Communication device and communication system

Abstract

To restrict degradation of communication quality when a transmission device applies backoff.SOLUTION: A communication device 1 includes a receiving part 11 for receiving a backoff change amount indicating a change an amount of a backoff amount from a reference value at a transmission device and a transmission signal transmitted by the transmission device, from the transmission device, and a compensation part 141 for compensating distortion of the transmission signal using a compensation model used for compensation process for distortion of the transmission signal transmitted by the transmission device determined based on the backoff change amount.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a communication device and a communication system. [Background technology]

[0002] A known technique is backoff, which limits the maximum output power level in a communication device so that a signal in a region where the characteristics of a power amplifier are linear is output (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2019-510392 Summary of the Invention [Problem to be solved by the invention]

[0004] It is assumed that a transmitter may decrease the backoff to improve the efficiency of its power amplifier, or increase the backoff to reduce interference with other nearby communication devices. When the transmitter changes the backoff, the state of nonlinear distortion in the signal received by the receiver from the transmitter changes. When the state of nonlinear distortion in the received signal changes, the receiver is unable to properly compensate for the distortion in the received signal, resulting in a problem of degraded communication quality.

[0005] The present invention has been made in view of these points, and has as its object to suppress a decrease in communication quality when a transmitting device performs backoff. [Means for solving the problem]

[0006] A communication device of a first aspect of the present invention has a receiving unit that receives from the transmitting device a backoff change amount indicating the amount by which the backoff amount in the transmitting device has changed from a reference value and a transmission signal transmitted by the transmitting device, and a compensation unit that compensates for distortion of the transmission signal using a compensation model that is determined based on the backoff change amount and is used in processing to compensate for distortion of the transmission signal transmitted from the transmitting device.

[0007] The communication device may further have a memory unit that stores a plurality of the compensation models in association with back-off change amounts, and the compensation unit may determine the compensation model stored in the memory unit in association with the back-off change amount received by the receiving unit as the compensation model to be used in the process of compensating for distortion in the transmission signal.

[0008] The communication device may further include a model creation unit that, when a reference signal, which is the transmission signal received by the receiving unit and has known characteristics, and a back-off change amount are input, creates the compensation model corresponding to the back-off change amount based on the reference signal.

[0009] The model creation unit may create the compensation model that can reduce the difference between a standard reference signal in an undistorted state and the reference signal.

[0010] The model creation unit may create a plurality of the compensation models, and determine one of the created compensation models that has a relatively good signal quality after the compensation unit compensates for the reference signal as the compensation model corresponding to the back-off change amount.

[0011] A communication device of a second aspect of the present invention includes a receiving unit that receives backoff change information indicating that a backoff amount in a transmitting device has changed and a transmission signal transmitted by the transmitting device, a model creation unit that, when the receiving unit receives the backoff change information, creates a compensation model based on the reference signal, which is the transmission signal whose characteristics are known, to be used in processing to compensate for distortion in the transmission signal transmitted from the transmitting device, and a compensation unit that compensates for distortion in the transmission signal using the compensation model created by the model creation unit.

[0012] The compensation unit may cause the model creation unit to start an operation of creating the compensation model when the receiving unit receives the backoff change information, and may cause the model creation unit to stop an operation of creating the compensation model after the model creation unit has created the compensation model.

[0013] A third aspect of the present invention provides a communication system comprising a transmitting device and a receiving device that receives a transmission signal transmitted by the transmitting device, wherein the transmitting device has a back-off control unit that changes a back-off amount, and a transmitting unit that transmits a back-off change amount, which is a change amount from a reference value of the back-off amount, and the transmission signal, and the receiving device has a receiving unit that receives the back-off change amount and the transmission signal, and a compensation unit that compensates for distortion of the transmission signal using a compensation model that is determined based on the back-off change amount and is used in processing to compensate for distortion of the transmission signal transmitted from the transmitting device.

