JP2018078553A - Transmission device, reception device, and chip - Google Patents

Abstract

PROBLEM TO BE SOLVED: To estimate a transmission path characteristic with improved precision without increasing SP signals in a MIMO transmission system or MISO transmission system.SOLUTION: In a transmission device including a plurality of transmission systems, an OFDM frame construction unit of at least one transmission system alternately multiplies an SP signal by a first coefficient and a second coefficient in a symbol (time) direction and a carrier (frequency) direction, and alternately multiplies a CP signal by the first coefficient and the second coefficient every number corresponding to a symbol (time) interval of the SP signal. In addition, a reception device or chip combines the SP signal and the CP signal and estimates transmission path characteristics from the transmission systems.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a transmission device, a reception device, and a chip, and more particularly to a transmission device, a reception device, and a chip that transmit and receive a signal including a pilot signal (pilot carrier).

  In the ISDB-T (Integrated Services Digital Broadcasting-Terrestrial) system, which is the current terrestrial digital broadcasting system in Japan, OFDM (Orthogonal Frequency Division Multiplexing) is used as a modulation system, and a predetermined frequency of an OFDM frame is used. A pilot signal is assigned to a carrier symbol, and the reception side is configured to calculate transmission path characteristics (transmission path response) from the reception state of the pilot signal and to receive data accurately (Non-patent Document 1). .

  On the other hand, in the next-generation digital terrestrial broadcasting system (hereinafter also referred to as next-generation terrestrial transmission system) that assumes Super Hi-Vision broadcasting using terrestrial waves, various modulation systems and new transmission systems are used to expand the transmission capacity. In particular, MIMO (Multi-Input Multi-Output) transmission method that uses multiple antennas on both the transmitting side and the receiving side, and multiple antennas on the transmitting side and one antenna on the receiving side The MISO (Multi-Input Single-Output) transmission method that uses the WDM has been energetically studied.

  In the MIMO transmission system and the MISO transmission system, it is necessary to estimate transmission path characteristics from each transmission antenna to the reception antenna individually as accurately as possible. Thus, using orthogonalized pilot signals, the pilot signals are made different for each OFDM signal transmitted from each transmitting antenna, and the characteristics of each transmission path are calculated from the received signals. Hereinafter, the principle will be briefly described by taking a 2 × 2 MIMO transmission system with two transmitting antennas and two receiving antennas as an example.

  A known SP (Scattered Pilot) signal is used to individually estimate the transmission path characteristics of the signal arriving from each transmission antenna. The transmitting antennas are Tx1 and Tx2, and the receiving antennas are Rx1 and Rx2. In order to make the two series of SP signals transmitted from Tx1 and Tx2 different, a part of the SP signals transmitted from Tx2 is subjected to sign inversion, and an SP signal orthogonal to the Tx1 SP signal is transmitted.

  FIG. 5 shows a conventional arrangement of pilot signals in each OFDM signal transmitted from two systems Tx1 and Tx2. The arrangement of SP signals on the Tx1 side shown in FIG. 5A is the same as that of ISDB-T. SP signals are arranged every 12 carriers in the carrier (frequency) direction and every 4 symbols in the symbol (time) direction. Has been. In the figure, white squares indicate data symbols, and hatched squares in the diagonal direction indicate normal (coefficient +1) SP signals. A continuous CP (Continual Pilot) signal is arranged on the carrier at the end of the OFDM frame.

  FIG. 5B shows the arrangement of pilot signals on the Tx2 side. The positions of the SP signal and CP signal are the same as Tx1, but every other SP signal is inverted in sign. In FIG. 5B, diagonal hatched squares indicate normal (coefficient +1) SP signals, and cross-hatched squares indicate SP signals that have been sign-inverted (multiplied by coefficient -1). A continuous CP signal identical to Tx1 is arranged on the carrier at the end of the OFDM frame.

  Since the reception antennas Rx1 and Rx2 receive the signals transmitted from the transmission antennas Tx1 and Tx2, the SP signals are also received by mixing the Tx1 and Tx2 SP signals. Therefore, the transmission path characteristics from Tx1 and the transmission path characteristics from Tx2 are individually estimated by combining the SP signal and the adjacent SP signal. Here, the transmission path characteristics are estimated by combining SP signals adjacent in the frequency direction. Note that the calculation can be similarly performed by combining SP signals adjacent in the time direction or combining SP signals adjacent in the oblique direction.

  Since SP signals adjacent in the frequency direction are separated by 12 carriers in the frequency (carrier) direction in the same symbol row, the SP signals on the Tx1 side are P1 (l, k) and P1 (l, k + 12). Assuming that the SP signal on the Tx2 side is P2 (l, k) and P2 (l, k + 12), only P2 (l, k + 12) is sign-inverted, so that equation (1) holds. Here, l is a symbol number and k is a carrier number.

  When the transmission path characteristic (transmission path response) from the transmission antenna Tx1 to the reception antenna Rx1 is h11 and the transmission path characteristic (transmission path response) from the transmission antenna Tx2 to the reception antenna Rx1 is h12, the received signal R1 (l, k) and R1 (l, k + 12) are given by the following equation (2).

