JP2006191701A - Transmitter and transmission method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately decide the modulation system of a digital modulation signal and an error correction system on the receiving side. <P>SOLUTION: In a communications system, the modulation system and the error correction system are switched adaptively, in response to the state of a transmission line, and the transmission-line error resistance is improved. In the communications system, the signals MX, MY, CX and CY of the modulation system and the error correction system used on the transmission side are arranged at discrete places in the same frame and transmitted. Accordingly, even if the transmission signals receive fading and fluctuations of the transmission line, the possibility of both the deteriorations of the discretely arranged both signals MX and MY and CX and CY is lowered. Consequently, a modulation-system information signal and/or an error-correction system information signal can be restored accurately on the receiving side. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a transmission apparatus and a transmission method, and more particularly to a frame configuration in a digital radio system.

  Conventionally, a receiving apparatus in a communication system using a digital wireless communication system restores an original signal from a received signal by subjecting the received signal to digital demodulation processing opposite to the digital modulation method performed on the transmitting side. It has become.

  In addition, there is a wireless communication system in which transmission / reception is performed by adaptively switching between a modulation scheme and an error correction scheme according to the state of the propagation path. In this type of wireless communication system, the transmission / reception apparatus determines the current propagation path state based on the SIR (Signal to Interference Ratio) or the like of the signal received from the other party, and switches the modulation method according to the state. .

  In practice, when the propagation path condition is good, the information symbol is digitally modulated using a multi-level modulation method with a large amount of information transmission per symbol, for example, 64QAM, and redundancy is used as an error correction method. A high error correction code is added and transmitted. On the other hand, when the state of the propagation path is bad, the information symbol is digitally modulated using a modulation method with a small amount of information transmission per symbol, such as 16QAM or QPSK modulation method, and an error correction method. As described above, an error correction code with low redundancy is added and transmitted.

  In this way, in this type of communication system, the modulation method is transmitted to the transmission signal in order to transmit to the reception side which modulation method the transmission signal is modulated and which error correction method is used. Is added. That is, a receiving apparatus of this type of communication system includes a plurality of demodulation units corresponding to a plurality of modulation schemes and a plurality of error correction decoding units corresponding to a plurality of error correction schemes, and the transmitted modulation scheme information signal The original data is restored by performing demodulation processing and error correction processing according to the error correction information signal.

  As a frame structure related to information symbols because of the modulation multi-value number, for example, the structure described in Non-Patent Document 1 is known.

  FIG. 11 shows a conventional frame configuration. That is, one ramp symbol R, six synchronization symbols SW, one pilot symbol P, one modulation scheme information symbol I, and 18 data symbols DATA are arranged in order from the top.

The receiving apparatus that receives the signal having such a frame configuration determines the modulation scheme of the data symbol DATA from the modulation scheme information symbol I, and demodulates the data symbol DATA using a demodulation scheme corresponding to the determined modulation scheme.
"Development of an adaptive modulation experiment system for land mobile communication-Outline of operation mode", Hamaguchi et al., IEICE Communication Society B-5-135 pp. 388 September 1997

  By the way, if the determination of the modulation scheme information symbol I or the error correction scheme information symbol (not shown) is wrong in the receiving apparatus, the data obtained by demodulating and decoding the data symbol DATA will be erroneous. Therefore, it is necessary to transmit modulation method information and error correction method information to the receiver with fewer errors. In particular, in wireless communication, there is a possibility that modulation method information and error correction method information may be erroneously determined on the receiving side due to fading due to noise or propagation path fluctuation. As a result, communication quality is reduced.

  The present invention has been made in view of the above points, and provides a transmission apparatus and a transmission method capable of accurately determining a modulation method and an error correction method of a digital modulation signal on the receiving side and improving communication quality. The purpose is to do.

  In order to solve this problem, the transmission apparatus of the present invention includes a modulation method information signal generation unit that generates an information signal related to an information symbol modulation method, and an error correction method information signal generation that generates an information signal related to an information symbol error correction method. And a frame forming unit that forms a transmission frame by discretely arranging modulation scheme information signals and / or error correction scheme information signals, and a transmission unit that transmits the transmission frame.

  According to this configuration, since the modulation scheme information signal and / or the error correction scheme information signal are discretely arranged, both the discretely arranged signals are deteriorated even if the transmission signal is subjected to fading or propagation path fluctuation. The possibility of deterioration is reduced. As a result, the receiving side can accurately restore the modulation scheme information signal and / or the error correction scheme information signal.

  Further, the transmission apparatus of the present invention employs a configuration in which the modulation scheme information signal generation means and / or the error correction scheme information signal generation means generate a modulation scheme information signal and an error correction scheme information signal composed of a plurality of symbols.

