CN116266920A

CN116266920A - Intermodulation correction method and device

Info

Publication number: CN116266920A
Application number: CN202111552202.3A
Authority: CN
Inventors: 杨斌; 于香起; 赵兴; 童浩然
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2021-12-17
Filing date: 2021-12-17
Publication date: 2023-06-20

Abstract

The embodiment of the application provides a method and a device for intermodulation correction, which are applied to a distributed base station, wherein the distributed base station comprises a convergence unit and a remote radio unit, the convergence unit comprises a first processing unit, a transmitting end and a receiving and combining unit, and the method comprises the following steps: the first processing unit receives a first correction signal, wherein the first correction signal is a transmitting signal or the first correction signal is a signal received from a receiving channel, and the first intermodulation interference signal is obtained by combining a second intermodulation interference signal received from the remote radio unit by the receiving combining unit; the first processing unit carries out nonlinear cancellation on the first correction signal and then outputs a second correction signal, wherein the second correction signal is used for subtracting or adding the first intermodulation interference signal or sending the first intermodulation interference signal to the receiving channel, and the receiving channel sends the signal to the first processing signal, namely the first correction signal of the next cycle. The method and the device provided by the application can effectively reduce the processing cost and save the resources.

Description

Intermodulation correction method and device

Technical Field

Embodiments of the present application relate to the field of communications, and more particularly, to a method and apparatus for intermodulation correction.

Background

In a wireless communication system, a baseband processing unit (BBU) executes a baseband algorithm, and can interact with an RRU through a common public radio interface (common public radio interface, CPRI) interface, and then a remote radio unit (radio remote unit, RRU) transmits a downlink transmission signal to an antenna through a feeder line. However, intermodulation, such as passive inter-modulation (PIM) or active interference, may occur between the multiple downstream transmit signals due to non-ideal factors such as cables, diplexers, or antenna feeds. Under certain frequency point configurations, the intermodulation frequency may be the same as or similar to the frequency of the useful signal, and the low-order intermodulation generated by the downlink transmission signal hits the uplink receiving frequency band, that is, the frequency of the generated intermodulation interference is wholly or partially overlapped with the frequency of the uplink receiving, so that an interference is caused to the communication system.

For example, to address active intermodulation, it can be addressed by DUP with high isolation, but also affects module output power consumption; or, with the explicit cancellation scheme, a feedback channel needs to be set to realize, which increases the processing cost. For another example, in order to solve passive intermodulation, each module independently performs one-to-one nonlinear cancellation, so that the deployment cost is high and the resource consumption is high. Moreover, as the number of channels in the distributed base station increases, the cost of active intermodulation and passive intermodulation is increased, and the power consumption and cost of the module are also increased, so how to realize intermodulation correction with low cost and low power consumption in a multi-RRU combining scene becomes a problem to be solved.

Disclosure of Invention

The embodiment of the application provides an intermodulation correction method, which can effectively reduce processing cost and save resources.

In a first aspect, a method for intermodulation correction is provided, which is applied to a distributed base station, and is characterized in that the distributed base station includes a convergence unit and a remote radio unit, the convergence unit includes a first processing unit, a transmitting end, and a receiving and combining unit, and the method includes:

the first processing unit receives a first correction signal, wherein the first correction signal is a transmitting signal from the transmitting end, or the first correction signal is a signal obtained by subtracting or adding a signal output by the first processing unit and a first intermodulation interference signal output by the receiving and combining unit, and the first intermodulation interference signal is obtained by combining a second intermodulation interference signal received from the remote radio unit by the receiving and combining unit;

the first processing unit outputs a second correction signal according to the first correction signal, the second correction signal is obtained by the first processing unit after nonlinear cancellation of the first correction signal, and the second correction signal is used for subtracting or adding with the first intermodulation interference signal.

According to the scheme, intermodulation interference and feedback channel removal are solved by using the centralized resource pool, so that the processing cost can be effectively reduced and resources can be saved.

With reference to the first aspect, in certain implementation manners of the first aspect, the method further includes:

the first processing unit receives an ith first correction signal, wherein the ith first correction signal is obtained by adding or subtracting an ith-1 second correction signal from an ith-1 first intermodulation interference signal, and i is a positive integer greater than 1;

the first processing unit outputs an ith second correction signal according to the ith first correction signal, wherein the ith second correction signal is obtained by the first processing unit after nonlinear cancellation of the ith second correction signal.

With reference to the first aspect, in some implementations of the first aspect, the first processing unit sends indication information to the remote radio unit, where the indication information is used to indicate processing of a received signal, and the processing includes performing linear cancellation or non-linear cancellation on the received signal to obtain the second intermodulation interference signal.

In a second aspect, a method for intermodulation correction is provided, which is applied to a distributed base station, and is characterized in that the distributed base station includes a convergence unit and a remote radio unit, and the remote radio unit includes at least 2 modules, and the method includes:

The remote radio unit receives indication information from the aggregation unit, wherein the indication information is used for indicating the received signal to be processed;

the remote radio unit processes at least 2 received signals according to the indication information to obtain at least 2 second intermodulation interference signals, wherein each second intermodulation interference signal is obtained by processing 1 received signal by each module, the processing comprises linear intermodulation or nonlinear intermodulation, and the at least 2 second intermodulation interference signals can be subjected to nonlinear cancellation processing by a first processing unit in the convergence unit;

and the remote radio unit sends the at least 2 second intermodulation interference signals to the convergence unit.