  Here, assuming that the frequency interval between the carrier k and the carrier (k + 12) is narrow and the transmission path characteristics are equal, h11 (l, k) = h11 (l, k + 12), h12 (l, k) = h12 Since (l, k + 12) holds, the following equation (3) is derived from this assumption and equations (1) and (2).

  By solving the equation (3), the transmission path characteristic for the receiving antenna Rx1 is obtained by the following equation (4).

  The transmission path characteristics from the transmission antennas Tx1 and Tx2 to the reception antenna Rx2 can be similarly obtained. (Non-patent document 2, Patent document 1)

Japanese Patent No. 5291484

“Transmission system for digital terrestrial television broadcasting” standard, ARIB STD-B31, Japan Radio Industry Association Zenichi Narusei et al., “MIMO-OFDM transmission technology for mobile reception using space-time coding”, NHK R & D, Japan Broadcasting Corporation, Broadcasting Technology Laboratory, November 2012, No. 136, pp. 41-49

  Thus, until now, the characteristics of each transmission path have been estimated using the SP signal, but in the next-generation terrestrial transmission system, it is assumed that a modulation system with a large number of modulation multi-values is adopted, In order to accurately perform demapping of received signals, it is required to estimate transmission path characteristics more accurately.

  In order to accurately estimate the transmission path characteristics, it is preferable to increase the SP signal. However, if the SP signal is increased in a certain frame configuration, the data carrier is decreased. Therefore, the SP signal is increased. This is undesirable from the viewpoint of increasing the transmission capacity.

  Accordingly, an object of the present invention made in view of the above-described problems is to provide a transmission apparatus capable of estimating transmission path characteristics more accurately without increasing the SP signal in the MIMO transmission system or the MISO transmission system. It is to provide a receiving device and a chip.

  In order to solve the above-described problems, a transmission apparatus according to the present invention includes a plurality of transmission systems, and is distributed in a predetermined symbol (time) interval and carrier (frequency) interval in a transmission apparatus that transmits OFDM signals. First and second OFDM frame configuration units that form an OFDM frame including a CP signal continuously arranged on a predetermined frequency carrier, and at least one of the OFDM frame configuration units, The signal is alternately multiplied by the first coefficient and the second coefficient in the symbol (time) direction and the carrier (frequency) direction, and corresponds to the predetermined symbol (time) interval for the CP signal. An OFDM frame in which the first coefficient and the second coefficient are alternately multiplied for each number to be configured is configured.

  In addition, the transmission apparatus may be configured such that the OFDM frame configured by the at least one OFDM frame configuration unit has a relationship (periodicity) between the first coefficient and the second coefficient in the SP signal even in the CP signal. It is desirable that it be maintained.

  In the transmission apparatus, it is preferable that the first coefficient and the second coefficient are +1 and −1, and multiplication is performed in one OFDM frame configuration unit and multiplication is not performed in the other OFDM frame configuration unit.

  In the transmission apparatus, the first coefficient and the second coefficient are +1 and 0, and the coefficients multiplied by the SP signal or CP signal at the corresponding positions are opposite in the first and second OFDM frame configuration units. It is desirable that

  In order to solve the above-described problems, a chip according to the present invention is mounted on a transmission apparatus and is continuously distributed to a predetermined frequency carrier and SP signals distributed in predetermined symbol (time) intervals and carrier (frequency) intervals. Is a chip that generates an OFDM frame including a CP signal that is arranged in a random manner, and is an SP in which at least a first coefficient and a second coefficient are alternately multiplied in a symbol (time) direction and a carrier (frequency) direction An OFDM frame including a CP signal obtained by alternately multiplying the first coefficient and the second coefficient for each signal and the number corresponding to the symbol (time) interval of the SP signal is created.

  In order to solve the above problems, a receiving apparatus according to the present invention receives an OFDM signal transmitted from a plurality of transmission systems, and the OFDM signal transmitted from at least one transmission system has a symbol (time) direction. For each SP signal obtained by alternately multiplying the first coefficient and the second coefficient in the carrier (frequency) direction and the number corresponding to the symbol (time) interval of the SP signal, the first coefficient and the second coefficient It includes a CP signal that is alternately multiplied by a coefficient, and the transmission signal characteristics from the plurality of transmission systems are estimated by combining the SP signal and the CP signal.

  In addition, the OFDM frame received from the at least one transmission system and received by the receiving apparatus has a relationship (periodicity) between the first coefficient and the second coefficient in the SP signal, even in the CP signal. It is desirable that it be maintained.

  Further, it is desirable that the receiving apparatus uniformly processes the process of estimating the transmission path characteristics by regarding the CP signal as an SP signal.

  In order to solve the above-described problem, a chip according to the present invention is a chip mounted on a receiving device, and at least a first coefficient and a second coefficient are alternately arranged in a symbol (time) direction and a carrier (frequency) direction. And an OFDM signal including a CP signal that is alternately multiplied by a first coefficient and a second coefficient for each SP signal multiplied by the number corresponding to the symbol (time) interval of the SP signal, The transmission path characteristics from a plurality of transmission systems are estimated by combining the SP signal and the CP signal.

  According to the transmission apparatus, the reception apparatus, and the chip of the present invention, it is possible to more accurately estimate the transmission path characteristics without increasing the SP signal in the MIMO transmission system or the MISO transmission system.

