WO2011065409A1 - 無線通信システム、無線通信装置及び無線通信方法 - Google Patents
無線通信システム、無線通信装置及び無線通信方法 Download PDFInfo
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- WO2011065409A1 WO2011065409A1 PCT/JP2010/070996 JP2010070996W WO2011065409A1 WO 2011065409 A1 WO2011065409 A1 WO 2011065409A1 JP 2010070996 W JP2010070996 W JP 2010070996W WO 2011065409 A1 WO2011065409 A1 WO 2011065409A1
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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
- 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
- H04L1/0023—Systems modifying transmission characteristics according to link quality, e.g. power backoff characterised by the signalling
- H04L1/0025—Transmission of mode-switching indication
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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
- H04L1/0023—Systems modifying transmission characteristics according to link quality, e.g. power backoff characterised by the signalling
- H04L1/0028—Formatting
- H04L1/003—Adaptive formatting arrangements particular to signalling, e.g. variable amount of bits
Definitions
- the present invention relates to a technique for controlling a modulation method in wireless communication.
- an adaptive modulation scheme has been proposed as a technique for coping with changes in the state of a radio propagation path.
- the state of the radio propagation path is determined, and when the state deteriorates, communication is performed with a modulation method with a small modulation multi-level number, and when the state is good, a modulation method with a large modulation multi-level number is used.
- Communicate Specifically, the receiver estimates the state of the radio propagation path from the received signal, determines the modulation scheme, and feeds back the determined modulation scheme to the transmitter.
- the transmitter performs transmission processing by applying the modulation scheme fed back from the receiver.
- Such an adaptive modulation method is widely used in fixed microwave radio transmission apparatuses, mobile communication radio base station apparatuses, and the like.
- the modulation scheme control in the case where the radio line is disconnected has not been sufficiently studied. Therefore, for example, the following problems have occurred. If a radio channel suddenly deteriorates during radio propagation using a modulation scheme with a large modulation multi-level, the radio link will be changed before the adaptive modulation scheme switches to a modulation scheme with a smaller modulation multi-level. Will be cut off. In general, the higher the multi-level modulation method, the higher the reception level is required for the connection of the wireless line. Therefore, when the line is disconnected as described above, a high reception level is required for returning the wireless line. There was a problem that it took time to restore the wireless line.
- an object of the present invention is to provide a technique capable of returning a wireless line in a shorter time when the wireless line is disconnected in wireless communication using an adaptive modulation method. Yes.
- One aspect of the present invention is a wireless communication system including a first wireless communication device and a second wireless communication device that perform wireless communication via a wireless propagation path, and the first wireless communication device includes the second wireless communication device.
- a reception unit that receives a radio signal from a device via the wireless propagation path
- a disconnection detection unit that detects a disconnection of a radio channel between the second radio communication device, and a disconnection of the radio channel are detected
- a modulation scheme control unit that selects a modulation scheme that enables communication in a channel state worse than the modulation scheme that has been used in wireless communication, and the modulation scheme selected by the modulation scheme control unit.
- a wireless communication device that detects a disconnection of a wireless line between a receiving unit that receives a wireless signal from another wireless communication device via a wireless propagation path and the other wireless communication device.
- a detection unit, and a modulation method control unit that selects a modulation method that enables communication in a channel state worse than the modulation method used in the wireless communication up to now when disconnection of the wireless line is detected;
- a transmitting unit that notifies the other wireless communication device in order for the other wireless communication device to apply the modulation method selected by the modulation method control unit when generating a transmission signal for the own device.
- One aspect of the present invention is a wireless communication method performed by a wireless communication system including a first wireless communication device and a second wireless communication device that perform wireless communication via a wireless propagation path, wherein the first wireless communication device A radio signal is received from the second radio communication device via the radio propagation path, the first radio communication device detects a disconnection of a radio line with the second radio communication device, and the first radio communication device When a disconnection of the wireless line is detected, a modulation scheme that enables communication in a channel state worse than the modulation scheme used in the previous wireless communication is selected, and the first wireless communication device Notifying the second wireless communication device of the selected modulation method, the second wireless communication device receiving the selected modulation method from the first wireless communication device, and receiving the second wireless communication device.
- the selected modulation method Zui by and a transmission step for transmitting to the first wireless communication device.
- the wireless line when a wireless line is disconnected, the wireless line can be restored in a shorter time.
- FIG. 1 is a system configuration diagram showing a system configuration of a wireless communication system.
- the wireless communication system includes a plurality of wireless communication devices 1.
- wireless communication devices 1 perform wireless communication based on an adaptive modulation scheme.
- the configuration of the wireless communication system shown in FIG. 1 is merely an example.
- one wireless communication device 1 is configured using a mobile phone or a wireless LAN terminal device, and the other wireless communication device 1 is a mobile phone base station or You may comprise using a wireless LAN base station.
- FIG. 2 is a block diagram showing an outline of a functional configuration of the wireless communication system.
- the wireless communication system includes a wireless communication device 1 and another wireless communication device 1 that is a communication partner of the wireless communication device 1.
