Receiver, wireless communication system, and wireless receiving method

Abstract

To achieve wireless communication in which in a receiver, the transmission rate of information bits is not reduced and the SNR versus BER performance for the information bits is not deteriorated.SOLUTION: A receiver 2 includes a frame detection unit 25 that, in each of predetermined phase shift sections of a plurality of subframes, detects the phase shift section for a modulated received symbol that has been phase-rotated in a predetermined amount of phase rotation, a phase inverse shift unit 28 that phase-rotates the modulated received symbol in the detected phase shift section so as to cancel out the amount of phase rotation, and a demodulation unit 29 that demodulates the modulated received symbol that has been phase-rotated so as to cancel out the amount of phase rotation to restore transmission data. The amount of phase rotation is determined based on a unique word, which is a predetermined bit string that identifies the start position of each of the plurality of subframes.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a receiver, a wireless communication system, and a wireless receiving method. [Background technology]

[0002] Generally, in wireless communication systems, transmission data is divided into subframes for transmission, but a unique word must be transmitted in order for the receiver to identify the start position of the subframe. Hereinafter, the bits that contain the transmission data in the subframe are called information bits. Also, the bits that contain the unique word in the subframe are called UW (Unique Word) bits.

[0003] For example, Patent Document 1 discloses a technique of inserting a unique word into a subframe as a UW bit as a general method of transmitting a unique word. Also, Non-Patent Document 1 discloses a WCDMA system (registered trademark) as another method of transmitting control information including a unique word, in which a bit pattern including one information bit and one UW bit is assigned to the in-phase component (I axis) and quadrature component (Q axis) of QPSK (Quadrature Phase-Shift Keying). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2015-50686 A [Non-patent literature]

[0005] [Non-Patent Document 1] Yasuyuki Oishi, Morihiko Minowa, Ryuji Nakamura, "FUJITSU Magazine" January 2000 issue, Vol. 51, No. 1, pp. 13-18 Summary of the Invention [Problem to be solved by the invention]

[0006] In the wireless communication method disclosed in Patent Document 1, it is necessary to increase the number of UW bits in order to improve the detection accuracy of the subframe timing for identifying the start position of the subframe. However, as the number of UW bits is increased, the number of information bits that can be transmitted per subframe decreases by the number of UW bits, so that the transmission speed of the information bits decreases. In addition, in the wireless communication method disclosed in Non-Patent Document 1, since the information bits and the UW bits are transmitted by the same symbol modulated by QPSK, even if the number of UW bits is increased, the number of information bits does not decrease compared to the number of bits in the case of transmission by BPSK (Binary Phase-Shift Keying), and the transmission speed of the information bits does not decrease. However, since the information bit included in each symbol is one bit, it is transmitted by QPSK, so there is a problem that the SNR (Signal-to-Noise power Ratio) vs. BER (Bit Error Rate) performance for the information bits deteriorates compared to the BPSK method in which the UW bit and the information bit are transmitted by different symbols.

[0007] The present disclosure has been made to solve the above-mentioned problems, and aims to realize wireless communication in which the transmission speed of information bits is not reduced and the SNR vs. BER performance for information bits is not deteriorated. [Means for solving the problem]

[0008] In order to achieve the above object, a receiver according to the present disclosure receives a transmission high frequency signal generated by phase shift keying transmission data divided into a plurality of subframes, and reproduces the signal as a modulated reception symbol, and includes a frame detection unit, a phase inverse shift unit, and a demodulation unit. The frame detection unit detects a phase shift section, which is a predetermined section, in which the phase of the modulated reception symbol is rotated by a predetermined amount of phase rotation in a predetermined section of each of the plurality of subframes. The phase inverse shift unit rotates the phase of the modulated reception symbol in the detected phase shift section so as to cancel the predetermined amount of phase rotation, thereby generating a phase inverse shifted reception symbol. The demodulation unit demodulates the phase inverse shifted reception symbol to restore the transmission data. The predetermined amount of phase rotation of the modulated reception symbol is determined based on a unique word, which is a predetermined bit string that specifies the start position of each of the plurality of subframes.

[0009] The wireless communication system according to the present disclosure includes a transmitter that converts transmission symbols generated by performing phase shift keying on transmission data divided into a plurality of subframes into a transmission high-frequency signal and transmits the signal, and a receiver that receives the transmission high-frequency signal, reproduces the transmission high-frequency signal as a modulated reception symbol, and demodulates the modulated reception symbol to restore the transmission data. The transmitter includes a modulation unit and a phase shift unit. The modulation unit performs phase shift keying on the transmission data divided into a plurality of subframes to generate phase shift keying symbols. The phase shift unit phase rotates the phase shift keying symbols by a predetermined phase rotation amount in a predetermined section of each of the plurality of subframes to generate transmission symbols. The receiver includes a frame detection unit, a phase inverse shift unit, and a demodulation unit. The frame detection unit detects a phase shift section that is a predetermined section in which the modulated reception symbol is phase rotated by a predetermined phase rotation amount. The phase inverse shift unit phase rotates the modulated reception symbol in the detected phase shift section so as to cancel the predetermined phase rotation amount, thereby generating a phase inverse shifted reception symbol. The demodulation unit demodulates the received symbols after the phase inverse shift to restore the transmission data. The predetermined phase rotation amount of the transmission symbols is determined based on a unique word, which is a bit string known to both the transmitter and the receiver, that specifies the start position of each of the multiple subframes.

[0010] Moreover, a wireless receiving method according to the present disclosure is a wireless receiving method for receiving a transmitted high-frequency signal generated by phase shift keying transmission data divided into a plurality of subframes, and reproducing the signal as a modulated received symbol, the method comprising: detecting a phase shift section which is a predetermined section in which the phase is rotated for the modulated received symbol which has been phase-rotated by a predetermined amount of phase rotation in a predetermined section of each of the plurality of subframes; phase rotating the modulated received symbol in the detected phase shift section so as to cancel out the predetermined amount of phase rotation to generate a reverse-phase-shifted received symbol; and demodulating the reverse-phase-shifted received symbol to restore the transmission data, the predetermined amount of phase rotation of the modulated received symbol being determined based on a unique word which is a predetermined bit string which identifies the start position of each of the plurality of subframes. Effect of the Invention

[0011] According to the present disclosure, by detecting a phase shift section of a modulated received symbol that has been phase-rotated by a predetermined phase rotation amount based on a unique word, and then performing phase rotation on the modulated received symbol in the detected phase shift section so as to cancel out the predetermined phase rotation amount, and then demodulating the symbol, it is possible to realize wireless communication in which the transmission speed of information bits is not reduced and the SNR vs. BER performance for the information bits is not deteriorated. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a block diagram showing an example of the configuration of a transmitter and a receiver according to a first embodiment; [Diagram 2] FIG. 1 is a diagram showing an example of processing performed by a modulation section and a phase shift section according to the first embodiment; [Diagram 3] FIG. 1 shows a subframe configuration according to the prior art. [Figure 4] FIG. 1 is a block diagram showing a configuration example of a frame detection unit according to a first embodiment; [Diagram 5] FIG. 1 is a diagram showing an example of a process performed by a frame detection unit according to the first embodiment; [Figure 6] Flowchart showing reception processing according to the first embodiment [Figure 7] FIG. 11 is a block diagram showing a configuration example of a frame detection unit according to a second embodiment. [Figure 8] FIG. 13 is a diagram showing an example of a process performed by a frame detection unit according to the second embodiment; [Figure 9] FIG. 13 is a diagram showing an example of LLR calculation according to the second embodiment; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, a wireless communication device according to the present embodiment will be described in detail with reference to the drawings. Note that in the drawings, the same or corresponding parts are designated by the same reference characters, and their description will not be repeated in principle.