  Also, according to the receiving apparatus and chip of the present invention, the CP signal can be regarded as an SP signal and processed uniformly, so that the signal processing can be made more efficient.

It is a block diagram which shows an example of the transmitter of this invention. It is a figure which shows the example of the pilot (SP, CP) signal in the sign inversion system of this invention. It is a figure which shows the example of the pilot (SP, CP) signal in the null system of this invention. It is a block diagram which shows an example of the receiver of this invention. It is a figure which shows the example of the pilot (SP, CP) signal in the conventional code inversion system.

  Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1)
A transmission apparatus as Embodiment 1 of the present invention will be described. FIG. 1 is a block diagram illustrating an example of a transmission apparatus. The transmission apparatus 10 is a so-called OFDM transmission apparatus, and includes an error correction encoding unit 11, a mapping unit 12, a space-time encoding unit 13, OFDM frame configuration units 14 and 15, a pilot signal generation unit 16, an IFFT (Inverse Fast Fourier). Transform) portions 17 and 18 and transmission antennas Tx1 and Tx2. The transmission apparatus 10 of the present invention performs a MIMO transmission system or a MISO transmission system, and the OFDM frame configuration units 14 and 15, IFFT units 17 and 18, and transmission antennas Tx1 and Tx2 correspond to at least the transmission system. Two systems are provided.

  The error correction encoding unit 11 receives data (for example, a TS (transport stream) of a video signal) transmitted from the transmission apparatus 10, performs error correction encoding processing, and maps the encoded data to the mapping unit 12. Output to. As the error correction code, an RS code, a convolutional code, a turbo code, an LDPC (Low Density Parity Check) code, or the like is used. When performing error correction coding processing, processing such as energy spreading and interleaving may be performed as necessary.

  The mapping unit 12 receives the data corrected by the error correction encoding unit 11 and performs mapping on the IQ plane by a predetermined modulation method to perform data carrier modulation. The mapped data is output to the space-time encoding unit 13. As a modulation method, in addition to QPSK (Quadrature Phase Shift Keying), 16QAM (Quadrature Amplitude Modulation), and 64 QAM used in ISDB-T, 256QAM, 1024QAM, 4096QAM, and the like may be used in the next generation terrestrial transmission method. .

  The space-time encoding unit 13 receives the data mapped by the mapping unit 12, performs space-time encoding processing, divides the space-time encoded data into two systems, and OFDM frame configuration unit 14 of each transmission system , 15. As the space-time coding process, for example, space-time block coding (STBC) or space frequency block coding (SFBC) is used.

  The OFDM frame configuration units (first and second OFDM frame configuration units) 14 and 15 receive the data space-time encoded by the space-time encoding unit 13 as input, and pilot signals (pilot carriers) and TMCC ( An OFDM transmission frame is configured by adding Transmission and Multiplexing Configuration Control (control information carrier) and the like. The OFDM frame configuration units 14 and 15 are provided for each transmission system, and output the generated OFDM frame signals to the IFFT units 17 and 18 of the respective systems. A pilot signal (SP signal, CP signal) is input from the pilot signal generation unit 16, and TMCC is generated and input based on various transmission parameters by a TMCC generation unit (not shown). Each OFDM frame generated by the OFDM frame configuration units 14 and 15 will be described later. The process of multiplying a pilot signal, which will be described later, by a predetermined coefficient may be performed by the OFDM frame configuration units 14 and 15, or may be performed by the pilot signal generation unit 16.

  The pilot signal generation unit 16 generates a pilot signal (SP signal, CP signal) and outputs it to the OFDM frame configuration units 14 and 15. The pilot signal is, for example, BPSK (Binary Phase Shift Keying) related to Wi corresponding to the carrier number i of the OFDM segment with respect to the output Wi of the PRBS (Pseudo-random bit sequence) generation circuit. ) Generate as a signal. The process of multiplying the pilot signal described later by the coefficient may be performed by the pilot signal generation unit 16, and the SP signal and CP signal multiplied by the coefficient are sent to the OFDM frame configuration unit 14 and the OFDM frame configuration unit 15. You may supply. It is technically equivalent whether the OFDM frame configuration units 14 and 15 and the pilot signal generation unit 16 perform multiplication.

  The IFFT units 17 and 18 receive the OFDM frame signals output from the OFDM frame configuration units 14 and 15 and perform inverse fast Fourier transform on the frequency domain OFDM signals to generate time domain OFDM signals. Thereafter, although not shown in the figure, a process such as adding a GI (guard interval) and converting the baseband frequency to a predetermined frequency band RF (Radio Frequency) is performed, and each OFDM signal is transmitted for each transmission system. It is transmitted as a broadcast wave via the antennas Tx1 and Tx2.

  Each OFDM frame generated by the OFDM frame configuration units 14 and 15 will be described with reference to the drawings. FIG. 2 is an example in which an orthogonal pilot signal generated by a code inversion method is used. Here, the arrangement of pilot carriers in existing terrestrial digital broadcasting is used as it is, and description will be made based on an example in which a transmission frame is configured by data carriers, pilot carriers, etc. However, the arrangement of pilot signals is not limited to this. Absent.

