Transmitting device, control circuit, storage medium, and transmitting method

Abstract

The present invention obtains a transmitting device (1) capable of improving required reception power while suppressing an increase in an envelope fluctuation amount when a PSK modulation scheme in which a reference phase is shifted by a prescribed phase for each symbol timing is applied. The transmitting device (1) comprises: a mapping rule generating unit (10) that generates a mapping rule whereby an increase in an envelope fluctuation amount is suppressed; a symbol mapping unit (11) that performs symbol mapping with respect to an input information bit sequence on the basis of the mapping rule to generate a mapping symbol sequence; and a modulating unit (12) that generates a modulated signal with respect to the mapping symbol sequence using a Phase Shift Keying modulation scheme in which a reference phase is shifted by a prescribed phase for each symbol timing.

Description

Transmitting device, control circuit, storage medium, and transmitting method

[0001] The present disclosure relates to a transmitting device, a control circuit, a storage medium, and a transmitting method that perform symbol mapping.

[0002] Conventionally, as compared with the PSK (Phase Shift Keying) method, which is one of the modulation methods, methods that have a smaller amount of envelope fluctuation and can improve power efficiency include the π / 4 shift QPSK (Quadrature PSK) method, which shifts a reference phase by π / 4 or π / 2 for each symbol timing, and the π / 2 shift BPSK (Binary PSK) method (Non-Patent Document 1).

[0003] Yoshihiko Akaiwa, and Yoshinori Nagata, "Highly Efficient Digital Mobile Communications with a Linear Modulation Method" IEEE Journal on Selected Areas in Communications, Vol.SAC-5, No.5, June 1987.

[0004] However, the π / 4 shift QPSK system, π / 2 shift BPSK system, etc. have a problem that the effect of improving power efficiency is small compared to the FSK (Frequency Shift Keying) system, which also has a small envelope fluctuation, because the envelope fluctuation is large. Furthermore, the π / 4 shift QPSK system, π / 2 shift BPSK system, etc. have a higher transmission rate than the FSK system, but on the other hand, have a problem that the required reception power is lower.

[0005] The present disclosure has been made in consideration of the above, and aims to provide a transmitting device that can improve required received power while suppressing an increase in envelope fluctuation when a PSK modulation method is applied, in which a reference phase is shifted by a specified phase at each symbol timing.

[0006] In order to solve the above-mentioned problems and achieve the object, a transmitting device of the present disclosure is characterized by comprising: a mapping rule generating unit that generates a mapping rule that suppresses an increase in the amount of envelope fluctuation; a symbol mapping unit that performs symbol mapping on an input information bit sequence based on the mapping rule to generate a mapping symbol sequence; and a modulation unit that generates a modulated signal for the mapping symbol sequence using a Phase Shift Keying modulation method that shifts a reference phase by a specified phase for each symbol timing.

[0007] The transmitting device of the present disclosure has the advantage that, when a PSK modulation method is applied in which a reference phase is shifted by a specified phase at each symbol timing, it is possible to improve the required received power while suppressing an increase in envelope fluctuation.

[0008] FIG. 1 shows a configuration example of a transmitting device according to embodiment 1. Flowchart showing the operation of the transmitting device according to embodiment 1. FIG. 2 shows an example of a signal point arrangement in the π / 4 shift QPSK method used in the modulation section of the transmitting device according to embodiment 1. FIG. 3 shows an example of a mapping rule generated by the mapping rule generation section in the transmitting device according to embodiment 1 when the modulation method is the π / 4 shift QPSK method, the number of mapping symbols is 4, and the leading symbol is fixed. In the transmitting device according to embodiment 1,1 shows an example of signal point transition of a modulated signal modulated by a modulation unit for a mapping symbol sequence generated by a symbol mapping unit when "01" is 01. FIG. 2 shows an example of a mapping rule when the number of mapping symbols generated by a mapping rule generation unit of a transmitting device according to embodiment 1 is 2. FIG. 3 shows an example of a mapping rule when the number of mapping symbols generated by a mapping rule generation unit of a transmitting device according to embodiment 1 is 8. FIG. 4 shows an example of a mapping rule when the number of mapping symbols generated by a mapping rule generation unit of a transmitting device according to embodiment 1 is 4 and the leading symbol varies. FIG. 5 shows an example of a mapping rule when the modulation scheme applied in the modulation unit generated by the mapping rule generation unit of a transmitting device according to embodiment 1 is π / 2 shift BPSK and the number of mapping symbols is 2. 4 is a diagram showing an example of a mapping rule in the case of π / 4 shift QPSK modulation scheme of the transmitting device according to embodiment 1, the number of mapping symbols is 4, and the leading symbol is fixed. A diagram showing a mapping rule generated by a mapping rule generation unit of the transmitting device and a sequence of demodulated signals obtained by a receiving device when the modulation scheme of the transmitting device according to embodiment 1 is π / 4 shift QPSK modulation scheme, the number of mapping symbols is 4, and the leading symbol is fixed. A diagram showing an example of the configuration of a processing circuit when the processing circuit realizing the transmitting device according to embodiment 1 is configured with a processor and a memory. A diagram showing an example of the processing circuit when the processing circuit realizing the transmitting device according to embodiment 1 is configured with dedicated hardware. First diagram showing an example of the configuration of a transmitting device according to embodiment 2. First flowchart showing the operation of the transmitting device according to embodiment 2. First diagram showing a processing image in the transmitting device according to embodiment 2. Second diagram showing an example of the configuration of the transmitting device according to embodiment 2. Second flowchart showing the operation of the transmitting device according to embodiment 2. Second diagram showing a processing image in the transmitting device according to embodiment 2.