  According to this configuration, since the channel error tolerance is improved as compared with the case where the modulation scheme information signal and / or error correction scheme information signal is formed of a single symbol, the modulation scheme information signal and / or error correction scheme on the receiving side. The information signal can be restored more accurately.

  In the transmission apparatus of the present invention, the frame forming means adopts a configuration in which the modulation scheme information signal and / or the error correction scheme information signal are discretely arranged at positions separated by a predetermined time or more in consideration of the Doppler frequency.

  According to this configuration, even when the received electric field strength drops due to fading, the drop in the received electric field strength at any position of the modulation scheme information signal and the error correction scheme information signal arranged in a discrete manner is within an allowable value. Therefore, even when fading occurs, the error rate of the modulation scheme information signal and the error correction scheme information signal can be suppressed. For example, if the discrete position is selected as an extremely close position, when the received electric field strength drops due to fading, the received electric field strength of all symbols of the discretely arranged symbols drops, and the modulation method and error correction method information signal Since all error rates are high, the present invention takes this into consideration, and optimally selects positions to be discretely arranged in consideration of Doppler frequencies that have a deep connection with fading.

  The transmission apparatus of the present invention employs a configuration in which the transmission means transmits the transmission frame with the maximum signal point amplitude of the modulation scheme information signal and / or error correction scheme information signal larger than the maximum signal point amplitude of the information symbol.

  According to this configuration, since the signal point interval between the modulation scheme information signal and the error correction scheme information signal is increased, the modulation scheme information signal and / or the error correction scheme information signal can be restored more accurately on the receiving side.

  The transmission apparatus according to the present invention adopts a configuration in which a modulation scheme information signal and / or an error correction scheme information signal is transmitted after BPSK modulation or QPSK modulation.

  According to this configuration, since the BPSK modulation or the QPSK modulation having a high error resistance is adopted as the modulation scheme of the modulation scheme information signal and / or the error correction scheme information signal, the modulation scheme information signal and / or the error correction scheme information signal on the receiving side It can be restored more accurately.

  Further, the transmission apparatus of the present invention includes a modulation method information signal generating unit that generates an information signal related to an information symbol modulation method, an error correction method information signal generating unit that generates an information signal related to an information symbol error correction method, and a modulation method. An OFDM modulation means for forming an orthogonal frequency division multiplexed signal in which information signals and / or error correction method information signals are discretely arranged on a plurality of mutually orthogonal subcarriers is adopted.

  According to this configuration, even when frequency selective fading occurs, the modulation scheme information signal and / or the modulation scheme information signal of at least one subcarrier of the error correction scheme information signal discretely arranged on different subcarriers and / or Since there is a high possibility that the signal level drop due to fading is reduced in the error correction method information signal, the reception side can obtain a modulation method information signal and / or error correction method information signal with a signal level higher than necessary. .

  The receiving apparatus of the present invention includes an information signal, a modulation scheme information signal related to the modulation scheme of the information signal, and an error correction scheme information signal related to the error correction scheme of the information signal, and the modulation scheme information signal and the error correction information signal are A receiving apparatus for receiving and demodulating received signals arranged at discrete positions in the same frame, and receiving power for modulation method information signals and error correction method information signals at discrete positions arranged Receiving power detection means for detecting, and modulation method by weighting the modulation method information signal and the error correction method information signal arranged at the position corresponding to the receiving power detected by the receiving power detection means in accordance with the receiving power. And a determination means for determining an error correction method, a demodulation process corresponding to the modulation method and the error correction method determined by the determination means, and It adopts a configuration comprising a signal selecting means for selecting a demodulated signal obtained by performing Ri correction processing.

  According to this configuration, attention is paid to the fact that the error at the time of demodulation becomes lower as the signal with the higher reception power, and the modulation scheme information signal and the error correction scheme information signal arranged discretely are weighted by the reception power. The modulation method and error correction method were determined. As a result, an accurate modulation scheme and error correction scheme can be determined, and a high-quality received signal can be obtained by performing demodulation processing and error correction processing accordingly.

  The receiving apparatus of the present invention includes an information signal, a modulation scheme information signal related to the modulation scheme of the information signal, and an error correction scheme information signal related to the error correction scheme of the information signal, and includes the modulation scheme information signal and the error correction scheme information signal. Is a receiving device for receiving and demodulating received signals arranged at discrete positions in the same frame, and receiving power for modulation method information signals and error correction method information signals at discrete positions arranged Receiving power detecting means for detecting the signal, and selecting a modulation scheme information signal and an error correction scheme information signal arranged at a position corresponding to the reception power detected by the receiving power detector to determine the modulation scheme and error correction scheme Select the decision means and the demodulated signal obtained by performing demodulation and error correction processing corresponding to the modulation method and error correction method determined by the decision means It adopts a configuration comprising a signal selecting means that.

