Wireless communication device, wireless communication system, and wireless communication method

Abstract

To autonomously determine execution and stop of interrupt of a stabilization signal and avoid interference due to the radiation of the stabilization signal.SOLUTION: A determination unit (11) detects the presence / absence of a transmission signal for each transmission symbol for each of a plurality of transmitters (13). The determination unit (11), when detecting that there is the transmission signal in the arbitrary transmitter (13) in the plurality of transmitters (13), and detecting that there is no transmission signal in all of the transmitters (13) with a transmission symbol before a transmission symbol of transmission of the transmission signal by the arbitrary transmitter (13), makes the stabilization signal for stabilizing the characteristic of an arbitrary transmission amplifier (14) corresponding to the arbitrary transmitter (13) cut into a time area before a time area of the transmission signal to make the stabilization signal pass through the arbitrary transmitter (13) and the arbitrary transmission amplifier (14) before the transmission signal passes through the arbitrary transmitter (13) and the arbitrary transmission amplifier (14).SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present disclosure relates to a wireless communication device, a wireless communication system, and a wireless communication method.

Background Art

[0002] Compared with GaAs (Gallium Arsenide), GaN (Gallium Nitride) has advantages in that it has a large bandgap energy, enables high breakdown voltage and miniaturization, and has a high electron mobility. Therefore, in wireless communication devices such as wide-area base stations, macro base stations, and AAS (Active Antenna System), an AMP (hereinafter, appropriately referred to as "GaN AMP") using a GaN FET (Field Effect Transistor) and a GaN HEMT (High Electron Mobility Transistor) or a GaN 2DEG FET (Two-Dimensional Electron Gas FET) is often adopted as a transmission AMP.

[0003] However, when the transmission AMP, which is a GaN AMP, operates at a large amplitude and high power, measures need to be taken for various parasitic phenomena. Among these parasitic phenomena, for example, a phenomenon called current collapse is a phenomenon in which the drain current decreases as the drain voltage is applied. Regarding current collapse, for example, it is described in Patent Document 1.

[0004] Furthermore, in GaN amplifiers used for transmitting, transient phenomena such as drain lag and gate lag also pose problems. In Class C and above transmitting amplifiers, Class C amplification begins when drain current flows in response to a certain amplitude of the transmitted signal, and the basic amplified signal is output by a matching circuit that matches the output of the transmitting amplifier. Drain lag is a phenomenon in which, when the drain voltage is abruptly switched from Off to On to enable amplification of the transmitting amplifier, the drain current changes transiently and slowly until it reaches a steady voltage state. In addition, when a wireless communication device equipped with a transmitting amplifier operates in TDD (Time Division Duplex) mode, the transmitting amplifier is turned Off / On in accordance with the switching between UL (Up Link) and DL (Down Link). During the On / Off startup of a transmitting amplifier, a rapid On / Off control is performed, instantaneously changing the gate voltage from a pinch-off state (where the gate voltage is set deep relative to the electron transfer channel below the gate, expanding the depletion layer and closing the electron transfer channel between the drain and source; this state is called pinch-off, and this gate voltage value is called the pinch-off voltage) to a gate voltage that allows the desired drain current to flow. Gate lag is a phenomenon in which, in response to this rapid control of the gate voltage, the drain current changes transiently and slowly until it reaches a steady voltage state. These gate lag and drain lag (hereinafter referred to as "Gate / Drain Lag" as appropriate) can lead to transient response delay failures when a GaN transmitting amplifier performs high-speed On / Off and burst operations to achieve TDD operation. A normal state means that nonlinear distortion characteristics such as gain, output, and AM (Amplitude Modulation)-AM / AM-PM (Phase Modulation) are in a steady state. In this context, LTE (Long Term Evolution) and 5G (Fifth Generation) base stations, under TDD (Technical Deposition Device) systems, perform low-power adaptive control by using burst operation to turn the transmitting AMP on and off over time, or by frequently turning the transmitting AMP on and off in response to the transmitting symbol.In that case, due to the transient response delay mentioned above, it was necessary to significantly advance the On control of the transmitting amplifier, which meant that it took a lot of time to stabilize the transmitted signal.

[0005] Furthermore, in a GaN AMP (transmitting amplifier), when transient phenomena such as the aforementioned gate / drain lag occur, deep and surface charge state changes occur on the GaN FET's substrate. This state traps moving electrons within the channel, causing charge and discharge, and the charge and discharge time has a certain time constant. As a result, before the transmission signal is input to the transmitting amplifier, the time it takes for the drain current to reach the target steady-state drain current is significantly delayed due to the Off / On operation of the transmitting amplifier. Consequently, when the transmitting signal passes through the transmitting amplifier, the gain, output, and nonlinear distortion characteristics of the initial part of the transmitted signal do not reach a normal state. This means that, in the low-power adaptive control described above, the stable characteristics of the transmitting amplifier cannot be ensured each time the transmitting amplifier is turned on.

[0006] Consequently, if LTE or 5G base stations employ GaN AMPs for transmission, it becomes difficult to perform the aforementioned low-power adaptive control under a TDD system, resulting in numerous malfunctions affecting the system characteristics of the TDD system.

[0007] In the case of wireless communication devices equipped with a transmitting amplifier that has a poor Gate / Drain Lag (GaN AMP), it has been found that an overshoot occurs in the EVM (Error Vector Magnitude) of the leading symbol in the transmitted signal immediately after the transmitting amplifier is turned on, and that this EVM overshoot causes numerous malfunctions. Therefore, it is necessary to suppress the EVM overshoot of the leading symbol in the transmitted signal to avoid malfunctions caused by this overshoot.

[0008] One possible method to achieve this is to insert an AMP stabilization signal with the widest possible bandwidth into the time domain preceding the time domain of the transmitted signal, so that the AMP stabilization signal passes through the transmitting AMP before the transmitted signal passes through the transmitting AMP.