[0014] (Embodiment 1) 1 shows an example of the configuration of a wireless communication system 100 according to the embodiment 1. The wireless communication system 100 includes a transmitter 1 that wirelessly transmits transmission data, and a receiver 2 that receives the transmission data from the transmitter 1.

[0015] The transmitter 1 includes a transmission data generator 11 that generates transmission data, a frame generator 12 that generates a transmission frame from the transmission data, and a modulator 13 that modulates the transmission frame with PSK (Phase Shift Keying) to generate a PSK modulation symbol. Here, PSK modulation refers to changing the phase of a carrier wave to a plurality of phases according to a predetermined rule, and transmitting digital data by assigning a bit pattern to each of the plurality of phases. Also, a PSK modulation symbol refers to a state in which a bit pattern is assigned to the IQ (in-phase axis-quadrature axis) plane of a PSK modulation signal. A PSK modulation symbol is sometimes simply called a symbol.

[0016] The transmitter 1 also includes a unique word output unit 14 that outputs a known unique word to a phase shift unit 15, the phase shift unit 15 that rotates the phase of the PSK modulation symbol in accordance with the input unique word to generate a transmission symbol, a transmission filter 16 that performs band limiting on the transmission symbol to generate a transmission digital baseband signal, which is a digital signal, and a DAC (Digital Analog Converter) 17 that performs D / A conversion on the transmission digital baseband signal to generate a transmission analog baseband signal, which is an analog signal.

[0017] The transmission data generating unit 11 generates transmission data, which is digital data to be wirelessly transmitted. For example, in a system for wirelessly transmitting IP (Internet Protocol) data input from an external device, CRC (Cyclic Redundancy Check) bits are added to the IP data as check bits for error detection, and error correction coding is performed using a convolutional code to obtain transmission data.

[0018] Frame generation unit 12 generates a transmission frame by dividing the transmission data generated by transmission data generation unit 11 into subframe units. For example, in a system in which one transmitter 1 wirelessly transmits transmission data to multiple receivers 2 in a time-division manner, the transmission frame is made up of multiple time-division subframes, and each piece of time-division transmission data is included in a subframe corresponding to the destination receiver 2. The subframes may be transmitted continuously, or may be transmitted in a burst that includes a transmission OFF period that does not include transmission data between subframes.

[0019] The modulation unit 13 performs PSK modulation on the information bits in the transmission frame input from the frame generation unit 12 to generate a PSK modulation symbol. The PSK modulation symbol is also called a phase shift keying symbol. The mapping rule follows the Gray code. That is, the Hamming distance between each information bit sequence assigned to each ideal symbol point adjacent to each other at the minimum distance on the IQ plane is 1. For example, in the case of BPSK modulation, the modulation unit 13 maps the information bit "1" to "1" on the IQ plane and maps the information bit "0" to "-1" on the IQ plane to generate a PSK modulation symbol. The present disclosure is not limited to BPSK modulation. For example, in the case of QPSK modulation, the modulation unit 13 maps the information bit "11" to "1" on the IQ plane, maps the information bit "01" to "j" on the IQ plane, maps the information bit "00" to "-1" on the IQ plane, and maps the information bit "10" to "-j" on the IQ plane to generate a PSK modulation symbol. j is an imaginary unit. In general, the modulation unit 13 can generate M-ary PSK modulation symbols, and the M value can be determined appropriately (M=2 1 , 2 2 , , 2 n :n is a natural number).

[0020] The unique word output by the unique word output unit 14 is a bit string known to both the transmitter 1 and the receiver 2. For example, the unique word may be a pseudo-random number sequence such as an M sequence, a Gold sequence, a ZC (Zadoff-Chu) sequence, or a PN (Pseudorandom Noise) sequence generated by a shift register. Alternatively, an arbitrary random pattern created in advance may be written to a non-volatile memory, and the random pattern may be read out at a required timing to be used as the unique word. Note that the above unique word is merely an example, and is not limited to the above bit string as long as it is a bit string suitable for detecting a subframe.

[0021] The phase shift unit 15 regularly rotates the phase of symbols in a predetermined frame section in each subframe, among the PSK modulated symbols input from the modulation unit 13, based on the unique word input from the unique word output unit 14, to generate transmission symbols. Here, the predetermined frame section in which the phase of the PSK modulated symbols in each subframe is regularly rotated based on the unique word is defined as a phase shift section. Furthermore, the symbols in the phase shift section function as a unique word.

[0022] For example, when the modulation unit 13 performs BPSK modulation, the phase shift unit 15 performs a phase rotation of π / 2 on the k-th PSK modulation symbol in the phase shift interval when the k-th bit of the unique word is "1", and performs a phase rotation of 0 on the k-th PSK modulation symbol in the phase shift interval when the k-th bit of the unique word is "0". k is a natural number. For example, when the modulation unit 13 performs QPSK modulation, the phase shift unit 15 performs a phase rotation of π / 4 on the k-th PSK modulation symbol in the phase shift interval when the k-th bit of the unique word is "1", and performs a phase rotation of 0 on the k-th PSK modulation symbol in the phase shift interval when the k-th bit of the unique word is "0". In general, when the modulation unit 13 performs M-ary PSK modulation, the phase shift unit 15 performs a phase rotation of π / M (M=2 1 , 22 , , 2 n When the k-th bit of the unique word is "0", a phase rotation of 0 is performed on the k-th PSK modulated symbol in the phase shift section. Here, the amount of phase rotation that the phase shift unit 15 applies to the PSK modulated symbol is called the amount of phase rotation or the amount of phase shift.

[0023] As a result of the process performed by the phase shift unit 15, the modulation level of the transmission symbol in the phase shift section becomes twice that of the PSK modulation symbol generated by the modulation unit 13. For example, if the modulation level of the PSK modulation symbol generated by the modulation unit 13 is 2 (BPSK), the modulation level of the transmission symbol in the phase shift section becomes 4 (QPSK). Here, for example, when BPSK modulation is performed by the modulation unit 13, the mapping rule of the BPSK modulation symbol follows the Gray code. However, the mapping rule of the phase-rotated transmission symbol with the modulation level of 4 does not follow the Gray code. In general, the mapping rule of the symbol when phase shift keying the transmission data follows the Gray code, but the mapping rule of the transmission symbol or the modulated reception symbol phase-rotated by a predetermined phase rotation amount does not follow the Gray code.

