JP2004328793A - Transmission device, reception device, and communication method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To flexibly cope with improvement in data transmission efficiency and data quality.
SOLUTION: A frame configuration determining unit 101 determines a communication state based on transmission path information indicating a degree of fluctuation of a transmission path due to fading and data transmission rate information indicating a transmission rate of transmission data based on a received signal level. Judgment is made and the insertion interval of the known pilot symbol and the modulation scheme of the transmission digital signal are determined. Quadrature baseband modulating section 102 modulates a transmission digital signal into a quadrature baseband signal using the modulation scheme specified by frame configuration determining section 101. Pilot symbol generation section 103 generates a pilot symbol known between transmission and reception. Frame forming section 104 inserts a known pilot symbol output from pilot symbol generating section 103 into an output signal of orthogonal baseband modulating section 102 at an insertion interval instructed by frame configuration determining section 101 to form a frame. I do.
[Selection diagram] Fig. 1

Description

  The present invention relates to a transmitting device, a receiving device, and a communication method used for digital wireless communication.

  Conventionally, a technique described in Japanese Patent Application Laid-Open No. 1-196924 is known as a digital modulation method. This is a frame configuration in which one known pilot symbol is inserted for every N data symbols on the transmitting side. Then, on the receiving side, the frequency offset and the amount of amplitude distortion are estimated using the pilot symbols, and demodulated after removing them.

  Here, in wireless communication, fluctuations in the transmission path due to fading occur, and especially in land mobile communication, fluctuations in the transmission path are not uniform. When transmission line fluctuations are severe, it is necessary to shorten the insertion interval of pilot symbols to prevent the deterioration of the error rate of data demodulation. The demodulation error rate does not degrade significantly.

  Also, when the received signal level on the receiving side is low, the information symbols need to have a modulation scheme with high error resilience. Conversely, when the receiving signal level on the receiving side is high, the information symbols must prioritize a modulation scheme with good transmission efficiency. Can be.

  However, in the above-mentioned conventional digital modulation method, the insertion interval of pilot symbols and the modulation method of information symbols are fixed. Therefore, when the transmission path fluctuates greatly or when the reception signal level of the receiver is small, the error tolerance of data demodulation is reduced and the data quality is degraded. On the other hand, when the transmission path fluctuates slowly or when the received signal level on the receiving side is large, the data transmission efficiency cannot be improved despite the excessive data quality.

  The present invention has been made in view of the above, and an object of the present invention is to provide a transmission device, a reception device, and a communication method that can flexibly cope with an improvement in data transmission efficiency and an improvement in data quality. .

  According to the communication method of the present invention, a second symbol which is a pilot symbol is regularly inserted into a first symbol which is a multi-level modulation symbol, and a third symbol is inserted immediately before and after the second symbol. In the above, a signal point arrangement of the first symbol, the second symbol, and the third symbol is different, and a method of switching a modulation scheme of the first symbol according to a communication situation is adopted.

  A transmitting apparatus according to the present invention comprises: a first symbol generating unit that modulates a transmission digital signal to generate a first symbol that is an orthogonal baseband signal; and a second symbol generating unit that generates a pilot symbol that is an orthogonal baseband signal. Third symbol generation means for generating a third symbol arranged immediately before and after the second symbol which is an orthogonal baseband signal, frame configuration determination means for determining a modulation scheme of the first symbol based on communication conditions, A frame configuration unit that configures a frame of the communication scheme determined by the frame configuration determination unit, wherein signal point arrangements of the first symbol, the second symbol, and the third symbol are different in a signal space diagram. Take.

  A receiving apparatus of the present invention extracts a second symbol from a signal transmitted from a transmitting apparatus, and estimates a transmission path distortion amount from a reception state of the second symbol, and a transmission path distortion estimating unit. And a detecting means for detecting the first symbol and the second symbol based on the detected signal and outputting a received digital signal.

  According to the present invention, data transmission is performed by changing the insertion interval of known pilot symbols, BPSK modulation symbols or QPSK modulation symbols, and the information symbol modulation method in accordance with communication conditions such as transmission path fluctuations and received signal levels. It is possible to achieve both improvement in efficiency and improvement in data quality.

  The gist of the present invention is that a known pilot symbol, a binary phase shift keying (BPSK) modulation symbol or a quadrature phase (QPSK: Quadrature Phase Shift Keying) modulation symbol is used in accordance with communication conditions such as fluctuation of a transmission path and a received signal level. And the modulation method of the information symbol.

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

(Embodiment 1)
Embodiment 1 describes a digital wireless communication method in which the interval at which known pilot symbols are inserted and the modulation scheme of information symbols are changed according to communication conditions.

  FIG. 1 is a block diagram showing a configuration of the transmitting apparatus according to the present embodiment. As shown in FIG. 1, a transmitting apparatus according to the present embodiment includes a frame configuration determining section 101, an orthogonal baseband modulation section 102, a pilot symbol generation section 103, a frame configuration section 104, an LPF (Low Pass Filter). ) 105, 106, a transmission radio section 107, and a transmission antenna 108.

  The frame configuration determining unit 101 determines a communication state based on transmission path information indicating the degree of fluctuation of the transmission path due to fading and data transmission rate information indicating the transmission rate of transmission data based on the received signal level. A pilot symbol insertion interval and a transmission digital signal modulation method are determined. Then, frame configuration determining section 101 outputs a signal indicating the determined modulation scheme to orthogonal baseband modulation section 102, and outputs a signal indicating the determined insertion interval of known pilot symbols to frame forming section 104. The details of the frame configuration determining method in the frame configuration determining unit 101 will be described later.

  Here, when the same frequency band is used for the uplink and the downlink, the fluctuation state of the transmission path due to fading is determined by the communication side on which the transmission apparatus shown in FIG. The reception level of the transmitted modulated signal is measured, and can be estimated from the transition of the measurement result. Further, in the receiving apparatus which is the communication partner of the transmitting apparatus shown in FIG. 1, the reception level of the modulated signal transmitted from the communication partner is measured, and the fluctuation state of the transmission path due to fading is estimated based on the transition of the measurement result. By doing so, the transmission apparatus shown in FIG. 1 can recognize the fluctuation state of the transmission path due to fading.

