WO2017147759A1

WO2017147759A1 - Method and device for cancelling passive intermodulation interference

Info

Publication number: WO2017147759A1
Application number: PCT/CN2016/074871
Authority: WO
Inventors: 王磊; 李晶; 陈莹莹; 谢尔盖莫宁
Original assignee: 华为技术有限公司
Priority date: 2016-02-29
Filing date: 2016-02-29
Publication date: 2017-09-08
Also published as: CN109075808A; CN109075808B

Abstract

A method and device for cancelling passive intermodulation (PIM) interference are provided to resolve the problem of reception performance of a communication apparatus being affected by passive intermodulation interference. The device cancelling passive intermodulation interference comprises: an acquisition module used to acquire from a plurality of transmitting channels a transmitting signal; a frequency shift module used to perform a frequency shift on the plurality of transmitting signals acquired by the acquisition module; a nonlinear transform module used to perform a nonlinear transformation on the plurality of frequency-shifted transmitting signals to generate a cancellation signal; and an inverse superposition module used to superimpose an additive inverse of the cancellation signal on a receiving signal to cancel the passive intermodulation interference in the signal. When the communication apparatus having a plurality of transmitting channels receives a receiving signal, the communication apparatus can cancel out the passive intermodulation interference in the signal, preventing reception performance of the communication apparatus from being affected.

Description

Passive intermodulation interference cancellation method and device

Technical field

The present application relates to the field of wireless communication technologies, and in particular, to a passive intermodulation (PIM) interference cancellation method and apparatus.

Background technique

Passive intermodulation interference is an important factor limiting the capacity of wireless communication systems. Passive intermodulation interference is caused by the nonlinear characteristics of various devices in the transmit channel (such as duplexers, antennas, feeders, RF line connectors, etc.). Due to the high power characteristics of the wireless communication system, the passive components in the antenna feeder system will generate strong nonlinear effects, thereby generating a new set of frequency signals, ie, passive intermodulation signals, if the passive intermodulation signals fall In the receiving frequency band, and the power exceeds the minimum amplitude of the useful signal in the system, it will affect the receiving performance of the communication device. At this time, the passive intermodulation signal is called "passive intermodulation interference".

As the bandwidth of communication devices continues to increase, the impact of passive intermodulation interference on signal reception is increasing.

In summary, in a wireless communication system, there is a problem that passive intermodulation interference affects the reception performance of the communication device.

Summary of the invention

In view of this, the present application provides a passive intermodulation interference cancellation method and apparatus for solving the problem that the passive intermodulation interference existing in the wireless communication system affects the reception performance of the communication device.

In a first aspect, the present application provides a passive intermodulation interference cancellation device, the device comprising:

An acquisition module, configured to respectively acquire digital intermediate frequency transmission signals from multiple transmission channels;

The frequency shifting module is configured to: according to the radio frequency band corresponding to each of the plurality of transmitting channels, the frequency interval of the radio frequency band corresponding to the different transmitting channels, and the radio frequency band corresponding to one of the plurality of receiving channels, the acquiring module Acquire multiple digital intermediate frequency transmission signals into The line frequency is moved so that the radio frequency signal corresponding to the cancellation signal generated by the non-linear transformation of the plurality of digital intermediate frequency transmission signals after the frequency shift falls into the radio frequency receiving frequency band of the receiving channel;

The nonlinear transformation module is configured to perform nonlinear transformation on the plurality of digital intermediate frequency transmission signals after the frequency shifting module performs frequency shifting, and generate a cancellation signal for canceling passive intermodulation interference in the digital intermediate frequency reception signal on the receiving channel. ;

The inverse superposition module is configured to inversely superimpose the generated cancellation signal on the digital intermediate frequency reception signal to cancel the passive intermodulation interference in the digital intermediate frequency reception signal.

Passive intermodulation interference is caused by nonlinear transformation between multiple transmitted RF signals caused by nonlinear devices, and RF signals transmitted between different transmission channels may also be generated. Source intermodulation interference.

With the above scheme, the acquisition module obtains digital intermediate frequency transmission signals from multiple transmission channels, taking into account the passive intermodulation interference that may occur between different transmission channels, and the frequency shifting module performs frequency shifting on the digital intermediate frequency transmission signal. The linear transformation module performs nonlinear transformation to generate a cancellation signal for canceling passive intermodulation interference in the digital intermediate frequency received signal on the receiving channel, thereby enabling passive intermodulation interference in an application scenario in which multiple transmission channels exist The cancellation solves the problem that the passive intermodulation interference affects the receiving performance of the communication device in the wireless communication system.

In a possible implementation manner, the nonlinear transformation module is further configured to: perform nonlinear transformation on the multi-channel digital intermediate frequency transmission signal after the frequency shifting module performs frequency shifting, and generate a digital intermediate frequency reception for canceling the receiving channel. Before the canceling signal of the passive intermodulation interference in the signal, determine the multivariate nonlinear substrate used in the nonlinear transformation, the number of elements of the multivariate nonlinear substrate is equal to the number of channels of the plurality of transmitting channels; determining each of the multivariate nonlinear substrates The coefficient of the nonlinear substrate;

The nonlinear transform module performs nonlinear transformation on the multi-channel digital intermediate frequency transmission signal after the frequency shifting module performs frequency shifting, and generates a cancellation signal for canceling the passive intermodulation interference in the digital intermediate frequency received signal on the receiving channel. Specifically, the plurality of digital intermediate frequency transmission signals after frequency shifting by the frequency shifting module are calculated according to the multivariate nonlinear base and the coefficients of each nonlinear base, and are obtained for canceling the digital intermediate frequency receiving signal on the receiving channel. The cancellation signal of the passive intermodulation interference.

With the above scheme, the nonlinear transform module determines the form of the nonlinear transform by determining the nonlinear base used by the nonlinear transform and the coefficients of the nonlinear base, and the canceled signal obtained by the above nonlinear transform can be used to cancel the passive mutual Adjust the interference signal.

In a possible implementation manner, when determining the coefficient of each nonlinear base in a set of nonlinear substrates, the nonlinear transform module is specifically configured to: preset each of the multivariate nonlinear substrates when the cancel signal is generated for the first time The coefficient of the nonlinear substrate; when the cancellation signal is subsequently generated, the coefficients of each nonlinear substrate in the multivariate nonlinear substrate are calculated according to the error signal;

The error signal is the difference between the last received digital intermediate frequency received signal and the last generated cancellation signal.

According to the above scheme, since the nonlinear transform module presets the coefficient of each nonlinear base in the multivariate nonlinear base when the cancel signal is generated for the first time, the coefficient of the nonlinear base is solved according to the error signal when the cancel signal is subsequently generated, and thus the nonlinear transform The coefficients of the nonlinear base calculated by the module are more accurate, so that the generated cancellation signal is more accurate and can more accurately cancel the passive intermodulation interference.

In a possible implementation, each of the plurality of digital intermediate frequency transmission signals includes: a digital intermediate frequency transmission signal at a current time on a transmission channel where the digital intermediate frequency transmission signal is located; and/or the digital intermediate frequency transmission a digital intermediate frequency transmission signal at a plurality of times before the current time on the transmitting channel where the signal is located;

The current time is the time at which the generated cancellation signal is inversely superimposed on the digital intermediate frequency reception signal.

With the above scheme, the digital intermediate frequency transmission signal is not only related to the digital intermediate frequency transmission signal at the current moment, but also related to the transmission signal of the previous moments at the current moment, that is, the memory characteristic is added to the expression of the digital intermediate frequency transmission signal, so that the digital intermediate frequency is added. The transmitted signal is more accurately expressed, which makes the cancellation signal expression more accurate and more accurately cancels the passive intermodulation interference.

In a possible implementation manner, multiple transmit channels respectively correspond to different radio frequency bands; or multiple transmit channels are connected to the same antenna, and different transmit channels have different antenna polarization directions; or multiple transmit channels are connected differently. An antenna, wherein one transmitting channel corresponds to one antenna; or a plurality of transmitting channels are combined by a radio frequency matrix network to connect multiple antennas.

In a second aspect, the present application provides a passive intermodulation interference cancellation method, which may be a pass The signaling device, such as a base station or a wireless terminal, performs the method, and the method includes:

Obtaining a digital intermediate frequency transmission signal from each of the plurality of transmission channels;

For one of the multiple receiving channels, perform the following operations: according to the radio frequency band corresponding to each of the multiple transmitting channels, the frequency interval of the radio frequency band corresponding to the different transmitting channels, and the radio frequency band corresponding to the receiving channel, Performing frequency shifting on the acquired plurality of digital intermediate frequency transmission signals, so that the radio frequency signals corresponding to the cancellation signals generated by the non-linear transformation of the plurality of digital intermediate frequency transmission signals after the frequency shift fall into the radio frequency receiving frequency band of the receiving channel And performing nonlinear transformation on the plurality of digital intermediate frequency transmission signals after the frequency shifting, generating a cancellation signal for canceling the passive intermodulation interference in the digital intermediate frequency reception signal on the receiving channel; and superimposing the generated cancellation signal in the reverse direction The digital intermediate frequency receives the signal to cancel the passive intermodulation interference in the digital intermediate frequency received signal.

