WO2012074041A1 - 通信装置及び通信方法 - Google Patents
通信装置及び通信方法 Download PDFInfo
- Publication number
- WO2012074041A1 WO2012074041A1 PCT/JP2011/077775 JP2011077775W WO2012074041A1 WO 2012074041 A1 WO2012074041 A1 WO 2012074041A1 JP 2011077775 W JP2011077775 W JP 2011077775W WO 2012074041 A1 WO2012074041 A1 WO 2012074041A1
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- transmission power
- transmission
- modulation
- power control
- modulation scheme
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L1/00—Arrangements for detecting or preventing errors in the information received
- H04L1/0001—Systems modifying transmission characteristics according to link quality, e.g. power backoff
- H04L1/0002—Systems modifying transmission characteristics according to link quality, e.g. power backoff by adapting the transmission rate
- H04L1/0003—Systems modifying transmission characteristics according to link quality, e.g. power backoff by adapting the transmission rate by switching between different modulation schemes
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W52/00—Power management, e.g. TPC [Transmission Power Control], power saving or power classes
- H04W52/04—TPC
- H04W52/18—TPC being performed according to specific parameters
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/0008—Modulated-carrier systems arrangements for allowing a transmitter or receiver to use more than one type of modulation
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/18—Phase-modulated carrier systems, i.e. using phase-shift keying
- H04L27/20—Modulator circuits; Transmitter circuits
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/32—Carrier systems characterised by combinations of two or more of the types covered by groups H04L27/02, H04L27/10, H04L27/18 or H04L27/26
- H04L27/34—Amplitude- and phase-modulated carrier systems, e.g. quadrature-amplitude modulated carrier systems
- H04L27/36—Modulator circuits; Transmitter circuits
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W52/00—Power management, e.g. TPC [Transmission Power Control], power saving or power classes
- H04W52/04—TPC
- H04W52/18—TPC being performed according to specific parameters
- H04W52/26—TPC being performed according to specific parameters using transmission rate or quality of service QoS [Quality of Service]
- H04W52/262—TPC being performed according to specific parameters using transmission rate or quality of service QoS [Quality of Service] taking into account adaptive modulation and coding [AMC] scheme
Definitions
- the present invention relates to a technique for changing a modulation scheme according to an adaptive modulation scheme.
- Patent Literature 1 discloses a communication method in a wireless communication system having a transmission-side communication device and a reception-side communication device, and the transmission-side communication device transmits a transmission signal based on the modulation multilevel number. Describes a communication technique characterized by controlling the transmission power of the receiver. In recent years, higher quality communication has been demanded, and realization of wireless communication that does not cause errors in a very short time is required.
- a high multi-level modulation system generally has low resistance to signal distortion, and therefore it is necessary to set the maximum transmission power low so as not to cause a bit error. Therefore, when changing the modulation scheme, if the maximum transmission power in the modulation scheme with a low multi-level number is set and the modulation scheme is changed to a high multi-level number, the transmission power causes a bit error in the modulation scheme. The maximum transmission power that cannot be generated may be exceeded. Under such conditions, a bit error is likely to occur due to distortion generated in the modulated wave after power amplification.
- an object of the present invention is to provide a technique for reducing a bit error due to distortion generated in a modulated wave when the modulation scheme is changed in a direction in which the modulation multilevel number increases.
- One embodiment of the present invention is a communication apparatus that performs wireless communication according to an adaptive modulation scheme, and that modulates data to be transmitted and generates a transmission signal; and transmission power that controls transmission power of the transmission signal And when the modulation multilevel number increases in accordance with an adaptive modulation scheme, the transmission power control unit controls the transmission power before the modulator increases the modulation multilevel number.
- One aspect of the present invention is a communication method for performing wireless communication according to an adaptive modulation method, a modulation step for modulating transmission data and generating a transmission signal, and transmission power for controlling transmission power of the transmission signal And when the modulation multilevel number increases in accordance with the adaptive modulation scheme, before the modulation multilevel number increases in the modulation step, the transmission power control step Control begins.