- the former wireless communication device 1 is referred to as “own device 1-1”
- the other wireless communication device 1 that is the communication partner of the own device 1-1 is referred to as “opposing wireless communication device 1-2”. .
- the wireless communication device 1 (the own device 1-1 and the opposite wireless communication device 1-2) includes a transmission block 10 and a reception block 20.
- the transmission block 10 includes a transmission unit 11.
- the reception block 20 includes a reception unit 21, a disconnection detection unit 22, a modulation scheme control unit 23, and a radio propagation path estimation unit 24.
- the receiving unit 21 of the own device 1-1 receives a wireless signal from the opposite wireless communication device 1-2 via the wireless propagation path.
- the disconnection detection unit 22 of the own device 1-1 detects the disconnection of the wireless line with the opposing wireless communication device 1-2.
- the modulation method control unit 23 of the own device 1-1 detects the disconnection of the wireless channel with the opposite wireless communication device 1-2 based on the modulation method used in the wireless communication so far.
- a modulation scheme that enables communication in a poor propagation path state is selected.
- the radio propagation path estimation unit 24 of the own apparatus 1-1 estimates the state of the radio propagation path based on the radio signal received by the reception unit 21 of the own apparatus 1-1.
- the transmission unit 11 of the own device 1-1 notifies the opposite wireless communication device 1-2 of the modulation method selected by the modulation method control unit 23.
- the receiving unit 21 of the opposite side wireless communication device 1-2 receives a modulation scheme notification from the transmitting unit 11 of the own device 1-1.
- the transmitting unit 11 of the opposite wireless communication apparatus 1-2 performs transmission to the own apparatus 1-1 based on the modulation scheme received by the receiving unit 21 of the opposite wireless communication apparatus 1-2.
- FIG. 3 is a schematic block diagram illustrating a functional configuration of the wireless communication device 1 according to the first embodiment.
- FIG. 4 is a diagram illustrating an outline of a signal and a radio frame format used in the radio communication apparatus 1. Details of FIG. 4 will be described later.
- the wireless communication device 1 includes a transmission block 10 and a reception block 20.
- the transmission block 10 includes a TX baseband processing unit 101 and a modulation unit 102.
- the reception block 20 includes a demodulation unit 201, a frame synchronization unit 202, a modulation scheme control unit 203, and an RX baseband processing unit 204.
- the TX baseband processing unit 101 and the modulation unit 102 correspond to the transmission unit 11.
- the demodulation unit 201 corresponds to the reception unit 21 and the radio propagation path estimation unit 24.
- the frame synchronization unit 202 corresponds to the disconnection detection unit 22.
- the modulation method control unit 203 corresponds to the modulation method control unit 23.
- the wireless communication device 1 in the first embodiment will be further described.
- the TX baseband processing unit 101 is connected to a wired communication network such as Ethernet (registered trademark) / PDH / SDH, and receives a TX baseband input signal 111 from another communication device in the wired communication network.
- the TX baseband processing unit 101 multiplexes the received TX baseband input signal 111 into the payload unit 401 in the radio frame format.
- the TX baseband processing unit 101 multiplexes the transmission modulation method information signal 219 into the own direction modulation method information unit 412 of the overhead unit 410, and transmits the opposite transfer modulation method information signal 218 to the transfer modulation method information unit of the overhead unit 410.
- the signal is multiplexed to 413.
- the transmission modulation scheme information signal 219 is a signal representing the modulation scheme determined by the modulation scheme control unit 203 of the opposite radio communication apparatus 1-2.
- the opposite transfer modulation method information signal 218 is a signal representing the modulation method determined by the modulation method control unit 203 of the own device 1-1 and should be applied by the modulation unit 102 of the opposite wireless communication device 1-2. It is a signal representing a modulation method.
- the opposite transfer modulation scheme information signal 218 is signal-multiplexed with the TX baseband output signal 112 and transmitted to be notified to the opposite radio communication apparatus 1-2.
- the opposite transfer modulation method information signal 218 is extracted by the RX baseband processing unit 204 of the opposite side wireless communication device 1-2 and is transmitted to the transmission block 10 as a transmission modulation method information signal 219. 2 is used for modulation processing for wireless communication from 2 to its own device 1-1.
- the TX baseband processing circuit 101 further generates a TX baseband output signal 112 by performing scramble processing and error correction coding processing on the payload section 401. Next, the TX baseband processing unit 101 sends the generated TX baseband output signal 112 to the modulation unit 102.
- the modulation unit 102 generates a transmission modulation signal 113 by performing modulation processing on the TX baseband output signal 112 received from the TX baseband processing unit 101.
- the modulation unit 102 extracts the transmission modulation method information signal 219 from the own direction modulation method information unit 412 of the received TX baseband output signal 112, and the modulation specified by the extracted transmission modulation method information signal 219 is performed.