[0009] In other words, by inputting an AMP stabilization signal to the transmitting AMP before the initial symbol of the transmitted signal is input to the transmitting AMP, the current collapse and gate / drain lag of the transmitting AMP are resolved early. This allows characteristic variations caused by the current collapse and gate / drain lag of the transmitting AMP to converge early, and the nonlinear distortion characteristics such as the gain, output, and AM-AM / AM-PM of the transmitting AMP can be stabilized. As a result, many problems caused by EVM overshoot of the initial symbol of the transmitted signal are avoided, and signal quality is guaranteed from the initial symbol of the transmitted signal and any initial symbol in the transmitting slot. Furthermore, since the AM-AM / AM-PM characteristics of the transmitting AMP in the initial symbol section of the transmitted signal are already stable when the initial symbol of the transmitted signal is input to the transmitting AMP, the initial symbol of the transmitted signal and subsequent symbols are stably distortion-compensated by the DPD (Digital Pre-Distortion) in the transmitter (TX). This also contributes to the guarantee of signal quality from the initial symbol of the DL signal. The TX is located within the TRX, which is a transceiver. [Prior art documents] [Patent Documents]

[0010] [Patent Document 1] Japanese Patent Publication No. 2012-227795 [Non-patent literature]

[0011] [Non-Patent Document 1] ECC Recommendation (15)01, “Cross-border coordination for Mobile / Fixed Communications Networks (MFCN) in the frequency bands: 694-790 MHz, 1427-1518 MHz and 3400-3800 MHz”, Approved 13 February 2015, latest amendment on 14 February 2020. [Overview of the project] [Problems that the invention aims to solve]

[0012] As mentioned above, in wireless communication devices equipped with a transmitting amplifier that is a GaN AMP with poor Gate / Drain Lag, malfunctions may occur due to EVM overshoot in the leading Symbol of the transmitted signal. However, this malfunction can be avoided by inserting an AMP stabilization signal in the time domain preceding the time domain of the transmitted signal.

[0013] However, the inventors of the present invention have encountered two new problems when adopting a configuration in which an AMP stabilization signal is interrupted in the above-mentioned wireless communication device. These two problems will be explained below. In the following explanation, the above-mentioned wireless communication device will be described as an AAS (RU (Radio Unit)) that transmits a DL signal as a transmission signal to each UE (User Equipment: mobile terminal).

[0014] The first challenge: In Europe, because countries share land borders, TDD configurations can differ between neighboring countries separated by national borders. Hereafter, we will refer to these differences in TDD configurations between neighboring countries as "heterogeneous TDD configurations." As shown in Figure 1, if we represent the TDD configuration using "D (DL Frame)," "U (UL Frame)," and "S (Special Subframe)," then, for example, Germany's TDD configuration is "DDDSU." In contrast, the TDD configurations of three neighboring countries of Germany—Austria, Switzerland, and France—differ from Germany's TDD configuration.

[0015] Therefore, especially in Europe, when building 5G systems as TDD systems, it is necessary to address DL blanking when heterogeneous TDD configurations occur between neighboring countries across national borders. DL blanking is a standard that establishes a section where DL signals are not transmitted in order to avoid interference of DL signals with UL signals transmitted from AAS(RUs) in neighboring countries. Specifically, in the non-transmission section, the AAS(RU) controls TX to be ON but does not transmit DL signals. This DL blanking standard is defined in Non-Patent Literature 1. Furthermore, it is expected that AAS(RUs) equipped with beam forming functions that require multiple TXs will become mainstream in 5G systems. Therefore, for example, it is conceivable to manufacture AAS(RUs) for inland use that do not require DL blanking and AAS(RUs) that are deployed near borders with heterogeneous TDD configurations and require DL blanking in advance, before shipment from the factory. However, the deployment plan of AAS(RUs) obtained from operators has many unpredictable aspects. Furthermore, if AAS(RU) is created differently, AAS(RU) initially shipped for inland use and then deployed to border areas requiring DL Blanking support will require customization via Remote Software Update, increasing deployment constraints. For this reason, creating different AAS(RU) is not preferred by operators.

[0016] Therefore, it is important to ship AAS(RU) that can autonomously determine whether to implement or stop the AMP stabilization signal interrupt, without having to pre-create AAS(RU) that support DL Blanking or not.

[0017] The second challenge: Furthermore, in order to reduce the power consumption of 5G systems, particularly in Europe, it is necessary to support a Micro-sleep Mode that involves turning the transmitting AMP on and off for each DL Symbol. However, if the AAS(RU) were to autonomously detect the presence or absence of DL signals for each DL Symbol for each TX within the AAS(RU) and arbitrarily interrupt the AMP stabilization signal based on its own judgment, the following problems would arise. For example, suppose a DL signal is present at a certain DL Symbol from a certain TX. In this case, the AAS(RU) would interrupt the beginning of the DL Symbol with an AMP stabilization signal for the TX that was determined to have a DL signal. However, if another TX was transmitting a DL signal at the DL Symbol preceding that DL Symbol, the radiation of the AMP stabilization signal would interfere with the DL signal transmitted by the other TX in the propagation space.

[0018] Furthermore, when spatially multiplexing multiple terminals using beam forming from an AAS (base station) such as MU-MIMO (Multi-User MIMO) or Massive-MIMO, algorithms such as the Zero-Forcing method are used. In this case, in order to make the DL (Down-Link) radiated signals from the AAS to each terminal spatially orthogonal, a Null pattern is formed for the radiation pattern to other terminals in the direction of the beam towards each terminal, according to the UL (Up-Link) signals received by each receiver of the AAS from the multiple terminals. This enables spatial multiplexing to multiple terminals at the AAS. At that time, the DL radiated signals to each terminal and the Null patterns to other terminals are uniquely formed from the UL received signals that arrive at the AAS from each terminal. However, if an AMP stabilization signal, which is completely uncorrelated with the UL signals from each terminal, is radiated just before the DL in the DL radiated signal, this AMP stabilization signal will interfere with the transmission radiation that radiates the DL symbol before the DL symbol. As a result, the orthogonality of the spatial multiplexing between multiple terminals formed in the interfered DL signal portion will be disrupted by this AMP stabilization signal. This can lead to a degradation in the SINR (Signal to Interference and Noise Ratio) of the DL signal itself to each terminal, and a decrease in null depth, resulting in increased interference from other terminal beams, ultimately leading to a degradation in DL throughput to each terminal.

