JP4842892B2 - Transmission device and transmission method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform proper processing at a receiving side in digital broadcasting. <P>SOLUTION: This transmitter 11 transmits a modulated signal obtained by digitally modulating a symbol of a main signal and a symbol of a pilot signal used to compensate nonlinear distortion that occurs on a transmission path at a receiving side by a selection modulation system selected among BPSK, QPSK, 8PSK, 16APSK and 32APSK. An energy spreading part 42 selects an initial value associated with the selection modulation system among initial values of a spreading code respectively associated with BPSK, QPSK, 8PSK, 16APSK and 32APSK, uses the initial value, generates a spread code and performs energy spreading of the pilot signal. This invention is applicable, for example, to a transmitter for performing BS digital broadcasting. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to a transmission device and a transmission method, and more particularly, to a transmission device and a transmission method capable of performing appropriate processing on the reception side in digital broadcasting such as BS (Broadcasting Satellite) digital broadcasting. .

  Currently, the ISDB-S (Satellite Integrated Services. Digital Broadcasting) method is adopted for BS digital broadcasting, but in recent years, the ISDB-S method has been studied to be more advanced in order to perform larger capacity transmission. (For example, refer nonpatent literature 1).

  In the advancement of the ISDB-S system, transmission of a pilot signal in addition to the main signal is being studied. Here, the main signal is original information to be transmitted such as image data as a program, for example, and the pilot signal is a transmission path (transmission for transmitting a modulation signal) to a modulation signal obtained by performing digital modulation. This signal is used to compensate on the receiving side for non-linear distortion that occurs on the transmission path including the inside of the apparatus and the receiving apparatus that receives the modulated signal.

  Also, in the ISDB-S system, a modulation system that digitally modulates a main signal symbol is changed to BPSK (Binary Phase Shift Keying), QPSK (Quadrature Phase Shift Keying), and 8PSK (Phase Shift Keying) as a plurality of modulation systems. It is possible to select from three modulation schemes, but in the advanced ISDB-S scheme, there are five modulation schemes that add 16APSK (Amplitude Phase Shift Keying) and 32APSK to the above three modulation schemes. It has been studied to be able to select a modulation scheme for digitally modulating the main signal symbol.

  Here, in modulation including digital modulation, a modulated signal is obtained by modulating a carrier wave according to data (signal) to be transmitted. In this specification, for convenience of explanation, a carrier wave is Modulating according to target data is also referred to as modulating data to be transmitted.

Hashimoto, Yoichi Suzuki, Akihisa Suji, Shoji Tanaka, Kazuyoshi Masamoto, "A Study on Advanced ISDB-S", Proceedings of the 2007 IEICE General Conference, B-3-7, 2007.3

  The pilot signal used when the ISDB-S system is advanced is used to compensate the nonlinear distortion that occurs in the modulated signal on the transmission path on the receiving side. Therefore, the symbol of the pilot signal is the same as the symbol of the main signal. It is digitally modulated by the modulation method. Therefore, the pilot signal symbols are also digitally modulated by a modulation scheme selected from a plurality of modulation schemes in the same manner as the main signal symbols.

  On the other hand, in the ISDB-S system, in order to prevent energy (power) from concentrating on a specific frequency in the modulated signal, the main signal symbol is subjected to energy spreading processing, but a pilot signal is used. In this case, it is necessary to apply energy spreading processing to the pilot signal symbols.

  In the energy diffusion process, one of PRBS (Pseudorandom Binary Sequence), for example, an M sequence (maximal-length sequences) is generated with a predetermined value as an initial value, and the M sequence is used for energy diffusion. As a code, the symbol is multiplied.

  By the way, since the spreading code (sequence) becomes a different sequence if the initial value is different, if the initial value of the spreading code used for the energy spreading of the pilot signal symbol is an inappropriate value, the receiving side However, it may be difficult to perform appropriate processing.

  That is, for example, the PAPR (Peak-to-Average Power Ratio) of a modulation signal of a symbol (symbol of a pilot signal after energy spreading) obtained by energy spreading of the symbol of the pilot signal varies depending on the initial value of the spreading code. . Then, when the initial value of the spreading code that reduces the PAPR of the pilot signal is adopted, on the receiving side, depending on the pilot signal with a small PAPR, nonlinear distortion that occurs on the transmission path in the main signal with a large PAPR, It may happen that the receiver cannot properly compensate.

  On the other hand, when the PAPR is large, the frequency band of the modulation signal may be expanded due to nonlinear distortion generated in the modulation signal, and the use efficiency of the frequency band may be deteriorated.

  Also, for example, depending on the initial value of the spread code, the symbol values that can be taken by the symbols of the pilot signal after energy spread appear non-uniformly. In this way, when the symbol values that can be taken by the pilot signal appear unevenly, on the receiving side, depending on such pilot signal, nonlinear distortion of the symbol of the main signal that occurs on the transmission path is appropriately compensated on the receiving side. It can happen that it cannot be done.

  The present invention has been made in view of such a situation, and makes it possible to perform appropriate processing on the receiving side in digital broadcasting.

  A transmitting apparatus according to one aspect of the present invention compensates for a symbol of a main signal, which is information to be transmitted, and nonlinear distortion generated on a transmission line on a receiving side in a transmitting apparatus that transmits a modulated signal obtained by performing digital modulation. A modulation signal obtained by digitally modulating a symbol of a frame composed of a plurality of slots including at least one slot, and a symbol of the main signal, and the pilot signal used in order to A transmitter that transmits a modulation signal obtained by digitally modulating a signal symbol with a selected modulation method selected from a plurality of modulation methods, and associated with each of the plurality of modulation methods for energy spreading. Storage means for storing an initial value of PRBS (Pseudorandom Binary Sequence) as a spreading code to be used; Selecting means for selecting an initial value associated with the selected modulation scheme from among initial values associated with a plurality of modulation schemes stored in the storage means, and using the initial value, the spreading code And generating means for performing energy diffusion of symbols of the pilot signal using the spreading code.

  A transmission method according to one aspect of the present invention is a transmission method of a transmission apparatus that transmits a modulated signal obtained by performing digital modulation, and receives a main signal symbol that is information to be transmitted and nonlinear distortion that occurs on a transmission path. A modulation signal obtained by digitally modulating a symbol of a frame composed of a plurality of slots including at least one slot with a symbol of a pilot signal used for compensation on the side, the symbol of the main signal, And a transmission method of a transmitting apparatus for transmitting a modulation signal obtained by digitally modulating the pilot signal symbol by a selective modulation method selected from a plurality of modulation methods, each corresponding to the plurality of modulation methods In addition, a plurality of stored in the storage means for storing the initial value of the spreading code used for energy spreading The initial value associated with the selected modulation scheme is selected from the initial values associated with the modulation scheme, the spreading code is generated using the initial value, the spreading code is used, Performing energy spreading of pilot signal symbols.

  In one aspect of the present invention, a plurality of symbols including a main signal symbol that is information to be transmitted and a pilot signal symbol used to compensate for nonlinear distortion occurring on the transmission path on at least one slot. A modulation signal obtained by digitally modulating a symbol of a frame composed of slots, wherein the main signal symbol and the pilot signal symbol are selected according to a selected modulation method selected from a plurality of modulation methods. A modulated signal obtained by digital modulation is transmitted. At this time, an initial value associated with the selected modulation scheme is selected from among initial values associated with a plurality of modulation schemes, and the spreading code is generated using the initial values. Then, the spread of the pilot signal symbols is performed using the spreading code.

  According to an aspect of the present invention, appropriate processing can be performed on the receiving side in digital broadcasting.

  Embodiments of the present invention will be described below. Correspondences between the constituent elements of the present invention and the embodiments described in the specification or the drawings are exemplified as follows. This description is intended to confirm that the embodiments supporting the present invention are described in the specification or the drawings. Therefore, even if there is an embodiment that is described in the specification or the drawings but is not described here as an embodiment that corresponds to the constituent elements of the present invention, that is not the case. It does not mean that the form does not correspond to the constituent requirements. Conversely, even if an embodiment is described here as corresponding to a configuration requirement, that means that the embodiment does not correspond to a configuration requirement other than the configuration requirement. Not something to do.

A transmission device according to one aspect of the present invention includes:
In a transmission device (for example, the transmission device 11 in FIG. 3) that transmits a modulation signal obtained by performing digital modulation,
A symbol of a frame composed of a plurality of slots including at least one slot including a symbol of a main signal that is information to be transmitted and a symbol of a pilot signal used to compensate nonlinear distortion occurring on the transmission path on the receiving side A modulation signal obtained by digitally modulating the symbol of the main signal and the symbol of the pilot signal by digital modulation using a selected modulation method selected from a plurality of modulation methods A transmission device for transmitting a signal;
A storage unit (for example, an initial value storage unit 110 in FIG. 4) that stores an initial value of PRBS (Pseudorandom Binary Sequence) as a spreading code used for energy spreading in association with each of the plurality of modulation schemes;
Selecting means (for example, selector 116 in FIG. 4) for selecting an initial value associated with the selected modulation method;
Generating means for generating the spreading code using the initial value (for example, the spreading code generator 61 in FIG. 4);
Spreading means (for example, a spreading unit 65 in FIG. 4) that spreads the energy of symbols of the pilot signal using the spreading code.