- Modulation processing is performed based on the method. Specifically, the modulation unit 102 performs mapping processing, waveform shaping, nonlinear distortion correction, and modulation processing to an intermediate frequency corresponding to the designated modulation method. Next, the modulation unit 102 performs frequency conversion to a high frequency band and power amplification on the generated transmission modulation signal 113, and then outputs the signal from the antenna to the radio propagation path.
- Radio frame 400 is the minimum unit in the modulation method application section. Therefore, in order to apply the modulation scheme specified by the transmission modulation scheme information signal 219 extracted from the own direction modulation scheme information section 412, the modulation section 102 needs to wait until the next radio frame 400. For example, when the modulation schemes in the previous radio frame 400 and the current radio frame 400 indicate QPSK and 256QAM, respectively, the modulation unit 102 performs modulation processing by QPSK in the current radio frame 400, and performs the next radio frame 400 In the frame 400, modulation processing is performed with 256QAM. It should be noted that the modulation scheme determination and the number of radio frames 400 to be applied are appropriately set according to the environment used by the radio communication apparatus 1.
- the demodulator 201 performs power amplification and frequency conversion to the intermediate frequency band on the received modulation signal 210 received by the antenna from the opposite radio communication apparatus 1-2 via the radio propagation path, and then performs baseband band conversion. Demodulation process is performed.
- the demodulation unit 201 performs demodulation processing according to the modulation method specified by the demodulation processing modulation method information signal 215 received from the frame synchronization unit 202. Specifically, the demodulation unit 201 performs waveform shaping, waveform equalization, carrier synchronization establishment, and demapping processing corresponding to the above modulation scheme. Then, the demodulation unit 201 sends the demodulation circuit output signal 211 generated by the demodulation process to the frame synchronization unit 202.
- the demodulation unit 201 determines reception quality from the reception modulation signal 210 and generates a reception quality determination value signal 214.
- the reception quality judgment value signal 214 is information representing a result of the demodulation unit 201 estimating the state of the wireless propagation path based on a carrier-to-noise ratio (CNR), a reception level, and the like.
- CNR carrier-to-noise ratio
- the demodulator 201 sends the generated reception quality determination value signal 214 to the modulation scheme controller 203.
- the frame synchronization unit 202 generates a frame synchronization circuit output signal 212 by establishing frame synchronization for the demodulation circuit output signal 211 received from the demodulation unit 201.
- the frame synchronization unit 202 sends the generated frame synchronization circuit output signal 212 to the RX baseband processing unit 204.
- the frame synchronization unit 202 extracts the frame pattern from the frame pattern unit 411 in the overhead unit 410 of the demodulation circuit output signal 211 received from the demodulation unit 201.
- the frame synchronization unit 202 collates the known frame pattern with the extracted frame pattern, and determines that frame synchronization is established when the pattern matches continuously a predetermined number of times.
- the frame synchronization unit 202 determines that the frame is asynchronous. When it is determined that the frame is asynchronous, the frame synchronization unit 202 overwrites the modulation scheme information indicated by the radio cutoff modulation scheme information signal 217 on the demodulation modulation scheme information signal 215.
- the determination method for determining that frame synchronization is established or frame asynchronous and the number of frame pattern verifications are appropriately set according to the environment in which the wireless communication apparatus 1 is used.
- the frame synchronization unit 202 After establishing the frame synchronization, the frame synchronization unit 202 sends a frame asynchronous activation signal 216 indicating the frame synchronization determination result to the modulation scheme control unit 203. Further, after establishing frame synchronization, the frame synchronization unit 202 detects the position of the own direction modulation scheme information unit 412 with reference to the head of the radio frame 400. Next, frame synchronization section 202 extracts modulation scheme information from detected self-direction modulation scheme information section 412, and sends it to demodulation section 201 as modulation scheme information signal 215 for demodulation processing.
- the demodulator 201 cannot know the start position of the radio frame 400 and cannot adjust the timing to apply the modulation method notified from the frame synchronization unit 202 by the modulation method information signal 215 for demodulation processing. Therefore, the frame synchronization unit 202 sends the modulation scheme information extracted from the own direction modulation scheme information unit 412 to the demodulation unit 201 at a timing obtained by subtracting the processing delay of the frame synchronization unit 202 from the next radio frame 400. Through such processing, the demodulator 201 can perform demodulation processing on each radio frame 400 using an appropriate modulation scheme.
- the modulation scheme control unit 203 determines a modulation scheme to be employed in the modulation unit 102 of the opposite radio communication apparatus 1-2 based on the reception quality determination value signal 214 and the frame asynchronous activation signal 216. Then, the modulation scheme control unit 203 generates a counter transfer modulation scheme information signal 218 representing the determination result, and sends it to the TX baseband processing circuit 101.
- the modulation scheme control unit 203 receives the frame asynchronous activation signal 216 from the frame synchronization unit 202. When the modulation scheme control unit 203 determines that the radio link with the opposite radio communication apparatus 1-2 has been cut off, the modulation scheme control unit 203 indicates a modulation scheme to be employed when the radio link is cut off. Modulation method information signal 217 is sent to frame synchronization section 202.