[0014] A fourth aspect of the present invention provides a communication system comprising a transmitting device and a receiving device that receives a transmission signal transmitted by the transmitting device, wherein the transmitting device has a back-off control unit that changes a back-off amount, and a transmitting unit that transmits back-off change information indicating that the back-off amount has changed and the transmission signal, and the receiving device has a receiving unit that receives the back-off change information and the transmission signal, and when the receiving unit receives the back-off change information, a model creation unit that, when the receiving unit receives a reference signal that is the transmission signal with known characteristics, creates a compensation model based on the reference signal to be used in processing to compensate for distortion in the transmission signal transmitted from the transmitting device, and a compensation unit that compensates for distortion in the transmission signal using the compensation model created by the model creation unit. to provide. [Effects of the Invention]

[0015] According to the present invention, it is possible to suppress a decrease in communication quality when a transmitting device performs backoff. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a diagram illustrating an overview of a communication system S1 according to a first embodiment. [Figure 2] 1 is a diagram showing a configuration of a communication device 1 according to a first embodiment. [Figure 3] FIG. 2 is a diagram showing an outline of a compensation model stored in a storage unit 13. [Figure 4] FIG. 10 is a diagram showing a configuration of a communication device 10 according to a second embodiment. [Figure 5] FIG. 10 is a diagram illustrating the operation of a model creating unit 145. [Figure 6] FIG. 10 is a diagram showing the configuration of a communication system S2 according to a third embodiment. [Figure 7] 4 is a flowchart showing the flow of processing in the communication device 10. DETAILED DESCRIPTION OF THE INVENTION

[0017] [Outline of communication system S1] First Embodiment 1 is a diagram illustrating an overview of a communication system S1. The communication system S1 includes a communication device 1A and a communication device 1B. The communication device 1A functions as a transmitting device, and the communication device 1B functions as a receiving device. The communication device 1A and the communication device 1B are, for example, devices having a wireless communication function, and can transmit a signal from the communication device 1A to the communication device 1B by radio waves.

[0018] The communication device 1A has a power amplifier and performs backoff by inputting a signal with a power level lower than the maximum power that can be input to the power amplifier. The communication device 1A changes the backoff amount, which is the difference between the output saturation power level of the power amplifier and the maximum amplitude level of the signal input to the power amplifier, according to various conditions.

[0019] For example, when there is a possibility of interference with other nearby communication devices, the communication device 1A increases the backoff amount to suppress the interference, and when there is a low possibility of interference and it is better to improve the efficiency of the power amplifier, the backoff amount decreases.In the following description, the amount by which the backoff amount changes from a reference value (e.g., an initial value) is referred to as the backoff change amount.

[0020] Communication device 1A outputs a transmission signal and transmits a back-off variation to communication device 1B. Communication device 1A transmits the back-off variation, for example, via a control channel of the physical layer, the MAC layer, or RRC signaling in a wireless communication channel between communication device 1A and communication device 1B. Communication device 1B stores a compensation model that compensates for nonlinear distortion in the received transmission signal, and can obtain a distortion-compensated signal by inputting the transmission signal to the compensation model.

[0021] When communication device 1A changes the back-off amount, the distortion characteristics of the transmission signal also change. Therefore, communication device 1B can compensate for the distortion of the transmission signal by switching the compensation model based on the back-off change amount received from communication device 1A, using a compensation model suitable for compensating for the distortion of the transmission signal after the back-off amount has changed. As a result, even if the back-off amount of communication device 1A changes, communication device 1B can appropriately compensate for the distortion, and therefore communication device 1B can prevent a decrease in communication quality (e.g., SNR).

[0022] Note that communication device 1A and communication device 1B may have equivalent communication functions, or may have different communication functions. Communication device 1A is, for example, a base station device, and communication device 1B is, for example, a communication terminal. In the following explanation, the configuration and operation of communication device 1 will be explained assuming that communication device 1A and communication device 1B have equivalent functions. Communication device 1A and communication device 1B may have some of the functions of communication device 1 described below.

