JP2009246609A - Encoder and transmitter, and decoder and receiver - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an encoder and a transmitter provided with the same for generating an encoded signal in order to highly reliably transmit important information, and to provide a decoder and a receiver provided with the same for decoding the encoded signal. <P>SOLUTION: The encoder 6a comprises mapping sections 61, 62, and an additional mapping section 63a for modulating input information. In the additional mapping section 63a, the number of bits of input information is less than that of the other mapping sections 61, 62. Consequently, the number of encoded signals obtained by modulating the information can be made smaller than that of signals output from the other mapping sections 61, 62. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an encoding apparatus that modulates information and outputs an encoded signal, and a transmission apparatus including the same. The present invention also relates to a decoding apparatus that obtains information by demodulating an encoded signal and a receiving apparatus including the same.

  In recent years, digital communication technology has been used in various fields of wireless communication such as television broadcasting and mobile communication. For example, it is also used in intelligent transport systems (ITS) that improve safety and convenience by communicating between a car and a car and a base station. A method of performing communication using a signal modulated by an OFDM (Orthogonal Frequency Division Multiplex) method is widely used.

  Signals communicated by such digital communication technology include information with relatively high importance such as control information and information with relatively low importance such as data information. Therefore, when transmitting such information, it is preferable that information having high importance is transmitted more accurately. For example, Non-Patent Document 1 proposes an encoding device that modulates information so that highly important information is transmitted relatively accurately.

  The configuration of this encoding apparatus will be described with reference to FIG. FIG. 9 is a block diagram showing a configuration of a conventional encoding device. As illustrated in FIG. 9, the encoding device 100 includes an S / P (Serial / Parallel) conversion unit 101 that rearranges input serial important information in parallel every two bits, and input serial non-critical information. Are rearranged in parallel every 4 bits, the information input from the S / P converter 101 and the S / P converter 102 is rearranged, and the 2-bit important information and the 4-bit An interleaver 103 that outputs non-important information as one symbol, and a mapping unit 104 that generates a coded signal by modulating a symbol output from the interleaver 103 are provided.

  Further, a modulation method of mapping section 104 shown in FIG. 9 will be described using FIG. FIG. 10 is a constellation (signal point arrangement diagram) illustrating a modulation method of a conventional encoding device. The constellation represents the phase and amplitude that can be taken by the encoded signal during modulation on a complex plane. The I (In-phase) axis represents the real component, and the Q (Quadrature-phase) axis represents the imaginary component. In addition, the mapping unit 104 modulates an input 6-bit symbol with 64QAM (Quadrature Amplitude Modulation).

  The symbols input to the mapping unit 104 are arranged at any of the 64 symbol positions S shown in FIG. At this time, it is determined which quadrant of the four quadrants to be assigned to the symbol position S based on the 2-bit important information. Further, based on 4-bit non-important information, it is determined which symbol position S of the 16 symbol positions S in one quadrant is to be allocated, thereby realizing 64QAM modulation. When this modulation method is expressed hierarchically, it can be expressed as a modulation method combining QPSK (Quadrature Phase Shift Keying) and 16QAM.

  If communication is performed using this encoded signal, important information can be demodulated based on the quadrant to which the received signal belongs when the encoded signal is demodulated in the decoding apparatus. Therefore, even if the symbol position S of the received signal is recognized as an incorrect position at the time of demodulation, the important information in the symbol can be accurately transmitted as long as it is in the same quadrant.

ETSI TR 102377 V1.2.1 (2005-11)

  However, if not only the symbol position but also the quadrant is erroneously recognized at the time of demodulation, there arises a problem that important information is recognized as erroneous. In particular, when applied to the above-described ITS, the communication state is likely to be inferior because it is used for communication of a mobile body such as a car. Therefore, even important information may not be transmitted correctly. Furthermore, since information that is important information is often information that must be transmitted correctly in terms of safety, it is required to be a communication method that is as robust as possible.

  In view of such a problem, the present invention provides an encoding device that creates an encoded signal for communicating important information with high reliability, a transmission device including the encoded signal, and a method for decoding the encoded signal. It is an object of the present invention to provide a decoding device and a receiving device including the same.

  In order to achieve the above object, an encoding apparatus according to the present invention is an encoding apparatus that modulates input information and outputs an encoded signal, and modulates input p-bit first information. A mapping unit that outputs one encoded signal, the q-bit first information, and r-bit second information that is higher in importance than the first information are input, and the second information And at least one additional mapping unit that modulates the first information and outputs an encoded signal, and the sum of q and r is smaller than p.

  Moreover, in the encoding apparatus having the above configuration, the additional mapping unit sets a phase difference of the encoded signal caused by the difference of the second information to be larger than a phase difference caused by the difference of the first information. It doesn't matter.

  If comprised in this way, the phase difference by the difference of comparatively important 2nd information will become large. Therefore, even if the phase of the encoded signal fluctuates due to transmission, the possibility that the second information is correctly demodulated on the receiving side can be kept high. That is, it is possible to make resistance against distortion during transmission of the second information higher than resistance against distortion during transmission of the first information. For example, when the second information is modulated by QPSK with such a configuration, the first information is not modulated by BPSK (Binary Phase Shift Keying). In this case, the first information is modulated by 8PSK (8 Phase Shift Keying), 16QAM, or the like.

  Further, in the encoding device having the above configuration, the additional mapping unit adds pq-r-bit third information to the first information and the second information, and the first information, the second information, and the second information And further comprising an information insertion unit that combines the third information into p-bit information, and the additional mapping unit modulates the p-bit information output from the information insertion unit and outputs an encoded signal. It does not matter.