- the RX baseband processing unit 204 generates an RX baseband output signal 213 by performing error correction decoding processing and descrambling processing on the payload unit 401 in the frame synchronization circuit output signal 212 received from the frame synchronization unit 202. To do.
- the RX baseband processing unit 204 transmits the generated RX baseband output signal 213 to another communication device in a wired communication network such as Ethernet (registered trademark) / PDH / SDH to which the RX baseband processing unit 204 is connected.
- the RX baseband processing unit 204 extracts modulation scheme information from the transfer modulation scheme information unit 413 in the frame synchronization circuit output signal 212 received from the frame synchronization unit 202. Then, the RX baseband processing unit 204 sends the extracted modulation scheme information to the TX baseband processing circuit 101 as a transmission modulation scheme information signal 219.
- the transmitted transmission modulation method information signal 219 is used for modulation processing in wireless communication from the own device 1-1 to the opposite station side wireless communication device, that is, modulation processing by the modulation unit 102 of the own device 1-1.
- the signal (A) transmitted by the wireless communication device 1 is composed of a plurality of wireless frames 400 arranged in succession.
- the radio frame 400 includes a payload part 401 and an overhead part 410.
- the overhead unit 410 is arranged at the head of the radio frame 400 and has information necessary for frame synchronization establishment and modulation scheme control.
- the overhead unit 410 includes a frame pattern unit 411, a self-direction modulation scheme information unit 412, and a transfer modulation scheme information unit 413.
- the own-direction modulation scheme information unit 412 includes modulation scheme information determined by the opposite radio communication apparatus 1-2, that is, modulation scheme information used for modulation processing for radio communication in the direction in which the radio frame 400 is propagated. Are multiplexed.
- the modulation method information unit for transfer 413 the modulation method information determined by the modulation method control unit 203 of the device 1-1 is multiplexed.
- the wireless communication device 1 controls the modulation method independently by bidirectional communication. Therefore, not only the own direction modulation method information unit 412 but also the transfer modulation method information unit 413 is provided on the radio frame 400. Further, each pattern, data length, and multiplexing order of the overhead unit 410 are appropriately set according to the environment in which the wireless communication apparatus 1 is used. In the payload section 401, mainly propagated information is multiplexed.
- the format of the radio frame 400 shown in FIG. 4 is the minimum unit for switching the modulation method.
- the TX baseband output signal 112, the demodulation circuit output signal 211, and the frame synchronization circuit output signal 212 basically have the overhead portion 410 of FIG.
- FIG. 5 is a diagram illustrating an outline of processing when the modulation scheme control unit 203 determines a modulation scheme.
- the modulation scheme control unit 203 determines the modulation scheme by selecting the modulation multi-value number from a predetermined range.
- the range of the value of the modulation multi-value number that can be selected by the modulation scheme control unit 203 is configured by two ranges, an adaptive modulation range and a break time range.
- the adaptive modulation range is a range between the modulation multi-level number M1 and the modulation multi-level number M2
- the break time range is a range between the modulation multi-level number M2 and the modulation multi-level number M3.
- the minimum modulation multi-level number in the adaptive modulation range and the maximum modulation multi-level number in the interruption range are both the same in M2, but they are not necessarily the same.
- the range and the break range may be set apart from each other.
- the adaptive modulation range is a range composed of a modulation multi-value number that is larger than the maximum modulation multi-value number in the break range, and is selected in the normal adaptive modulation method when the radio line is connected normally. Represents the range of modulation multi-values to be performed.
- the range at the time of disconnection represents the range of the modulation multi-value number selected when the radio line is disconnected and when it is a recovery period after the disconnection.
- the modulation multi-level number included in the disconnection range may be one. In this case, the modulation multi-level number included in the break range is the smallest modulation multi-level number that can be selected by the wireless communication device 1.
- QPSK and 16QAM may be set as the break range
- 32QAM, 64QAM, 128QAM, and 256QAM may be set as the adaptive modulation range.
- the modulation multi-value number of the modulation method set in the break time range and the adaptive modulation range is appropriately set according to the use of the wireless communication apparatus 1 and the wireless propagation environment.
- FIG. 6 is a flowchart showing the processing flow of the modulation scheme control unit 203.
- the modulation scheme control unit 203 receives the frame asynchronous activation signal 216 from the frame synchronization unit 202 (step S101). Based on the received frame asynchronous activation signal 216, the modulation scheme control unit 203 determines whether or not the radio line with the opposite radio communication apparatus 1-2 has been disconnected (step S102). The modulation scheme control unit 203 determines whether or not the radio line is disconnected based on whether or not the value of the frame asynchronous activation signal 216 indicates a frame synchronization state.
- the modulation scheme control unit 203 determines that the wireless line is not disconnected, that is, is normal.
- the modulation scheme control unit 203 determines that the wireless line is disconnected.
- the modulation scheme control unit 203 selects the modulation multi-value number from the disconnection range (step S103). At this time, for example, the modulation scheme control unit 203 selects the smallest modulation multilevel number (M3) in the range at the time of interruption.
