JP3918830B2 - Transmission method and transmission apparatus - Google Patents

Description

  The present invention relates to a digital wireless communication system that performs wireless communication using pilot symbols.

A technique described in Patent Document 1 is known as a technique related to a digital radio communication system related to a conventional pilot symbol. This has a frame configuration as shown in FIG. 9, and a transmitting unit inserts one known pilot symbol for every N data symbols. The receiver uses the pilot symbols to estimate and demodulate the frequency offset and amplitude distortion amount.
JP-A-1-196924

  In wireless communication, transmission path fluctuations occur due to fading, but transmission path fluctuations are not uniform particularly in land mobile communications. When transmission path fluctuations are severe, it is necessary to shorten the pilot symbol insertion interval to prevent data demodulation errors. Conversely, when transmission path fluctuations are moderate, the pilot symbol insertion interval can be increased. In the conventional method, since the pilot symbol insertion interval is fixed to 1 symbol for every N data symbols, if priority is given to reducing data demodulation errors, the pilot symbol insertion rate must be increased. In this case, the data transmission efficiency is poor. On the other hand, when priority is given to improving the data transmission efficiency, the ratio of pilot symbol insertion is reduced, thereby increasing the number of data demodulation errors.

  In the present invention, the pilot symbol insertion interval is changed in accordance with communication conditions such as transmission path fluctuations and data quality, and the pilot symbol signal point arrangement in the in-phase-orthogonal plane is changed according to the pilot symbol insertion interval. It is an object of the present invention to provide a communication method that can flexibly cope with data transmission efficiency and data quality.

  In order to solve this problem, the present invention provides a transmission method for inserting a second symbol, which is a pilot symbol, into a first symbol, which is a multilevel modulation symbol, and an insertion interval of the second symbol according to a communication situation Is a transmission method for switching between.

  In the transmission method of the present invention, with the above-described configuration, the data demodulation is performed by shortening the insertion interval of known pilot symbols or PSK modulation symbols when fluctuations in the transmission path become severe or when it is desired to reduce demodulation errors of transmission data. When errors are reduced and transmission path fluctuations become moderate or when it is desired to increase data transmission efficiency, the data transmission efficiency can be increased by increasing the insertion interval of known pilot symbols or PSK modulation symbols.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

(Embodiment 1)
FIG. 1 is a conceptual diagram of a configuration of a wireless communication system according to the present embodiment. In FIG. 1, (a) is a transmission system and (b) is a reception system. In FIG. 1, 101 is a transmission digital signal, 102 is transmission path information, 103 is requested data transmission rate information, 104 is a transmission system quadrature baseband modulation unit, 105 is an in-phase component of a quadrature baseband signal, and 106 is a quadrature baseband signal. , 107 is a transmission radio unit, 108 is a transmission signal, 109 is a transmission system antenna, 110 is a reception system antenna, 111 is a reception radio unit, 112 is an in-phase component of the reception system quadrature baseband signal, and 113 is a reception system quadrature. An orthogonal component of the baseband signal, 114 is a transmission path distortion estimation section, 115 is a transmission path distortion estimation value, 116 is a quasi-synchronous detection section, and 117 is a received digital signal.

  FIG. 2 is a diagram showing an example of a frame configuration when the frame configuration of multi-level orthogonal modulation symbols of 8 values or more and known pilot symbols are switched in two stages.

  FIG. 3 shows an example of signal point arrangement of known pilot symbols in the in-phase I-orthogonal Q plane, and 301 shows signal points of known pilot symbols in the frame configuration of FIG. Reference numeral 302 denotes a signal point of a known pilot symbol in the frame configuration of FIG.

  FIG. 4 shows signal point arrangements in the in-phase I-orthogonal Q plane of the multilevel QAM modulation system of eight or more values and signal point arrangement of known pilot symbols, and 401 is a signal of a multilevel QAM modulation symbol of eight or more values. A point 402 is a signal point of a known pilot symbol.