  FIG. 2A shows an example of the arrangement of data symbols and pilot signals generated by the OFDM frame configuration unit 14 of the first transmission system (sometimes referred to as system 1). When the carrier interval after time direction interpolation is Dx and the symbol interval is Dy, the figure is an example of Dx = 3 and Dy = 4. In the next-generation terrestrial transmission system, many pilot signal arrangements (combinations of Dx and Dy) are prepared and can be selected. The arrangement of pilot signals can be specified for each layer.

  In the OFDM frame of FIG. 2A, SP signals are arranged every 12 carriers in the carrier (frequency) direction and every 4 symbols in the symbol (time) direction. In a row shifted by one symbol in the symbol (time) direction, SP signals are arranged with a shift of Dx (3 carriers) in the carrier (frequency) direction from the previous row. Further, a continuous CP (Continual Pilot) signal is arranged on the carrier at the end (right end) of the OFDM frame. As in FIG. 5, white squares indicate data symbols, and diagonally hatched squares indicate normal (multiplied by a coefficient of +1) pilot signals.

  On the other hand, the OFDM frame configuration unit 15 of the second transmission system (sometimes referred to as system 2) uses the same pilot carrier arrangement as the system 1 OFDM frame, but the pilot carrier at a predetermined position is code-inverted. (Phase inversion) is performed to construct a transmission frame. In other words, the second-system pilot signal is obtained by multiplying the first-system pilot signal by a coefficient +1 or -1.

  FIG. 2B shows an example of the arrangement of the 2 system data symbols and pilot signals. In the figure, white squares indicate data symbols, diagonal hatched squares indicate normal pilot signals (multiplier +1 multiplied by coefficient +1), and cross-hatched squares indicate sign inversion (1 system). The pilot signal obtained by multiplying the pilot signal by a factor of -1 is shown. The pilot signal arrangement of the OFDM frame in FIG. 2B is the same as the pilot signal arrangement of the first system, and the SP signal is every 12 carriers in the carrier (frequency) direction and every 4 carriers in the symbol (time) direction. In a row shifted by one symbol in the symbol (time) direction, SP signals are shifted by Dx in the carrier (frequency) direction from the previous row.

  In the figure, the symbol of the carrier at the beginning (first row) and the left end (first column) of the OFDM frame is normal (multiplication by a coefficient +1), and the symbol in the second row and fourth column is inverted (multiplication by a coefficient -1). Then, the symbol in the third row and the seventh column is made normal (multiplication by a coefficient +1), and the symbol in the fourth row and the tenth column is inverted (multiplication by a coefficient -1). Then, with the carrier-symbol space (4 rows and 12 columns) including the carrier at the beginning and the left end of this OFDM frame as a basic block, the code is alternately inverted in units of basic blocks in the carrier direction and the symbol direction and repeated. As a result, as shown in FIG. 2B, the SP signals alternately invert the phase in the symbol direction, the carrier direction, and further in the oblique direction.

  In the present invention, an orthogonal pilot signal is also used for the CP signal by the code inversion method. In FIG. 2B, with respect to the CP signal arranged on the carrier at the end (right end) of the OFDM frame, Dy symbols from the beginning of the OFDM frame are assumed to be normal (multiplication by a coefficient +1), and the following Dy The symbols are inverted (multiplied by a coefficient of -1), and thereafter the coefficients are switched for each Dy symbol. In other words, the sign of the CP signal is determined so as to maintain the sign inversion relationship (periodicity) of the SP signal. As a result, the CP signal can be used as a 2 system SP signal.

  Looking at the first (first row) symbol in FIG. 2B, the CP signal (+1) at the right end and the SP signal (−1) on the left side of 12 carriers from the right end are adjacent in the frequency direction at a predetermined interval. The relationship is the same as that of the SP signal, and the transmission path characteristic can be estimated by combining the CP signal and the SP signal. Looking only at the rightmost column, the leading CP signal (+1) and the CP signal (−1) below Dy (= 4) symbols from the leading edge are related to the relationship between SP signals adjacent in the time direction at predetermined intervals. It is the same (refer to the SP signal in the leftmost column), and the CP characteristics can be estimated by combining these CP signals. Further, the CP signal (−1) of the fifth symbol from the head and the SP signal (+1) of the fourth symbol from the head of the fourth carrier from the right end (fourth row of the fourth column from the right) are at a predetermined interval. This is the same as the relationship between SP signals adjacent in an oblique direction, and the transmission path characteristics can be estimated by combining this CP signal and SP signal. Similar diagonal adjacency relationships are established between all SP signals and CP signals in the fourth carrier from the right, and the transmission path characteristics can be estimated from these.

  Thus, in the present invention, the CP signal is determined so as to maintain the relationship (periodicity) of the sign inversion (that is, the multiplication coefficient) of the SP signal, and can be used as an SP signal. This is equivalent to increasing the SP signal, and the transmission path characteristics can be estimated more accurately than in the past. Conventionally, processing has been complicated when the SP signal and the CP signal are processed separately. However, in the present invention, the CP signal can also be processed uniformly by considering the CP signal as an SP signal in the receiving apparatus (for example, Since the transmission path characteristic estimation process performed between SP signals can be extended to the CP signal area and batch processing can be performed), the processing efficiency can be improved.