[0009] A transmitting device, a control circuit, a storage medium, and a transmitting method according to embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings.

[0010] First Embodiment Fig. 1 is a diagram showing an example of the configuration of a transmitting device 1 according to a first embodiment. The transmitting device 1 is a device that transmits a signal to a receiving device (not shown). As shown in Fig. 1, the transmitting device 1 includes a mapping rule generating unit 10, a symbol mapping unit 11, and a modulating unit 12. Fig. 2 is a flowchart showing the operation of the transmitting device 1 according to the first embodiment.

[0011] The mapping rule generator 10 generates a mapping rule that suppresses an increase in the amount of envelope fluctuation (step S1). The mapping rule generator 10 may generate a mapping rule that suppresses an increase in the amount of envelope fluctuation based on, for example, a modulation scheme used in the modulator 12 (described later), or may generate a mapping rule that suppresses an increase in the amount of envelope fluctuation for a specified number of mapping symbols. The mapping rule generator 10 may also generate a mapping rule that suppresses an increase in the amount of envelope fluctuation based on the presence or absence of known symbols used in timing synchronization or channel estimation in a receiving device (not shown), or may generate a mapping rule that determines the number of mapping symbols based on the propagation conditions of wireless communication and suppresses an increase in the amount of envelope fluctuation. The mapping rule generator 10 may determine the number of mapping symbols based on the modulation multi-level number in the modulator 12, whether the leading symbol is fixed, and the like, and generate a mapping rule that suppresses an increase in the amount of envelope fluctuation. The mapping rule generator 10 outputs the generated mapping rule to the symbol mapper 11.

[0012] The symbol mapping unit 11 acquires the mapping rule from the mapping rule generation unit 10. The symbol mapping unit 11 also accepts an external input of an information bit sequence. Based on the mapping rule acquired from the mapping rule generation unit 10, the symbol mapping unit 11 performs symbol mapping on the externally input information bit sequence to generate a mapping symbol sequence (step S2). The symbol mapping unit 11 outputs the generated mapping symbol sequence to the modulation unit 12.

[0013] The modulator 12 acquires the mapping symbol sequence from the symbol mapping unit 11. The modulator 12 generates a modulated signal using a π / 4 shift QPSK scheme, a π / 4 shift DQPSK (Differential QPSK) scheme, a π / 2 shift BPSK scheme, or the like for the mapping symbol sequence acquired from the symbol mapping unit 11. The modulator 12 generates a modulated signal for the mapping symbol sequence acquired from the symbol mapping unit 11 using a modulation scheme that alternately uses PSK schemes with a specified phase difference for each symbol, i.e., a PSK modulation scheme that shifts a reference phase by a specified phase for each symbol timing (step S3). The modulator 12 outputs the generated modulated signal.

[0014] Next, a detailed description will be given of the characteristic operation of the transmitting device 1 according to the present embodiment. Note that, here, an example will be described in which the modulation method is π / 4 shift QPSK, the number of mapping symbols is 4, and the first symbol is fixed, but the modulation method, the number of mapping symbols, whether the first symbol is fixed, etc. are not limited to these.