- the present invention it is possible to reduce bit errors due to distortion generated in a modulated wave when the modulation method is changed in the direction in which the modulation multi-level number increases.
- FIG. 1 is a system configuration diagram showing a system configuration of the communication system 1.
- the communication system 1 includes a plurality of communication devices 100 facing each other.
- a fixed type communication device 100 using wireless communication such as microwaves is shown.
- the configuration of the communication system 1 illustrated in FIG. 1 is merely an example.
- one communication device 100 may be a mobile phone or a wireless LAN terminal device, or the other communication device 100 may be a mobile phone base station or a wireless LAN base station.
- Each communication device 100 includes an IDU (Indoor Unit) 10 and an ODU (Outdoor Unit) 20.
- the ODU 20 includes an antenna that transmits and receives radio waves.
- the communication device 100 performs wireless communication by transmitting and receiving radio waves from an antenna.
- Each antenna may transmit and receive using, for example, a directional microwave as a carrier wave. When using a microwave as a carrier wave, the antennas are installed to face each other. Each antenna may transmit and receive a radio wave with low directivity. In this case, the antennas do not need to be installed so as to face each other.
- FIG. 2 is a diagram illustrating functional blocks of the communication device 100.
- the IDU 10 includes a transmission baseband processing unit 11, a modulator 12, a demodulator 13, a reception baseband processing unit 14, and a reception modulation scheme determination unit 15.
- the ODU 20 includes a variable attenuator 21, an amplifier 22, an antenna 23, a transmission power control unit 24, and a reception power control unit 25.
- the transmission baseband processing unit 11 receives input of data (input data S1) to be transmitted.
- the input data S1 may be data generated in the communication device 100, or may be data input from another device connected to the communication device 100.
- the transmission baseband processing unit 11 multiplexes the determination modulation method information notified from the reception modulation method determination unit 15 and the IDU transmission modulation method control information S4 notified from the transmission power control unit 24 with respect to the input data.
- the determination modulation method information notified from the reception modulation method determination unit 15 is information indicating a modulation method used in downlink communication (hereinafter referred to as “downlink modulation method information”).
- the IDU transmission modulation scheme control information notified from the transmission power control unit 24 is information indicating a modulation scheme used in uplink communication (hereinafter referred to as “uplink modulation scheme information”).
- uplink modulation scheme information information indicating a modulation scheme used in uplink communication
- the transmission baseband processing unit 11 sends data obtained by multiplexing determination modulation scheme information and IDU transmission modulation scheme control information to input data (hereinafter referred to as “transmission radio frame data S2”) to the modulator 12. .
- the modulator 12 reads IDU transmission modulation scheme control information from the transmission radio frame data. Further, the modulator 12 modulates the transmission radio frame data with a modulation scheme according to the read IDU transmission modulation scheme control information, and generates a transmission signal S3. The modulator 12 sends the generated signal to the variable attenuator 21.
- the variable attenuator 21 changes the transmission power according to the control by the transmission power control unit 24.
- the variable attenuator 21 only needs to be able to change the transmission power. For example, the transmission power may be changed by changing the voltage level, or the transmission power may be changed by changing the current value. Also good. In the following description, the variable attenuator 21 attenuates the voltage level of the transmission signal input to the amplifier 22 according to control by the transmission power control unit 24.
- the transmission power control unit 24 controls the transmission power by controlling the variable attenuator 21 according to the ODU transmission modulation scheme control information S5 notified from the reception baseband processing unit 14.
- the transmission power control unit 24 stores a preset attenuation rate table.
- the transmission power control unit 24 determines an attenuation rate according to the modulation method of the ODU transmission modulation method control information notified from the reception baseband processing unit 14 based on the attenuation rate table. Then, the transmission power control unit 24 controls the variable attenuator 21 so that the determined attenuation rate is obtained. Further, the transmission power control unit 24 notifies the transmission baseband processing unit 11 of the ODU transmission modulation scheme control information notified from the reception baseband processing unit 14 as IDU transmission modulation scheme control information.