  According to this configuration, attention is paid to the fact that the error at the time of demodulation is lower as the signal has a higher received power, and the received power is higher among the modulation scheme information signal and the error correction scheme information signal arranged discretely. Select the modulation method and error correction method. As a result, it is possible to obtain an accurate modulation scheme and error correction scheme information signal with few errors at the time of demodulation, and a high-quality received signal can be obtained by performing demodulation processing and error correction processing accordingly.

  Further, the transmission method of the present invention generates a modulation scheme information signal related to a modulation scheme of information symbols, generates an error correction scheme information signal related to an error correction scheme of information symbols, and generates a modulation scheme information signal and / or an error correction scheme information signal. A transmission frame is formed by arranging discretely, and the transmission frame is transmitted.

  According to this method, since the modulation scheme information signal and / or the error correction scheme information signal are discretely arranged, both the discretely arranged signals are deteriorated even if the transmission signal is subjected to fading or propagation path fluctuation. The possibility of deterioration is reduced. As a result, the modulation scheme information signal and / or the error correction scheme information signal can be accurately restored on the receiving side.

  The reception method of the present invention includes an information signal, a modulation method information signal related to the modulation method of the information signal, and an error correction method information signal related to the error correction method of the information signal, and includes the modulation method information signal and the error correction method information signal. Is a reception method for receiving and demodulating received signals arranged at discrete positions in the same frame, and receiving power for modulation method information signals and error correction method information signals at discrete positions arranged Detects and selects a modulation scheme information signal and an error correction scheme information signal arranged at a position corresponding to the detected received power, determines a modulation scheme and an error correction scheme, and corresponds to the determined modulation scheme and error correction scheme A demodulated signal obtained by performing demodulation processing and error correction processing is selected.

  According to this method, paying attention to the fact that the error at the time of demodulation becomes lower as the signal at the position where the reception power is larger, among the modulation scheme information signal and the error correction scheme information signal arranged discretely, the reception power is larger. The other modulation system information signal and error correction system information signal are selected. As a result, it is possible to obtain an accurate modulation scheme and error correction scheme information signal with few errors at the time of demodulation, and a high-quality received signal can be obtained by performing demodulation processing and error correction processing accordingly.

  According to the present invention, in a communication system adapted to adaptively switch between a modulation scheme and an error correction scheme according to a propagation path state to improve propagation path error tolerance, the modulation scheme and error correction used on the transmission side. By arranging the method information at discrete positions in the same frame, the modulation / error correction method and error correction method performed on the transmission side can be accurately determined on the reception side, so that communication quality can be improved. it can.

  The essence of the present invention is that the modulation scheme and error correction used on the transmission side in a communication system adapted to adaptively switch the modulation scheme and error correction scheme according to the propagation path state to improve propagation path error tolerance. The system signal is transmitted at discrete positions in the same frame.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
In FIG. 1, reference numeral 100 indicates the overall configuration of the transmission apparatus according to Embodiment 1 of the present invention. The transmission apparatus 100 can adaptively select an error correction method and a modulation method according to the state of the propagation path. Transmitting apparatus 100 inputs transmission digital signal D1 to error correction A encoder 101 and error correction B encoder 102.

  The error correction A encoder 101 and the error correction B encoder 102 perform error correction processing with different redundancy. Specifically, the error correction B encoder 102 performs error correction processing with higher redundancy than the error correction A encoder 101, and thus the error correction B encoder 102 performs error correction with higher error tolerance. Encoded data is obtained. Each error correction encoded data obtained by the error correction A encoder 101 and the error correction B encoder 102 is sent to the digital signal selection unit 103.

  Further, the transmission apparatus 100 includes a modulation scheme / error correction scheme determination unit 104, and a propagation path estimation signal S1 is input to the modulation scheme / error correction scheme determination unit 104. This propagation path estimation signal S1 is obtained based on the SIR (Signal to Interference Ratio) or the like of a signal received by a receiving unit (not shown) from a radio station as a communication partner.

  The modulation scheme / error correction scheme determination unit 104 determines the modulation scheme and error correction scheme according to the propagation path estimation signal S1. In practice, when the propagation path estimation signal S1 indicating that the influence of fading fluctuation and noise is large and the propagation path state is bad is input, for example, BPSK (Binariphase Phase Shift Keying) modulation or QPSK modulation is used as a modulation method. In this way, a modulation scheme with high error tolerance is selected, and an error correction scheme with high redundancy is determined as the error correction scheme.