  With this configuration, both the mapping unit and the additional mapping unit modulate p-bit information. Therefore, it is possible to have a configuration in which modulation is performed by the same modulation method. Therefore, it is possible to suppress the complexity of the configuration of the encoding device.

  In the encoding apparatus having the above configuration, the additional mapping unit may further include an information duplicating unit that duplicates the second information to obtain the third information. If comprised in this way, it will become possible to obtain 3rd information easily.

  In the encoding device having the above configuration, the additional mapping unit modulates the first information based on a first modulation unit that modulates the second information and a signal output from the first modulation unit. The second modulation unit that outputs the encoded signal may be provided.

  If comprised in this way, it will become possible to perform the same modulation | alteration as another mapping part by a simple method, without supplementing a missing bit. Therefore, it is possible to suppress the complexity of the configuration of the encoding device.

  Further, in the encoding device having the above configuration, when the modulation method by the additional mapping unit is represented on the constellation, two lattice point groups arranged in a lattice form in which the distance between adjacent points are equal to each other are predetermined. Are arranged so that the straight line is a symmetric axis, the centers of the lattice point groups are located on a straight line that is perpendicular to the symmetric axis and passes through the origin, and connects adjacent points in the lattice point group. It is also possible that all the lines consisting of are perpendicular or parallel to the axis of symmetry.

  With this configuration, when the center of the grid point, that is, when the average power is constant, the distance between the origin and the point closest to the origin is at least all lines connecting adjacent points in the grid point group. It becomes possible to make it larger than the case of forming an angle of 45 ° with the symmetry axis. Further, when there is no point at the center of the lattice, this arrangement method can maximize the distance between the origin and the point closest to the origin. Therefore, it is possible to increase the power of the encoded signal, which is the minimum power, and it is possible to further suppress errors. Further, when the position of the lattice group is determined based on the second information, it is preferable that the symmetry axis is the Q axis. In this case, the second information can be demodulated with the positive and negative of the real component, as in the case of modulation with BPSK. For this reason, it is possible to prevent the demodulation processing on the receiving side from becoming complicated.

  Further, the transmission apparatus of the present invention is a transmission apparatus that has a modulation function for modulating input information and transmits a signal based on an encoded signal obtained by the modulation function, and is a code that realizes the modulation function The encoding unit includes the above encoding device.

  The decoding apparatus of the present invention is a decoding apparatus that demodulates an input encoded signal and outputs information, and based on one input encoded signal, the p-bit first information is converted. Based on the output demapping unit and one input encoded signal, the q-bit first information and the r-bit second information having higher importance than the first information are output. At least one separate demapping unit that performs the summation of q and r to be smaller than p.

  Further, in the decoding device having the above configuration, the demultiplexing unit is configured to input the q-bit first information, the r-bit second information, and pq-r based on an input encoded signal. Of the information output from the first demapping unit, the first demapping unit that outputs information obtained by combining the third information of the bits, the first information, the second information, and the first information An information extraction unit that outputs three pieces of information separately, and an information deletion that outputs the second information by deleting the third information from the second information and the third information output from the information extraction unit May be further provided.

  If comprised in this way, since the information output from a 1st demapping part will be a p bit, it will become the same as another demapping part. Therefore, it is possible to have a configuration in which demodulation is performed using the same demodulation method as other demapping units. Therefore, it becomes possible to prevent the configuration of the decoding apparatus from becoming complicated.

  Also, in the decoding device having the above configuration, the separation demapping unit is configured to combine q-bit first information and r-bit second information based on an input encoded signal. A second demapping unit that outputs the information, and an information extraction unit that outputs the first information and the second information separately from the information output from the second demapping unit. It does not matter.

  If comprised in this way, it will become possible to obtain the 1st information and 2nd information which are required information by one demodulation. This eliminates the need to delete unnecessary information. Therefore, it becomes possible to prevent the decoding apparatus from becoming complicated.

  The receiving device of the present invention is a receiving device that receives a signal based on an encoded signal and has a demodulation function for demodulating the encoded signal, and the decoding unit that realizes the demodulation function includes: A decoding device is provided.

  According to the present invention, the number of bits of information input to the additional mapping unit that modulates the first information based on the second information is greater than the number of bits of information input to the mapping unit that modulates the first information. The configuration is reduced. Therefore, the state that the encoded signal output from the additional mapping unit can take can be made smaller than the state that the encoded signal output from the mapping unit can take. Therefore, it is possible to stably communicate the second information with high importance.

  First, the transmission device and the reception device in the embodiment of the present invention will be described. Thereafter, an encoding unit (encoding device) included in the transmission device and a decoding unit (decoding device) included in the reception device will be described. In the following, control information is taken as an example of information with high importance, data information is taken as an example of information with low importance, and the configuration and operation thereof will be described using these. The importance indicates the degree to which reliable transmission is required, and in the following embodiments, information having higher importance is set to have higher resistance to distortion during transmission. To do.

<Transmitter>
First, the configuration of a transmission apparatus according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a transmission apparatus according to an embodiment of the present invention.

  As shown in FIG. 1, the transmission apparatus 1 outputs the scrambler 2a that encrypts input data information by a predetermined method, the scrambler 2b that similarly encrypts control information, and the scrambler 2a. An FEC (Forward Error Correction) encoding unit 3a that provides redundancy for performing error correction on the receiving side, and an FEC encoding unit 3b that also provides redundancy to information output from the scrambler 2b , An interleaver 4a that rearranges information output from the FEC encoding unit 3a, an interleaver 4b that similarly rearranges information output from the FEC encoding unit 3b, and serial information output from the interleaver 4a. S / P converter 5 that rearranges the information in parallel, and the information output from interleaver 4b is multiplexed on a part of the plurality of information output in parallel from S / P converter 5. A plurality of encoded signals having different frequencies by modulation, and a plurality of encoded signals output from the encoding unit 6 are subjected to inverse fast Fourier transform (IFFT). An IFFT unit 7 that outputs as a baseband signal, a GI addition unit 8 that adds a guard interval (GI) to the baseband signal that is output from the IFFT unit 7, and a digital base that is output from the GI addition unit 8 From the D / A converter 9 that converts the band signal into analog, the transmitter 10 that converts the baseband signal output from the D / A converter 9 into a transmission signal, and performs processing such as amplification, and the transmitter 10 And an antenna 11 for transmitting an output transmission signal.