  When the same frequency band is used for the uplink and the downlink, the transmission speed of the transmission data is transmitted from the communication partner on the receiving side (not shown) of the communication apparatus equipped with the transmitting apparatus shown in FIG. The reception level of the modulated signal can be measured and determined from the measurement result. Further, in the receiving device which is the communication partner of the transmitting device shown in FIG. 1, by measuring the reception level of the modulated signal transmitted from the communication partner, and determining the transmission speed of the transmission data based on the measurement result, The transmission device shown in FIG. 1 can recognize the transmission speed of transmission data.

  Quadrature baseband modulating section 102 modulates the transmission digital signal into a quadrature baseband signal using the modulation scheme specified by frame configuration determining section 101, and outputs the in-phase and quadrature components of the quadrature baseband signal to frame forming section 104. .

  Pilot symbol generation section 103 generates a pilot symbol known between transmission and reception, and outputs the in-phase component and the quadrature component of the known pilot symbol to frame configuration section 104.

  Frame forming section 104 inserts a known pilot symbol output from pilot symbol generating section 103 into an output signal of orthogonal baseband modulating section 102 at an insertion interval instructed by frame configuration determining section 101 to form a frame. I do.

  LPF 105 passes only a predetermined frequency band portion of the in-phase component output from frame forming section 104. LPF 106 allows only a predetermined frequency band portion of the orthogonal component output from frame forming section 104 to pass.

  After performing radio processing on the output signals of LPF 105 and LPF 106, transmission radio section 107 transmits a radio frequency signal as a radio wave from transmission antenna 108.

  Next, an example of a frame configuration determining method in the frame configuration determining section 101 of the transmitting apparatus shown in FIG. 1 will be described.

  FIG. 2 is a diagram illustrating an example of a frame configuration of a signal transmitted from the transmitting apparatus according to the present embodiment, and illustrates a time-symbol relationship. (201) is a frame configuration when the modulation scheme of information symbols is 16-quadrature amplitude modulation (16QAM) and the interval between known pilot symbols is N symbols. (202) is a frame configuration when the modulation scheme of information symbols is 16 QAM and the interval between known pilot symbols is M symbols. (203) is a frame configuration when the modulation scheme of information symbols is 8 phase shift keying (8PSK) and the interval between known pilot symbols is N symbols. (204) is a frame configuration when the modulation scheme of information symbols is 8PSK modulation and the interval between known pilot symbols is M symbols. At this time, N <M.

  The frame configuration determining unit 101 selects any one of (201), (202), (203), and (204) in FIG. 2 as the optimum frame configuration based on the transmission path information and the requested data transmission rate information.

  For example, in the case of high-speed fading, the frame configuration determining unit 101 sets the insertion interval of the known pilot symbol in order to maintain the data quality by sacrificing the data transmission efficiency at the receiving side, preventing the error rate of data demodulation from deteriorating. Either (201) or (203) of FIG. 2 is selected to make the frame narrow. On the other hand, in the case of low-speed fading, the frame configuration determining section 101 sets the frame configuration of either (202) or (204) in FIG. 2 so as to increase the insertion interval of known pilot symbols in order to improve data transmission efficiency. Select

  Further, when the received signal level is high, the frame configuration determining unit 101 gives priority to data transmission efficiency on the receiving side, and sets 16QAM as a modulation scheme of information symbols to either (201) or (202) in FIG. Select a frame configuration. On the other hand, when the received signal level is low, the frame configuration determining unit 101 gives priority to enhancing error resilience at the expense of data transmission efficiency on the receiving side, and sets 8PSK as the information symbol modulation method in FIG. The frame configuration of either (203) or (204) is selected.

  FIG. 3 shows a signal point arrangement of a 16QAM modulation scheme and a signal point arrangement of a known pilot symbol on an in-phase I-quadrature Q plane. A signal point 301 is a signal point of a known pilot symbol, and a signal point 302 is a signal point 302 of a 16QAM modulation. This is the signal point of the symbol. FIG. 4 shows the signal point arrangement of the 8PSK modulation scheme and the signal point arrangement of the known pilot symbol on the in-phase I-quadrature Q plane. The signal point 401 is the signal point of the known pilot symbol, and the signal point 402 is the 8PSK modulation. This is the signal point of the symbol.

  FIG. 5 is a block diagram showing a configuration of the receiving apparatus according to the present embodiment. As shown in FIG. 5, the receiving apparatus according to the present embodiment mainly includes a receiving antenna 501, a receiving radio section 502, a transmission path distortion estimating section 503, and a detecting section 504.

  Receiving radio section 502 receives a radio signal received by receiving system antenna 501, performs predetermined radio processing, and outputs an in-phase component and a quadrature component of a received quadrature baseband signal.

  The transmission path distortion estimating unit 503 receives the in-phase component and the quadrature component of the orthogonal baseband signal as input, extracts the signal of the known pilot symbol shown in FIGS. 3 and 4, and determines the transmission path distortion from the reception state of the known pilot symbol. The amount is estimated, and the transmission line distortion amount is output to the detector 504.

  Detector 504 receives the in-phase component and the quadrature component of the quadrature baseband signal as input, detects information symbols based on the amount of channel distortion, and outputs a received digital signal.

  As described above, by changing the insertion interval of known pilot symbols and the modulation scheme of information symbols in accordance with communication conditions such as transmission path fluctuations and received signal levels, it is possible to improve data transmission efficiency and data quality at the same time. Can be planned.

  In the present embodiment, two types of known pilot symbol insertion intervals have been described, but the present invention is not limited to this. Further, in the present embodiment, two types of modulation schemes for information symbols, 16QAM and 8PSK modulation, have been described, but the present invention is not limited to this.

  Further, in the present embodiment, the description has been given of the frame configuration of only the information symbols and the known pilot symbols shown in FIG. 2, but the synchronization symbol for adjusting the timing of the time between the transmitter and the receiver and the error correction on the receiver side are corrected. The present invention is not limited to a frame configuration composed of only information symbols and known pilot symbols, since a frame configuration in which a signal such as a symbol for inserting a symbol is inserted is also conceivable.