[0023] 2 is a diagram showing the configuration of a communication device 1 according to the first embodiment. The communication device 1 includes a receiving unit 11, a transmitting unit 12, a storage unit 13, and a control unit 14. The control unit 14 includes a compensation unit 141, a received signal processing unit 142, a transmission signal generation unit 143, and a back-off control unit 144.

[0024] Compensation unit 141 and received signal processing unit 142 in Fig. 2 function when communication device 1 operates as communication device 1B in Fig. 1. Transmission signal generation unit 143 and back-off control unit 144 in Fig. 2 function when communication device 1 operates as communication device 1A in Fig. 1.

[0025] The receiver 11 receives from a transmitter (e.g., communication device 1A) a back-off variation indicating the amount by which the back-off amount in the transmitter has changed from a reference value, and a transmission signal transmitted by the transmitter. The receiver 11 inputs the received transmission signal to the compensation unit 141.

[0026] Transmitter 12 transmits a signal to another communication device. When transmitter 12 functions as communication device 1A, for example, transmitter 12 transmits a transmission signal input from transmission signal generator 143 and a back-off change amount input from back-off controller 144. Transmitter 12 has a power amplifier, and amplifies the signal input from transmission signal generator 143 before transmitting it.

[0027] The storage unit 13 has storage media such as a ROM (Read Only Memory), a RAM (Random Access Memory), and an SSD (Solid State Drive). The storage unit 13 stores a program executed by the control unit 14. The storage unit 13 also stores a compensation model used by the compensation unit 141 to compensate for distortion in the transmission signal received by the receiving unit 11.

[0028] The compensation model may take any form, for example, a DPoD (Digital Post-Distortion) model. The compensation model may be a polynomial type or may use a neural network. The compensation model may be notified from the transmitting device, or may be a model generated in the communication device 1 based on a reference signal with known characteristics among the transmission signals received by the receiving unit 11.

[0029] Fig. 3 is a diagram showing an overview of the compensation models stored in the storage unit 13. The storage unit 13 stores a plurality of compensation models in association with back-off change amounts. Fig. 3 shows that compensation models that differ in 1 dB increments from +5 dB to -5 dB in back-off change amounts are stored. Each compensation model is assigned a model ID for identifying the compensation model.

[0030] When the communication device 1 communicates with a plurality of transmitting devices, it is assumed that the distortion occurring in the transmission signal varies depending on the transmitting device. Therefore, the storage unit 13 may store different compensation models in association with the transmitting devices.

[0031] The control unit 14 includes, for example, a CPU (Central Processing Unit) or a DSP (Digital Signal Processor). The control unit 14 executes a program stored in the storage unit 13 to function as a compensation unit 141, a received signal processing unit 142, a transmission signal generation unit 143, and a back-off control unit 144.

[0032] The compensation unit 141 compensates for distortion in the transmission signal using a compensation model that is determined based on the back-off change amount notified from the transmission device and that is used in processing to compensate for distortion in the transmission signal transmitted from the transmission device. The compensation unit 141 inputs the transmission signal to the compensation model, and inputs the transmission signal after distortion compensation in the compensation model to the received signal processing unit 142.

[0033] Compensation unit 141 determines the compensation model stored in storage unit 13 in association with the back-off change amount notified by the transmitting device as the compensation model to be used in the process of compensating for distortion of the transmission signal. For example, when notified by the transmitting device that the back-off amount has changed, compensator 141 switches from the compensation model that has been used up until then to the compensation model that corresponds to the notified back-off change amount.

[0034] For example, it is assumed that the compensation unit 141 is initially using a compensation model with a model ID of M6 corresponding to a back-off change amount of 0 dB. In response to receiving a notification that the back-off change amount is −2 dB, the compensation unit 141 switches the compensation model to be used to a compensation model with a model ID of M8.

[0035] The compensation unit 141 may select a compensation model stored in the storage unit 13 in association with the transmitting device that transmitted the transmission signal. This allows the compensation unit 141 to appropriately compensate for distortion in the transmission signal, regardless of differences in the characteristics of the transmitting devices, when the communication device 1 communicates with multiple transmitting devices.

