WO2021132928A1

WO2021132928A1 - Signal processing apparatus, remote radio apparatus, and base station

Info

Publication number: WO2021132928A1
Application number: PCT/KR2020/017587
Authority: WO
Inventors: Meiling Zhang; Shaomin ZHANG; Jia Yan
Original assignee: Samsung Electronics Co., Ltd.
Priority date: 2019-12-25
Filing date: 2020-12-04
Publication date: 2021-07-01
Also published as: CN111082829B; CN111082829A

Abstract

The present disclosure discloses a signal processing apparatus, a remote radio apparatus, and a base station. The signal processing apparatus includes cascaded first crest factor reduction module (CFR1) and first pre-distortion module (PD1), in which the first crest factor reduction module (CFR1) outputs a first crest factor reduction signal (y1) to the first pre-distortion module (PD1), and the first pre-distortion module (PD1) outputs a first pre-distortion signal (x1); and a second pre-distortion module (PD2) with an output end coupled to an input end of the first crest factor reduction module (CFR1), to output a second pre-distortion signal (x2) to the first crest factor reduction module (CFR1).

Description

SIGNAL PROCESSING APPARATUS, REMOTE RADIO APPARATUS, AND BASE STATION

The present disclosure relates to the communication technical field, and especially to a single processing apparatus, a remote radio apparatus, and a base station.

To meet the demand for wireless data traffic having increased since deployment of 4G communication systems, efforts have been made to develop an improved 5G or pre-5G communication system. Therefore, the 5G or pre-5G communication system is also called a 'Beyond 4G Network' or a 'Post LTE System'. The 5G communication system is considered to be implemented in higher frequency (mmWave) bands, e.g., 60GHz bands, so as to accomplish higher data rates. To decrease propagation loss of the radio waves and increase the transmission distance, the beamforming, massive multiple-input multiple-output (MIMO), Full Dimensional MIMO (FD-MIMO), array antenna, an analog beam forming, large scale antenna techniques are discussed in 5G communication systems. In addition, in 5G communication systems, development for system network improvement is under way based on advanced small cells, cloud Radio Access Networks (RANs), ultra-dense networks, device-to-device (D2D) communication, wireless backhaul, moving network, cooperative communication, Coordinated Multi-Points (CoMP), reception-end interference cancellation and the like. In the 5G system, Hybrid FSK and QAM Modulation (FQAM) and sliding window superposition coding (SWSC) as an advanced coding modulation (ACM), and filter bank multi carrier (FBMC), non-orthogonal multiple access(NOMA), and sparse code multiple access (SCMA) as an advanced access technology have been developed.

The Internet, which is a human centered connectivity network where humans generate and consume information, is now evolving to the Internet of Things (IoT) where distributed entities, such as things, exchange and process information without human intervention. The Internet of Everything (IoE), which is a combination of the IoT technology and the Big Data processing technology through connection with a cloud server, has emerged. As technology elements, such as "sensing technology", "wired/wireless communication and network infrastructure", "service interface technology", and "Security technology" have been demanded for IoT implementation, a sensor network, a Machine-to-Machine (M2M) communication, Machine Type Communication (MTC), and so forth have been recently researched. Such an IoT environment may provide intelligent Internet technology services that create a new value to human life by collecting and analyzing data generated among connected things. IoT may be applied to a variety of fields including smart home, smart building, smart city, smart car or connected cars, smart grid, health care, smart appliances and advanced medical services through convergence and combination between existing Information Technology (IT) and various industrial applications.

In line with this, various attempts have been made to apply 5G communication systems to IoT networks. For example, technologies such as a sensor network, Machine Type Communication (MTC), and Machine-to-Machine (M2M) communication may be implemented by beamforming, MIMO, and array antennas. Application of a cloud Radio Access Network (RAN) as the above-described Big Data processing technology may also be considered to be as an example of convergence between the 5G technology and the IoT technology.

In data transmission scenarios such as at a base station, a communication device needs to perform pre-distortion processing and crest factor reduction processing for signals.

For a common non-linear processing manner in the communication device, usually the pre-distortion processing is after the crest factor reduction processing. A structure corresponding to this non-linear processing manner is not flexible enough.