(Embodiment 2)
In the second embodiment, a digital wireless communication method will be described in which the interval at which BPSK modulation symbols are inserted and the modulation scheme of information symbols other than the BPSK modulation symbols are changed according to the communication situation.

  FIG. 6 is a block diagram showing a configuration of the transmitting apparatus according to the present embodiment. In the transmitting apparatus shown in FIG. 6, the same components as those of the transmitting apparatus shown in FIG.

  In the transmitting apparatus of FIG. 6, the operation of frame configuration determining section 601 differs from that of frame configuration determining section 101 of FIG. 6 employs a configuration in which a BPSK symbol modulation section 602 is added instead of pilot symbol generation section 103 as compared with FIG.

  The frame configuration determining unit 601 determines the communication status, determines the insertion interval of the BPSK modulation symbol and the modulation method of the transmission digital signal, outputs a signal indicating the determined modulation method to the orthogonal baseband modulation unit 102, and determines the signal. A signal indicating the insertion interval of the BPSK modulation symbol is output to orthogonal baseband modulation section 102, BPSK symbol modulation section 602, and frame configuration section 104.

  BPSK symbol modulation section 602 performs BPSK modulation on the transmission digital signal at the timing instructed by frame configuration determination section 601, and outputs the in-phase and quadrature components of the BPSK modulation symbol to frame configuration section 104.

  FIG. 7 is a diagram illustrating an example of a frame configuration of a signal transmitted from the transmitting apparatus according to the present embodiment, and illustrates a time-symbol relationship. (701) is a frame configuration when the modulation scheme of information symbols is 16 QAM and the interval between BPSK modulation symbols is N symbols. (702) is a frame configuration when the modulation scheme of information symbols is 16 QAM and the interval between BPSK modulation symbols is M symbols. (703) is a frame configuration when the modulation scheme of information symbols is 8PSK modulation and the interval between BPSK modulation symbols is N symbols. (704) is a frame configuration when the modulation scheme of information symbols is 8PSK modulation and the interval between BPSK modulation symbols is M symbols. At this time, N <M.

  The frame configuration determining unit 601 selects one of (701), (702), (703), and (704) in FIG. 7 as the optimum frame configuration based on the transmission path information and the requested data transmission rate information.

  For example, in the case of high-speed fading, the frame configuration determination unit 601 sets the insertion interval of the BPSK modulation symbol in order to maintain the data quality by sacrificing the data transmission efficiency on the receiving side, preventing the error rate of data demodulation from deteriorating. Either (701) or (703) of FIG. 7 is selected so as to make the frame narrower. On the other hand, in the case of low-speed fading, frame configuration determining section 601 increases the frame interval of either (702) or (704) in FIG. 7 so as to increase the insertion interval of BPSK modulation symbols in order to improve data transmission efficiency. Select

  Further, when the received signal level is large, the frame configuration determining unit 601 gives priority to data transmission efficiency on the receiving side, and uses 16QAM as the information symbol modulation method, either (701) or (702) in FIG. Select a frame configuration. On the other hand, when the received signal level is small, the frame configuration determining unit 601 gives priority to enhancing error resilience at the expense of data transmission efficiency on the receiving side, and sets 8PSK as the information symbol modulation method in FIG. 703) or (704) is selected.

  FIG. 8 shows a signal point arrangement of a 16QAM modulation scheme and a signal point arrangement of a BPSK modulation symbol on an in-phase I-quadrature Q plane. A signal point 801 is a BPSK modulation symbol, and a signal point 802 is a signal point of a 16QAM modulation symbol. Signal point. FIG. 9 shows the signal point arrangement of the 8PSK modulation scheme and the signal point arrangement of the BPSK modulation symbol on the in-phase I-quadrature Q plane. The signal point 901 is the signal point of the BPSK modulation symbol, and the signal point 902 is the signal point of the 8PSK modulation symbol. Signal point.

  FIG. 10 is a block diagram showing a configuration of the receiving apparatus according to the present embodiment. In the receiving apparatus shown in FIG. 10, the same components as those of the receiving apparatus shown in FIG. 5 are denoted by the same reference numerals as in FIG. 5, and description thereof will be omitted.

  In the receiving apparatus of FIG. 10, the operation of the transmission line distortion estimator 1001 is different from that of the transmission line distortion estimator 503 of FIG. 5, and the operation of the detector 1002 is different from that of the detector 504 of FIG.

  The transmission path distortion estimating section 1001 receives the in-phase component and the quadrature component of the orthogonal baseband signal as input, extracts the signal of the BPSK modulation symbol shown in FIG. 8 and FIG. 9, and calculates the transmission path distortion from the reception state of the BPSK modulation symbol. The amount is estimated, and the transmission line distortion amount is output to the detector 1002.

  Detector 1002 receives in-phase and quadrature components of the quadrature baseband signal as input, detects information symbols and BPSK modulation symbols based on the amount of transmission line distortion, and outputs a received digital signal.

  As described above, in the present embodiment, the transmission rate can be improved as compared with Embodiment 1 by inserting BPSK modulation symbols instead of known pilot symbols and sending information.

  In the present embodiment, two types of BPSK modulation symbol insertion intervals have been described, but the present invention is not limited to this. Further, in the present embodiment, two types of modulation schemes for information symbols, 16QAM and 8PSK modulation, have been described, but the present invention is not limited to this.

  Further, although the present embodiment has been described with reference to the frame configuration including only the information symbols and the BPSK modulation symbols shown in FIG. 7, the present invention is not limited to this frame configuration.

(Embodiment 3)
Embodiment 3 describes a digital wireless communication method in which the interval at which QPSK modulation symbols are inserted and the modulation scheme of information symbols other than the QPSK modulation symbols are changed according to the communication situation.