In one aspect of the transmitter,
An initial value setting unit (for example, an initial value setting unit 63 in FIG. 4) for setting the initial value in the generating unit in one frame cycle or one slot cycle may be further provided.

In one aspect of the transmitter,
A storage value setting unit (for example, a stored value setting unit 117 in FIG. 4) for rewriting the initial value stored in the storage unit by setting an initial value in the storage unit can be further provided.

A transmission method according to one aspect of the present invention includes:
In a transmission method of a transmission apparatus (for example, the transmission apparatus 11 in FIG. 3) that transmits a modulated signal obtained by performing digital modulation,
A symbol of a frame composed of a plurality of slots including at least one slot including a symbol of a main signal that is information to be transmitted and a symbol of a pilot signal used to compensate nonlinear distortion occurring on the transmission path on the receiving side A modulation signal obtained by digitally modulating the symbol of the main signal and the symbol of the pilot signal by digital modulation using a selected modulation method selected from a plurality of modulation methods A transmission method of a transmission device that transmits a signal,
Corresponding to the selected modulation method from among the initial values associated with the plurality of modulation methods stored in the storage means for storing the initial value of the spreading code used for energy spreading in association with each of the plurality of modulation methods Select the attached initial value (for example, step S11 in FIG. 5),
The spreading code is generated using the initial value (for example, step S13 in FIG. 5),
The spread code is used to spread the energy of the symbols of the pilot signal (for example, step S14 in FIG. 5).
Includes steps.

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

  FIG. 1 shows an embodiment of a broadcasting system to which the present invention is applied (a system is a logical collection of a plurality of devices, regardless of whether or not each component device is in the same housing). The example of a structure of the form is shown.

  In FIG. 1, the broadcasting system includes a transmission device 11 and a reception device 12.

  The transmission device 11 is a transmission device for BS digital broadcasting, for example, and transmits a modulation signal obtained by digitally modulating a carrier wave according to a symbol. The modulated signal transmitted by the transmission device 11 is received by a satellite (not shown), is subjected to necessary processing, and is transmitted.

  The receiving device 12 is a receiving device for BS digital broadcasting, for example, and receives a modulated signal transmitted from the transmitting device 11 via a satellite.

  FIG. 2 shows a format of a modulated signal transmitted by the transmission apparatus 11 of FIG.

  The transmission apparatus 11 selects a modulation scheme for digitally modulating a carrier from among five modulation schemes, for example, BPSK, QPSK, 8PSK, 16APSK, and 32APSK, and transmits the modulated modulation scheme. The symbol of interest is digitally modulated.

  Therefore, the transmission device 11 transmits a modulation signal of a modulation method selected from BPSK, QPSK, 8PSK, 16APSK, and 32APSK.

  Here, the modulation scheme selected from BPSK, QPSK, 8PSK, 16APSK, and 32APSK is also hereinafter referred to as a selective modulation scheme as appropriate.

  The transmission device 11 transmits symbols in units called frames.

  The frame includes a plurality of 120 slots # 1 to # 120.

  Slot #i (i = 1, 2,..., 120) starts from the beginning with 24 symbols of the unique sync signal Sync, 32 symbols of the pilot signal P, and 136 sets of the main signal Data # n of 66 sets. A set of symbols and four symbols of a TMCC (Transmission Multiplexing Configuration Control) signal T is sequentially arranged, and is therefore composed of 9296 (= 24 + 32 + (136 + 4) × 66) symbols.

  Here, in FIG. 2, the slot length (slot period) is 0.286296 milliseconds. Therefore, the frame length (frame period) is 34.3554 milliseconds (= 0.286296 milliseconds × 120 slots).

  The symbol of the synchronization signal Sync in the slot #i is a unique and known BPSK-modulated symbol and is used in the receiving apparatus 12 to establish synchronization.

  There are two types of synchronization signal Sync, signals Sync1 and Sync2. The symbol of the signal Sync1 is arranged in the first slot # 1 constituting the frame, and the symbol of the signal Sync2 is arranged in the second slot # 2 from the beginning. In the third and subsequent slots # 3 to # 120 from the top, the symbol of the signal Sync1 and the symbol of the signal! Sync2 obtained by inverting the signal Sync2 are alternately arranged.

  Here, the head of the slot can be detected by the symbol of the signal Sync1, Sync2, or! Sync2 arranged at the head of the slot. Further, the head of the frame can be detected by the set of the symbol of the signal Sync1 arranged in the first slot # 1 of the frame and the symbol of the signal Sync2 arranged in the second slot # 2 from the beginning.

  The symbol of the pilot signal P is used to compensate the nonlinear distortion generated in the modulated signal on the transmission path between the transmission apparatus 11 and the reception apparatus 12 by the reception apparatus 12 as the reception side. , QPSK, 8PSK, 16APSK, and 32APSK are digitally modulated by the same modulation scheme (selective modulation scheme) as the symbol of the main signal Data # n.

  Here, as 32 symbols of pilot signal P, symbol values that can be taken by symbols of the selective modulation scheme are sequentially arranged.

  That is, when the selection modulation method is BPSK (when the symbol of pilot signal P is BPSK modulated), the 32 symbols of pilot signal P include two symbol values 0b and 1b that can be taken by the BPSK symbol. Is repeated 16 times. Here, b represents that the previous value is a binary number.

  When the selected modulation scheme is QPSK, as the 32 symbols of the pilot signal P, four symbol values 00b, 01b, 10b, and 11b that can be taken by the QPSK symbol are repeatedly arranged 8 times.

  Further, when the selective modulation scheme is 8PSK, the 32 symbols of the pilot signal P include eight symbol values 000b, 001b, 010b, 011b, 100b, 101b, 110b, and 111b that can be taken by the 8PSK symbol. Repeated only 4 times.

  Similarly, when the selected modulation scheme is 16APSK, as the 32 symbols of pilot signal P, 0000b to 1111b, which are 16 symbol values that 16APSK symbols can take, are repeatedly arranged only twice. Also, when the selected modulation scheme is 32APSK, as 32 symbols of pilot signal P, 00000b to 11111b, which are 32 symbol values that can be taken by 32APSK symbols, are arranged only once.

  The symbol of the main signal Data # n is a symbol of original information to be transmitted, such as image data and audio data, and is selected from five modulation schemes BPSK, QPSK, 8PSK, 16APSK, and 32APSK Digital modulation is performed by a modulation method (selective modulation method).

  Here, the modulation scheme (selective modulation scheme) of the main signal Data # n is selected based on, for example, the data rate of the main signal Data # n. That is, for example, when the data rate of the main signal Data # n is low, for example, BPSK among BPSK, QPSK, 8PSK, 16APSK, and 32APSK is selected as the selective modulation method. For example, when the data rate of the main signal Data # n is high, 32PPSK, for example, among BPSK, QPSK, 8PSK, 16APSK, and 32APSK is selected as the selective modulation method.

  Note that the modulation scheme of the symbols of the main signal Data # n (and therefore the modulation scheme of the symbols of the pilot signal P) can be selected for each slot.

  The TMCC signal T is control information including the modulation method and coding method of the main signal in the modulation signal, and the symbol of the TMCC signal T is BPSK modulated. The symbol of the TMCC signal T can be decoded on a frame-by-frame basis. In the receiving apparatus 12, the symbol (pilot signal P) of the main signal Data # n in the modulated signal is obtained by the TMCC signal obtained by decoding the symbol of the TMCC signal T. The main signal Data # n can be demodulated.

  Next, FIG. 3 is a block diagram illustrating a configuration example of the transmission device 11 of FIG.

  The synchronization signal output unit 31 outputs a synchronization signal (signals Sync1, Sync2,! Sync2 in FIG. 2). The synchronization signal output from the synchronization signal output unit 31 is supplied to the mapping unit 36.

  The TMCC output unit 32 outputs a TMCC signal. The TMCC signal output from the TMCC output unit 32 is supplied to the mapping unit 37.

  The main signal output unit 33 outputs a main signal. The main signal output from the main signal output unit 33 is supplied to the mapping unit 38.

  The pilot signal output unit 34 outputs a pilot signal having the symbol value described with reference to FIG. 2 according to the selected modulation method represented by the selection information supplied from the modulation method selection unit 35. The pilot signal output from the pilot signal output unit 34 is supplied to the mapping unit 39.