- the modulation scheme control unit 203 determines whether or not the modulation multilevel number selected at the previous modulation scheme selection is selected from the adaptive modulation range (Ste S104).
- the modulation scheme control section 203 receives the reception quality judgment value received from the demodulation section 201. Based on the signal 214, a modulation multi-value number is selected from the adaptive modulation range (step S105).
- the modulation method control unit 203 determines that it is the recovery period, and selects the modulation multi-value number from the break range and the adaptive modulation range based on the reception quality judgment value signal 214 received from the demodulator 201 (step S106).
- the wireless communication device 1 determines whether or not the wireless line between the own device 1-1 and the opposite wireless communication device 1-2 is disconnected based on the presence or absence of frame asynchrony. Then, when the disconnection of the wireless line is detected by the own apparatus 1-1, the modulation scheme control unit 203 selects a modulation multi-value number smaller than that in the normal state. For this reason, the state of the communication channel is poor compared to the case where the modulation multi-value number is always selected from a certain range regardless of whether the radio channel is normal or not as in the conventional adaptive modulation system. Even in the state, since it is possible to start communication at a low communication speed, the wireless line can be restored in a shorter time.
- the modulation multi-value number is selected from the adaptive modulation range. For this reason, it is possible to quickly return from disconnection of the radio line as described above while maintaining a high communication speed by suppressing the selection of an unnecessarily small modulation multilevel number.
- the modulation scheme control unit 203 determines the modulation scheme by selecting the modulation multilevel number. However, the modulation scheme control unit 203 determines not only the modulation multilevel number but also other values. It may be configured. For example, the modulation scheme may be determined by selecting a coding rate value from a plurality of values. Also in this case, the cut-off range and the adaptive modulation range are set as the coding rate selection range. In any case, a higher propagation speed is set as the adaptive modulation range, and a stronger resistance is set as the break-off range even when the propagation speed is lower.
- the frame synchronization unit 202 transmits not only the demodulation modulation method information signal 215 but also the transfer modulation method information unit 413 in the overhead unit 410 to the wireless disconnection modulation method information.
- the modulation scheme information indicated by the signal 217 may be overwritten. In this case, even if the bidirectional wireless line is disconnected in a subordinate (simultaneous) manner between the own device 1-1 and the opposite wireless communication device 1-2, the modulation unit 102 of the own device 1-1. In other words, it is possible to apply the modulation scheme information in the disconnection range earlier to the modulation unit 102 that performs transmission from the own device 1-1 to the opposite wireless communication device 1-2.
- FIG. 7 is a block diagram illustrating a functional configuration of the wireless communication device 1 according to the second embodiment.
- the wireless communication device 1 according to the second embodiment will be described with respect to differences from the wireless communication device 1 according to the first embodiment.
- the demodulator 201 in the second embodiment corresponds to the receiver 21, the disconnection detector 22, and the radio propagation path estimator 24.
- the demodulator 201 in the second embodiment performs carrier asynchronous detection and generates a carrier asynchronous signal 220 that represents the detection result. For example, the demodulator 201 sets a value of “High” in the carrier asynchronous signal 220 when carrier asynchronous is detected, and sets “Low” in the carrier asynchronous signal 220 when carrier asynchronous is not detected (that is, in carrier synchronous). Set the value of "”. Then, the demodulator 201 sends the generated carrier asynchronous activation signal 220 to the modulation scheme controller 203.
- the modulation scheme control unit 203 in the second embodiment determines whether or not the radio line between the opposite radio communication device 1-2 is disconnected based on the carrier asynchronous activation signal 220.
- the modulation scheme control unit 203 determines that the radio line is disconnected when the carrier asynchronous activation signal 220 indicates carrier asynchronous.
- the modulation scheme control unit 203 determines that the radio channel is normal when the carrier asynchronous activation signal 220 indicates carrier synchronization.
- step S101 in FIG. 6 is processing for receiving the carrier asynchronous activation signal 220.
- the modulation scheme control unit 203 in the second embodiment receives the carrier asynchronous activation signal 220 representing the carrier asynchronousity
- the modulation scheme information signal 217 at the time of wireless disconnection (the modulation multi-level number selected when the wireless line is disconnected)
- the modulation scheme information indicated by the corresponding modulation scheme information) is set as the opposite transfer modulation scheme information signal 218.
- the modulation scheme control unit 203 sets a value (for example, “High”) indicating that the radio line is disconnected in the radio disconnection modulation scheme control signal 221, and sends it to the frame synchronization unit 202.
- the frame synchronization unit 202 in the second embodiment receives the wireless cutoff modulation scheme control signal 221 in which a value indicating that the wireless line is disconnected is received, the demodulation processing modulation scheme information signal 215 is transmitted to the demodulation processing modulation scheme information signal 215.
- the modulation method information indicated by the information signal 217 is overwritten and transmitted.
- the frame synchronization unit 202 directly uses the carrier asynchronous activation signal 220 as a timing signal for applying the radio interruption modulation scheme information signal 217, instead of using the radio interruption modulation scheme control signal 221. May be.