  The modulation scheme information S2 and the error correction scheme information S3 determined by the modulation scheme / error correction scheme determination section 104 are sent to the digital signal selection section 103, the transmission baseband signal selection section 106, and the control information modulation section 105.

  The digital signal selection unit 103 selects one of the outputs of the error correction A encoder 101 or the error correction B encoder 102 based on the error correction method information S3, and the BPSK modulation unit 107, the QPSK modulation unit 108, the 16QAM modulation unit 109, and The data is sent to the 64QAM modulator 110.

  Each of the modulation units 107 to 110 performs digital modulation processing on the digital signal input from the digital signal selection unit 103 and sends the modulated signal to the transmission baseband signal selection unit 106. The transmission baseband signal selection unit 106 selects and outputs a modulation signal corresponding to the modulation information S2 from the plurality of input modulation signals. For example, when the state of the propagation path is poor, modulation scheme information S2 indicating BPSK modulation or QPSK modulation is input, and a BPSK modulation signal or QPSK modulation signal corresponding to this is selectively output.

  The frame configuration unit 111 receives a modulation signal selected by the transmission baseband signal selection unit 106 and a signal indicating the modulation scheme and error correction scheme modulated by the control information modulation unit 105. Incidentally, the control information modulation unit 105 performs modulation processing with high error resistance such as BPSK modulation and QPSK modulation on the input signal. As a result, the error tolerance of the signal relating to the modulation scheme and error correction scheme, which are very important information on the receiving side, is increased.

  As shown in FIG. 2, the frame configuration unit 111 according to the present embodiment, in order from the head of the frame, includes one pilot symbol P, three consecutive modulation scheme information symbols MX, and three consecutive error correction scheme information symbols. CX, 128 symbol data symbol DATA, pilot symbol P, data symbol DATA, pilot symbol P, 10 symbol unique word UW, pilot symbol P, modulation scheme information symbol MY, error correction scheme information symbol CY, data symbol DATA, pilot Symbol P, data symbol DATA, and pilot symbol P are arranged in this order.

  As is apparent from FIG. 2, the modulation system information symbols MX and MY and the error correction information symbols CX and CY are discretely arranged in the same frame. That is, the same modulation scheme information symbol MY as the modulation scheme information symbol MX is provided at a different position in the frame, and similarly, the same error correction scheme information symbol CY as the error correction scheme information symbol CX is provided at a different position in the frame. ing.

  A method of modulating a plurality of consecutive symbols (three symbols in this embodiment) representing the modulation scheme information by the control information modulator 105 will be described. Considering the case where the QPSK modulation shown in FIG. 3 is performed on the modulation scheme information symbols MX and MY that are three symbols continuous, for example, when the modulation scheme of the information symbols is BPSK modulation, the signal point 201 is used. There is a method of mapping the signal point 202, the signal point 203 in the case of 16QAM, and the signal point 204 in the case of 64QAM in the modulation scheme information symbols MX and MY.

  As another modulation method, for example, when the modulation method of the information symbol is BPSK modulation, it is mapped to 201, 202, 203 in time order, and in the case of QPSK modulation, it is mapped to 202, 204, 203 in time order, and 16QAM In this case, there is a method of mapping to 204, 201, 203 in time order, and in 64QAM, mapping to 202, 204, 201 in time order.

  Next, a method of modulating a plurality of consecutive symbols (3 symbols in the embodiment) representing error correction method information will be described. Considering the case where the BPSK modulation shown in FIG. 4 is performed on the error correction method information symbols CX and CY that are three symbols continuous, for example, when the error correction method A is used, the signal point 301 is set as the error correction method. When B is used, there is a method of mapping the signal point 302 in the error correction method information symbols CX and CY.

  As another modulation method, for example, when error correction method A is used, it is mapped to 301, 302, 302 in time order, and when error correction method B is used, 302, 301, 301 in time order. There is a way to map to.

  Here, when the former method is used (when the signal point is fixed and mapped), high-accuracy estimation is possible with a small number of symbols, and on the receiving side, a simple method called BPSK, QPSK modulation detection, The modulation scheme and error correction scheme can be estimated. On the other hand, when the latter method is used (when signal points are mapped in time order), symbols for time synchronization between the transmission apparatus and the reception apparatus are deleted, and modulation scheme information symbols and error correction scheme information symbols are used. Thus, it can be used as a symbol for time synchronization between the transmission device and the reception device. On the other hand, in the receiving apparatus, a complicated calculation called a correlation calculation of sequences is required.

  The signal output from the frame configuration unit 111 is subjected to digital-analog conversion and signal amplification processing by the wireless unit 112 and then transmitted from the antenna 113.