[0024] Here, the processing performed by the modulation unit 13 and the phase shift unit 15 will be described with reference to FIG. 2. FIG. 2(a) shows the processing performed by the modulation unit 13, and illustrates an arrangement diagram of PSK modulation symbols. In the example of FIG. 2(a), the modulation unit 13 maps the information bit "1" of the transmission frame to "1" on the IQ plane, and the information bit "0" of the transmission frame to "-1" on the IQ plane to generate PSK modulation symbols. Here, the PSK modulation symbols are "1" and "-1" on the complex plane. FIG. 2(b) shows the processing performed by the phase shift unit 15, and illustrates an arrangement diagram of transmission symbols. In the example of FIG. 2(b), when the unique word output from the unique word output unit 14 is a bit string of "110101" consisting of 6 bits, the phase shift unit 15 rotates the phase of the PSK modulation symbols from the first to sixth subframes (phase shift section) to generate transmission symbols. The phase shift unit 15 does not rotate the phase of the PSK modulation symbol outside the phase shift interval of the subframe. The phase shift unit 15 rotates the phase of the kth symbol in the phase shift interval based on the kth (k is a natural number: 1≦k≦6) bit value of the unique word. For example, when the kth bit value of the unique word is "1", a phase rotation of π / 2 is performed on the kth symbol in the phase shift interval, and when the kth bit value of the unique word is "0", a phase rotation of 0 is performed on the kth symbol in the phase shift interval. Note that the unique word is not limited to 6 bits. For example, the number of bits of the unique word may be increased so that the unique word is assigned to the entire subframe. In addition, the phase shift interval does not have to start from the beginning of the subframe. In other words, the phase shift interval may be a part of the subframe or the entire subframe. When the unique word is assigned to the entire subframe, the entire subframe becomes the phase shift interval.

[0025] In the conventional technology, as shown in Fig. 3, a unique word is inserted as a UW bit in a predetermined section of a subframe, and the receiver detects the unique word to perform frame synchronization. This technology requires a UW bit in the subframe, which causes a problem that the transmission speed of the information bits is reduced compared to the case where only information bits are transmitted. In contrast, the wireless communication system 100 of the first embodiment does not require a UW bit, so the transmission speed of the information bits does not decrease.

[0026] 1, the transmit filter 16 generates a transmit digital baseband signal by oversampling the transmit symbol input from the phase shift unit 15 to the sampling rate of the DAC 17 and then shaping the waveform. For example, the transmit filter 16 uses a root Nyquist filter.

[0027] The DAC 17 converts the transmission digital baseband signal input from the transmission filter 16 into an analog signal (DA conversion) to generate a transmission analog baseband signal. The transmission mixer converts the frequency of the transmission analog baseband signal to a higher transmission frequency band (up-conversion) to generate a transmission high-frequency signal. The transmission high-frequency signal is power-amplified by the transmission amplifier and wirelessly transmitted from the transmission antenna. The transmission filter 16, the DAC 17, the transmission mixer, the transmission amplifier, and the transmission antenna are an example of a transmission unit.

[0028] The receiver 2 includes an ADC (Analog Digital Converter) 21 that converts a received transmitted high frequency signal into a digital signal (AD conversion) and generates a received digital baseband signal, a receive filter 22 that performs band limiting on the received digital baseband signal to generate received symbols, a clock recovery unit 23 that performs clock recovery on the received symbols to generate received symbols after clock recovery, and a carrier recovery unit 24 that performs carrier recovery on the received symbols after clock recovery, to generate received symbols after carrier recovery.

[0029] The receiver 2 also includes a frame detection unit 25 that detects subframes for the received symbols after carrier recovery and outputs subframe timing at the detected timing, a symbol delay unit 26 that delays the received symbols after carrier recovery by the number of bits of a unique word to generate delayed-adjusted received symbols, a unique word output unit 27 that outputs a known unique word to a phase inverse shift unit 28, a phase inverse shift unit 28 that inversely shifts the phase of symbols in the phase shift section of the delayed-adjusted received symbols identified based on the subframe timing input from the frame detection unit 25, in accordance with the input unique word, to generate delayed-adjusted received symbols, a demodulation unit 29 that demodulates the delayed-adjusted received symbols to generate demodulated bits, a frame separation unit 30 that separates the demodulated bits into subframe units based on the subframe timing to generate received subframes, and a received data separation unit 31 that restores transmission data from the received subframes.

[0030] The transmitted high frequency signal input to the receiving antenna is power amplified by the receiving amplifier and converted (down-converted) to a lower frequency baseband band by the receiving mixer to generate a received analog baseband signal. The ADC 21 performs AD conversion on the received analog baseband signal to generate a received digital baseband signal.

[0031] The receiving filter 22 generates a receiving symbol by removing unnecessary signals outside the frequency band of the received digital baseband signal input from the ADC 21. For example, the receiving filter 22 uses a root Nyquist filter. The present disclosure is not limited to the root Nyquist filter. It is sufficient that the configuration of the transmitting filter 16 and the configuration of the receiving filter 22 are the same. The receiving antenna, the receiving amplifier, the receiving mixer, the ADC 21, and the receiving filter 22 are an example of a receiving unit.

[0032] The clock recovery unit 23 estimates the center timing of the received symbol input from the receiving filter 22, and generates a received symbol after clock recovery by selecting and outputting only the samples at the center timing.

[0033] The carrier recovery unit 24 corrects frequency errors and recovers symbol phases for the post-clock recovery reception symbols input from the clock recovery unit 23, using, for example, a Costas loop method or a frequency multiplication method, and generates post-carrier recovery reception symbols. The post-carrier recovery reception symbols are also called modulated reception symbols. The carrier recovery unit 24 recovers the symbol phase, taking into consideration that the transmission symbols in the phase shift section have twice the multi-value number of the PSK modulation symbols generated by the modulation unit 13. For example, if the PSK modulation symbols generated by the modulation unit 13 are BPSK modulation symbols, the carrier recovery unit 24 recovers the symbol phase, taking into consideration that the transmission symbols are QPSK modulation symbols.

[0034] The frame detection unit 25 determines the quadrant of the symbol point of the post-carrier recovery reception symbol input from the carrier recovery unit 24 based on the deflection angle of the post-carrier recovery reception symbol, and calculates the UW bit decision value. In the first embodiment, the post-carrier recovery reception symbol is subjected to hard decision, and the result of the hard decision is calculated as the UW bit hard decision value. The hard decision is to determine the post-carrier recovery reception symbol point arranged on the IQ plane as a binary value of "0" or "1" based on a threshold value for the deflection angle of the post-carrier recovery reception symbol point. Therefore, the UW bit hard decision value is either "0" or "1". For example, if the post-carrier recovery reception symbol is a QPSK modulation symbol, when the deflection angle (θ: -π≦θ<π) of the post-carrier recovery reception symbol point is π / 4<|θ|≦π3 / 4, the UW bit hard decision value is "1", and when it is other than π / 4<|θ|≦π3 / 4, the UW bit hard decision value is "0". For example, if the symbol after carrier recovery is an 8PSK modulation symbol, the UW bit hard decision value is "1" if the argument (θ) of the received symbol point after carrier recovery is π / 8<|θ|≦π3 / 8 or π5 / 8<|θ|≦π7 / 8, and is "0" if other than π / 8<|θ|≦π3 / 8 or π5 / 8<|θ|≦π7 / 8. Here, the UW bit hard decision value is also called the UW bit decision value. In general, if the argument (θ) of the received symbol point after carrier recovery is (2m-1)π / 2M<|θ|≦(2m+1)π / 2M (m=1, 2, . . . , 2M / 2-1), the UW bit hard decision value is "1", and if other than (2m-1)π / 2M<|θ|≦(2m+1)π / 2M, the UW bit hard decision value is "0".