According to an aspect of the present disclosure, a signal processing apparatus is provided, including: cascaded first crest factor reduction module and first pre-distortion module, wherein the first crest factor reduction module outputs a first crest factor reduction signal to the first pre-distortion module, and the first pre-distortion module outputs a first pre-distortion signal; and a second pre-distortion module with an output end coupled to an input end of the first crest factor reduction module to output a second pre-distortion signal to the first crest factor reduction module.

In some embodiment, the signal processing apparatus further includes a power amplifier with an input end coupled to an output end of the first pre-distortion module, to output a power amplified signal.

In some embodiments, the signal processing apparatus further includes: a second crest factor reduction module with an input end used to receive a baseband signal and an output end coupled to the second pre-distortion module, to output a second crest factor reduction signal to the second pre-distortion module.

In some embodiments, the signal processing apparatus further includes: a signal processing module with an input end coupled to an output end of the power amplifier, to output a feedback signal, in which the feedback signal is a ratio of the power amplified signal to a gain of the power amplifier; a second post-inverse processing module to receive the feedback signal, perform inverse pre-distortion processing for the feedback signal, and output a second inversely processed signal; a second adder to output a second signal, in which the second signal is a difference between the second inversely processed signal and the first crest factor reduction signal; and a second trainer to train a coefficient of the second pre-distortion module based on the second signal to obtain a second training result, and output the second training result to the second pre-distortion module and the second post-inverse processing module.

In some embodiments, the signal processing apparatus further includes: a first post-inverse processing module to receive the second inversely processed signal, and perform inverse pre-distortion processing for the second inversely processed signal to obtain a first inversely processed signal; a first adder to output a first signal, in which the first signal is a difference between the first inversely processed signal and the first pre-distortion signal; and a first trainer to train a coefficient of the first post-inverse processing module based on the first signal to obtain a first training result, and output the first training result to the first post-inverse processing module.

In some embodiment, the first post-inverse processing module is also configured to output the first training result to the first pre-distortion module.

In some embodiments, the first pre-distortion module and the second pre-distortion module are set to different operating frequencies.

In some embodiments, the first pre-distortion module and the second pre-distortion module are set to be different pre-distortion models.

In some embodiments, the second pre-distortion module performs a first pre-distortion operation, and the first pre-distortion module performs a second pre-distortion operation.

An aspect of the present disclosure provides a remote radio apparatus, including the signal processing apparatus according to the embodiments of the present disclosure.

An aspect of the present disclosure provides a base station, including: a baseband; the remote radio apparatus; and an antenna.

In summary, the signal processing apparatus according to the embodiments of the present disclosure may cascade a first crest factor reduction module CFR1 and a first pre-distortion module PD1 with a second pre-distortion module PD2, so that the first crest factor reduction module CFR1 is located between the first pre-distortion module PD1 and the second pre-distortion module PD2. Herein, the signal processing apparatus may perform PD processing for a signal through two stages of pre-distortion modules (i.e., the PD1 and the PD2). In this way, in the signal processing apparatus according to the embodiments of the present disclosure, the number of the pre-distortion modules and the locations of the pre-distortion modules relative to the crest factor reduction modules may be flexibly set according to actual signal processing requirements, so as to flexibly perform non-linear processing for the signal. In addition, in the signal processing apparatus of the present disclosure, an operating frequency and a model of each pre-distortion module may be configured as demanded, so as to implement the signal processing apparatus in scenarios having different pre-distortion requirements, which increases the implementation scope of the signal processing apparatus.

In order to more clearly illustrate the technical schemes in the embodiments of the present disclosure, the accompanying drawings required to be used in the description of the embodiments will be briefly described below. Apparently, the drawings in the description below are some embodiments of the present disclosure, and a person of ordinary skill in the art would obtain other drawings from these drawings provided herein without involving any inventive effort.

FIG.1 shows a schematic diagram of a signal processing apparatus according to some embodiments of the present disclosure;

FIG.2 shows a schematic diagram of a signal processing apparatus according to some embodiments of the present disclosure;

FIG.3 shows a schematic diagram of a signal processing apparatus according to some embodiments of the present disclosure;

FIG.4 shows a schematic diagram of a remote radio apparatus according to some embodiments of the present disclosure; and

FIG.5 shows a schematic diagram of a base station according to some embodiments of the present disclosure.

