intermediate frequency link for verification;

and performing closed-loop adjustment on initial parameters of the open-loop digital predistorter according to the verification result of the output information of the output end of the digital intermediate frequency link until the output information of the output end of the digital intermediate frequency link meets the verification, and determining parameters of the finally deployed open-loop digital predistorter.

Optionally, the method further comprises:

according to the model of the remote radio unit and the multiple carrier types of the target narrowband Internet of things, performing simulation training on the working states of the open-loop digital predistorter under different parameters to obtain a first parameter data table of the open-loop digital predistorter, wherein the first parameter data table comprises carrier configurations of different target narrowband Internet of things and parameter values of the open-loop digital predistorter corresponding to different powers and environment temperatures of a power amplifier of the digital intermediate frequency link.

Optionally, performing closed-loop adjustment on the initial parameters of the open-loop digital predistorter according to the verification result of the output information of the output end of the digital intermediate frequency link includes:

and selecting parameters to be updated from a first parameter data table of the open-loop digital predistorter according to carrier configuration of the target narrowband Internet of things, current power and current temperature of the power amplifier, and replacing initial parameters of the open-loop digital predistorter with the parameters to be updated.

Optionally, obtaining output information of the output end of the digital intermediate frequency link for verification includes:

Obtaining the error vector amplitude of the output signal of the output end of the digital intermediate frequency link for verification;

and acquiring intermodulation interference level between the standard wireless signal at the output end of the digital intermediate frequency link and the carrier wave of the target narrowband internet of things, and determining whether the intermodulation interference level is lower than a set threshold value.

Optionally, the method further comprises:

determining whether the chip model of the digital-to-analog conversion module in the target remote radio unit meets the transformation requirement;

if the chip model of the digital-to-analog conversion module in the target remote radio unit does not meet the transformation requirement, determining the chip model of the digital-to-analog conversion module to be replaced according to first indexes respectively corresponding to the wireless mobile communication network system corresponding to the target remote radio unit and the chips of different digital-to-analog conversion modules, wherein the first indexes comprise signal-to-noise ratio, spurious-free dynamic range, noise spectrum density and three-boundary intermodulation distortion.

Optionally, the method further comprises:

determining whether the chip model of an analog-to-digital conversion module in the target remote radio unit meets the transformation requirement;

if the chip model of the analog-to-digital conversion module in the target remote radio unit does not meet the transformation requirement, determining the chip model of the analog-to-digital conversion module to be replaced according to second indexes respectively corresponding to the wireless mobile communication network system corresponding to the target remote radio unit and the chip models of different analog-to-digital conversion modules, wherein the second indexes comprise: signal-to-noise ratio, spurious-free dynamic range, noise spectral density, three-range intermodulation distortion, analog input bandwidth, full power bandwidth, and aperture jitter index.

Optionally, the method further comprises:

responding to gain adjustment operation, and acquiring target power gain of each power amplifier of the target remote radio unit;

under the conditions that the input end of each current power amplifier of the target remote radio unit is loaded with a signal source and the output end simulates a load, determining the power gain of each current power amplifier of the target remote radio unit;

obtaining the attenuation value of the current pi-type attenuator of the target remote radio unit;

determining a target attenuation value of the pi-type attenuator according to the power gain of each current power amplifier of the target remote radio unit and the attenuation value of the current pi-type attenuator of the target remote radio unit;

determining target resistance values corresponding to a first resistor and a second resistor in the pi-type attenuator according to the target attenuation value of the pi-type attenuator;

and respectively adjusting the resistance values of the first resistor and the second resistor in the pi-type attenuator to respectively corresponding target resistance values.

Optionally, after the resistances of the first resistor and the second resistor in the pi-type attenuator are respectively adjusted to the respective corresponding target resistances, the method further includes:

detecting the values of input impedance and output impedance of the pi-type attenuator, and adjusting the resistance values of a first resistor and a second resistor in the pi-type attenuator according to the relation among the input impedance, the output impedance and target values of the impedance;

Or, measuring the current power gain of each power amplifier of the target remote radio unit;

if the current power gain is larger than the target power gain of each power amplifier of the target remote radio unit, finely adjusting and increasing the resistance value of the first resistor and reducing the resistance value of the second resistor;

and if the current power gain is smaller than the target power gain of each power amplifier of the target remote radio unit, trimming to reduce the resistance value of the first resistor and increasing the resistance value of the second resistor.

Optionally, the method further comprises:

when each power amplifier of the target remote radio unit is a target power gain, determining a target configuration parameter of an open-loop digital predistorter of the target remote radio unit in the second parameter data table;

updating parameters of the open loop digital predistorter with the target configuration parameters;

the second parameter data table is a data table of tap parameter predictive values of the digital predistorter along with the amplitude of an input baseband signal under different carrier frequencies and temperature conditions according to the digital predistorter obtained under the simulation environment of the target remote radio unit, the standard wireless signal and the mixed carrier of the narrowband internet of things.

In a second aspect, an embodiment of the present application provides a remote radio unit, which is obtained by modifying a remote radio unit modification method for a narrowband internet of things service according to the first aspect of the embodiment, where the remote radio unit includes a digital intermediate frequency link, the digital intermediate frequency link includes a standard wireless signal downlink and a target narrowband internet of things downlink, and the target narrowband internet of things downlink includes a digital up-conversion filter, a mixer, a peak clipping device, and an open-loop digital predistorter that are sequentially connected, and the open-loop digital predistorter and an output end of a closed-loop digital predistorter of the standard wireless signal downlink are both connected to a combiner.

In a third aspect, an embodiment of the present application provides a computer readable storage medium, where a computer program is stored, where the computer program when executed by a processor implements a method for modifying a remote radio unit of a narrowband internet of things service according to the first aspect of the embodiment.

The beneficial effects are that:

the method comprises the steps that a digital intermediate frequency link standard wireless signal of a target radio remote unit added with a target downlink and a baseband signal of a target narrowband internet of things exist, the target downlink not only comprises the standard wireless signal downlink, but also comprises a target narrowband internet of things downlink for providing narrowband internet of things service, the target narrowband internet of things downlink comprises a digital up-conversion filter, a mixer, a peak clipping device and an open-loop digital predistorter which are sequentially connected, the open-loop digital predistorter and the output end of a closed-loop digital predistorter of the standard wireless signal downlink are both connected with a combiner, and the open-loop digital predistorter is provided with initial parameters.

And then obtaining the output information of the output end of the digital intermediate frequency link for verification, and performing closed-loop adjustment on the initial parameters of the open-loop digital predistorter according to the verification result of the output information of the output end of the digital intermediate frequency link until the output information of the output end of the digital intermediate frequency link meets the verification, and determining the parameters of the finally deployed open-loop digital predistorter.