[0019] Therefore, simply improving the EVM overshoot of the leading DL symbol by haphazardly interrupting the leading DL symbol with an AMP stabilization signal based on the autonomous judgment of the AAS(RU) is insufficient to avoid interference caused by the radiation of the AMP stabilization signal.

[0020] As described above, in wireless communication devices equipped with a transmission amplifier with poor Gate / Drain Lag, simply improving the EVM overshoot at the beginning of the transmission signal by interrupting the AMP stabilization signal at the beginning of the transmission signal is insufficient, and the aforementioned problems arise.

[0021] Therefore, in the wireless communication device described above, when adopting a configuration in which an AMP stabilization signal is interrupted in the time domain before the time domain of the DL signal, it is necessary to autonomously determine the implementation and stop of the interruption of the AMP stabilization signal and avoid interference caused by the radiation of the AMP stabilization signal.

[0022] In view of the above problems, an object of the present disclosure is to be able to autonomously determine the implementation and stop of the interruption of the stabilization signal when adopting a configuration in which the stabilization signal is interrupted in the time domain before the time domain of the transmission signal, and to provide a wireless communication device, a wireless communication system, and a wireless communication method capable of avoiding interference caused by the radiation of the stabilization signal.

Means for Solving the Problems

[0023] A wireless communication device according to one aspect includes: a plurality of transmitters; [[ID=1 four]] a plurality of signal processing units provided corresponding to each of the plurality of transmitters and arranged in front of the corresponding transmitter; a plurality of transmission amplifiers provided corresponding to each of the plurality of transmitters and arranged after the corresponding transmitter; a determination unit, and the determination unit detects the presence or absence of a transmission signal for each transmission symbol for each of the plurality of transmitters, when it is detected that the transmission signal is present in an arbitrary transmitter among the plurality of transmitters, and it is detected that there is no transmission signal in all of the plurality of transmitters in the transmission symbol before the transmission symbol in which the arbitrary transmitter transmits the transmission signal, a stabilization signal for stabilizing the characteristics of an arbitrary transmission amplifier provided corresponding to the arbitrary transmitter is interrupted in the time domain before the time domain of the transmission signal. By controlling an arbitrary signal processing unit provided corresponding to the arbitrary transmitter, the stabilization signal is passed through the arbitrary transmitter and the arbitrary transmission amplifier before the transmission signal passes through the arbitrary transmitter and the arbitrary transmission amplifier.

[0024] A wireless communication system according to one aspect is The wireless communication device, The system includes a preprocessor positioned in front of the wireless communication device, which performs alignment of the transmission signals in the plurality of transmitters within the wireless communication device and inputs the aligned transmission signals to the wireless communication device.

[0025] One aspect of wireless communication method is: A wireless communication method performed by a wireless communication device comprising a plurality of transmitters and a plurality of transmitting amplifiers provided corresponding to each of the plurality of transmitters, each of which is positioned downstream of the corresponding transmitter, For each of the aforementioned multiple transmitters, for each transmission symbol, the step of detecting the presence or absence of a transmission signal, The process includes the step of detecting that the transmission signal is present in any of the plurality of transmitters, and detecting that the transmission signal is not present in any of the plurality of transmitters at the transmission symbol preceding the transmission symbol in which the arbitrary transmitter transmits the transmission signal, by interrupting the time domain preceding the time domain of the transmission signal with a stabilization signal for stabilizing the characteristics of an arbitrary transmission amplifier provided in correspondence with the arbitrary transmitter, thereby causing the stabilization signal to pass through the arbitrary transmitter and the arbitrary transmission amplifier before the transmission signal passes through the arbitrary transmitter and the arbitrary transmission amplifier. [Effects of the Invention]

[0026] According to the above-described embodiment, when employing a configuration in which a stabilization signal is inserted into the time domain preceding the time domain of the transmitted signal, it is possible to autonomously determine when to insert and stop the stabilization signal, and it is possible to provide a wireless communication device, wireless communication system, and wireless communication method that can avoid interference caused by the radiation of the stabilization signal. [Brief explanation of the drawing]

[0027] [Figure 1] This figure shows examples of TDD configurations in Germany's neighboring countries. [Figure 2]This diagram illustrates the outline of each embodiment. [Figure 3] This figure shows an example of the time arrangement of an AMP stabilization signal. [Figure 4] This timing chart shows an example of how processing start timing changes in AAS due to AMP stabilization signal interrupts. [Figure 5] This figure shows an example configuration of AAS(RU) according to Embodiment 1. [Figure 6] This figure shows an example in which an AMP stabilization signal is inserted into the time domain preceding the time domain of the DL signal in the AAS(RU) according to Embodiment 1. [Figure 7] This is a flowchart illustrating a general example of the operation of AAS(RU) according to Embodiment 1. [Figure 8] This diagram illustrates a specific example of operation of the AAS(RU) according to Embodiment 1. [Figure 9] This figure shows an example configuration of a wireless communication system according to Embodiment 2. [Figure 10] This figure illustrates a specific example of operation of the wireless communication system according to Embodiment 2. [Figure 11] This figure illustrates a specific example of operation of the wireless communication system according to Embodiment 2. [Figure 12] This figure illustrates a specific example of operation of the wireless communication system according to Embodiment 2. [Figure 13] This figure shows an example of a computer hardware configuration that implements some of the functions of the wireless communication device related to this disclosure. [Modes for carrying out the invention]

[0028] Embodiments of this disclosure will be described below with reference to the drawings. Note that the following description and drawings have been omitted and simplified as appropriate for clarity of explanation. Furthermore, the same elements are denoted by the same reference numerals in the following drawings, and redundant explanations have been omitted where necessary. Also, the specific numerical values ​​shown below are merely examples to facilitate understanding of this disclosure and are not limiting.