[0036] The received signal processing unit 142 processes the signal after distortion has been compensated for and input from the compensation unit 141. The received signal processing unit 142, for example, outputs a sound based on the signal from a speaker, or displays an image based on the signal on a display.

[0037] When communication device 1 functions as communication device 1A, transmission signal generation unit 143 generates a signal to be transmitted to communication device 1B. Transmission signal generation unit 143 generates, for example, a sound signal or an image signal, and inputs the generated signal to transmission unit 12. Transmission signal generation unit 143 changes the amplitude of the generated signal under the control of back-off control unit 144, thereby changing the back-off amount.

[0038] The backoff control unit 144 controls the transmission signal generation unit 143 to change the backoff amount. As described above, the backoff control unit 144 increases the backoff amount to suppress interference with other communication devices, for example, and decreases the backoff amount when it is better to improve the efficiency of the power amplifier. The backoff control unit 144 causes the transmission unit 12 to transmit the backoff change amount, which is the amount of change from the reference value of the backoff amount.

[0039] [Effects of communication device 1] As described above, the communication device 1 compensates for distortion of the transmission signal using a compensation model determined based on the back-off change amount notified by the transmitting device, thereby enabling the communication device 1 to suppress degradation in the quality of the received signal when the transmitting device performs back-off.

[0040] Second Embodiment Fig. 4 is a diagram showing the configuration of a communication device 10 according to the second embodiment. The communication device 10 differs from the communication device 1 shown in Fig. 2 in that it further includes a model creation unit 145, but is the same in other respects.

[0041] The model creation unit 145 creates the compensation model described in the first embodiment. For example, when a transmission signal received by the receiving unit 11 and a back-off change amount are input, the model creation unit 145 creates a compensation model corresponding to the received signal. When a reference signal, which is a transmission signal with known characteristics, and a back-off change amount are input, the model creation unit 145 creates a compensation model corresponding to the back-off change amount notified from the communication device based on the reference signal. The model creation unit 145 associates the created compensation model with the back-off change amount and stores it in the storage unit 13.

[0042] FIG. 5 is a diagram schematically illustrating the operation of model creation unit 145. In FIG. 5, a power amplifier included in communication device 1A distorts reference signal a, resulting in reference signal a'. Model creation unit 145 creates a compensation model that can bring input reference signal a' closer to the original reference signal a. That is, model creation unit 145 creates a compensation model that can reduce the difference between the reference signal and a distortion-free reference signal. Model creation unit 145 sets the created compensation model as a compensation model corresponding to the back-off change amount notified by the transmitting device.

[0043] The model creation unit 145 creates multiple compensation models by adjusting various parameters of the base compensation model, and may select one of the created compensation models that has relatively good signal quality after the compensation unit 141 compensates for the reference signal as the compensation model corresponding to the back-off change amount notified by the transmitting device.

[0044] Model creation unit 145 may update the compensation model to minimize the difference between the reference signal and the received reference signal every time receiver 11 receives a reference signal. By updating the compensation model in this way, model creation unit 145 can suppress the influence of distortion even if the characteristics of the transmitting device or the radio wave propagation environment change.

[0045] <Third embodiment> 6 is a diagram showing the configuration of a communication system S2 according to the third embodiment. In the communication device 10 according to the second embodiment, the model creation unit 145 creates a compensation model corresponding to the back-off change amount received by the receiving unit 11, but the communication device 10 according to the third embodiment differs in that the receiving unit 11 does not receive the back-off change amount, but instead receives back-off change information indicating that the back-off amount has changed.

[0046] The communication device 10 according to the third embodiment differs from the model creation unit 145 according to the second embodiment in that, when back-off change information is received, the model creation unit 145 adaptively re-learns based on the received reference signal and updates the compensation model. The operations of the units other than the model creation unit 145 in the communication device 10 are the same as the operations of the units in the first and second embodiments.