In a third aspect, an intermodulation correction apparatus is provided, which is characterized in that the apparatus includes a convergence unit and a remote radio unit, the convergence unit includes a first processing unit, a transmitting end, and a receiving and combining unit,

the first processing unit is configured to receive a first correction signal, where the first correction signal is a transmission signal from the transmitting end, or the first correction signal is a signal obtained by subtracting or adding a signal output by the first processing unit and a first intermodulation interference signal output by the receiving and combining unit, where the first intermodulation interference signal is obtained by combining, by the receiving and combining unit, a second intermodulation interference signal received from the remote radio unit, and the second intermodulation interference signals are respectively from different modules of the remote radio unit;

The first processing unit is further configured to output a second correction signal according to the first correction signal, where the second correction signal is obtained by the first processing unit after performing nonlinear cancellation on the first correction signal, and the second correction signal is used to subtract or add the first intermodulation interference signal.

With reference to the third aspect, in certain implementation manners of the third aspect, the first processing unit is further configured to receive an ith first correction signal, where the ith first correction signal is obtained by adding or subtracting an ith-1 th first intermodulation interference signal from an ith-1 st second correction signal, and i is a positive integer greater than 1;

the first processing unit is further configured to output an ith second correction signal according to the ith first correction signal, where the ith second correction signal is obtained by performing nonlinear cancellation on the ith second correction signal by the first processing unit.

With reference to the third aspect, in some implementations of the third aspect, the first processing unit is further configured to send indication information to the remote radio unit, where the indication information is used to indicate processing of a received signal, and the processing includes performing linear cancellation or non-linear cancellation on the received signal to obtain the at least 2 second intermodulation interference signals.

In a fourth aspect, an apparatus for intermodulation correction is provided, which is characterized by comprising a convergence unit and a remote radio unit, wherein the remote radio unit comprises at least 2 modules,

the remote radio unit is used for receiving the indication information from the aggregation unit, and the indication information is used for indicating the received signal to be processed;

the remote radio unit is further configured to process at least 2 received signals according to the indication information to obtain at least 2 second intermodulation interference signals, where each second intermodulation interference signal is obtained by processing 1 received signal by each module, the processing includes linear intermodulation or nonlinear intermodulation, and the at least 2 second intermodulation interference signals may be subjected to nonlinear cancellation by a first processing unit in the aggregation unit;

the remote radio unit is further configured to send the at least 2 second intermodulation interference signals to the convergence unit.

In a fifth aspect, a communication system is provided, characterized in that the communication system comprises an apparatus according to the third or fourth aspect.

In a sixth aspect, a distributed base station is provided, which includes: the apparatus according to the third or fourth aspect and a baseband unit.

In a seventh aspect, there is provided an optical communication apparatus comprising: a processor and a communication interface through which the processor is coupled to a memory, the processor being operable to execute program code in the memory to implement the method of the first or second aspect.

In an eighth aspect, a chip is provided, characterized in that the chip comprises programmable logic circuits and/or program instructions for implementing the method according to the first or second aspect when the chip is run.

A ninth aspect provides a computer-readable storage medium, comprising: the computer readable storage medium stores a computer program which, when run on the computer, causes the computer to perform the method of the first or second aspect.

In a tenth aspect, there is provided a computer program, characterized in that the computer program, when executed on a computer, causes the computer to perform the method according to the first or second aspect.

Drawings

Fig. 1 is a schematic architecture diagram of a distributed base station.

Fig. 2 shows a schematic block diagram of an example of the basic structure of a distributed base station.

Fig. 3 shows an example of the principle of intermodulation correction by a distributed base station.

Fig. 4 illustrates a method 100 of intermodulation correction provided herein.

Fig. 5 shows an example of the basic principle of intermodulation correction provided in the present application.

Fig. 6 shows a schematic diagram of still another example of the basic principle of intermodulation correction provided in the present application.

FIG. 7 is a schematic diagram showing an example of intermodulation correction apparatus to which the present application is applied

Fig. 8 is another exemplary view of an intermodulation correction apparatus to which the present application is applied.

Detailed Description

The technical solutions in the present application will be described below with reference to the accompanying drawings.

The technical solution of the embodiment of the application can be applied to various communication systems, for example: a fifth generation (5th generation,5G) system or New Radio (NR), a long term evolution (long term evolution, LTE) system (e.g., an LTE frequency division duplex (frequency division duplex, FDD) system, an LTE time division duplex (time division duplex, TDD)), etc. In addition, the technical scheme of the embodiment of the application can be applied to side link communication. For example, the technical solution of the embodiment of the present application may also be applied to: device-to-device (D2D) communication, machine-to-machine (machine to machine, M2M) communication, machine type communication (machine type communication, MTC), and communication in a car networking system.

For ease of understanding, an example architecture diagram of a distributed base station capable of implementing the communication methods of embodiments of the present application will be described generally. It should be understood that the embodiments of the present application are not limited to the system architecture shown in fig. 1, and the system to which the signal processing method and the distributed control apparatus of the embodiments of the present application may be applied may further include other devices or units, and in addition, the apparatus in fig. 1 may be hardware, or may be functionally divided software or a combination of the two.

The BBU110 is a baseband processing unit (BBU), and centrally controls and manages the entire base station system and implements baseband signal processing. DCU 120 supports RF source feeds and may also receive signals transmitted by BBU 110. The base transceiver station (base transceiver station, BTS) 130 may RF feed the DCU 120 with signals.

pRRU 150 is an indoor low-power remote radio unit (radio remote unit, RRU) responsible for transmitting and processing radio frequency signals between BBU110 or BTS 130 and the antenna feeder system.

Currently, a large amount of network systems use a distributed base station architecture, and optical fiber connection is needed between an RRU (remote radio unit) and a BBU (baseband processing unit) in a distributed base station. One BBU may support multiple RRUs.