According to the method, the hardware of the digital intermediate frequency link system is improved on the existing remote radio unit, the parameter setting of the open-loop digital predistorter is adjusted in a closed loop mode, and under the condition of small change range, the existing remote radio unit supports the NB-IoT carrier, so that the difficulty and the efficiency of transformation are low, the testing environment for transformation can be reused with other transformation scenes, the universality is high, the hardware and software systems of stock equipment are effectively utilized, and the life cycle of the existing remote radio unit is prolonged.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the description of the embodiments of the present application will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present application, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

Fig. 1 is a step flowchart of a method for transforming a remote radio unit of a narrowband internet of things service according to an embodiment of the present application;

FIG. 2 is a schematic diagram of a conventional digital intermediate frequency link according to an embodiment of the present application;

FIG. 3 is a schematic diagram of a modified digital intermediate frequency link system according to an embodiment of the present application;

FIG. 4 is a schematic diagram of an open loop digital predistorter instrumentation platform environment as set forth in one embodiment of the present application;

FIG. 5 is a schematic diagram of an evaluation environment of a digital-to-analog conversion module according to an embodiment of the present application;

FIG. 6 is a schematic diagram of an evaluation environment of an analog-to-digital conversion module according to an embodiment of the present application;

FIG. 7 is a schematic diagram of a remote radio unit to be retrofitted according to an embodiment of the present application;

fig. 8 is a schematic diagram of a power amplifier of a remote radio unit according to an embodiment of the present application;

fig. 9 is an interface schematic diagram of a remote radio unit supporting system configured on a network management according to an embodiment of the present application;

fig. 10 is an interface schematic diagram of configuring a power amplifier support system of a remote radio unit on a network manager according to an embodiment of the present application.

Detailed Description

The following description of the embodiments of the present application will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are some, but not all, of the embodiments of the present application. All other embodiments, which can be made by one of ordinary skill in the art based on the embodiments herein without making any inventive effort, are intended to be within the scope of the present application.

The terminology in this embodiment is explained as follows:

RRU (Radio Remote Unit, remote radio unit): the base station is an important component unit of a base station part in the mobile communication system, mainly completes the receiving and transmitting processing work of the radio frequency front end, and is one of core components of the mobile communication system; as the forefront of the wireless base station system, the RRU mainly realizes the interconversion between the digital baseband signal and the radio frequency signal, that is, transmits and receives the radio frequency radio wave signal to and from the space specific area through the antenna feed system, thereby realizing the transceiving processing between the terminals.

NB-IoT (Narrow-band Internet of things): the standard of the Internet of things is widely applied to the Internet of things service of various large operators at present, is an Internet of things communication standard which has a huge prospect and is unified worldwide, and provides a huge opportunity for the development of the Internet of things in the future; the NB-IoT may be carried in multiple mid-low frequency bands, each employing frequency division duplex mode.

LTE (Long Time Evolution, long term evolution): a wireless communication network technical standard adopts an orthogonal frequency division multiplexing technology as a basis, combines the design concepts of multi-antenna, fast packet scheduling and the like, and forms a new air interface technology facing the next generation mobile communication system.

NR (New Radio, new Radio technology): a wireless communication network technical standard, which is greatly improved to meet the requirements of 5G (5 th Generation Mobile Communication Technology, fifth generation mobile communication technology).

FPGA (Field Programmable Gate Array ): belongs to a semi-custom circuit in an application-specific integrated circuit, and can effectively solve the problem of less gate circuits of the original devices; the basic structure of the device comprises a programmable input/output unit, a configurable logic block, a digital clock management module, an embedded block RAM, wiring resources, an embedded special hard core and a bottom layer embedded functional unit; because the FPGA has the characteristics of rich wiring resources, high repeated programming and integration level and low investment, the FPGA is widely applied to the field of digital circuit design.

A transceiver board: the receiving-transmitting conversion processing function between the baseband signal and the radio frequency signal is mainly completed; the core part of the receiving and transmitting board comprises a digital signal processing chip for realizing intermediate frequency digital signal processing algorithm and peripheral related hardware control; the CPU (Central Processing Unit ) chip is used for system master control; the AD/DA (analog-to-digital conversion/digital-to-analog conversion) device is used for high-speed digital-to-analog conversion processing; the radio frequency hardware link is used for inter-frequency and filtering processing and the like.

LNA (Low Noise Amplifier ): the signal amplification device is not independent into a module, is arranged in a duplexer or a transceiver board or a power amplifier module, is used for amplifying a received signal, and is generally connected behind the duplexer.

PA (Power Amplifier): the independent module or the single board is integrated with the receiving and transmitting board, and the power amplification processing is carried out on the transmitted radio frequency signal, and the independent module or the single board is generally positioned between the receiving and transmitting board and the duplexer or at the last stage of the output of the transmitting link of the receiving and transmitting board. The PA transmitting circuit is designed with a multistage amplifier, the transmitting small signal output from the digital-to-analog conversion module is amplified to rated power, the transmitting small signal is radiated to space through an antenna after being filtered out of band by a filter, meanwhile, the output signal is sampled forwards through a coupler, the digital predistorter is used for predistortion compensation of the downlink signal, the distortion of the power amplifier is corrected, the transmitting intermodulation is improved, and the monitoring of the matching state of the PA module is realized.

Diplexer/filter: the module is used for receiving and transmitting isolation, and simultaneously carries out filtering suppression on air interface out-of-band interference, and is generally positioned between the PA module and an antenna port of the RRU equipment, namely positioned at the last stage of an RRU transmitting link and positioned at the first stage of a receiving link; because the bearing power is larger, the device is generally composed of a multi-stage resonant cavity, and the suppression of emission strays, the suppression of receiving blockage and interference signals and the RRU receiving and transmitting isolation are completed.

DUC (Digital Up Conversion, digital up-conversion): moving the digital signal to a higher frequency; taking up-down conversion of the cosine signal as an example, the cosine signal is subjected to quadrature frequency conversion and then modulated to a high frequency part.

DDC (Digital Down Conversion ): the digital signal is carried to a lower frequency, namely, the signal is subjected to down-conversion, so that the conversion from a radio frequency (intermediate frequency) signal to a baseband signal is realized, a carrier wave with strict same frequency and phase is used for obtaining a high-frequency component and a low-frequency component, and the signal can be demodulated by filtering the signal by a low-pass filter.

CFR (Crest Factor Reduction, peak clipping): the peak value of the signal is processed by adopting a proper strategy, so that the peak-to-average ratio of the signal is reduced, and the key point of peak clipping is to improve the overall efficiency of the power amplifier by improving the maximum power of the power amplifier.

DPD (Digital Pre-Distortion), digital predistortion): the object of service is a radio frequency power amplifier, i.e. the characteristics of the power amplifier are improved by the application of DPD technology, improving the quality of the transmitted signal.

CCDF (Complementary Cumulative Distribution Function ): the ratio of the peak power to the average power of the signal in a certain time interval, the probability that the forward power exceeds a given threshold, is usually taken as the peak-to-average ratio test value by using an index at 0.01% of the peak probability.

EVM (Error Vector Magnitude ): it means that at a given moment, the vector difference between the ideal error-free signal and the actual transmitted signal is often represented by the demodulated symbol I/Q constellation.