[0047] In the third embodiment, the receiving unit 11 receives backoff change information indicating that the backoff amount in the transmitting device has changed, and a transmission signal transmitted by the transmitting device. When the receiving unit 11 receives the backoff change information, the model creating unit 145 creates a compensation model corresponding to a reference signal, which is a transmission signal with known characteristics. Specifically, as in the second embodiment, the model creating unit 145 creates the compensation model by adjusting various parameters of the base compensation model so as to reduce the difference between the base reference signal and the received reference signal.

[0048] When the receiving unit 11 receives back-off change information, the compensating unit 141 may start the operation of the model creating unit 145, and may stop the operation of the model creating unit to create the compensation model after the model creating unit 145 creates the compensation model. By operating the compensating unit 141 in this manner, it is possible to prevent an increase in power consumption caused by the model creating unit 145 continuing to update the compensation model even when the back-off amount has not changed.

[0049] Fig. 7 is a flowchart showing the flow of processing in the communication device 10. The flowchart shown in Fig. 7 starts from a state in which the communication device 10 receives a transmission signal from the communication device 1A.

[0050] The compensating unit 141 monitors whether or not there has been a change in the backoff amount during communication with the communication device 1A (S1). Specifically, the compensating unit 141 determines whether or not the receiving unit 11 has received backoff change information indicating that the backoff amount has changed. If the compensating unit 141 determines that there has been no change in the backoff amount (NO in S1), the process proceeds to S6, and the compensation unit 141 continues receiving the transmission signal.

[0051] When the compensation unit 141 determines that the backoff amount has changed (YES in S1), it acquires the reference signal received by the receiver 11 (S2) and determines whether the reference signal satisfies a predetermined condition (S3). The predetermined condition is that the communication quality is at or above a reference level, such as that the difference between the reference signal and a standard reference signal is equal to or less than a predetermined value, that the SNR of the reference signal is equal to or greater than a predetermined value, or that the bit error rate of the reference signal is equal to or less than a predetermined value.

[0052] If the reference signal does not satisfy the predetermined condition (NO in S3), the compensation unit 141 updates the parameters of the compensation model stored in the storage unit 13 so as to reduce the difference between the reference signal and the standard reference signal (S4). After re-learning and updating the parameters of the compensation model, the compensation unit 141 again determines whether the reference signal satisfies the predetermined condition (S3).

[0053] If the compensation unit 141 determines that the reference signal satisfies the predetermined condition (YES in S3), it ends the relearning (S5) and receives the transmission signal (S6). The compensation unit 141 repeats the processes from S1 to S6 until the communication ends (NO in S7).

[0054] [Effects of the communication device 10 of the third embodiment] As described above, in the communication device 10 of the third embodiment, when the receiving unit 11 receives a notification that the back-off amount has changed, the model creating unit 145 adaptively updates the compensation model based on the state of the reference signal received by the receiving unit 11. By operating the model creating unit 145 in this manner, the communication device 1 can remove nonlinear distortion from the received transmission signal even when the transmitting device does not transmit the back-off change amount.

[0055] The present invention has been described above using embodiments, but the technical scope of the present invention is not limited to the scope described in the above embodiments, and various modifications and changes are possible within the scope of the gist of the present invention. For example, all or part of the device can be configured by functionally or physically distributing or integrating any unit. Furthermore, new embodiments resulting from any combination of multiple embodiments are also included in the embodiments of the present invention. The effects of the new embodiments resulting from the combination also have the effects of the original embodiments.

[0056] For example, in the above description, the case where communication device 1 and communication device 10 have compensation unit 141 and back-off control unit 144 has been exemplified, but communication device 1 and communication device 10 may have only one of compensation unit 141 and back-off control unit 144. Specifically, if communication device 1 or communication device 10 is, for example, a base station device, communication device 1 or communication device 10 may have back-off control unit 144 but not compensation unit 141. On the other hand, if communication device 1 or communication device 10 is a terminal that communicates with a base station device that can change the back-off amount, communication device 1 or communication device 10 may have compensation unit 141 but not back-off control unit 144.