  Next, another example of each OFDM frame generated by the OFDM frame configuration units 14 and 15 will be described. FIG. 3 shows an example in which orthogonal pilot signals generated by the null method are used. The OFDM frame configuration unit 14 of the first transmission system uses, for example, the arrangement of pilot carriers in FIG. 2 as it is, but configures a transmission frame with pilot data at a predetermined position as null data (amplitude 0).

  FIG. 3A shows an example of the arrangement of data symbols and pilot signals in the first system. The figure shows an example of Dx = 3 and Dy = 4. In the figure, white squares indicate data symbols, diagonally hatched squares indicate normal pilot signals (multiplied by coefficient +1), and black squares indicate null data (pilot signals multiplied by coefficient 0). Yes.

  In the OFDM frame of FIG. 3A, SP signals are arranged every 12 carriers in the carrier (frequency) direction and every 4 symbols in the symbol (time) direction. In a row shifted by one symbol in the symbol (time) direction, SP signals are arranged with a shift of Dx (3 carriers) in the carrier (frequency) direction from the previous row. Further, a CP (Continual Pilot) signal is arranged on the carrier at the end (right end) of the OFDM frame.

  In FIG. 3A, the carrier symbol at the beginning (first row) and the left end (first column) of the OFDM frame is normal (multiplied by coefficient +1), and the symbol in the second row and fourth column is null data (coefficient 0). The symbol in the third row and the seventh column is normal (multiplication by a coefficient +1), and the symbol in the fourth row and the tenth column is null data (multiplication by a coefficient 0). Then, with reference to the carrier-symbol space (4 rows and 12 columns) including the carrier at the beginning and the left end of this OFDM frame, the SP signal has a coefficient +1 (normal) and a coefficient 0 (null) alternately in the carrier direction and the symbol direction. Multiply by. As a result, as shown in FIG. 3A, the normal (multiplier by coefficient +1) SP signal and the null data (multiplication by coefficient 0) SP signal are alternately arranged in the symbol direction, carrier direction, and diagonal direction. .

  In the present invention, a pilot signal generated by a null method is also used for the CP signal. In FIG. 3A, with respect to the CP signal arranged on the carrier at the end (right end) of the OFDM frame, Dy symbols from the beginning of the OFDM frame are assumed to be normal (multiplication by a coefficient +1), and the following Dy The symbol is null data (a pilot signal multiplied by coefficient 0), and then, for each Dy symbol, the CP signal is alternately multiplied by coefficient +1 and coefficient 0. As a result, the normal (coefficient + 1) CP signal and the null data (coefficient 0) CP signal are repeated Dy symbols for the CP signal.

  In the arrangement of FIG. 3A, the pilot signal of which the sign is inverted (multiplication by coefficient −1) in the pilot signal of FIG. 2B is replaced with a pilot signal of null data (multiplication by coefficient 0). Equal to the thing.

  The OFDM frame configuration unit 15 of the second transmission system uses the same pilot carrier arrangement as that of the 1-system OFDM frame, but is a normal pilot signal (multiplied by a coefficient +1) and a pilot signal of null data (multiplied by a coefficient 0). For, the coefficients (+1 and 0) are completely interchanged to form a transmission frame. FIG. 3B shows an example of the arrangement of 2 system data symbols and pilot signals. In the figure, white squares indicate data symbols, diagonally hatched squares indicate normal pilot signals (multiplied by coefficient +1), and black squares indicate null data (pilot signals multiplied by coefficient 0). Yes.

  In the OFDM frame of FIG. 3B, SP signals are arranged every 12 carriers in the carrier (frequency) direction and every 4 carriers in the symbol (time) direction, and shifted by one symbol in the symbol (time) direction. In the previous row, the SP signal is arranged with a deviation of Dx (= 3) in the carrier (frequency) direction from the previous row. In FIG. 3 (B), the carrier symbol at the beginning (first row) and left end (first column) of the OFDM frame is set as null data (multiplied by a coefficient 0). In the direction, the SP signal of null data (multiplication by coefficient 0) and the SP signal of normal (multiplication by coefficient +1) are alternately arranged.

  Further, for the CP signal, a pilot signal generated by the null method is used. That is, in the second system, as shown in FIG. 3B, with respect to the CP signal arranged on the carrier at the end (right end) of the OFDM frame, Dy symbols from the top of the OFDM frame are null data (multiplied by a coefficient 0). Pilot signal), the next Dy symbols are normal (multiplication by coefficient +1), and then the CP signal is alternately multiplied by coefficient 0 and coefficient +1 for each Dy symbol. As a result, the CP signal of null data (coefficient 0) and the normal (coefficient + 1) CP signal are repeated for each Dy symbol.

  As a result, the pilot signal of FIG. 3B is obtained by multiplying the pilot signal of FIG. 3A by the multiplication coefficient for the normal pilot signal (multiplication by coefficient +1) and the pilot signal of null data (multiplication by coefficient 0). It is equal to a complete replacement of (+1, 0).