Using the above scheme, taking into account the passive intermodulation interference that may occur between different transmission channels, the digital intermediate frequency transmission signals are respectively obtained from the plurality of transmission channels, and the digital intermediate frequency transmission signals are frequency-shifted and then subjected to nonlinear transformation processing to Generating a cancellation signal for canceling passive intermodulation interference in the digital intermediate frequency received signal on the receiving channel, thereby enabling cancellation of passive intermodulation interference in an application scenario where multiple transmission channels exist, and solving the wireless communication system, Passive intermodulation interference affects the reception performance of communication equipment.

In a possible implementation manner, the multi-channel digital intermediate frequency transmission signal after the frequency shift is nonlinearly transformed to generate a cancellation signal for canceling the passive intermodulation interference in the digital intermediate frequency received signal on the receiving channel. And including: determining a multivariate nonlinear substrate used in performing nonlinear transformation, the number of elements of the multivariate nonlinear substrate being equal to the number of channels of the plurality of emission channels; determining coefficients of each nonlinear substrate in the multivariate nonlinear substrate;

Performing nonlinear transformation on the multi-channel digital intermediate frequency transmission signal after frequency shifting, generating a cancellation signal for canceling passive intermodulation interference in the digital intermediate frequency reception signal on the receiving channel, including: The plurality of digital intermediate frequency transmission signals after frequency shifting are operated according to the multivariate nonlinear base and the coefficients of each nonlinear base to obtain a cancellation signal for canceling the passive intermodulation interference in the digital intermediate frequency received signal on the receiving channel. .

With the above scheme, the nonlinear transform is determined by determining the nonlinear base used by the nonlinear transform and the nonlinear base, and the canceled signal obtained by the nonlinear transform can be used to cancel the passive intermodulation interference signal.

In a possible implementation, determining coefficients of each of the nonlinear substrates in the set of nonlinear substrates includes: determining a coefficient of each of the nonlinear bases in the multivariate nonlinear substrate when the cancellation signal is first generated;

When the cancellation signal is subsequently generated, the coefficient of each nonlinear base in the multivariate nonlinear substrate is calculated according to the error signal; wherein the error signal is the difference between the last received digital intermediate frequency received signal and the last generated cancellation signal.

According to the above scheme, since the coefficient of each nonlinear base in the preset multivariate nonlinear base is generated when the cancel signal is generated for the first time, the coefficient of the nonlinear base is solved according to the error signal when the cancel signal is generated, and the coefficient of the nonlinear base is calculated. More accurate, the resulting cancellation signal is more accurate and more accurately offsets passive intermodulation interference.

In a possible implementation, each of the plurality of digital intermediate frequency transmission signals includes: a digital intermediate frequency transmission signal at a current time on a transmission channel where the digital intermediate frequency transmission signal is located; and/or the digital intermediate frequency transmission The digital intermediate frequency transmission signal at the previous moments of the current time on the transmitting channel where the signal is located; the current time is the time at which the generated cancellation signal is inversely superimposed on the digital intermediate frequency receiving signal.

In a possible implementation manner, multiple transmit channels respectively correspond to different radio frequency bands; or multiple transmit channels are connected to the same antenna, and antennas of different transmit channels have different polarization directions; Or multiple transmitting channels are connected to different antennas, wherein one transmitting channel corresponds to one antenna; or multiple transmitting channels are combined by a radio frequency matrix network to connect multiple antennas.

In a third aspect, the present application provides a passive intermodulation interference cancellation device, where the passive intermodulation interference cancellation device is connected to multiple transmission channels and one receiving channel of a communication device, including:

The frequency shifting circuit is configured to: according to the radio frequency band corresponding to each of the plurality of transmitting channels, the frequency interval of the radio frequency band corresponding to the different transmitting channels, and the radio frequency band corresponding to one of the plurality of receiving channels, to the plurality of The digital intermediate frequency transmission signals on each of the transmission channels are respectively frequency-shifted, so that the radio frequency signals corresponding to the cancellation signals generated by the non-linear transformation of the plurality of digital intermediate frequency transmission signals after the frequency shift fall into the receiving channel In the radio frequency receiving frequency band;

a canceller, configured to perform nonlinear transformation on the plurality of digital intermediate frequency transmission signals after frequency shifting by the frequency shifting circuit, to generate a cancellation signal for canceling passive intermodulation interference in the digital intermediate frequency received signal on the receiving channel;

The adder is configured to inversely superimpose the cancellation signal generated by the canceller on the digital intermediate frequency receiving signal received on the receiving channel to cancel the passive intermodulation interference in the digital intermediate frequency receiving signal, and superimpose the canceling signal in the reverse direction The digital IF receives the signal output.

With the above scheme, considering the passive intermodulation interference that may occur between different transmission channels, the frequency shifting circuit performs frequency shifting on the digital intermediate frequency transmission signal acquired from the plurality of transmission channels, and then performs nonlinear transformation by the canceller to Generating a cancellation signal for canceling passive intermodulation interference in the digital intermediate frequency received signal on the receiving channel, thereby enabling cancellation of passive intermodulation interference in an application scenario where multiple transmission channels exist, and solving the wireless communication system, Passive intermodulation interference affects the reception performance of communication equipment.

In a possible implementation manner, the canceller is further configured to: perform nonlinear transformation on the multi-channel digital intermediate frequency transmission signal after the frequency shifting circuit performs frequency shifting, and generate and cancel the receiving channel. Before the digital intermediate frequency receives the cancellation signal of the passive intermodulation interference in the signal, the multivariate nonlinear substrate used in the nonlinear transformation is determined, and the number of elements of the multivariate nonlinear substrate is equal to the number of channels of the plurality of transmission channels; The coefficient of each nonlinear substrate in the linear substrate;

The canceller performs nonlinear transformation on the multi-channel digital intermediate frequency transmission signal after the frequency shifting circuit performs frequency shifting, and generates a cancellation signal for canceling the passive intermodulation interference in the digital intermediate frequency received signal on the receiving channel, The plurality of digital intermediate frequency transmission signals after frequency shifting by the frequency shifting circuit are calculated according to the multivariate nonlinear base and the coefficients of each nonlinear base, and are obtained for canceling the absence of the digital intermediate frequency receiving signal on the receiving channel. The offset signal of the source intermodulation interference.

With the above scheme, the canceller determines the form of the nonlinear transform by determining the nonlinear base used by the nonlinear transform and the coefficient of the nonlinear base, and the canceled signal obtained by the nonlinear transform can be used to cancel the passive intermodulation interference signal. .

In a possible implementation manner, when determining the coefficient of each nonlinear substrate in a set of nonlinear substrates, the canceller is specifically configured to: preset each nonlinearity in the multivariate nonlinear substrate when the cancellation signal is generated for the first time The coefficient of the substrate; when the cancellation signal is subsequently generated, the coefficients of each nonlinear substrate in the multivariate nonlinear substrate are calculated according to the error signal;

According to the above scheme, since the canceller presets the coefficient of each nonlinear base in the multivariate nonlinear base when the cancel signal is generated for the first time, the coefficient of the nonlinear base is solved according to the error signal when the cancel signal is subsequently generated, and thus the canceller solves the calculated The coefficients of the nonlinear substrate are more accurate, so that the generated cancellation signal is more accurate and can more accurately cancel the passive intermodulation interference.

DRAWINGS

1 is a schematic diagram of an intermodulation interference cancellation scheme when a communication device provided by the present application has a transmission channel;

2 is a schematic diagram of a scenario of multi-band radio frequency combining provided by the present application;

3 is a schematic diagram of a scheme for passive intermodulation interference in scenario 2 of canceling multiple antennas provided by the present application;

4 is a schematic diagram of a scheme for passive intermodulation interference in the scenario of the offset radio frequency matrix network provided by the present application;

FIG. 5 is a schematic diagram of a passive intermodulation interference cancellation scheme provided by the present application; FIG.

6 is a flowchart of a passive intermodulation interference cancellation method provided by the present application;

FIG. 7 is a schematic diagram of a passive intermodulation interference cancellation method according to a scenario provided by the present application; FIG.

FIG. 8 is a flowchart of a passive intermodulation interference cancellation method according to a scenario provided by the present application;

FIG. 9 is a schematic diagram of a scenario of an adaptive solution process according to the present application; FIG.

10 is a schematic diagram of a passive intermodulation interference cancellation method in scenario 2 according to the present application;

11 is a flowchart of a passive intermodulation interference cancellation method in scenario 2 according to the present application;

12 is a schematic diagram of an adaptive solution process in scenario 2 provided by the present application;

FIG. 13 is a schematic diagram of a passive intermodulation cancellation device provided by the present application.

detailed description

For a better understanding of the above objects, aspects and advantages of the present application, a detailed description is provided below. The detailed description sets forth various embodiments of the devices and/or methods in the <RTIgt; In these block diagrams, flowcharts, and/or examples, one or more functions and/or operations are included. Those skilled in the art will appreciate that the various functions and/or operations within the block diagrams, flowcharts or examples can be implemented individually or collectively by various hardware, software, firmware, or by any of hardware, software and firmware. Combined implementation.