ACLR (Adjacent Channel Leakage power Ratio ): for measuring the transmission performance of the transmitter, defined as the ratio of the transmission power of the main channel to the measured power of the adjacent RF channel.

DAC (Digtal Analog Converter, digital to analog conversion module): the digital signal processing module is positioned between the digital processing module (such as a digital intermediate frequency link processing module) and the radio frequency transmitting module (such as a PA), and is mainly used for converting the digital signal processed by the digital processing module into an analog signal (possibly having a certain frequency shift function according to different radio frequency link architectures) and transmitting the analog signal to the radio frequency transmitting module.

SNR (Signal-Noise Ratio): the ratio of the root mean square amplitude of the DAC output effective signal to the root mean square amplitude sum of all spectral components except the direct current and the first 5 harmonics in dB in the nyquist domain.

THD (Total Harmonic Distortion ): the ratio of the root mean square amplitude of the DAC output signal to the root mean square sum of the first 6 harmonic components is in dBc.

SFDR (Spuriius-free Dynamic Range, spurious free dynamic range): the ratio of the root mean square amplitude of the DAC output signal to the root mean square amplitude of the highest glitch signal in the nyquist domain is in dBc.

SINAD (SIgnal to Noise And Distortion, signal to noise distortion ratio): in the nyquist band, the ratio of the root mean square value of the signal to the root mean square value of the total noise of the converter, which includes: spurious emissions, harmonic components of signals, thermal noise of devices, flicker noise, etc. due to various causes are in dBc.

NSD (Noise Spectrum Density, noise spectral density): the total noise power per bandwidth is expressed in dBFs/Hz or dBm/Hz.

IMD3 (Third Order Intermodulation Distortion, three-bound intermodulation distortion): when the DAC outputs two single tone signals, the ratio of the third order intermodulation products to the signal's own amplitude is in dBc.

ADC (Analog Digital Converter, analog to digital conversion module): the main function of the important components of the receiving channel and the feedback channel of the transceiver board is to convert the analog signals processed by the frequency conversion of the radio frequency module into digital signals (also, according to different radio frequency link frames, a certain frequency shift function can be achieved at the same time).

Input Bandwidth (analog Input Bandwidth): typically refers to the 3dB bandwidth of the analog input of the ADC device, i.e. the frequency range where the analog signal input loss does not exceed 3 dB.

FPBW (Full-power Bandwidth): defining one means that the full measurement input is lower than the low frequency of the reconstructed output fundamental frequency when the reconstructed output fundamental frequency is reduced to 3 dB; definition two refers to the maximum frequency at which the undistorted sine wave is reproduced at the op-amp output.

Aperture Jitter: also known as aperture error, refers to the variation in aperture delay time between samples; if accurate measurement is required, the data sampling system must have extremely low phase noise; as the analog input slope (dV/dt) increases, the aperture jitter also increases. Generally, when using an ADC with an input frequency in the MHz stage, the clock jitter should be in the sub-picosecond stage.

A resonant cavity: is a basic unit formed by a duplexer, and is a cavity completely sealed by metal. The duplexer/filter is composed of a band-pass filter and a low-pass filter which are composed of a plurality of resonant cavities, and the number and the size of the resonant cavities are designed through simulation programs so as to meet the parameter requirements of supporting frequency, insertion loss, intermodulation interference, out-of-band rejection and the like; the resonant cavity is typically provided with a resonant rod, the power capacity of which can be controlled by adjusting its depth.

When NB-IoT service is introduced through the transformation of the existing network remote radio unit equipment, the spectrum of NB-IoT is generally transmitted in the same remote radio unit as LTE/NR, and compared with the condition that LTE/NR is generally configured with a single carrier with 20MHz bandwidth, the bandwidth of NB-IoT is only 200kHz (including a guard band with 20kHz, the proportion is approximately equivalent to that of LTE but higher than NR); typically, the single carrier power of the NB-IoT is about 10% of the LTE/NR, so that the power spectrum density of the NB-IoT can be calculated to be 10dB higher than that of the LTE/NR, and the NB-IoT carrier is introduced into the existing remote radio unit device carrying the LTE, so that the technical problem to be solved is to introduce the NB-IoT carrier with a narrow bandwidth and a high power density into the existing LTE/NR spectrum.

The application scenario of the embodiment is to introduce NB-IoT service on the existing remote radio unit, specifically, to superimpose one or more narrowband NB-IoT carriers on the basis of the original LTE/NR wideband carrier.

Referring to fig. 1, a step flow chart of a method for transforming a remote radio unit of a narrowband internet of things service provided in an embodiment of the present application is shown, where the method includes:

s101: and loading a standard wireless signal and a baseband signal of the target narrowband Internet of things to a digital intermediate frequency link containing a target downlink in the target remote radio unit.

The standard radio signal in this embodiment refers to a narrow LTE signal or a narrow NR signal, the narrow LTE signal refers to a radio signal in FDD (Frequency Division Duplexing, frequency division duplex) duplex mode and up to 20MHz using the 3GPP (3 rd Generation Partnership Project, third generation partnership project) R8 to R14 standard, the narrow NR signal refers to a radio signal in FDD duplex mode and up to 50MHz using NB-IoT common radio frequency equipment, and the standard radio signal in this embodiment is exemplified by a narrow LTE signal.

The target downlink comprises a standard wireless signal downlink and a target narrowband internet of things downlink, the target narrowband internet of things downlink comprises a digital up-conversion filter (DUC filter), a mixer, a peak clipping device (CFR) and an open loop digital predistorter (open loop DPD) which are sequentially connected, and the open loop digital predistorter and the output end of a closed loop digital predistorter of the standard wireless signal downlink are both connected with a combiner, wherein the open loop digital predistorter is provided with initial parameters.

The existing remote radio unit hardware system consists of an intermediate frequency digital process, a digital-analog/digital conversion, a clock process, a radio frequency circuit, a power amplifier, a filtering module, a power module and a monitoring module, wherein the intermediate frequency digital process comprises an uplink and downlink interface process, a downlink DUC+CFR+DPD and an uplink DDC module, and the radio frequency circuit comprises a radio frequency receiving link, a transmitting link and a feedback link.

Referring to fig. 2, a schematic structural diagram of an existing digital intermediate frequency link provided in an embodiment of the present application is shown, in logic, a module architecture of a remote radio unit may further include a digital intermediate frequency link, a DAC/ADC and an analog subsystem, where the digital intermediate frequency link is actually located between the baseband DAC/ADC, and includes a plurality of digital devices such as filters and DPD, and is further divided into two parts according to a signal flow direction: the circuit and the processing part between the ADC data input and output to the baseband processing are called a digital receiving link, and mainly comprise a frequency shift, a DDC filter bank, an FIR filter and the like; the circuit and the processing part between the baseband data input and output to the DAC are called a digital transmitting link, and mainly comprise an FIR filter, a DUC filter bank, a mixing combiner, CFR, DPD and the like; the electronic components inside the digital intermediate frequency link are actually integrated on the FPGA, so that the configuration of these components can be modified with integrated circuit development software more conveniently, and a circuit from ADC to DPD is further provided for feeding back PA to DPD, which is part of the DPD adaptation mechanism.