  The modulation scheme selection unit 35 selects a modulation scheme that modulates the main signal (symbol thereof) from the five modulation schemes BPSK, QPSK, 8PSK, 16APSK, and 32APSK as the selected modulation scheme. Further, the modulation scheme selection unit 35 supplies selection information representing the selected modulation scheme to the pilot signal output unit 34, the mapping units 38 and 39, and the energy spreading unit 42.

  Here, for example, according to the bit rate of the main signal, the modulation method selection unit 35 selects a modulation method capable of transmitting the main signal of the bit rate as the selective modulation method.

  The mapping unit 36 converts the synchronization signal supplied from the synchronization signal output unit 31 into an IQ plane (IQ constant) defined by an I axis representing the I component in phase with the carrier wave and a Q axis representing the Q component orthogonal to the carrier wave. The symbol is converted into a symbol (symbol value) represented by the BPSK signal point on the data), and the symbol is mapped (converted) to the BPSK signal point and supplied to the multiplexing unit 43.

Here, since there are two BPSK signal points and can represent 2 (= 2 ¹ ) values (symbol values), one bit of the synchronization signal is converted into one symbol for the synchronization signal. Symbolized.

  The mapping unit 37 converts the TMCC signal supplied from the TMCC output unit 32 into a symbol represented by a BPSK signal point on the IQ plane, further maps the symbol to a BPSK signal point, and an energy spreading unit 40.

  Here, also with respect to the TMCC signal, one bit of the TMCC signal is symbolized into one symbol, similarly to the synchronization signal.

  The mapping unit 38 symbolizes the main signal supplied from the main signal output unit 33 into a symbol represented by the signal point of the selected modulation method represented by the selection information supplied from the modulation method selection unit 35 on the IQ plane. The symbol is mapped to the signal point of the selective modulation method and supplied to the energy spreading unit 41.

That is, in the mapping unit 38, when the selective modulation method is BPSK, there are two BPSK signal points and can represent 2 (= 2 ¹ ) values. One symbol is symbolized.

Further, in the mapping unit 38, when the selected modulation method is QPSK, the number of QPSK signal points is 4, and 4 (= 2 ² ) values can be represented. One symbol is symbolized. Further, in the mapping unit 38, when the selective modulation scheme is 8PSK, there are 8 8PSK signal points and 8 (= 2 ³ ) values can be represented. One symbol is symbolized. Further, in the mapping unit 38, when the selective modulation method is 16APSK, there are 16 16APSK signal points, and 16 (= 2 ⁴ ) values can be represented. One symbol is symbolized. Further, in the mapping unit 38, when the selective modulation method is 32APSK, the number of 32APSK signal points is 32 and can represent 32 (= 2 ⁵ ) values. One symbol is symbolized.

  The mapping unit 39 converts the pilot signal supplied from the pilot signal output unit 34 to a signal point of the selected modulation method represented by the selection information supplied from the modulation method selection unit 35 on the IQ plane, like the mapping unit 38. The symbol is converted into a symbol to be represented, and the symbol is mapped to a signal point of the selective modulation method and supplied to the energy spreading unit 41.

  The energy spreading unit 40 applies energy spreading processing to the symbols of the TMCC signal supplied from the mapping unit 37 (I component and Q component of the mapped signal point) using PRBS (Pseudorandom Binary Sequence) as a spreading code. The symbol of the TMCC signal subjected to the energy spreading is supplied to the multiplexing unit 43.

  The energy spreading unit 41 applies energy spreading processing to the main signal symbols supplied from the mapping unit 38 using PRBS as a spreading code, and supplies the energy-spread main signal symbols to the multiplexing unit 43. .

  The energy spreading unit 42 applies energy spreading processing to the pilot signal symbols supplied from the mapping unit 39 using PRBS as a spreading code, and supplies the pilot signal symbols after energy spreading to the multiplexing unit 43. .

  The energy spreading unit 42 generates PRBS as a spreading code using the initial value in the energy spreading process. In the energy spreading unit 42, the initial value used for generating the spread code is set according to the selected modulation scheme represented by the selection information supplied from the modulation scheme selection unit 35.

  The multiplexing unit 43 includes a synchronization signal symbol supplied from the mapping unit 36, a TMCC signal symbol supplied from the energy spreading unit 40, a main signal symbol supplied from the energy spreading unit 41, and an energy spreading unit 42. By multiplexing the symbols of the pilot signal to be supplied, a frame including 120 slots as shown in FIG. 2 and a plurality of 120 slots is formed and supplied to the transmission filter 44.

  The transmission filter 44 limits the frequency band of the symbol series of the symbols constituting the frame from the multiplexing unit 43 to a frequency band corresponding to a predetermined symbol rate (32.47 Mbaud in FIG. 2). Is supplied to the quadrature modulation unit 45.

  The quadrature modulation unit 45 performs BPSK modulation, QPSK modulation, 8PSK modulation, 16APSK modulation, or 32APSK modulation on a predetermined carrier wave in accordance with a frame (constituting symbols) from the transmission filter 44, and displays a modulation signal obtained as a result. Amplified by a non-linear amplifier (not shown) and transmitted.

  In the transmission apparatus 11 configured as described above, the modulation method selection unit 35 selects a modulation method for modulating the main signal from among the five modulation methods BPSK, QPSK, 8PSK, 16APSK, and 32APSK. The selected information indicating the selected modulation method is supplied to the pilot signal output unit 34, the mapping units 38 and 39, and the energy spreading unit 42.

  On the other hand, the mapping unit 36 maps the symbol of the synchronization signal supplied from the synchronization signal output unit 31 to the BPSK signal point, and supplies it to the multiplexing unit 43.

  The mapping unit 37 maps the symbol of the TMCC signal supplied from the TMCC output unit 32 to the BPSK signal point on the IQ plane and supplies the BPSK signal symbol to the energy spreading unit 40. Further, the mapping unit 38 maps the symbol of the main signal supplied from the main signal output unit 33 to the signal point of the selected modulation method represented by the selection information supplied from the modulation method selection unit 35 on the IQ plane, The energy diffusion unit 41 is supplied.

  Further, the mapping unit 39 selects the symbol of the pilot signal supplied from the pilot signal output unit 34, as in the mapping unit 38, by the selection modulation method represented by the selection information supplied from the modulation method selection unit 35 on the IQ plane. And is supplied to the energy diffusion unit 42.

  The energy spreading unit 40 performs energy spreading processing on the symbol of the TMCC signal supplied from the mapping unit 37 and supplies the symbol to the multiplexing unit 43. In addition, the energy spreading unit 41 performs energy spreading processing on the main signal symbol supplied from the mapping unit 38 and supplies the symbol to the multiplexing unit 43.

  The energy spreading unit 42 sets an initial value used for generating a spreading code in accordance with the selected modulation scheme represented by the selection information supplied from the modulation scheme selecting unit 35, and generates a spreading code using the initial value. . Further, the energy spreading unit 42 performs energy spreading processing on the symbols of the pilot signal supplied from the mapping unit 39 using the spreading code, and supplies the result to the multiplexing unit 43.

  The multiplexing unit 43 includes a synchronization signal symbol supplied from the mapping unit 36, a TMCC signal symbol supplied from the energy spreading unit 40, a main signal symbol supplied from the energy spreading unit 41, and an energy spreading unit 42. By multiplexing the symbols of the supplied pilot signal, the slot and the frame shown in FIG. 2 are formed and supplied to the orthogonal modulation unit 45 via the transmission filter 44.

  The orthogonal modulation unit 45 digitally modulates the symbols constituting the frame from the multiplexing unit 43 with BPSK, QPSK, 8PSK, 16APSK, or 32APSK, and amplifies and transmits the resulting modulation signal.

  FIG. 4 shows a configuration example of the energy diffusing unit 42 of FIG.

  The energy spreading unit 42 includes a spreading code generation unit 61, an initial value output unit 62, an initial value setting unit 63, a level conversion unit 64, and a spreading unit 65, and as described above, a pilot supplied from the mapping unit 39. Energy diffusion processing is performed on the signal symbols.

That is, the spread code generating unit 61 is composed of 15 selectors 101 ₁ to 101 ₁₅ , 15 latch circuits (D) 102 ₁ to 102 ₁₅ , and one EXOR gate 103. A 15th order M-sequence (maximal-length sequences) represented by X ¹⁵ + X ¹⁴ +1 is generated and supplied to the level converter 64.

Specifically, the spread code generator 61 includes a set of 15 sets of selectors 101 _k (k = 1, 2,..., 15) and a latch circuit 102 _k connected in series. a value latch circuit 102 ₁₅ is latched, and the value preceding the latch circuit 102 ₁₄ one is latched, via the EXOR gate 103 is configured to be fed back to the beginning of the selector 101 ₁ ing.

The selector 101 _k has first and second input terminals. The initial value of the M series is supplied from the initial value output unit 62 to the first input terminal, and the second input terminal receives the previous stage. The value latched by the latch circuit 102 _k-1 (provided that the output of the EXOR gate 103 is supplied to the _first selector 101 ₁ ) is supplied.