In the present application, a scheme for passive intermodulation interference cancellation is proposed for a scenario in which multiple transmit channels, passive intermodulation interference, and signals transmitted on multiple transmit channels exist.

In the solution, a communication device, such as a base station, respectively obtains a digital intermediate frequency transmission signal from a plurality of transmission channels; performs frequency shifting on the acquired plurality of digital intermediate frequency transmission signals; and acquires one of the plurality of reception channels for the acquired channel A plurality of digital intermediate frequency transmission signals are nonlinearly transformed to generate a cancellation signal for canceling passive intermodulation interference in the digital intermediate frequency reception signal on the receiving channel; and the generated cancellation signal is inversely superimposed on the digital intermediate frequency reception signal, To cancel the passive intermodulation interference in the digital intermediate frequency received signal.

Passive intermodulation interference is caused by nonlinear transformation between multiple transmitted RF signals caused by nonlinear devices, and RF signals transmitted between different transmission channels may also be generated. Source intermodulation interference. In this application, considering the passive intermodulation interference that may occur between different transmission channels, the data intermediate frequency transmission signals are respectively obtained from multiple transmission channels to generate a cancellation signal for canceling the passive intermodulation interference. Effectively cancels passive intermodulation interference between multiple transmit channels.

In the following, the scenarios in which the present application can be applied are introduced. In these scenarios, the communication device has multiple transmit channels, and the passive intermodulation interference is related to the signals transmitted on the multiple transmit channels.

It should be noted that the following description should not be taken as limiting the scope of protection claimed herein.

Scene 1: Multiple transmit channels correspond to different transmit bands

In engineering implementation, this scenario can also be called "multi-band RF combining." In this scenario, the radio frequency signals transmitted by the communication device are located in different frequency bands. At this time, the source signal that generates the passive intermodulation interference is not the signal on one frequency band, but the signal obtained after the multiple transmission signals of the multiple frequency bands are combined.

Scene 2: Multiple transmit channels correspond to different transmit antennas

In wireless communication systems, multi-antenna technology is often used to increase spectrum utilization and resource transmission efficiency.

In the multi-antenna technology, the communication device is configured with multiple transmitting antennas and multiple receiving antennas, and the signals transmitted by different antennas are combined in the radiation field space near the antenna, and the combined signals will be passive at the common intermodulation interference source. Intermodulation interference.

Here, the common passive intermodulation interference source may be a metal body in a radiation field near the antenna, such as: an inner metal frame of the antenna, a metal rod on the front side of the antenna, a multi-polarized antenna enclosure, and a metal of a multi-polarized antenna radiation field. Hold the pole and so on. After the multi-channel RF signal transmitted by the communication device is combined in the radiation field space near the antenna, the passive intermodulation interference is excited at the common passive intermodulation interference source.

Scene 3: Multiple transmit channels correspond to different polarization directions of the transmit antennas

In scenario 3, the communication device has multiple transmission channels, and the plurality of transmission channels are connected to the vibrators of different polarization directions of the same antenna, that is, the signals transmitted by different transmission channels are different in polarization.

For example, the communication device has two transmitting channels, which are respectively connected to the +45 degree polarization direction and the -45 degree polarization direction of the same antenna.

Scene 4, multiple transmission channels respectively correspond to multiple input ports of the radio frequency matrix network

In scenario four, the transmit signals on multiple transmit channels are mixed through a radio frequency matrix network (such as a radio frequency bridge, a Butler matrix) and fed to the antennas. These signals excite passive intermodulation interference sources in the antenna (eg, inside the antenna) The burr solder joints, stress-failed screws, etc.), thereby forming passive intermodulation interference. The passive intermodulation interference is again superimposed on the received signal in the RF matrix network before being inverted into the receive channel.

The above describes the applicable scenarios of the present application. It should be noted that the above scenario is only an example, as long as the communication device has multiple transmission channels, passive intermodulation interference and signals transmitted on multiple transmission channels. Regarding the number, the scheme provided in this application can be used to eliminate passive intermodulation interference.

In addition, when the actual project is implemented, there may be a mixture of the above several scenarios, for example, the communication device has multiple transmit antennas, and each of the transmit antennas transmits signals of multiple radio frequency bands; for example, the communication device has multiple transmissions. Antennas, each transmitting antenna distinguishes different polarization directions to transmit signals on different transmission channels, and the like.

When the communication device has only one transmission channel, the interference cancellation scheme shown in FIG. 1 can be used to cancel the passive intermodulation interference.

In the scheme shown in Figure 1, the passive intermodulation interference is cancelled on the digital intermediate frequency side by the canceller. In Figure 1, PIM RXC is a canceller for canceling passive intermodulation interference, x is a digital intermediate frequency transmission signal transmitted on the transmission channel, rx is a digital intermediate frequency reception signal received on the receiving channel, and y is generated by RXC. A cancellation signal that cancels the passive intermodulation interference, and Rx is a digital intermediate frequency reception signal after removing the passive intermodulation interference.

In FIG. 1, according to the transmission direction of the signal, the transmission signal is transmitted from the left to the right transmission direction, and the channel through which the corresponding transmission signal passes is the transmission channel; the transmission signal is transmitted from the right to the left in the transmission direction. The channel through which the corresponding received signal passes is the receiving channel.

For the transmitted signal, the baseband signal is upsampled by a Sample Rate Converter (SRC), and the upsampled baseband transmit signal is digitally upconverted (Digital Up Converter, DUC) to obtain a digital intermediate frequency transmit signal, digital intermediate frequency transmission. The signal is subjected to digital-to-analog conversion (DAC) to generate an analog IF transmission signal. The analog transmission signal is mixed (ie, the analog IF transmission signal is mixed with the RF local oscillation signal TX_LO) to obtain an analog RF transmission signal. The RF transmit signal is amplified by a Power Amplifier (PA), and then input to a transmit duplexer (TX Duplexer, TX_DUP) and input to an antenna feed system (not shown). The digital intermediate frequency transmission signal x output by the DUC is frequency-shifted (x*exp(jwt)) and input to the canceller (PIM RXC), and the PIM RXC generates a cancellation signal, which is inversely superimposed on the digital intermediate frequency receiving signal. To offset the interference of passive intermodulation.

For the received signal, the analog RF received signal from the antenna feeder system (not shown) passes through the receiving duplexer (RX Duplexer, RX_DUP) and is then a Low Noise Amplifier (Low Noise Amplifier, LNA) performs signal amplification processing. Optionally, the amplified analog RF received signal is filtered by a Surface Acoustic Wave (SAW) filter, and the filtered analog RF received signal is subjected to receive mixing (ie, simulation) The RF signal is mixed with the RF receiving signal RX_Lo, and then the analog IF receiving signal is obtained, and then subjected to the intermediate frequency filtering of the Intermediate Frequency (IF) filter, and then passed through an analog to digital converter (ADC). )) Converted to digital IF receive signal.

After the canceling signal outputted by the canceller is superimposed on the digital intermediate frequency receiving signal, the passive intermodulation interference is cancelled, and the obtained digital intermediate frequency signal is processed by a digital down converter (DDC) to become a digital baseband receiving signal. Then, it is sent to the SRC for downsampling processing, and the intermediate frequency high rate sample rate is converted to the baseband low rate sample rate.

Wherein, x may be a single carrier signal or a multi-carrier signal. Taking x as the input of the canceller, the canceling signal y is obtained after passing through the canceller, and the canceling signal y is subtracted from the received digital intermediate frequency signal rx to obtain the digital intermediate frequency receiving signal Rx after removing the passive intermodulation interference.

The scheme of interference cancellation shown in FIG. 1 is not applicable to the foregoing scenario 1 to scenario 4, and is illustrated as follows.

1. The interference cancellation scheme shown in Figure 1 does not apply to scenario one.

Figure 2 shows a scenario of multi-band RF combining. FIG. 2 only shows the process of performing passive intermodulation interference cancellation on the first receiving channel, and the processes of passive intermodulation interference cancellation by other receiving channels are similar, which are not shown in the figure.

Since the passive intermodulation interference is formed after multiple transmission signals are frequency-shifted and combined, the canceller architecture shown in FIG. 1 is used to implement the cancellation of the passive intermodulation interference, and the digital intermediate frequency is required to transmit the signal. Mixing is performed, and the mixed signal is input to the canceller to generate a cancellation signal. However, this implementation has major limitations, mainly reflected in the following two aspects:

1. The parameters required to mix the transmitted signals at the digital intermediate frequency are difficult to obtain.

As shown in FIG. 2, when the digital intermediate frequency is used to mix the transmitted signals, the signals of the respective radio frequency bands need to be frequency-shifted and accurately combined with the combining parameters, such as the frequency point and the initial phase. Among them, the initial phase of the digital intermediate frequency should be consistent with the combined phase of the analog RF. It’s hard to get a simulation at digital IF. The phase information of the modulator of the radio frequency, which results in the parameters required to mix the transmitted signals at the digital intermediate frequency is difficult to obtain.