Referring to fig. 3, a schematic diagram of a modified digital intermediate frequency link system provided in an embodiment of the present application is shown, in this embodiment, a remote radio unit of a model is first selected as a target remote radio unit, and then the digital intermediate frequency link system in the target remote radio unit is modified, which specifically includes:

a1: in the FPGA of the target remote radio unit, 1 DUC filter is added to each of two DUC filter groups, and up-conversion of the corresponding NB-IoT carrier wave is completed.

A2: for each DUC filter added in A1, 1 mixer is added at the back, and the frequency of the mixing corresponds to the carrier frequency corresponding to NB-IoT, i.e. as a parameter input.

A3: for each mixer added in A2, 1 cfr+dpd element is added later, and since the NB-IoT carrier carried by the DPD here is very narrow, the condition of using open loop DPD (the ratio of carrier frequency to carrier bandwidth is greater than 100) is reached, so the DPD for the NB-IoT carrier added in this embodiment adopts an open loop DPD scheme.

After the digital intermediate frequency link system in the target remote radio unit is modified, the initial parameters of the open loop DPD are also determined.

In one possible embodiment, the first parameter data table of the open loop DPD may be obtained through simulation training.

Specifically, according to the model of the remote radio unit and the multiple carrier types of the target narrowband internet of things, performing simulation training on the working states of the open-loop digital predistorter under different parameters to obtain a first parameter data table of the open-loop digital predistorter, wherein the first parameter data table comprises carrier configurations of different target narrowband internet of things and parameter values of the open-loop digital predistorter corresponding to different powers and environment temperatures of a power amplifier of the digital intermediate frequency link.

Referring to fig. 4, a schematic diagram of an open-loop digital predistorter instrument platform environment provided in an embodiment of the present application is shown, firstly, a simulation environment of an open-loop DPD is constructed, specifically, 1 PC (Personal Computer ) for simulation, 1 real digital signal source, DAC in use model, 1 spectrometer/data acquisition card and 1 PA in use model and its attached feedback BPF (Berkeley Packet Filter ) and ADC are configured; the PC, the digital signal source and the frequency spectrograph are all provided with network cards, and in one LAN (Local Area Network ), data are connected through Ethernet; the synchronous signal and the trigger signal are transmitted between the signal source and the spectrometer/data acquisition card through a signal line; the output end of the signal source is connected with the DAC, the analog signal output by the DAC is connected with the PA input, the BPF back of the PA feedback channel is connected with the ADC, and the output digital signal of the ADC is connected with the spectrometer/data acquisition card; the temperature information of the PA is fed back to a spectrometer/a data acquisition instrument by a data line; the environmental temperature around the PA can be regulated within the allowable range of the equipment, and the test evaluation environment is used for simulating the operation of real equipment, so that the real equipment is modified in actual operation, and a spectrometer/data acquisition instrument and a signal source are connected to corresponding ports of a main board.

Then, training parameters aiming at the model of the RRU to be targeted and the target NB-IoT carrier wave, recording the obtained parameters, and specifically configuring a simulated signal source, a DPD program and a DPD parameter training program on a PC; configuring an NB-IoT intermediate frequency digital signal to be simulated on a PC, wherein the digital signal is the output of a mixer, and executing a simulation process; collecting feedback of the power amplifier by a frequency spectrograph or a data acquisition card, wherein the feedback comprises a digital signal and the actual temperature of the power amplifier; running a DPD parameter training program on a PC, and recording a training result, wherein the core is a filter input coefficient which needs to be loaded by the DPD under the current carrier configuration, power and PA actual temperature conditions; changing the current carrier configuration, power and environment temperature, repeating the above operations to obtain a more detailed data table, and generating a first parameter data table.

The initial parameters of the open loop DPD are obtained from a first parameter data table, specifically, in the first parameter data table, according to the carrier configuration actually deployed, the corresponding initial parameters are selected and written into the EEPROM (Electrically Erasable Programmable read only memory, charged erasable programmable read-only memory) of the corresponding channel PA, and then the target RRU system is started to execute the update mechanism of the open loop DPD parameters, so that the initial parameters can be configured for the open loop DPD.

S102: and obtaining the output information of the output end of the digital intermediate frequency link for verification.

The combiner is configured behind the DPD, namely, two input ends of each combiner are respectively connected with the DPD of the LTE and the DPD of the NB-IoT, the output end is connected with a 204B output interface of the FPGA, and the output end is connected with digital signal analysis software by loading baseband signals of the LTE and the target NB-IoT at the input end of each downlink digital intermediate frequency link (namely, before the FIR filter).

In a possible implementation manner, the digital signal analysis software obtains the error vector amplitude of the output signal of the output end of the digital intermediate frequency link, such as checking a constellation diagram EVM; and acquiring intermodulation interference level between the standard wireless signal of the output end of the digital intermediate frequency link and the carrier wave of the target narrowband internet of things, and determining whether the intermodulation interference level is lower than a set threshold value.

S103: and performing closed-loop adjustment on initial parameters of the open-loop digital predistorter according to the verification result of the output information of the output end of the digital intermediate frequency link until the output information of the output end of the digital intermediate frequency link meets the verification, and determining parameters of the finally deployed open-loop digital predistorter.

And according to a verification result of output information of an output end of the digital intermediate frequency link, performing closed loop adjustment on initial parameters of the open loop digital predistorter, and if a constellation diagram EVM of an output signal does not meet a requirement or intermodulation interference level between LTE and NB-IoT carriers is not lower than a set threshold value in any process of verifying the output information, selecting parameters to be updated from a first parameter data table of the open loop DPD according to carrier configuration of the target NB-IoT, and replacing the initial parameters of the open loop DPD with the parameters to be updated until the output information of the output end of the digital intermediate frequency link meets the verification, determining parameters of the finally deployed open loop digital predistorter, wherein a target RRU after primary transformation is completed can be obtained.

In a possible implementation manner, in order to improve the performance of the RRU in providing the narrowband internet of things service, the DAC chip in the target RRU may be further modified.

Specifically, determining whether the chip model of the digital-to-analog conversion module in the target remote radio unit meets the transformation requirement;

if the chip model of the digital-to-analog conversion module in the target remote radio unit does not meet the transformation requirement, determining the chip model of the digital-to-analog conversion module to be replaced according to first indexes respectively corresponding to the wireless mobile communication network system corresponding to the target remote radio unit and the chips of different digital-to-analog conversion modules, wherein the first indexes comprise a signal-to-noise ratio (SNR), a spurious-free dynamic range (SFDR), a Noise Spectrum Density (NSD) and three-boundary intermodulation distortion (IMD).