- the timing at which the transmission power control unit 24 changes the attenuation rate of the variable attenuator 21 and the timing at which the modulation scheme of the IDU transmission modulation scheme control information is changed vary according to the change in the modulation multi-level number.
- the modulation multi-level number of the newly notified ODU transmission modulation scheme control information is larger than the modulation multi-level number of the ODU transmission modulation scheme control information that has been notified up to that point (hereinafter referred to as “multi-level number”).
- the transmission power control unit 24 first starts changing the attenuation factor of the variable attenuator 21 and then changes the modulation method of the IDU transmission modulation method control information.
- the modulation multi-level number in the newly notified ODU transmission modulation scheme control information is smaller than the modulation multi-level number of the ODU transmission modulation scheme control information that has been notified up to that point (hereinafter referred to as “multi-level”).
- the transmission power control unit 24 changes the modulation scheme of the IDU transmission modulation scheme control information, and then starts changing the attenuation factor of the variable attenuator 21.
- the amplifier 22 is an amplifier with a fixed amplification factor.
- the amplifier 22 amplifies the voltage level of the transmission signal attenuated by the variable attenuator 21 with a predetermined amplification factor.
- the antenna 23 sends the signal amplified by the amplifier 22 into the air as a radio wave. Further, the antenna 23 receives a signal transmitted from another communication apparatus 100. In the following description, a signal received by the antenna 23 is referred to as a “received signal”.
- a signal (reception signal) received by the antenna 23 is input to the reception power control unit 25.
- the reception power control unit 25 controls the voltage level of the reception signal to a predetermined voltage level.
- the reception signal whose voltage level is controlled by the reception power control unit 25 is input to the demodulator 13.
- the demodulator 13 demodulates the reception signal S9 by the modulation scheme according to the reception modulation scheme control information notified from the reception baseband processing unit 14, and generates reception radio frame data S10.
- the demodulator 13 sends the generated reception radio frame data to the reception baseband processing unit 14.
- the reception radio frame data generated by the demodulator 13 is the same data as the transmission radio frame data generated by the transmission baseband processing unit 11 of the transmission source communication device 100 if no error has occurred.
- the demodulator 13 generates CNR information (received CNR information) for the received signal.
- the CNR information is information related to the CNR (Carrier vs. Noise Ratio) of the received signal.
- the demodulator 13 notifies the reception modulation scheme determination unit 15 of the generated reception CNR information.
- the reception baseband processing unit 14 extracts data that is a transmission target in the transmission source communication device 100 from the reception radio frame data. Then, the reception baseband processing unit 14 outputs the extracted data (output data S11).
- the data output destination may be an information processing function included in the communication device 100 or may be another information processing device connected to the communication device 100. Further, the reception baseband processing unit 14 extracts reception modulation method information from the reception radio frame data. This reception modulation method information is IDU transmission modulation method control information multiplexed in the signal transmission source communication device 100 and is information representing the modulation method used by the modulator 12 of the transmission source communication device 100.
- the reception baseband processing unit 14 notifies the extracted reception modulation scheme control information S6 to the demodulator 13 and the reception modulation scheme determination unit 15.
- the reception baseband processing unit 14 extracts determination modulation scheme information from the reception radio frame data.
- This determination modulation method information is determination modulation method information S7 multiplexed in the signal transmission source communication apparatus 100, and is information representing the modulation method determined by the transmission modulation method determination unit 15 of the transmission source.
- the reception baseband processing unit 14 notifies the transmission power control unit 24 of the extracted determination modulation scheme information as ODU transmission modulation scheme control information.
- the reception modulation scheme determination unit 15 determines a modulation scheme to be used for downlink communication based on the reception CNR information S8 notified from the demodulator 13. Then, the reception modulation method determination unit 15 notifies the transmission baseband processing unit 11 of the determination result as determination modulation method information.
- FIG. 3 is a diagram illustrating a specific example of the attenuation rate table.
- the attenuation rate table is a table in which the modulation method and the attenuation rate are associated one to one.
- the modulation method of the attenuation rate table corresponds to the modulation method represented by the ODU transmission modulation method control information notified from the reception baseband processing unit 14.