The selector 101 _k is supplied with an initialization signal from the initial value setting unit 63.

In accordance with the initialization signal from the initial value setting unit 63, the selector 101 _k is one bit of the M-sequence initial value supplied from the initial value output unit 62 to the first input terminal, or the latch circuit 102 _{k in the} previous stage. _-1 (however, for the _first selector 1011, the EXOR gate 103) supplies the second input terminal and the 1-bit value latched by the preceding latch circuit _102k-1 (however, the first for the selector 101 ₁ selects one of the bit output of the EXOR gate 103) to the subsequent stage of the latch circuit 102 _k.

The latch circuit 102 _k latches the value supplied from the preceding selector 101 _k and supplies it to the second input terminal of the succeeding selector 101 _{k + 1} . However, the latch circuit 102 ₁₅ of the final stage, supplies the values latched, as well as supplied to one input terminal of the two input terminals of the EXOR gate, as spreading codes, the level converter 64.

In EXOR gate 103, as described above, to one input terminal of its two input terminals, in addition to the value latch circuit 102 ₁₅ of the final stage is latched is supplied to the other input terminal, final the value preceding the latch circuit 102 ₁₄ stages of the latch circuit 102 ₁₅ is latched and is supplied.

EXOR gate 103, an exclusive OR of the values supplied to the one input terminal, a value latch circuit 102 ₁₅ is latched is supplied to the other input terminal, the latch circuit 102 ₁₄ is latched And the result of the calculation is supplied to the second input terminal of the _first selector 101 ₁ .

Here, when the initialization signal from the initial value setting unit 63 is, for example, the L level which is one of the H (High) and L (Low) levels, the selector 101 _k is the latch circuit 102 in the previous stage. _{The value} supplied from the _k-1 to the second input terminal and latched by the preceding latch circuit 102 _k-1 (however, the _first selector 101 ₁ is supplied from the EXOR gate 103 to the second input terminal. is the, selects the output of the EXOR gate 103) to the subsequent stage of the latch circuit 102 _k.

In addition, when the initialization signal from the initial value setting unit 63 is the H level, which is the other of the H or L levels, the M-sequence is supplied from the initial value output unit 62 to the first input terminal. The initial value is selected and supplied to the latch circuit 102 _k at the subsequent stage. As a result, the values latched by the latch circuits 102 ₁ to 102 ₁₅ are initialized to M-series initial values.

  The initial value output unit 62 includes an initial value storage unit 110, a selector 116, and a stored value setting unit 117, and is associated with each of BPSK, QPSK, 8PSK, 16APSK, and 32APSK as a plurality of modulation schemes. The initial value associated with the selected modulation scheme is selected from the initial code values and supplied to the spread code generator 61.

  That is, the initial value storage unit 110 includes the BPSK initial value storage unit 111, the QPSK initial value storage unit 112, the 8PSK initial value storage unit 113, the 16APSK initial value storage unit 114, and the 32APSK initial value storage unit 115. The initial value of the spreading code is stored in association with each of BPSK, QPSK, 8PSK, 16APSK, and 32APSK.

  Here, the BPSK initial value storage unit 111 stores a 15-bit value (BPSK initial value) used as the initial value of the spreading code when the selected modulation scheme is BPSK. The QPSK initial value storage unit 112 stores a 15-bit value (QPSK initial value) used as an initial value of a spreading code when the selected modulation scheme is QPSK, and the 8PSK initial value storage unit 113 When the selective modulation method is 8PSK, a 15-bit value (8PSK initial value) used as an initial value of the spreading code is stored. Similarly, the 16APSK initial value storage unit 114 stores a 15-bit value (16APSK initial value) used as the initial value of the spread code when the selected modulation scheme is 16APSK, and the 32APSK initial value storage unit. 115 stores a 15-bit value (32APSK initial value) used as the initial value of the spreading code when the selected modulation scheme is 32APSK.

  Selection information is supplied to the selector 116 from the modulation method selection unit 35 (FIG. 3).

  The selector 116 selects an initial value associated with the selected modulation scheme based on the selected modulation scheme represented by the selection information from the modulation scheme selection section 35, and outputs it to the spreading code generation section 61.

  That is, the selector 116 selects the BPSK initial value stored in the BPSK initial value storage unit 111 when the selected modulation method is BPSK. The selector 116 selects the initial value for QPSK stored in the initial value storage unit 112 for QPSK when the selected modulation method is QPSK, and the initial value for 8PSK when the selected modulation method is 8PSK. The initial value for 8PSK stored in the value storage unit 113 is selected. Further, the selector 116 selects the 16APSK initial value stored in the 16APSK initial value storage unit 114 when the selected modulation method is 16APSK, and the 32APSK initial value when the selected modulation method is 32APSK. The 32APSK initial value stored in the value storage unit 115 is selected.

  The stored value setting unit 117 is a BPSK initial value storage unit 111, a QPSK initial value storage unit 112, an 8PSK initial value storage unit 113, and a 16APSK initial configuration that constitute the initial value storage unit 110 in accordance with an external command. A 15-bit value serving as an initial value for BPSK, an initial value for QPSK, an initial value for 8PSK, an initial value for 16APSK, and an initial value for 32APSK for the value storage unit 114 and the initial value storage unit 115 for 32APSK, respectively. Set.

  Therefore, the BPSK initial value storage unit 111, the QPSK initial value storage unit 112, the 8PSK initial value storage unit 113, the 16APSK initial value storage unit 114, and the 32APSK initial value storage unit 115 are stored. , The initial value for QPSK, the initial value for 8PSK, the initial value for 16APSK, and the initial value for 32APSK can be rewritten by an external command.

  The command from the outside can be given from, for example, a control microcomputer (not shown) that controls the transmission device 11.

The initial value setting unit 63 includes a counter 121 and sets the values of the latch circuits 102 ₁ to 102 _{15 included in} the spreading code generation unit 61 to the initial values output by the selector 116 of the initial value output unit 62.

  That is, the counter 121 counts a clock synchronized with a symbol, and when the count value becomes a value corresponding to a frame period, for example, the counter 121 resets the count value and repeats counting a predetermined clock.

The initial value setting unit 63 supplies an L-level initialization signal to the selectors 101 ₁ to 10 ₁₅ of the spread code generating unit 61 except when the count value of the counter 121 is reset. Also, the initial value setting unit 63 supplies an H level initialization signal to the selectors 101 ₁ to 101 ₁₅ of the spread code generating unit 61 when the count value of the counter 121 is reset, whereby the frame period At the beginning of the frame, the initial value output from the initial value output unit 62 is set in the latch circuits 102 ₁ to 102 ₁₅ of the spread code generating unit 61.

Here, as described above, the initial value output from the initial value output unit 62 is a 15-bit value. The k-th bit from the MSB (Most Significant Bit) of the 15-bit value selects the selector 101 _k . Via the latch circuit 102 _k .

In the counter 121, the count value can be reset when the count value becomes a value corresponding to the slot period, not when the count value becomes a value corresponding to the frame period. In this case, the initial value output from the initial value output unit 62 is set in the latch circuits 102 ₁ to 102 ₁₅ of the spread code generating unit 61 in the slot period (the head of the slot).

The level converting unit 64 performs level conversion of the spreading code (bits) supplied from the spreading code generating unit 61 (the latch circuit 102 ₁₅ thereof) and supplies the level to the spreading unit 65.

  That is, when the spreading code (bit) supplied from the spreading code generating unit 61 is 0 or 1 of 1, the level converting unit 64 performs level conversion of the 1 bit to −1, and the spreading unit 65. In addition, when the spreading code (bit) supplied from the spreading code generator 61 is 0 of 0 or 1, the level converter 64 performs level conversion of the 0 bit to 1 (+1). , Supplied to the diffusion unit 65.

  The spreading unit 65 includes arithmetic units 131 and 132, and multiplies the symbols of the pilot signal supplied from the mapping unit 39 (FIG. 3) by the spreading code after level conversion from the level converting unit 64. , Energy dispersion of pilot signal symbols is performed.

  That is, the I component of the pilot signal symbol (the signal point to which the pilot signal is mapped) is supplied to the arithmetic unit 131, and the Q component of the pilot signal symbol (the signal point to which the pilot signal is mapped) is supplied to the arithmetic unit 132. Is done.

  The arithmetic unit 131 multiplies the I component of the symbol of the pilot signal by the spreading code from the level converting unit 64, and uses the resulting value as the I component (I ′) of the symbol after energy spreading, to the multiplexing unit 43 (FIG. 3).

  The arithmetic unit 132 multiplies the Q component of the pilot signal symbol by the spreading code from the level converting unit 64, and uses the resulting value as the Q component (Q ′) of the symbol after energy spreading. 43 (FIG. 3).

  Next, with reference to the flowchart of FIG. 5, the energy spreading process performed on the pilot signal symbols performed by the energy spreading unit 42 of FIG. 4 will be described.