[0015] 3 is a diagram showing an example of a signal point arrangement in a π / 4-shift QPSK system used by the modulation unit 12 of the transmitting device 1 according to the first embodiment. In the example of FIG. 3, the modulation unit 12 generates, as a modulated signal, one of four signal points with phases of 0, 90, 180, and 270 degrees for odd-numbered symbols and four signal points with phases of 45, 135, 225, and 315 degrees for even-numbered symbols, depending on the information bit sequence. Note that the correspondence between each signal point and the information bit sequence is not limited to the example shown in FIG. 3. For example, the modulation unit 12 may use four signal points with phases of 45, 135, 225, and 315 degrees for odd-numbered symbols and four signal points with phases of 0, 90, 180, and 270 degrees for even-numbered symbols. Alternatively, the modulation unit 12 may use a signal point with a phase of 180 degrees for the odd-numbered symbols as the information bit sequence "00."

[0016] 4 is a diagram showing an example of a mapping rule generated by the mapping rule generation unit 10 in the case where the modulation scheme is π / 4 shift QPSK, the number of mapping symbols is 4, and the first symbol is fixed in the transmitting device 1 according to embodiment 1. When the mapping rule shown in FIG. 4 is used, for example, when the first symbol of the information bit string is "00", the second symbol is "01", and the third symbol is "01", the mapping symbol strings mapped by the symbol mapping unit 11 are "00, 00, 01, 01", "11, 10, 01, 11", and "00, 01, 10, 00", respectively. "00,00,01,01" is the output bit string corresponding to the input bit string "00" of odd symbols in FIG. 4(a), "11,10,01,11" is the output bit string corresponding to the input bit string "01" of even symbols in FIG. 4(b), and "00,01,10,00" is the output bit string corresponding to the input bit string "01" of odd symbols in FIG. 4(a).

[0017] 5A and 5B are diagrams showing an example of signal point transitions of a modulated signal obtained by modulating the mapping symbol sequence generated by the symbol mapping unit 11 in the modulation unit 12 when the information bit sequence is "00, 01, 01" in the transmitting device 1 according to embodiment 1. Note that FIG. 5A shows, as a comparative example, an example in which symbol mapping is not performed, i.e., symbol mapping is not applied. As shown in FIG. 5A, when symbol mapping is not applied and the information bit sequence "00, 01, 01" is modulated in accordance with the signal point constellation diagram shown in FIG. 3, the modulated signal transitions in the order of phase 0 → 135 → 90 degrees. At this time, the transition from the first symbol to the second symbol, i.e., the transition from phase 0 → 135 degrees, passes near the origin, resulting in an increased amount of envelope fluctuation.

[0018] On the other hand, when the mapping rule shown in Fig. 4 is applied to the transmitter 1, the symbol mapping unit 11 outputs "00, 00, 01, 01" for the first symbol "00" in the input information bit string, and therefore a modulated signal is generated that transitions between signal points of phase 0 → 45 → 90 → 135 degrees, as shown in Fig. 5(b-1). Note that the modulation unit 12 switches between the signal point constellations shown in Fig. 3 for each input bit string, regardless of the number of mapping symbols. Similarly, in the transmitting device 1, for the mapping symbol sequence "11, 10, 01, 11" output from the symbol mapping unit 11 for the second symbol "01" in the information bit sequence, the signal point undergoes a phase transition from 180 to 315 to 90 to 225 degrees as shown in FIG. 5(b-2), and for the mapping symbol sequence "00, 01, 10, 00" output from the symbol mapping unit 11 for the third symbol "01", the signal point undergoes a phase transition from 0 to 135 to 270 to 45 degrees as shown in FIG. 5(b-3).

[0019] From the above, it can be seen that in the transmitting device 1, by applying the mapping rule generated by the mapping rule generation unit 10 to generate a mapping symbol sequence in the symbol mapping unit 11, the amount of envelope fluctuation is suppressed and power efficiency is improved compared to the case without symbol mapping.

[0020] The mapping rule generated by the mapping rule generation unit 10 is not limited to the example shown in Fig. 4. The mapping rule generation unit 10 may change the mapping rule depending on the number of mapping symbols, the information bit string in which the leading symbol is input, etc., or may change the mapping rule depending on the modulation method applied by the modulation unit 12, such as the π / 4 shift DQPSK method or the π / 2 shift BPSK method. In either case, the mapping rule generation unit 10 generates a mapping rule that suppresses an increase in the amount of envelope fluctuation of the modulated signal generated by the modulation unit 12.