- the attenuation rate in the attenuation rate table represents the attenuation rate at which the variable attenuator 21 is controlled. For example, when the notified ODU transmission modulation scheme control information is QPSK, the transmission power control unit 24 controls the variable attenuator 21 so that the attenuation factor is x1.
- FIG. 4A to 4E are diagrams showing the processing timing of the transmission power control unit 24 when the multi-value number increases.
- FIG. 4A represents a time change of the voltage level of the transmission signal output from the amplifier 22.
- the vertical axis represents the voltage level of the transmission signal, and the horizontal axis represents time.
- FIG. 4B shows a change in the modulation scheme represented by the ODU transmission modulation scheme control information.
- FIG. 4C shows a change in the modulation scheme represented by the ODU internal modulation scheme control information.
- FIG. 4D shows a change in the modulation scheme represented by the IDU transmission modulation scheme control information.
- FIG. 4A represents a time change of the voltage level of the transmission signal output from the amplifier 22.
- the vertical axis represents the voltage level of the transmission signal, and the horizontal axis represents time.
- FIG. 4B shows a change in the modulation scheme represented by the ODU transmission modulation scheme control information.
- FIG. 4C shows a change in the modulation scheme represented by
- 4E shows a temporal change in the content of transmission radio frame data input to the modulator 12 and a modulation scheme of modulation processing performed on the transmission radio frame data by the modulator 12.
- FU indicates a radio frame unit (several ⁇ s).
- 4A to 4E all represent the same time axis.
- the ODU internal modulation scheme control information is control information used by the transmission power control unit 24 to control its own processing timing, and is information representing a modulation scheme corresponding to the transmission power controlled at that time. For example, when the ODU internal modulation scheme control information is QPSK, the transmission power control unit 24 performs control so that the transmission power becomes power according to QPSK.
- the transmission power control unit 24 increases the modulation multi-level number. Judge whether it has been reduced or decreased. In this case, the transmission power control unit 24 determines that the modulation multilevel number has increased. Therefore, the transmission power control unit 24 starts the control of the variable attenuator 21 in advance, and then changes the modulation scheme of the IDU transmission modulation scheme control information. That is, first, at time T11, the transmission power control unit 24 changes the ODU internal modulation scheme control information to the same value as the ODU transmission modulation scheme control information.
- the transmission power control unit 24 changes the ODU internal modulation scheme control information from QPSK to 16QAM.
- the transmission power control unit 24 starts control to change the attenuation rate of the variable attenuator 21 based on the ODU internal modulation scheme control information.
- the transmission power control unit 24 determines to change the attenuation rate to x2 by referring to the attenuation rate table. Then, the transmission power control unit 24 changes the IDU transmission modulation scheme control information notified to the transmission baseband processing unit 11 from QPSK to 16QAM at time T12 after performing the control process on the variable attenuator 21. .
- the timing T12 when the transmission power control unit 24 changes the IDU transmission modulation scheme control information to a new modulation scheme may be determined as follows.
- the transmission power control unit 24 may store in advance the time (t1) required until the voltage level of the transmission signal output from the variable attenuator 21 converges to the value after control.
- the length of the time t1 may be set as appropriate according to the performance of the communication device 100, and may be several milliseconds or several tens of milliseconds, for example.
- the transmission power control unit 24 changes the IDU transmission modulation scheme control information to a new modulation scheme after the elapse of time t1 from the start of control of the attenuation rate of the variable attenuator 21.
- the timing T12 may be determined as follows.
- the transmission power control unit 24 measures the voltage level of the transmission signal output from the variable attenuator 21, and determines whether or not the voltage level of the transmission signal output from the variable attenuator 21 has converged to a value after control. judge.
- the transmission power control part 24 changes the modulation system of IDU transmission modulation system control information, when it determines with the voltage level having converged to the value after control.
- the timing T12 may be mounted so as to be different from the above two specific examples as long as the time has elapsed after the time T11. For example, even if the voltage level does not converge to the value after control, the time required to reach a voltage level at which the influence of signal distortion can be ignored may be set as t1. Further, the transmission power control unit 24 may determine whether or not such a voltage level has been reached. Further, the mounting may be performed by other methods.