  FIG. 5 shows a configuration of receiving apparatus 500 that receives and demodulates a signal transmitted from transmitting apparatus 100. The receiving device 500 obtains an orthogonal baseband signal by performing predetermined wireless reception processing such as amplification processing and analog-digital conversion processing on the reception signal received by the antenna 501 by the wireless unit 502, and obtains the orthogonal baseband signal from the detection unit 503. 506 and the modulation method / error correction method estimation unit 507.

  The detection units 503 to 506 are constituted by a BPSK detection unit 503, a QPSK detection unit 504, a 16QAM detection unit 505, and a 64QAM detection unit 506. The reception baseband signals detected by the detection units 503 to 506 are received digital signals. The data is sent to the selection unit 508.

  The modulation scheme / error correction scheme estimation unit 507 detects the modulation scheme information symbols MX, MY and the error correction scheme information symbols CX, CY of FIG. 2 from the received orthogonal baseband signal, and these information symbols MX, MY, CX , The modulation scheme and the error correction scheme are estimated based on CY, and the estimation result S10 is sent to the received digital signal selection section 508 and the signal selection section 509.

  The modulation scheme / error correction scheme estimation unit 507 is configured as shown in FIG. That is, modulation scheme / error correction scheme estimation section 507 inputs the received quadrature baseband signal output from radio section 502 to modulation scheme / error correction scheme signal detection section 520. The modulation scheme / error correction scheme signal detector 520 synchronously detects the modulation scheme information symbols MX and MY and the error correction scheme information symbols CX and CY based on the unique word UW included in the received orthogonal baseband signal, On the other hand, by performing BPSK demodulation processing or QPSK demodulation processing, modulation scheme information symbols MX and MY and error correction scheme information symbols CX and CY are detected and demodulated.

  The modulation scheme / error correction scheme information X determination unit 521 uses the modulation scheme information symbol MX and error correction information CX illustrated in FIG. 2 among the detected modulation scheme information symbols MX and MY and error correction scheme information symbols CX and CY. Judge and detect. Similarly, modulation scheme / error correction scheme information Y determination section 522 includes modulation scheme information MY and error correction information shown in FIG. 2 among detected modulation scheme information symbols MX and MY and error correction scheme information symbols CX and CY. CY is determined and detected.

  As is apparent from FIG. 2, the modulation scheme information symbol MX and the error correction scheme information symbol CX, and the modulation scheme information symbol MY and the error correction scheme information symbol CY are discretely arranged at distant positions in the transmission frame. And regularly arranged. Therefore, the modulation scheme / error correction scheme information X determination section 521 and the modulation scheme / error correction scheme information Y determination section 522 can easily determine and detect these information symbols based on the pilot symbol P, for example.

  Modulation scheme / error correction scheme information X reception power calculation section 523 calculates the reception power of modulation scheme information symbol MX and error correction scheme information symbol CX. Similarly, modulation scheme / error correction scheme information Y reception power calculation section 524 calculates the reception power of modulation scheme information symbol MY and error correction scheme information symbol CY. Actually, the positions of the modulation scheme information symbol MX and the error correction scheme information symbol CX, the modulation scheme information symbol MY, and the error correction scheme information symbol CY, which are discretely arranged in each frame, are assigned to the pilot symbols P and the unique symbols. Detection is performed based on the word UW, and the reception power of the modulation scheme information symbol MX and the error correction scheme information symbol CX and the reception power of the modulation scheme information symbol MY and the error correction scheme information symbol CY are calculated.

  The modulation method / error correction method determination unit 525 uses the modulation method / error correction method information X determination unit 521 to obtain the modulation method / error correction method information X reception power calculation unit. Weighting is performed by the received power obtained by 523. Similarly, the modulation scheme / error correction scheme determination unit 525 converts the modulation scheme information symbol MY and the error correction scheme information symbol CY obtained by the modulation scheme / error correction scheme information Y determination section 522 into modulation scheme / error correction scheme information. The received power obtained by the Y received power calculation unit 524 is weighted.

  The modulation scheme / error correction scheme determination unit 525 determines the modulation scheme and error correction scheme by adding the modulation scheme information symbols MX and MY and the error correction scheme information symbols CX and CY weighted by the reception power. In this way, the modulation scheme / error correction scheme estimation unit 507 uses the received power at each discrete position for the modulation scheme information symbols MX and MY and the error correction scheme information symbols CX and CY that are discretely arranged in the transmission frame. The final modulation scheme information and error correction scheme information are obtained by detecting and weighting and adding the modulation scheme information symbols MX and MY and the error correction scheme information symbols CX and CY based on the received power.

