JP2008072625A - Reception apparatus and reception method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a reception apparatus and reception method for easily and accurately establishing timing synchronization based on a reception signal with simple configuration. <P>SOLUTION: The reception apparatus comprises: a signal receiving unit 21 in which when a transmission side performs signal transmission while including a preamble containing a first symbol constituted of a plurality of frames indicative of "0", "+1" or "-1" and a second symbol in which "0" in a frame stream constituting the first symbol is set to "+1" or "-1" and "+1" or "-1" is set to "0", a signal containing the preamble is received; and a demodulation unit 22 which squares the received signal, then operates a correlation between the squared received signal and a template which is held so that a correlation value with one of squared received signals corresponding to the first or the second symbol becomes a plus value and a correlation value with the other becomes a minus value, and establishes timing synchronization based on a correlation value as an arithmetic result. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a receiving apparatus and a receiving method for establishing timing synchronization by demodulating a received signal by asynchronous detection in impulse transmission wireless communication using a wide band.

  In recent years, in the field of wireless communication, attention has been paid to a communication system using UWB (Ultra Wide Band) as a technique for realizing a high transmission rate. UWB performs wireless communication using a wide bandwidth of 500 MHz or more, and has features such as low power consumption and extremely high position detection (ranging) accuracy. Various technologies related to UWB have been proposed by IEEE (Institute of Electrical and Electronics Engineers) 802.15.3a, IEEE 802.15.4a, and the like.

  In a communication system using UWB, it is necessary to establish timing synchronization between a data transmission side device (transmission device) and a data reception side device (reception device). Specifically, as a signal for the transmission apparatus to establish timing synchronization, for example, a preamble sequence is included in the transmission signal and transmitted, and the reception apparatus calculates a correlation between the reception signal and a predetermined template (known sequence). Timing synchronization is taken based on the correlation value obtained as the calculation result.

  In such a communication system using UWB, it is easy to determine whether or not there is a specific correlation between the received signal and the template in order to establish accurate timing synchronization between the transmitting device and the receiving device. It is desired to make an accurate determination based on the device configuration.

  For example, in the communication method described in Patent Document 1, the transmission side assigns “1” and “0” signals to analog polarity (biphase waveform), and the reception side has a correlation between the received signal and the template. These determinations are made by analog signals.

Special Table 2003-535552

  However, in the above conventional technique, accurate correlation values cannot be obtained in the correlation calculation between the received signal and the template due to variations in the analog signal, and the correlation determination accuracy deteriorates accordingly. There was a problem that it was difficult to establish well. Further, since the correlation is determined based on the result of the correlation calculation using the analog signal, there is a problem that the analog circuit becomes complicated and the cost of the communication system increases.

  The present invention has been made in view of the above, and provides a receiving apparatus and a receiving method for easily and accurately establishing timing synchronization based on a received signal in a wireless communication using a wide bandwidth with a simple configuration. With the goal.

  In order to solve the above-described problems and achieve the object, the present invention is a reception apparatus that receives a transmission signal including a preamble and establishes timing synchronization using the preamble in the reception signal. The first symbol composed of a plurality of frames each indicating “0”, “+1”, or “−1”, and “0” in the frame sequence constituting the first symbol are changed to “+1” or “ In the case of generating a preamble including the second symbol set to “−1” and “+1” or “−1” set to “0” and performing signal transmission including the preamble, the preamble is A reception unit that receives the included signal and executes a predetermined reception process; a signal output from the reception unit is squared; then, the squared reception signal and 2 corresponding to the first symbol Squared The correlation value with one of the received signal or the squared received signal corresponding to the second symbol is a positive value and the correlation value with the other is held in advance so as to be a negative value. A demodulator that calculates a correlation with the template and establishes timing synchronization based on a correlation value obtained as a result of the calculation.

  According to the present invention, since the correlation value between the preamble signal and the template shows a negative value and a positive value, edge detection using a positive value and a negative value obtained by the correlation calculation between the preamble signal and the template. As a result, the timing synchronization can be easily and accurately established with a simple configuration.

  Embodiments of a receiving apparatus and a receiving method according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. Below, the characteristics and outline of the receiving device and the receiving method, the device configuration of the transmitting device and the receiving device, the configuration of frames transmitted and received between the transmitting device and the receiving device, the processing procedure of the transmitting device and the receiving device (establish timing synchronization Will be described in the order of processing procedure (demodulation processing procedure by asynchronous detection), and finally, other embodiments (Embodiments 2 to 4) will be described as modified examples.