2. Mixing the transmitted signal at the digital intermediate frequency requires a higher sampling rate.

In the implementation manner shown in FIG. 2, since the transmission signals are mixed in the digital intermediate frequency, and the intermodulation signals are generated by mixing the radio frequency transmission signals on the transmission channels, the intermediate frequency signals are mixed in the digital intermediate frequency and then passively interacted with each other. The offset of the modulation interference needs to reflect the relative frequency difference (frequency interval) of the RF signal at the digital intermediate frequency. Sometimes, the RF frequency difference is much higher than the IF sampling rate (or sample rate). Therefore, the mixed RF signal is expressed in the digital intermediate frequency, which requires a high sampling rate (or sample rate), which is costly.

For the sake of simplicity, it is assumed that there are two transmit channels: transmit channel 1 and transmit channel 2, and the two transmit channels correspond to two radio frequency bands, respectively. The IF frequency corresponding to the transmission channel 1 is 0 MHz, the bandwidth is 10 M, the IF frequency corresponding to the transmission channel 2 is 10 MHz, and the bandwidth is 20 M; the RF frequency corresponding to the transmission channel 1 is 1.8 GHz, and the RF frequency corresponding to the transmission channel 2 is 2.1 GHz. At this time, it is necessary to express the mixed signal at the digital intermediate frequency (2120MHz-1795MHz)*3 sampling rate, so that different digital transmission channels can be distinguished in the digital intermediate frequency, and such a high sampling rate is realized at the digital intermediate frequency. Large, difficult to achieve.

Following the interference cancellation scheme shown in FIG. 1, it is difficult to implement the digital intermediate frequency to mix the transmission signals of the multiple transmission channels and then generate the cancellation signal by using the mixed signals.

Second, the interference cancellation scheme shown in Figure 1 does not apply to scenario two.

If the interference cancellation scheme shown in FIG. 1 is used, a scheme for canceling the passive intermodulation interference in the scenario 2 of the multi-antenna can be as shown in FIG. 3. For the sake of simple description, two schemes are shown in FIG. The transmitting antenna and the two receiving antennas are exemplified. In practice, the number of transmitting antennas and receiving antennas is not limited to two.

As shown in FIG. 3, the multiplexed signals are first mixed to generate a mixed signal, and the mixed signals are input to a canceller to generate a cancellation signal. The expression of the mixed signal can be:

c=a*x ₀ *exp(jw ₀ t)+b*x ₁ *exp(jw ₁ t)

Where x ₀ is the digital intermediate frequency transmission signal of the transmission channel 1, x ₁ is the digital intermediate frequency transmission signal of the transmission channel 2, w ₀ is the frequency difference between the digital intermediate frequency transmission signal and the radio frequency transmission signal of the transmission channel ₁ , and w ₁ is the transmission channel The frequency difference between the digital intermediate frequency transmitted signal and the radio frequency signal, a, b represents the transmission complex parameters (including amplitude and phase) of the transmission path from the two channels to the common passive intermodulation interference source, such as a, b parameters In the digital intermediate frequency, it is usually not accurately known. Therefore, in the scenario of multiple antennas, it is difficult to accurately cancel the passive intermodulation interference by using the scheme shown in FIG.

Third, the interference cancellation scheme shown in Figure 1 does not apply to scenario four.

If the interference cancellation scheme shown in FIG. 1 is used, a scheme for canceling the passive intermodulation interference in the scenario of the radio frequency matrix network can be as shown in FIG. 4. FIG. 4 exemplifies only two transmitting antennas and two receiving antennas. In practice, the number of transmitting antennas and receiving antennas is not limited to two. The implementation shown in FIG. 4 is that the multi-channel transmission signals are mixed and input to the canceller to generate a cancellation signal, wherein the signal input to the canceller can be expressed as c=a*x ₀ *exp(jw ₀ t) +b*x ₁ *exp(jw ₁ t), where a and b represent the duplex parameters of the duplexer to the RF matrix network, and then to the passive intermodulation interference source on the antenna (including phase and amplitude), a, The parameters such as b are not accurately known, so the input signal of passive intermodulation interference in the matrix feed network scenario is difficult to accurately represent.

FIG. 5 is a schematic diagram of a passive intermodulation interference cancellation scheme provided by the present application. As shown in FIG. 5, in the present application, a plurality of transmission channels (such as the transmission channel 0, the transmission channel 1, the transmission channel N, and the like in FIG. 5, wherein N is a positive integer) correspond to the digital intermediate frequency transmission signal (FIG. 5). The frequency shift (x ₀ , x ₁ ... x _{N ,} etc.) is carried out (the shift factor is ω ₀ , ω ₁ ... ω _{N in} Fig. 5) and then sent to a canceller for canceling the passive intermodulation interference, the offset The device uses a multivariate nonlinear model. The canceling signal y for canceling the passive intermodulation interference in the digital intermediate frequency receiving signal rx is obtained by nonlinearly transforming the digital intermediate frequency transmitting signal in the canceller, and the actually received digital intermediate frequency receiving signal rx is subtracted from the canceling signal y. The digital intermediate frequency received signal Rx after removing the passive intermodulation interference can be obtained.

A passive intermodulation interference cancellation method provided by the present application may be as shown in FIG. 6. The specific steps may include:

S601: a communication device, for example, the base station obtains digital intermediate frequency transmission from multiple transmission channels respectively. signal;

The communication system applicable to the communication device in the present application at the time of signal transmission and reception includes but is not limited to: Global System of Mobile communication (GSM), Code Division Multiple Access (CDMA) IS- 95, Code Division Multiple Access (CDMA) 2000, Time Division-Synchronous Code Division Multiple Access (TD-SCDMA), Wideband Code Division Multiple Access (WCDMA) ), Time Division Duplexing-Long Term Evolution (TDD LTE), Frequency Division Duplexing-Long Term Evolution (FDD LTE), Long Term Evolution-Enhancement (Long Term Evolution- Advanced, LTE-advanced), Personal Handy-phone System (PHS), Wireless Fidelity (WiFi), and Worldwide Interoperability for Microwave Access (WiMAX) as defined by the 802.11 series of protocols. And various wireless communication systems that will evolve in the future.

In the present application, the communication device may be a base station or a wireless terminal.

The wireless terminal can be a device that provides voice and/or data connectivity to the user, a handheld device with wireless connectivity, or other processing device that is connected to the wireless modem. The wireless terminal can communicate with one or more core networks via a radio access network (eg, RAN, Radio Access Network), which can be a mobile terminal, such as a mobile phone (or "cellular" phone) and with a mobile terminal The computers, for example, can be portable, pocket-sized, handheld, computer-integrated or in-vehicle mobile devices that exchange language and/or data with the wireless access network. For example, personal communication service (PCS, Personal Communication Service) telephone, cordless telephone, Session Initiation Protocol (SIP) telephone, Wireless Local Loop (WLL) station, Personal Digital Assistant (PDA, Personal Digital Assistant), etc. . A wireless terminal may also be called a Subscriber Unit, a Subscriber Station, a Mobile Station, a Mobile, a Remote Station, an Access Point, and a Remote Terminal. (Remote Terminal), Access Terminal, User Terminal, User Agent, User Device, or User Equipment (User) Equipment).

For the GSM system, the base station may include a Base Transceiver Station (BTS) and/or a Base Station Controller (BSC); for the TD-SCDMA system, the WCDMA system, the base station may include a Node B (NodeB, NB) And/or a Radio Network Controller (RNC); for an LTE system, the base station may be an eNB.

Optionally, multiple transmit channels respectively correspond to different radio frequency bands; or multiple transmit channels are connected to the same antenna entity, and different transmit channels have different antenna polarization directions; or multiple transmit channels are connected to different antenna entities, where One transmitting channel corresponds to one antenna; or multiple transmitting channels are combined by a radio frequency matrix network to connect multiple antennas. The multiple antennas described herein include multiple ports of one antenna entity and each port corresponds to a different polarization direction, and may also include multiple physical antennas.

S602: Perform frequency shifting on the acquired plurality of digital intermediate frequency transmission signals according to a radio frequency band corresponding to each of the plurality of transmission channels, a frequency interval of the radio frequency band corresponding to the different transmission channels, and a radio frequency band corresponding to the receiving channel. The radio frequency signal corresponding to the cancellation signal generated by the non-linear transformation of the plurality of digital intermediate frequency transmission signals after the frequency shifting falls into the radio frequency receiving frequency band of the receiving channel;

Wherein, the cancellation signal may be a digital intermediate frequency cancellation signal;

Optionally, the radio frequency signal corresponding to the cancellation signal falls into the radio frequency receiving frequency band of the receiving channel, and the frequency of the radio frequency signal corresponding to the cancellation signal is the same as the center frequency of the radio frequency receiving frequency band of the receiving channel, or may be a cancellation signal. The spectrum of the corresponding radio frequency signal partially or completely overlaps the spectrum of the radio frequency receiving frequency band of the receiving channel.