- the transmission baseband processing unit 11 changes the modulation method multiplexed in the transmission radio frame data accordingly. (Subsequent timing T13).
- the modulator 12 starts modulation from the timing T14 for modulating the next radio frame according to the changed modulation scheme (16QAM).
- FIG. 5A to 5E are diagrams showing the processing timing of the transmission power control unit 24 when the multi-value number is decreased.
- FIG. 5A represents a time change of the voltage level of the transmission signal output from the amplifier 22.
- the vertical axis represents the voltage level of the transmission signal, and the horizontal axis represents time.
- FIG. 5B shows a change in the modulation scheme represented by the ODU transmission modulation scheme control information.
- FIG. 5C shows a change in the modulation scheme represented by the ODU internal modulation scheme control information.
- FIG. 5D shows a change in the modulation scheme represented by the IDU transmission modulation scheme control information.
- FIG. 5A represents a time change of the voltage level of the transmission signal output from the amplifier 22.
- the vertical axis represents the voltage level of the transmission signal, and the horizontal axis represents time.
- FIG. 5B shows a change in the modulation scheme represented by the ODU transmission modulation scheme control information.
- FIG. 5C shows a change in the modulation scheme represented
- FIGS. 5A to 5E shows the time change of the content of the transmission radio frame data input to the modulator 12 and the modulation method of the modulation process performed on the transmission radio frame data by the modulator 12.
- FU indicates a radio frame unit (several ⁇ s).
- the horizontal axes in FIGS. 5A to 5E all represent the same time axis.
- the modulation scheme represented by the ODU transmission modulation scheme control information changes from 16QAM to QPSK, and the transmission power control unit 24 determines whether the modulation multilevel number has increased or decreased. In this case, the transmission power control unit 24 determines that the modulation multilevel number has decreased. Therefore, the transmission power control unit 24 changes the modulation method of the IDU transmission modulation method control information, and then starts control of the variable attenuator 21. That is, at time T21, the transmission power control unit 24 first changes the IDU transmission modulation scheme control information notified to the transmission baseband processing unit 11 from 16QAM to QPSK.
- the transmission baseband processing unit 11 changes the modulation method multiplexed in the transmission radio frame data accordingly.
- the modulator 12 starts modulation from the timing T22 for modulating the next radio frame in accordance with the changed modulation scheme (QPSK).
- the transmission power control unit 24 changes the ODU internal modulation scheme control information to the same value as the ODU transmission modulation scheme control information. That is, the transmission power control unit 24 changes the ODU internal modulation scheme control information from 16QAM to QPSK.
- the transmission power control unit 24 starts control to change the attenuation rate of the variable attenuator 21 based on the ODU internal modulation scheme control information.
- the transmission power control unit 24 determines to change the attenuation rate to x1 by referring to the attenuation rate table. Thereafter, at timing T24, the voltage level of the transmission signal output from the variable attenuator 21 converges, and the voltage level of the transmission signal output from the amplifier 22 converges to 25 dBm.
- the multilevel modulation method is more susceptible to distortion, so the voltage level of the transmission signal needs to be lowered. Therefore, it is possible to realize wireless communication with few bit errors due to distortion by performing control to lower the voltage level of the transmission signal when the multi-value number increases.
- the modulation method is switched before the control for lowering the voltage level, a bit error due to distortion may occur until the voltage level is lowered.
- Such a problem is not limited to digital microwave communication, but is a problem common to wireless communication.
- the communication apparatus 100 starts control of the voltage level of the transmission signal as shown in FIGS. 4A to 4E, and then changes the modulation method. Therefore, it is possible to reduce bit errors due to distortion generated in the transmission signal.
- the modulation method changes to a modulation method that is more resistant to distortion, so that it is less necessary to start voltage level control before changing the modulation method as described above. Rather, by starting the voltage level control first and then changing the modulation method, it takes a long time to complete the change of the modulation method. For this reason, there arises a problem that it is impossible to follow the sudden deterioration of the received electric field.