Specifically, according to the wireless mobile communication network system supported by needs, such as 2 LTE carriers and 2 NB-IoT carriers, the product description of different DAC chips is queried, then the requirement of the DAC module on the first index is analyzed by adopting simulation software, and the unified model selection is performed by combining factors such as the price of the DAC device, the design difficulty, the maturity of the device, the reliability of the device, the producibility of the device, the type of the data interface and the like.

In practical implementation, a database of different DAC chips can be constructed, wherein the database comprises information such as the price of a device, the design difficulty, the maturity of the device, the reliability of the device, the producibility of the device, the type of a data interface and the like of the DAC, then screening conditions are preset, different information is set for the screening weight, the scores of the different DAC chips are comprehensively determined, the DAC chips with the scores ranging from high to low in front n are simulated, and finally the chip model of the digital-analog conversion module to be replaced is determined.

Referring to fig. 5, an evaluation environment schematic diagram of a digital-to-analog conversion module provided in the present application is shown, where a DAC device evaluation environment includes a DAC evaluation board (i.e., an evaluated DAC chip), a dc regulated power supply, a signal source, a spectrometer, a high-speed data generation board, and a PC, and the DAC device evaluation environment is used to evaluate a first index including a signal-to-noise ratio (SNR), a spurious-free dynamic range (SFDR), a Noise Spectral Density (NSD), and a three-boundary intermodulation distortion (IMD), where in other embodiments, the first index may further include other parameter indexes such as flatness, inter-channel isolation, ACPR (Adjacent Channel Leakage Ratio ), and the like, to determine a chip model of the digital-to-analog conversion module to be replaced.

In one possible implementation, the ADC chip in the target RRU may also be retrofitted.

Specifically, determining whether the chip model of an analog-to-digital conversion module in the target remote radio unit meets the transformation requirement; if the chip model of the analog-to-digital conversion module in the target remote radio unit does not meet the transformation requirement, determining the chip model of the analog-to-digital conversion module to be replaced according to second indexes respectively corresponding to the wireless mobile communication network system corresponding to the target remote radio unit and the chip models of different analog-to-digital conversion modules, wherein the second indexes comprise: signal-to-noise ratio (SNR), spurious-free dynamic range (SFDR), noise Spectral Density (NSD), three-bound intermodulation distortion (IMD 3), analog Input Bandwidth (Input Bandwidth), full Power Bandwidth (FPBW), and aperture jitter index.

Specifically, according to a wireless mobile communication network system supported by needs, such as 2 LTE carriers+2 NB-IoT carriers, product specifications of different ADC chips are obtained, simulation software is adopted to analyze requirements of the ADC module on second indexes, the second indexes include indexes such as SNR, SFDR, NSD, IMD, input Bandwidth, FPBW, aperture jitter, and the like, and unified type selection is performed in combination with factors such as price, design difficulty, maturity of the ADC device, reliability of the device, producibility of the device, data interface type, and the like.

In practical implementation, a database of different ADC chips can be constructed, wherein the database comprises information such as device price, design difficulty, maturity of devices, reliability of devices, producibility of devices, data interface type and the like of the ADC, then screening conditions are preset, different information is set for screening weights, scores of the different ADC are comprehensively determined, simulation is carried out on the ADC with the score ranging from high to low in the front n, and finally the chip model of the analog-digital conversion module to be replaced is determined.

Referring to fig. 6, an evaluation environment schematic diagram of an analog-to-digital conversion module provided by the application is shown, an ADC device evaluation environment includes an ADC evaluation board (i.e. an evaluated ADC chip), a dc voltage-stabilizing power supply, a clock signal source, a band-pass filter, a high-precision signal source, a high-speed data acquisition board and a PC, a digital analysis method is adopted to analyze a digital signal output by the high-speed data acquisition board by using the ADC device evaluation environment, and an evaluation second index includes indexes such as SNR, SFDR, NSD, IMD, input Bandwidth, FPBW, aperture jitter, and the like, and further includes key parameters such as THD (total harmonic distortion), SINAD (signal to noise distortion ratio), and the like, so as to determine a chip model of the analog-to-digital conversion module to be replaced.

In a possible implementation manner, the power gain of the power amplifier, i.e. the PA, may also be adjusted to expand the gain of each transmit channel PA in the target RRU; illustratively, the gains of the two PAs are expanded in the existing RRU device, and the power amplifier pi-type attenuator is adjusted so that the maximum output power of the PA is expanded from 46dBm to 47.78dBm, which is the power required to support NB-IoT functionality.

In one possible implementation, the process of adjusting the power gain of the PA may include:

specifically, in response to a gain adjustment operation, obtaining a target power gain of each PA of the target RRU; and then, under the conditions that a signal source is loaded at the input end of each current PA of the target RRU and a load is simulated at the output end, determining the power gain of each current PA of the target RRU.

Then obtaining the attenuation value of the current pi-type attenuator of the target RRU; in the actual implementation process, the first resistance value and the second resistance value of the current pi-type attenuator can be obtained through table lookup calculation, a relation table of the first resistance, the second resistance and the attenuation value Lar is queried, and the attenuation value of the current pi-type attenuator is matched and calculated.

And then determining a target attenuation value of the pi-type attenuator according to the current power gain of each PA of the target RRU and the attenuation value of the current pi-type attenuator of the target RRU.

Then, according to the target attenuation value of the pi-type attenuator and the target power gain of each PA, further inquiring a relation table of the first resistor, the second resistor and the attenuation value Lar, and determining target resistance values corresponding to the first resistor and the second resistor in the pi-type attenuator; and respectively adjusting the resistance values of the first resistor and the second resistor in the pi-type attenuator to respectively corresponding target resistance values.

In the practical implementation process, the resistors with adjustable resistance ranges can be further set for the first resistor and the second resistor, so that the resistance values of the first resistor and the second resistor in the pi-type attenuator can be automatically adjusted to respectively corresponding target resistance values, or a target resistance value prompt of the first resistor and the second resistor can be output to prompt a worker to replace the resistors with the corresponding resistance values.

In a possible implementation manner, after the resistances of the first resistor and the second resistor in the pi-type attenuator are respectively adjusted to the corresponding target resistances, the method may further coarsely adjust the resistances of the pi-type attenuator, that is, calculate the target values of the first resistor and the second resistor in the pi-type attenuator by using a linear interpolation method according to the target resistances of the first resistor and the second resistor, and adjust the resistances of the first resistor and the second resistor in the pi-type attenuator according to the target values.

The resistance value of the pi-type attenuator can be continuously and finely adjusted to meet the numerical requirements of gain and impedance, specifically, the values of the input impedance and the output impedance of the pi-type attenuator are detected, and the resistance values of a first resistor and a second resistor in the pi-type attenuator are adjusted according to the relation among the input impedance, the output impedance and the target values of the impedance; or, measuring the current power gain of each PA of the target remote radio unit; if the current power gain is larger than the target power gain of each PA of the target remote radio unit, finely adjusting and increasing the resistance value of the first resistor and reducing the resistance value of the second resistor; if the current power gain is less than the target power gain of each PA of the target remote radio unit, then the fine tuning decreases the resistance of the first resistor and increases the resistance of the second resistor by continuously coarse tuning and fine tuning until the values of gain and impedance are very close to the desired values.