- the frame synchronization unit 202 when the frame synchronization unit 202 receives the carrier asynchronous activation signal 220 indicating that the wireless line has been disconnected, the frame synchronization unit 202 overwrites the modulation method information indicated by the wireless disconnection modulation method information signal 217 on the demodulation processing modulation method information signal 215. May be configured to be transmitted.
- the disconnection of the wireless line is detected based on carrier asynchrony. Therefore, it is possible to detect the disconnection of the radio line earlier than the radio communication apparatus 1 in the first embodiment that detects the disconnection of the radio line based on the frame asynchrony. Therefore, the process of selecting the modulation multi-value number from the range at the time of disconnection according to the disconnection of the radio line and notifying the opposite radio communication apparatus 1-2 can be performed quickly, and the radio line can be restored early. It becomes possible.
- FIG. 8 is a schematic block diagram illustrating a functional configuration of the wireless communication device 1 according to the third embodiment.
- the difference between the wireless communication device 1 in the third embodiment and the wireless communication device 1 in the first embodiment and the second embodiment will be described.
- the wireless communication device 1 further includes a selection unit 205 in the reception block 20.
- the demodulation unit 201, the frame synchronization unit 202, and the selection unit 205 correspond to the disconnection detection unit 22.
- the demodulator 201 according to the third embodiment performs carrier asynchronous detection and generates a carrier asynchronous signal 220 representing the detection result. For example, the demodulator 201 sets a value of “High” in the carrier asynchronous signal 220 when carrier asynchronous is detected, and sets “Low” to the carrier asynchronous signal 220 when carrier asynchronous is not detected (that is, in carrier synchronous). Set the value of "”.
- Demodulation section 201 then sends generated carrier asynchronous activation signal 220 to selection section 205.
- the frame synchronization unit 202 in the third embodiment performs frame asynchronous detection, and generates a frame asynchronous activation signal 230 representing the detection result. Then, the frame synchronization unit 202 sends the generated frame asynchronous activation signal 230 to the selection unit 205.
- the selection unit 205 determines the disconnection of the radio line according to the frame asynchronous activation signal 230 and the carrier asynchronous activation signal 220 according to a predetermined determination criterion.
- the criterion set in advance in the selection unit 205 is set programmably using parameters, for example. More specifically, for example, setting is made so as to select any one of priority on determination speed, importance on determination accuracy, and importance on both determination speed and accuracy. When it is set so as to emphasize the speed of determination, the selection unit 205 determines whether or not the radio channel is disconnected based on the value of the carrier asynchronous activation signal 220 regardless of the value of the frame asynchronous activation signal 230. To do.
- the selection unit 205 determines whether or not the radio channel is disconnected based on the value of the frame asynchronous activation signal 230 regardless of the value of the carrier asynchronous activation signal 220. judge.
- the selection unit 205 indicates that the carrier asynchronous activation signal 220 indicates carrier asynchronous or the frame asynchronous activation signal 230 is frame asynchronous. Is determined that the wireless line has been disconnected. Then, the selection unit 205 generates an asynchronous activation signal 231 indicating whether or not the radio line is disconnected, and sends it to the modulation scheme control unit 203.
- the modulation scheme control unit 203 in the third embodiment determines whether or not the radio line with the opposite radio communication apparatus 1-2 is disconnected based on the asynchronous activation signal 231.
- the modulation control unit 203 receives the asynchronous activation signal 231 indicating that the wireless line is disconnected, the modulation method information signal 217 (modulation according to the modulation multi-level number selected when the wireless line is disconnected) is received.
- the modulation method information indicated by the (system information) is set as the opposite transfer modulation method information signal 218. Further, in this case, the modulation scheme control unit 203 sets a value (for example, “High”) indicating that the radio line is disconnected in the radio disconnection modulation scheme control signal 221, and sends it to the frame synchronization unit 202.
- the frame synchronization unit 202 in the third embodiment receives the radio disconnection modulation control signal 221 in which a value indicating that the radio line is disconnected is received, the demodulation synchronization modulation method information signal 215 is transmitted to the modulation processing information signal 215 for demodulation processing.
- the modulation scheme information indicated by the information signal 217 is overwritten.
- the frame synchronization unit 202 uses the asynchronous activation signal 231 directly as a timing signal for applying the wireless interruption modulation method information signal 217 instead of using the wireless interruption modulation method control signal 221. Also good.
- the frame synchronization unit 202 when the frame synchronization unit 202 receives the asynchronous activation signal 231 indicating that the radio line is disconnected, the frame synchronization unit 202 overwrites the modulation scheme information indicated by the radio modulation scheme information signal 217 on the demodulation processing modulation scheme information signal 215. It may be configured.
- the setting of the selection unit 205 is changed according to the environment in which the wireless communication device 1 is used, so that the detection of the disconnection of the wireless line can be quickly performed. It is possible to change the determination criteria such as emphasis on accuracy and accuracy.