  As described above, also in FIG. 3, the arrangement of normal CP signals and null data is determined so that the CP signal maintains the relationship (periodicity) of coefficient multiplication of +1 and 0 of the SP signal. As a result, the CP signal can be used as the SP signal. In each of the first and second systems, the code relationship between the CP signal and the adjacent SP signal (particularly, the adjacent code relationship in the oblique direction) is the same as the relationship between the other adjacent SP signals. The point that the SP signal (+1) and the null data (0) are opposite to each other in the system is also maintained in the CP signal. Thereby, the transmission path characteristics can be estimated by combining the CP signal and the SP signal.

  In the present invention, even when the null method is adopted, the multiplication coefficient (+1, 0) is determined so that the CP signal maintains the relationship (periodicity) of the multiplication coefficient of the SP signal. Since it can be used, it corresponds to substantially increasing the SP signal, and the transmission path characteristics can be estimated more accurately than in the past. Conventionally, when the SP signal and the CP signal are separately processed, the processing is complicated. However, in the present invention, the CP signal can be regarded as the SP signal and processed uniformly in the receiving apparatus. Can be made more efficient.

  The OFDM frame structure shown in FIGS. 2 and 3 includes SP signals distributed in predetermined symbol (time) intervals and carrier (frequency) intervals, and CP signals continuously arranged in predetermined frequency carriers. In the OFDM frame including the at least one OFDM frame, the SP signal is alternately multiplied by the first coefficient and the second coefficient in the symbol (time) direction and the carrier (frequency) direction, and the CP signal is CP. It can be said that the signal is alternately multiplied by the first coefficient and the second coefficient for each number corresponding to a predetermined symbol (time) interval.

  In the first embodiment, the configuration and operation of the transmission apparatus 10 have been described. However, the present invention is not limited to this, and is a semiconductor chip mounted on the transmission apparatus 10 and includes OFDM frame configuration units 14 and 15 and a pilot. You may comprise as a chip | tip which has a function of the signal generation part 16. FIG. That is, an OFDM frame that is installed in a transmission apparatus and includes SP signals that are distributed and distributed at predetermined symbol (time) intervals and carrier (frequency) intervals, and CP signals that are continuously allocated to predetermined frequency carriers. Corresponds to at least the SP signal obtained by alternately multiplying the first coefficient and the second coefficient in the symbol (time) direction and the carrier (frequency) direction, and the symbol (time) interval of the SP signal. It may be configured as a chip capable of creating an OFDM frame including a CP signal obtained by alternately multiplying the first coefficient and the second coefficient for each number to be processed.

  In this manner, a chip of a transmission apparatus that generates an OFDM signal including a CP signal whose code (multiplication coefficient) is determined so as to maintain the relationship (periodicity) of the code (multiplication coefficient) of the SP signal is configured. be able to.

  Further, in a chip equipped with a plurality of transmission systems and mounted on a transmission apparatus that transmits two types of OFDM signals, the first coefficient and the second coefficient are +1 and −1, and coefficient multiplication is performed in one OFDM frame. And coefficient multiplication is not performed in the other OFDM frame. Further, the first coefficient and the second coefficient are +1 and 0, and the coefficients to be multiplied with the SP signal or CP signal at the corresponding positions in the two types of OFDM frames can be reversed.

  Furthermore, although the configuration and operation of the transmission apparatus 10 have been described in the first embodiment, the present invention is not limited to this, and the transmission apparatus 10 may be configured as a transmission method that transmits OFDM signals using a plurality of transmission systems. That is, according to the data flow of FIG. 1, the step of performing error correction encoding processing on the transmitted data, the step of mapping the error correction encoded data on the IQ plane by a predetermined modulation scheme, and the mapped data Performs space-time coding processing, divides space-time coded data into two systems, and distributes to predetermined symbol (time) intervals and carrier (frequency) intervals based on the space-time coded data of each system Generating an OFDM frame that includes SP signals that are arranged in the same manner and CP signals that are continuously arranged in a predetermined frequency carrier, wherein the OFDM frame includes at least a symbol (time) direction and a carrier (frequency) direction. For each SP signal obtained by alternately multiplying the coefficient of 1 and the second coefficient and the number corresponding to the symbol (time) interval of the SP signal, the first coefficient and the second coefficient A plurality of transmissions comprising: creating an OFDM frame including CP signals alternately multiplied by coefficients; and inverse fast Fourier transforming the generated OFDM frame signal to generate a time-domain OFDM signal You may comprise as a transmission method which transmits an OFDM signal by a system | strain.

  Thus, a transmission method for transmitting an OFDM signal including a CP signal whose code (multiplication coefficient) is determined so as to maintain the relationship (periodicity) of the code (multiplication coefficient) of the SP signal may be configured. it can.

  According to the above chip and transmission method, it is possible to generate an OFDM signal that can more accurately estimate the transmission path characteristics without increasing the SP signal in the MIMO transmission method or the MISO transmission method.

(Embodiment 2)
Next, a receiving apparatus according to Embodiment 2 of the present invention will be described.

  FIG. 4 is a block diagram illustrating an example of a configuration of the receiving device. The receiving device 20 is a receiving device that can receive OFDM transmission signals of a plurality of systems, and includes receiving antennas Rx1, Rx2, FFT (Fast Fourier Transform) units 21, 22, a transmission path characteristic estimating unit 23, a space-time decoding unit 24, A demapping unit 25 and an error correction decoding unit 26 are provided. Here, a description will be given of a MIMO transmission system receiving apparatus with two receiving antennas and FFT units, but a MISO transmission receiving apparatus with one receiving system can be similarly configured.