Specifically, in the wireless communication system, the wireless communication base station system executes a baseband algorithm by the BBU, and can interact baseband signals with the RRU through a common public radio interface (common public radio interface, CPRI) interface, and then the RRU transmits downlink transmission signals to the antenna through a feeder line. However, intermodulation, such as passive inter-modulation (PIM), may occur between multiple downstream transmit signals due to non-ideal factors such as cables, diplexers, or antenna feeds, among other analog devices. Under certain frequency point configurations, the intermodulation frequency may be the same as or similar to the frequency of the useful signal, and the low-order intermodulation generated by the downlink transmission signal hits the uplink receiving frequency band, that is, the frequency of the generated intermodulation interference is wholly or partially overlapped with the frequency of the uplink receiving, so that an interference is caused to the communication system.

For convenience of explanation of the present solution, some technical terms related to the present application are described below.

1. Radio frequency amplifier (radio frequency power amplifier, RF PA): the main device of the transmitting path of the front end of the radio frequency is mainly used for amplifying the low-power radio frequency signal generated by the modulating oscillating circuit to obtain enough radio frequency output power which can be fed to an antenna to radiate, and is usually used for amplifying the radio frequency signal of the transmitting channel.

2. Duplexer (DUP): the duplexer is a main accessory of a different-frequency duplex radio station and a relay station, and has the function of isolating the transmitted and received signals and ensuring that the receiving and the transmitting can work normally at the same time. The device consists of two groups of band-pass filters with different frequencies, and avoids the transmission of local transmitting signals to a receiver.

3. Antenna (antenna, ANT): an antenna is a transducer that converts a guided wave propagating on a transmission line into an electromagnetic wave propagating in an unbounded medium (usually free space) or vice versa. A component for transmitting or receiving electromagnetic waves in a radio device. Engineering systems such as radio communication, broadcasting, television, radar, navigation, electronic countermeasure, remote sensing, radio astronomy and the like all rely on antennas to work when information is transmitted by electromagnetic waves. In addition, in terms of energy transfer with electromagnetic waves, an antenna is also required for energy radiation other than signals. The common antennas are reversible, i.e. the same pair of antennas can be used as both a transmitting antenna and a receiving antenna. The same antenna is the same as the basic characteristic parameters of transmission or reception. This is the reciprocal theorem of antennas.

4. A combiner: the combiner is mainly used for a receiving end and is used for combining two or more paths of radio frequency signals sent by different remote units into one path to be sent to the baseband unit, and meanwhile, the mutual influence among all port signals is avoided.

5. Intermodulation interference: intermodulation, such as passive intermodulation, can occur between multiple downstream transmit signals due to non-idealities of some analog devices, such as cables, diplexers, or antenna feeds. Under certain frequency point configurations, the intermodulation frequency may be the same as or similar to the frequency of the useful signal, and the low-order intermodulation generated by the downlink transmission signal hits the uplink receiving frequency band, that is, the frequency of the generated intermodulation interference is wholly or partially overlapped with the frequency of the uplink receiving, so that an interference is caused to the communication system.

6. Active intermodulation: intermodulation generated by the active device is active intermodulation.

7. Passive inter-modulation (PIM): passive intermodulation is similar to active intermodulation except that passive intermodulation is generated by passive devices. Intermodulation is created whenever two or more RF signals are present simultaneously in one radio frequency conductor. When more than one frequency is present in the device, any passive device will produce passive intermodulation products. Due to the non-linearities at the junction of the different materials, the signals will mix at the junction. Typically, the odd-order intermodulation products (i.e., im3=2xf1-F2) fall within the uplink or receive frequency band of the base station and become signals that interfere with the operation of the receiver. It can cause receiver desensitization independent of the random noise floor of the receiver.

8. Intermodulation distortion (intermodulation distortion, IMD): intermodulation distortion refers to the sum and difference distortion of an input signal introduced by an amplifier. For example, intermodulation distortion components are generated after the mixed signal is input to the amplifier. Intermodulation distortion refers to distortion caused by intermodulation of signals, and the term modulation refers to a technique used in communication technology to improve signal transmission efficiency. The original signal containing sound, image, text, etc. is "added" to the high frequency signal, and then the resultant signal is transmitted. This process and manner of adding the high and low frequency phases is referred to as modulation techniques, and the resultant signal is referred to as a modulated signal. The modulated signal contains all information of the low frequency signal in addition to the main characteristics of the high frequency signal. The intermodulation distortion generating process is also a modulation process, because an electronic circuit or an amplifier cannot achieve perfect linearity, when signals with different frequencies enter the amplifier at the same time and are amplified, under the nonlinear effect, signals with different frequencies are automatically added and subtracted to generate two additional signals which are not in the original signals, the original signals have three different frequencies, the number of the additional signals is 6, and when the original signals are N, the number of the output signals is N (N-1). It is conceivable that the amount of extra signal generated by intermodulation distortion is quite dramatic when the input signal is a complex multi-frequency signal, such as an orchestra.

9. Linear cancellation: and solving the interference cancellation problem by linear fitting by utilizing the linear correlation relationship between the reference signal and the interference signal.

10. Nonlinear cancellation: and the nonlinear relation between the reference signal and the interference signal is utilized, and the nonlinear fitting is utilized to solve the interference cancellation problem.

The units and modules involved in the distributed base station are further described below in connection with fig. 2. Fig. 2 shows a schematic block diagram of an example of the basic structure of a distributed base station.