Embodiment 1 FIG.
(Overview and features)
First, the concept of how to synchronize the timing of the receiving apparatus according to the first embodiment will be described. In the first embodiment, the transmission apparatus encodes data corresponding to “0” of pre-encoding data as a signal (frame) for establishing timing synchronization such as a preamble (for example, IEEE 802.15.4a preamble). A subsequent signal (a symbol “S” described later) and an encoded signal (a symbol “−S” described later) corresponding to “1” of the pre-encoding data are transmitted. The receiving apparatus performs asynchronous detection (demodulation) on the received signal in order to establish timing synchronization using the preamble included in the received signal.

  In the present embodiment, when the transmission apparatus performs encoding, the encoded data is generated so that the polarity of the encoded data is inverted between “0” and “1” of the encoded data. . Specifically, when the encoded data corresponding to “0” of the pre-encoding data is “111100010011010”, for example, the encoded data corresponding to “1” of the pre-encoding data is “000011101100101”. To. That is, the symbol “-S” sequence has a relationship in which “0” and “1” are interchanged with respect to the symbol “S” sequence.

  In the receiving apparatus, when performing asynchronous detection, the received signal is squared, and then the correlation between the squared received signal and a template that is a known sequence in advance (hereinafter referred to as a correlation comparison template). And the correlation between the received signal and the correlation comparison template is determined based on the correlation value obtained by this calculation.

  The correlation comparison template here is a series in which the correlation calculation result with the symbol “S” has a positive value and the correlation calculation result with the symbol “−S” has a negative value. In the present embodiment, the concept of phase shift keying (PSK) is introduced to determine the correlation between the received signal and the correlation comparison template. In the receiving apparatus, the correlation between the received signal and the correlation comparison template is introduced. When determining the relationship, the correlation is determined using a correlation value indicating a negative value and a correlation value indicating a positive value. Thereby, in this embodiment, when establishing timing synchronization, it is possible to establish synchronization with high accuracy by edge detection using a positive correlation value and a negative correlation value.

(Device configuration)
Next, configurations of the transmission device and the reception device according to the first exemplary embodiment of the present invention will be described. FIG. 1 is a functional block diagram showing the configuration of the transmitting apparatus according to the first embodiment of the present invention, and FIG. 2 is a functional block diagram showing the configuration of the receiving apparatus according to the first embodiment of the present invention.

  The transmission device 1 in FIG. 1 and the reception device 2 in FIG. 2 are communication devices (broadband wireless devices) that perform impulse wireless communication using UWB, and various signals (data) are transmitted from the transmission device 1 to the reception device 2. Impulse transmission.

  The transmission device 1 includes a signal generation unit 11 that generates transmission data, a signal transmission unit 12 that transmits transmission data generated by the signal generation unit 11 to the reception device 2 via the antenna 37, the signal generation unit 11, and the signal And a control unit 13 that controls the transmission unit 12.

  In the transmission device 1, for example, the signal generation unit 11 generates a preamble (symbol “S”, symbol “−S”, etc.) for timing synchronization (chip synchronization, frame synchronization, symbol synchronization), and the preamble is generated. The included transmission data is transferred to the signal transmission unit 12, and the signal transmission unit 12 performs a predetermined transmission process on the transmission data, and transmits the resulting signal via the antenna 37.

  The receiving device 2 receives a signal transmitted from the transmitting device 1 via the antenna 41, and performs asynchronous detection (incoherent detection) on the signal received by the signal receiving unit 21. The demodulator 22 includes a signal receiver 21 and a controller 23 that controls the demodulator 22.

  In the receiving device 2, for example, the signal receiving unit 21 receives a signal transmitted from the transmitting device 1 via the antenna 41, and the demodulating unit 22 performs asynchronous detection (demodulation) on the received signal. Establish timing synchronization and generate demodulated data.

  Here, the circuit configuration of the transmission apparatus 1 shown in FIG. 1 and the circuit configuration of the reception apparatus 2 shown in FIG. 2 will be described. FIG. 3 is a circuit block diagram illustrating a circuit configuration of the transmission apparatus. As shown in FIG. 3, the transmission device 1 includes a FRAMER 31, a MOD (MODulator) 32, a DAC (D / A Converter) 33, an LPF (Low Pass Filter) 34, a Mixer 35, and a BPF (Band Pass Filter). 36, an antenna 37, and a LOCAL 38.