[0029] <Overview of the Embodiment> Before describing the details of each embodiment of this disclosure, an overview of each embodiment will be given. In the following, the wireless communication device equipped with the transmitting AMP will be assumed to be an AAS(RU) that transmits a DL signal as a transmission signal to each UE.

[0030] Figure 2 is a diagram illustrating the outline of each embodiment of the present disclosure. In Figure 2, A1 shows the TDD configuration for Germany. Furthermore, A1 shows the interrupt of the AMP stabilization signal implemented by the AAS(RU) for inland use, which has the TDD configuration of A1 and does not require DL Blanking.

[0031] The AAS(RU) of A1 detects the presence or absence of a DL signal for each DL Symbol, for each of the multiple TXs that make up the AAS(RU). If the AAS(RU) of A1 detects the presence of a DL signal, it inserts an AMP stabilization signal into the time range preceding that DL Symbol (the time range of the DL signal).

[0032] Furthermore, in Figure 2, A2 shows a TDD configuration different from A1. Also, A3 shows the DL Blanking and AMP stabilization signal interrupts performed by an AAS(RU) with the TDD configuration of A1 when it is placed near the border of a neighboring country where an AAS(RU) with the TDD configuration of A2 is located.

[0033] A3 AAS(RU) implements DL blanking to avoid DL signal interference with UL signals transmitted from neighboring country RUs with A2 TDD configurations. Specifically, A3 AAS(RU) implements DL blanking in DL frames that overlap with A2 UL frames. A3 AAS(RU) also implements DL blanking in Special Subframes, but this is because DL blanking is mandated by the 5G standard.

[0034] Furthermore, the A3's AAS(RU) detects the presence or absence of a DL signal for each DL Symbol, for each of the multiple TXs that make up the AAS(RU). When the A3's AAS(RU) detects the presence of a DL signal, it inserts an AMP stabilization signal into the time range preceding that DL Symbol (the time range of the DL signal). However, in DL frames where DL blanking is performed, no DL signal is detected, so the AMP stabilization signal interruption is stopped.

[0035] Furthermore, if a DL signal is being transmitted by one of several TXs in a DL symbol preceding a DL symbol that emits an AMP stabilization signal, the emission of the AMP stabilization signal may interfere with that DL signal.

[0036] Therefore, if A3's AAS(RU) detects the presence of a DL signal at a DL symbol in any of the multiple TXs, it will stop the AMP stabilization signal interrupt if it also detects the presence of a DL signal at the DL symbol preceding that DL symbol in any of the multiple TXs.

[0037] In other words, A3's AAS(RU) detects the presence of a DL signal at a certain DL Symbol in any of the multiple TXs, and also detects that there is no DL signal at any of the multiple TXs at the DL Symbol preceding that DL Symbol, then it inserts an AMP stabilization signal into the time domain preceding that DL Symbol (the time domain of the DL signal).

[0038] In Figure 2, A4 shows the DL Blanking and AMP stabilization signal interrupts performed by an AAS(RU) with the TDD configuration of A2 when it is placed near the border of a neighboring country where an AAS(RU) with the TDD configuration of A3 is located.

[0039] A4 AAS(RU) implements DL blanking to avoid DL signal interference with UL signals transmitted from neighboring country AAS(RU) with A3 TDD configuration. Specifically, A4 AAS(RU) implements DL blanking in DL frames that overlap with A3 UL frames.

[0040] As described above, according to each embodiment of this disclosure, the AAS(RU) detects the presence or absence of a DL signal for each DL Symbol in each of the multiple TXs. When the AAS(RU) detects the presence of a DL signal at a certain DL Symbol in any of the multiple TXs, and also detects that there is no DL signal at any of the multiple TXs at the DL Symbol preceding that DL Symbol, it inserts an AMP stabilization signal into the time domain preceding that DL Symbol (the time domain of the DL signal). In this way, the AMP stabilization signal passes through the transmitting AMP before the DL signal passes through the transmitting AMP.

[0041] In this way, by inputting an AMP stabilization signal to the transmitting AMP before the first DL symbol of the DL signal is input to the transmitting AMP, the current collapse and gate / drain lag of the transmitting AMP are resolved early. This causes characteristic variations caused by the current collapse and gate / drain lag of the transmitting AMP to converge early, and stabilizes the nonlinear distortion characteristics of the transmitting AMP, such as Gain, Output, and AM-AM / AM-PM. As a result, many problems caused by EVM overshoot at the first DL symbol of the DL signal are avoided, and signal quality is guaranteed from the first DL symbol of the DL signal and any first DL symbol in the DL slot. Furthermore, since the AM-AM / AM-PM characteristics of the transmitting AMP in the section of the first DL symbol of the DL signal are already stable when the first DL symbol of the DL signal is input to the transmitting AMP, the first DL symbol of the DL signal and subsequent DL symbols are stably distortion-compensated by the DPD in the TX. This also contributes to the guarantee of signal quality from the first DL symbol of the DL signal.

[0042] Furthermore, in DL frames where DL blanking is being performed, the AAS(RU) will not detect the DL signal and will therefore stop interrupting the AMP stabilization signal. In this way, the AAS(RU) can autonomously decide whether to interrupt or stop the AMP stabilization signal, and can therefore be deployed at borders where DL blanking is required.

[0043] Furthermore, if AAS(RU) detects the presence of a DL signal at a certain DL symbol in any of the multiple TXs, and also detects that there are no DL signals at any of the multiple TXs at the DL symbol preceding that DL symbol, it will insert an AMP stabilization signal into the time domain preceding that DL symbol (the time domain of the DL signal). This prevents the radiation of the AMP stabilization signal from one TX from interfering with DL signals transmitted from another TX.