In a possible implementation manner, the DAC of the DAC chip type to be replaced, the ADC of the ADC chip type to be replaced, and the second calibration of the open-loop DPD parameter when each PA of the target remote radio unit is the target power gain may be further configured in the target remote radio unit.

Specifically, in the open loop DPD meter platform environment, the hardware and software to be tested are configured, including: placing a practically adopted forward circuit DAC and a practically adopted feedback circuit ADC into an open-loop DPD instrument platform; and placing each transmitting channel PA module in the expanded target RRU into a platform.

Then configuring LTE plus target NB-IoT intermediate frequency digital signals to be simulated on a PC, wherein the digital signals are the output of a mixer, and starting a simulation system; collecting feedback of the power amplifier through a frequency spectrograph or a data acquisition card, wherein the feedback comprises a digital signal and an actual temperature; running a DPD parameter training program on a PC, and recording a training result, wherein the core is a filter input coefficient which needs to be loaded by the DPD under the current carrier configuration, power and PA actual temperature conditions; changing the current carrier configuration, power and environment temperature, repeating the above operations to obtain a more detailed data table, and generating a second parameter data table.

Configuring an LTE/NR+NB-IoT intermediate frequency digital signal to be emulated on a PC of an open loop DPD meter platform, the digital signal should be the output of a mixer; the training object of the step is the model of the remote radio unit to be modified and the mixed carrier of LTE/NR and NB-IoT, the output parameters are DPD predicted value data tables, namely the data tables of DPD tap parameter predicted values along with the amplitude of baseband input signals under different carrier frequencies and temperature conditions, and the training algorithm model adopts the same parameter training algorithm model in the closed loop DPD feedback adopted by the remote radio unit to be modified in the LTE/NR signal digital link.

Then selecting target configuration parameters of open-loop DPD in a second parameter data table, and writing the selected corresponding target configuration parameters into the EEPROM of the corresponding channel PA; starting a remote radio unit system to execute an updating mechanism of parameters of DPD, including the steps that the PA determines target configuration parameters of the open-loop DPD in a table look-up and interpolation mode according to the power detection value and the temperature which are obtained by current measurement, and returns the target configuration parameters to a CPU on a transceiver board, and the CPU updates the open-loop DPD corresponding to the channel according to the target configuration parameters.

And finally, expanding the power capacity of the Rong Shuanggong device/filter in the existing target remote radio unit, adjusting the resonance rod of the duplex filter, and properly increasing the power capacity of the duplex filter.

In a possible implementation manner, the software system of the target remote radio unit can be correspondingly modified, specifically, configuration parameters of the software subsystem of the remote radio unit are modified, and the driver is reloaded; and configuring relevant parameters of the remote radio unit on a wireless network manager to complete network access of the remote radio unit, and finally completing introduction of NB-IoT service. The method specifically comprises the following steps:

b1: and configuring parameters of a remote radio unit software subsystem.

B11: and adding a driving program for NB-IoT communication in a configuration file of the driving program of the remote radio unit, and loading the driving program into a software subsystem of the remote radio unit through software upgrading.

B12: and adding a protocol stack of NB-IoT communication in a configuration file of the remote radio unit driver, and loading the protocol stack into a remote radio unit software subsystem through software upgrading.

B13: on the basis of a protocol stack configured by B12, parameters of NB-IoT communication parameters including parameters such as a frequency band (e.g. B3) of an NB-IoT cell, a maximum carrier number (e.g. 1) of the NB-IoT, a single NB-IoT carrier bandwidth (e.g. 200 kHz), a maximum power (47.78 dBm in the present case) of the RRU and the like are configured, a target RRU driver is restarted, and configuration updating is completed.

B2: the network access of the target RRU and the introduction of NB-IoT service after transformation specifically comprise:

b21: the original RRU is replaced by the modified RRU, and the optical port and the power wiring are completely consistent with the original RRU.

B22: and importing the hardware data configuration of the modified RRU on the wireless network management, and covering the original configuration.

B23: and configuring a system support list of the modified RRU on the wireless network manager, and enabling the NB-IoT option.

B24: and configuring a standard support list of each power amplifier of the modified RRU on the wireless network manager, and enabling the NB-IoT.

B25: and adding cell parameters, carrier parameters and templated baseline parameters of the NB-IoT on the wireless network manager, reactivating the cell, and finally completing the network access of the RRU and the introduction of the NB-IoT service.

The existing remote radio unit has complete functional modules, and specifically, comprises all modules in a complete digital intermediate frequency link system; further, the invention comprises the following technical points:

(1) The reconstruction focuses on a digital intermediate frequency link system in an RRU system, wherein the system is generally integrated in a transceiver board (namely an RRU main board) and comprises the steps of training and adjusting the combination and connection relation of internal modules integrated in an FPGA and parameters of open loop DPD;

(2) Further matching with testing and adjusting the model of DAC and ADC, supporting the new added NB-IoT carrier wave;

(3) Further matching with the power parameter of the PA, meeting the increase of the output power after the NB-IoT is overlapped, and comprising the second iterative adjustment of the open loop DPD parameter;

(4) Further matching with a tuning rod of the duplexer/filter to increase the power capacity of the duplexer/filter;

(5) After each hardware transformation is executed, the effect achieved is that the analog radio frequency signal finally output by the downlink and the digital signal output by the uplink optical port are both satisfied, and the nonlinear characteristics of the signals after the superposition of NB-IoT carrier frequency and LTE/NR carrier frequency are effectively controlled, including harmonic wave, forward intermodulation, receiving frequency band transmitting intermodulation and reverse intermodulation;

(6) Further adjusting, loading a related communication protocol stack by a driver of the target RRU software subsystem, and configuring NB-IoT communication parameters and a software program adapted by the device to adapt to the change of the parameters after the hardware transformation;

(7) Further configuring parameters of the target RRU and the power amplifier in the target RRU on the wireless network manager, completing the network access of the target RRU, and verifying and confirming the reconstruction effect.

The method completes the transformation of the RRU on the premise of not changing the whole software and hardware architecture of the existing RRU and not changing main hardware components so as to achieve the technical problem of introducing NB-IoT: the method specifically comprises the following beneficial effects:

firstly, the modification method mainly only involves the modification of configuration parameters in a software system except that the ADC/DAC small chip with low cost needs to be replaced, so that the hardware cost is low, and the overall cost is easy to control;

the tools used for transformation are universal integrated circuit configuration tools and universal hardware simulation tools, a common RRU maintenance workshop is provided with configuration, verification can be carried out through a test environment in the maintenance workshop after transformation, the transformation difficulty is low, the efficiency is high, the test environment used for transformation can be reused with other transformation scenes, and the universality is strong;

Thirdly, the hardware and software systems of the stock equipment are effectively utilized, the life cycle of the RRU is prolonged, and the system is low-carbon and environment-friendly;

and fourthly, the transformation method has strong universality and can be applied to all RRUs compatible with FDD systems, including various types of 4G and 5G.