  The FRAMER 31 is a block for constructing a frame for transmission in a wireless section, such as addition of a preamble or addition of control information, to the information bit sequence input to the transmission apparatus 1. The FRAMER 31 is connected to the MOD 32 and inputs the bit sequence generated here to the MOD 32.

  The MOD 32 is a block that encodes and modulates the signal input from the FRAMER 31. The MOD 32 is connected to the DAC 33, and the modulation signal (digital signal) generated here is input to the DAC 33. In the present embodiment, the MOD 32 generates a symbol (sequence of encoded data) such that the polarity is inverted between “0” and “1” of the pre-encoding data.

  The DAC 33 is a block that converts the digital signal input from the MOD 32 into an analog signal. The DAC 33 is connected to the LPF 34, and the analog signal converted here is input to the LPF 34.

  The LPF 34 is a block that performs processing for attenuating the aliasing component and the harmonic component with respect to the analog signal input from the DAC 33. The LPF 34 is connected to the Mixer 35, and inputs the signal passed here to the Mixer 35.

  The LOCAL 38 is a block for generating a center frequency used for signal transmission. The LOCAL 38 is connected to the Mixer 35, and inputs the generated center frequency signal to the Mixer 35.

  The Mixer 35 is a block that converts the frequency of the signal input from the LPF 34 to a high frequency using the center frequency generated by the LOCAL 38. The Mixer 35 is connected to the BPF 36 and inputs the converted signal to the BPF 36.

  The BPF 36 is a block that removes frequencies other than those used for signal transmission from the signal input from the Mixer 35. The BPF 36 is connected to the antenna 37, and transmits the signal that has passed through the antenna 37 via the antenna 37.

  Here, FRAMER 31, MOD 32, and DAC 33 correspond to the signal generation unit 11 shown in FIG. 1, and LPF 34, Mixer 35, BPF 36, and LOCAL 38 here correspond to the signal transmission unit 12 shown in FIG.

  In FIG. 3, various signals (signal flows) processed in the transmission apparatus 1 are indicated by signals s1 to s8. The signal s1 is an information bit sequence input to the transmission apparatus 1, and the signal s2 is a bit sequence in which a preamble and control information for frame synchronization and timing synchronization are added to the information bit sequence of the signal s1. The signal s3 is a digital signal after the signal s2 is modulated and encoded, and the signal s4 is a signal obtained by converting the signal s3 into analog.

  The signal s5 is a signal obtained by attenuating an unnecessary signal outside the band from the signal s4, and the signal s6 is a signal obtained by shifting the center frequency of the signal s5 to a high frequency. Furthermore, the signal s7 is a signal obtained by attenuating an unnecessary signal outside the band from the signal s6, and the signal s8 is a signal indicating a center frequency used for signal transmission.

  Next, the circuit configuration of the receiving device 2 shown in FIG. 2 will be described. FIG. 4 is a circuit block diagram illustrating a circuit configuration of the receiving device. As shown in FIG. 4, the receiving apparatus 2 includes an antenna 41, a BPF 42, an LNA (Low Noise Amplifier) 43, a Mixer 44, an LPF 45, an amplitude power conversion block 46, an integration circuit 47, an ADC (A / A). D Converter) 48, DEM (DEModulator) 49, LOCAL 50, and SYNC 51.

  The antenna 41 receives a band signal (signal from the transmission device 1) used in wireless communication. The antenna 41 is connected to the BPF 42 and inputs a received signal to the BPF 42. The BPF 42 is a block that removes frequencies other than those used for signal processing (timing synchronization, etc.) from the signal received by the antenna 41. The BPF 42 is connected to the LNA 43 and inputs the signal that has passed here to the LNA 43.

  The LNA 43 is a block that performs amplification (amplification with a small noise figure) processing with low noise addition on the signal input from the BPF 42. The LNA 43 is connected to the mixer 44, and inputs the amplified signal to the mixer 44.

  The LOCAL 50 is a block that generates a center frequency used for signal processing. The LOCAL 50 is connected to the Mixer 44, and the center frequency signal generated here is input to the Mixer 44.