  FIG. 11 is a block diagram showing a configuration of the transmitting apparatus according to the present embodiment. In the transmitting apparatus shown in FIG. 11, the same components as those of the transmitting apparatus shown in FIG. 1 are denoted by the same reference numerals as those in FIG. 1, and description thereof is omitted.

  In the transmitting apparatus of FIG. 11, the operation of frame configuration determining section 1101 is different from that of frame configuration determining section 101 of FIG. Also, the transmission apparatus in FIG. 11 employs a configuration in which a QPSK symbol modulation section 1102 is added instead of pilot symbol generation section 103 as compared with FIG.

  The frame configuration determining unit 1101 determines the communication status, determines the insertion interval of the QPSK modulation symbol and the modulation method of the transmission digital signal, outputs a signal indicating the determined modulation method to the orthogonal baseband modulation unit 102, and determines the signal. A signal indicating the insertion interval of the QPSK modulation symbol is output to orthogonal baseband modulation section 102, QPSK symbol modulation section 1102, and frame configuration section 104.

  QPSK symbol modulation section 1102 performs QPSK modulation on the transmission digital signal at the timing instructed by frame configuration determination section 1101, and outputs the in-phase and quadrature components of the QPSK modulation symbol to frame configuration section 104.

  FIG. 12 is a diagram illustrating an example of a frame configuration of a signal transmitted from the transmitting apparatus according to the present embodiment, and illustrates a time-symbol relationship. (1201) is a frame configuration when the modulation scheme of information symbols is 16 QAM and the interval between QPSK modulation symbols is N symbols. (1202) is a frame configuration when the modulation scheme of information symbols is 16 QAM and the interval between QPSK modulation symbols is M symbols. (1203) is a frame configuration when the modulation scheme of information symbols is 8PSK modulation and the interval between QPSK modulation symbols is N symbols. (1204) is a frame configuration when the modulation scheme of information symbols is 8PSK modulation and the interval between QPSK modulation symbols is M symbols. At this time, N <M.

  The frame configuration determining unit 1101 selects one of (1201), (1202), (1203), and (1204) in FIG. 12 as the optimum frame configuration based on the transmission path information and the requested data transmission rate information.

  For example, in the case of high-speed fading, the frame configuration determining unit 1101 sets the insertion interval of the QPSK modulation symbol in order to maintain the data quality by sacrificing the data transmission efficiency at the receiving side, preventing the deterioration of the data demodulation error rate, and maintaining the data quality. Either (1201) or (1203) of FIG. 12 is selected to make the frame narrow. On the other hand, in the case of low-speed fading, frame configuration determining section 1101 increases the frame interval of either (1202) or (1204) of FIG. 12 so as to increase the insertion interval of QPSK modulation symbols in order to improve data transmission efficiency. Select

  Further, when the received signal level is large, the frame configuration determining section 1101 gives priority to data transmission efficiency on the receiving side, and uses 16QAM as the information symbol modulation method, either (1201) or (1202) in FIG. Select a frame configuration. On the other hand, when the received signal level is small, the frame configuration determining unit 1101 gives priority to enhancing error resilience at the expense of data transmission efficiency on the receiving side, and sets 8PSK as the information symbol modulation method in FIG. 1203) or (1204).

  FIG. 13 shows the signal point constellation of the 16QAM modulation scheme and the signal point constellation of the QPSK modulation symbol on the in-phase I-quadrature Q plane. Signal point. FIG. 14 shows a signal point arrangement of the 8PSK modulation scheme and a signal point arrangement of the QPSK modulation symbol on the in-phase I-quadrature Q plane. A signal point 1401 is a signal point of the QPSK modulation symbol, and a signal point 1402 is a signal point of the 8PSK modulation symbol. Signal point.

  FIG. 15 is a block diagram showing a configuration of the receiving apparatus according to the present embodiment. In the receiving apparatus shown in FIG. 15, the same components as those of the receiving apparatus shown in FIG. 5 are denoted by the same reference numerals as in FIG. 5, and description thereof will be omitted.

  In the receiving apparatus of FIG. 15, the operation of the transmission line distortion estimator 1501 is different from that of the transmission line distortion estimator 503 of FIG. 5, and the operation of the detector 1502 is different from that of the detector 504 of FIG.

  The channel distortion estimating section 1501 receives the in-phase component and the quadrature component of the quadrature baseband signal as input, extracts the QPSK modulation symbol signal shown in FIGS. 13 and 14, and determines the channel distortion from the reception state of the QPSK modulation symbol. The amount is estimated, and the amount of transmission line distortion is output to the detector 1502.

  Detection section 1502 receives the in-phase component and the quadrature component of the quadrature baseband signal as input, detects information symbols and QPSK modulation symbols based on the amount of transmission path distortion, and outputs a received digital signal.

  As described above, in the present embodiment, the transmission rate can be improved as compared with Embodiments 1 and 2 by inserting QPSK modulation symbols instead of known pilot symbols and transmitting information. .

  Although the present embodiment has been described with respect to two types of QPSK modulation symbol insertion intervals, the present invention is not limited to this. Further, in the present embodiment, two types of modulation schemes for information symbols, 16QAM and 8PSK modulation, have been described, but the present invention is not limited to this.

  Although the present embodiment has been described with reference to the frame configuration including only the information symbols and the QPSK modulation symbols shown in FIG. 12, the present invention is not limited to this frame configuration.

(Embodiment 4)
In the fourth embodiment, the modulation scheme of the information symbol is changed according to the communication situation, and when the modulation scheme of the information symbol is eight or more, the insertion interval is switched according to the communication situation to insert a known pilot symbol. The wireless communication method will be described.

  FIG. 16 is a block diagram showing a configuration of the transmitting apparatus according to the present embodiment. In the transmitting device shown in FIG. 16, the same components as those of the transmitting device shown in FIG.

  In the transmitting apparatus of FIG. 16, the operation of frame configuration determining section 1601 is different from that of frame configuration determining section 101 of FIG.