  The scramblers 2a and 2b respectively encrypt input data information and control information by a predetermined method. For example, when encryption is performed using a secret key method, a pseudo-random number may be generated, an exclusive-OR operation may be performed on the pseudo-random number and data information or control information, and the result may be output. Encryption is performed in this way to prevent information from being acquired by a third party during transmission.

  Data information and control information output from the scramblers 2a and 2b are input to the FEC encoding units 3a and 3b, respectively, and are made redundant. For example, block encoding for encoding a block (packet) of a predetermined size and convolutional encoding for encoding information of an arbitrary size are performed on the input information. As block coding, Reed-Solomon coding or Hamming coding can be used. Viterbi coding can be used as convolutional coding.

  Data information and control information output from the FEC encoding units 3a and 3b are input to the interleavers 4a and 4b, respectively, and the information is rearranged. Here, in particular, rearrangement is performed in bit units. As a result, even if an error occurs due to the influence of the transmission path, the error position can be dispersed, so that it is possible to perform effective error correction on the receiving side.

  Data information output from the interleaver 4 a is input to the S / P converter 5, converted from serial information to parallel information, and output to the encoder 6. In the encoding unit 6, in addition to the data information input from the S / P conversion unit 5, control information is input from the interleaver 4b. Then, the data information and the control information are modulated by the encoding unit 6 to generate a plurality of encoded signals. Details of the configuration and operation of the encoding unit 6 will be described later.

  When modulating by the OFDM system, the plurality of encoded signals generated by the encoding unit 6 are different in frequency and orthogonal to each other. The IFFT unit 7 performs IFFT on each encoded signal having these orthogonal frequencies, and outputs the result as one baseband signal.

  The baseband signal output from the IFFT unit 7 is input to the GI adding unit 8 and the GI is added. The GI is added every predetermined time interval (one symbol). In particular, a predetermined part at the rear of the symbol (for example, 1/8 or 1/16 of the symbol length) is copied and added to the head of the symbol. As a result, even if a so-called multipath is transmitted through a plurality of different paths and a signal shifted in time from each path is input to the receiving apparatus, the magnitude of the shift is GI. Interference between symbols can be prevented as long as it is smaller than.

  The baseband signal output from the GI adding unit 8 is input to the D / A conversion unit 9 and converted into an analog signal. Then, the baseband signal converted into the analog signal is input to the transmission unit 10. The transmitter 10 performs quadrature modulation for converting a baseband signal having an I component and a Q component into a frequency suitable for transmission, adjustment of signal strength, and the like, and a transmission signal is generated by performing these processes. Is done. The generated transmission signal is radiated into the air via the antenna 11.

<Receiving device>
Next, the configuration of the receiving apparatus according to the embodiment of the present invention will be described with reference to the drawings. FIG. 2 is a block diagram showing the configuration of the receiving apparatus according to the embodiment of the present invention.

  As illustrated in FIG. 2, the reception device 20 receives the transmission signal radiated from the transmission device 1, converts the transmission signal output from the antenna 21 into a baseband signal, and performs processing such as amplification. A receiver 22; an A / D converter 23 that converts an analog baseband signal output from the receiver 22 into digital; a GI remover 24 that removes a GI added to the baseband signal; and a GI remover An FFT unit 25 that outputs a baseband signal output from the unit 24 as a plurality of encoded signals having different frequencies by performing a fast Fourier transform (FFT), and a plurality of encoded signals output from the FFT unit 25 The decoding unit 26 that demodulates the signal and outputs a plurality of pieces of parallel information, and rearranges the plurality of pieces of parallel information output from the decoding unit 26 to obtain serial information. P / S conversion unit 27, deinterleaver 28a for rearranging serial information output from P / S conversion unit 27, and a part of the information output from decoding unit 26 are input and the information A deinterleaver 28b that performs rearrangement, an error correction unit 29a that performs error correction on information output from the deinterleaver 28a, an error correction unit 29b that similarly performs error correction on information output from the deinterleaver 28b, A descrambler 30a that decrypts encrypted information output from the error correction unit 29a by a predetermined method and outputs data information, and similarly decrypts information output from the error correction unit 29b and outputs control information. A descrambler 30b.

  The receiving unit 22 performs quadrature demodulation to obtain a baseband signal having an I component and a Q component by frequency-converting a transmission signal received via the antenna 21, and adjusts the signal strength. The analog baseband signal output from the receiving unit 22 is input to the A / D conversion unit 23 and converted into a digital signal.

  The digital baseband signal output from the A / D conversion unit 23 is input to the GI removal unit 24. The GI removal unit 24 removes the GI added to the baseband signal by the GI addition unit 8 of the transmission apparatus 1 illustrated in FIG.

  The baseband signal from which the GI has been removed by the GI removal unit 24 is converted into a frequency axis signal by the FFT unit 25. And it outputs as a some encoded signal which has a frequency which is mutually different and orthogonal.

  The decoding unit 26 demodulates a plurality of input encoded signals to obtain a plurality of information. The information obtained here includes data information and control information as described above. Therefore, the decoding unit 26 outputs the data information and the control information separately. Details of the configuration and operation of the decoding unit 26 will be described later.