[0021] Fig. 6 is a diagram showing an example of mapping rules generated by the mapping rule generation unit 10 of the transmitting device 1 according to the first embodiment when the number of mapping symbols is 2. For example, when the number of mapping symbols is 2, the mapping rule generation unit 10 generates mapping rules for applying Fig. 6(a) to the 1st, 5th, 9th, ... symbols, applying Fig. 6(b) to the 2nd, 6th, 10th, ... symbols, applying Fig. 6(c) to the 3rd, 7th, 11th, ... symbols, and applying Fig. 6(d) to the 4th, 8th, 12th, ... symbols.

[0022] Fig. 7 is a diagram showing an example of a mapping rule generated by the mapping rule generation unit 10 of the transmitting device 1 according to the first embodiment when the number of mapping symbols is 8. For example, when the number of mapping symbols is 8, the mapping rule generation unit 10 may generate a mapping rule as shown in Fig. 7 regardless of the symbol number.

[0023] 8 is a diagram showing an example of a mapping rule in which the number of mapping symbols generated by the mapping rule generation unit 10 of the transmitting device 1 according to embodiment 1 is 4 and the leading symbol varies. For example, when the number of mapping symbols is 4, the mapping rule generation unit 10 may generate a mapping rule in which the leading symbol varies.

[0024] 9A and 9B are diagrams showing examples of mapping rules generated by the mapping rule generation unit 10 of the transmitting device 1 according to the first embodiment when the modulation scheme applied by the modulator 12 is the π / 2 shift BPSK scheme and the number of mapping symbols is two. Fig. 9A is a diagram showing an example of a signal point arrangement of a mapping symbol sequence in the π / 2 shift BPSK scheme. In the example of Fig. 9A, the mapping rule generation unit 10 generates the mapping rule for using Fig. 9B-1 for odd-numbered symbols and Fig. 9B-2 for even-numbered symbols when the modulation scheme applied by the modulator 12 is the π / 2 shift BPSK scheme.

[0025] Fig. 10 is a diagram showing an example of a mapping rule generated by the mapping rule generation unit 10 of the transmitting device 1 according to embodiment 1 when the modulation scheme applied by the modulation unit 12 is the π / 4 shift DQPSK scheme and the number of mapping symbols is 4. In the example of Fig. 10, when the modulation scheme applied by the modulation unit 12 is the π / 4 shift DQPSK scheme and the information bit sequence for the leading start symbol is "00", the mapping rule generation unit 10 generates a mapping rule for applying Fig. 10(a) to the first symbol corresponding to the start symbol, applying Fig. 10(b) to the second symbol, applying Fig. 10(c) to the third and subsequent odd-numbered symbols, and applying Fig. 10(d) to the third and subsequent even-numbered symbols.

[0026] 6 to 10 are mapping rules that suppress an increase in the amount of envelope fluctuation of the modulated signal generated by the modulator 12, thereby achieving the effect of improving power efficiency. In this embodiment, an example is shown in which the mapping rule generator 10 generates a mapping rule for each symbol of the information bit string. However, based on parameter information such as the number of mapping symbols and the modulation scheme, the mapping rule generator 10 may generate, for example, the two mapping rules shown in FIG. 4 and output them to the symbol mapper 11, and the symbol mapper 11 may select an appropriate mapping rule according to the symbol number of the input information bit string. Furthermore, the mapping rule generator 10 may adaptively generate a mapping rule based on information such as wireless propagation conditions transmitted from a control unit (not shown) included in the transmitter 1, for example, by generating a mapping rule that increases the number of mapping symbols when propagation conditions are poor.

[0027] In this way, the required reception power can be expected to be improved by combining the modulated signals generated by the transmitter 1 in units of the number of mapping symbols at the receiver side. For example, the receiver demodulates the timing-synchronized received signals using the same modulation method as the transmitter 1 to generate demodulated signals, and then performs combining processing based on the mapping rule in units of the number of mapping symbols.

[0028] 11 is a diagram showing the mapping rule generated by the mapping rule generator 10 of the transmitter 1 and a sequence of demodulated signals obtained by the receiver when the modulation scheme of the transmitter 1 according to the first embodiment is π / 4 shift QPSK, the number of mapping symbols is 4, and the first symbol is fixed. For example, when the demodulated signal of the first symbol is "00, 10, 01, 10," the receiver compares the demodulated signal of the first symbol with the mapping rule and finds that it is closest to the output bit when the input bit sequence is "10," and therefore generates "10" as the estimated bit sequence. Similarly, when the demodulated signal of the second symbol is "11, 01, 01, 00," the receiver compares the demodulated signal of the second symbol with the mapping rule and finds that it is closest to the output bit when the input bit sequence is "11," and therefore generates "11" as the estimated bit sequence.