As shown in fig. 2, the transmitting end Tx of the convergence module transmits signals to the transmitting end Tx of the RRU, the RRU transmits signals received by the receiving end Rx to the Rx combining circuit of the convergence unit (convergence element, CE) through the receiving channel of the RRU, and then the convergence unit processes the received signals and transmits the processed signals to the BBU. Specifically, in RRU, taking module 1 as an example, the transmitting terminal Tx receives a signal 01, transmits the signal to the RF PA, processes the signal and transmits the signal to the DUP, and processes the DUP and transmits the signal through the ANT; the nonlinear cancellation processing unit performs nonlinear cancellation processing on a transmitting signal received from the transmitting end Tx and then outputs a signal, the signal received by the receiving end Rx and the signal output by the nonlinear cancellation processing unit are subtracted to obtain error, the error is sent to the receiving channel, the output error is subtracted from the signal received by the receiving end Rx by the nonlinear model cancellation processing unit and then is sent to the receiving channel, and the process is repeated according to the flow until the receiving channel sends the appropriate signal to the Rx combining channel of the converging unit.

It should be noted that, in fig. 2, the RRU is illustrated by taking the module 1 and the module 2 as examples, but the number of modules in the RRU is not limited in this application.

Since RF PA, DUP or ANT can cause intermodulation active or passive intermodulation between a plurality of downlink transmission signals, intermodulation interference is generated, and sensitivity of a receiving end is affected. The current common intermodulation correction method is to deploy a nonlinear module cancellation processing unit or a linear cancellation processing unit in the RRU to solve the intermodulation interference problem. At present, radio frequency combining by multiple RRUs belongs to a common technology, and intermodulation correction is generally performed in RRUs by linear cancellation or nonlinear cancellation one-to-one with modules in a multiple RRU combining scene.

Some intermodulation correction schemes are described below in connection with fig. 3, in terms of solving both active intermodulation and passive intermodulation, respectively.

In order to solve the active intermodulation, the active intermodulation can be solved by a DUP with high isolation, but the output power consumption of the module can be influenced; alternatively, with explicit cancellation schemes, the feedback paths (e.g., between PA and DUP, between DUP and Rx in fig. 3) need to be set to achieve this, which increases processing costs. In order to solve passive intermodulation, each module independently performs one-to-one nonlinear cancellation (for example, a nonlinear module cancellation processing unit is arranged in each of the module 1 and the module 2 in fig. 3), so that the deployment cost is high, and the resource consumption is also high. Moreover, as the number of channels in the distributed base station increases, the cost of active intermodulation and passive intermodulation is increased, and the power consumption and cost of the module are also increased, so how to realize intermodulation correction with low cost and low power consumption in a multi-RRU combining scene becomes a problem to be solved.

The method 100 of intermodulation correction provided herein is described below in conjunction with fig. 4. Fig. 4 is a schematic flowchart of a method 100 for intermodulation correction provided in an embodiment of the present application, where the method is applied to a distributed base station, and the distributed base station includes a convergence unit and a remote radio unit, where the convergence unit includes a first processing unit, a transmitting end, and a receiving and combining unit. The method 100 specifically includes the steps of:

s101, the first processing unit receives a first correction signal.

The first processing unit may be, for example, a nonlinear model cancellation processing unit in the convergence unit in fig. 5 to 6, and the description of the nonlinear model cancellation processing unit may be specifically referred to in the corresponding descriptions in fig. 5 and 6.

S102, the first processing unit outputs a second correction signal according to the first correction signal.

The second correction signal is obtained by the first processing unit after nonlinear cancellation of the first correction signal. The description of nonlinear cancellation can be found in detail in fig. 5 and 6.

It should be appreciated that in the method 100, S101 and S102 are performed M times, where M is a positive integer greater than or equal to 2.

When the first time is performed, the first correction signal in S101 is a transmission signal from the transmitting end. From the M-th execution (i is a positive integer greater than 1 and less than or equal to M), the first correction signal in S101 is a signal obtained by subtracting or adding the signal output by the first processing unit and the first intermodulation interference signal output by the receive combining unit. The signal output by the first processing unit is the i-1 th second correction signal output by the i-1 st time. The i-1 th second correction signal and the first intermodulation interference signal are added or added to obtain a signal, the signal is sent to the first processing unit through a receiving channel of the converging unit, the signal sent to the first processing unit by the receiving channel is the i-th first correction signal, and then the i+1th cycle is continued.

The second intermodulation interference signal may be a different module from the remote radio unit, for example, in fig. 3, and it is possible that the second intermodulation interference signal 01 is sent by the module 1 of the RRU to the Rx combining of the convergence unit through the receiving channel, and the second intermodulation interference signal 02 is sent by the module 2 to the Rx combining of the convergence unit through the receiving channel.

Optionally, the remote radio unit includes at least 2 modules, and the method 100 further includes:

step 1: the first processing unit sends indication information to the remote radio unit, and accordingly, the remote radio unit receives the indication information from the aggregation unit, wherein the indication information is used for indicating to process the received signal, and the processing comprises the steps of performing linear cancellation or nonlinear cancellation on the received signal to obtain a second intermodulation interference signal.

It should be understood that the indication information may be sent or transmitted by the convergence unit to the remote radio unit through the control unit, or the control unit may be implemented by a virtual interface between the remote radio unit and the convergence unit.

Step 2: the remote radio unit processes at least 2 received signals according to the indication information to obtain at least 2 second intermodulation interference signals, wherein each second intermodulation interference signal is obtained by processing 1 received signal by each module, the processing comprises linear intermodulation or nonlinear intermodulation, and the at least 2 second intermodulation interference signals can be subjected to nonlinear cancellation by a first processing unit in the convergence unit.

It should be appreciated that each module of the remote radio unit processes the received signal and each module obtains a second intermodulation interference signal, but the processing performed by each module may not be the same as the second intermodulation interference signal obtained. For example, each module may include a transmitting end, a receiving end, a radio frequency amplifier, a duplexer, an antenna, and the like, and the differences of signals received by the receiving ends of different modules may be different due to the fact that hardware differences may exist between the devices of different modules. If the difference is a non-linear difference, such as a difference caused by a non-linear constituent mechanism of the device, etc., then the processing of the module needs to include a non-linear fit, and if the difference is a linear difference, such as flatness, delay jitter, etc., then the processing of the module needs to include a non-linear fit.