  The data information output from the decoding unit 26 is input to the P / S conversion unit 27 and converted from parallel information to serial information. The serial data information to be output is input to the deinterleaver 28a. Here, rearrangement is performed in a manner opposite to that of the interleaver 4a in the transmission apparatus 1 of FIG. That is, the deinterleaver 28a performs rearrangement so that the information rearranged by the interleaver 4a is returned to the state before rearrangement. The same applies to the deinterleaver 28b, and the control information output from the decoding unit 26 is rearranged by a method that is just the reverse of the interleaver 4b.

  Data information and control information output from the deinterleavers 28a and 28b are input to error correction units 29a and 29b, respectively, and error correction is performed. At this time, decoding based on the redundancy added by the FEC encoders 3a and 3b in FIG. 1 is performed, thereby correcting the information error caused by the transmission.

  Data information and control information output from the error correction units 29a and 29b are input to the descramblers 30a and 30b, respectively, and decoded. At this time, the data information and control information encrypted in the scramblers 2a and 2b in FIG. 1 are decrypted. As a result, the data information and control information input to the transmission apparatus 1 in FIG. 1 are obtained via the reception apparatus 20.

  The transmission device 1 in FIG. 1 and the reception device 20 in FIG. 2 described above are merely examples, and the configuration may be changed as appropriate. For example, in the transmission apparatus 1, control information is input in series from the interleaver 4b to the encoding unit 6, but it may be input in parallel. In this case, an S / P conversion unit may be provided between the interleaver 4b and the encoding unit 6. Further, the same applies to the receiving device 20, and a P / S conversion unit may be provided between the decoding unit 26 and the deinterleaver 28b.

  In addition, although interleavers 4a and 4b perform bit interleaving in transmitting apparatus 1, instead of (or in addition to) this, encoding unit 6 may perform symbol interleaving that is rearranged for each symbol. Absent. Furthermore, any kind of replacement may be performed, such as time interleaving in which replacement is performed for each of a plurality of symbols, or frequency interleaving in which the frequency of modulation is switched. However, it is assumed that the receiving device 20 has a configuration capable of returning the replaced information to the state before the replacement.

  In addition, the transmission apparatus 1 may be configured to insert a pilot signal having a predetermined signal strength between the encoding unit 6 and the IFFT unit 7. And it is good also as providing the structure which performs the equalization process which correct | amends the distortion by a transmission line based on a pilot signal between the FFT part 25 and the decoding part 26 of the receiver 20.

<Encoding unit>
The encoding device (encoding unit) of the present invention receives first information (for example, data information) having a low importance level and second information (for example, control information) having a high importance level. The information is modulated and an encoded signal is output. In particular, the first information and the second information are input, and an additional mapping unit that modulates the first information based on the second information and outputs an encoded signal is provided. The additional mapping unit reflects the state of the bits of the input second information in the modulation of the first information. That is, even if the bit state of the first information input to the additional mapping unit is the same, the encoded signal to be output is different if the bit state of the second information is different.

  A specific example of the modulation method of the additional mapping unit will be described using each example of the encoding unit below. In particular, a direct method (first embodiment) in which the state of the second information bit is used in the modulation of the first information, and a signal modulated in accordance with the state of the second information bit is used in the modulation of the first information. The indirect method (second embodiment) will be described with one example each.

[First embodiment]
A first embodiment of the encoding unit 6 provided in the transmission apparatus 1 of FIG. 1 will be described with reference to the drawings. FIG. 3 is a block diagram showing a configuration of a first example of the encoding unit provided in the transmission apparatus according to the embodiment of the present invention. FIG. 4 is a constellation showing the modulation method of the encoding unit in the embodiment of the present invention. In the following description, the S / P conversion unit 5 shown in FIG. 1 outputs three pieces of information in parallel, and a case where one symbol is composed of 4 bits will be described as an example.

  As shown in FIG. 3, the encoding unit 6a of this example includes mapping units 61 and 62 that modulate information output from the S / P conversion unit 5 for each predetermined number of bits (symbols), and S / P conversion. And an additional mapping unit 63a that modulates the information output from the interleaver 4b in addition to the information output from the unit 5.

  The additional mapping unit 63a combines the information output from the information duplication unit 64 with the information duplication unit 64 that duplicates the information output from the interleaver 4b and the information output from the information duplication unit 64 into one symbol. An information insertion unit 65 to be formed and a mapping unit 66 that modulates information output from the information insertion unit 65 are provided.

  Next, the operation of the encoding unit 6a of this example will be described. As a specific example, a case where serial data information “1101010101” is input from the interleaver 4 a to the S / P converter 5 and control information “0” is output from the interleaver 4 b will be described.

  Further, the S / P converter 5 outputs the first, third, sixth and eighth bits “1011” of the input 10-bit serial data information to the mapping unit 61, and the second, fourth, seventh and ninth bits. Bit “1100” is input to the mapping unit 62, and the fifth and tenth bits “01” are input to the additional mapping unit 63a.

  The mapping units 61 and 62 modulate the 4-bit information output from the S / P conversion unit 5 as one symbol. For example, modulation is performed by a modulation method such as 16QAM, which is one of four-value information modulation methods. FIG. 4A shows a constellation when the mapping units 61 and 62 modulate with 16 QAM. If modulation is performed with 16QAM, one symbol position S corresponding to 4-bit information is selected from among the symbol positions S in which one quadrant has 4 points and 16 points in total.