[0035] Here, the configuration of the frame detection unit 25 will be described with reference to Fig. 4. The frame detection unit 25 includes a UW bit hard decision unit 251 that performs hard decision on the received symbol after carrier recovery and calculates a UW bit hard decision value, a shift register 252 that stores the UW bit hard decision value, a unique word output unit 253 that outputs a known unique word to an error bit number calculation unit 254, an error bit number calculation unit 254 that compares the input unique word with the UW bit hard decision value to calculate the number of error bits, and an allowable error bit number comparison unit 255 that detects subframes by determining whether the number of error bits exceeds the allowable error bit number.

[0036] The process performed by the frame detection unit 25 will be described with reference to Fig. 5. The UW bit hard decision unit 251 performs hard decision on the received symbols after carrier recovery by quadrant decision. The UW bit hard decision values ​​of the received symbols after carrier recovery, which have been subjected to hard decision for the 10 received symbols after carrier recovery including the unique word shown in Fig. 5, are "0011010100" from the left in the figure. The shift register 252 stores, of the UW bit hard decision values ​​input from the UW bit hard decision unit 251, the UW bit hard decision value corresponding to the number of bits of the unique word.

[0037] When the unique word output from the unique word output unit 253 is "110101", which is 6 bits, the 6-bit UW bit hard decision value is stored in the shift register 252. The error bit number calculation unit 254 compares the k-th bit value of the UW bit hard decision value with the k-th bit value of the unique word, and calculates the number of error bits by summing up the number of differences between the k-th bit value of the UW bit hard decision value and the k-th bit value of the unique word. For example, the 6-bit UW bit hard decision value "001101" from the first to sixth symbols from the left among the 10 carrier recovery symbols shown in FIG. 5 has a number of error bits of 3 compared to the unique word "110101". The next 6-bit UW bit hard decision value "011010" from the second to seventh symbols after carrier recovery has a number of error bits of 5 compared to the unique word "110101". The number of error bits in the 6-bit UW bit hard decision value "110101" of the next 3rd to 8th symbols after carrier recovery is compared with the unique word "110101." In other words, the bit value of the unique word is compared with the UW bit hard decision value corresponding to the number of bits of the unique word, and the number of different bit values ​​is calculated as the number of error bits.

[0038] The allowable error bit number comparison unit 255 detects the phase shift section by comparing the number of error bits input from the error bit number calculation unit 254 with a predetermined allowable error bit number, and outputs the subframe timing to the phase inverse shift unit 28 and the frame separation unit 30 at the detected timing. Since the symbol phase recovery result in the carrier recovery unit 24 is uncertain, the UW bit hard decision value may have bits inverted with respect to the unique word. Therefore, if the number of error bits satisfies either the allowable error bit number or less, or the number of error bits is equal to or greater than the value obtained by subtracting the allowable error bit number from the number of bits of the unique word, the unique word is determined to be unique, and the phase shift section is detected. For example, if the number of unique word bits is 32 and the allowable error bit number is 2, the phase shift section is detected if the number of error bits is 2 or less, or if the number of error bits is 30 or more (32-2). The determination of whether the number of error bits exceeds the allowable number of error bits is an example of detecting a phase shift section, which is a predetermined section in which the phase is rotated, for a modulated received symbol that has been phase-rotated by a predetermined amount of phase rotation in a predetermined section of each of a plurality of subframes.

[0039] 5, if the allowable error bit number is 0, the allowable error bit number comparison unit 255 detects a phase shift section if the error bit number is 0 or 6. The allowable error bit number comparison unit 255 compares the unique word "110101" to determine that the six UW bit hard decision values ​​with the error bit number of 0 are unique words, and detects a phase shift section.

[0040] As shown in Fig. 1, the symbol delay unit 26 applies a delay to the carrier-recovered received symbol input from the carrier recovery unit 24 by the number of bits of a unique word to generate a delay-adjusted received symbol. The symbol delay unit 26 may generate a known unique word, or may receive a unique word from the unique word output unit 27. The timing at which the frame detection unit 25 completes detection of the phase shift interval is the end of the phase shift interval. Thus, by delaying the carrier-recovered symbol by the number of bits of the unique word, it is possible to match the start of the phase shift interval of the delay-adjusted received symbol with the subframe timing output by the frame detection unit 25.

[0041] The phase inverse shift unit 28 specifies a phase shift interval for the delay-adjusted received symbols input from the symbol delay unit 26, based on the subframe timing input from the frame detection unit 25. The phase inverse shift unit 28 performs phase rotation on the delay-adjusted received symbols in the specified phase shift interval among the delay-adjusted received symbols, based on the unique word, to cancel out the phase shift performed by the transmitter 1, and generates a phase-inverse-shifted received symbol. Phase rotation is not performed on the delay-adjusted received symbols outside the phase shift interval. For example, in the case where a BPSK modulated symbol is generated by canceling the phase rotation, the phase inverse shift unit 28 performs a phase rotation of -π / 2 on the kth delay-adjusted received symbol in the phase shift interval when the kth bit value of the unique word is "1", and performs a phase rotation of 0 on the kth delay-adjusted received symbol in the phase shift interval when the kth bit value of the unique word is "0". For example, when canceling a phase shift to obtain a QPSK modulated symbol, when the kth bit value of the unique word is "1", a phase rotation of -π / 4 is performed on the kth delay-adjusted received symbol in the phase shift section, and when the kth bit value of the unique word is "0", a phase rotation of 0 is performed on the kth delay-adjusted received symbol in the phase shift section. In other words, when canceling a phase shift to obtain an M-ary PSK modulated symbol, when the kth bit value of the unique word is "1", a phase rotation of -π / M is performed on the kth delay-adjusted received symbol in the phase shift section, and when the kth bit value of the unique word is "0", a phase rotation of 0 is performed on the kth delay-adjusted received symbol in the phase shift section.

[0042] The demodulator 29 demodulates the phase-reverse-shifted received symbol input from the phase-reverse shifter 28 to generate demodulated bits. Since the modulation multi-level number of the phase-reverse-shifted received symbol is equal to that of the PSK modulated symbol in the transmitting device, the error rate performance of the information bits is equivalent to that of the PSK modulated symbol when no phase shift / phase-reverse shift according to the unique word is performed.

[0043] The frame separator 30 obtains received subframes by separating the demodulated bits generated by the demodulator 29 into subframe units based on the subframe timing generated by the frame detector 25. Since the phase shift section within a subframe is known in the receiver 2, the frame separator 30 detects the demodulated bits at the beginning and end of the subframe based on the subframe timing, and separates the demodulated bits into subframe units.