[0044] The following provides a more detailed explanation of the AMP stabilization signal.

[0045] Figure 3 shows an example of the time arrangement of an AMP stabilization signal. As shown in Figure 3, the AMP stabilization signal is placed, for example, within the time domain of the Tx On Transient period, which is the period for switching TX from Off to On. The Tx On Transient period is specified as 10 μsec in 3GPP (Third Generation Partnership Project, registered trademark) NR (New Radio).

[0046] Figure 4 is a timing chart showing an example of the change in processing start timing associated with the AMP stabilization signal interrupt in AAS(RU). As shown in Figure 4, in each embodiment, AAS(RU) inserts the AMP stabilization signal into the time domain preceding the DL signal's time domain. Therefore, if the AMP stabilization signal is 10 μsec long, AAS(RU) advances the timing of applying the control voltage TX_Enable On to TX to enable it in the TRX by 10 μsec. AAS(RU) also advances the timing of applying the control voltage AMP On to the transmit AMP to turn it on by 10 μsec.

[0047] The embodiments of this disclosure will be described below. In the following description, the wireless communication device according to each embodiment will be described as an AAS(RU) that transmits a DL signal as a transmission signal to each UE.

[0048] <Embodiment 1> Figure 5 shows an example configuration of the AAS(RU)10 according to this embodiment 1. Note that Figure 5 shows only the main components of the AAS(RU)10 according to this embodiment, and other components (for example, antennas, etc.) are omitted from the illustration.

[0049] As shown in Figure 5, the AAS(RU)10 according to this embodiment includes a determination unit 11, a plurality of signal processing units 12-0 to 12-m (where m is an integer of 1 or more), a plurality of TX units 13-0 to 13-m, and a plurality of transmitting AMP units 14-0 to 14-m. The TX units 13-0 to 13-m are transmitters, and the transmitting AMP units 14-0 to 14-m are GaN AMPs. Each of the signal processing units 12-0 to 12-m includes an IFFT (Inverse Fast Fourier Transform) unit 121, a signal storage and transmission unit 122, and an adder 123.

[0050] In the following, if the specific signal processing unit 12-0 to 12-m is not identified, it will be referred to as "signal processing unit 12" as appropriate. Similarly, TX13-0 to 13-m will be referred to as "TX13" as appropriate, and transmission AMP14-0 to 14-m will be referred to as "transmission AMP14" as appropriate.

[0051] The signal processing units 12-0 to 12-m are provided in correspondence to each of the TX13-0 to 13-m, and each of the signal processing units 12-0 to 12-m is positioned before the corresponding TX13. Transmit AMP14-0 to 14-m are provided in correspondence to each of TX13-0 to 13-m, and each of the transmit AMP14-0 to 14-m is positioned after the corresponding TX13.

[0052] The signal processing unit 12-0 receives DL signals transmitted by TX13-0 from a DU (Distributed Unit) / CU (Centralized Unit) (not shown) located in front of the AAS(RU) 10. Similarly, the signal processing unit 12-m receives DL signals transmitted by TX13-m from the DU / CU.

[0053] The determination unit 11 detects the presence or absence of a DL signal for each DL Symbol (transmitted symbol) for every TX13-0 to 13-m. Then, if the determination unit 11 detects that any TX13 among TX13-0 to TX13-m has a DL signal, it detects the presence or absence of a DL signal for all TX13-0 to TX13-m at the DL Symbol preceding the DL Symbol that the arbitrary TX13 transmits the DL signal. If it detects that there is no DL signal for all TX13-0 to TX13-m, the determination unit 11 performs interrupt control of the AMP stabilization signal for the arbitrary TX13.

[0054] For example, suppose any TX13 is TX13-0. In this case, the determination unit 11 controls the signal processing unit 12-0 to insert the AMP stabilization signal into the time domain preceding the DL signal time domain. Specifically, the determination unit 11 sends an instruction to the signal storage / transmission unit 122 within the signal processing unit 12-0 to send the AMP stabilization signal. When the AMP stabilization signal is input to the transmitting AMP 14-0, it causes the current collapse and Gate / Drain Lag of the transmitting AMP 14-0 to converge early, thereby stabilizing the Gain, output, and nonlinear distortion characteristics of the transmitting AMP 14-0 early.

[0055] The signal processing units 12-0 to 12-m perform substantially the same operation. Similarly, the TX units 13-0 to 13-m perform substantially the same operation. Furthermore, the transmit amplifiers 14-0 to 14-m perform substantially the same operation. Therefore, the operation of the signal processing units 12-0, TX unit 13-0, and transmit amplifier 14-0 will be described as representative of each.

[0056] The IFFT unit 121 converts the DL signal input from the DU / CU from a frequency domain signal to a time domain signal. For example, the determination unit 11 detects the presence or absence of a DL signal in TX13-0 by performing a threshold determination in the frequency domain prior to the IFFT unit 121.

[0057] The signal storage and transmission unit 122 stores an AMP stabilization signal for stabilizing the characteristics of the transmitting AMP 14-0. Furthermore, when the signal storage and transmission unit 122 receives an instruction from the determination unit 11 to transmit an AMP stabilization signal, it transmits the AMP stabilization signal to the adder 123.

[0058] When an AMP stabilization signal is sent from the signal storage / transmission unit 122, the adder 123 adds the AMP stabilization signal to the time range preceding the time range of the DL signal output from the IFFT unit 121. In this way, the AMP stabilization signal is inserted into the time range preceding the time range of the DL signal. At this time, the determination unit 11 calculates the time when the DL signal exists by considering the processing time of TX13-0 from the radiation time of the DL signal from the antenna. Then, the determination unit 11 sends an instruction to send the AMP stabilization signal to the signal storage / transmission unit 122 at a timing such that the AMP stabilization signal is inserted into the beginning of the time obtained by reverse calculation. Figure 6 shows an example in which the AMP stabilization signal is inserted into the time range preceding the time range of the DL signal. This allows the AMP-stabilized signal to pass through TX13-0 and the transmit AMP14-0 before the DL signal passes through TX13-0 and the transmit AMP14-0.