  The energy diffusion unit 42 is supplied with selection information from the modulation scheme selection unit 35 (FIG. 3), and the selection information is supplied to the selector 116 of the initial value output unit 62.

  In step S11, the selector 116 selects an initial value associated with the selected modulation scheme represented by the selection information from the modulation scheme selection section 35 from among the initial values stored in the initial value storage section 110, and spread code Supply to the generator 61.

  On the other hand, in the initial value setting unit 63, the counter 121 counts the clock, and when the count value reaches a value corresponding to the frame period, the count value is reset and the predetermined clock is counted. The initial value setting unit 63 supplies an L-level initialization signal to the spread code generation unit 61 except when the count value of the counter 121 is reset.

Then, when the count value of the counter 121 is reset, the process proceeds from step S11 to step S12, and the initial value setting unit 63 supplies the H level initialization signal to the spreading code generation unit 61, thereby The initial value output from the initial value output unit 62 is set in the latch circuits 102 ₁ to 102 ₁₅ of the spread code generating unit 61 at the beginning of the frame.

Thereafter, the process proceeds from step S12 to step S13, and the spread code generator 61 starts generating an M-sequence using the initial values set in the latch circuits 102 ₁ to 102 ₁₅ in the immediately preceding step S12. The process proceeds to step S14.

  Here, the M sequence that has been generated in step S13 is supplied from the spread code generator 61 to the spreader 65 via the level converter 64.

  In step S14, the spreading unit 65 starts the generation in the immediately preceding step S13, and uses the M sequence sequentially supplied from the spreading code generating unit 61 via the level converting unit 64 as a symbol of the pilot signal from the mapping unit 39. By starting multiplication, the pilot signal symbols are subjected to energy spreading, and the pilot signal symbols after the energy spreading are supplied to the multiplexing unit 43 (FIG. 3).

  And a process returns to step S11 from step S14, and the same process is repeated hereafter.

In FIG. 5, the initial value output from the initial value output unit 62 is set in the latch circuits 102 ₁ to 102 ₁₅ of the spread code generating unit 61 at the start timing of the frame. The initial value output by 62 can be set in the latch circuits 102 ₁ to 102 _{15 at} the timing of the beginning of the slot as described above.

  Next, FIG. 6 is a block diagram illustrating a configuration example of the receiving device 12 of FIG.

  The orthogonal demodulation unit 201 is supplied with the modulation signal from the transmission device 11. The quadrature demodulation unit 201 multiplies the modulation signal from the transmission device 11 by a carrier wave (ideally) the same as the carrier wave used in the transmission device 11, thereby converting the modulation signal into an I component and a Q component. The demodulated signal of the format described in FIG. 3 is orthogonally demodulated and supplied to the synchronization unit 202.

  The synchronization unit 202 establishes synchronization such as symbol synchronization, frame synchronization, carrier wave synchronization, and the like based on the symbol of the synchronization signal in the demodulated signal from the orthogonal demodulation unit 201, and sends the synchronized demodulated signal to the error correction decoding unit 205. Supply.

  Further, the synchronization unit 202 supplies a synchronization pulse representing the head of the frame or slot to the energy despreading unit 203 after the synchronization is established.

  The synchronization unit 202 also extracts a pilot signal symbol from the demodulated signal and supplies it to the energy despreading unit 203.

  As described above, the energy despreading unit 203 is supplied with a pilot signal symbol and a synchronization pulse from the synchronization unit 202 and also recognizes from the error correction decoding unit 205 based on the TMCC signal obtained from the demodulated signal. A selection signal representing a modulation scheme (selective modulation scheme) of symbols of the main signal and the pilot signal can be supplied.

  The energy despreading unit 203 performs energy despreading synchronized with the synchronization pulse from the synchronization unit 202 on the pilot signal symbol from the synchronization unit 202 based on the selection modulation method represented by the selection information from the error correction decoding unit 205. Processing is performed, and the symbol of the pilot signal after energy despreading is supplied to the nonlinear distortion calculation unit 204.

  The nonlinear distortion calculation unit 204 uses the pilot signal symbol from the energy despreading unit 203 to generate a pilot signal in the modulation signal on the transmission path between the transmission device 11 and the reception device 12, and consequently, a symbol of the main signal. Nonlinear distortion is calculated, and the calculation result is supplied to the error correction decoding unit 205.

  The error correction decoding unit 205 performs energy despreading processing on the demodulated signal supplied from the synchronization unit 202. Further, error correction decoding section 205 decodes the TMCC signal from the demodulated signal after energy despreading, and recognizes the modulation scheme (selected modulation scheme) of the main signal and the pilot signal based on the TMCC signal. . Then, the error correction decoding unit 205 supplies a selection signal representing the selection modulation scheme to the energy despreading unit 203.

  Further, the error correction decoding unit 205 uses the non-linear distortion calculation result from the non-linear distortion calculation unit 204 to compensate for non-linear distortion occurring in the symbol of the main signal in the demodulated signal after energy despreading, and The main signal is error-corrected by performing maximum likelihood decoding of the main signal symbol after compensation of the nonlinear distortion, and then output.

  In the reception device 12 configured as described above, the orthogonal demodulation unit 201 performs orthogonal demodulation of the modulation signal from the transmission device 11 and supplies the demodulated signal obtained as a result to the synchronization unit 202.

  The synchronization unit 202 establishes synchronization based on the symbol of the synchronization signal in the demodulated signal from the quadrature demodulation unit 201, supplies the synchronized demodulated signal to the error correction decoding unit 205, and converts the synchronization pulse to the energy inverted signal. This is supplied to the diffusion unit 203. The synchronization unit 202 also extracts a pilot signal symbol from the demodulated signal and supplies it to the energy despreading unit 203.

  The error correction decoding unit 205 decodes the TMCC signal from the demodulated signal from the synchronization unit 202, recognizes the modulation scheme (selective modulation scheme) of the main signal and pilot signal symbols based on the TMCC signal, A selection signal representing the selective modulation method is supplied to the energy despreading unit 203.

  The energy despreading unit 203 performs energy despreading synchronized with the synchronization pulse from the synchronization unit 202 on the pilot signal symbol from the synchronization unit 202 based on the selection modulation method represented by the selection information from the error correction decoding unit 205. Processing is performed, and the symbol of the pilot signal after energy despreading is supplied to the nonlinear distortion calculation unit 204.

  The nonlinear distortion calculation unit 204 calculates the nonlinear distortion generated in the main signal symbol using the pilot signal symbol from the energy despreading unit 203, and supplies the calculation result to the error correction decoding unit 205.

  The error correction decoding unit 205 uses the nonlinear distortion calculation result from the nonlinear distortion calculation unit 204 to compensate for nonlinear distortion occurring in the symbol of the main signal in the demodulated signal, and further compensates for the nonlinear distortion after compensation. By performing maximum likelihood decoding of the symbol of the signal, etc., error correction of the main signal is performed and output.

  For example, image data and audio data as main signals output from the error correction decoding unit 205 are supplied to a display or a speaker (not shown), and a corresponding image is displayed, and corresponding audio is output.

  Next, FIG. 7 is a block diagram illustrating a configuration example of the energy despreading unit 203 in FIG.

  The energy despreading unit 203 includes a spreading code generation unit 261, an initial value output unit 262, an initial value setting unit 263, a level conversion unit 264, and a spreading unit 265, and is supplied from the synchronization unit 202 (FIG. 6). An energy despreading process is performed on the signal symbols.

  That is, the spread code generation unit 261, the initial value output unit 262, the initial value setting unit 263, the level conversion unit 264, and the spread unit 265 are the spread code generation unit 61 and the initial value output unit 62 in the energy spread unit 42 of FIG. , The initial value setting unit 63, the level conversion unit 64, and the spreading unit 65 are configured in the same manner. The energy spreading unit 42 in FIG. 4 applies the pilot signal symbols supplied from the synchronization unit 202 (FIG. 6). An energy reverse diffusion process similar to the energy diffusion process to be performed is performed.

Accordingly, in the energy despreading unit 203 in FIG. 7, the spreading code generation unit 261 is expressed as an irreducible polynomial X ¹⁵ + X ¹⁴ +1 as a spreading code in the same manner as the spreading code generation unit 61 in FIG. A 15th order M-sequence is generated and supplied to the level converter 264.

  The level conversion unit 264 performs level conversion of the spreading code (bits) supplied from the spreading code generation unit 261 and supplies the level to the spreading unit 265.

  The spreading unit 265 is supplied with a spreading code from the level converting unit 264 and also has an I component (a symbol of a pilot signal that has been subjected to energy spreading by the transmission device 11) from the synchronizing unit 202 (FIG. 6). I ′) and Q component (Q ′) are supplied.