  Frame configuration determining section 1601 determines the modulation scheme of the transmission digital signal based on the communication status, and outputs a signal indicating the determined modulation scheme to orthogonal baseband modulation section 102. Also, when the determined modulation scheme is eight or more values, frame configuration determining section 1601 determines a pilot symbol insertion interval based on the communication status, and outputs a signal indicating the determined pilot symbol insertion interval to frame configuration section 104. Output to Further, when the determined modulation scheme is less than eight values, frame configuration determining section 1601 outputs a signal instructing stop of pilot symbol generation to pilot symbol generating section 103.

  Pilot symbol generation section 103 generates a pilot symbol known between transmission and reception, and outputs the in-phase component and the quadrature component of the known pilot symbol to frame configuration section 104. However, when a stop of pilot symbol generation is instructed from frame configuration determining section 1601, the operation is stopped.

  FIG. 17 is a diagram illustrating an example of a frame configuration of a signal transmitted from the transmitting apparatus according to the present embodiment, and illustrates a time-symbol relationship. (1701) is a frame configuration when the information symbol modulation method is BPSK. (1702) is a frame configuration when the modulation scheme of the information symbol is QPSK.

  In the frame configurations shown in FIG. 2 and FIG. 17, those having strong resistance to fading speed are (1701), (1702), (203), (201), (204), and (202) in order. Those having strong error rate tolerance are (1701), (1702), (203), (204), (201), and (202) in order. On the other hand, those having higher data transmission efficiency on the receiving side are (202), (201), (204), (203), (1702), and (1701) in order.

  The frame configuration determining unit 1601 determines the optimal frame configuration based on the transmission path information and the requested data transmission rate information in (201), (202), (203), and (204) of FIG. 2 or 17 (1701) and (1702) of FIG. Is selected.

  FIG. 18 shows a signal point arrangement of the BPSK modulation method on the in-phase I-quadrature Q plane, and a signal point 1801 is a signal point of a BPSK symbol. FIG. 19 shows a signal point arrangement of the QPSK modulation method on the in-phase I-quadrature Q plane, and a signal point 1901 is a signal point of a QPSK symbol.

  FIG. 20 is a block diagram showing a configuration of the receiving apparatus according to the present embodiment. In the receiving apparatus shown in FIG. 20, the same components as those of the receiving apparatus shown in FIG. 5 are denoted by the same reference numerals as in FIG. 5, and description thereof will be omitted.

  In the receiving apparatus of FIG. 20, the operation of the transmission line distortion estimating unit 2001 is different from that of the transmission line distortion estimating unit 503 in FIG.

  The transmission line distortion estimating unit 2001 receives the in-phase component and the quadrature component of the quadrature baseband signal as inputs and receives the pilot symbols shown in FIGS. 3 and 4 above, the BPSK modulation symbols shown in FIG. The transmission path distortion is estimated from the reception state of the QPSK modulation symbol, and the transmission path distortion is output to the detector 2002.

  Detector 2002 receives the in-phase component and the quadrature component of the quadrature baseband signal as input, detects information symbols based on the amount of channel distortion, and outputs a received digital signal.

  As described above, the modulation scheme of the information symbol is changed according to the communication conditions such as the fluctuation of the transmission path and the received signal level, and when the modulation scheme of the information symbol is a multi-level modulation scheme having eight or more values, a known pilot symbol is inserted. By changing the interval at which the known pilot symbols are inserted according to the communication conditions, it is possible to achieve both improvement in data transmission efficiency and improvement in data quality.

  Here, in the present embodiment, a configuration may be employed in which BPSK symbol modulation section 602 shown in FIG. 6 is provided instead of pilot symbol generation section 103 in the transmitting apparatus of FIG.

  In this case, frame configuration determining section 1601 determines the modulation scheme of the transmission digital signal based on the communication status. For example, the frame configuration determining unit 1601 selects one of (701), (702), (703), and (704) in FIG. 7 or (1701) and (1702) in FIG.

  Then, frame configuration determining section 1601 outputs a signal indicating the determined modulation scheme to orthogonal baseband modulation section 102. Further, when the determined modulation scheme is eight or more values, frame configuration determining section 1601 determines the insertion interval of the BPSK modulation symbol based on the communication condition, and outputs a signal indicating the determined insertion interval of the BPSK modulation symbol to the BPSK symbol. It outputs to modulation section 602 and frame configuration section 104. Further, when the determined modulation scheme is less than eight values, frame configuration determining section 1601 outputs to BPSK symbol modulating section 602 a signal instructing to stop generating BPSK modulated symbols.

  BPSK symbol modulation section 602 performs BPSK modulation on the transmission digital signal at the timing instructed by frame configuration determination section 1601, and outputs the in-phase and quadrature components of the BPSK modulation symbol to frame configuration section 104. However, when the frame configuration determining unit 1601 instructs to stop generating the BPSK modulation symbol, the operation is stopped.

  The transmission line distortion estimating unit 2001 receives the in-phase component and the quadrature component of the orthogonal baseband signal as inputs, and receives the BPSK modulation symbol shown in FIGS. 8 and 9 above, the BPSK modulation symbol shown in FIG. 18, or the BPSK modulation symbol shown in FIG. The transmission path distortion amount is estimated from the received state of the QPSK modulation symbol, and the transmission path distortion amount is output to the detector 2002.

  Further, the present embodiment may be configured such that transmission apparatus of FIG. 16 includes QPSK symbol modulation section 1102 shown in FIG. 11 instead of pilot symbol generation section 103.

  In this case, frame configuration determining section 1601 determines the modulation scheme of the transmission digital signal based on the communication status. For example, the frame configuration determining unit 1601 selects one of (1201) (1202) (1203) (1204) in FIG. 12 or (1701) (1702) in FIG.

  Then, frame configuration determining section 1601 outputs a signal indicating the determined modulation scheme to orthogonal baseband modulation section 102. Also, when the determined modulation scheme is eight or more values, frame configuration determining section 1601 determines the insertion interval of the QPSK modulation symbol based on the communication state, and outputs a signal indicating the determined insertion interval of the QPSK modulation symbol to the QPSK symbol. Output to modulation section 1102 and frame configuration section 104. Further, when the determined modulation scheme is less than eight values, frame configuration determining section 1601 outputs to QPSK symbol modulating section 1102 a signal instructing to stop generating QPSK modulated symbols.