  On the other hand, 2-bit information “01” is output from the S / P converter 5 to the additional mapping unit 63a. Also, 1-bit information “0” is output from the interleaver 4b. The 1-bit information “0” output from the interleaver 4 b is input to the information duplicating unit 64 and the same information “0” is added. Therefore, although it is substantially 1 bit (only 2 types can be taken), apparently 2-bit information “00” is obtained. This information “00” is input to the information insertion unit 65 and is combined with the information “01” output from the S / P conversion unit 5 here. For example, if the information output from the information duplication unit 64 is added before the information output from the S / P conversion unit 5, the information output from the information insertion unit 65 is “0001”.

  With the above operation, 4-bit information “0001” is output from the information insertion unit 65. However, in this example, since the information duplicating unit 64 duplicates the control information, the information output from the information inserting unit 65 is apparently 4 bits, but since it is substantially 3 bits, it can take a predetermined state. It will not be. Specifically, since “01” and “10” are not output from the information duplicating unit 64, “01XX” and “10XX” are not output from the information inserting unit 65, and these states are not obtained. (X is an arbitrary number of 0 or 1).

  The mapping unit 66 to which 4-bit information is input from the information insertion unit 65 performs modulation with 16QAM, for example, similar to the mapping units 61 and 62. The constellation in this case is shown in FIG. As shown in FIG. 4 (b), the quadrant to which the symbol position S in FIG. 4 (b) belongs is determined based on apparently 2 bits (substantially 1 bit) of control information that is important information. Based on the data information, the symbol position S of the four points in the quadrant determined based on the control information is determined.

  Assuming that the mapping unit 66 modulates in this way, the control information is substantially 1 bit, so the number of possible quadrants is limited to two. In the example shown in FIG. 4B, the modulated signal is not arranged in the second quadrant where the I component is negative and the Q component is positive, and in the fourth quadrant where the I component is positive and the Q component is negative. It will be.

  If the encoding unit 6a is configured as described above and control information that is important information is transmitted, the control information can be satisfactorily communicated even if the transmission path is poor. In particular, as shown in FIG. 4B, since a range (second quadrant and fourth quadrant) that cannot be taken by the symbol position S is set, the transmission path is poor and the symbol position S is in these quadrants on the receiving side. When it is recognized, the correct symbol position S can be obtained again or confirmed as an error. Therefore, it is possible to suppress erroneous recognition of control information on the receiving side.

  Furthermore, in this example, the modulation methods performed by the mapping units 61, 62, and 66 can all be the same modulation method. For this reason, it is possible to prevent the configuration of the encoding unit 6a and, consequently, the configuration of the transmission device 1 from becoming complicated.

  In the above-described example, the control information is duplicated, but a configuration in which a predetermined bit of “0” or “1” is added may be used. Even in such a configuration, the same effect can be obtained because the apparent number of bits can be increased without increasing the number of substantial bits. However, as in the example shown in FIG. 4B, if the configuration is such that symbols can be placed in quadrants that are symmetrical with respect to the origin by modulation, each quadrant adjacent to the placeable quadrant can be made unplaceable. It becomes. Therefore, it is possible to effectively suppress the occurrence of misidentification due to a phase shift and entering an adjacent quadrant.

  Further, the mapping unit 66 may perform modulation as shown in FIG. FIG. 5 is a constellation showing another example of the modulation method of the encoding unit in the embodiment of the present invention. The modulation method shown in FIG. 5A is almost the same as the modulation method shown in FIG. 4B, but the arrangement is changed. In particular, the four symbol positions S arranged in the first quadrant and the third quadrant in FIG. 4B are arranged so that the centers of the four points are on the I axis.

  That is, the symbol positions S are arranged in a lattice shape (square) that is symmetrical about the Q axis with the center on the I axis. In addition, each line formed by connecting adjacent points of each lattice is perpendicular or parallel to the Q axis. On the other hand, in the arrangement shown in FIG. 4B, all lines formed by connecting adjacent points of the lattice form an angle of 45 ° with the symmetry axis.

  If modulation is performed in this way, errors can be suppressed more than the modulation method shown in FIG. This will be described with reference to FIG. FIG. 5B is a constellation shown for the modulation method similar to FIG. 4B, and is shown for comparison with the modulation method shown in FIG. Also, the broken line P in FIG. 5 indicates the average power at the four symbol positions S in a lattice pattern. FIGS. 5A and 5B show a case where the average power P is equal. Further, the distance between adjacent symbol positions S is t, and the radius of the average power P is u.

In the modulation method shown in FIG. 5B, the distance between the symbol position S closest to the origin and the origin is u− (2 ^1/2 / 2) × t. On the other hand, in the modulation method shown in FIG. 5A, the distance between the symbol position S closest to the origin and the origin is the length of the hypotenuse of a right triangle having two sides of ut / 2 and t / 2. The hypotenuse is longer than u-t / 2, the u-t / 2> u- ( 2 1/2 / 2) × t. Therefore, the power at the symbol position S closest to the origin in FIG. 5A is larger than that in FIG. Therefore, the modulation method shown in FIG. 5 (a) can increase the power of the encoded signal that minimizes the power, so that errors can be further suppressed.

  When the symbol position S is not arranged at the center of the lattice, the arrangement method shown in FIG. 5A can maximize the distance between the symbol position S closest to the origin and the origin. Further, the symbol position S in FIG. 5A is symmetric with respect to the Q axis, but may not be symmetric with respect to the Q axis. For example, the I axis may be the symmetry axis. However, if the Q axis is symmetric, the control information can be demodulated based on the sign of the real component as in the case of modulation with BPSK. Therefore, it is preferable because the demodulation process on the receiving side can be prevented from becoming complicated.

[Second Embodiment]
A second embodiment of the encoding unit 6 provided in the transmission apparatus 1 of FIG. 1 will be described with reference to the drawings. FIG. 6 is a block diagram illustrating a configuration of a second example of the encoding unit provided in the transmission apparatus according to the embodiment of the present invention, and corresponds to FIG. 3 illustrating the first example. In addition, the same code | symbol is attached | subjected about the part similar to FIG. 3, and the detailed description is abbreviate | omitted. The information shown as a specific example is the same as that shown in FIG.