- the communication apparatus 100 controls the voltage level of the transmission signal and changes the modulation method almost simultaneously as shown in FIGS. 5A to 5E. For this reason, the time required to complete the change of the modulation method can be shortened compared to when the number of multi-values is increased, and it is possible to follow a sudden deterioration of the received electric field.
- the transmission power control unit 24 controls the voltage level of the transmission signal transmitted from the antenna 23 by controlling the variable attenuator 21.
- the amplifier 22 is not controlled but the attenuator 21 arranged in the preceding stage is controlled, the time required for the control can be further shortened.
- the information that the demodulator 13 notifies to the reception modulation scheme determination unit 15 is not necessarily limited to information related to CNR as long as it is information indicating the communication quality of downlink communication. For example, it may be information regarding the voltage level of the received signal.
- the transmission power control unit 24 may control the voltage level of the transmission signal by controlling the amplification factor of the amplifier 22 instead of controlling the attenuation factor of the variable attenuator 21.
- the amplifier 22 is configured as a variable amplifier having a variable amplification factor.
- the variable attenuator 21 may be configured as an attenuator with a fixed attenuation rate.
- the transmission power control unit 24 may control the voltage level of the transmission signal by controlling both the variable attenuator 21 and the amplifier 22.
- the transmission power control unit 24 may store an attenuated voltage level table instead of the attenuation rate table.
- the post-attenuation voltage level table represents the voltage level of the transmission signal after being attenuated by the variable attenuator 21 for each modulation method. In this case, the transmission power control unit 24 controls the variable attenuator 21 so that the voltage level of the transmission signal output from the variable attenuator 21 becomes the voltage level indicated in the post-attenuation voltage level table.
- the transmission power control unit 24 may store a transmission voltage level table instead of the attenuation rate table.
- the transmission voltage level table represents the voltage level of the transmission signal after being amplified by the amplifier 22 for each modulation method. In this case, the transmission power control unit 24 controls the variable attenuator 21 so that the voltage level of the transmission signal output from the amplifier 22 becomes the voltage level indicated in the transmission voltage level table.
- FIG. 6 is a diagram illustrating a modified example of the configuration of the communication device 100.
- the IDU 10 and the ODU 20 of the communication device 100 may be configured integrally.
- the same reference numerals are used in FIG. 6 for the respective signals and configurations shown in FIG.
- the voltage level of the transmission signal is fixed according to the modulation multi-level number.
- the voltage level of the transmission signal may not be fixed according to the modulation multi-level number.
- the voltage level of the transmission signal may be determined according to ATPC (Automatic Transmitter Power Control).
- the reception baseband processing unit 14 extracts information on the voltage level multiplexed in the reception radio frame data and notifies the transmission power control unit 24 of the information.
- the transmission power control unit 24 controls the attenuation rate of the variable attenuator 21 so that the voltage level of the transmission signal becomes the notified voltage level.