  Returning to FIG. 5, the receiving apparatus 500 will be described. The reception digital signal selection unit 508 outputs an output corresponding to the modulation scheme estimated by the modulation scheme / error correction scheme estimation unit 507 from the outputs of the BPSK detection unit 503, the QPSK detection unit 504, the 16QAM detection unit 505, and the 64QAM detection unit 506. Is sent to the subsequent error correction A decoder 510 and error correction B decoder 511.

  Received decoded signals decoded using different error correction methods by error correction A decoder 510 and error correction B decoder 511 are sent to signal selection section 509. The signal selection unit 509 selects an output corresponding to the error correction method estimated by the modulation method / error correction method estimation unit 507 from the error correction A decoder 510 and the error correction B decoder 511, and this is finally received and decoded. Output as a signal.

  In the above configuration, transmitting apparatus 100 adaptively digitally modulates data symbol DATA according to the state of the propagation path using a modulation scheme with different error resilience and uses error correction schemes with different error resilience to perform error correction. Correct it.

  In addition to this, the transmission apparatus 100 transmits modulation scheme information MX and MY and error correction scheme information CX and CY discretely arranged in a transmission frame. The modulation scheme information MX and MY and the error correction scheme information CX and CY are modulated and transmitted using a modulation scheme having high error resistance such as BPSK modulation and QPSK modulation.

  The receiving apparatus 500 that receives this transmission signal first calculates reception power for the modulation scheme information signals MX and MY and the error correction scheme information signals CX and CY that are discretely arranged. Here, as shown in FIG. 7, the received power of the received signal varies in time due to the influence of fading or the like. As a result, among the modulation scheme information signals MX and MY and the error correction scheme information signals CX and CY arranged discretely, for example, the modulation scheme information signal MX and the error correction scheme information signal CX have a reception power (reception field strength). The received power of the modulation method information signal MY and the error correction method information signal CY is increased.

  Here, since the error rate at the time of demodulation is generally smaller for a signal having a large received power, the receiving apparatus 500 applies a small weighting factor to the modulation scheme information signal MX and the error correction scheme information signal CX having a small reception power. In addition, the modulation scheme information signal MY and the error correction scheme information signal CY having a large reception power are multiplied by a large weighting factor. These added values are used as final modulation system information and error correction system information.

  As a result, accurate modulation scheme information and error correction scheme information can be obtained even when propagation path fluctuations and fading occur.

  The receiving apparatus 500 selects the data demodulated by the demodulation method corresponding to the acquired modulation method information, and selects the received decoded data subjected to the error correction decoding process corresponding to the acquired error correction method information. Get the received signal.

  As a result, a signal demodulated and decoded by an appropriate modulation method and an appropriate error correction method can be obtained, so that reception quality can be improved.

  Here, a discrete arrangement method for improving the estimation accuracy of the modulation scheme and error correction scheme information will be described. In order to correctly restore the modulation scheme and error correction scheme information, it is only necessary that the received electric field strength of each information symbol is a certain level or higher. Therefore, it is sufficient that symbols having a received electric field strength of a certain level or more exist in the modulation scheme information and error correction scheme information symbols that are discretely arranged.

  Therefore, in this embodiment, the time positions to be discretely distributed are set to the maximum Doppler frequency defined in the wireless communication system to which the transmission device 100 and the reception device 500 belong, taking into consideration the time that is the inverse of the Doppler frequency. , Modulation scheme information signals MX and MY and error correction scheme information signals CX and CY are arranged at positions separated by about 1 / fd time.

  As a result, even when the received electric field strength drops due to fading, the reception electric field strength at any position of the modulation scheme information signals MX and MY and the error correction scheme information signals CX and CY that are discretely arranged is allowed to drop. Since it can be suppressed within the value, the error rate of the modulation scheme information and the error correction scheme information can be suppressed.

  For example, if the discrete position is selected as an extremely close position, when the received electric field strength drops due to fading, the received electric field strength of all symbols of the discretely arranged symbols drops, and all the modulation method and error correction method information The error rate becomes higher. Considering this, the position where the modulation method and the error correction information are arranged may be near the head, near the middle, and near the tail in one frame.

  According to the above configuration, when the modulation scheme and the error correction scheme are adaptively switched according to the state of the propagation path, the modulation scheme information symbols MX and MY and the error correction scheme information are discretely included in the transmission frame on the transmission side. The symbols CX and CY are arranged and transmitted, and the reception power of the modulation scheme information symbols MX and MY and the error correction scheme information symbols CX and CY at each position discretely arranged on the reception side is detected, and the received power By obtaining the final modulation scheme and error correction scheme by weighting the modulation scheme information and error correction scheme information that are discretely arranged according to the size, and obtaining the demodulated decoded signal based on that, noise and Even when propagation path fluctuations occur, it is possible to obtain the transmission device 100 and the reception device 500 that can suppress deterioration in communication quality.