It should also be appreciated that the second intermodulation interference signal obtained by each module may be fitted non-linearly by the same non-linear model, and the first processing unit of the aggregation unit is the non-linear module, whether or not the received signal and the processing of the received signal are identical, before the second intermodulation interference signal is obtained.

Step 3: the remote radio unit sends at least 2 second intermodulation interference signals to the convergence unit.

The remote radio unit sends the second intermodulation interference signal to the receiving combiner of the convergence unit, and the convergence unit receives the second intermodulation interference signal correspondingly, and the subsequent steps can be specifically described in S102.

In summary, compared with the method that each module independently performs one-to-one nonlinear cancellation processing, according to the scheme, after each module in the RRU calculates the nonlinear difference part caused by the difference part of the radio frequency device in intermodulation interference, the nonlinear difference part is sent to the convergence unit to perform centralized nonlinear fitting of resource pooling, so that the plurality of modules in the common cell complete the cancellation processing under the cooperation of the convergence unit, the modules and algorithms of the nonlinear model cancellation processing unit deployed by each module can be greatly simplified, the deployment cost is reduced, the resource consumption is reduced, and even under the condition that the number of channels in the distributed base station is continuously increased, the cost is reduced and the resources are saved. Compared with the arrangement of feedback channels among a plurality of radio frequency devices, the scheme does not need to arrange the feedback channels, and further saves processing cost. Compared with the duplexer with high isolation, the duplexer with high isolation is not needed to be arranged in the scheme, the influence on the output function of the module is avoided, the cost is further reduced, and resources are saved.

Therefore, the scheme solves intermodulation interference and a feedback channel by using the centralized resource pool, and can effectively reduce processing cost and save resources.

Having described the method 100 of intermodulation correction provided herein, the principles of intermodulation correction provided herein are described below.

The overall design scheme may be summarized as that a simplified linear/nonlinear model cancellation processing unit is deployed in each module of the RRU, and is configured to process a difference portion of the first IDM generated by a different module caused by a hardware performance difference between each module, so that the output second IMD may be processed by the same nonlinear module cancellation unit. Each module in the RRU sends the output second IMD to the aggregation unit, the nonlinear cancellation processing unit of the aggregation unit processes the second IMD, and the processed signals are sent to the BBU. It should be understood that, because different modules in the RRU have different factory times and different batches, there is a difference in hardware performance between the modules, and also there is a difference in IMD generated by the different modules. Wherein the difference portion of the IMDs generated by the different modules includes a linear difference portion and a non-linear difference portion.

It should also be appreciated that the intermodulation correction scheme provided herein requires a cascade of combining modules and nonlinear modules of the remote unit.

An exemplary schematic diagram of the basic principle of intermodulation correction provided in the present application is described below with reference to fig. 5.

As shown in fig. 5, the convergence unit may determine, based on the application needs of the scene or the actual product, that the nonlinear model cancellation processing unit of the convergence unit and the simplified nonlinear model cancellation processing units in the modules of the RRU need to perform several solutions on the received signal to ensure that the final error is minimum, for example, two thresholds may be set, and when the number of times the nonlinear model cancellation processing unit of the convergence unit performs the solution on the received signal reaches the first threshold, the solution is stopped, and when the number of times the simplified nonlinear model of the modules of the RRU performs the solution on the received signal reaches the second threshold, the solution is stopped. The second threshold may be sent to the modules of the RRU by the control unit, and when the modules of the RRU start to resolve may also be triggered by an indication sent by the control unit. From the above, the convergence unit controls the RRU through the control unit, and the control path of the control unit is indicated by a dotted line in fig. 5, which is intended to be expressed in a specific implementation, and may be implemented through a virtual interface between the convergence unit and the RRU. Similarly, the nonlinear model cancellation processing unit of the convergence unit and the simplified nonlinear model cancellation processing unit of the module 2 in the RRU may also be controlled by a control unit, which is not shown in fig. 5.

Subsequently, the transmitting end Tx of the aggregation unit distributes the transmission signal X to the modules 1 and 2 in the RRU. Taking module 1 as an example, the transmitting end Tx of module 1 receives the signal f output after the signal X passes through the reduced nonlinear model cancellation processing unit ₁ (x) Subtracting the signal Y received by the module 1 from the receiving end Rx, Y-f ₁ (x) The receiving channel feeds back to the simplified nonlinear model cancellation processing unit to continue to calculate to obtain f ₁ 'x' continues to be subtracted from the signal Y, f ₁ ’(x)＝f ₁ (Y-f ₁ (x) After m-2 is recycled according to the procedure (e.g. m is the second threshold value allocated to the RRU by the aggregation unit, m is a positive integer), the receiving channel of module 1 outputs the signal f ₁ ^m (x) Receive combining to the aggregation unit. Similarly, the simplified nonlinear cancellation processing unit in the module 2 also circulates the above-mentioned procedure n (for example, m is a second threshold value configured to the RRU by the convergence unit, m is a positive integer, and m may or may not be equal to n) times, and then sends f through the receiving channel ₂ ⁿ (x) And a receive combiner for sending to the aggregation unit. Wherein the simplified nonlinear model of each module can identify nonlinear constitution mechanisms of different modules and key influencing factors of different devices, and perform corresponding nonlinear fitting, wherein the nonlinear fitting is only Occupies a small portion of the entire intermodulation correction flow, and may be, for example, less than 20% of it. In particular, the non-linear fitting process herein deals with how much of the proportion of intermodulation in the received signal is determined from the instructions sent by the aggregation unit through the control unit. It should be noted that, in fig. 2, the RRU is illustrated by taking the module 1 and the module 2 as examples, but the present application does not limit the number of modules in the RRU, and it is assumed that the RRU includes L modules, where L is greater than or equal to 2.