  QPSK symbol modulation section 1102 performs QPSK modulation on the transmission digital signal at the timing instructed by frame configuration determination section 1601, and outputs the in-phase and quadrature components of the QPSK modulation symbol to frame configuration section 104. However, when the frame configuration determining unit 1601 instructs to stop generating QPSK modulated symbols, the operation is stopped.

  The transmission line distortion estimating unit 2001 receives the in-phase component and the quadrature component of the quadrature baseband signal as inputs and receives the QPSK modulation symbol shown in FIGS. 13 and 14 above, the BPSK modulation symbol shown in FIG. The transmission path distortion amount is estimated from the received state of the QPSK modulation symbol, and the transmission path distortion amount is output to the detector 2002.

  In the present embodiment, two types of known pilot symbol insertion intervals have been described, but the present invention is not limited to this. Further, in the present embodiment, two types of multi-level modulation schemes for information symbols of eight or more levels, 16QAM and 8PSK modulation, have been described, but the present invention is not limited to this.

  Further, in the present embodiment, the frame configurations of FIGS. 2, 7, 12, and 17 have been described, but the present invention is not limited to these frame configurations.

  Further, the BPSK modulation scheme and QPSK modulation scheme of the information symbol modulation scheme in the present invention are not limited to the signal point arrangements shown in FIGS. 18 and 19, and may be π / 2 shift BPSK modulation or π / 4 shift QPSK modulation. Absent.

(Embodiment 5)
In the fifth embodiment, the interval at which known pilot symbols are inserted, the number and signal point arrangement of each one symbol immediately before and after the known pilot symbol (hereinafter, referred to as “before and after pilot symbols”), and other than the symbols A digital wireless communication method for switching the modulation scheme of the information symbol will be described.

  FIG. 21 is a block diagram showing a configuration of the transmitting apparatus according to the present embodiment. In the transmitting device shown in FIG. 21, the same components as those in the transmitting device shown in FIG. 1 are denoted by the same reference numerals as in FIG. 1, and description thereof will be omitted.

  In the transmitting apparatus of FIG. 21, the operation of frame configuration determining section 2101 is different from that of frame configuration determining section 101 of FIG. Also, the transmitting apparatus of FIG. 21 employs a configuration in which a symbol modulation section 2102 before and after the pilot is added as compared with FIG.

  Frame configuration determining section 2101 determines the insertion interval of known pilot symbols and the modulation scheme of a transmission digital signal based on communication conditions. In this case, frame configuration determining section 2101 makes the modulation scheme different between the symbols before and after the pilot and other information symbols.

  Then, frame configuration determining section 2101 outputs a signal indicating the modulation scheme of the symbol before and after the pilot to pilot symbol modulation section 2102, and outputs a signal indicating the modulation scheme of the other information symbols to orthogonal baseband modulation section 102, A signal indicating the determined insertion interval of the known pilot symbol is output to pilot before and after symbol modulation section 2102 and frame configuration section 104.

  The pilot before and after symbol modulation section 2102 modulates the transmission digital signal with a predetermined modulation method at the timing instructed by the frame configuration determination section 2101, and outputs the in-phase component and the quadrature component of the pilot before and after symbols to the frame configuration section 104.

  FIG. 22 is a diagram illustrating an example of a frame configuration of a signal transmitted from the transmitting apparatus according to the present embodiment, and illustrates a time-symbol relationship. (2201) is a frame configuration when the modulation scheme of information symbols is 16 QAM and the interval between known pilot symbols is N symbols. (2202) is a frame configuration when the modulation scheme of information symbols is 16 QAM and the interval between known pilot symbols is M symbols. (2203) is a frame configuration when the modulation scheme of information symbols is 8PSK modulation and the interval between known pilot symbols is N symbols. (2204) is a frame configuration when the modulation scheme of information symbols is 8PSK modulation and the interval between known pilot symbols is M symbols. At this time, N <M.

  Signal point 2211 is one symbol immediately before the known pilot symbol when the modulation scheme of the information symbol is 16QAM, and signal point 2212 is one symbol immediately after the known pilot symbol when the modulation scheme of the information symbol is 16QAM. Signal point 2213 is one symbol immediately before the known pilot symbol when the information symbol modulation method is 8PSK modulation, and signal point 2214 is one symbol immediately after the known pilot symbol when the information symbol modulation method is 8PSK modulation. is there.

  The frame configuration determining unit 2101 selects one of (2201), (2202), (2203), and (2204) in FIG. 22 as the optimum frame configuration based on the transmission path information and the requested data transmission rate information.

  For example, in the case of high-speed fading, the frame configuration determination unit 2101 determines the insertion interval of the known pilot symbol in order to maintain the data quality while preventing the data transmission efficiency on the receiving side from deteriorating and reducing the error rate of data demodulation. Either (2201) or (2203) of FIG. 22 is selected so as to make the frame narrower. On the other hand, in the case of low-speed fading, the frame configuration determining section 2101 increases the frame interval of either (2202) or (2204) in FIG. 22 so as to increase the insertion interval of known pilot symbols in order to improve data transmission efficiency. Select

  When the received signal level is large, the frame configuration determining unit 2101 gives priority to data transmission efficiency on the receiving side and sets 16QAM as the information symbol modulation method, either (2201) or (2202) in FIG. Select a frame configuration. On the other hand, when the received signal level is small, the frame configuration determining unit 2101 gives priority to enhancing error resilience at the expense of data transmission efficiency on the receiving side, and sets 8PSK as the information symbol modulation scheme in FIG. 2203) or (2204).

  FIG. 23 shows a signal point constellation of the 16QAM modulation scheme, a signal point constellation of known pilot symbols, and a signal point constellation of symbols before and after the pilot in the in-phase I-quadrature Q plane. Signal point 2301 is a signal point of a known pilot symbol, signal point 2302 is a signal point of a 16QAM modulation symbol, and signal point 2303 is a signal point of a symbol before and after the pilot.