[0059] In this case, during TDD operation of AAS(RU)10, the time period preceding the time period of the DL signal is, for example, the Tx On Transient period, which is the period for switching TX13-0 from Off to On. Therefore, the time width of the AMP stabilization signal is set within the time width of the Tx On Transient period. The Tx On Transient period is specified as 10 μsec in 3GPP NR.

[0060] Furthermore, the frequency bandwidth of the AMP stabilization signal is set to, for example, the frequency bandwidth of the Component Carrier used to transmit the DL signal. Furthermore, the power level of the AMP stabilization signal is set to a power level at which, for example, the output of the transmitting AMP14-0 reaches the maximum rated RMS (Root Mean Square) level, and is the same power level as the DL signal.

[0061] TX13-0 is located downstream of signal processing unit 12-0 and converts the DL signal or AMP stabilized signal output from signal processing unit 12-0 from an IQ (In-Phase / Quadrature-Phase) signal to an RF (Radio Frequency) signal, which is then output to the transmitting AMP 14-0. TX13-0 is located within a transceiver (TRX) not shown. Furthermore, as mentioned above, TX13-0 includes DPP and other components, but these are not shown in the illustration.

[0062] The transmitting AMP14-0 is located after the TX13-0 and amplifies and outputs the DL signal or AMP stabilized signal output from the TX13-0. The DL signal or AMP stabilized signal output from the transmitting AMP14-0 is transmitted to each UE via an antenna (not shown).

[0063] Figure 7 is a flowchart illustrating a schematic example of the operation of AAS(RU)10 according to this embodiment 1. As shown in Figure 7, the determination unit 11 detects the presence or absence of a DL signal for each DL Symbol, for every TX13-0 to TX13-m (step S11).

[0064] If the determination unit 11 detects that any TX13 among TX13-0 to TX13-m has a DL signal (Yes in step S12), it detects the presence or absence of a DL signal for all TX13-0 to TX13-m at the DL Symbol preceding the DL Symbol to which any TX13 transmits the DL signal (step S13).

[0065] If the determination unit 11 detects that there are no DL signals in any of TX13-0 to TX13-m (Yes in step S14), it sends an instruction to send an AMP stabilization signal to any signal processing unit 12 corresponding to any TX13. Within any signal processing unit 12, the signal storage / transmission unit 122 sends the AMP stabilization signal to the adder 123, and the adder 123 adds the AMP stabilization signal to the time range preceding the time range of the DL signal output from the IFFT unit 121. In this way, the AMP stabilization signal is inserted into the time range preceding the DL Symbol (time range of the DL signal) in which the DL signal was detected (step S15).

[0066] Therefore, first, the AMP stabilization signal passes through any TX13 and any transmit AMP14 corresponding to any TX13 (step S16). This stabilizes the gain, output, and nonlinear distortion characteristics of any transmit AMP14. Then, the DL signal passes through any TX13 and any transmit AMP14 (step S17).

[0067] Figure 8 illustrates a specific example of operation of the AAS(RU)10 according to this embodiment 1. In the example shown in Figure 8, the AAS(RU)10 is equipped with 64 TX #0 to #63 as TX13. Each UL Slot consists of 14 UL Symbols, and each DL Slot consists of 14 DL Symbols. The AMP stabilization signal is represented by "A", the DL signal by "TX_DATA", and the UL signal by "RX_DATA" (the same applies in Figures 10 to 12 described later).

[0068] As shown in Figure 8, DL Symbol #0 has DL signals in TX #0~#7 and TX #62~#63. Also, since DL Symbol #0 is the first symbol of the DL slot, there are no DL Symbols before DL Symbol #0. Therefore, an AMP stabilization signal is inserted into the time domain before DL Symbol #0 in TX #0~#7 and TX #62~#63.

[0069] Furthermore, in DL Symbol #2, DL signals are present in TX #0 to #63. Also, in DL Symbol #1, which precedes DL Symbol #2, there are no DL signals in any of TX #0 to #63. Therefore, an AMP stabilization signal is inserted into TX #0 to #63 in the time domain prior to DL Symbol #2.

[0070] Furthermore, in DL Symbol #8, only TX #0 has a DL signal. Also, in DL Symbol #7, which precedes DL Symbol #8, none of TX #0 to #63 have DL signals. Therefore, an AMP stabilization signal is inserted into TX #0 in the time domain prior to DL Symbol #8.

[0071] On the other hand, at DL Symbol #9, DL signals are present at TX #0 to #63. However, at DL Symbol #8, which precedes DL Symbol #9, TX #0 also has a DL signal. In this case, if an AMP stabilization signal is interrupted for TX #1 to #63 in the time domain before DL Symbol #9, the radiation of these AMP stabilization signals may interfere with DL Symbol #8, which is the DL signal from TX #0. Therefore, the interruption of AMP stabilization signals into the time domain before DL Symbol #9 for TX #1 to #63 is stopped.

[0072] As described above, according to this embodiment 1, the determination unit 11 detects that there is a DL signal in any TX13 among TX13-0 to TX13-m, and if it detects that there is no DL signal in any of TX13-0 to TX13-m at the DL Symbol preceding the DL Symbol to which any TX13 transmits a DL signal, it inserts an AMP stabilization signal into the time domain preceding the time domain of the DL signal. In this way, the AMP stabilization signal passes through any TX13 and any transmitting AMP14 before the DL signal passes through any TX13 and any transmitting AMP14 corresponding to any TX13.