[0029] When symbol mapping is not applied, two bits of the information bit sequence correspond to one symbol of the modulated signal and demodulated signal, whereas when the number of symbol mappings is set to four as exemplified in this embodiment, two bits of the information bit sequence correspond to four symbols of the modulated signal and demodulated signal. Therefore, when the number of symbol mappings is set to four, as shown in the first symbol in Fig. 11, even if an error occurs in one of the four symbols, the correct information bit sequence can be estimated, and the required received power can be improved by obtaining a combined gain.

[0030] 4, the beginning of each mapping symbol is set to a constant value regardless of the input bit string, so that the receiving device can treat the beginning of each mapping symbol as a known symbol. Therefore, by using this symbol, timing synchronization, transmission channel estimation, etc. can be realized without inserting a new known symbol.

[0031] Next, a description will be given of the hardware configuration of the transmitting device 1. In the transmitting device 1, the mapping rule generating unit 10, the symbol mapping unit 11, and the modulation unit 12 are realized by processing circuits. The processing circuit may be a processor and memory that executes a program stored in a memory, or may be dedicated hardware. The processing circuit is also called a control circuit.

[0032] FIG. 12 is a diagram illustrating an example of the configuration of a processing circuit 90 that implements the transmitting device 1 according to the first embodiment, where the processing circuit is configured with a processor 91 and a memory 92. The processing circuit 90 illustrated in FIG. 12 is a control circuit and includes a processor 91 and a memory 92. When the processing circuit 90 is configured with the processor 91 and the memory 92, each function of the processing circuit 90 is implemented by software, firmware, or a combination of software and firmware. The software or firmware is written as a program and stored in the memory 92. The processing circuit 90 implements each function by having the processor 91 read and execute the program stored in the memory 92. That is, the processing circuit 90 includes the memory 92 for storing a program that results in the processing of the transmitting device 1 being executed. This program can also be said to be a program that causes the transmitting device 1 to execute each function implemented by the processing circuit 90. This program may be provided by a storage medium on which the program is stored, or by other means such as a communication medium.

[0033] It can also be said that the above program causes the transmitting device 1 to execute the following steps: a mapping rule generation step in which the mapping rule generation unit 10 generates a mapping rule that suppresses an increase in the amount of envelope fluctuation; a symbol mapping step in which the symbol mapping unit 11 performs symbol mapping on the input information bit sequence based on the mapping rule to generate a mapping symbol sequence; and a modulation step in which the modulation unit 12 generates a modulated signal using a Phase Shift Keying modulation method that shifts a reference phase by a specified phase for each symbol timing for the mapping symbol sequence.

[0034] Here, the processor 91 is, for example, a CPU (Central Processing Unit), a processing device, an arithmetic unit, a microprocessor, a microcomputer, or a DSP (Digital Signal Processor), etc. The memory 92 is, for example, a non-volatile or volatile semiconductor memory such as a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory, an EPROM (Erasable Programmable ROM), or an EEPROM (Electrically EPROM), a magnetic disk, a flexible disk, an optical disk, a compact disk, a minidisk, or a DVD (Digital Versatile Disc).

[0035] FIG. 13 is a diagram illustrating an example of a processing circuit 93 that implements the transmitting device 1 according to the first embodiment and is configured with dedicated hardware. The processing circuit 93 illustrated in FIG. 13 may be, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or a combination thereof. The processing circuit may be partially implemented with dedicated hardware and partially implemented with software or firmware. In this way, the processing circuit can implement each of the above-described functions using dedicated hardware, software, firmware, or a combination thereof.

[0036] As described above, according to the present embodiment, the transmitter 1 generates and applies a mapping rule that can obtain a combined gain while suppressing an increase in envelope fluctuation, thereby achieving the effect of improving power efficiency and required received power. As a result, for example, by simply adding the mapping rule generator 10 and the symbol mapper 11 to an existing device that implements a π / 4 shift QPSK modulation scheme, power efficiency can be improved and an inexpensive amplifier can be applied. The transmitter 1 can improve the required received power while suppressing an increase in envelope fluctuation when applying a PSK modulation scheme that shifts a reference phase by a specified phase for each symbol timing, such as a π / 4 shift QPSK modulation scheme or a π / 2 shift BPSK modulation scheme.

[0037] Second Embodiment In a second embodiment, a transmitting device having a different configuration from the transmitting device 1 of the first embodiment will be described.