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Abstract
Description
そのため、変調方式を変更する場合、多値数が低い変調方式における最大送信電力が設定された状態で、変調方式が高い多値数に変更されると、送信電力がその変調方式でビット誤りを発生させない最大送信電力を超える可能性がある。そのような条件の下では、電力増幅後の変調波に生じる歪みによってビット誤りが起こりやすくなる。したがって、変調方式を変更するタイミングと送信電力の設定を変更するタイミングを精度良く調整しなければ、それらが前後することにより、ごく短時間でも送信電力が設定されている最大送信電力を超える可能性が出てくる。その場合、ビット誤りを発生させる可能性がある。上記事情に鑑み、本発明は、変調多値数が増加する方向に変調方式を変更する際に、変調波に生じる歪みによるビット誤りを低減する技術を提供することを目的としている。
送信ベースバンド処理部11は、入力データに対し、受信変調方式判定部15から通知される判定変調方式情報と、送信電力制御部24から通知されるIDU送信変調方式制御情報S4を多重化する。受信変調方式判定部15から通知される判定変調方式情報は、下り通信において用いられる変調方式を表す情報(以下、「下り変調方式情報」という。)である。送信電力制御部24から通知されるIDU送信変調方式制御情報は、上り通信において用いられる変調方式を表す情報(以下、「上り変調方式情報」という。)である。送信ベースバンド処理部11は、入力データに対して判定変調方式情報及びIDU送信変調方式制御情報が多重化されたデータ(以下、「送信無線フレームデータS2」という。)を、変調器12に送る。
また、変調器12は、読み出されたIDU送信変調方式制御情報にしたがった変調方式で送信無線フレームデータを変調し、送信信号S3を生成する。変調器12は、生成した信号を可変減衰器21へ送る。
可変減衰器21は、送信電力制御部24による制御にしたがって、送信電力を変更する。可変減衰器21は、送信電力を変更することが可能であれば良く、例えば電圧レベルを変更することによって送信電力を変更しても良いし、電流値を変更することによって送信電力を変更しても良い。以下の説明では、可変減衰器21は、増幅器22に入力される送信信号の電圧レベルを、送信電力制御部24による制御に従って減衰させる。
アンテナ23は、増幅器22によって増幅された信号を電波として空気中に送出する。
また、アンテナ23は、他の通信装置100から送出された信号を受信する。以下の説明において、アンテナ23によって受信された信号を「受信信号」と呼ぶ。アンテナ23によって受信された信号(受信信号)は、受信電力制御部25に入力される。
受信電力制御部25は、受信信号の電圧レベルを制御し、所定の電圧レベルにする。受信電力制御部25によって電圧レベルが制御された受信信号は、復調器13に入力される。
また、復調器13は、受信信号についてのCNR情報(受信CNR情報)を生成する。
CNR情報とは、受信信号のCNR(Carrier vs. Noise Ratio)に関する情報である。
復調器13は、生成した受信CNR情報を受信変調方式判定部15へ通知する。
また、受信ベースバンド処理部14は、受信無線フレームデータから、受信変調方式情報を抽出する。この受信変調方式情報は、信号の送信元の通信装置100において多重化されたIDU送信変調方式制御情報であり、当該送信元の通信装置100の変調器12が用いる変調方式を表す情報である。受信ベースバンド処理部14は、抽出した受信変調方式制御情報S6を復調器13及び受信変調方式判定部15へ通知する。
受信変調方式判定部15は、復調器13から通知された受信CNR情報S8に基づいて、下り通信に用いられるべき変調方式を判定する。そして、受信変調方式判定部15は、判定結果を判定変調方式情報として送信ベースバンド処理部11へ通知する。
減衰率テーブルの減衰率は、可変減衰器21が制御される減衰率を表す。例えば、通知されたODU送信変調方式制御情報がQPSKである場合、送信電力制御部24は、減衰率がx1となるように可変減衰器21を制御する。
このような問題に対し、通信装置100は、図4A~図4Eに示されるように送信信号の電圧レベルの制御を先に開始し、その後に変調方式を変更する。そのため、送信信号に生じる歪みによるビット誤りを低減することが可能となる。
復調器13が受信変調方式判定部15へ通知する情報は、下り通信の通信品質を表す情報であればCNRに関する情報に限定される必要は無い。例えば、受信信号の電圧レベルに関する情報であっても良い。
送信電力制御部24は、可変減衰器21の減衰率を制御するのではなく、増幅器22の増幅率を制御することによって、送信信号の電圧レベルを制御しても良い。この場合、増幅器22は、増幅率が可変の可変増幅器として構成される。また、可変減衰器21は、減衰率が固定された減衰器として構成されても良い。また、送信電力制御部24は、可変減衰器21及び増幅器22の双方を制御することによって、送信信号の電圧レベルを制御しても良い。
送信電力制御部24は、減衰率テーブルに変えて送信電圧レベルテーブルを記憶しても良い。送信電圧レベルテーブルは、増幅器22によって増幅された後の送信信号の電圧レベルを、変調方式毎に表す。この場合、送信電力制御部24は、増幅器22から出力される送信信号の電圧レベルが送信電圧レベルテーブルに示される電圧レベルになるように、可変減衰器21を制御する。