In the following, the technical solutions in the embodiments of the present disclosure will be clearly and fully described with reference to the drawings in the embodiments of the present disclosure. Apparently, the embodiments described herein are only a part of embodiments of the present disclosure, rather than all the embodiments. Based on the embodiments in the present disclosure, other embodiments obtained by a person of ordinary skill in the art without creative efforts shall fall within the protection scope of the present disclosure.

In some implementation scenarios, a remote radio unit (RRU) may use a pre-distortion (PD) module to perform pre-distortion processing for a signal, and may use a crest factor reduction (CFR) module to perform crest factor reduction processing for a signal. An RRU usually adopts one crest factor reduction module and one pre-distortion module, and processing of the crest factor reduction module is before that of the pre-distortion module.

Fig.1 shows a schematic diagram of a signal processing apparatus according to some embodiments of the present disclosure. The signal processing apparatus in Fig.1 for example may be used in a remote radio apparatus (i.e., an RRU), but not limited thereto.

As shown in Fig.1, the signal processing apparatus 10 may include a second pre-distortion module PD2. The signal processing apparatus 10 may include cascaded first crest factor reduction module CFR1 and a first pre-distortion module PD1. The first crest factor reduction module CFR1 outputs a first crest factor reduction signal y1 to the first pre-distortion module PD1, and the first pre-distortion module PD1 outputs a first pre-distortion signal x1.

In addition, the signal processing apparatus 10 may include the second pre-distortion module PD2. The second pre-distortion module PD2 for example may receive a baseband signal BB. An output end of the second pre-distortion module PD2 is coupled to an input end of the first crest factor reduction module CFR1, and the second pre-distortion module PD2 outputs a second PD signal x2 to the first crest factor reduction module CFR1. It is to be specified that the first crest factor reduction module CRF1 is located between the first pre-distortion module PD1 and the second pre-distortion module PD2 so that the two separated stages of pre-distortion processing may be performed respectively through the first pre-distortion module PD1 and the second pre-distortion module PD2.

In summary, the signal processing apparatus according to the embodiments of the present disclosure may cascade the first crest factor reduction module CFR1 and the first pre-distortion module PD1 with the second pre-distortion module PD2, so that the first crest factor reduction module CFR1 is located between the first pre-distortion module PD1 and the second pre-distortion module PD2. Herein, the signal processing apparatus may perform PD processing for a signal through two stages of pre-distortion modules (i.e., the PD1 and the PD2). In this way, in the signal processing apparatus according to the embodiments of the present disclosure, the number of the pre-distortion modules and the locations of the pre-distortion modules relative to the crest factor reduction module may be flexibly set according to actual signal processing requirements, so as to flexibly perform non-linear processing for a signal. In addition, in the signal processing apparatus of the present disclosure, an operating frequency and a model of each pre-distortion module may be configured as demanded, so as to implement the signal processing apparatus in scenarios having different pre-distortion requirements, which increases the implementation scope of the signal processing apparatus. For example, the operating frequencies and the models of respective pre-distortion modules may be the same. As another example, the operating frequencies of multiple pre-distortion modules may be different, or the models of them may be different, or both the operating frequencies and the models of them may be different.

In addition, the signal processing apparatus performs the PD processing for a signal through two stages of pre-distortion modules. For example, the second pre-distortion module PD2 performs a first PD operation, and the first pre-distortion module PD1 performs a second PD operation. In this way, the signal processing apparatus may improve linear correction performance for the signal. For example, in scenarios such as a broadband scenario, a multicarrier scenario, and a large power scenario, the signal processing apparatus of the present disclosure can meet linear correction requirements for signals.

In some embodiments, the signal processing apparatus further includes a power amplifier (PA) with an input end coupled to an output end of the first pre-distortion module PD1. The PA may output a power amplified signal s1.

Fig.2 shows a schematic diagram of a signal processing apparatus according to some embodiments of the present disclosure. Based on Fig.1, the signal processing apparatus in Fig.2 further includes a second crest factor reduction module CFR2. An input end of the second crest factor reduction module CFR2 may receive a baseband signal BB. An output end of the second crest factor reduction module CFR2 is coupled to the second pre-distortion module PD2, and outputs a second CFR signal y2 to the second pre-distortion module PD2.