  When the receiving antennas Rx1 and Rx2 of the receiving device 20 receive the OFDM signal transmitted by the transmitting device 10 of FIG. 1, after performing frequency conversion, GI (guard interval) removal processing, etc. (not shown), The received signals are output to the FFT units 21 and 22, respectively. Here, in the received OFDM signal transmitted from at least one transmission system, the first coefficient and the second coefficient (for example, +1 and −1) are alternately arranged in the symbol (time) direction and the carrier (frequency) direction. For each number corresponding to the multiplied SP signal and the symbol (time) interval of the SP signal, a CP signal that is alternately multiplied by the first coefficient and the second coefficient is included.

  The FFT units 21 and 22 receive the OFDM signal from which the GI has been removed as input, perform fast Fourier transform on the time domain OFDM signal, generate a frequency domain OFDM signal, and transmit the channel characteristic estimation unit 23 and the space-time decoding unit 24.

  The transmission path characteristic estimation unit 23 extracts pilot signals (SP, CP) from the OFDM signals converted into the frequency domains respectively input from the FFT units 21 and 22. Estimate the transmission path characteristics (transmission path response) of each pilot signal position based on the reception status (reception strength, phase, etc.) of the extracted pilot signal, and then perform other than the pilot signal position by an appropriate method such as interpolation processing. The channel characteristics at all symbol positions are estimated, and the estimated channel characteristics are output to the space-time decoding unit 24.

  In the present invention, the received CP signal has a code (multiplication coefficient) determined so as to maintain the relationship (periodicity) of the code (multiplication coefficient) of the SP signal. The CP signal is also used as the SP signal. That is, not only combinations of SP signals but also SP signals and CP signals are combined to estimate transmission path characteristics from a plurality of transmission systems. Note that it is desirable to treat the CP signal as an SP signal and process it uniformly.

  The space-time decoding unit 24 uses the OFDM signal data carrier and the transmission path characteristics based on the transmission path characteristics input from the transmission path characteristic estimation unit 23 and the OFDM signals converted into the frequency domain by the FFT units 21 and 22. The space-time decoding process is performed, and the space-time decoded data carrier (symbol) is output to the demapping unit 25. As the space-time decoding process, a decoding process corresponding to STBC or the like is performed.

  The demapping unit 25 receives the data carrier (symbol) subjected to space-time decoding from the space-time decoding unit 24, performs demapping (carrier demodulation) corresponding to the modulation scheme, and outputs the processing result to the error correction decoding unit 26 To do. As a modulation method, QPSK, 16QAM, 64QAM, 256QAM, 1024QAM, 4096QAM, or the like is used.

  The error correction decoding unit 26 receives the data demapped by the demapping unit 25 and performs error correction decoding processing corresponding to the error correction coding processing on the transmission side. If necessary, processing such as deinterleaving and energy despreading may be performed. The data subjected to the error correction decoding process is output as output data of the receiving device.

  In addition, although the receiving apparatus of Embodiment 2 was demonstrated as a receiving apparatus of a MIMO transmission system, even if it is a receiving apparatus corresponding to a MISO transmission system provided with a receiving antenna, an FFT unit, and a transmission path characteristic estimation unit. good.

  In the second embodiment, the configuration and operation of the receiving device 20 have been described. However, the present invention is not limited to this, and the semiconductor chip mounted on the receiving device 20 has the function of the transmission path characteristic estimating unit 23. You may comprise as a chip | tip which has. That is, in a chip mounted on a receiving apparatus, an SP signal obtained by alternately multiplying a first coefficient and a second coefficient in at least a symbol (time) direction and a carrier (frequency) direction, and a symbol ( For each number corresponding to a (time) interval, an OFDM signal including a CP signal obtained by alternately multiplying a first coefficient and a second coefficient is processed, and the SP signal and the CP signal are combined to transmit the plurality of transmissions. You may comprise as a chip | tip which can estimate the transmission-line characteristic from a system | strain. Further, in the chip mounted on the receiving apparatus, the process of estimating the transmission path characteristics may be uniformly processed by regarding the CP signal as an SP signal.

  In this way, in the chip of the receiving apparatus that receives the OFDM signal including the CP signal in which the code (multiplication coefficient) is determined so as to maintain the relationship (periodicity) of the code (multiplication coefficient) of the SP signal, It is possible to configure a chip that uses the signal as an SP signal to estimate the transmission path characteristics.

  In the second embodiment, the configuration and operation of the receiving apparatus 20 have been described. However, the present invention is not limited to this, and OFDM signals transmitted from a plurality of transmission systems are received, and transmission path characteristics are estimated. It may be configured as a receiving method for performing. That is, a step of receiving OFDM signals transmitted from a plurality of transmission systems according to the data flow of FIG. 4 and a step of generating a frequency-domain OFDM signal by performing fast Fourier transform on the received OFDM signals, A first coefficient is obtained for each SP signal obtained by alternately multiplying a first coefficient and a second coefficient in the (time) direction and the carrier (frequency) direction, and for each number corresponding to the symbol (time) interval of the SP signal. Generating an OFDM signal including a CP signal alternately multiplied by the second coefficient, and estimating transmission path characteristics from the plurality of transmission systems by combining the SP signal and the CP signal. And a step of performing space-time decoding processing based on the estimated transmission path characteristics and the OFDM signal converted into the frequency domain, and demapping the data symbols subjected to space-time decoding A step of carrier demodulation) process, and a step of performing an error correction decoding process on the demapped data, may be configured as a receiving method. In the step of estimating the transmission path characteristics in the receiving method, the CP signal may be regarded as an SP signal and processed uniformly.