  This example is different from the first example only in the configuration of the additional mapping unit 63b, and the other configurations are the same. Therefore, the additional mapping unit 63b will be mainly described. The additional mapping unit 63b modulates the information input from the S / P converter 5 based on the first modulation unit 67 that modulates the information input from the interleaver 4b and the signal input from the first modulation unit 67. A second modulation unit 68.

  The first modulation unit 67 modulates the 1-bit control information “0” input from the interleaver 4b by a modulation method for 1-bit information such as BPSK, for example. The signal output from the first modulation unit 47 is input to the second modulation unit 68. Then, the second modulation unit 68 modulates the 2-bit information “01” input from the S / P conversion unit 5 based on the signal output from the first modulation unit 67.

  The signal output from the second modulator 68 can be the same as that in the first embodiment. That is, the signal point arrangement as shown in FIGS. 5A and 5B can be obtained. Therefore, it is possible to obtain the same effect as in the first embodiment. That is, by creating a range in which the symbol position S cannot be taken, it is possible to suppress erroneous recognition of control information on the receiving side.

  In addition, such a configuration eliminates the need for a device that duplicates or inserts bits of control information. For this reason, it is possible to prevent the configuration of the encoding unit 6b and, consequently, the configuration of the transmission device 1 from becoming complicated.

  In addition, about the encoding parts 6a and 6b of 1st and 2nd Example, the information (number of the encoding signals multiplexed) output in parallel from the S / P conversion part 5 is three, and this The configuration in which the control information is inserted into one of them has been described as an example, but the present invention is not limited to this example. Any configuration may be used as long as there are n pieces of information output in parallel and control information is inserted into m pieces of information (where n and m are natural numbers, and n> m).

  In the encoding units 6a and 6b of the first and second embodiments, information input to the mapping units 61 and 62 is 4 bits, and information input to the additional mapping units 63a and 63b is 3 bits. Although the configuration has been described as an example, the present invention is not limited to this example. That is, if the information input to the mapping units 61 and 62 is p bits and the information input to the additional mapping units 63a and 63b is less than p bits, the control information can be transmitted satisfactorily. An effect can be obtained.

  Further, in the additional mapping unit 63a provided in the encoding unit 6a of the first embodiment, any configuration is possible as long as the data information is q bits, the control information is r bits, and the added data is pqr bits. (However, p, q, and r are natural numbers and satisfy p-q-r> 0).

  In addition, the phase difference of the encoded signal (symbol position S on the constellation) caused by the difference of relatively important information (control information) is the symbol position S caused by the difference of relatively unimportant information (data information). It is preferable that the phase difference be larger than the above. For example, a phase difference of π / 2 or more may be caused by a difference in information that is relatively important. In addition, in the additional mapping unit 63a provided in the encoding unit 6a of the first embodiment, when information that is relatively important information is most reliably transmitted, it is preferable to set r = 1 as in the example shown in FIG. .

  As for the modulation method, QPSK, 16QAM (including the case where the interval between adjacent symbol positions across the axis is not equal to the interval between adjacent symbol positions in the same quadrant, including the so-called non-uniform case), 64QAM ( Any method such as non-uniform) may be used.

<Decryption unit>
The decoding device (decoding unit) of the present invention demodulates an input encoded signal, and first information (for example, data information) having low importance and second information (for example, control) having high importance. Information). In particular, a separation demapping unit that outputs the first information and the second information based on the input encoded signal is provided. The encoded signal input to the separation demapping unit is an encoded signal output from the additional mapping unit described above. That is, it is a signal created by reflecting the state of the bits of the second information when the first information is modulated.

  A specific example of the demodulation method of the separation demapping unit will be described using each example of the decoding unit below. In particular, the information (or signal) obtained by demodulating the encoded signal is further processed to obtain the first information and the second information (first embodiment), and the encoded signal is demodulated to the first information. A direct method (second embodiment) for obtaining one information and second information will be described by giving one example each.

[First embodiment]
The decoding unit 26 provided in the receiving device 20 of FIG. 2 will be described with reference to the drawings. FIG. 7 is a block diagram showing a configuration of a decoding unit provided in the receiving apparatus according to the embodiment of the present invention. Similar to the description in the encoding unit 6 described above, an example will be described in which three encoded signals are multiplexed and transmitted, and one symbol is composed of 4 bits. In this example, it is assumed that an encoded signal modulated by the modulation method shown in FIGS. 4A and 4B is input.

  As shown in FIG. 7, the decoding unit 26 a of this example demodulates each encoded signal output from the FFT unit 25 to obtain information on a predetermined number of bits (symbols) and obtains information on a P / S conversion unit 27. Demapping units 261 and 262 that output to the signal, and a demultiplexing unit 263a that demodulates the encoded signal output from the FFT unit 25 and separates and outputs the information to the P / S conversion unit 27 and the deinterleaver 28b. .

  The demultiplexing unit 263a separates the control information and the data information from the first demapping unit 264 that demodulates the encoded signal output from the FFT unit 25, and the information output from the first demapping unit 264, and outputs the separated information. And an information deletion unit 266 that deletes part of the control information output from the information extraction unit 265.

  Next, the operation of the decoding unit 26a of this example will be described. As a specific example, a case will be described in which an encoded signal obtained by modulating the information used in the description of the encoding units 6a and 6b described above is input to the decoding unit 26a of the present example.