  1 to 4, the known pilot symbol insertion interval is changed in accordance with the communication status in the scheme for inserting known pilot symbols in the multi-level modulation scheme of 8 or more values, and the known pilot symbols are changed. A digital wireless communication system that changes the signal point arrangement in the in-phase-orthogonal plane according to the insertion interval will be described.

  FIG. 1A shows a transmission system. A transmission digital signal 101, transmission path information 102, and requested data transmission rate information 103 are input to the orthogonal baseband unit 104, and the transmission path information 102 and requested data transmission rate information are displayed. The frame configuration is determined based on 103, and the in-phase component 105 of the quadrature baseband signal and the quadrature component 106 of the quadrature baseband signal are output. Then, the in-phase component 105 of the quadrature baseband signal and the quadrature component 106 of the quadrature baseband signal are input to the transmission radio unit 107, and the transmission radio unit 107 outputs the transmission signal 108, and a radio wave is output from the transmission system antenna 109. .

  FIG. 1B shows a reception system. The reception radio unit 111 receives a signal received by the reception system antenna 110 as an input, and outputs an in-phase component 112 of the reception quadrature baseband signal and an orthogonal component 113 of the reception quadrature baseband signal. Output. The transmission path distortion estimation unit 114 receives the in-phase component 112 of the quadrature baseband signal and the quadrature component 113 of the quadrature baseband signal as inputs, and outputs a transmission path distortion amount 115. The quasi-synchronous detection unit 116 receives the in-phase component 112 of the quadrature baseband signal and the quadrature component 113 of the quadrature baseband signal, performs quasi-synchronous detection based on the transmission path distortion amount 115, and outputs a received digital signal 117.

  FIG. 2 shows an example of a frame configuration of known pilot symbols and multi-level orthogonal modulation symbols of 8 or more values when switching frames in two stages based on transmission path information and requested data transmission rate. At this time, N <M.

  FIG. 3 shows the signal point arrangement of known pilot symbols in the in-phase I-orthogonal Q plane, and 301 is a signal point of known pilot symbols when the frame configuration of FIG. By placing signal points of known pilot symbols at 301 in the case of a), the most sensitive reception characteristic can be obtained. 302 is a signal point of a known pilot symbol when the frame configuration of FIG. 2 (b) is adopted. When the frame configuration is (b), the signal point of the known pilot symbol is arranged at 302, so that reception with the highest sensitivity is possible. Characteristics are obtained.

  In FIG. 1, when the transmission path information 102 is information that the fluctuation of the transmission path is severe, or when the requested data transmission rate information 103 is information that is not requested to improve the data transmission rate by another communication station, The frame configuration in FIG. 2A is used, and the signal point arrangement of the known pilot symbols is 301 in FIG. When the transmission path information 102 is information indicating that the fluctuation of the transmission path is moderate, or when the requested data transmission rate information 103 is information requested to improve the data transmission rate by another communication station, FIG. ) And the signal point arrangement of the known pilot symbols is 302 in FIG.

  In this way, a two-stage frame configuration is taken according to the transmission path conditions and data transmission rate requirements, and the signal point arrangement of the known pilot symbol signal points on the in-phase I-orthogonal Q plane is changed according to the frame configuration. By changing the pilot symbol signal point arrangement, a system capable of receiving with higher sensitivity can be configured compared to a system that does not change the known pilot symbol signal point arrangement even if the frame configuration is changed.

  Here, the method of switching the frame configuration in two stages as shown in FIG. 2 has been described, but the frame configuration and the number of stages to be switched are not limited to this.

  FIG. 4 shows the signal point arrangement of the multi-level QAM system with eight or more values on the in-phase I-orthogonal Q plane, and 401 shows the signal point of the multi-level QAM system with eight or more values. Among the signal points 401 of the multi-level QAM system having eight or more values, A, B, C, and D have the largest distance from the origin on the in-phase I-quadrature Q plane, and the value thereof is rQAM. Reference numeral 402 denotes a signal point of a known pilot symbol, which is arranged on the axis. At this time, if the distance of the signal point of the known pilot symbol from the origin is rPILOT, rPILOT can be made larger than rQAM without imposing a burden on the power amplifier of the transmission system.