  FIG. 24 shows the signal point arrangement of the 8PSK modulation method, the signal point arrangement of known pilot symbols, and the signal point arrangement of symbols before and after the pilot on the in-phase I-quadrature Q plane. Signal points 2401, 2401-A and 2401-B are signal points of an 8PSK modulation symbol, 2401-A is a signal point of a known pilot symbol, and 2401-A and 2401-B are signal points of symbols before and after a pilot. , A straight line 2402 is a straight line connecting the signal point of the known pilot symbol and the origin on the in-phase I-quadrature Q plane.

  FIG. 25 is a block diagram showing a configuration of the receiving apparatus according to the present embodiment. In the receiving device shown in FIG. 25, the same components as those in the receiving device shown in FIG. 5 are denoted by the same reference numerals as in FIG. 5, and description thereof will be omitted.

  In the receiving apparatus of FIG. 25, the operation of the transmission line distortion estimator 2501 is different from that of the transmission line distortion estimator 503 of FIG. 5, and the operation of the detector 2502 is different from that of the detector 504 of FIG.

  The channel distortion estimating section 2501 receives the in-phase component and the quadrature component of the orthogonal baseband signal as input, extracts the signal of the known pilot symbol shown in FIGS. 23 and 24, and calculates the channel distortion from the reception state of the known pilot symbol. The amount is estimated, and the transmission line distortion amount is output to the detector 2502.

  Detector 2502 receives in-phase and quadrature components of the quadrature baseband signal as input, detects information symbols including symbols before and after the pilot based on the amount of channel distortion, and outputs a received digital signal.

  As described above, by changing the insertion interval of the known pilot symbol and the modulation method of the information symbol in accordance with the communication conditions such as the fluctuation of the transmission path and the received signal level, it is possible to improve the data transmission efficiency and the data quality at the same time. Can be planned.

  Further, as shown in FIGS. 23 and 24, by arranging two or more signal points of the symbols before and after the pilot on a straight line connecting the origin and the signal points of the known pilot symbols on the in-phase-orthogonal plane, In the receiving apparatus, even when symbol synchronization is not completely achieved when estimating the reference phase and the frequency offset amount from the pilot signal, it is possible to suppress deterioration in the estimation accuracy of the reference phase and the frequency offset amount due to the pilot symbols. Thereby, when the detection is performed by the detector 116, the bit error rate characteristics based on the carrier power to noise power ratio can be improved.

  Here, this embodiment can be combined with Embodiment 4 described above. That is, in FIG. 21, when the determined modulation scheme has eight or more values, frame configuration determining section 2101 determines a pilot symbol insertion interval based on the communication status, and outputs a signal indicating the determined pilot symbol insertion interval. Output to pilot before and after symbol modulation section 2102 and frame configuration section 104. Further, when the determined modulation scheme is less than eight values, frame configuration determining section 2101 outputs a signal instructing to stop the generation of pilot symbols to before and after pilot symbol modulating section 2102 and pilot symbol generating section 103.

  Pilot symbol generation section 103 generates a pilot symbol known between transmission and reception, and outputs the in-phase component and the quadrature component of the known pilot symbol to frame configuration section 104. However, when a stop of pilot symbol generation is instructed from frame configuration determining section 2101, the operation is stopped.

  The pilot before and after symbol modulation section 2102 performs BPSK modulation or QPSK modulation on the transmission digital signal at the timing instructed by the frame configuration determination section 2101, and outputs the in-phase and quadrature components of the pilot before and after symbols to the frame configuration section 104. However, when a stop of pilot symbol generation is instructed from frame configuration determining section 2101, the operation is stopped.

  Thus, the effect of the fourth embodiment can be obtained in addition to the effect of the present embodiment.

  In the present embodiment, two types of modulation schemes for information symbols, 16QAM and 8PSK modulation, have been described, but the present invention is not limited to this.

  Also, in the present embodiment, FIG. 22 has been described with the configuration of only information symbols, known pilot symbols, and symbols before and after pilot. However, the frame configuration of the present invention includes only information symbols, known pilot symbols, and symbols before and after pilot. The frame configuration is not limited to this.

  INDUSTRIAL APPLICABILITY The present invention is suitable for use in a transmitting device and a receiving device used for digital wireless communication.

FIG. 3 is a block diagram showing a configuration of a transmitting apparatus according to Embodiment 1 of the present invention. The figure which showed an example of the frame structure of the signal transmitted from the transmission apparatus of the said embodiment. Diagram of Signal Points of 16QAM and Known Pilot Symbols in In-Phase I-Quadrature Q Plane Signal Diagram of 8PSK Modulation and Known Pilot Symbol Signal Points on In-Phase I-Quadrature Q Plane FIG. 2 is a block diagram showing a configuration of a receiving apparatus according to the embodiment. FIG. 6 is a block diagram showing a configuration of a transmitting apparatus according to Embodiment 2 of the present invention. The figure which showed an example of the frame structure of the signal transmitted from the transmission apparatus of the said embodiment. Arrangement diagram of signal points of 16QAM and BPSK modulation on in-phase I-quadrature Q plane Arrangement diagram of signal points of 8PSK modulation and BPSK modulation on in-phase I-quadrature Q plane FIG. 2 is a block diagram showing a configuration of a receiving apparatus according to the embodiment. FIG. 9 is a block diagram showing a configuration of a transmitting apparatus according to Embodiment 3 of the present invention. The figure which showed an example of the frame structure of the signal transmitted from the transmission apparatus of the said embodiment. Arrangement diagram of signal points of 16QAM and QPSK modulation on in-phase I-quadrature Q plane Arrangement diagram of signal points of 8PSK modulation and QPSK modulation on in-phase I-quadrature Q plane FIG. 2 is a block diagram showing a configuration of a receiving apparatus according to the embodiment. FIG. 9 is a block diagram showing a configuration of a transmitting apparatus according to Embodiment 4 of the present invention. The figure which showed an example of the frame structure of the signal transmitted from the transmission apparatus of the said embodiment. Arrangement diagram of BPSK modulation signal points on in-phase I-quadrature Q plane Arrangement diagram of signal points of QPSK modulation on in-phase I-quadrature Q plane FIG. 2 is a block diagram showing a configuration of a receiving apparatus according to the embodiment. FIG. 14 is a block diagram showing a configuration of a transmitting apparatus according to Embodiment 5 of the present invention. The figure which showed an example of the frame structure of the signal transmitted from the transmission apparatus of the said embodiment. 16QAM in the In-phase I-Quadrature Q Plane, Known Pilot Symbols and Signal Points of Pre- and Post-Pilot Symbols 8PSK modulation on in-phase I-quadrature Q plane, arrangement diagram of signal points of known pilot symbols and symbols before and after pilot FIG. 2 is a block diagram showing a configuration of a receiving apparatus according to the embodiment.