  The demapping units 261 and 262 demodulate the encoded signal output from the FFT unit 25. At this time, the demapping units 261 and 262 perform demodulation by a method according to the modulation method performed by the mapping units 61 and 62 of the encoding units 6a and 6b described above. That is, when the mapping units 61 and 62 perform modulation with 16QAM as described above, the demapping units 261 and 262 correspond to any symbol position S shown in FIG. Demodulate by deciding whether to do. Then, the bit corresponding to the obtained symbol position S is output to the P / S converter 27.

  On the other hand, the first demapping unit 264 of the separation demapping unit 263a also performs demodulation similar to the demapping units 261 and 262 described above. However, the information obtained from the first demapping unit 264 includes control information “00” and data information “01”. Information output from the first demapping unit 264 is input to the information extraction unit 265 and separated into data information and control information. Then, the control information “00” is output to the information deletion unit 266 and the data information “01” is output to the P / S conversion unit 27.

  In the P / S conversion unit 27, the data information “1011” and “1100” output from the demapping units 261 and 262 and the data information “01” output from the information extraction unit 265 are combined, Data information “1101010101” is obtained. The method for performing the combination is the reverse of the method for the S / P converter 5 of the transmission apparatus 1.

  Further, the information deleting unit 266 deletes one unnecessary bit from the input control information. As described above, the encoded signal is a signal that is apparently modulated by a 4-bit modulation method, but is substantially obtained by modulating 3-bit information. Therefore, one of the bits obtained by demodulation is deleted. Then, the control information “0” output from the information deletion unit 266 is input to the deinterleaver 28b.

  If the decoding unit 26a is configured as described above and receives control information that is important information, the control information can be satisfactorily communicated even if the transmission path is poor. In particular, as shown in FIG. 4B, since there are ranges (second quadrant and fourth quadrant) that the symbol position S cannot take, the transmission path is inferior and the symbol position S is within these ranges. In such a case, it is possible to re-determine the correct symbol position S or confirm that it is an error by the first demapping unit 264 or subsequent processing. For this reason, it is possible to suppress erroneous recognition of the control information.

  Further, in this example, since the input encoded signals are all modulated by the same modulation method, the demodulation methods performed by the demapping units 261 and 262 and the first demapping unit 264 can all be the same demodulation method. . For this reason, it is possible to prevent the configuration of the decoding unit 26a, and hence the configuration of the receiving device 20, from becoming complicated.

  In the above-described example, one symbol is 4 bits, and the demapping units 261 and 262 and the first demapping unit 264 perform the demodulation corresponding to 16QAM as an example, but the above-described encoding unit 6a is described. , 6b, the present invention is not limited to this example.

[Second Embodiment]
A description will be given of a second embodiment of the decoding unit 26 provided in the reception device 20 of FIG. 2 with reference to the drawings. FIG. 8 is a block diagram showing a configuration of a second example of the decoding unit provided in the receiving apparatus according to the embodiment of the present invention, and corresponds to FIG. 7 showing the first example. In addition, the same code | symbol is attached | subjected about the part similar to FIG. 7, and the detailed description is abbreviate | omitted. The information shown as a specific example is the same as that shown in FIG.

  Further, the decoding unit 26b of this example includes an encoded signal modulated by the modulation method shown in FIG. 4A, an encoded signal modulated by the modulation method shown in FIG. Shall be entered. In particular, the demapping units 261 and 262 are the same as those in the first embodiment, and an encoded signal modulated by the modulation method shown in FIG. On the other hand, an encoded signal modulated by the modulation method shown in FIG. 5A is input to the second demapping unit 267 described later.

  This example is different from the first example only in the configuration of the separation demapping unit 263b, and the other configurations are the same. Therefore, the separation demapping unit 263b will be mainly described. The separation demapping unit 263b separates the control information and the data information from the second demapping unit 267 that demodulates the encoded signal input from the FFT unit 25, and the information output from the second demapping unit 267, and outputs them. And an information extraction unit 268 that performs the above-described operation.

  The second demapping unit 267 receives an encoded signal modulated by the modulation method illustrated in FIG. Unlike the first demapping unit 264 of the first embodiment, the second demapping unit 267 outputs 3-bit information “001” when demodulating. Then, the information extraction unit 268 extracts the control information “0” from the input information “001” and outputs it to the deinterleaver 28b. Further, the data information “01” is output to the P / S converter 27.

  With this configuration, the second demapping unit 267 can directly obtain control information and data information without performing processing for deleting the extracted control information. Therefore, it is possible to prevent the configuration of the decoding unit 26b and, consequently, the configuration of the receiving device 20 from becoming complicated.

  Although the case where the encoded signal modulated by the modulation method shown in FIG. 5A is demodulated has been shown, the present invention is also applicable to the case where the encoded signal modulated by the modulation method shown in FIG. 5B is demodulated. An example configuration can be used. In this case, it is determined whether the symbol position S is within the first quadrant or the third quadrant, thereby determining a 1-bit value as control information.

  In the decoding units 26a and 26b of the first and second embodiments, the number of encoded signals to be multiplexed is three, and control information is inserted into one of them. Similarly to the encoding units 6a and 6b described above, the present invention is not limited to this example.

<Modification>
The transmission device 1 and the reception device 20 described above may be a single device. That is, a communication device that can perform transmission and reception may be used. In that case, the antennas 11 and 21 may be shared.

  Further, although control information is given as an example of relatively important information and data information is given as an example of relatively unimportant information, the present invention is not limited to this. For example, pilot information that is a known value may be transmitted instead of the control information. With this configuration, it is possible to accurately correct distortion on the receiving side even in a situation where transmission signals are easily distorted and fading is likely to occur, such as in mobile communication.