上述した通信装置100では、変調多値数に応じて送信信号の電圧レベルが固定されていた。これに対し、変調多値数に応じて送信信号の電圧レベルが固定されていなくとも良い。例えば、ATPC(Automatic Transmitter Power Control)にしたがって送信信号の電圧レベルが決定されても良い。この場合、受信ベースバンド処理部14は、受信無線フレームデータに多重されている電圧レベルに関する情報を抽出し、送信電力制御部24へ通知する。送信電力制御部24は、送信信号の電圧レベルが、通知された電圧レベルとなるように可変減衰器21の減衰率を制御する。
本願は、2010年12月3日に、日本に出願された特願2010-270078号に基づき優先権を主張し、その内容をここに援用する。
11 送信ベースバンド処理部
12 変調器
13 復調器
14 受信ベースバンド処理部
15 受信変調方式判定部
20 ODU
21 可変減衰器(送信電力変更部)
22 増幅器(送信電力変更部)
23 アンテナ
24 送信電力制御部
25 受信電力制御部
Claims (5)
- 適応変調方式に応じて無線通信を行う通信装置であって、
送信されるデータを変調し送信信号を生成する変調器と、
前記送信信号の送信電力を制御する送信電力制御部と、
を備え、
適応変調方式に応じて変調多値数が増加する場合には、前記変調器が前記変調多値数を増加する前に、前記送信電力制御部が前記送信電力の制御を開始する通信装置。 - 適応変調方式に応じて変調多値数が減少する場合には、前記変調器が前記変調多値数を減少した後に、前記送信電力制御部が前記送信電力の制御を開始する請求項1に記載の通信装置。
- 前記送信信号の送信電力は、前記送信信号の送信電力を減衰させる可変減衰器と、前記可変減衰器によって前記送信電力が減衰された前記送信信号の送信電力を増幅する増幅器と、によって変更され、
前記送信電力制御部は、前記可変減衰器の減衰率を制御することによって、前記送信信号の送信電力を制御する請求項1に記載の通信装置。 - 適応変調方式に応じて無線通信を行う通信方法であって、
送信されるデータを変調し送信信号を生成する変調ステップと、
前記送信信号の送信電力を制御する送信電力制御ステップと、
を有し、
適応変調方式に応じて変調多値数が増加する場合には、前記変調ステップにおいて前記変調多値数が増加する前に、前記送信電力制御ステップにおいて前記送信電力制御ステップが開始される通信方法。 - 適応変調方式に応じて変調多値数が減少する場合には、前記変調ステップにおいて前記変調多値が減少した後に、前記送信電力制御ステップにおいて前記送信電力制御ステップが開始される請求項4に記載の通信方法。
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EP11844343.1A EP2648380A4 (en) | 2010-12-03 | 2011-12-01 | Communication device and communication method |
JP2012546928A JP5590147B2 (ja) | 2010-12-03 | 2011-12-01 | 通信装置及び通信方法 |
US13/988,420 US9936461B2 (en) | 2010-12-03 | 2011-12-01 | Communication device and communication method |
CN201180056456.4A CN103229475B (zh) | 2010-12-03 | 2011-12-01 | 通信设备和通信方法 |
US15/899,552 US10568043B2 (en) | 2010-12-03 | 2018-02-20 | Communication device and communication method |
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EP (1) | EP2648380A4 (ja) |
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CN106455028B (zh) * | 2015-08-07 | 2020-04-14 | 中兴通讯股份有限公司 | 控制下行数据发射功率的方法和装置 |
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US20180249422A1 (en) | 2018-08-30 |
US9936461B2 (en) | 2018-04-03 |
CN106899383A (zh) | 2017-06-27 |
CN103229475A (zh) | 2013-07-31 |
EP2648380A4 (en) | 2017-10-04 |
US20130244717A1 (en) | 2013-09-19 |
JPWO2012074041A1 (ja) | 2014-05-19 |
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EP2648380A1 (en) | 2013-10-09 |
JP5590147B2 (ja) | 2014-09-17 |
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