[0044] The received data separator 31 restores the transmission data from the received subframes generated by the frame separator 30. For example, if the transmitter 1 performs error correction coding using a convolutional code, the received data separator 31 performs error correction using Viterbi decoding. Also, for example, if the transmitter 1 provides CRC bits as check bits for error detection, the received data separator 31 performs error detection by CRC check. If there is no error in the received subframe, the received data separator 31 outputs the received subframe with the CRC bits removed to an external device. If there is an error in the received subframe, the received data separator 31 removes the entire received subframe.

[0045] Here, the difference between the reference technology and the receiver 2 of the first embodiment will be described. As the reference technology, there is a technology in which differentially encoded BPSK modulation symbols are periodically inserted between 8PSK symbols for transmission, and the receiving side uses the BPSK modulation symbols for carrier recovery. This technology is intended to solve the problem that, when a pilot signal consisting of known data is inserted at the beginning of a frame in order to estimate the frequency offset amount and the amplitude distortion amount between a transmitter and a receiver, the transmission speed decreases by the amount of the pilot signal. In order to solve such a problem, by inserting differentially encoded BPSK symbols, data is transmitted using BPSK symbols, and the BPSK modulation symbols are made to serve as pilot signals. Since it is no longer necessary to restore the absolute phase on the receiving side, data transmission is possible even with BPSK modulation symbols. This improves the data transmission speed compared to the case of transmitting a known pilot signal using BPSK.

[0046] However, the reference technology does not describe or suggest that the receiving side detects the position of the BPSK modulation symbol and detects the beginning position of the frame. Therefore, it is necessary to transmit a separate UW bit for frame synchronization, as in the above-mentioned conventional technology. It is also possible to transmit the UW bit for frame synchronization using the BPSK modulation symbol, but this means transmitting a symbol dedicated to the UW pattern, as in the configuration of transmitting the UW bit in a unique section such as the beginning of a frame in the above-mentioned conventional technology, and therefore the transmission speed for the information bits is reduced by the amount of the UW bit. In contrast, the receiver 2 of the first embodiment does not require a means for detecting the position of the BPSK modulation symbol and does not need to transmit a separate UW bit for frame synchronization, so the transmission speed for the information bits is not reduced compared to the case of transmitting the UW bit.

[0047] The flow of the reception process executed by the receiver 2 will be described with reference to Fig. 6. The reception process starts when the receiver 2 receives a transmission high frequency signal. The ADC 21 performs AD conversion on the received transmission high frequency signal to generate a reception digital baseband signal (step S11). The reception filter 22 generates a reception symbol by removing unnecessary signals outside the signal band of the reception digital baseband signal input from the ADC 21 (step S12).

[0048] The clock recovery unit 23 estimates the center timing of the received symbol input from the receiving filter 22, and selects and outputs only the sample at the center timing to generate a clock-recovered received symbol (step S13). The carrier recovery unit 24 corrects the frequency error and recovers the symbol phase of the clock-recovered received symbol input from the clock recovery unit 23, for example, using a method such as the Costas Loop method, and generates a carrier-recovered received symbol (step S14). At this time, for example, if the PSK-modulated symbol output from the modulation unit 13 is a BPSK-modulated symbol, the symbol phase is recovered as a QPSK-modulated symbol.

[0049] The UW bit hard decision unit 251 of the frame detection unit 25 performs hard decision on the carrier recovered symbol including the unique word by determining the quadrant of the carrier recovered received symbol (step S15). In the example of Fig. 5, the UW bit hard decision value obtained by performing hard decision on the 10 carrier recovered symbols is "0011010100" from the left in the figure.

[0050] As shown in FIG. 6, the shift register 252 stores the UW bit hard decision value corresponding to the number of bits of the unique word among the UW bit hard decision values ​​input from the UW bit hard decision unit 251 (step S16). The error bit number calculation unit 254 calculates the number of error bits by comparing the UW bit hard decision value stored in the shift register 252 with the unique word and counting the number of different bits (step S17). In the example of FIG. 5, the UW bit hard decision value of the first 6 bits of the symbol after carrier recovery is "001101", and the number of error bits is 3 compared with the unique word "110101". The UW bit hard decision value of the next 6 bits is "011010", and the number of error bits is 5 compared with the unique word "110101". The UW bit hard decision value of the next 6 bits is "110101", and the number of error bits is 0 compared with the unique word "110101".

[0051] As shown in FIG. 6, the allowable error bit number comparator 255 compares the number of error bits input from the error bit number calculator 254 with the allowable error bit number, which is a predetermined threshold value. The allowable error bit number comparator 255 determines that the bit string of the UW bit hard decision value stored in the shift register 252 is a unique word based on the comparison result between the number of error bits and the allowable error bit number, and detects the phase shift section (step S18). The allowable error bit number comparator 255 outputs the subframe timing at the timing when the phase shift section is detected (step S19). In the example of FIG. 5, if the allowable error bit number is 0, the allowable error bit number comparator 255 determines that the bit string of the 6-bit UW bit hard decision value, which has 0 error bit number compared with the unique word "110101", is a unique word, and detects the phase shift section.

[0052] 6, the symbol delay unit 26 delays the carrier-recovery received symbol input from the carrier recovery unit 24 by the number of bits of the unique word to generate a delay-adjusted received symbol (step S20). By delaying the carrier-recovery received symbol by the number of bits of the unique word in step S20, the start of the phase shift section of the delay-adjusted received symbol coincides with the subframe timing output by the frame detection unit 25.

[0053] The phase inverse shift unit 28 identifies a phase shift section for the delay-adjusted received symbol input from the symbol delay unit 26 based on the subframe timing input from the frame detection unit 25, and performs phase inverse rotation on the symbols in the phase shift section based on the unique word so as to cancel out the phase shift performed by the phase shift unit 15 of the transmitter 1, thereby generating a phase-inverse-shifted received symbol (step S21).

[0054] The demodulator 29 demodulates the phase-reverse-shifted received symbol input from the phase reverse shifter 28 to generate demodulated bits (step S22). The frame separator 30 separates the demodulated bits generated by the demodulator 29 into subframe units based on the subframe timing generated by the frame detector 25 to obtain received subframes (step S23). The received data separator 31 restores the transmission data from the received subframes generated by the frame separator 30. (step S24) If a transmission analog baseband signal is being received (step S25; YES), the process returns to step S11, and steps S11 to S24 are repeated. If a transmission analog baseband signal is no longer being received (step S25; NO), the process ends.

[0055] As described above, according to the first embodiment, a phase shift section of a modulated received symbol that has been phase-rotated by a predetermined amount of phase rotation based on a unique word is detected, and the modulated received symbol in the phase shift section identified based on the subframe timing output at the detected timing is phase-rotated so as to cancel out the predetermined amount of phase rotation, and then demodulated, thereby making it possible to realize wireless communication in which the transmission speed of information bits is not reduced and the SNR vs. BER performance for information bits is not deteriorated.