Alternatively, the frequency shifting factor used in performing frequency shifting may be determined according to the expression of different nonlinear substrates.

S603: Perform non-linear transformation on the plurality of digital intermediate frequency transmission signals after the frequency shift, to generate a cancellation signal for canceling passive intermodulation interference in the digital intermediate frequency reception signal on the receiving channel;

The communication device performs nonlinear transformation on the plurality of digital intermediate frequency transmission signals after the frequency shift for one of the plurality of receiving channels, and generates a digital intermediate frequency connection for canceling the receiving channel. a cancellation signal for passive intermodulation interference in the received signal;

Optionally, each of the plurality of digital intermediate frequency transmission signals includes: a digital intermediate frequency transmission signal at a current time on a transmission channel where the digital intermediate frequency transmission signal is located; and/or a transmission channel where the digital intermediate frequency transmission signal is located a digital intermediate frequency transmission signal at a plurality of times before the current time;

The current time is a time at which the generated cancellation signal is inversely superimposed on the digital intermediate frequency reception signal.

Optionally, performing non-linear transformation on the multi-channel digital intermediate frequency transmission signal after the frequency shifting to generate a cancellation signal for canceling the passive intermodulation interference in the digital intermediate frequency reception signal on the receiving channel may include the following steps:

1. Determine a multivariate nonlinear substrate used in the nonlinear transformation, the number of elements of the multivariate nonlinear substrate being equal to the number of channels of the plurality of transmitting channels;

The multivariate nonlinear substrate can be expressed in various ways, for example, a power function basis, an orthogonal polynomial base, a segmented spline base, a trigonometric base, and the like. The expression of the substrate has no direct effect on the offset of the passive intermodulation interference.

2. determining coefficients of each of the nonlinear substrates in the multivariate nonlinear substrate;

Optionally, determining a coefficient of each of the nonlinear substrates in the set of nonlinear substrates may include: presetting the coefficients of each of the nonlinear bases in the multivariate nonlinear substrate when the cancellation signal is first generated; and subsequently generating the cancellation signal And calculating, according to the error signal, a coefficient of each nonlinear base in the multivariate nonlinear base; wherein the error signal is a difference between the last received digital intermediate frequency received signal and the last generated canceled signal.

Optionally, the coefficients in the multivariate nonlinear base can be adaptively solved by Least Mean Square (LMS), Least Square (LS), and Recursive Least Square (RLS). Guidelines or methods for real-time updates.

Optionally, the error signal and the nonlinear substrate may be narrowband filtered separately when performing the adaptive solution.

3. Perform nonlinear transformation on multiple digital intermediate frequency transmission signals after frequency shifting, according to multiple non- The linear substrate and the coefficients of each nonlinear substrate are operated to obtain a cancellation signal.

Optionally, the passive intermodulation interference is generated when the plurality of digital intermediate frequency transmission signals are passively intermodulated. Therefore, multiple digital intermediate frequency transmission signals are used to express passive intermodulation interference, such as in a frequency band. Modulating components, third-order intermodulation components between frequency bands, and fifth-order intermodulation components between frequency bands, etc. In engineering practice, generally only intermodulation components of the fifth order or less are used, because higher order intermodulation components are smaller, and signals are received. The interference is not big. Specifically, which of the plurality of digital intermediate frequency transmission signals is selected to express the passive intermodulation interference can be determined according to the combination of the transmission frequency point and the reception frequency point, and the decision process can be implemented by software.

Optionally, a plurality of digital intermediate frequency transmission signals may be mixed during nonlinear transformation, and the mixed digital intermediate frequency transmission signal is regarded as a digital intermediate frequency transmission signal, and frequency mixing is performed on the mixed digital intermediate frequency transmission signal. The linear substrate selection and coefficient solution, the signal obtained by the operation of the nonlinear substrate and the base coefficient is used as a component of the cancellation signal.

S604: The cancellation signal generated in step S603 is inversely superimposed on the digital intermediate frequency receiving signal to cancel the passive intermodulation interference in the digital intermediate frequency receiving signal.

A passive intermodulation interference cancellation method according to the foregoing scenario provided by the present application is described below with reference to FIG. 7. FIG. 7 is an example of canceling passive intermodulation interference in a dual-band hybrid networking scenario. In practice, multiple frequency bands are not limited to two frequency bands.

The passive intermodulation interference in the dual-band hybrid networking scenario is related to the digital intermediate frequency transmission signals corresponding to the two frequency bands. The basic principle of canceling the passive intermodulation interference generated by the dual-band digital intermediate frequency transmission signal is: on the digital intermediate frequency side, using two transmit signals in different frequency bands, generated by a canceller (for example, PIM RXC in Fig. 7) A component of equal magnitude and opposite direction to the actual passive intermodulation interference cancels the actual passive intermodulation interference.

Based on the above basic principles, the process of passive intermodulation interference cancellation can be as shown in Figure 8. The steps are as follows:

S801: Determine a transmit signal that generates passive intermodulation interference;

It is necessary to use x and z as input signals to the canceller when performing passive intermodulation interference cancellation.

The PIM RXC is an example of the canceller shown in FIG.

The transmit signal that produces passive intermodulation interference is:

Tx=x+z*exp(j*(f _{TX_LO1} -f _{TX_LO0} )*t)

Where x is the transmit signal of one band as the input of the canceller (PIM RXC); z is the transmit signal of the other band as the input of the canceller (PIM RXC); f _{TX_LO0} is the radio frequency of the transmit channel corresponding to x The frequency of the vibration signal, f _{TX_LO1} is the frequency of the radio frequency local oscillator signal of the transmission channel corresponding to z, and t is time.

Both x and z need to be used as input signals to the canceller when performing passive intermodulation interference cancellation.

S802: selecting a multivariate nonlinear substrate;

There are many ways to express the multivariate nonlinear base, such as polynomial, segmented polyline, segmented spline, etc. The expression of the base has no direct influence on the offset of the passive intermodulation interference.

The multivariate nonlinear base is used as the multivariate polynomial expression as an example to illustrate the cancellation process of passive intermodulation interference.

S803: determining an expression form of the cancellation signal;

Since the passive intermodulation interference is related to the digital intermediate frequency transmission signal corresponding to multiple frequency bands, multiple passive intermodulation components are generated when performing passive intermodulation, and the intermodulation components may include the following forms:

Intermodulation components in the frequency band, such as:

The third-order intermodulation component between the bands is shaped as follows:

The fifth-order intermodulation component between the bands, like:

v=1, 2, 3, 4; h=5-v.

Where NL(|x|, |z|) denotes a multivariate nonlinear basis, conj() denotes a conjugate operation, f _{TX_LO0} represents the frequency of the local oscillator signal of the corresponding transmission channel of x, and f _{TX_LO1} represents the transmission channel corresponding to z The frequency of the local oscillator signal, f _{RX_LO0} represents the frequency of the local oscillator signal of the receiving channel corresponding to x. Here, the frequency of the local oscillator signal is equal to the center frequency of the transmitting band.

In the design of communication RF system, generally only focus on the intermodulation components below the fifth-order expression. The higher-order intermodulation components have little significance for the engineering of modeling cancellation because of the small composition.

The above-mentioned intermodulation components are combined with a specific frequency of transmission and reception, and one or more intermodulation components form a passive intermodulation interference of a certain receiving channel, so the frequency according to transmission and reception needs to be adopted. Point combination, which one or several intermodulation components are used for specific decisions; for example:

or

Where y is the output signal of the canceller, that is, the aforementioned cancellation signal.

Wherein, by determining the relative frequency relationship between the transmitting frequency band and the receiving frequency band, determining whether an intermodulation component will fall into the receiving frequency band after frequency shifting;

In various intermodulation components, f _{TX_LO0} -f _{RX_LO0} , f _{TX_LO1} -f _{RX_LO0} , 2f _{TX_LO0} -f _{TX_LO1} -f _{RX_LO0} are all frequency shift factors, and the frequency shift factor is in one-to-one correspondence with the expression of the nonlinear base.

The presence of the frequency shift factor embodies the frequency shifting process in the aforementioned step S602. The step performed by the multiplier before the input canceller PIM RXC in FIG. 7 is the frequency shift operation. In FIG. 7, the frequency shift factor is represented by ω ₀₀ , ω ₀₁ , ω ₁₀ , ω ₁₁ . For a detailed description of the frequency shifting, refer to the foregoing step S602.

The following intermodulation components are

The form is an example to illustrate the expression and solution of a multivariate nonlinear substrate.