In summary, the signal processing apparatus may perform crest factor reduction processing for a signal through the first crest factor reduction module CFR1 and the second crest factor reduction module CFR2. For example, the second crest factor reduction module CFR2 may perform first CFR processing, and the first crest factor reduction module CFR 1 may perform second CFR processing. Herein, through the second crest factor reduction module CFR2, the signal processing apparatus can reduce performance requirements for the first crest factor reduction module CFR 1. Additionally, a frequency and power consumption of the second crest factor reduction module CFR 2 may be configured as demanded, thus improving the flexibility of crest factor reduction. In the signal processing apparatus of the present disclosure, the numbers and locations of the crest factor reduction modules (e.g., the CFR1 and the CFR2) and the pre-distortion modules (e.g., the PD1 and the PD2) may be flexibly configured, thus improving the flexibility of linear correction. In addition, it is to be specified that the number of the crest factor reduction modules and the number of the pre-distortion modules are not limited to the numbers as shown in Fig.2, more crest factor reduction modules and pre-distortion modules may be added as demanded. For example, the CFR1 and the CFR2 may be set between the PD1 and the PD2, or before the PD1 and the PD2, but not limited thereto.

Fig.3 shows a schematic diagram of a signal processing apparatus according to some embodiments of the present disclosure. Based on Fig.2, the signal processing apparatus in Fig.3 further includes modules related to training the coefficient of the first pre-distortion module PD1 and the coefficient of the second pre-distortion module PD2.

As shown in Fig.3, the signal processing apparatus 10 may further include a signal processing module D1, a second post-inverse processing module P2 (also referred to as Post-inverse 2), a second adder A2, a second trainer L2 (also referred to as Learning 2), a first post-inverse processing module P1 (also referred to as Post-inverse1), a first adder A1, and a first trainer L1 (also referred to as Learning1).

An input end of the signal processing module D1 is coupled to an output end of the PA, to output a feedback signal z. The feedback signal z is a ratio of the power amplified signal s1 to a gain of the PA. For example, the gain of the PA is G, where z/s1=1/G.

The second post-inverse processing module P2 is configured to receive the feedback signal z, and perform inverse PD processing for the feedback signal z to output a second inversely processed signal z2.

The second adder A2 is configured to output a second signal e2. The second signal e2 is a difference between the second inversely processed signal z2 and the first CFR signal y1, i.e., e2=z2-y1.

The second trainer L2 is configured to train a coefficient of the second pre-distortion module PD2 based on the second signal e2 to obtain a second training result, and output the second training result to the second pre-distortion module PD2 and the second post-inverse processing module P2. Herein, the second pre-distortion module PD2 may carry out various PD processing algorithms as demanded. Herein the coefficient of the second pre-distortion module PD2 is a coefficient dependent on a PD processing algorithm. The second trainer L2 trains the coefficient of the second pre-distortion module PD2 to reduce a subsequent second signal (i.e., reducing a difference between z2 and y1), so as to improve the accuracy of PD processing of the second pre-distortion module PD2.

The first post-inverse processing module P1 is configured to receive the second inversely processed signal z2, and perform inverse PD processing for the second inversely processed signal z2 to obtain a first inversely processed signal z1.

The first adder A1 is configured to output a first signal e1. The first signal e1 is a difference between the first inversely processed signal z1 and the first PD signal x1, i.e., e1=z1-x1.

The first trainer L1 is configured to train a coefficient of the first post-inverse processing module P1 based on the first signal e1 to obtain a first training result, and output the first training result to the first post-inverse processing module P1. The coefficient of the first post-inverse processing module P1 is a coefficient of a PD algorithm implemented by the first post-inverse processing module P1. In addition, the first post-inverse processing module P1 may output the first training result to the first pre-distortion module PD1. In this way, the first pre-distortion module PD1 may use the first training result as the coefficient of the first pre-distortion module PD1. The coefficient of the first pre-distortion module PD1 is a coefficient of a PD algorithm implemented by the first pre-distortion module PD1.

In summary, the first trainer L1 may reduce e1 (i.e., the difference between z1 and x1) through an indirect training method (i.e., using the training result of the P1 as the newest factor of the PD1), thus improving the accuracy of PD processing of the first pre-distortion module PD1.