  Spreading section 265 applies the level-converted spreading code from level converting section 264 to the symbol I component (I ′) and Q component (Q ′) of the pilot signal supplied from synchronizing section 202 (FIG. 6). By multiplying, the symbols of the pilot signal are despread. Then, spreading section 265 supplies the I component and Q component of the pilot signal symbol after energy despreading to nonlinear distortion calculation section 204 (FIG. 6).

  On the other hand, the initial value output unit 262 is associated with each of BPSK, QPSK, 8PSK, 16APSK, and 32APSK in the same way as the initial value output unit 62 of FIG. Is remembered.

  The initial value output unit 262 is supplied with selection information from the error correction decoding unit 205 (FIG. 6). The initial value output unit 262 receives the selection information from the error correction decoding unit 205 (FIG. 6). The initial value associated with the selected modulation scheme represented by the selection information, that is, the modulation scheme obtained by digitally modulating the symbols of the main signal and pilot signal in the modulated signal is selected and output to spreading code generating section 261.

  The initial value setting unit 263 is supplied with a synchronization pulse from the synchronization unit 202. The initial value setting unit 263 resets the count value in synchronization with the synchronization pulse of the synchronization unit 202, and sends an initialization signal to the spreading code generation unit 261 in the same manner as the initial value setting unit 263 of FIG. By outputting, the initial value output from the initial value output unit 262 at the beginning of the frame or slot is set to the initial value of the M sequence generated by the spreading code generation unit 261.

  The initial value output unit 262 is given a command from the outside, and the initial value output unit 262 stores the BPSK, QPSK, 8PSK, 16APSK as in the case of the initial value output unit 62 of FIG. , And 32APSK, the initial value of the spreading code associated with each can be rewritten. A command from the outside to the initial value output unit 262 can be given from, for example, a control microcomputer (not shown) that controls the receiving device 12.

  That is, for example, the transmission device 11 transmits an upgraded version of the control software for the reception device 12, and the reception device 12 downloads the upgraded version of the control software. In the receiving device 12, the control microcomputer can execute the upgraded version of the control software to rewrite the initial value of the spread code stored in the initial value output unit 262.

  As described above, the transmission apparatus 11 is a modulated signal obtained by digitally modulating a symbol of a frame composed of 120 slots including at least one main signal symbol and pilot signal symbol. The modulation obtained by digitally modulating the main signal symbol and the pilot signal symbol with a selective modulation method selected from the five modulation methods BPSK, QPSK, 8PSK, 16APSK, and 32APSK. A signal is transmitted.

  Then, in the energy spreading of the pilot signal symbol, which is performed when the modulated signal is transmitted in the transmission device 11, among the initial values of the spreading codes associated with BPSK, QPSK, 8PSK, 16APSK, and 32APSK, An initial value associated with the selected modulation scheme is selected, and a spreading code used for energy spreading is generated using the initial value.

  Therefore, when digital modulation is performed with BPSK, QPSK, 8PSK, 16APSK, or 32APSK, an appropriate value can be used as the initial value of the spreading code used for the energy spreading of the symbols of the pilot signal. In the device 12, appropriate processing can be performed using the pilot signal.

  That is, for each of the BPSK, QPSK, 8PSK, 16APSK, and 32APSK modulation schemes, for example, the initial value of the spreading code that increases (including the maximum) the PAPR of the modulation signal of the pilot signal symbol after energy spreading is used. By storing in association with each other, even if any of BPSK, QPSK, 8PSK, 16APSK, and 32APSK is selected as the selective modulation method, the PAPR of the pilot signal (symbol modulation signal) is changed. Can be great.

  As a result, in the receiving apparatus 12, the non-linear distortion generated on the transmission path for the main signal due to the pilot signal having such a large PAPR is appropriate even if the PAPR of the main signal (symbol modulation signal) is large. Can be compensated for.

  In addition, for each of the BPSK, QPSK, 8PSK, 16APSK, and 32APSK modulation schemes, for example, an initial value of a spreading code that uniformly appears a symbol value that can be taken by a symbol of a pilot signal after energy spreading is associated and stored. By this, even if any of BPSK, QPSK, 8PSK, 16APSK, and 32APSK is selected as the selective modulation scheme, for each of the symbol values that can be taken by the pilot signal symbol of the selective modulation scheme, It is possible to determine nonlinear distortion that occurs on the transmission path.

  As a result, the receiving apparatus 12 can appropriately compensate for the nonlinear distortion occurring on the transmission path for the main signal symbol digitally modulated by the selective modulation method, regardless of the symbol value.

  For the BPSK, QPSK, 8PSK, 16APSK, and 32APSK modulation schemes as described above, the initial value of the spreading code that increases the PAPR of the modulation signal of the pilot signal symbol after energy spreading, and after energy spreading The initial value of the spread code that causes the symbol values that can be taken by the symbols of the pilot signal to uniformly appear can be obtained by simulation, for example.

  Here, hereinafter, a simulation for obtaining an initial value at which the PAPR becomes large or an initial value at which the symbol values appear uniformly is referred to as an initial value calculation simulation.

  Hereinafter, the results of the initial value calculation simulation performed by the present inventors will be described with reference to FIGS.

  FIG. 8 shows the arrangement of 32 signal points of 32APSK employed in the initial value calculation simulation on the IQ plane.

  In FIG. 8, a black circle (● mark) filled with black represents a signal point, and a number near the signal point represents a symbol value assigned to the signal point in decimal. Yes.

  Assuming that a signal point is represented as a signal point #n by using a decimal number n located in the vicinity of the signal point, in the transmission device 11, a symbol having a symbol value of decimal number n is represented by Maps to signal point #n. Therefore, for example, a symbol whose symbol value is 01011b (= 11) in binary is mapped to signal point # 11.

  FIG. 9 shows signal points representing pilot signal symbols before and after energy diffusion when 32APSK is used as the selective modulation method.

That is, in the initial value calculation simulation, a 15th order M sequence as a spreading code is generated for each of 2 ¹⁵ kinds of initial values that can be taken as initial values of the 15th order M sequence, and BPSK, For each of the QPSK, 8PSK, 16APSK, and 32APSK modulation schemes, the symbol mapped to each signal point of the modulation scheme is subjected to energy spreading using a spreading code to obtain the signal point of the symbol after energy spreading. It was.

  Furthermore, in the initial value calculation simulation, modulation is performed when a filter that performs oversampling twice the symbol rate and has a roll-off rate of 0.20 as the transmission rate of the symbol rate is used as the transmission filter 44 (FIG. 3) of the transmission device 11. The PAPR of the signal was obtained.

  FIG. 9 shows 32 signal points of 32APSK and signal points after energy spreading of symbols mapped to the 32 signal points.

  That is, the upper part of FIG. 9 shows signal points when the PAPR of the modulated signal is minimized, and the lower part of FIG. 9 shows signal points when the PAPR of the modulated signal is maximized.

  In the initial value calculation simulation, when the initial value of the M sequence is 4963 decimal, the PAPR of the modulation signal is minimized (upper part of FIG. 9), and the initial value of the M sequence is 5662 decimal. In some cases, the PAPR of the modulation signal became maximum (FIG. 9 bottom).

  In FIG. 9, “transmission symbol number” represents 32 symbols p0 to p31 of 32APSK arranged in one slot to be subjected to energy spreading, and “pre-spreading signal point” represents symbol p # m (m = 0, 1,..., 31) represent mapped 32APSK signal points. Further, “spreading code” represents (the value of) the spreading code used for energy diffusion of the symbol p # m, and “spread signal point” represents the signal point of the symbol after energy diffusion of the symbol p # m. To express.

  According to each of the upper part of FIG. 9 and the lower part of FIG. 9, energy diffusion causes a transition (signal point transition) from a signal point of one symbol p # m to a signal point of the next symbol p # m + 1. By comparing FIG. 9 and the bottom of FIG. 9, it can be seen that the signal point transition is different if the initial value of the M sequence as the spreading code is different.

  Signal point transition that passes through the vicinity of the origin of the IQ plane after energy diffusion, in particular, the signal point that the signal point on the outermost periphery passes through the vicinity of the origin of the IQ plane in the arrangement of the signal points in FIG. When a transition occurs, overshoot occurs in the processing of the transmission filter 44. Due to the overshoot, the peak power of the modulation signal becomes large, and consequently, the PAPR also becomes large.

  In addition, when the spreading codes used for energy diffusion of the symbols of two signal points that are symmetrical with respect to the origin of the IQ plane do not match, for example, on one side of the two signal points, The signal point of the symbol after energy spreading is biased, and a symbol value that does not appear among the 32 symbol values that can be taken by the 32APSK symbol after energy spreading occurs.

  Then, according to FIG. 9, if the initial value of the M sequence as the spreading code is different, the symbol value that does not appear among the 32 symbol values that can be taken by the 32APSK symbol after energy spreading (“post-spread signal point”). ”) And the number of symbol values (“ post-spread signal points ”) that appear among the 32 symbol values that can be taken by the 32APSK symbols after energy diffusion (hereinafter referred to as the number of transmission signal points as appropriate). Is different.