- the present invention can be used for a fixed microwave radio transmission apparatus adopting an adaptive modulation system, a radio base station apparatus for mobile communication, and the like. It is possible to return.
- Wireless communication device 1-1 1-2 Opposite side wireless communication device 10
- Transmission block 101 TX baseband processing unit 102 modulation unit 20 receiving blocks 201
- Demodulator 202 Frame synchronization unit 203
- Modulation method controller 204 RX baseband processor 205 Selector
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Abstract
Description
変調多値数の大きな変調方式で無線伝搬を行っている最中に急激な無線伝搬路の劣化が発生すると、適応変調方式によって変調多値数がより小さな変調方式に切り替わるよりも前に無線回線が切断されてしまう。一般的に、高多値な変調方式ほど無線回線の接続に高い受信レベルを必要とするため、上記のように回線が切れてしまった場合には無線回線の復帰に高い受信レベルが必要となり、無線回線の復帰に時間を要してしまうという問題があった。
以下、第1実施形態における無線通信装置1(自装置1-1)について、図3及び図4を用いて説明する。図3は、第1実施形態における無線通信装置1の機能構成を表す概略ブロック図である。図4は、無線通信装置1で使用される信号及び無線フレームフォーマットの概略を表す図である。図4の詳細については後述する。
対向転送用変調方式情報信号218は、自装置1-1の変調方式制御部203によって判定された変調方式を表す信号であり、対向側無線通信装置1-2の変調部102によって適用されるべき変調方式を表す信号である。対向転送用変調方式情報信号218は、TXベースバンド出力信号112に信号多重され送信されることによって、対向側無線通信装置1-2へ通知される。対向転送用変調方式情報信号218は、対向側無線通信装置1-2のRXベースバンド処理部204によって抽出されて送信変調方式情報信号219として送信ブロック10へ送出され、対向側無線通信装置1-2から自装置1-1への無線通信に対する変調処理に用いられる。
また、フレーム同期部202は、フレーム同期確立を行った後、無線フレーム400の先頭を基準に自方向変調方式情報部412の位置を検出する。次に、フレーム同期部202は、検出された自方向変調方式情報部412から変調方式情報を抽出し、復調処理用変調方式情報信号215として復調部201に送出する。
変調方式制御部203は、上記の説明では変調多値数を選択することによって変調方式を決定していたが、変調多値数の選択のみならず他の値の選択によって変調方式を決定するように構成されても良い。例えば、複数の値の中から符号化率の値を選択することによって変調方式を決定するように構成されても良い。この場合も、符号化率の選択範囲として断絶時範囲及び適応変調範囲とが設定される。いずれの場合も、適応変調範囲としてより伝搬速度の高いものが設定され、断絶時範囲としては伝搬速度が遅くてもより耐性の強いものが設定される。
また、フレーム非同期と判定した場合、フレーム同期部202は、復調処理用変調方式情報信号215のみならず、オーバーヘッド部410中の転送用変調方式情報部413に対しても、無線断時変調方式情報信号217が示す変調方式情報を上書きするように構成されても良い。この場合、自装置1-1と対向側無線通信装置1-2との間において双方向の無線回線が従属的(同時)に断絶した場合であっても、自装置1-1の変調部102(すなわち、自装置1-1から対向側無線通信装置1-2への送信を行う変調部102)に対して、より早く断絶時範囲の変調方式情報を適用させることが可能となる。
図7は、第2実施形態における無線通信装置1の機能構成を表すブロック図である。以下、第2実施形態における無線通信装置1について、第1実施形態における無線通信装置1と異なる点について説明する。
図8は、第3実施形態における無線通信装置1の機能構成を表す概略ブロック図である。以下、第3実施形態における無線通信装置1について、第1実施形態及び第2実施形態における無線通信装置1と異なる点について説明する。
第3実施形態における復調部201は、キャリア非同期の検出を行い、検出結果を表すキャリア非同期発動信号220を生成する。復調部201は、例えばキャリア非同期を検出した場合はキャリア非同期発動信号220に“High”の値を設定し、キャリア非同期を検出しない場合(すなわちキャリア同期の場合)はキャリア非同期発動信号220に“Low”の値を設定する。そして、復調部201は、生成されたキャリア非同期発動信号220を選択部205に送出する。
1-1 自装置
1-2 対向側無線通信装置
10 送信ブロック
101 TXベースバンド処理部
102 変調部
20 受信ブロック
201 復調部
202 フレーム同期部
203 変調方式制御部