  Here, the signal points of the known pilot symbols are arranged on the in-phase I-axis in the in-phase I-quadrature Q plane, but the same is true on the quadrature Q-axis.

  In the present embodiment, the multi-level QAM scheme having eight or more values has been described as the modulation scheme, but the same applies to the modulation schemes of the 64QAM scheme, the 32QAM scheme, and the 16QAM scheme.

  As described above, according to the present embodiment, in a method of inserting a known pilot symbol in a multi-level modulation scheme of 8 or more values, the known pilot symbol insertion interval is changed in accordance with the communication situation, and the known pilot symbol is changed. This is a digital wireless communication system that changes the signal point arrangement in the in-phase-orthogonal plane according to the insertion interval, and this makes it possible to reduce transmission data demodulation errors or when transmission path fluctuations become severe. Reduces the demodulation error of data by shortening the known pilot symbol insertion interval, and lengthens the known pilot symbol insertion interval when the fluctuation of the transmission path becomes slow or when it is desired to increase the data transmission efficiency. In addition, the data transmission efficiency can be increased. By changing the point arrangement according to the insertion interval, it is possible to receive data with higher sensitivity compared to a system in which the signal point arrangement of the known pilot symbols in the in-phase-orthogonal plane is constant, improving data transmission efficiency and data. This has the effect of enabling flexible measures to improve the quality of the product.

(Embodiment 2)
FIG. 1 illustrates a configuration concept of a wireless communication system according to the present embodiment. In FIG. 1, (a) is a transmission system and (b) is a reception system. In FIG. 1, 101 is a transmission digital signal, 102 is transmission path information, 103 is requested data transmission rate information, 104 is a transmission system quadrature baseband modulation unit, 105 is an in-phase component of a quadrature baseband signal, and 106 is a quadrature baseband signal. , 107 is a transmission radio unit, 108 is a transmission signal, 109 is a transmission system antenna, 110 is a reception system antenna, 111 is a reception radio unit, 112 is an in-phase component of the reception system quadrature baseband signal, and 113 is a reception system quadrature. An orthogonal component of the baseband signal, 114 is a transmission path distortion estimation section, 115 is a transmission path distortion estimation value, 116 is a quasi-synchronous detection section, and 117 is a received digital signal.

  FIG. 5 is a diagram showing an example of a frame configuration when switching the frame configuration of multi-level orthogonal modulation symbols of 8 values or more and PSK modulation symbols in two stages.

  FIG. 6 shows an example of signal point arrangement of 8PSK modulation symbols, which is an example of PSK modulation in the in-phase I-quadrature Q plane. Reference numeral 601 denotes a signal of 8PSK modulation symbols in the frame configuration of FIG. A point 602 indicates a signal point of an 8PSK modulation symbol in the frame configuration of FIG.

  FIG. 4 shows signal point arrangements in the in-phase I-orthogonal Q plane of the multilevel QAM modulation system with eight or more values, and 401 is a signal point of a multilevel QAM modulation symbol with eight or more values.

  FIG. 7 shows the signal point arrangement of the BPSK modulation method in the in-phase I-orthogonal Q plane, and reference numeral 701 denotes the signal point of the BPSK modulation method.

  FIG. 8 shows the signal point arrangement of the QPSK modulation method in the in-phase I-orthogonal Q plane, and 801 is the signal point of the QPSK modulation method.

  1, 4, 5, 6, 7, and 8, a PSK modulation symbol insertion interval in a system that inserts a PSK modulation symbol in an 8-level or higher multilevel modulation system. A digital wireless communication system that changes the signal point arrangement in the in-phase-orthogonal plane of the PSK modulation symbol in accordance with the insertion interval will be described.

  Since the operation and action of the wireless communication system shown in FIG. 1 are the same as those in (Embodiment 1), they are omitted.