[0056] (Embodiment 2) In the first embodiment, the frame detection unit 25 performs hard decision based on the deflection angle of the received symbol after carrier recovery for the received symbol after carrier recovery including the unique word input from the carrier recovery unit 24. In the second embodiment, the frame detection unit 25 performs soft decision based on the deflection angle of the received symbol after carrier recovery for the received symbol after carrier recovery including the unique word input from the carrier recovery unit 24. In other words, the frame detection unit 25 determines the quadrant of the symbol point of the received symbol after carrier recovery.

[0057] The configuration of the frame detection unit 25 according to the second embodiment will be described with reference to Fig. 7. The frame detection unit 25 includes a UW bit soft decision unit 256 that performs soft decision on the received symbol after carrier recovery including the unique word, a shift register 252 that stores an LLR (Log Likelihood Ratio) that is a log likelihood ratio, a unique word output unit 253 that outputs a known unique word to a cross-correlation calculation unit 257 that calculates an absolute value of the cross-correlation between the input unique word and the LLR, and an absolute value comparison unit 258 that detects a phase shift section by determining whether the absolute value of the cross-correlation is equal to or greater than a predetermined threshold value. Other functional configurations of the receiver 2 are the same as those of the first embodiment. Here, the LLR is also called a UW bit soft decision value.

[0058] The process performed by the frame detection unit 25 will be described with reference to Fig. 8 and Fig. 9. As shown in Fig. 8, the UW bit soft decision unit 256 performs soft decision by calculating the LLR by quadrant decision for the received symbol after carrier recovery. Generally, for ease of implementation, the LLR is calculated by an approximation calculation shown in Fig. 9. As shown in Fig. 9, LLR=d0 2 -d1 2 where d0 is the minimum distance between a symbol point after carrier recovery arranged on the IQ plane and an ideal symbol point where the UW bit soft decision value is 0. d1 is the minimum distance between a received symbol point after carrier recovery arranged on the IQ plane and an ideal symbol point where the UW bit soft decision value is 1.

[0059] 8, the LLRs obtained by performing quadrant decision on 10 received symbols after carrier recovery are, from the left in the figure, "-0.91, -0.89, 0.91, 0.73, -0.90, 0.85, -0.88, 0.88, -0.75, -0.69." The shift register 252 stores, of the LLRs input from the UW bit soft decision unit 256, an LLR that corresponds to the number of bits of the unique word.

[0060] When the unique word output from the unique word output unit 253 is 6 bits "110101", the LLR equivalent to 6 bits is stored in the shift register 252. The cross-correlation calculation unit 257 compares the LLR equivalent to 6 bits stored in the shift register 252 with the bits of the unique word, and calculates the cross-correlation as 1 if the k-th bit value of the unique word is "1" and as -1 if the bit value is "0". The cross-correlation calculation unit 257 also calculates the absolute value of the cross-correlation. For example, the absolute value of the cross-correlation between the LLR of the first 6 bits of the 10 carrier recovered symbols shown in FIG. 8 and the unique word "110101" is 0.23. The absolute value of the cross-correlation between the LLR of the next 6 bits and the unique word "110101" is 3.34. The absolute value of the cross-correlation between the LLR of the next 6 bits and the unique word "110101" is 5.15.

[0061] The absolute value comparator 258 detects a phase shift section by comparing the absolute value of the cross-correlation input from the cross-correlation calculator 257 with a predetermined threshold, and outputs the subframe timing at the detected timing to the phase inverse shifter 28 and the frame separator 30. When the absolute value of the cross-correlation is equal to or greater than the predetermined threshold, the UW bit determination value is not determined to be a unique word, and this is an example of detecting a phase shift section, which is a predetermined section in which the phase is rotated, for modulated reception symbols phase-rotated by a predetermined amount of phase rotation in a predetermined section of each of a plurality of subframes.

[0062] In the example of FIG. 8, when the threshold value is set to 5 or more, the absolute value comparison unit 258 determines that a bit string of six LLRs having an absolute value of 5.15 of cross-correlation with the unique word “110101” is a unique word, and detects a phase shift section.

[0063] As described above, according to the second embodiment, the phase shift section of the modulated reception symbol that has been phase-rotated by a predetermined phase rotation amount based on the unique word is detected, and the modulated reception symbol in the phase shift section identified based on the subframe timing output at the detected timing is phase-rotated so as to cancel the predetermined phase rotation amount, and then demodulated, thereby realizing wireless communication without decreasing the transmission speed of information bits and without deteriorating the SNR vs. BER performance for information bits. In addition, since the UW bit soft decision unit 256 performs soft decision on the quadrant of the modulated reception symbol point that is the symbol point of the modulated reception symbol, the decoding success rate is higher than when the UW bit hard decision unit 251 performs hard decision on the quadrant of the modulated reception symbol point.

[0064] In the above embodiment, the receiver 2 includes the symbol delay unit 26, but the present disclosure is not limited to this. For example, when subframes are transmitted continuously, the receiver 2 does not need to include the symbol delay unit 26. In this case, it is sufficient to rotate the phase so as to cancel a predetermined phase rotation amount for the modulated reception symbol in the phase shift section in the subframe next to the subframe in which the phase shift section is detected.

[0065] Although the preferred embodiments have been described in detail above, the present invention is not limited to the above-described embodiments, and various modifications and substitutions can be made to the above-described embodiments without departing from the scope of the claims.

[0066] Various aspects of the present disclosure are summarized below as appendices.