204 RXベースバンド処理部
205 選択部
Claims (17)
- 他の無線通信装置から無線伝搬路を介して無線信号を受信する受信部と、
前記他の無線通信装置との間の無線回線の断絶を検出する断絶検出部と、
前記無線回線の断絶が検出された場合には、それまでの無線通信で使用されていた変調方式よりも悪い伝搬路状態で通信が可能となる変調方式を選択する変調方式制御部と、
前記変調方式制御部によって選択された変調方式を、前記他の無線通信装置が自装置に対する送信信号生成時に適用するために、前記他の無線通信装置へ通知する送信部と、
を備える無線通信装置。 - 前記受信部によって受信された無線信号に基づいて前記無線伝搬路の状態を推定する無線伝搬路推定部をさらに備え、
前記変調方式制御部は、前記断絶検出部によって前記無線回線の断絶が検出されていない場合には、前記無線伝搬路推定部の推定結果に基づいて適応的に変調方式を選択する請求項1に記載の無線通信装置。 - 前記変調方式制御部は、前記断絶検出部によって前記無線回線の断絶が検出されていない場合には、第一範囲に含まれる変調方式の中から前記無線伝搬路推定部の推定結果に基づいて適応的に変調方式を選択し、前記無線回線の断絶が検出された場合には、前記第一範囲に含まれる変調方式よりも悪い伝搬路状態で通信が可能となる変調方式により構成される第二範囲に含まれる変調方式の中から変調方式を選択する請求項2に記載の無線通信装置。
- 前記変調方式制御部は、前記無線回線の断絶が検出された場合には、選択可能な中から最も小さい変調多値数を用いた変調方式を選択する請求項1又は2に記載の無線通信装置。
- 前記断絶検出部は、前記受信部によって受信された無線信号において、無線フレームが同期状態でない場合に無線回線が断絶したと判定する請求項1~4のいずれか1項に記載の無線通信装置。
- 前記断絶検出部は、前記受信部によって受信された無線信号において、キャリアが同期状態でない場合に無線回線が断絶したと判定する請求項1~4のいずれか1項に記載の無線通信装置。
- 前記断絶検出部は、前記受信部によって受信された無線信号において、無線フレームが同期状態であるか否か、及び、キャリアが同期状態であるか否か、に基づいて無線回線の断絶を検出する請求項1~4のいずれか1項に記載の無線通信装置。
- 請求項1~7のいずれか1項に記載の無線通信装置と、
請求項1に記載の他の無線通信装置とを備える無線通信システム。 - 前記他の無線通信装置は、
前記無線通信装置から前記選択された変調方式を示す通知を受信する他の受信部と、
前記他の受信部によって受信された前記選択された変調方式に基づいて前記無線通信装置へ送信を行う他の送信部と、
を備える請求項8に記載の無線通信システム。 - 他の無線通信装置から無線伝搬路を介して無線信号を受信し、
前記他の無線通信装置との間の無線回線の断絶を検出し、
前記無線回線の断絶が検出された場合には、それまでの無線通信で使用されていた変調方式よりも悪い伝搬路状態で通信が可能となる変調方式を選択し、
選択された変調方式を、前記他の無線通信装置が自装置に対する送信信号生成時に適用するために、前記他の無線通信装置へ通知する
無線通信方法。 - 受信された前記無線信号に基づいて前記無線伝搬路の状態を推定し、
前記無線回線の断絶が検出されていない場合には、前記無線伝搬路の状態の推定結果に基づいて適応的に変調方式を選択する請求項10に記載の無線通信方法。 - 前記無線回線の断絶が検出されていない場合には、第一範囲に含まれる変調方式の中から前記無線伝搬路の状態の推定結果に基づいて適応的に変調方式を選択し、前記無線回線の断絶が検出された場合には、前記第一範囲に含まれる変調方式よりも悪い伝搬路状態で通信が可能となる変調方式により構成される第二範囲に含まれる変調方式の中から変調方式を選択する請求項11に記載の無線通信方法。
- 前記無線回線の断絶が検出された場合には、選択可能な中から最も小さい変調多値数を用いた変調方式を選択する請求項10又は11に記載の無線通信方法。
- 受信された前記無線信号の無線フレームが同期状態でない場合に前記無線回線が断絶したと判定する請求項10~13のいずれか1項に記載の無線通信方法。
- 受信された前記無線信号のキャリアが同期状態でない場合に前記無線回線が断絶したと判定する請求項10~13のいずれか1項に記載の無線通信方法。
- 受信された前記無線信号の無線フレームが同期状態であるか否か、及び受信された前記無線信号のキャリアが同期状態であるか否かに基づいて前記無線回線の断絶を検出する請求項10~13のいずれか1項に記載の無線通信方法。
- 無線伝搬路を介して無線通信を行う第1無線通信装置及び第2無線通信装置を含む無線通信システムが行う無線通信方法であって、
前記第1無線通信装置が、前記第2無線通信装置から前記無線伝搬路を介して無線信号を受信し、
前記第1無線通信装置が、前記第2無線通信装置との間の無線回線の断絶を検出し、
前記第1無線通信装置が、前記無線回線の断絶が検出された場合には、それまでの無線通信で使用されていた変調方式よりも悪い伝搬路状態で通信が可能となる変調方式を選択し、
前記第1無線通信装置が、前記選択された変調方式を、前記第2無線通信装置へ通知し、
前記第2無線通信装置が、前記第1無線通信装置から前記選択された変調方式を示す通知を受信し、
前記第2無線通信装置が、受信された前記選択された変調方式に基づいて前記第1無線通信装置へ送信を行う
無線通信方法。
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