  Thus, in a receiving method for receiving an OFDM signal including a CP signal whose code (multiplication coefficient) is determined so as to maintain the relationship (periodicity) of the code (multiplication coefficient) of the SP signal, A reception method that estimates the transmission path characteristics can also be configured by using the SP signal.

  According to the receiving apparatus, chip, and receiving method of the present invention, the transmission path characteristics can be estimated more accurately by using the CP signal as an SP signal in the MIMO transmission system or the MISO transmission system.

  Although the above embodiment has been described as a representative example, it will be apparent to those skilled in the art that many changes and substitutions can be made within the spirit and scope of the invention. Therefore, the present invention should not be construed as being limited by the above-described embodiments, and various modifications and changes can be made without departing from the scope of the claims. For example, a plurality of constituent blocks described in the embodiments can be combined into one, or one constituent block can be divided.

DESCRIPTION OF SYMBOLS 10 Transmission apparatus 11 Error correction encoding part 12 Mapping part 13 Space-time encoding part 14 OFDM frame structure part 15 OFDM frame structure part 16 Pilot signal generation part 17 IFFT part 18 IFFT part 20 Receiver 21 FFT part 22 FFT part 23 Transmission Path characteristic estimation unit 24 Space-time decoding unit 25 Demapping unit 26 Error correction decoding unit

Claims (9)

In a transmission device comprising a plurality of transmission systems and transmitting OFDM signals,
First and second constituting an OFDM frame including SP signals distributed in predetermined symbol (time) intervals and carrier (frequency) intervals and CP signals continuously arranged in predetermined frequency carriers OFDM frame configuration unit
In at least one OFDM frame configuration unit, the SP signal is alternately multiplied by a first coefficient and a second coefficient in a symbol (time) direction and a carrier (frequency) direction, and for the CP signal, A transmitting apparatus comprising: an OFDM frame in which a first coefficient and a second coefficient are alternately multiplied for each number corresponding to the predetermined symbol (time) interval.   2. The transmission apparatus according to claim 1, wherein an OFDM frame configured by the at least one OFDM frame configuration unit has a relationship (periodicity) between a first coefficient and a second coefficient in the SP signal as the CP. A transmission apparatus characterized by being maintained in a signal.   3. The transmission apparatus according to claim 1, wherein the first coefficient and the second coefficient are +1 and −1, multiplication is performed in one OFDM frame configuration section, and multiplication is performed in the other OFDM frame configuration section. There is no transmission device.   3. The transmission apparatus according to claim 1, wherein the first coefficient and the second coefficient are +1 and 0, and the first and second OFDM frame configuration units convert the SP signal or CP signal at the corresponding position. A transmitter characterized in that the coefficients to be multiplied are opposite. Generates an OFDM frame that is installed in a transmitter and includes SP signals distributed at predetermined symbol (time) intervals and carrier (frequency) intervals, and CP signals that are continuously arranged at predetermined frequency carriers. A chip to do,
At least for each SP signal obtained by alternately multiplying the first coefficient and the second coefficient in the symbol (time) direction and the carrier (frequency) direction, and for each number corresponding to the symbol (time) interval of the SP signal, A chip for generating an OFDM frame including a CP signal obtained by alternately multiplying a coefficient of 1 and a second coefficient. In a receiving apparatus that receives OFDM signals transmitted from a plurality of transmission systems,
An OFDM signal transmitted from at least one transmission system includes an SP signal obtained by alternately multiplying a first coefficient and a second coefficient in a symbol (time) direction and a carrier (frequency) direction, and a symbol ( For each number corresponding to a (time) interval, a CP signal that is alternately multiplied by a first coefficient and a second coefficient is included,
A receiver that estimates transmission path characteristics from the plurality of transmission systems by combining the SP signal and the CP signal.   The receiving apparatus according to claim 6, wherein the OFDM frame transmitted and received from the at least one transmission system has a relationship (periodicity) between the first coefficient and the second coefficient in the SP signal. A receiving apparatus characterized in that it is also maintained in a signal.   8. The receiving apparatus according to claim 6, wherein the process of estimating the transmission path characteristic is uniformly processed by regarding the CP signal as an SP signal. A chip mounted on a receiving device,
At least for each SP signal obtained by alternately multiplying the first coefficient and the second coefficient in the symbol (time) direction and the carrier (frequency) direction, and for each number corresponding to the symbol (time) interval of the SP signal, Processing an OFDM signal including a CP signal alternately multiplied by a coefficient of 1 and a second coefficient;
A chip characterized by estimating transmission path characteristics from a plurality of transmission systems by combining the SP signal and the CP signal.

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