[0038] FIG. 14 is a first diagram showing a configuration example of a transmitting device 2 according to embodiment 2. The transmitting device 2 is obtained by adding a transmit diversity unit 13 and a symbol sorting unit 14 to the transmitting device 1 of embodiment 1 shown in FIG. 1. In the following description of this embodiment, only the differences from embodiment 1 will be described, and descriptions overlapping with embodiment 1 will be omitted. FIG. 15 is a first flowchart showing the operation of the transmitting device 2 according to embodiment 2. Note that in the flowchart shown in FIG. 15, the operations from step S1 to step S3 are the same as the operations from step S1 to step S3 in the flowchart of embodiment 1 shown in FIG. 2. In embodiment 2, the modulator 12 outputs the generated modulated signal to the transmit diversity unit 13.

[0039] In the transmitting device 2 shown in Fig. 14, the transmit diversity unit 13 acquires a modulated signal from the modulator 12. The transmit diversity unit 13 applies transmit diversity to the modulated signal acquired from the modulator 12 to generate a transmit diversity signal (step S4). The transmit diversity unit 13 applies transmit diversity, such as a space-time block coding (STBC) method, to the modulated signal acquired from the modulator 12 to generate a transmit diversity signal. The transmit diversity unit 13 outputs the generated transmit diversity signal to the symbol sorter 14.

[0040] The symbol sorter 14 acquires a transmit diversity signal from the transmit diversity unit 13. The symbol sorter 14 sorts the transmit diversity signal acquired from the transmit diversity unit 13 so that mapped symbol sequences for the same information bit sequence are output consecutively in time (step S5). The symbol sorter 14 sorts the multiple transmit diversity signals acquired from the transmit diversity unit 13 so that the amount of envelope fluctuation is constant, and outputs the sorted signals. In other words, the symbol sorter 14 rearranges the multiple transmit diversity signals so that signals symbol-mapped for the same information bit sequence are output consecutively in time, so that the amount of envelope fluctuation is suppressed, and outputs the signals.

[0041] Next, a description will be given of a characteristic operation of the transmitting device 2 in this embodiment. Note that, as in the first embodiment, the description will be given here by taking as an example a case where the modulation method is a π / 4 shift QPSK method, the number of mapping symbols is 4, the leading symbol is fixed, and an STBC method with two transmitting antennas is applied as transmission diversity, but the number of transmitting antennas, the transmission diversity method, etc. are not limited to these.

[0042] 16 is a first diagram showing a processing image in the transmitting device 2 according to embodiment 2. In the transmitting device 2, first, the mapping rule generating unit 10 generates a mapping rule based on information such as the number of mapping symbols.

[0043] The symbol mapping unit 11 performs symbol mapping on the input information bit string of two symbols based on the mapping rule generated by the mapping rule generation unit 10. For example, as shown in FIG. １ , s ２ The symbol mapping unit 11 receives the information bit string s １ , s ２ For the mapping symbol sequence, s １１ , s １２ , s １３ , s １４ , and s ２１ , s ２２ , s ２３ , s ２４ In the first embodiment, the symbol mapping unit 11 generates s １１ In contrast to the second embodiment, the signals are output to the modulation unit 12 in order from s １１ , s ２１ , s １２ , s ２２ , s １３ , s ２３ , s １４ , s ２４ The signals are output to the modulation unit 12 in this order.

[0044] The modulation unit 12 modulates the acquired mapping symbol sequence by the π / 4 shift QPSK method in accordance with the signal point constellation diagram shown in FIG. 5 to generate a modulated signal, which is output to the downstream transmission diversity unit 13 .

[0045] The transmit diversity unit 13 applies transmit diversity between two consecutive symbols. For example, the transmit diversity unit 13 applies STBC coding given by equation (1) described in the following document to a modulated signal of two consecutive symbols to generate signals for two transmit antennas.

[0046] (Reference) S. M. Alamouti, "A Simple Transmit Diversity Technique for Wireless Communications", IEEE Journal on Select Areas in Communications, Vol.16, No.8, pp.1451-1458, October 1998.

[0047]

[0048] In formula (1), z ｉ (i=1, 2) indicates the i-th symbol among the symbols to which STBC is applied, and x ｉ （ＴＸ＃Ｎ） denotes the i-th diversity signal at the N-th transmit antenna, and (·) ＊ denotes a complex conjugate. Note that the STBC encoding is not limited to the example of equation (1).