Fig.4 shows a schematic diagram of a remote radio apparatus according to some embodiments of the present disclosure. As shown in Fig.4, the remote radio apparatus may also be referred to as RRU, and may include the signal processing apparatus 10 shown in Fig.2.

Fig.5 shows a schematic diagram of a base station according to some embodiments of the present disclosure. As shown in Fig.5, a base station 100 may include a baseband 30, a remote radio apparatus 20, and an antenna 40. The baseband 30 may provide a baseband signal BB to the remote radio apparatus 20. The remote radio apparatus 20 may generate a radio signal to be transmitted according to the baseband signal. The antenna 40 may beam away the radio signal.

The foregoing is only exemplary embodiments of the present disclosure and is not intended to limit the present disclosure. Any modification, equivalent substitution, and improvement without departing from the spirit and principle of the present disclosure should be covered in the protection scope of the present disclosure.

Various embodiments of the present application can be used for wireless communication.

Claims

A signal processing apparatus, characterized by comprising:

cascaded first crest factor reduction module (CFR1) and first pre-distortion module (PD1), wherein the first crest factor reduction module (CFR1) outputs a first crest factor reduction signal (y1) to the first pre-distortion module (PD1), and the first pre-distortion module (PD1) outputs a first pre-distortion signal (x1); and

a second pre-distortion module (PD2) with an output end coupled to an input end of the first crest factor reduction module (CFR1) to output a second pre-distortion signal (x2) to the first crest factor reduction module (CFR1).
The signal processing apparatus of claim 1, characterized in that the apparatus further comprises:

a power amplifier (PA) with an input end coupled to an output end of the first pre-distortion module (PD1), to output a power amplified signal (s1).
The signal processing apparatus of claim 1, characterized in that the apparatus further comprises:

a second crest factor reduction module (CFR2) with an input end used to receive a baseband signal (BB) and an output end coupled to the second pre-distortion module (PD2), to output a second crest factor reduction signal (y2) to the second pre-distortion module (PD2).
The signal processing apparatus of claim 2, characterized in that the apparatus further comprises:

a signal processing module (D1) with an input end coupled to an output end of the power amplifier (PA), to output a feedback signal (z), wherein the feedback signal (z) is a ratio of the power amplified signal (s1) to a gain (G) of the power amplifier;

a second post-inverse processing module (P2) to receive the feedback signal (z), perform inverse pre-distortion processing for the feedback signal (z), and output a second inversely processed signal (z2);

a second adder (A2) to output a second signal (e2), wherein the second signal (e2) is a difference between the second inversely processed signal (z2) and the first crest factor reduction signal (y1); and

a second trainer (L2) to train a coefficient of the second pre-distortion module (PD2) based on the second signal (e2) to obtain a second training result, and output the second training result to the second pre-distortion module (PD2) and the second post-inverse processing module (P2).
The signal processing apparatus of claim 4, characterized in that the apparatus further comprises:

a first post-inverse processing module (P1) to receive the second inversely processed signal (z2), and perform inverse pre-distortion processing for the second inversely processed signal (z2) to obtain a first inversely processed signal (z1);

a first adder (A1) to output a first signal (e1), wherein the first signal (e1) is a difference between the first inversely processed signal (z1) and the first pre-distortion signal (x1); and

a first trainer (L1) to train a coefficient of the first post-inverse processing module (P1) based on the first signal (e1) to obtain a first training result, and output the first training result to the first post-inverse processing module (P1).
The signal processing apparatus of claim 5, characterized in that the first post-inverse processing module (P1) is also configured to output the first training result to the first pre-distortion module (PD1).
The signal processing apparatus of claim 1, characterized in that the first pre-distortion module (PD1) and the second pre-distortion module (PD2) are set to different operating frequencies.
The signal processing apparatus of claim 1, characterized in that the first pre-distortion module (PD1) and the second pre-distortion module (PD2) are set to be different pre-distortion models.
A remote radio apparatus, characterized by comprising the signal processing apparatus,

wherein the signal processing apparatus comprises:

cascaded first crest factor reduction module (CFR1) and first pre-distortion module (PD1), wherein the first crest factor reduction module (CFR1) outputs a first crest factor reduction signal (y1) to the first pre-distortion module (PD1), and the first pre-distortion module (PD1) outputs a first pre-distortion signal (x1); and