[0067] (Appendix 1) A receiver that receives a transmission high-frequency signal generated by phase shift keying transmission data divided into a plurality of subframes, and reproduces the signal as a modulated reception symbol, comprising: a frame detection unit that detects a phase shift section, which is the predetermined section, of the modulated reception symbol that has been phase-rotated by a predetermined amount of phase rotation in each of the predetermined sections of the plurality of subframes; a phase inverse shift unit that rotates the phase of the modulated reception symbol in the detected phase shift section so as to cancel the predetermined phase rotation amount, thereby generating a phase inverse-shifted reception symbol; a demodulation unit that demodulates the phase-reverse-shifted received symbols to restore the transmission data; Equipped with A receiver, wherein the predetermined amount of phase rotation of the modulated received symbol is determined based on a unique word, which is a predetermined bit string that identifies a starting position of each of the plurality of subframes. (Appendix 2) The frame detection unit a UW bit determination value is calculated by determining a quadrant of a modulated reception symbol point, which is a symbol point of the modulated reception symbol arranged on an IQ plane, and the phase shift section is detected by comparing the UW bit determination value with the unique word, which is the predetermined bit string. 2. A receiver as defined in claim 1. (Appendix 3) The frame detection unit a UW bit hard decision unit that performs hard decision on the modulated reception symbol points arranged on the IQ plane as a binary value of 0 or 1 using a threshold value for the argument of the modulated reception symbol point, and outputs the result of the hard decision as the UW bit decision value; an error bit number calculation unit that compares the bit value of the unique word with the UW bit judgment value corresponding to the number of bits of the unique word, and calculates the total number of different bit values ​​as the number of error bits; an allowable error bit number comparison unit that determines whether the number of error bits exceeds an allowable error bit number, which is a tolerable number of error bits; 3. The receiver of claim 2, comprising: (Appendix 4) The number of modulation levels when the transmission data is phase shift modulated is M (M=2 1 , 2 2 , , 2 n : n is a natural number), and if the modulation multi-level number of the modulated received symbol is 2M, The UW bit hard decision unit is When the deflection angle θ of the modulated reception symbol point is (2m-1)π / 2M<|θ|≦(2m+1)π / 2M (m=1, 2, . . . , 2M / 2-1), the UW bit decision value is decided to be 1, and when the deflection angle θ of the modulated reception symbol point is other than (2m-1)π / 2M<|θ|≦(2m+1)π / 2M, the UW bit decision value is decided to be 0. 7. A receiver as described in claim 3. (Appendix 5) The allowable error bit number comparison unit When the number of error bits satisfies either one of the conditions that the number of error bits is equal to or less than the number of allowable error bits, or the number of error bits is equal to or greater than the value obtained by subtracting the number of allowable error bits from the number of bits of the unique word, the UW bit judgment value is judged to be the unique word. 5. A receiver as defined in claim 3 or 4. (Appendix 6) The frame detection unit a UW bit soft decision unit that calculates a log likelihood ratio of the modulated reception symbol point arranged on the IQ plane or an approximation value of the log likelihood ratio of the modulated reception symbol point as the UW bit decision value; a cross-correlation calculation unit that calculates an absolute value of cross-correlation between the unique word and the UW bit determination value corresponding to the number of bits of the unique word; an absolute value comparison unit that determines that the UW bit determination value is the unique word when the absolute value of the cross-correlation is equal to or greater than a predetermined threshold value; 3. The receiver of claim 2, comprising: (Appendix 7) a symbol delay unit that delays the modulated received symbol by the number of bits of the unique word to generate a delay-adjusted received symbol; the phase reverse shift unit specifies the phase shift section based on the timing at which the UW bit determination value is determined to be the unique word, rotates the phase of the delay-adjusted received symbol in the phase shift section so as to cancel the predetermined phase rotation amount determined based on the unique word, and generates a phase-reverse-shifted received symbol. 7. A receiver according to any one of claims 2 to 6. (Appendix 8) The number of modulation levels when the transmission data is phase shift modulated is M (M=2 1 , 2 2 , , 2 n : n is a natural number), the predetermined phase rotation amount of the modulated received symbol is π / M when the bit value of the unique word is 1, and is 0 when the bit value of the unique word is 0. 8. A receiver as claimed in any one of claims 1 to 7. (Appendix 9) a mapping rule for symbols when phase shift keying the transmission data is performed in accordance with a Gray code, and a mapping rule for the modulated reception symbols phase-rotated by the predetermined phase rotation amount is not in accordance with the Gray code; 9. A receiver according to any one of claims 1 to 8. (Appendix 10) The phase shift section of the subframe is a partial section of the subframe. 10. A receiver as claimed in any one of claims 1 to 9. (Appendix 11) The phase shift interval of the subframe is the entire interval of the subframe. 10. A receiver as claimed in any one of claims 1 to 9. (Appendix 12) A unique word output unit that outputs the unique word, The predetermined amount of phase rotation of the modulated received symbol is determined according to a bit value of the unique word output from the unique word output unit. 12. A receiver according to any one of claims 1 to 11. (Appendix 13) a receiving unit that receives the transmission high frequency signal, converts the signal into a baseband band that is a frequency band lower than the frequency band of the transmission high frequency signal, and digitally converts the signal, thereby generating reception symbols by band-limiting the signal; a clock recovery unit that estimates a center timing of the received symbol and selects and outputs only samples at the center timing to generate a received symbol after clock recovery; a carrier recovery unit that performs frequency error correction and symbol phase recovery on the received symbol after the clock recovery, and generates the modulated received symbol; 13. The receiver of any one of claims 1 to 12, further comprising: (Appendix 14) A wireless communication system having a transmitter that converts transmission symbols generated by phase shift keying of transmission data divided into a plurality of subframes into a transmission high-frequency signal and transmits the signal, and a receiver that receives the transmission high-frequency signal, reproduces the signal as modulated reception symbols, and demodulates the modulated reception symbols to restore the transmission data, The transmitter includes: a modulation unit that performs phase shift keying on the transmission data divided into the plurality of subframes to generate phase shift keying symbols; a phase shift unit that rotates the phase shift keying symbols by a predetermined phase rotation amount in a predetermined section of each of the plurality of subframes to generate the transmission symbols; Equipped with The receiver includes: a frame detection unit that detects a phase shift section, which is the predetermined section in which the modulated received symbol is phase-rotated by the predetermined phase rotation amount; a phase inverse shift unit that rotates the phase of the modulated reception symbol in the detected phase shift section so as to cancel the predetermined phase rotation amount, thereby generating a phase inverse-shifted reception symbol; a demodulation unit that demodulates the phase-reverse-shifted received symbols to restore the transmission data; Equipped with A wireless communication system, wherein the predetermined amount of phase rotation of the transmission symbol is determined based on a unique word, which is a bit string known to both the transmitter and the receiver, that identifies the starting position of each of the multiple subframes. (Appendix 15) A wireless reception method for receiving a transmission high-frequency signal generated by phase shift keying transmission data divided into a plurality of subframes, and reproducing the signal as a modulated reception symbol, comprising the steps of: Detecting a phase shift section, which is the predetermined section, in which the phase is rotated for the modulated reception symbol that has been phase-rotated by a predetermined amount of phase rotation in a predetermined section of each of the plurality of subframes; performing a phase rotation on the modulated reception symbol in the detected phase shift section so as to cancel the predetermined phase rotation amount, thereby generating a reception symbol after a reverse phase shift; demodulating the phase-shifted received symbols to recover the transmitted data; the predetermined phase rotation amount of the modulated received symbol is determined based on a unique word that is a predetermined bit string that identifies a start position of each of the plurality of subframes. Radio reception method. [Explanation of symbols]

[0068] 1 transmitter, 2 receiver, 11 transmission data generation unit, 12 frame generation unit, 13 modulation unit, 14 unique word output unit, 15 phase shift unit, 16 transmission filter, 17 DAC, 21 ADC, 22 reception filter, 23 clock recovery unit, 24 carrier recovery unit, 25 frame detection unit, 26 symbol delay unit, 27 unique word output unit, 28 phase inverse shift unit, 29 demodulation unit, 30 frame separation unit, 31 reception data separation unit, 100 wireless communication system, 251 UW bit hard decision unit, 252 shift register, 253 unique word output unit, 254 error bit number calculation unit, 255 allowable error bit number comparison unit, 256 UW bit soft decision unit, 257 cross-correlation calculation unit, 258 absolute value comparison unit.