[0049] As shown in the first embodiment, the symbol mapping unit 11 performs symbol mapping on the information bit string based on the mapping rule generated by the mapping rule generation unit 10, thereby obtaining a combined gain while suppressing an increase in the amount of envelope fluctuation. However, as shown in Fig. 16, in the diversity signals generated by the transmit diversity unit 13 for each transmitting antenna, mapping symbols for different information bit strings are output alternately in time, and in this case, there is a concern that the amount of envelope fluctuation may increase.

[0050] Therefore, in this embodiment, the symbol sorting unit 14 sorts the transmit diversity signal so that mapping symbol sequences for the same information bit sequence are output consecutively in time, in order to suppress an increase in the amount of envelope fluctuation. For example, in the example shown in FIG. 16, the transmit diversity unit 13 outputs "s １１ , -s ２１ ＊ , s １２ , -s ２２ ＊ , s １３ , -s ２３ ＊ , s１４ , -s ２４ ＊ In response to this, the symbol sorting unit 14 outputs the acquired transmission diversity signals in the order of "s １１ , s １２ , s １３ , s １４ , -s ２１ ＊ , -s ２２ ＊ , -s ２３ ＊ , -s ２４ ＊ In this way, the symbol sorting unit 14 sorts the data in mapping symbol units.

[0051] As a result, the symbol sorting unit 14 outputs signals symbol-mapped for the same information bit string in a time-series manner, thereby suppressing an increase in the amount of envelope fluctuation.

[0052] FIG. 17 is a second diagram showing a configuration example of a transmitting device 2 according to embodiment 2. The transmitting device 2 shown in FIG. 14 includes a symbol sorting unit 14 that sorts the transmit diversity signal after the transmit diversity unit 13 so as to suppress an increase in the amount of envelope fluctuation. However, the transmitting device 2 shown in FIG. 17 eliminates the symbol sorting unit 14 by having the transmit diversity unit 13 sort the transmit diversity signal before outputting it so as to suppress an increase in the amount of envelope fluctuation. FIG. 18 is a second flowchart showing the operation of the transmitting device 2 according to embodiment 2. Note that, in the flowchart shown in FIG. 18, the operations from step S1 to step S3 are the same as the operations from step S1 to step S3 in the flowchart of embodiment 1 shown in FIG. 2. In embodiment 2, the modulator 12 outputs the generated modulated signal to the transmit diversity unit 13.

[0053] In the transmitting device 2 shown in Fig. 17, the transmit diversity unit 13 acquires modulated signals from the modulator 12. The transmit diversity unit 13 applies transmit diversity to the modulated signals acquired from the modulator 12 to generate transmit diversity signals, and outputs the transmit diversity signals in an order that suppresses an increase in the amount of envelope fluctuation (step S6). The transmit diversity unit 13 applies transmit diversity to multiple modulated signals between signals with the same mapping symbol number, and generates and outputs transmit diversity signals that are symbol mapped so that the amount of envelope fluctuation is suppressed.

[0054] 19 is a second diagram showing a processing image in the transmitting device 2 according to the second embodiment. In the operation shown in FIG. 16, the symbol mapping unit 11 performs symbol mapping on two input information bit strings based on a mapping rule, and then performs s １ and s ２ In contrast to this, in the operation shown in FIG. 19, the symbol mapping unit 11 performs symbol mapping on one input information bit string based on the mapping rule as in the first embodiment and outputs the result. Thereafter, the modulation unit 12 generates a modulated signal. The transmission diversity unit 13 alternately outputs a plurality of symbols s to which transmission diversity is applied as shown in FIG. １ (s １１ , s １２ , s １３ , s １４ ), s ２ (s ２１ , s ２２ , s ２３ , s ２４ ), the s between signals with the same mapping symbol number １１ and s ２１ , s １２ and s ２２ , .... In this way, the transmit diversity unit 13 applies transmit diversity between signals having the same mapping symbol number among two consecutive symbols.

[0055] As a result, even in the configuration shown in FIG. 17, the transmitting device 2 can acquire a transmit diversity signal that has been symbol mapped so as to suppress an increase in the amount of envelope fluctuation.

[0056] In this embodiment, transmit diversity is applied between mapping symbol sequences corresponding to different information bit sequences, but the combination is not limited to the examples shown in Figures 16 and 19 as long as the amount of envelope fluctuation of the signal after transmit diversity is suppressed.

[0057] As described above, according to this embodiment, the transmitting device 2 generates and applies a mapping rule that can obtain a combined gain while suppressing an increase in the amount of envelope fluctuation even when transmit diversity is applied, thereby achieving the effects of improving power efficiency and required received power.