S804: determining a coefficient of each of the plurality of nonlinear substrates;

A multivariate nonlinear substrate can be expressed as:

Where p is the number of times of the |x(t)| polynomial; P is the maximum number of times of the |x(t)| polynomial; q is the number of times of the |z(t)| polynomial; Q is the maximum of the polynomial of |z(t)| The number of times; ch _p,q is the coefficient of each nonlinear base in the multivariate nonlinear substrate.

To further enhance performance, add memory characteristics to multivariate nonlinear base expressions:

Where m is the delay value for the |x(t)| signal; M is the maximum delay value of the |x(t)| signal; n is the delay value for the |z(t)| signal; N is the pair |z( t) | The maximum delay value of the signal.

The offset error can be calculated by the following formula:

Where rx ₀ represents the received signal of the upper receiving channel in FIG. 7 (including the passive intermodulation interference signal); e ₀ represents the cancelled signal of the first receiving channel; k is the delay value of the x signal; K is the pair The maximum delay value of the x signal.

Optionally, the coefficient of the nonlinear base may be preset when the cancellation signal is generated for the first time, and the coefficient of the nonlinear base is adaptively solved according to the cancellation error of the last generation of the canceled passive intermodulation interference when the cancellation signal is generated subsequently. And updated in real time, the adaptive solution expression is:

Where ch _0,k,m,n,p,q (t) is the coefficient of the nonlinear base preset when the cancellation signal is first generated, and ch _0,k,m,n,p,q (t+1) is The coefficient of the nonlinear base generated after adaptively solving the previous cancellation error based on the next cancellation signal, mu is the step factor of the adaptive coefficient update process.

Optionally, in order to enhance the modeling in certain transmit bands (ie, multivariate nonlinear selection of substrates, multi-digital intermediate frequency transmit signals for frequency shifting and nonlinear transformation to simulate PIM interference falling into the receive band), The error signal and the nonlinear substrate can be narrowband filtered separately during the adaptive solution.

The process of performing adaptive solution can be as shown in FIG. Where NL ₁ , NL ₂ ... NL _PQR represents a nonlinear substrate in a multivariate nonlinear substrate.

Wherein, the general formula of the nonlinear substrate generating module is:

(xs) ^v *(conj(zs)) ^h *NL ₁ (|x|,|z|,|xz|)

(xs) ^v *(conj(zs)) ^h *NL ₂ (|x|,|z|,|xz|)

...

(xs) ^v *(conj(zs)) ^h *NL _PQR (|x|,|z|,|xz|)

In the application scenario shown in FIG. 7, the nonlinear base generation module is configured to be v=1, h=0.

In the adaptive solution process shown in FIG. 9, no memory characteristic is added to the transmitted signal. In practical applications, the memory characteristic can be added to the transmitted signal by setting a delay.

S805: Acquire a cancellation signal for canceling passive intermodulation interference.

The expression after adding the memory property to the canceler output is:

The offset of the passive intermodulation interference can be achieved by subtracting the canceler output from the actual received signal with passive intermodulation interference by using an adder connected to the canceler output y ₀ in FIG.

The passive intermodulation interference cancellation scheme shown in FIG. 7 is an example of the scheme shown in FIG. 5. The implementation scheme not described in detail in the scheme shown in FIG. 7 can refer to the description in the scheme shown in FIG. 5.

A passive intermodulation interference cancellation method in scenario 2 of a multi-antenna provided by the present application is described below with reference to FIG. 10, and FIG. 10 is an example of canceling passive intermodulation interference in a dual antenna scenario. In practice, multiple antennas are not limited to dual antennas.

The passive intermodulation interference in the dual antenna scene is related to the signals transmitted by the two antennas, that is, the two transmitted signals are radiated to the space at the antenna, and are radiated to the common passive intermodulation interference source after the spatial combination. It is a passive intermodulation interference containing two types of transmitted signals, which are then radiated into two receive channels.

The basic principle of canceling the passive intermodulation interference generated in the dual antenna scenario is: on the digital intermediate frequency side, the transmitted signals of the two antennas generate an interference with the actual passive intermodulation through the canceller (such as PIM RXC in Figure 10). Equal-sized, opposite-direction components that cancel the actual passive intermodulation interference.

Based on the above basic principle, the process of passive intermodulation interference cancellation can be as shown in FIG. 11, and the steps are as follows:

S1101: Calculating a transmit signal radiated to a common passive intermodulation interference source;

In Figure 10, the transmitted signal radiated to a common passive intermodulation interferer is:

Tx=(x+βe ^jθ z)

Where β is the combined amplitude factor, θ is the combined phase factor, x is the transmitted signal in one transmit channel, as the input to the canceller (PIM RXC), z is the transmit signal in the other transmit channel, acting as a canceller (PIM RXC) input.

Alternatively, x and z are co-frequency signals.

S1102: selecting a multivariate nonlinear substrate;

There are many ways to express multivariate nonlinear bases, such as polynomials, segmented polylines, and segmented splines. The expression of the base has no direct influence on the offset of passive intermodulation interference.

In the multi-antenna application scenario, the expression of the multivariate nonlinear substrate needs to reflect the amplitude and phase information in the combined process.

Take the following multivariate nonlinear substrate as an example to illustrate how to obtain the cancellation signal:

S1103: determining an expression form of the cancellation signal;

The wireless communication system generates multiple intermodulation components and the number of intermodulation components when performing passive intermodulation. The academic expression can be as follows:

Where v=0,1,2,3,h=0,1,2,3

_Wherein, f TX_LO0 frequency of the RF local oscillation signal to the transmit channel corresponding to _x, f RX_LO0 a frequency of the RF local oscillation signal corresponding to the channel received as above in FIG. 10. Here, the frequency of the local oscillator signal is equal to the center frequency of the transmitting frequency band;

There are many forms of expression of the cancellation signal, and the following one is taken as an example:

Where y is the cancellation signal, f _{TX_LO0} -f _{RX_LO0} is the frequency shift factor, and the frequency shift factor can be determined according to the expression form of the nonlinear base, and the expression forms of different nonlinear bases have different frequency shift factors. In different nonlinear substrate forms, the frequency shift factor w _Δ1 can be determined by the following general formula:

w _Δ1 =v*f _{TX_LO0} -h*f _{TX_LO1} -f _{RX_LO0}

Where f _{TX_LO1} is the frequency of the local oscillator signal of the transmission channel corresponding to z.

The presence of the frequency shift factor embodies the frequency shifting process in the aforementioned step S602. The step performed by the multiplier before the input canceller is the frequency shifting process in FIG. 10, wherein the frequency shift factor is represented by ω ₀₀ , ω ₀₁ , ω ₁₀ , ω ₁₁ . For a detailed description of the frequency shifting, refer to the foregoing step S602.

In order to enhance performance, on the basis of non-linear expression, increase memory characteristics:

Where k is the delay value for the x signal, K is the maximum delay value for the x signal, m is the delay value for the |x| signal, M is the maximum delay value of the |x| signal, and n is the signal for the |z| The delay value, N is the maximum delay value of the |z| signal, ch _{k,m,n,g,p,q,r} is the coefficient of the multivariate nonlinear base, and g is the delay value of the |x+βe ^jθ z| signal, G Is the maximum delay value of the |x+βe ^jθ z| signal.

S1104: determining a coefficient of each substrate in the multivariate nonlinear substrate;

When offsetting for passive intermodulation interference, the offset error is:

Err ₀ =rx ₀ -y ₀

Rx ₀ represents the actual received signal (including passive intermodulation interference) of the upper receiving channel in FIG.

Alternatively, the coefficients of each of the multivariate nonlinear substrates can be updated in real time by an adaptive solution, and the coefficients of the coefficients of each of the multivariate nonlinear substrates are:

Where ch _{0,k,m,n,g,p,q,r} (t) are the coefficients of the nonlinear base preset when the cancellation signal is first generated, ch _{0,k,m,n,g,p,q , r} (t+1) is the coefficient of the nonlinear base generated after adaptively solving the previous cancellation error when the cancellation signal is generated next, and mu is the step factor of the adaptive coefficient update process, and conj() Conjugate operation.

Optionally, in order to enhance the modeling in certain transmit bands (ie, selecting the base, performing frequency shifting, and performing nonlinear transformation to simulate PIM interference falling within the receive band), the adaptive solution may be separately performed. Narrow-band filtering of the error signal and the nonlinear substrate.

The process of performing adaptive solution can be as shown in FIG. Where NL ₁ , NL ₂ ... NL _PQ represent a nonlinear substrate in a multivariate nonlinear substrate.

Wherein, the general formula of the nonlinear substrate generating module is:

(xs) ^v *(conj(zs)) ^h *NL ₁ (|x|,|z|)

(xs) ^v *(conj(zs)) ^h *NL ₂ (|x|,|z|)

...

(xs) ^v *(conj(zs)) ^h *NL _PQ (|x|,|z|)

In the application scenario shown in FIG. 10, the nonlinear base generation module is configured to be v=1, h=0.

In the adaptive solution process shown in Figure 12, no memory characteristics are added to the transmitted signal, and the practical application The memory characteristic can be added to the transmitted signal by setting the delay.