  FIG. 5 shows an example of a frame configuration of a PSK modulation symbol and an 8-level or higher multi-level orthogonal modulation symbol when switching frames in two stages based on transmission path information and a required data transmission rate. At this time, N <M.

  FIG. 6 shows a signal point arrangement of 8PSK modulation symbols, which are an example of PSK modulation in the in-phase I-quadrature Q plane, and 601 is a signal point of 8PSK modulation symbols when the frame configuration of FIG. Thus, when the frame configuration is (a), the signal point of the 8PSK modulation symbol is arranged at 601 so that the reception characteristic with the highest sensitivity can be obtained. Reference numeral 602 denotes the signal point of the 8PSK modulation symbol when the frame configuration of FIG. 5B is adopted. When the frame configuration is (b), the signal point of the 8PSK modulation symbol is arranged at 602, so that reception with the highest sensitivity is possible. Characteristics are obtained.

  In FIG. 1, when the transmission path information 102 is information that the fluctuation of the transmission path is severe, or when the requested data transmission rate information 103 is information that is not requested to improve the data transmission rate by another communication station, The frame configuration shown in FIG. 5A is used, and the signal point arrangement of the 8PSK modulation symbol is 601 in FIG. When the transmission path information 102 is information indicating that the fluctuation of the transmission path is moderate, or when the requested data transmission rate information 103 is information requested to improve the data transmission rate by another communication station, FIG. ) And the signal point arrangement of the 8PSK modulation symbol is 602 in FIG.

  In this way, a two-stage frame configuration is taken according to the transmission path conditions and data transmission rate requirements, and the signal point arrangement of the 8PSK modulation symbol signal points on the in-phase I-orthogonal Q plane is changed according to the frame configuration. By changing the signal point arrangement of the modulation symbols, a system capable of receiving with higher sensitivity can be configured compared to a system that does not change the signal point arrangement of the 8PSK modulation symbols even if the frame configuration is changed.

  Here, the 8PSK modulation method has been described as an example of the PSK modulation method, but the present invention is not limited to this. Further, although the method of switching the frame configuration in two stages as shown in FIG. 5 has been described, the frame configuration and the number of stages to be switched are not limited to this.

  FIG. 4 shows the signal point arrangement of the multi-level QAM system with eight or more values on the in-phase I-orthogonal Q plane, and 401 shows the signal point of the multi-level QAM system with eight or more values. Among the signal points 401 of the multi-level QAM system having eight or more values, A, B, C, and D have the largest distance from the origin on the in-phase I-quadrature Q plane, and the value thereof is rQAM.

  FIG. 7 shows the signal point arrangement of the BPSK modulation method arranged on the in-phase I axis in the in-phase I-orthogonal Q plane, and 701 shows the signal point of the BPSK modulation method arranged on the in-phase I axis. At this time, if the distance from the origin to the signal point of the BPSK modulation method is rBPSK, rBPSK can be made larger than rQAM without imposing a burden on the power amplifier of the transmission system.

  Here, the signal points of the BPSK modulation method are arranged on the in-phase axis I in the in-phase I-quadrature Q plane, but the same is true on the quadrature Q-axis.

  FIG. 8 shows signal points of the QPSK modulation method arranged on the in-phase I and quadrature Q axes in the in-phase I-quadrature Q plane. At this time, the distance from the origin to the QPSK modulation method signal point is expressed as rQPSK. Then, rQPSK can be made larger than rQAM without imposing a burden on the power amplifier of the transmission system.

  In the present embodiment, the multi-level QAM scheme having eight or more values has been described as the modulation scheme, but the same applies to the modulation schemes of the 64QAM scheme, the 32QAM scheme, and the 16QAM scheme.