[0058] The configurations shown in the above embodiments are merely examples, and may be combined with other known technologies, or different embodiments may be combined with each other. It is also possible to omit or modify parts of the configurations as long as they do not deviate from the gist of the invention.

[0059] 1, 2 transmitter, 10 mapping rule generation unit, 11 symbol mapping unit, 12 modulation unit, 13 transmission diversity unit, 14 symbol sorting unit, 90, 93 processing circuit, 91 processor, 92 memory

Claims

1. A transmitting device comprising: a mapping rule generating unit that generates a mapping rule that suppresses an increase in the amount of envelope fluctuation; a symbol mapping unit that performs symbol mapping on an input information bit sequence based on said mapping rule to generate a mapping symbol sequence; and a modulation unit that generates a modulated signal for said mapping symbol sequence using a Phase Shift Keying modulation method that shifts a reference phase by a specified phase for each symbol timing.

2. The transmitting device according to claim 1, further comprising a transmit diversity section that applies transmit diversity to the modulated signal to generate a transmit diversity signal and outputs the transmit diversity signal in an order that suppresses an increase in the amount of envelope fluctuation.

3. The transmitting device according to claim 2, characterized in that the transmit diversity unit applies the transmit diversity between signals with the same mapping symbol number for a plurality of the modulated signals, and generates and outputs the transmit diversity signal that is symbol mapped so as to suppress the amount of envelope fluctuation.

4. The transmitting device according to claim 1, further comprising: a transmit diversity section that applies transmit diversity to the modulated signal to generate a transmit diversity signal; and a symbol sort section that sorts the transmit diversity signal so that mapping symbol sequences for the same information bit sequence are output consecutively in time.

5. The transmitting device according to claim 4, characterized in that the symbol sorting unit rearranges the signals so that signals symbol-mapped to the same information bit sequence are output consecutively in time for the plurality of transmit diversity signals, thereby suppressing the amount of envelope fluctuation.

6. The transmitting device according to any one of claims 1 to 5, wherein the mapping rule generating section generates the mapping rule that suppresses an increase in the amount of envelope fluctuation based on the modulation method.

7. A transmitting device according to any one of claims 1 to 6, characterized in that the mapping rule generation unit generates the mapping rule that suppresses an increase in the amount of envelope fluctuation for a specified number of mapping symbols.

8. A transmitting device according to any one of claims 1 to 7, characterized in that the mapping rule generating section generates the mapping rule that suppresses an increase in the amount of envelope fluctuation depending on whether or not a known symbol is present.

9. A transmitting device according to any one of claims 1 to 8, characterized in that the mapping rule generation unit determines the number of mapping symbols based on the propagation conditions of wireless communication, and generates the mapping rule that suppresses an increase in the amount of envelope fluctuation.

10. A control circuit for controlling a transmitting device, the control circuit causing the transmitting device to perform the following: generating a mapping rule that suppresses an increase in envelope fluctuation; performing symbol mapping on an input information bit string based on said mapping rule to generate a mapping symbol string; and generating a modulated signal for said mapping symbol string using a Phase Shift Keying modulation method that shifts a reference phase by a specified phase for each symbol timing.

11. A storage medium storing a program for controlling a transmitting device, the program causing the transmitting device to perform the following: generate a mapping rule that suppresses an increase in envelope fluctuation amount; perform symbol mapping on an input information bit string based on the mapping rule to generate a mapping symbol string; and generate a modulated signal using a Phase Shift Keying modulation method that shifts a reference phase by a specified phase for each symbol timing for the mapping symbol string.

12. A transmission method comprising: a mapping rule generation step in which a mapping rule generation unit generates a mapping rule that suppresses an increase in the amount of envelope fluctuation; a symbol mapping step in which a symbol mapping unit performs symbol mapping on an input information bit sequence based on the mapping rule to generate a mapping symbol sequence; and a modulation step in which a modulation unit generates a modulated signal using a Phase Shift Keying modulation method that shifts a reference phase by a specified phase for each symbol timing for the mapping symbol sequence.

13. The transmission method according to claim 12, further comprising a transmit diversity step in which a transmit diversity unit applies transmit diversity to the modulated signal to generate a transmit diversity signal, and outputs the transmit diversity signal in an order in which an increase in the amount of envelope fluctuation is suppressed.

14. The transmission method according to claim 12, further comprising: a transmission diversity step in which a transmission diversity unit applies transmission diversity to the modulated signal to generate a transmission diversity signal; and a symbol sorting step in which a symbol sorting unit sorts the transmission diversity signal so that mapping symbol sequences for the same information bit sequence are output consecutively in time.

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