S1105: Acquire a cancellation signal for canceling passive intermodulation interference.

The offset of the passive intermodulation interference can be achieved by subtracting the canceler output from the actual received signal with passive intermodulation interference by the adder connected to the canceler output y _{0 in} FIG.

The scheme shown in FIG. 10 can be regarded as an example of the scheme shown in FIG. 5. The embodiment not described in detail in the scheme shown in FIG. 10 can be described in the scheme shown in FIG. 5.

It should be noted that the passive intermodulation interference cancellation method and apparatus provided by the present application are not limited to application in multi-band RF combining and multi-antenna applications.

FIG. 13 is a schematic diagram of a passive intermodulation cancellation device provided by the present application. As shown in FIG. 13, the passive intermodulation cancellation device includes:

The acquiring module 1301 is configured to separately obtain a digital intermediate frequency transmission signal from multiple transmission channels;

The frequency shifting module 1302 is configured to obtain, according to the radio frequency band corresponding to each of the plurality of transmitting channels, the frequency interval of the radio frequency band corresponding to the different transmitting channels, and the radio frequency band corresponding to one of the plurality of receiving channels. The plurality of digital intermediate frequency transmission signals acquired by the module 1301 are respectively frequency-shifted, so that the radio frequency signals corresponding to the cancellation signals generated by the non-linear transformation of the plurality of digital intermediate frequency transmission signals after the frequency shift fall into the radio frequency receiving frequency band of the receiving channel. in;

The nonlinear transformation module 1303 is configured to perform nonlinear transformation on the plurality of digital intermediate frequency transmission signals after the frequency shifting module 1302 performs frequency shifting, and generate passive intermodulation interference for canceling the digital intermediate frequency reception signal on the receiving channel. Offset signal

The inverse superposition module 1304 is configured to inversely superimpose the generated cancellation signal on the digital intermediate frequency reception signal to cancel the passive intermodulation interference in the digital intermediate frequency reception signal.

Optionally, the non-linear transformation module 1303 is further configured to perform nonlinear transformation on the multi-channel digital intermediate frequency transmission signal after the frequency shifting module 1302 performs frequency shifting, and generate a digital intermediate frequency reception signal for canceling the received channel. Before the cancellation signal of the passive intermodulation interference, determine the multivariate nonlinear substrate used in the nonlinear transformation, the number of elements of the multivariate nonlinear substrate is equal to the number of channels of the plurality of transmission channels; determining each nonlinear substrate in the multivariate nonlinear substrate Coefficient of

The number of multiplexes after the frequency shift module 1302 performs frequency shifting by the nonlinear transform module 1303 When the word intermediate frequency transmission signal is nonlinearly transformed to generate a cancellation signal for canceling the passive intermodulation interference in the digital intermediate frequency reception signal on the receiving channel, the method is specifically used for: performing frequency shifting on the frequency shifting module 1302. The digital intermediate frequency transmission signal is operated according to the multivariate nonlinear substrate and the coefficients of each nonlinear substrate to obtain a cancellation signal for canceling the passive intermodulation interference in the digital intermediate frequency received signal on the receiving channel.

Optionally, the nonlinear transform module 1303 is configured to: when determining the coefficient of each of the nonlinear bases in the set of nonlinear substrates, specifically: when each of the canceling signals is generated, preset each nonlinear base in the multivariate nonlinear substrate Coefficient; when the cancellation signal is subsequently generated, the coefficients of each nonlinear base in the multivariate nonlinear substrate are calculated according to the error signal;

Optionally, each of the plurality of digital intermediate frequency transmission signals acquired by the acquisition module 1301 includes: a digital intermediate frequency transmission signal at a current time on a transmission channel where the digital intermediate frequency transmission signal is located; and/or the digital intermediate frequency transmission signal a digital intermediate frequency transmission signal at a plurality of times before the current time on the transmitting channel where the signal is located;

Optionally, the multiple transmit channels in which the plurality of digital intermediate frequency transmit signals acquired by the acquiring module 1301 are located are: the multiple transmit channels respectively correspond to different radio frequency bands; or the multiple transmit channels are connected to the same antenna, and the different transmit channels correspond to The antennas are polarized in different directions; or multiple transmitting channels are connected to different antennas, wherein one transmitting channel corresponds to one antenna; or multiple transmitting channels are connected through a radio frequency matrix network to connect multiple antennas.

Other alternative implementations of the passive intermodulation cancellation device can be implemented with reference to the implementation of the passive intermodulation cancellation device of FIGS. 5-12. The acquisition module 1301 can be used for acquisition operations, the frequency migration module 1302 can be used for frequency shift operations, the nonlinear transformation module 1303 can be used for nonlinear transformation operations, and the inverse overlay module 1304 can be used for reverse overlay operations. The other optional implementation manners of the acquisition module 1301 performing the acquisition operation may refer to the acquisition operations in FIG. 5 to FIG. 12 . Other optional implementation manners of the frequency shifting module 1302 performing the frequency shift operation may refer to the frequencies in FIG. 5 to FIG. 12 . Moving operation, nonlinear Other optional implementations of the transform module 1303 performing the non-linear transform operation may refer to the non-linear transform operations in FIG. 5 to FIG. 12, and other alternative implementations in which the inverse superimposition module 1304 performs the inverse superimposition operation may refer to FIG. 5 to FIG. Reverse stacking operation in 12.

FIG. 5 is a schematic structural diagram of the passive intermodulation interference canceling apparatus shown in FIG. 13 in an alternative implementation manner. The passive intermodulation interference cancellation device is coupled to a plurality of transmission channels and a reception channel of the communication device. As shown in FIG. 5, the passive intermodulation cancellation device includes:

The frequency shifting circuit 501 is configured to: according to the radio frequency band corresponding to each of the plurality of transmitting channels, the frequency interval of the radio frequency band corresponding to the different transmitting channels, and the radio frequency band corresponding to one of the plurality of receiving channels, The digital intermediate frequency transmission signals on each of the transmission channels are respectively frequency-shifted, so that the radio frequency signals corresponding to the cancellation signals generated by the non-linear transformation of the plurality of digital intermediate frequency transmission signals after the frequency shift fall into the receiving channel In the radio frequency receiving band;

The canceller 502 is configured to perform nonlinear transformation on the plurality of digital intermediate frequency transmission signals after the frequency shifting circuit 501 performs frequency shifting, and generate a cancellation signal for canceling passive intermodulation interference in the digital intermediate frequency received signal on the receiving channel. ;

The adder 503 is configured to inversely superimpose the cancellation signal generated by the canceller 502 on the digital intermediate frequency receiving signal received on the receiving channel to cancel the passive intermodulation interference in the digital intermediate frequency receiving signal, and superimpose the offset in the reverse direction. The digital intermediate frequency receiving signal output after the signal.

Optionally, the canceller 502 is further configured to: perform non-linear transformation on the multi-channel digital intermediate frequency transmission signal after the frequency shifting circuit 501 performs frequency shifting, and generate passive for canceling the digital intermediate frequency receiving signal on the receiving channel. Before intermodulating the canceling signal of the interference, determining the multivariate nonlinear substrate used in the nonlinear transformation, the number of elements of the multivariate nonlinear substrate is equal to the number of channels of the plurality of transmitting channels; determining the coefficient of each nonlinear substrate in the multivariate nonlinear substrate ;

The canceller 502 performs nonlinear conversion on the multi-channel digital intermediate frequency transmission signal after the frequency shifting circuit 501 performs frequency shifting, and generates a cancellation signal for canceling the passive intermodulation interference in the digital intermediate frequency received signal on the receiving channel. Specifically, the plurality of digital intermediate frequency transmission signals after frequency shifting by the frequency shifting circuit 501 are performed according to a multivariate nonlinear substrate and each nonlinear substrate. The coefficients are computed to obtain a cancellation signal for canceling passive intermodulation interference in the digital intermediate frequency received signal on the receive channel.

Optionally, the canceller 502 is configured to determine a coefficient of each nonlinear base in the multivariate nonlinear base when the cancel signal is generated for the first time when determining the coefficient of each nonlinear base in the set of nonlinear bases; When the cancellation signal is subsequently generated, the coefficients of each nonlinear substrate in the multivariate nonlinear substrate are calculated according to the error signal;

Optionally, multiple transmit channels respectively correspond to different radio frequency bands; or multiple transmit channels are connected to the same antenna, and different transmit channels have different antenna polarization directions; or multiple transmit channels are connected to different antennas, one of which The transmitting channel corresponds to one antenna; or the multiple transmitting channels are combined by the RF matrix network to connect multiple antennas.

The present application proposes a passive intermodulation interference cancellation scheme for a scenario in which multiple transmission channels exist, and passive intermodulation interference is related to signals transmitted on multiple transmission channels.