Claims

1. A receiver that receives a transmission high-frequency signal generated by phase shift keying transmission data divided into a plurality of subframes, and reproduces the signal as a modulated reception symbol, comprising: a frame detection unit that detects a phase shift section, which is the predetermined section, of the modulated reception symbol that has been phase-rotated by a predetermined amount of phase rotation in each of the predetermined sections of the plurality of subframes; a phase inverse shift unit that rotates the phase of the modulated reception symbol in the detected phase shift section so as to cancel the predetermined phase rotation amount, thereby generating a phase inverse-shifted reception symbol; a demodulation unit that demodulates the phase-reverse-shifted received symbols to restore the transmission data; Equipped with A receiver, wherein the predetermined amount of phase rotation of the modulated received symbol is determined based on a unique word, which is a predetermined bit string that identifies a starting position of each of the plurality of subframes.

2. The frame detection unit a UW bit determination value is calculated by determining a quadrant of a modulated reception symbol point, which is a symbol point of the modulated reception symbol arranged on an IQ plane, and the phase shift section is detected by comparing the UW bit determination value with the unique word, which is the predetermined bit string; 2. The receiver of claim 1.

3. The frame detection unit a UW bit hard decision unit that performs hard decision on the modulated reception symbol points arranged on the IQ plane as a binary value of 0 or 1 using a threshold value for the argument of the modulated reception symbol point, and outputs the result of the hard decision as the UW bit decision value; an error bit number calculation unit that compares the bit value of the unique word with the UW bit judgment value corresponding to the number of bits of the unique word, and calculates the total number of different bit values ​​as the number of error bits; an allowable error bit number comparison unit that determines whether the number of error bits exceeds an allowable error bit number, which is a tolerable number of error bits; 3. The receiver of claim 2, comprising:

4. The number of modulation levels when the transmission data is phase shift modulated is M (M=2 １ , 2 ２ , ..., 2 ｎ : n is a natural number), and the modulation multi-level number of the modulated received symbol is 2M, The UW bit hard decision unit When the deflection angle θ of the modulated reception symbol point is (2m-1)π / 2M<|θ|≦(2m+1)π / 2M (m=1, 2, ..., 2M / 2-1), the UW bit judgment value is judged to be 1, and when the deflection angle θ of the modulated reception symbol point is other than (2m-1)π / 2M<|θ|≦(2m+1)π / 2M, the UW bit judgment value is judged to be 0.

4. The receiver according to claim 3.

5. The allowable error bit number comparison unit When the number of error bits satisfies either one of the conditions that the number of error bits is equal to or less than the number of allowable error bits, or the number of error bits is equal to or greater than a value obtained by subtracting the number of allowable error bits from the number of bits of the unique word, the UW bit judgment value is judged to be the unique word.

4. The receiver according to claim 3.

6. The frame detection unit a UW bit soft decision unit that calculates a log likelihood ratio of the modulated reception symbol point arranged on the IQ plane or an approximation value of the log likelihood ratio of the modulated reception symbol point as the UW bit decision value; a cross-correlation calculation unit that calculates an absolute value of cross-correlation between the unique word and the UW bit determination value corresponding to the number of bits of the unique word; an absolute value comparison unit that determines that the UW bit determination value is the unique word when the absolute value of the cross-correlation is equal to or greater than a predetermined threshold value; 3. The receiver of claim 2, comprising:

7. a symbol delay unit that delays the modulated received symbol by the number of bits of the unique word to generate a delay-adjusted received symbol; the phase reverse shift unit specifies the phase shift section based on a timing at which the UW bit determination value is determined to be the unique word, rotates a phase of the delay-adjusted received symbol in the phase shift section so as to cancel the predetermined phase rotation amount determined based on the unique word, and generates a phase-reverse-shifted received symbol.

7. A receiver according to any one of claims 2 to 6.

8. The number of modulation levels when the transmission data is phase shift modulated is M (M=2 １ , 2 ２ , ..., 2 ｎ : n is a natural number), the predetermined phase rotation amount of the modulated received symbol is π / M when the bit value of the unique word is 1, and is 0 when the bit value of the unique word is 0.

7. A receiver according to any one of claims 1 to 6.

9. a mapping rule for symbols when phase shift keying the transmission data is performed in accordance with a Gray code, and a mapping rule for the modulated reception symbols phase-rotated by the predetermined phase rotation amount is not in accordance with the Gray code; 7. A receiver according to any one of claims 1 to 6.

10. The phase shift section of the subframe is a partial section of the subframe.

7. A receiver according to any one of claims 1 to 6.

11. The phase shift interval of the subframe is the entire interval of the subframe.

7. A receiver according to any one of claims 1 to 6.

12. A unique word output unit that outputs the unique word, The predetermined amount of phase rotation of the modulated received symbol is determined according to a bit value of the unique word output from the unique word output unit.

7. A receiver according to any one of claims 1 to 6.

13. a receiving unit that receives the transmission high frequency signal, converts the signal into a baseband band that is a frequency band lower than the frequency band of the transmission high frequency signal, and digitally converts the signal, thereby generating reception symbols by band-limiting the signal; a clock recovery unit that estimates a center timing of the received symbol and selects and outputs only samples at the center timing to generate a received symbol after clock recovery; a carrier recovery unit that performs frequency error correction and symbol phase recovery on the received symbol after the clock recovery, and generates the modulated received symbol; 7. The receiver of claim 1, further comprising:

14. A wireless communication system having a transmitter that converts transmission symbols generated by phase shift keying of transmission data divided into a plurality of subframes into a transmission high-frequency signal and transmits the signal, and a receiver that receives the transmission high-frequency signal, reproduces the signal as modulated reception symbols, and demodulates the modulated reception symbols to restore the transmission data, The transmitter includes: a modulation unit that performs phase shift keying on the transmission data divided into the plurality of subframes to generate phase shift keying symbols; a phase shift unit that rotates the phase shift keying symbols by a predetermined phase rotation amount in a predetermined section of each of the plurality of subframes to generate the transmission symbols; Equipped with The receiver includes: a frame detection unit that detects a phase shift section, which is the predetermined section in which the modulated received symbol is phase-rotated by the predetermined phase rotation amount; a phase inverse shift unit that rotates the phase of the modulated reception symbol in the detected phase shift section so as to cancel the predetermined phase rotation amount, thereby generating a phase inverse-shifted reception symbol; a demodulation unit that demodulates the phase-reverse-shifted received symbols to restore the transmission data; Equipped with A wireless communication system, wherein the predetermined amount of phase rotation of the transmission symbol is determined based on a unique word known to both the transmitter and the receiver that identifies the starting position of each of the plurality of subframes.

15. A wireless reception method for receiving a transmission high-frequency signal generated by phase shift keying transmission data divided into a plurality of subframes, and reproducing the signal as a modulated reception symbol, comprising the steps of: Detecting a phase shift section, which is the predetermined section, in which the phase is rotated for the modulated reception symbol that has been phase-rotated by a predetermined amount of phase rotation in a predetermined section of each of the plurality of subframes; performing a phase rotation on the modulated reception symbol in the detected phase shift section so as to cancel the predetermined phase rotation amount, thereby generating a reception symbol after a reverse phase shift; demodulating the phase-shifted received symbols to recover the transmitted data; the predetermined phase rotation amount of the modulated received symbol is determined based on a unique word that is a predetermined bit string that identifies a start position of each of the plurality of subframes. Radio reception method.

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