[0073] In this way, by inputting an AMP stabilization signal to any transmitting AMP14 before the leading DL symbol of the DL signal is input to any transmitting AMP14, the current collapse and gate / drain lag of any transmitting AMP14 are resolved early. This causes characteristic variations caused by the current collapse and gate / drain lag of any transmitting AMP14 to converge early, and stabilizes the nonlinear distortion characteristics of any transmitting AMP14, such as gain, output, and AM-AM / AM-PM. This suppresses overshoot in the EVM of the leading DL symbol of the DL signal, and maintains the communication quality of the leading DL symbol of the DL signal. As a result, many problems caused by overshoot in the EVM of the leading DL symbol of the DL signal are avoided, and signal quality is guaranteed from the leading DL symbol of the DL signal and any leading DL symbol in the DL slot. Furthermore, when the initial DL Symbol of the DL signal is input to any transmitting AMP14, the AM-AM / AM-PM characteristics of the transmitting AMP14 in the initial DL Symbol section of the DL signal are already stable. Therefore, the initial DL Symbol and subsequent DL Symbols of the DL signal are stably distortion-compensated by the DPD in any TX13. This also contributes to ensuring signal quality from the initial DL Symbol of the DL signal.

[0074] Furthermore, the determination unit 11 does not detect DL signals in DL Symbols in sections where DL Blanking is being performed, and therefore stops the interruption of the AMP stabilization signal. In this way, the AAS(RU)10 can autonomously determine whether to perform or stop the interruption of the AMP stabilization signal, and can therefore be deployed at borders where DL Blanking support is required.

[0075] Furthermore, the determination unit 11 detects that any TX13 among TX13-0 to TX13-m has a DL signal, and if it detects that there are no DL signals in any of TX13-0 to TX13-m at the DL Symbol preceding the DL Symbol to which any TX13 transmits a DL signal, it inserts an AMP stabilization signal into the time domain preceding that DL Symbol (the time domain of the DL signal). This prevents the radiation of the AMP stabilization signal from any TX13 from interfering with DL signals transmitted from other TX13s.

[0076] <Embodiment 2> Figure 9 shows an example of the configuration of a wireless communication system according to this second embodiment. As shown in Figure 9, the wireless communication system according to this second embodiment comprises the AAS(RU)10 according to the first embodiment described above, and a DU / CU20 positioned before the AAS(RU)10. The DU / CU20 is an example of a preprocessor.

[0077] The DU / CU20 aligns the DL signals in multiple TX13s within the AAS(RU)10 and inputs the aligned DL signals back into the AAS(RU)10.

[0078] Figures 10 to 12 illustrate specific operational examples of the wireless communication system according to this second embodiment. As described above, AAS(RU)10 detects that any of the multiple TX13s have a DL signal, and if it detects that none of the multiple TX13s have a DL signal at the DL Symbol preceding the DL Symbol that the arbitrary TX13 transmits the DL signal, it inserts an AMP stabilization signal into the time domain before the time domain of the DL signal.

[0079] Here, we consider the case where DL signals are arranged as shown in Figure 10. In the example in Figure 10, DL signals are present at DL Symbol #9 for TX #1, #2, #4, #6~#8, #10, and #62. However, there are TX signals with DL signals at DL Symbol #8, which precedes DL Symbol #9. Therefore, AAS(RU)10 stops interrupting TX #1, #2, #4, #6~#8, #10, and #62 with AMP stabilization signals in the time domain prior to DL Symbol #9 in order to avoid interference between the AMP stabilization signal radiation and the DL signals.

[0080] However, if the AMP stabilization signal interrupt is disabled in TX #1, #2, #4, #6~#8, #10, and #62, the characteristics of the subsequent transmit AMP14 cannot be stabilized. As a result, an overshoot occurs in the EVM of the leading DL Symbol of the DL signal, which can lead to various malfunctions.

[0081] Therefore, as shown in Figure 11, the DU / CU20 performs alignment of DL signals in TX #0 to #63. For example, the DU / CU20 shifts DL signals forward or backward, converging all DL signals from TX #0 to #63 to a specific DL Symbol where there are many DL signals. In this way, the DU / CU20 puts DL Symbols into two states: DL Symbols where DL signals are present in all TX #0 to #63, and DL Symbols where DL signals are absent in all TX #0 to #63. In the example in Figure 11, the DU / CU20 shifts the DL signal of DL Symbol #9 in TX #1, #2, #4, #6 to #8, #10, and #62 forward and places it in DL Symbol #8, and shifts the DL signal of DL Symbol #9 in the remaining TXs backward and places it in DL Symbol #10.

[0082] As a result, the arrangement of DL signals in TX #0 to #63 is as shown in Figure 12, with DL Symbols #8 and #10 having DL signals for all TX #0 to #63, and DL Symbol #9 having no DL signals for any TX #0 to #63. As a result, AAS(RU)10 can interrupt TX #0~#63 with an AMP stabilization signal in the time domain before DL Symbol #8 and #10.

[0083] As described above, according to this second embodiment, the DU / CU20 aligns the DL signals in multiple TX13s within the AAS(RU)10 and inputs the aligned DL signals to the AAS(RU)10. This makes it possible to perform the AMP stabilization signal interrupt even in cases where the AMP stabilization signal interrupt could not be performed in the first embodiment described above. Other effects are the same as those of the first embodiment described above.

[0084] Although the present disclosure has been described above with reference to embodiments, the present disclosure is not limited to the embodiments described above. Various modifications to the structure and details of the present disclosure can be understood by those skilled in the art within the scope of the present disclosure.

[0085] For example, some functions of the wireless communication device related to this disclosure can be realized by having a processor such as a CPU (Central Processing Unit) execute a program. Figure 13 shows an example of the hardware configuration of a computer 90 that implements some of the functions of the wireless communication device according to this disclosure. As shown in Figure 13, the computer 90 includes a processor 91 and memory 92.

[0086] The processor 91 may be, for example, a microprocessor, a CPU, or an MPU (Micro Processing Unit). The processor 91 may include multiple processors.

[0087] Memory 92 is composed of a combination of volatile and non-volatile memory. Memory 92 may also include storage located away from the processor 91. In this case, the processor 91 may access memory 92 via an I(Input) / O(Output) interface, which is not shown.