  Further, in the transmission device 1 and the reception device 20 described above, the processing performed by the encoding unit 6 and the decoding unit 26 may be performed by a control device such as a microcomputer. Further, all or part of the functions realized by such a control device is described as a program, and the program is executed on a program execution device (for example, a computer) to realize all or part of the functions. It doesn't matter if you do.

  In addition to the above-described case, the transmission device 1 and the reception device 20 can be realized by hardware or a combination of hardware and software. Further, when the transmission device 1 and the reception device 20 are configured using software, a block diagram of a part realized by software represents a functional block diagram of the part.

  As mentioned above, although each embodiment in the present invention was described, the range of the present invention is not limited to this, and can be carried out by adding various changes without departing from the gist of the invention.

  The present invention relates to an encoding device that encodes information to obtain a transmission signal and a transmission device including the same. Further, the present invention relates to a decoding device that obtains information by decoding a transmission signal and a receiving device including the same. In particular, the present invention is preferably applied to an encoding device and a decoding device that encode and decode relatively important information and relatively unimportant information.

These are block diagrams which show the structure of the transmitter in embodiment of this invention. These are block diagrams which show the structure of the receiver in embodiment of this invention. These are block diagrams which show the structure of the 1st Example of the encoding part with which the transmitter in embodiment of this invention is provided. These are the constellations shown about the modulation method of the encoding part in embodiment of this invention. These are the constellations shown about another example of the modulation method of the encoding part in embodiment of this invention. These are block diagrams which show the structure of the 2nd Example of the encoding part with which the transmitter in embodiment of this invention is provided. These are block diagrams which show the structure of the decoding part with which the receiver in embodiment of this invention is provided. These are block diagrams which show the structure of 2nd Example of the decoding part with which the receiver in embodiment of this invention is provided. These are block diagrams which show the structure of the conventional encoding apparatus. These are the constellations shown about the modulation method of the conventional encoding apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Transmitter 2a, 2b Scrambler 3a, 3b FEC encoding part 4a, 4b Interleaver 5 S / P conversion part 6 Encoding part 61, 62, 66 Mapping part 63a, 63b Additional mapping part 64 Information duplication part 65 Information insertion part 67 1st modulation unit 68 2nd modulation unit 7 IFFT unit 8 GI addition unit 9 D / A conversion unit 10 transmission unit 11 antenna 20 reception device 21 antenna 22 reception unit 23 A / D conversion unit 24 GI removal unit 25 FFT unit 26 Decoding unit 261, 262 Demapping unit 263a, 263b Separation demapping unit 264 First demapping unit 265, 268 Information extraction unit 266 Information deletion unit 267 Second demapping unit 27 P / S conversion unit 28a, 28b Deinterleaver 29a 29b Error correction unit 30a, 30b Descrambler

Claims (11)

An encoding device that modulates input information and outputs an encoded signal,
A mapping unit that modulates input p-bit first information and outputs one encoded signal;
q-bit first information and r-bit second information having higher importance than the first information are input, and the first information is modulated based on the second information, An additional mapping unit for outputting an encoded signal;
Each with at least one
An encoding apparatus characterized in that a sum of q and r is made smaller than p.   The code according to claim 1, wherein the additional mapping unit makes the phase difference of the encoded signal caused by the difference of the second information larger than the phase difference caused by the difference of the first information. Device. The additional mapping unit is
An information insertion unit that adds pq-r bits of third information to the first information and the second information, and combines the first information, the second information, and the third information into p-bit information; In addition to preparing
The encoding apparatus according to claim 1 or 2, wherein the additional mapping unit modulates p-bit information output from the information insertion unit to obtain an encoded signal.   The encoding apparatus according to claim 3, wherein the additional mapping unit further includes an information duplicating unit that duplicates the second information to obtain the third information. The additional mapping unit is
A first modulator for modulating the second information;
A second modulation unit that modulates the first information based on a signal output from the first modulation unit and outputs an encoded signal;
The encoding apparatus according to claim 1, further comprising: When the modulation method by the additional mapping unit is represented on the constellation,
Two lattice point groups arranged in a lattice pattern with the same distance between adjacent points are arranged so that a predetermined straight line passing through the origin is a symmetric axis, and on a straight line perpendicular to the symmetric axis and passing through the origin. Each center of the lattice point group is located,
6. The encoding apparatus according to claim 1, wherein all lines formed by connecting adjacent points in the lattice point group are perpendicular to or parallel to the axis of symmetry. A transmission device having a modulation function for modulating input information and transmitting a signal based on an encoded signal obtained by the modulation function,
A transmission device comprising the encoding device according to any one of claims 1 to 6 as an encoding unit that realizes the modulation function. A decoding device that demodulates an input encoded signal and outputs information,
A demapping unit that outputs p-bit first information based on one input encoded signal;
A separate demapping unit that outputs the q-bit first information and the r-bit second information having higher importance than the first information, based on one encoded signal input;
Each with at least one
A decoding apparatus characterized in that a sum of q and r is made smaller than p. The separation demapping unit includes:
Based on the input encoded signal, the first information of q bits, the second information of r bits, and the third information of pqr bits are output. 1 demapping part,
Among the information output from the first demapping unit, an information extracting unit that outputs the first information, the second information, and the third information separately;
An information deletion unit that deletes the third information and outputs the second information from the second information and the third information output from the information extraction unit;
The decoding device according to claim 8, further comprising: The separation demapping unit includes:
A second demapping unit that outputs information in which the q-bit first information and the r-bit second information are combined based on an input encoded signal;
Among the information output from the second demapping unit, an information extraction unit that outputs the first information and the second information separately;
The decoding device according to claim 8, further comprising: A receiving device that receives a signal based on an encoded signal and has a demodulation function for demodulating the encoded signal,
A receiving device comprising the decoding device according to any one of claims 8 to 10 as a decoding unit that realizes the demodulation function.

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