In a possible implementation, the basic situation of the RRU for transformation is 1.8G RRU, the model is R8862A S1800 (A4A), the target transformation model is R8862A S1800 (B6A), and the comparison between the original model and the target model is as follows:

table 1 parameter comparison before and after RRU retrofit

The antenna receiving and transmitting mode of the RRU is 2T4R, specifically 1 and 4 ports are receiving and transmitting integrated ports, so that a duplexer is required to be configured; 2. the 3-port is a single-receive port, so that there is no need to configure a diplexer.

The process of reforming the digital intermediate frequency link system of the RRU is as follows:

referring to fig. 7, a schematic diagram of a remote radio unit to be modified is shown, where the RRU has two transmit links and four receive links, and since the bandwidth of the LTE carrier reaches 20MHz, a closed loop DPD must be used, that is, an output signal needs to be acquired from the PA, and the DPD is fed back through devices such as a BPF and an ADC.

Firstly, adding 1 DUC filter in two DUC filter groups respectively in an FPGA to finish up-conversion of corresponding NB-IoT carriers; adding 1 mixer behind each DUC filter, wherein the frequency of the mixer corresponds to the carrier frequency corresponding to NB-IoT, namely, the carrier frequency is used as a parameter input; each mixer, with the addition of 1 cfr+dpd element, the increased DPD for the NB-IoT carrier employs an open loop DPD scheme because the NB-IoT carrier carried by the DPD here is very narrow, reaching conditions where open loop DPD is used (carrier frequency to carrier bandwidth ratio greater than 100).

Setting up an open-loop DPD instrument platform environment, and configuring 1 PC for simulation, 1 real digital signal source, 1 DAC of the in-use model, 1 spectrometer/data acquisition card, 1 power amplifier PA of the in-use model and feedback BPF and ADC attached to the power amplifier PA; the PC, the digital signal source and the frequency spectrograph are all provided with network cards, and in one LAN, data are connected through Ethernet; the synchronous signal and the trigger signal are transmitted between the signal source and the spectrometer/data acquisition card through a signal line; the output end of the signal source is connected with the DAC, the analog signal output by the DAC is connected with the PA input, the BPF back of the PA feedback channel is connected with the ADC, and the output digital signal of the ADC is connected with the spectrometer/data acquisition card; the temperature information of the PA is fed back to a spectrometer/a data acquisition instrument by a data line; the environmental temperature around the PA can be regulated within the allowable range of the equipment, and the test evaluation environment is used for simulating the operation of real equipment, so that the real equipment is modified in actual operation, and a spectrometer/data acquisition instrument and a signal source are connected to corresponding ports of a main board.

Training parameters aiming at RRU models and NB-IoT carriers to be modified, and recording the obtained parameters, wherein the specific flow is as follows: configuring a simulated signal source, a DPD program and a DPD parameter training program on a PC; configuring an NB-IoT intermediate frequency digital signal to be simulated on a PC, wherein the digital signal is the output of a mixer, and starting a simulation system; collecting feedback of the power amplifier through a frequency spectrograph or a data acquisition card, wherein the feedback comprises a digital signal and an actual temperature; running a DPD parameter training program on a PC, and recording a training result, wherein the core is a filter input coefficient which needs to be loaded by the DPD under the current carrier configuration, power and PA actual temperature conditions; changing the current carrier configuration, power and ambient temperature, repeating the above operations, and obtaining a more detailed data table as the first parameter data table.

And in the first parameter data table, according to the carrier configuration of actual deployment, selecting corresponding initial parameters to write into the EEPROM of the corresponding channel PA, and then starting the target RRU system to execute an updating mechanism of the open loop DPD parameters, so that the initial parameters can be configured for the open loop DPD.

Further, the combiners are configured behind the DPD, namely, two input ends of each combiner are respectively connected with the DPD of the LTE and the DPD of the NB-IoT, and the output ends of the combiners are connected with the 204B output interface of the FPGA.

Further, loading LTE plus NB-IoT baseband signals at the input end of each downlink digital intermediate frequency link (i.e. before the FIR filter), terminating digital signal analysis software at the output end, confirming that the constellation diagram EVM of the output signals meets the requirement, and that intermodulation interference level between LTE and NB-IoT carriers is lower than a set threshold value; if not, readjusting parameters of the open loop DPD.

As shown in fig. 4, the structure of the RRU to be modified after modification is shown, and the structure of the digital intermediate frequency link system of the RRU to be modified has been changed through the above process.

And then other hardware devices of the RRU can be modified, and three devices of the DAC/DAC, the PA and the duplexer are modified according to the connection sequence of the hardware structures.

The DAC device in the RRU is modified, specifically, the current DAC chip type of the RRU is checked, and if the current DAC chip type of the RRU can meet the modification requirement, the modification is not performed; otherwise, the DAC chip is selected, and in this embodiment, since the existing DAC chip already meets the requirements, the DAC chip is not replaced.

The ADC chip in the RRU is modified, specifically, the model of the ADC chip currently used by the RRU is checked, and if the current model can meet the modification requirement, the modification is not performed; otherwise, the ADC chip is selected, and in this embodiment, the NB-IoT carrier is added, so that the FPBW condition is not met, and the ADC121S051CIMF/NOPB model is replaced by the ADC121S051CIMFX/NOPB model.

The gains of the two PAs can be expanded in the RRU equipment to be modified, and the pi-type attenuator of the power amplifier is adjusted, so that the maximum output power of the PAs is expanded from the original 46dBm to 47.78dBm, and the power required by supporting the NB-IoT function is realized. The PA of the target RRU adopts a Doherty architecture.

Referring to fig. 8, a schematic structural diagram of a power amplifier of a remote radio unit provided in an embodiment of the present application is shown, where the power amplifier includes a pi-type attenuator, and the pi-type attenuator is composed of 3 adjustable resistors, and is originally used for temperature compensation, and by adjusting impedance values of 3 resistors in the pi-type attenuator, an effect of reducing an attenuation value of the attenuator by 1.78dB is finally achieved.

Specifically, the method for measuring the power gain of the PA before the transformation specifically comprises loading a signal source at the input end of the PA, connecting a load to the output end, and respectively measuring the power P of the input end _in And output power P _out,0 The calculated power gain of the PA is:

then calculating to obtain resistance value of the pi-type attenuator after transformation, specifically measuring the values of R1 and R2 in the current pi-type attenuator, inquiring a relation table of the R1, R2 and the attenuation value Lar, matching and calculating the attenuation value L of the pi-type attenuator before transformation ₀ According to the PA power gain G before modification ₀ Further calculating the attenuation value L of the pi-type attenuator after transformation ₁ ＝L ₀ -1.78, PA power gain G after modification ₁ ＝G ₀ +1.78; then, the relation table of R1, R2 and the attenuation value Lar is queried, and according to L ₁ The values match and the values of R1 and R2 in the modified pi-type attenuator are calculated.

A table of the relationship between R1, R2 and the attenuation value Lar is shown in Table 2.