[0057] In the above explanation, the back-off variation is a value indicating the difference from the reference value of the back-off amount, but the back-off variation may be a value indicating the absolute value of the back-off amount.

[0058] Furthermore, this invention will make it possible to contribute to Goal 9 of the United Nations' Sustainable Development Goals (SDGs), which is "Build resilient infrastructure, promote inclusive and sustainable industrialization, and promote innovation and resilience." [Explanation of symbols]

[0059] 1. Communications equipment 1A Communication equipment 1B Communication equipment 10. Communications equipment 11 Receiving unit 12 Transmitter 13 Storage section 14 Control Unit 141 Compensation Department 142 Received signal processing section 143 Transmission signal generator 144 Back-off control section 145 Model Creation Department

Claims

1. a receiving unit that receives, from the transmitting device, a backoff change amount indicating an amount by which the backoff amount in the transmitting device has changed from a reference value and a transmission signal transmitted by the transmitting device; a compensation unit that compensates for distortion of the transmission signal using a compensation model that is determined based on the back-off change amount and is used in processing to compensate for distortion of the transmission signal transmitted from the transmitting device; A communication device having:

2. a storage unit that stores a plurality of the compensation models in association with back-off variation amounts; the compensator determines the compensation model stored in the storage unit in association with the back-off variation received by the receiver as the compensation model to be used in processing to compensate for distortion of the transmission signal. The communication device according to claim 1 .

3. a model creation unit that, when a reference signal, which is the transmission signal received by the receiving unit and has known characteristics, and a back-off variation amount are input, creates the compensation model corresponding to the back-off variation amount based on the reference signal; The communication device according to claim 1 .

4. the model creation unit creates the compensation model capable of reducing a difference between a standard reference signal in a state where no distortion occurs and the reference signal. The communication device according to claim 3 .

5. the model creation unit creates a plurality of the compensation models, and determines one of the created compensation models, which has a relatively good signal quality after the compensation unit compensates for the reference signal, as the compensation model corresponding to the back-off change amount. The communication device according to claim 3 .

6. a receiving unit that receives backoff change information indicating that a backoff amount in a transmitting device has changed and a transmission signal transmitted by the transmitting device; a model creation unit that, when the receiving unit receives the back-off change information, creates a compensation model to be used in a process of compensating for distortion of the transmission signal transmitted from the transmitting device based on a reference signal that is the transmission signal having known characteristics; and a compensation unit that compensates for distortion of the transmission signal using the compensation model created by the model creation unit; A communication device having:

7. the compensation unit causes the model creation unit to start an operation of creating the compensation model when the receiving unit receives the back-off change information, and after the model creation unit creates the compensation model, causes the model creation unit to stop the operation of creating the compensation model. The communication device according to claim 6.

8. a transmitting device and a receiving device that receives a transmission signal transmitted by the transmitting device, The transmitting device a backoff control unit that changes the backoff amount; a transmitter that transmits the transmission signal and a backoff variation amount, which is a variation amount of the backoff amount from a reference value; and The receiving device a receiving unit that receives the back-off variation amount and the transmission signal; a compensation unit that compensates for distortion of the transmission signal using a compensation model that is determined based on the back-off change amount and is used in processing to compensate for distortion of the transmission signal transmitted from the transmitting device; A communication system having:

9. a transmitting device and a receiving device that receives a transmission signal transmitted by the transmitting device, The transmitting device a backoff control unit that changes the backoff amount; a transmitter that transmits backoff change information indicating that the backoff amount has changed and the transmission signal; and The receiving device a receiving unit that receives the backoff change information and the transmission signal; a model creation unit that, when the receiving unit receives the back-off change information, creates a compensation model to be used in a process of compensating for distortion of the transmission signal transmitted from the transmitting device based on a reference signal that is the transmission signal having known characteristics; and a compensation unit that compensates for distortion of the transmission signal using the compensation model created by the model creation unit; A communication system having:

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