Explanation of reference numerals

101, 601, 1101, 1601, 2101 Frame configuration determination unit 102 Orthogonal baseband modulation unit 103 Pilot symbol generation unit 104 Frame configuration unit 502 Radio reception unit 503, 1001, 1501, 2001 Transmission channel distortion estimation unit 504, 1002, 1502, 2002 Detector 602 BPSK symbol modulator 1102 QPSK symbol modulator 2102 Symbol modulator before and after pilot

Claims (17)

  A second symbol which is a pilot symbol is regularly inserted into a first symbol which is a multi-level modulation symbol, and a third symbol is inserted immediately before and after the second symbol, and the first symbol and the A communication method, wherein signal point arrangements of a second symbol and a third symbol are different, and a modulation scheme of the first symbol is switched according to a communication situation.   The communication method according to claim 1, wherein in the signal space diagram, the signal point of the third symbol is arranged on an imaginary line connecting the origin and the signal point of the second symbol.   First symbol generation means for modulating a transmission digital signal to generate a first symbol which is an orthogonal baseband signal, second symbol generation means for generating a pilot symbol which is an orthogonal baseband signal, and an orthogonal baseband signal. A third symbol generation unit for generating a third symbol arranged immediately before and after the second symbol, a frame configuration determination unit for determining a modulation scheme of the first symbol based on a communication condition, and a frame configuration determination unit. A frame configuration unit configured to configure a frame of the determined communication scheme, wherein a signal point arrangement of the first symbol, the second symbol, and the third symbol is different in a signal space diagram.   4. The transmitting apparatus according to claim 3, wherein in the signal space diagram, the signal point of the third symbol is arranged on an imaginary line connecting the origin and the signal point of the second symbol.   A second symbol, which is a pilot symbol, is inserted into a first symbol, which is a multi-level modulation symbol, and a modulation scheme of the first symbol is switched according to a communication condition, and an insertion interval of the second symbol is switched. Communication method.   Inserting a second symbol, which is a phase modulation symbol, into a first symbol, which is a multi-level modulation symbol, switching the modulation method of the first symbol according to communication conditions, and switching the insertion interval of the second symbol. Characteristic communication method.   The communication method according to claim 6, wherein the phase modulation method of the second symbol is binary phase modulation.   The transmitter transmits information using the second symbol, and the receiver estimates at least one of a transmission path distortion amount and a frequency offset amount using the second symbol. Or the communication method according to claim 7.   First symbol generation means for modulating a transmission digital signal to generate a first symbol which is an orthogonal baseband signal, second symbol generation means for generating a second symbol which is an orthogonal baseband signal for pilot symbols, Frame configuration determining means for determining the modulation scheme of the first symbol and determining the insertion interval of the second symbol on the basis of the above, and frame configuration means for configuring a frame of the communication scheme determined by the frame configuration determining means. A transmission device comprising:   First symbol generation means for modulating a transmission digital signal to generate a first symbol which is a quadrature baseband signal, and generating a second symbol for phase-modulating the transmission digital signal to generate a second symbol which is a quadrature baseband signal Means, frame configuration determining means for determining a modulation scheme of the first symbol based on communication conditions and determining an insertion interval of the second symbol, and forming a frame of the communication scheme determined by the frame configuration determining means. A transmission device comprising:   The transmission device according to claim 10, wherein the phase modulation method of the second symbol is binary phase modulation.   A transmission line distortion estimating means for extracting a second symbol from a signal transmitted from the transmitting device according to claim 10 or 11, and estimating a transmission line distortion amount from a reception state of the second symbol, and the transmission line. A receiving apparatus comprising: detecting means for detecting a first symbol and the second symbol based on a distortion amount and outputting a received digital signal.   A frequency offset amount estimating means for extracting a second symbol from a signal transmitted from the transmitting device according to claim 10 and estimating a frequency offset amount from a reception state of the second symbol, and the frequency offset amount. And a detection means for detecting the first symbol and the second symbol based on the detection signal and outputting a received digital signal.   A second symbol that is a pilot symbol is inserted into a first symbol that is a multi-level modulation symbol, and a third symbol is inserted immediately before and after the second symbol, and the first symbol and the second symbol are inserted in a signal space diagram. And a signal point arrangement of the third symbol is different, and a modulation method of the first symbol and an insertion interval of the second symbol are switched according to a communication situation.   15. The communication method according to claim 14, wherein in the signal space diagram, a signal point of the third symbol is arranged on an imaginary line connecting the origin and the signal point of the second symbol.   First symbol generation means for modulating a transmission digital signal to generate a first symbol which is an orthogonal baseband signal, second symbol generation means for generating a pilot symbol which is an orthogonal baseband signal, and an orthogonal baseband signal. Third symbol generation means for generating a third symbol arranged immediately before and after the second symbol, and a frame configuration for determining a modulation scheme of the first symbol and determining an insertion interval of the second symbol based on communication conditions Determining means, and frame configuring means for configuring a frame of the communication scheme determined by the frame configuration determining means, wherein signal points of the first symbol, the second symbol, and the third symbol are represented in a signal space diagram. A transmission device characterized by different arrangements.   17. The transmission device according to claim 16, wherein in the signal space diagram, the signal point of the third symbol is arranged on an imaginary line connecting the origin and the signal point of the second symbol.

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