Illustratively f ₁ (x) Or f ₂ (x) Can be equal to a0 x _n *abs(x _n )+a1*x _n-1 *abs(x _n-1 )+a2*x _n-2 *abs(x _n-2 ) + … … where the argument x _n Representing the delay of the transmitted signal X at time n, X _n-1 Representing the delay of the transmitted signal X at time n-1, abs (X _n ) Representation of pair x _n Take absolute value by the method of [ a ] ₀ a ₁ …a _n ]*X＝f ₁ (x)，[a ₀ a ₁ …a _n ]*f ₁ (x)＝f’ ₁ (x) The equation is solved to obtain [ a ] ₀ a ₁ …a _n ]。

Then, the Rx combining of the convergence unit combines signals received from different modules of the RRU to obtain a signal Y _L ＝f ₁ ^m (x)+f ₂ ⁿ (x) + … …. The transmitting end Tx in the aggregation unit transmits the transmitting signal X to the nonlinear model cancellation processing unit, and the output signal is f (X), f (X) and the signal Y _L The subtracted f '(x) is fed back to a nonlinear model cancellation processing unit via a receiving channel, f' (x) =y _L -f (x), the nonlinear model solving the cancellation processing unit continuing to solve f '(x) to obtain f' (x), the receiving channel recycling the f received after L-2 times according to the procedure ^L (x) And sent to the BBU. It should be noted that, in order to make the signals processed by each module in the RRU be processed after being combined, the time delay needs to be aligned in advance between each module.

Illustratively, f (x) =b ₀ *x ⁿ +b ₁ *x ^n-1 +……b _n-1 *x+b _n . By the method of [ b ] ₀ b ₁ …b _n ]*X＝f(x)，[b ₀ b ₁ …b _n ]* The equation of f (x) =f' (x) is solved to obtain [ b0 b1 … … ]]The balance of the above-mentioned components are as follows ₁ (x) Or f ₂ (x) Similarly.

In summary, compared with the method that each module independently performs one-to-one nonlinear cancellation processing, according to the scheme, after each module in the RRU calculates the nonlinear difference part caused by the difference part of the radio frequency device in intermodulation interference, the nonlinear difference part is sent to the convergence unit to perform centralized nonlinear fitting of resource pooling, so that the plurality of modules in the common cell complete the cancellation processing under the cooperation of the convergence unit, the modules and algorithms of the nonlinear model cancellation processing unit deployed by each module can be greatly simplified, the deployment cost is reduced, the resource consumption is reduced, and even under the condition that the number of channels in the distributed base station is continuously increased, the cost is reduced and the resources are saved. Compared with the arrangement of feedback channels among a plurality of radio frequency devices, the scheme does not need to arrange the feedback channels, and further saves processing cost. Compared with the DUP with high isolation, the DUP with high isolation is not required to be arranged in the scheme, the influence on the output function of the module is avoided, the cost is further reduced, and resources are saved.

A further example of the basic principle of intermodulation correction provided in the present application is described below in connection with fig. 6.

The example of the basic principle of intermodulation correction shown in fig. 6 is similar to the example shown in fig. 5, with the difference between fig. 5 and fig. 6 that the example in fig. 6 uses a simplified linear model cancellation processing unit in the various modules of the RRU. In this example, the simplified linear model cancellation processing unit is mainly used to solve the linear difference part, such as flatness, delay jitter, etc., in the IMD generated by different modules caused by the difference of radio frequency devices in different modules. The linear difference parts can be solved by a simplified linear model cancellation processing unit of each module by adopting an initial table making immobilization scheme or a linear iteration scheme, so that signals which can be subjected to nonlinear fitting uniformly by a nonlinear model cancellation processing unit of the convergence unit are obtained, and the signals are sent to the convergence unit. Similar to the example shown in fig. 5, each simplified linear model can be controlled by the convergence unit via the control unit to calculate when the cancellation processing unit starts to calculate several times. In addition to the differences described above, the remaining flow may be described with particular reference to the example of fig. 5.

In summary, compared with the method that each module independently performs one-to-one nonlinear cancellation processing, according to the scheme, after each module in the RRU calculates a linear difference part caused by a difference part of a radio frequency device in intermodulation interference, the linear difference part is sent to a convergence unit to perform centralized nonlinear fitting of resource pooling, so that the plurality of modules in a common cell complete the cancellation processing under the cooperation of the convergence unit, the modules and algorithms of the nonlinear model cancellation processing unit deployed by each module can be greatly simplified, the deployment cost is reduced, the resource consumption is reduced, and even under the condition that the number of channels in a distributed base station is continuously increased, the cost is reduced and the resources are saved. Compared with the arrangement of feedback channels among a plurality of radio frequency devices, the scheme does not need to arrange the feedback channels, and further saves processing cost. Compared with the DUP with high isolation, the DUP with high isolation is not required to be arranged in the scheme, the influence on the output function of the module is avoided, the cost is further reduced, and resources are saved.

It should be noted that, the intermodulation correction scheme provided in the present application may be used in a distributed base station, and may also be used in other architectures that need intermodulation correction, which is not limited in this application.

The method-side embodiment of intermodulation correction of the present application is described in detail above with reference to fig. 1 to 6, and the apparatus-side embodiment of intermodulation correction of the present application will be described in detail below with reference to fig. 7 and 8. It should be understood that the descriptions of apparatus embodiments and the descriptions of method embodiments correspond to each other. Thus, parts not described in detail can be seen in the previous method embodiments.