Passive intermodulation interference is the interference generated by the non-linear transformation between multiple transmitted RF signals caused by nonlinear devices, and the transmission between different transmission channels Passive intermodulation interference may also occur between frequency signals. In this application, considering the passive intermodulation interference that may occur between different transmission channels, the data intermediate frequency transmission signals are respectively obtained from multiple transmission channels to generate a cancellation signal for canceling the passive intermodulation interference. Effectively cancels passive intermodulation interference between multiple transmit channels.

Those skilled in the art will appreciate that the application can be provided as a method, system, or computer program product. Thus, the present application can take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment in combination of software and hardware. Moreover, the application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) including computer usable program code.

The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (system), and computer program products according to embodiments of the present application. It will be understood that each flow and/or block of the flowchart illustrations and/or FIG. These computer program instructions can be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing device to produce a machine for the execution of instructions for execution by a processor of a computer or other programmable data processing device. Means for implementing the functions specified in one or more of the flow or in a block or blocks of the flow chart.

The computer program instructions can also be stored in a computer readable memory that can direct a computer or other programmable data processing device to operate in a particular manner, such that the instructions stored in the computer readable memory produce an article of manufacture comprising the instruction device. The apparatus implements the functions specified in one or more blocks of a flow or a flow and/or block diagram of the flowchart.

These computer program instructions can also be loaded onto a computer or other programmable data processing device such that a series of operational steps are performed on a computer or other programmable device to produce computer-implemented processing for execution on a computer or other programmable device. The instructions provide steps for implementing the functions specified in one or more of the flow or in a block or blocks of a flow diagram.

Although a preferred embodiment of the present application has been described, one of ordinary skill in the art will recognize Additional changes and modifications to these embodiments can be made in the basic inventive concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and the modifications and

It is apparent that those skilled in the art can make various changes and modifications to the embodiments of the present application without departing from the spirit and scope of the embodiments of the present application. Thus, it is intended that the present invention cover the modifications and variations of the embodiments of the present invention.

Claims

A passive intermodulation interference cancellation device, characterized in that the device comprises:

An acquisition module, configured to respectively acquire digital intermediate frequency transmission signals from multiple transmission channels;

The frequency shifting module is configured to: according to the radio frequency band corresponding to each of the plurality of transmitting channels, the frequency interval of the radio frequency band corresponding to the different transmitting channels, and the radio frequency band corresponding to one of the plurality of receiving channels, The plurality of digital intermediate frequency transmission signals acquired by the acquiring module are respectively frequency-shifted, so that the radio frequency signals corresponding to the cancellation signals generated by the nonlinear transformation of the plurality of digital intermediate frequency transmission signals after the frequency shifting fall into the receiving channel In the radio frequency receiving band;

a non-linear transformation module, configured to perform the nonlinear transformation on the plurality of digital intermediate frequency transmission signals after frequency shifting by the frequency shifting module, and generate passive signals for canceling digital intermediate frequency reception signals on the receiving channel Intermodulating the cancellation signal of the interference;

And a reverse superposition module, configured to inversely superimpose the generated cancellation signal on the digital intermediate frequency reception signal to cancel passive intermodulation interference in the digital intermediate frequency reception signal.
The apparatus according to claim 1, wherein the non-linear transformation module is further configured to: perform nonlinear transformation on the multi-channel digital intermediate frequency transmission signal after the frequency shifting module performs frequency shifting, and generate the offset for generating Before the cancellation signal of the passive intermodulation interference in the digital intermediate frequency receiving signal on the receiving channel

Determining a multivariate nonlinear substrate used in performing the nonlinear transformation, the number of elements of the multivariate nonlinear substrate being equal to the number of channels of the plurality of transmission channels;

Determining coefficients of each of the nonlinear substrates in the multivariate nonlinear substrate;

The non-linear transformation module performs nonlinear transformation on the multi-channel digital intermediate frequency transmission signal after the frequency shifting module performs frequency shifting, and generates passive intermodulation interference for canceling the digital intermediate frequency reception signal on the receiving channel. When canceling the signal, it is specifically used to:

And the plurality of digital intermediate frequency transmission signals after the frequency shifting module performs frequency shifting are calculated according to the multivariate nonlinear base and the coefficient of each nonlinear base, thereby obtaining A cancellation signal of passive intermodulation interference in the digital intermediate frequency received signal on the receiving channel is cancelled.
The apparatus of claim 2, wherein the nonlinear transform module is specifically configured to: when determining a coefficient of each of the nonlinear bases in the set of nonlinear substrates:

Determining a coefficient of each of the nonlinear bases in the multivariate nonlinear substrate when the cancellation signal is first generated;

When subsequently generating the cancellation signal, calculating a coefficient of each nonlinear base in the multivariate nonlinear substrate according to the error signal;

The error signal is the difference between the received digital intermediate frequency received signal and the previously generated canceled signal.
The apparatus according to any one of claims 1 to 3, wherein each of the plurality of digital intermediate frequency transmission signals acquired by the acquisition module comprises:

a digital intermediate frequency transmission signal at a current time on a transmission channel in which the digital intermediate frequency transmission signal is located; and/or

a digital intermediate frequency transmission signal at a plurality of times before the current time on the transmission channel where the digital intermediate frequency transmission signal is located;

The current time is a time at which the generated cancellation signal is inversely superimposed on the digital intermediate frequency reception signal.
The apparatus according to any one of claims 1 to 4, wherein the plurality of transmission channels in which the plurality of digital intermediate frequency transmission signals acquired by the acquisition module are located meets:

The plurality of transmission channels respectively correspond to different radio frequency bands; or

The plurality of transmitting channels are connected to the same antenna, and the antennas of different transmitting channels have different polarization directions; or

The plurality of transmitting channels are connected to different antennas, wherein one of the transmitting channels corresponds to one antenna; or

The plurality of transmitting channels are connected to the plurality of antennas after being combined by the radio frequency matrix network.
A passive intermodulation interference cancellation method, comprising:

Obtaining a digital intermediate frequency transmission signal from each of the plurality of transmission channels;

And obtaining a plurality of digital intermediate frequencies according to a radio frequency band corresponding to each of the plurality of transmitting channels, a frequency interval of the radio frequency band corresponding to the different transmitting channels, and a radio frequency band corresponding to one of the plurality of receiving channels The transmitting signals are respectively frequency-shifted, so that the radio frequency signals corresponding to the canceling signals generated by the non-linear transformation of the plurality of digital intermediate frequency transmitting signals after the frequency shifting fall into the radio frequency receiving frequency band of the receiving channel;

Performing the nonlinear transformation on the plurality of digital intermediate frequency transmission signals after frequency shifting to generate the cancellation signal for canceling passive intermodulation interference in the digital intermediate frequency reception signal on the receiving channel;

The generated cancellation signal is inversely superimposed on the digital intermediate frequency received signal to cancel passive intermodulation interference in the digital intermediate frequency received signal.
The method of claim 6 wherein the multi-channel digital intermediate frequency transmission signal after frequency shifting is nonlinearly transformed to generate passive intermodulation interference for canceling the digital intermediate frequency received signal on the receiving channel. Before canceling the signal, it also includes:

Determining a multivariate nonlinear substrate used in performing the nonlinear transformation, the number of elements of the multivariate nonlinear substrate being equal to the number of channels of the plurality of transmission channels;

Determining coefficients of each of the nonlinear substrates in the multivariate nonlinear substrate;

The multi-channel digital intermediate frequency transmission signal after the frequency shift is nonlinearly transformed to generate a cancellation signal for canceling the passive intermodulation interference in the digital intermediate frequency reception signal on the receiving channel, including:

Performing the plurality of digital intermediate frequency transmission signals after the frequency shifting according to the multivariate nonlinear substrate and the coefficients of each nonlinear base to obtain a passive mutual in canceling the digital intermediate frequency receiving signal on the receiving channel Adjust the interference cancellation signal.
The method of claim 7 wherein determining coefficients of each of said set of non-linear substrates comprises:

Determining a coefficient of each of the nonlinear bases in the multivariate nonlinear substrate when the cancellation signal is first generated;

When subsequently generating the cancellation signal, calculating a coefficient of each nonlinear base in the multivariate nonlinear substrate according to the error signal;

The error signal is the difference between the received digital intermediate frequency received signal and the previously generated canceled signal.
The method according to any one of claims 6 to 8, wherein each of the plurality of digital intermediate frequency transmission signals comprises:

a digital intermediate frequency transmission signal at a current time on a transmission channel in which the digital intermediate frequency transmission signal is located; and/or

a digital intermediate frequency transmission signal at a plurality of times before the current time on the transmission channel where the digital intermediate frequency transmission signal is located;

The current time is a time at which the generated cancellation signal is inversely superimposed on the digital intermediate frequency reception signal.
A method according to any one of claims 6 to 9, wherein

The plurality of transmission channels respectively correspond to different radio frequency bands; or

The plurality of transmitting channels are connected to the same antenna, and the antennas of different transmitting channels have different polarization directions; or

The plurality of transmitting channels are connected to different antennas, wherein one of the transmitting channels corresponds to one antenna; or

The plurality of transmitting channels are connected to the plurality of antennas after being combined by the radio frequency matrix network.