Table 2 R1, R2 and the relation table of attenuation Lar (input impedance and output impedance are 50Ω)

Then, the resistance values of R1 and R2 in the pi-type attenuator can be roughly adjusted by a linear interpolation method, wherein the linear interpolation algorithm is as follows: let the target attenuation value be L ₀ The attenuation values of the upper and lower rows in the corresponding table are L respectively ₁ And L ₂ Satisfy L ₁ ≤L ₀ <L ₂ Let L ₁ ≤L ₀ <L ₂ The two resistance values corresponding to the two rows are R respectively ₁₁ 、R ₂₁ And R is ₁₂ 、R ₂₂ L is then ₀ Corresponding two resistance values R ₁₀ 、R ₂₀ The method comprises the following steps of:

then fine-tuning the pi-type attenuator resistance to meet the numerical requirements of gain and impedance, specifically comprising (a) matching impedance step: measuring the value Z of the input impedance and the output impedance of a pi-type attenuator ₁ And Z ₂ Assuming that the target value of the impedance is Z, if Z ₁ And Z ₂ All are larger than Z, the resistance value of R1 is reduced, and then Z is reduced ₁ And Z ₂ The resistance value of R2 on the larger side of the resistor; if Z ₁ And Z ₂ All are smaller than Z, the resistance value of R1 is increased, and then Z is increased ₁ And Z ₂ The resistance value of R2 on the smaller side of the capacitor; other cases are where Z is at Z ₁ And Z ₂ Between them, Z is lowered ₁ And Z ₂ The resistance value of R2 on the larger side of the alloy is increased and Z is increased ₁ And Z ₂ A resistance value of R2 on the smaller side of (b) a matching gain step: measuring current PA power gain G, if G>G ₁ The resistance value of R1 is finely adjusted to be increased, and the resistance values of two R2 are reduced; otherwise, the fine tuning is performed to decrease the resistance value of R1 and increase the resistance value of R2, and the steps (a) and (b) are alternately and iteratively performed until the values of the gain and the impedance are close to those to be achievedThe obtained values are up to.

Then the open loop DPD parameters can be calibrated by using the constructed open loop DPD instrument platform environment, and specifically, a forward circuit DAC and a feedback circuit ADC which are actually adopted are put into the platform; and placing the expanded PA module into a platform, training the parameters, and recording the obtained parameters.

The specific flow is as follows: configuring an LTE+NB-IoT intermediate frequency digital signal to be simulated on a PC, wherein the digital signal is the output of a mixer, and starting a simulation system; collecting feedback of the power amplifier through a frequency spectrograph or a data acquisition card, wherein the feedback comprises a digital signal and an actual temperature; running a DPD parameter training program on a PC, and recording a training result, wherein the core is a filter input coefficient which needs to be loaded by the DPD under the current carrier configuration, power and PA actual temperature conditions; changing the current carrier configuration, power and ambient temperature, repeating the above operations, and obtaining a more detailed data table as a second parameter data table.

In the existing RRU equipment, the power capacity of a duplexer/filter is expanded, the resonance rod of the duplex filter is adjusted, the resonance rod is rotated out, and the power capacity of the duplexer/filter is properly increased.

And finally, modifying the matched software system, wherein the method specifically comprises the steps of configuring parameters of an RRU software subsystem, replacing the original RRU with the modified RRU, and completing the network access of the RRU and the introduction of NB-IoT service.

Fig. 9 is a schematic diagram of an interface for configuring a remote radio unit support system on a network manager, and configuring a system support list of a modified RRU on a wireless network manager, so as to enable NB-IoT options.

Referring to fig. 10, an interface schematic diagram of configuring a power amplifier support system of a remote radio unit on a network manager is shown, and a system support list of each power amplifier of a modified RRU is configured on a wireless network manager to enable NB-IoT.

And finally, adding cell parameters, carrier parameters and templated baseline parameters of the NB-IoT on the wireless network manager, reactivating the cell, and finally completing the network access of the RRU and the introduction of the NB-IoT service.

The embodiment of the application also provides a computer readable storage medium, wherein the computer readable storage medium stores a computer program, and the computer program realizes the remote radio unit reconstruction method of the narrowband internet of things service according to the embodiment when being executed by a processor.

In this specification, each embodiment is described in a progressive manner, and each embodiment is mainly described by differences from other embodiments, and identical and similar parts between the embodiments are all enough to be referred to each other.

It will be apparent to those skilled in the art that embodiments of the present application may be provided as a method, apparatus, or computer program product. Accordingly, the present embodiments may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, embodiments of the present application may take the form of a computer program product on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) having computer-usable program code embodied therein.

Embodiments of the present application are described with reference to flowchart illustrations and/or block diagrams of methods, terminal devices (systems), and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing terminal device to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing terminal device, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

While preferred embodiments of the present embodiments have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. It is therefore intended that the following claims be interpreted as including the preferred embodiments and all such alterations and modifications as fall within the scope of the embodiments of the present application.

Finally, it is further noted that relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or terminal that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or terminal. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article or terminal device comprising the element.

The principles and embodiments of the present application are described herein with specific examples, the above examples being provided only to assist in understanding the methods of the present application and their core ideas; meanwhile, as those skilled in the art will have modifications in the specific embodiments and application scope in accordance with the ideas of the present application, the present description should not be construed as limiting the present application in view of the above.

Claims

1. The method for modifying the remote radio unit of the narrowband internet of things service is characterized by comprising the following steps:

2. The method according to claim 1, wherein the method further comprises:

3. The method of claim 2, wherein performing closed-loop adjustment on the initial parameters of the open-loop digital predistorter according to the verification result of the output information of the output end of the digital intermediate frequency link comprises:

4. The method of claim 1, wherein obtaining the output information of the digital intermediate frequency link output for verification comprises:

5. The method according to claim 1, wherein the method further comprises:

6. The method of claim 5, wherein the method further comprises:

7. The method of claim 6, wherein the method further comprises:

8. The method of claim 7, wherein after adjusting the resistances of the first resistor and the second resistor in the pi-type attenuator to the respective corresponding target resistances, the method further comprises:

9. The method of claim 8, wherein the method further comprises:

10. The remote radio unit is characterized in that the remote radio unit is obtained by being modified based on the method for modifying the remote radio unit of the narrowband internet of things service according to any one of claims 1-9, the remote radio unit comprises a digital intermediate frequency link, the digital intermediate frequency link comprises a standard wireless signal downlink and a target narrowband internet of things downlink, the target narrowband internet of things downlink comprises a digital up-conversion filter, a mixer, a peak clipping device and an open-loop digital predistorter which are sequentially connected, and the open-loop digital predistorter is connected with an output end of a closed-loop digital predistorter of the standard wireless signal downlink.

11. A computer readable storage medium, wherein a computer program is stored on the computer readable storage medium, and when the computer program is executed by a processor, the method for modifying a remote radio unit of a narrowband internet of things service according to any one of claims 1 to 9 is implemented.