Fig. 7 is a schematic block diagram of an intermodulation correction apparatus provided in an embodiment of the present application. As shown in fig. 7, the apparatus 1000 may include a convergence unit 1100, a remote radio unit 1200.

It is to be understood that the apparatus 1000 may include means for performing the method of the method 400 of fig. 4. And, each unit in the apparatus 1000 and the other operations and/or functions described above are respectively for implementing the corresponding flow of the method 400 in fig. 4.

In one possible implementation, the aggregation unit 1100 includes a first processing unit, a transmitting end, and a receiving combining unit,

the first processing unit is configured to receive a first correction signal, where the first correction signal is a transmission signal from a transmitting end, or the first correction signal is a signal obtained by subtracting or adding a signal output by the first processing unit and a first intermodulation interference signal output by the receiving and combining unit, where the first intermodulation interference signal is obtained by combining, by the receiving and combining unit, a second intermodulation interference signal received from the remote radio unit 1200, and the second intermodulation interference signals are respectively from different modules of the remote radio unit 1200;

The first processing unit is further configured to output a second correction signal according to the first correction signal, where the second correction signal is obtained by performing nonlinear cancellation on the first correction signal by the first processing unit, and the second correction signal is used to subtract or add the first intermodulation interference signal.

Optionally, the first processing unit is further configured to receive an i-th first correction signal, where the i-th first correction signal is obtained by adding or subtracting an i-1-th first intermodulation interference signal from an i-1-th second correction signal, and i is a positive integer greater than 1;

Optionally, the first processing unit is further configured to send indication information to the remote radio unit 1200, where the indication information is used to indicate processing of the received signal, and the processing includes performing linear cancellation or non-linear cancellation on the received signal to obtain at least 2 second intermodulation interference signals.

In another possible implementation, the remote radio unit 1200 includes at least 2 modules,

the remote radio unit 1200 is configured to receive indication information from the aggregation unit 1100, where the indication information is used to indicate processing of a received signal;

The remote radio unit 1200 is further configured to process at least 2 received signals according to the indication information to obtain at least 2 second intermodulation interference signals, where each second intermodulation interference signal is obtained by processing 1 received signal by each module, where the processing includes linear intermodulation or nonlinear intermodulation, and the at least 2 second intermodulation interference signals may be subjected to nonlinear cancellation by a first processing unit in the aggregation unit 1100;

the remote radio unit 1200 is further configured to transmit at least 2 second intermodulation interference signals to the aggregation unit 1100.

It should also be appreciated that aggregation unit 1100 in apparatus 1000 may be implemented by at least one processor.

It should also be appreciated that aggregation unit 1100 in the apparatus 1000 may be implemented by a processor, microprocessor, integrated circuit, or the like integrated on the chip or system-on-chip.

Fig. 8 is another schematic block diagram of an intermodulation correction apparatus 2000 provided by an embodiment of the present application. As shown in fig. 8, the apparatus 2000 includes a processor 2010, a transceiver 2020, and a memory 2030. Wherein the processor 2010, the transceiver 2020, and the memory 2030 are in communication with each other through an internal connection path, the memory 2030 is for storing instructions, and the processor 2010 is for executing the instructions stored in the memory 2030 to control the transceiver 2020 to transmit signals and/or receive signals.

It should be appreciated that the apparatus 2000 may be configured to perform the various steps and/or processes of the method embodiments described above.

Alternatively, the memory 2030 may include read only memory and random access memory and provide instructions and data to the processor. A portion of the memory may also include non-volatile random access memory. The memory 2030 may be a separate device or may be integrated within the processor 2010. The processor 2010 may be configured to execute instructions stored in the memory 2030 and when the processor 2010 executes the instructions stored in the memory, the processor 2010 is configured to perform the steps and/or processes of the method embodiments corresponding to the convergence unit and/or remote radio unit described above.

The transceiver 2020 may include a transmitter and a receiver, among other things. The transceiver 2020 may further include antennas, the number of which may be one or more. The processor 2010 and memory 2030 may be separate devices integrated on different chips than the transceiver 2020. For example, the processor 2010 and the memory 2030 may be integrated in a baseband chip and the transceiver 2020 may be integrated in a radio frequency chip. The processor 2010 and memory 2030 may also be integrated on the same chip as the transceiver 2020. The present application is not limited in this regard.

The transceiver 2020 may also be a communication interface such as an input/output interface, circuitry, etc. The transceiver 2020 may be integrated in the same chip as the processor 2010 and the memory 2020, e.g., in a baseband chip.

It should be understood that the specific examples in the embodiments of the present application are only for helping those skilled in the art to better understand the technical solutions of the present application, and the above specific implementation may be considered as the best implementation of the present application, and not limit the scope of the embodiments of the present application.

It should also be understood that, in various embodiments of the present application, the sequence numbers of the foregoing processes do not mean the order of execution, and the order of execution of the processes should be determined by the functions and internal logic thereof, and should not constitute any limitation on the implementation process of the embodiments of the present application.

It should be understood that, in the above embodiments, only the flow of the dynamic intermodulation correction method provided in the present application is illustrated, and the protection scope of the present application is not limited in any way.

It is also to be understood that in the various embodiments of the application, terms and/or descriptions of the various embodiments may be consistent and may refer to each other in the absence of specific illustrations and logic conflicts with each other, and the technical features of the various embodiments may be combined to form new embodiments in accordance with their inherent logic relationships.