  FIG. 10 shows a Gaussian plane (IQ plane) (IQ constellation) in which the output of the transmission filter 44 (FIG. 3) is plotted when 32APSK is the selective modulation method.

  Note that FIG. 10 shows the output of the transmission filter 44 when the initial value of the M sequence is 4963 decimal and the PAPR of the modulated signal is minimized (upper part of FIG. 9). Further, the lower part of FIG. 10 shows the output of the transmission filter 44 when the initial value of the M sequence is set to 5562 in decimal and the PAPR of the modulation signal is maximized (lower part of FIG. 9).

  In FIG. 9 where PAPR is minimum, “spread signal points” when “send symbol numbers” are p10, p11, and p12 are signal points # 10, # 11, and # 10, respectively. The signal point transition is a transition between signal points # 10 and # 11 existing adjacent to each other in the same quadrant as shown in FIG.

  On the other hand, in the lower part of FIG. 9 when the PAPR is maximum, the “spread signal points” when the “transmission symbol numbers” are p10, p11, and p12 are signal points # 12, # 11, and # 10, respectively. As shown in the lower part of FIG. 10, there is a signal point transition across the I axis from signal point # 12 to signal point # 11. As a result, overshoot occurs at the next signal point transition from signal point # 11 to signal point # 10, and the PAPR of the modulation signal becomes large.

11, as a selection modulation method 32APSK, PAPR for the pilot signal subjected to energy spread in the generated spreading code with the (initial value of the total 2 ¹⁵ kinds of 15-bit M sequence) initial values, and sends The number of signal points is shown.

  That is, FIG. 11 shows the relationship between the initial value of the spread code and the PAPR for the pilot signal when the initial value is adopted. Also, the lower part of FIG. 11 shows the relationship between the initial value of the spreading code and the number of transmission signal points for the pilot signal when the initial value is adopted.

12, as the selected modulation scheme 16APSK, PAPR for the pilot signal subjected to energy spread in the generated spreading code with the (initial value of the total 2 ¹⁵ kinds of 15-bit M sequence) initial values, and sends The number of signal points is shown.

  That is, FIG. 12 shows the relationship between the initial value of the spreading code and the PAPR for the pilot signal when the initial value is adopted. The lower part of FIG. 12 shows the relationship between the initial value of the spreading code and the number of transmission signal points for the pilot signal when the initial value is adopted.

  According to FIG. 11 or FIG. 12, it can be seen that the PAPR and the number of transmission signal points both depend on the initial value (depending on the initial value). 11 and 12, it can be seen that the PAPR and the number of transmission signal points depend on the modulation method.

  Therefore, in the transmission apparatus 11, by associating the initial value of the spreading code with each of BPSK, QPSK, 8PSK, 16APSK, and 32APSK, each of BPSK, QPSK, 8PSK, 16APSK, and 32APSK is a selective modulation scheme. When selected, it is possible to increase the PAPR of the pilot signal digitally modulated by the selected modulation method, to increase the number of transmission signal points (to make the symbol values that symbols can take appear uniformly), etc. It becomes possible.

  That is, in the initial value calculation simulation, an initial value that maximizes the PAPR is obtained for each of the BPSK, QPSK, 8PSK, 16APSK, and 32APSK modulation schemes, and stored in the transmission device 11 and the reception device 12. it can. In the initial value calculation simulation, an initial value that maximizes the number of transmission signal points is obtained for each of the BPSK, QPSK, 8PSK, 16APSK, and 32APSK modulation schemes, and stored in the transmission device 11 and the reception device 12. it can.

  In addition, in the initial value calculation simulation, for each of the BPSK, QPSK, 8PSK, 16APSK, and 32APSK modulation schemes, an initial value for increasing the PAPR and increasing the number of transmission signal points (symbols) Can be obtained and stored in the transmission device 11 and the reception device 12.

  In the initial value calculation simulation, 0 is excluded from the target of the initial value of the spreading code. When 0 is adopted as the initial value of the spreading code, the number of transmission signal points is maximized, but the spreading code with the initial value of 0 simply leaves the target symbol of energy spreading (energy despreading) as it is, This is because it does not function as a spreading code.

  Here, the initial value for increasing the PAPR and the initial value for increasing the number of transmission signal points is the initial value for maximizing the PAPR and the maximum number of transmission signal points. If an initial value exists, the initial value is optimal. However, if there is no such initial value, it is necessary to set the PAPR and the number of transmission signal points as needed from among the initial values that increase the PAPR and increase the number of transmission signal points. It is desirable to adopt an initial value that is balanced.

  When the PAPR is large, the frequency band of the modulation signal is expanded by the non-linear distortion caused by the amplification of the modulation signal by the non-linear amplifier performed in the orthogonal modulation unit 45 of the transmission device 11 (FIG. 3), and the frequency Band usage efficiency may be degraded.

  In addition, the nonlinear distortion generated in the modulation signal becomes a problem when, for example, an amplitude variable modulation method in which the amplitude of the modulation signal is not constant, such as APSK or QAM (Quadrature Amplitude Modulation), is selected as the selective modulation method. . On the other hand, for example, when a constant amplitude modulation method in which the amplitude of the modulation signal is constant, such as BPSK or QPSK, is selected as the selective modulation method, nonlinear distortion generated in the modulation signal is rarely a problem.

  Therefore, when the plurality of modulation schemes that can be selected as the selective modulation scheme (hereinafter, referred to as a plurality of modulation schemes to be selected as appropriate) is only the variable amplitude modulation scheme, PAPR is further set as the initial value of the spread code. An initial value to be increased (or an initial value to increase PAPR and an initial value to increase the number of transmission signals) can be adopted.

  In addition, when a plurality of modulation schemes to be selected are only constant amplitude modulation schemes, the initial value for spreading code is an initial value for making PAPR smaller (or an initial value for making PAPR smaller). And an initial value for increasing the number of transmission signal points).

  Furthermore, when a variable amplitude modulation method and a constant amplitude modulation method are mixed among a plurality of modulation methods to be selected, the initial value (or PAPR) for increasing the PAPR is set for the variable amplitude modulation method. Can be used as an initial value for increasing the number of transmission signal points. For the constant amplitude modulation method, an initial value that makes PAPR smaller (or an initial value that makes PAPR smaller and also increases the number of transmission signal points) may be adopted. it can.

  FIG. 13 shows initial values obtained by an initial value calculation simulation performed by the present inventors.

  That is, in FIG. 13, initial values obtained for each of BPSK, QPSK, 8PSK, 16APSK, and 32APSK that make PAPR larger and initial values that make the number of transmission signal points larger are shown. Value set # 1 is shown.

  Further, the lower part of FIG. 13 shows initial values for making the PAPR smaller, obtained for each of BPSK, QPSK, and 8PSK, which are constant amplitude modulation methods among BPSK, QPSK, 8PSK, 16APSK, and 32APSK. And an initial value for increasing the number of transmission signal points, and an initial value for increasing the PAPR obtained for each of 16APSK and 32APSK which are variable amplitude modulation systems, and the number of transmission signal points An initial value set # 2 with an initial value to be larger is shown.

  In FIG. 13, the initial value for increasing the PAPR and the initial value for increasing the number of transmission signal points are 000011111000000b for BPSK, 110100111100101b for QPSK, and 8PSK. For example, 010000110100111b is obtained, for 16APSK, 010011110000110b is obtained, and for 32APSK, 001111010101010b is obtained.

  In the lower part of FIG. 13, for BPSK, QPSK, and 8PSK which are constant amplitude modulation systems, initial values that make PAPR smaller and initial values that make the number of transmission signal points larger are as follows. Thus, 011010101101101b, 010000100001000b for QPSK, and 010110011011011b for 8PSK, respectively, are obtained and are initial values that make PAPR larger for 16APSK and 32APSK which are variable amplitude modulation schemes. In addition, 010011110000110b is obtained for 16APSK and 001111010101010b is obtained for 32APSK as initial values for increasing the number of transmission signal points.

  Note that the initial values shown in FIG. 13 are values based on the signal point arrangement of BPSK, QPSK, 8PSK, 16APSK, and 32APSK shown in FIG. In this case, it is necessary to perform the initial value calculation simulation again to obtain the initial value again.

  Here, even when the arrangement of signal points is changed, the initial value can be obtained again by the initial value calculation simulation. In this case, in the transmission device 11 (FIG. 3), an instruction is sent from the control microcomputer of the transmission device 11 to the initial value output unit 62 (FIG. 4), whereby the initial value output unit 62 (initial value storage unit 110) Can be rewritten to the initial value obtained again by the initial value calculation simulation. Further, the receiving device 12 (FIG. 6) downloads the upgraded version of the control software from the transmitting device 11, causes the control microcomputer of the receiving device 12 to execute the upgraded version of the control software, and sets the initial value. The stored content of the output unit 262 (FIG. 7) can be rewritten with the initial value obtained again by the initial value calculation simulation.