a second pre-distortion module (PD2) with an output end coupled to an input end of the first crest factor reduction module (CFR1) to output a second pre-distortion signal (x2) to the first crest factor reduction module (CFR1).
The remote radio apparatus of claim 9, characterized in that the signal processing apparatus further comprises:

a power amplifier (PA) with an input end coupled to an output end of the first pre-distortion module (PD1), to output a power amplified signal (s1);

a signal processing module (D1) with an input end coupled to an output end of the power amplifier (PA), to output a feedback signal (z), wherein the feedback signal (z) is a ratio of the power amplified signal (s1) to a gain (G) of the power amplifier;

a second post-inverse processing module (P2) to receive the feedback signal (z), perform inverse pre-distortion processing for the feedback signal (z), and output a second inversely processed signal (z2);

a second adder (A2) to output a second signal (e2), wherein the second signal (e2) is a difference between the second inversely processed signal (z2) and the first crest factor reduction signal (y1); and

a second trainer (L2) to train a coefficient of the second pre-distortion module (PD2) based on the second signal (e2) to obtain a second training result, and output the second training result to the second pre-distortion module (PD2) and the second post-inverse processing module (P2).
The remote radio apparatus of claim 10, characterized in that the signal processing apparatus further comprises:

a first post-inverse processing module (P1) to receive the second inversely processed signal (z2), and perform inverse pre-distortion processing for the second inversely processed signal (z2) to obtain a first inversely processed signal (z1);

a first adder (A1) to output a first signal (e1), wherein the first signal (e1) is a difference between the first inversely processed signal (z1) and the first pre-distortion signal (x1); and

a first trainer (L1) to train a coefficient of the first post-inverse processing module (P1) based on the first signal (e1) to obtain a first training result, and output the first training result to the first post-inverse processing module (P1).
The remote radio apparatus of claim 11, characterized in that the first post-inverse processing module (P1) is also configured to output the first training result to the first pre-distortion module (PD1).
A base station, characterized by comprising: a baseband; a remote radio apparatus with a signal processing apparatus; and an antenna,

wherein the signal processing apparatus comprises:

cascaded first crest factor reduction module (CFR1) and first pre-distortion module (PD1), wherein the first crest factor reduction module (CFR1) outputs a first crest factor reduction signal (y1) to the first pre-distortion module (PD1), and the first pre-distortion module (PD1) outputs a first pre-distortion signal (x1); and

a second pre-distortion module (PD2) with an output end coupled to an input end of the first crest factor reduction module (CFR1) to output a second pre-distortion signal (x2) to the first crest factor reduction module (CFR1).
The base station of claim 13, characterized in that the signal processing apparatus further comprises:

a power amplifier (PA) with an input end coupled to an output end of the first pre-distortion module (PD1), to output a power amplified signal (s1);

a signal processing module (D1) with an input end coupled to an output end of the power amplifier (PA), to output a feedback signal (z), wherein the feedback signal (z) is a ratio of the power amplified signal (s1) to a gain (G) of the power amplifier;

a second post-inverse processing module (P2) to receive the feedback signal (z), perform inverse pre-distortion processing for the feedback signal (z), and output a second inversely processed signal (z2);

a second adder (A2) to output a second signal (e2), wherein the second signal (e2) is a difference between the second inversely processed signal (z2) and the first crest factor reduction signal (y1); and

a second trainer (L2) to train a coefficient of the second pre-distortion module (PD2) based on the second signal (e2) to obtain a second training result, and output the second training result to the second pre-distortion module (PD2) and the second post-inverse processing module (P2).
The base station of claim 14, characterized in that the signal processing apparatus further comprises:

a first post-inverse processing module (P1) to receive the second inversely processed signal (z2), and perform inverse pre-distortion processing for the second inversely processed signal (z2) to obtain a first inversely processed signal (z1);

a first adder (A1) to output a first signal (e1), wherein the first signal (e1) is a difference between the first inversely processed signal (z1) and the first pre-distortion signal (x1); and

a first trainer (L1) to train a coefficient of the first post-inverse processing module (P1) based on the first signal (e1) to obtain a first training result, and output the first training result to the first post-inverse processing module (P1).