It should be appreciated that in embodiments of the present application, the processor may be a central processing unit (central processing unit, CPU), the processor may also be other general purpose processor, digital signal processor (digital signal processor, DSP), application specific integrated circuit (application specific integrated circuit, ASIC), off-the-shelf programmable gate array (field programmable gate array, FPGA) or other programmable logic device, transistor logic device, hardware components, or any combination thereof. The general purpose processor may be a microprocessor, but in the alternative, it may be any conventional processor or the like.

It should also be appreciated that the memory in embodiments of the present application may be either volatile memory or nonvolatile memory, or may include both volatile and nonvolatile memory. The nonvolatile memory may be a read-only memory (ROM), a Programmable ROM (PROM), an Erasable PROM (EPROM), an electrically Erasable EPROM (EEPROM), or a flash memory. The volatile memory may be random access memory (random access memory, RAM) which acts as an external cache. By way of example, and not limitation, many forms of RAM are available, such as Static RAM (SRAM), dynamic Random Access Memory (DRAM), synchronous Dynamic Random Access Memory (SDRAM), double data rate synchronous dynamic random access memory (DDR SDRAM), enhanced SDRAM (ESDRAM), synchronous Link DRAM (SLDRAM), and direct memory bus RAM (DR RAM). It should be noted that the memory of the systems and methods described herein is intended to comprise, without being limited to, these and any other suitable types of memory.

The method steps in the embodiments of the present application may be implemented by hardware, or may be implemented by a processor executing software instructions. The software instructions may be comprised of corresponding software modules that may be stored in random access memory, flash memory, read only memory, programmable read only memory, erasable programmable read only memory, electrically erasable programmable read only memory, registers, hard disk, removable disk, CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor such the processor can read information from, and write information to, the storage medium.

Those of ordinary skill in the art will appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, or combinations of computer software and electronic hardware. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the solution. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present application.

It will be clear to those skilled in the art that, for convenience and brevity of description, specific working procedures of the above-described systems, apparatuses and units may refer to corresponding procedures in the foregoing method embodiments, and are not repeated herein.

In the several embodiments provided in this application, it should be understood that the disclosed systems, devices, and methods may be implemented in other manners. For example, the apparatus embodiments described above are merely illustrative, e.g., the division of the units is merely a logical function division, and there may be additional divisions when actually implemented, e.g., multiple units or components may be combined or integrated into another system, or some features may be omitted or not performed. Alternatively, the coupling or direct coupling or communication connection shown or discussed with each other may be an indirect coupling or communication connection via some interfaces, devices or units, which may be in electrical, mechanical or other form.

The units described as separate units may or may not be physically separate, and units shown as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the technical scheme of the embodiment of the application.

In addition, each functional unit in each embodiment of the present application may be integrated in one processing unit, or each unit may exist alone physically, or two or more units may be integrated in one unit.

The functions, if implemented in the form of software functional units and sold or used as a stand-alone product, may be stored in a computer-readable storage medium. Based on such understanding, the technical solution of the present application may be embodied essentially or in a part contributing to the prior art or in a part of the technical solution, in the form of a software product stored in a storage medium, including several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the methods described in the embodiments of the present application. And the aforementioned storage medium includes: a usb disk, a removable hard disk, a ROM, a RAM, a magnetic disk, or an optical disk, etc.

The foregoing is merely specific embodiments of the present application, but the scope of the present application is not limited thereto, and any person skilled in the art can easily think about changes or substitutions within the technical scope of the present application, and the changes and substitutions are intended to be covered by the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. The intermodulation correction method is applied to a distributed base station, and is characterized in that the distributed base station comprises a convergence unit and a remote radio unit, the convergence unit comprises a first processing unit, a transmitting end and a receiving and combining unit, and the method comprises the following steps:

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

3. A method according to claim 1 or 2, characterized in that,

the first processing unit sends indication information to the remote radio unit, wherein the indication information is used for indicating processing of a received signal, and the processing comprises linear cancellation or nonlinear cancellation of the received signal to obtain the second intermodulation interference signal.

4. A method of intermodulation correction applied to a distributed base station, wherein the distributed base station comprises a convergence unit and a remote radio unit, the remote radio unit comprising at least 2 modules, the method comprising:

5. The intermodulation correction device is characterized by comprising a converging unit and a remote radio unit, wherein the converging unit comprises a first processing unit, a transmitting end and a receiving combining unit,

6. The method of claim 5, wherein the step of determining the position of the probe is performed,

the first processing unit is further configured to receive an ith first correction signal, where the ith first correction signal is obtained by adding or subtracting an ith-1 th second correction signal from an ith-1 th first intermodulation interference signal, and i is a positive integer greater than 1;

7. The method according to claim 5 or 6, wherein,

the first processing unit is further configured to send indication information to the remote radio unit, where the indication information is used to indicate processing of a received signal, and the processing includes performing linear cancellation or nonlinear cancellation on the received signal to obtain the at least 2 second intermodulation interference signals.

8. An intermodulation correction apparatus, comprising a convergence unit and a remote radio unit, wherein the remote radio unit comprises at least 2 modules,

9. A communication system, characterized in that it comprises an apparatus according to any of claims 5 to 8.

10. A distributed base station, comprising: the apparatus of any of claims 5 to 8 and a baseband unit.

11. An optical communication apparatus, comprising: a processor and a communication interface through which the processor is coupled with a memory, the processor being for executing program code in the memory to implement the method of any one of claims 1 to 4.

12. A chip comprising programmable logic circuits and/or program instructions for implementing the method of any one of claims 1 to 4 when the chip is run.

13. A computer-readable storage medium, comprising: the computer readable storage medium stores a computer program which, when run on the computer, causes the computer to perform the method of any one of claims 1 to 4.

14. A computer program, characterized in that the computer program, when executed on a computer, causes the computer to perform the method according to any of claims 1 to 4.