[0088] A program is stored in memory 92. This program, when loaded into the computer 90, includes a set of instructions (or software code) that causes the computer 90 to perform some of the functions of the AAS(RU)10 according to the above-described embodiment. The components of the AAS(RU)10 described above may also be realized by the processor 91 loading and executing the program stored in memory 92. Furthermore, the components of the AAS(RU)10 that have storage functions described above may also be realized by memory 92.

[0089] Furthermore, the programs described above may be stored on non-temporary computer-readable media or tangible storage media. Examples, but not limited to, include random-access memory (RAM), read-only memory (ROM), flash memory, solid-state drives (SSDs) or other memory technologies, CD-ROMs, digital versatile discs (DVDs), Blu-ray® discs or other optical disc storage, magnetic cassettes, magnetic tapes, magnetic disk storage or other magnetic storage devices. The programs may also be transmitted over temporary computer-readable media or communication media. Examples, but not limited to, include electrical, optical, acoustic, or other forms of propagating signals.

[0090] Furthermore, some functions of the DU / CU20 preprocessor related to this disclosure may also be implemented by the computer 90 shown in Figure 13. [Explanation of Symbols]

[0091] 10 AAS(RU) 11 Judgment section 12-0~12-m Signal Processing Unit 13-0~13-m TX 14-0~14-m Transmission AMP 121 IFFT section 122 Signal storage and transmission unit 123 Adder 20 DU / CU 90 Computer 91 processors 92 memory

Claims

1. Multiple transmitters, A plurality of signal processing units are provided corresponding to each of the plurality of transmitters, and each is positioned in front of the corresponding transmitter, A plurality of transmitting amplifiers are provided corresponding to each of the plurality of transmitters, and each is positioned downstream of the corresponding transmitter. It comprises a determination unit and, The determination unit, For each of the aforementioned multiple transmitters, for each transmission symbol, the presence or absence of a transmission signal is detected. When it is detected that the transmission signal is present in any of the multiple transmitters, and when it is detected that none of the multiple transmitters have the transmission signal at the transmission symbol preceding the transmission symbol in which the arbitrary transmitter transmits the transmission signal, the arbitrary signal processing unit provided in conjunction with the arbitrary transmitter is controlled to cause a stabilization signal for stabilizing the characteristics of an arbitrary transmission amplifier provided in conjunction with the arbitrary transmitter to be inserted into the time domain preceding the time domain of the transmission signal, thereby causing the stabilization signal to pass through the arbitrary transmitter and the arbitrary transmission amplifier before the transmission signal passes through the arbitrary transmitter and the arbitrary transmission amplifier. Wireless communication device.

2. Each of the aforementioned plurality of signal processing units is: A signal storage and transmission unit that stores the stabilization signal and transmits the stabilization signal when it receives a transmission instruction, The aforementioned transmission signal is converted from a frequency domain signal to a time domain signal by an IFFT (Inverse Fast Fourier Transform) unit, The system includes an adder that, when the signal storage and transmission unit transmits the stabilized signal, adds the stabilized signal transmitted from the signal storage and transmission unit to the time range preceding the time range of the transmitted signal output from the IFFT unit, The determination unit, When it is detected that the transmission signal is present in any of the aforementioned transmitters, and when it is detected that none of the plurality of transmitters have the transmission signal at the transmission symbol preceding the transmission symbol in which the aforementioned transmitter transmits the transmission signal, the transmission instruction is sent to the signal storage and transmission unit in the aforementioned signal processing unit. The wireless communication device according to claim 1.

3. The determination unit, In the frequency domain preceding the IFFT section, the presence or absence of the transmission signal in each of the plurality of transmitters is detected. The wireless communication device according to claim 2.

4. When the wireless communication device performs TDD (Time Division Duplex) operation, the time width of the stabilization signal is set within the time width of the period required to switch the transmitter from Off to On. The wireless communication device according to claim 1.

5. The frequency bandwidth of the stabilized signal is set to the frequency bandwidth of the component carrier used for transmitting the transmitted signal. The wireless communication device according to claim 1.

6. The power level of the stabilization signal is set to a power level at which the output of the transmitting amplifier reaches the maximum rated RMS (Root Mean Square) level, and is the same power level as the transmitting signal. The wireless communication device according to claim 1.

7. The stabilization signal, when input to the transmitting amplifier, generates a current collapse and gate / drain lag in the transmitting amplifier, thereby stabilizing the gain, output, and nonlinear distortion characteristics of the transmitting amplifier. The wireless communication device according to claim 1.

8. The aforementioned transmitting amplifier is an amplifier that uses a GaN (Gallium Nitride) FET (Field Effect Transistor). The wireless communication device according to claim 1.

9. A wireless communication device according to any one of claims 1 to 8, The system includes a preprocessor positioned in front of the wireless communication device, which performs alignment of the transmission signals in the plurality of transmitters within the wireless communication device and inputs the aligned transmission signals to the wireless communication device. Wireless communication system.

10. A wireless communication method performed by a wireless communication device comprising a plurality of transmitters and a plurality of transmitting amplifiers provided corresponding to each of the plurality of transmitters, each of which is positioned downstream of the corresponding transmitter, For each of the aforementioned multiple transmitters, for each transmission symbol, the step of detecting the presence or absence of a transmission signal, The process includes the step of detecting that the transmission signal is present in any of the plurality of transmitters, and detecting that the transmission signal is not present in any of the plurality of transmitters at the transmission symbol preceding the transmission symbol in which the arbitrary transmitter transmits the transmission signal, by interrupting the time domain of the transmission signal with a stabilization signal for stabilizing the characteristics of an arbitrary transmission amplifier provided in correspondence with the arbitrary transmitter, so that the stabilization signal passes through the arbitrary transmitter and the arbitrary transmission amplifier before the transmission signal passes through the arbitrary transmitter and the arbitrary transmission amplifier. Wireless communication method.

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