  In this embodiment, a 15th-order M sequence is used as a PRBS as a spreading code, but the spreading code is not limited to a 15th-order M sequence.

  Also, the format of the modulation signal is not limited to the format of FIG.

  Further, the plurality of modulation schemes are not limited to the five modulation schemes of BPSK, QPSK, 8PSK, 16APSK, and 32APSK, and may be four or less (and two or more) or six. It may be above.

  As the plurality of modulation schemes, for example, a multi-level modulation scheme such as QAM other than BPSK, QPSK, 8PSK, 16APSK, and 32APSK can be employed.

  In the above, the case where the present invention is applied to digital broadcasting has been described. However, the present invention can also be applied to digital communication for transmitting a modulation signal obtained by performing digital modulation.

  The embodiment of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present invention.

It is a figure which shows the structural example of one Embodiment of the broadcast system to which this invention is applied. It is a figure which shows the format of a modulation signal. 3 is a block diagram illustrating a configuration example of a transmission device 11. FIG. 3 is a block diagram illustrating a configuration example of an energy diffusion unit 42. FIG. It is a flowchart explaining the process of energy spreading | diffusion. 3 is a block diagram illustrating a configuration example of a receiving device 12. FIG. 3 is a block diagram illustrating a configuration example of an energy despreading unit 203. FIG. It is a figure which shows arrangement | positioning of the signal point of 32APSK. It is a figure which shows the initial value of the spreading code with which PAPR of the modulation signal of 32APSK becomes the minimum, and the initial value of the spreading code with which PAPR becomes the maximum. It is a figure which shows the constellation of the modulation signal from which PAPR becomes the minimum, and the constellation of the modulation signal from which PAPR becomes the maximum. It is a figure which shows PAPR of the modulation signal of 32APSK with respect to each initial value of a spreading code, and the number of the appearing signal points (number of transmission signal points). It is a figure which shows PAPR of the modulation signal of 16APSK with respect to each initial value of a spreading code, and the number of the appearing signal points. It is a figure which shows the initial value of the spreading code calculated | required by the initial value calculation simulation. It is a figure which shows the example of arrangement | positioning of a signal point.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Transmitter, 12 Receiver, 31 Synchronization signal output part, 32 TMCC output part, 33 Main signal output part, 34 Pilot signal output part, 35 Modulation system selection part, 36 thru | or 39 Mapping part, 40 thru | or 42 Energy spreading part, 43 multiplexing unit, 44 transmission filter, 45 orthogonal modulation unit, 61 spreading code generation unit, 62 initial value output unit, 63 initial value setting unit, 64 level conversion unit, 65 spreading unit, 101 ₁ to ₁₀ 115 selector, 102 ₁ Or 102 ₁₅ latch circuit, 103 EXOR gate, 110 initial value storage unit, 111 BPSK initial value storage unit, 112 QPSK initial value storage unit, 1 1 8PSK initial value storage unit, 114 16APSK initial value storage unit, 115 32APSK Initial value storage unit, 116 selector, 117 stored value setting unit, 121 counter, 131, 132 operation unit, 201 Demodulation unit, 202 synchronization unit, 203 energy despreading unit, 204 nonlinear distortion calculation unit, 205 error correction decoding unit, 261 spreading code generation unit, 262 initial value output unit, 263 initial value setting unit, 264 level conversion unit, 265 spreading Part

Claims (12)

In a transmission device that transmits a modulated signal obtained by performing digital modulation,
A symbol of a frame composed of a plurality of slots including at least one slot including a symbol of a main signal that is information to be transmitted and a symbol of a pilot signal used to compensate nonlinear distortion occurring on the transmission path on the receiving side A modulation signal obtained by digitally modulating the symbol of the main signal and the symbol of the pilot signal by digital modulation using a selected modulation method selected from a plurality of modulation methods A transmission device for transmitting a signal;
In association with each of the plurality of modulation schemes, storage means for storing an initial value of PRBS (Pseudorandom Binary Sequence) as a spreading code used for energy spreading;
Selecting means for selecting an initial value associated with the selected modulation scheme from among initial values associated with a plurality of modulation schemes stored in the storage means;
Generating means for generating the spreading code using the initial value;
A transmission apparatus comprising: spreading means for spreading energy of symbols of the pilot signal using the spreading code. The initial value associated with the modulation scheme is a value that maximizes or minimizes the PAPR (Peak-to-Average Power Ratio) of the modulation signal of the symbol obtained by energy spreading the symbol of the pilot signal of the modulation scheme The transmission device according to claim 1. The transmission apparatus according to claim 2, wherein an initial value that maximizes or minimizes the PAPR of the modulated signal is obtained by simulation. The transmission apparatus according to claim 1, wherein the initial value associated with the modulation scheme is a value that uniformly causes a symbol value that can be taken by a symbol obtained by energy-spreading a symbol of the pilot signal of the modulation scheme. The transmission device according to claim 4, wherein an initial value for causing the symbol values to appear uniformly is obtained by simulation. The transmission apparatus according to claim 1, further comprising initial value setting means for setting the initial value in the generating means in one frame period or one slot period. The transmission apparatus according to claim 1, further comprising: a stored value setting unit that rewrites the initial value stored in the storage unit by setting an initial value in the storage unit. The initial value associated with the modulation scheme is greater or lesser the PAPR (Peak-to-Average Power Ratio) of the modulation signal of the symbol obtained by energy spreading the symbol of the pilot signal of the modulation scheme, The transmitting apparatus according to claim 1, wherein a symbol value that can be taken by a symbol obtained by energy-spreading a symbol of the pilot signal of the modulation scheme appears more uniformly. The initial value associated with the modulation scheme is
Of the plurality of modulation schemes, for a constant amplitude modulation scheme in which the amplitude of the modulation signal is constant, PAPR (Peak) of the modulation signal of the symbol obtained by energy spreading the symbols of the pilot signal of the constant amplitude modulation scheme -to-Average Power Ratio), and a symbol value that can be taken more uniformly by a symbol obtained by energy-spreading the symbol of the pilot signal of the modulation scheme.
Of the plurality of modulation schemes, for the variable amplitude modulation scheme where the amplitude of the modulation signal is not constant, the PAPR of the modulation signal of the symbol obtained by energy spreading the symbol of the pilot signal of the variable amplitude modulation scheme is obtained. The transmission apparatus according to claim 1, wherein the transmission value is a value that makes a symbol value that can be taken larger and that a symbol obtained by energy-spreading a symbol of the pilot signal of the variable amplitude modulation scheme appear more uniformly. The generating means generates a 15th order M-sequence (maximal-length sequences) as the spreading code,
The plurality of modulation schemes include two or more of BPSK (Binary Phase Shift Keying), QPSK (Quadrature Phase Shift Keying), 8PSK (Phase Shift Keying), 16APSK (Amplitude Phase Shift Keying), and 32APSK,
The initial value associated with BPSK is 00001111000000b (indicating that the previous value is a binary number)
The initial value associated with QPSK is 110100111100101b,
The initial value associated with 8PSK is 010000110100111b,
The initial value associated with 16APSK is 010011110000110b,
The transmission apparatus according to claim 1, wherein an initial value associated with 32APSK is 001111010101010b. The generating means generates a 15th order M-sequence (maximal-length sequences) as the spreading code,
The plurality of modulation schemes include two or more of BPSK (Binary Phase Shift Keying), QPSK (Quadrature Phase Shift Keying), 8PSK (Phase Shift Keying), 16APSK (Amplitude Phase Shift Keying), and 32APSK,
The initial value associated with BPSK is 011010101101101b (representing that the previous value is a binary number),
The initial value associated with QPSK is 010000100001000b,
The initial value associated with 8PSK is 010110011011011b,
The initial value associated with 16APSK is 010011110000110b,
The transmission apparatus according to claim 1, wherein an initial value associated with 32APSK is 001111010101010b. In a transmission method of a transmission apparatus that transmits a modulation signal obtained by performing digital modulation,
A symbol of a frame composed of a plurality of slots including at least one slot including a symbol of a main signal that is information to be transmitted and a symbol of a pilot signal used to compensate nonlinear distortion occurring on the transmission path on the receiving side A modulation signal obtained by digitally modulating the symbol of the main signal and the symbol of the pilot signal by digital modulation using a selected modulation method selected from a plurality of modulation methods A transmission method of a transmission device that transmits a signal,
Corresponding to the selected modulation method from among the initial values associated with the plurality of modulation methods stored in the storage means for storing the initial value of the spreading code used for energy spreading in association with each of the plurality of modulation methods Select the default value attached,
Using the initial value to generate the spreading code;
A transmission method including a step of performing energy spreading of symbols of the pilot signal using the spreading code.

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