  Further, the modulation scheme information symbols MX and MY and the error correction scheme information symbols CX and CY are not one symbol, but a plurality of symbols (three symbols in the embodiment), so that the modulation scheme information and error correction are further improved. It becomes possible to transmit the system information accurately.

  Furthermore, modulation scheme information symbols MX, MY and error correction scheme information symbols CX, CY are further modulated by BPSK modulation or QPSK modulation, which is a modulation scheme resistant to fading and propagation path variation. It is possible to accurately transmit the system information and the error correction system information.

  In the above-described embodiment, a case has been described in which final modulation scheme information and error correction scheme information are obtained by weighting modulation scheme information and error correction information that are discretely arranged according to reception power. However, the present invention is not limited to this, and only the modulation scheme information and error correction scheme information having the larger reception power may be used as final modulation scheme information and error correction scheme information. For example, as shown in FIG. 7, when the reception power of the modulation scheme information MY and the error correction scheme information CY is larger than the reception power of the modulation scheme information MX and the error correction scheme information CX, the modulation scheme information MY and The error correction method information CY may be selected.

  In the above-described embodiment, the case where the transmission power of the symbol indicating the modulation scheme and the error correction scheme is made the same as the transmission power of the data symbol and the pilot symbol has been described. If the transmission power (that is, the maximum signal amplitude) is made larger than the transmission power (maximum signal amplitude) of other symbols, modulation method information and error correction method information can be obtained more accurately on the receiving side.

  In the above-described embodiment, the case where the transmission apparatus 100 forms the transmission frame shown in FIG. 2 has been described. However, the frame configuration is not limited to FIG. 2, and the modulation scheme information symbol and the error correction scheme information symbol are used. Three symbols are continuous and discretely inserted at two locations, but this is not a limitation.

  The configurations of the transmission apparatus, reception apparatus, modulation scheme, and error correction scheme estimation section of the present invention are not limited to those shown in FIGS. In particular, in the embodiment, since there are two positions where the modulation scheme information and the error correction scheme information are discretely arranged, the modulation scheme / error correction scheme information in the configuration of the modulation scheme / error correction scheme estimation unit 507 in FIG. Two determination units and two modulation method / error correction method information reception power calculation units are provided. These numbers depend on the number of discretely inserted modulation method information symbols and error correction method information symbols. It suffices to provide as many as required.

  Further, in the above-described embodiment, the case where the modulation scheme information and the error correction scheme information are transmitted has been described. However, even when the present invention is applied to a transmission apparatus and a reception apparatus that transmit only one of them, the embodiment The same effect can be obtained. For example, if the present invention is used in a system that transmits only modulation scheme information, the modulation scheme information can be accurately transmitted to the receiving side.

(Embodiment 2)
In FIG. 8, in which parts corresponding to those in FIG. 1 are assigned the same reference numerals, 800 indicates the overall configuration of the transmission apparatus according to Embodiment 2 of the present invention. The transmission apparatus is configured to transmit a transmission signal by performing orthogonal frequency division multiplexing using an OFDM (Orthogonal Frequency Division Multiplexing) method.

  Specifically, the output of the frame configuration unit 111 is subjected to serial / parallel conversion processing by a serial / parallel conversion unit (S / P conversion unit) 801, and an inverse Fourier transform unit (idft) 802 performs inverse Fourier processing on the processed parallel signal. By performing the conversion process, a transmission signal having a signal arrangement as shown in FIG. 9A or 9B is formed. Incidentally, the division in the frequency direction of FIG. 9 shows the division of the subcarrier. That is, FIG. 9 shows an example in which a modulated signal is transmitted using 10 subcarriers that are orthogonal to each other.

  In the signal arrangement shown in FIG. 9A, error correction method information symbols are discretely arranged on different frequency subcarriers in the same time, and modulation method information symbols are discretely arranged on different frequency subcarriers in the same time. Has been. With such an arrangement, for example, even when frequency selective fading occurs such that the gain of a frequency on the propagation path drops, the signal level of one error correction scheme information symbol and modulation scheme information symbol is maintained. Therefore, an error correction method information signal and a modulation method information signal having a signal level equal to or higher than a predetermined value can be obtained on the receiving side.