  As described above, according to the present embodiment, in the method of inserting a PSK modulation symbol in a multi-level modulation method of eight or more values, the PSK modulation symbol insertion interval is changed according to the communication situation, and the PSK modulation symbol is changed. This is a digital wireless communication system that changes the signal point arrangement in the in-phase-orthogonal plane according to the insertion interval, and this makes it possible to reduce transmission data demodulation errors or when transmission path fluctuations become severe. Reduces the data demodulation error by shortening the PSK modulation symbol insertion interval, and lengthens the PSK modulation symbol insertion interval when the fluctuation of the transmission path becomes slow or when it is desired to increase the data transmission efficiency. Therefore, the data transmission efficiency can be increased, and the signal point arrangement of the PSK modulation symbols in the in-phase-orthogonal plane can be adjusted to the insertion interval. Can be received with higher sensitivity compared to a system in which the signal point arrangement of PSK modulation symbols in the in-phase-orthogonal plane is fixed, and it is flexible to improve data transmission efficiency and data quality. This makes it possible to cope with the situation.

  The present invention is useful as a transmission method used for digital radio communication, for example.

The figure which shows the structure of the radio | wireless communications system by one embodiment of this invention. The figure which shows an example of the frame structure using the switching by one embodiment of this invention The figure which shows the signal point arrangement | positioning in the in-phase I-quadrature Q plane of the known pilot symbol using switching by one embodiment of this invention The figure which shows the signal point arrangement | positioning of the known pilot symbol which has arrange | positioned on the axis | shaft the signal point of 8 levels or more and the signal point in the in-phase I-quadrature Q plane by one embodiment of this invention The figure which shows an example of the frame structure using the switching by one embodiment of this invention The figure which shows the signal point arrangement | positioning in the in-phase I-quadrature Q plane of the 8PSK modulation symbol using switching by one embodiment of this invention The figure which shows the signal point arrangement | positioning of the BPSK modulation system which has arrange | positioned the signal point on the axis in the in-phase I-quadrature Q plane by one embodiment of this invention The figure which shows the signal point arrangement | positioning of the QPSK modulation system which has arrange | positioned the signal point on the axis in the in-phase I-quadrature Q plane by one embodiment of this invention The figure which shows an example of the frame structure of the signal transmitted conventionally.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Transmission digital signal 102 Transmission path information 103 Requested data transmission rate information 104 Transmission system orthogonal baseband modulation part 105 In-phase component of orthogonal baseband signal 106 Orthogonal component of orthogonal baseband signal 107 Transmission radio part 108 Transmission signal 109 Transmission system antenna 110 Reception system antenna 111 Reception radio section 112 In-phase component of reception system orthogonal baseband signal 113 Quadrature component of reception system orthogonal baseband signal 114 Transmission path distortion estimation section 115 Transmission path distortion amount estimated value 116 Quasi-synchronous detection section 117 Reception digital signal 301 Signal point of known pilot symbol 302 Signal point of known pilot symbol 401 Signal point of multi-level QAM system with 8 or more values 402 Signal point of known pilot symbol with signal points arranged on axis 601 Signal point of 8PSK modulation 602 8P Signal points of QPSK modulation scheme and the signal point 801 signal points of BPSK modulation scheme where the signal point 701 signal points of K modulation placed on the axis placed on the axis

Claims (4)

A transmission method for inserting a second symbol into a first symbol that is a multi-level modulation symbol, wherein the insertion interval of the second symbol is switched in accordance with information on a data transmission rate from a communication partner . A transmission method for inserting a second symbol into a first symbol that is a multi-level modulation symbol, wherein an insertion interval of the second symbol is switched according to a communication situation, and the second symbol is changed according to the insertion interval. A transmission method that changes the amplitude of the. A transmission apparatus used in a transmission method for inserting a second symbol into a first symbol that is a multi-level modulation symbol, wherein the insertion interval of the second symbol is switched according to information on a data transmission rate from a communication partner A transmission apparatus comprising an orthogonal baseband modulation unit that outputs orthogonal baseband signals of a first symbol and the second symbol. A transmission apparatus used in a transmission method for inserting a second symbol that is a phase modulation symbol into a first symbol that is a multilevel modulation symbol, wherein the insertion interval of the second symbol is switched according to a communication situation, and the insertion interval And a quadrature baseband modulation unit that outputs a quadrature baseband signal of the second symbol and the first symbol in which the amplitude of the second symbol is changed.

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