  In the signal arrangement shown in FIG. 9B, the error correction method information symbols are arranged at different times on the same frequency subcarrier, and the modulation method information symbols are arranged at different times on the same frequency subcarrier. With this arrangement, for example, when propagation path fluctuations occur over time, the signal levels of the error correction scheme information symbol and the modulation scheme information symbol at a certain point in time are maintained. It is possible to obtain an error correction method information signal and a modulation method information signal having the above signal levels.

  FIG. 10 shows the configuration of a receiving apparatus that receives the OFDM signal transmitted by transmitting apparatus 800. In FIG. 10, in which the same reference numerals are assigned to the corresponding parts as in FIG. 5, the receiving apparatus 1000 performs Fourier transform processing on the output of the radio section 502 by the Fourier transform section (dft) 1001, and the signal after Fourier transform is parallel-serial Parallel / serial conversion is performed by a conversion unit (P / S conversion unit) 1002. As a result, a signal having a frame configuration as shown in FIG. 2 is obtained from the orthogonal frequency division multiplexed reception signal. The subsequent processing is the same as that described in the first embodiment.

  According to the above configuration, when a transmission signal including an error correction method information signal and a modulation method information signal is transmitted by orthogonal frequency division multiplexing, the error correction method information signal and the modulation method information signal are divided into different sub-bands. By arranging the carrier or the same subcarrier at positions separated in time, it is possible to obtain an error correction method information signal and a modulation method information signal that are higher than the signal level required on the receiving side. As a result, the modulation method and error correction method of the digital modulation signal can be accurately determined on the receiving side.

  In this embodiment, the case where the OFDM modulation processing is performed on the output of the frame configuration unit 111, that is, the case where the OFDM modulation processing is performed on the signal having the frame configuration as shown in FIG. 2 has been described. Is not limited to this, but the point is that when transmitting a transmission signal including an error correction method information signal and a modulation method information signal by orthogonal frequency division multiplexing, the error correction method information signal and the modulation method information signal are discretely transmitted. The effect similar to that of the above-described embodiment can be obtained if the subcarriers are arranged at different positions in time or different subcarriers.

  INDUSTRIAL APPLICABILITY The present invention is useful when applied to a communication system adapted to adaptively switch the modulation method and error correction method according to the state of the propagation path to improve propagation path error tolerance.

The block diagram which shows the structure of the transmitter which concerns on Embodiment 1 of this invention. The figure which shows the transmission frame structure by Embodiment 1. FIG. IQ plan view for explanation in the case of QPSK modulation of modulation method information IQ plan view for explanation when error correction method information is BPSK modulated The block diagram which shows the structure of the receiver which concerns on Embodiment 1 of this invention. Block diagram showing the configuration of the modulation scheme / error correction scheme estimator Graph showing received signal strength of received signal when it receives fading or propagation path fluctuation FIG. 9 is a block diagram showing a configuration of a transmission apparatus according to Embodiment 2. Schematic diagram showing signal arrangement in an OFDM signal according to Embodiment 2 FIG. 8 is a block diagram showing a configuration of a receiving apparatus that receives and demodulates an OFDM signal transmitted from the transmitting apparatus of FIG. A diagram showing a conventional transmission frame configuration

Explanation of symbols

100, 800 Transmitter 103 Digital signal selector 104 Modulation scheme / error correction scheme determination section 105 Control information modulator 106 Transmission baseband signal selector 111 Frame configuration section 500, 1000 Receiver 507 Modulation scheme / error correction scheme estimation section 508 Reception digital signal selection unit 509 Signal selection unit 520 Modulation method / error correction method signal detection unit 523 Modulation method / error correction method information X reception power calculation unit 524 Modulation method / error correction method information Y reception power calculation unit 525 Modulation method / error Correction method decision section

Claims (2)

A transmission device configured to control and switch modulation methods and / or error correction methods to form information symbols,
Modulation scheme information signal generating means for generating an information signal related to the modulation scheme of the information symbol;
An error correction method information signal generating means for generating an information signal related to an error correction method of the information symbol;
A frame forming means for forming a transmission frame by arranging an information signal related to the modulation scheme of the information symbol and / or an information signal related to the error correction scheme of the information symbol in a plurality of symbols in the same frame;
A transmission apparatus comprising: transmission means for transmitting the transmission frame. A transmission method adapted to switch information between modulation methods and / or error correction methods to form information symbols,
A modulation scheme information signal generation step for generating an information signal related to the modulation scheme of the information symbol;
An error correction method information signal generating step for generating an information signal related to an error correction method of the information symbol;
A frame forming step of forming a transmission frame by arranging information signals related to the modulation scheme of the information symbols and / or information signals related to the error correction scheme of the information symbols in a plurality of symbols in the same frame;
A transmission method comprising: a transmission step of transmitting the transmission frame.

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