  The Mixer 44 is a block that converts the frequency of the signal input from the LNA 43 to the baseband using the center frequency generated by the LOCAL 50. The Mixer 44 is connected to the LPF 45 and inputs the signal converted here to the LPF 45.

  The LPF 45 is a block that performs processing for attenuating the harmonic component of the signal input from the mixer 44. The LPF 45 is connected to the amplitude power conversion block 46, and the signal passed here is input to the amplitude power conversion block 46.

  The amplitude power conversion block 46 is a block for performing an operation of converting the signal input from the LPF 45 into power. The amplitude power conversion block 46 is connected to the integration circuit 47, and the signal converted here is input to the integration circuit 47.

  The integration circuit 47 is a block that integrates a value for a predetermined time of the signal (power value) processed by the amplitude power conversion block 46. The integrating circuit 47 is connected to the ADC 48 and inputs the signal (analog signal) processed here to the ADC 48.

  The ADC 48 is a block that converts an analog signal input from the integration circuit 47 into a digital signal. The ADC 48 is connected to the DEM 49 and the SYNC 51, and inputs the converted signal to the DEM 49 and the SYNC 51.

  The SYNC 51 is connected to the DEM 49. The SYNC 51 is a block that performs timing synchronization, frequency synchronization establishment, signal level adjustment, and the like using signals input from the ADC 48 and the DEM 49. The signal generated by the SYNC 51 is input to the DEM 49.

  The DEM 49 is a block that performs demodulation processing and decoding processing of the signal input from the ADC 48 using the synchronization signal generated by the SYNC 51. The DEM 49 outputs the original transmission bit sequence as a demodulated signal.

  In this embodiment, the DEM 49 performs a correlation operation between the signal received from the ADC 48 and the correlation comparison template, and the SYNC 51 detects a specific correlation based on the obtained correlation value to establish timing synchronization. To do.

  The BPF 42, the LNA 43, the mixer 44, and the LPF 45 here correspond to the signal receiving unit 21 shown in FIG. 2, and the amplitude power conversion block 46, the integration circuit 47, the ADC (A / D Converter) 48, and the DEM here. (DEModulator) 49, LOCAL 50, and SYNC 51 correspond to the demodulator 22 shown in FIG.

  In FIG. 4, various signals (signal flows) processed in the receiving apparatus 2 are indicated by signals s21 to s31. The signal s21 is an analog RF (Radio Frequency) reception signal transmitted from the transmission device 1, and the signal s22 is a signal obtained by attenuating an unnecessary signal outside the band from the signal s21.

  The signal s23 is a signal obtained by amplifying the signal s22, the signal s30 is a signal indicating a center frequency used for signal processing, and the signal s24 is a signal obtained by multiplying the signal s23 and the signal s30 (number of centers frequency) ( Signal s23 is shifted to the center frequency). The signal s25 is a signal obtained by attenuating an unnecessary signal outside the band of the signal s24, and the signal s26 is a signal obtained by converting the amplitude information of the signal s25 into power information.

  The signal s27 is a signal obtained by integrating the time signal of the signal s26, and the signal s28 is a signal obtained by digitally converting the signal s27. Further, the signal s31 is a signal indicating timing synchronization information, and the signal s29 is a signal (received signal bit sequence signal) after the signal s28 is demodulated and decoded using the signal s31.

(Transmission frame configuration)
Next, a configuration of a frame transmitted / received between the transmission device 1 and the reception device 2 will be described. FIG. 5 is a diagram illustrating an example of a configuration of a signal transmitted from the transmission apparatus. A signal transmitted from the transmission apparatus 1 is composed of a preamble, a header, a payload, and the like. Among these, the preamble includes a synchronization field (SYNC) that is a synchronization field, a CE (Channel Estimation field) for measuring a signal propagation state, and an SFD (Start Frame Delimiter field) that is a frame start part. It consists of Each of SYNC, CE, and SFD has a plurality of symbols “S”.

  The SFD is configured by combining a symbol “S” (first symbol), a symbol “−S” (second symbol), and a symbol “0” (third symbol). The symbol “S” and the symbol “−S” indicate data of different polarities (encoded data). Here, the case where the symbol “S” corresponds to the pre-encoding data “0” and the symbol “−S” corresponds to the pre-encoding data “1” will be described. The symbol “S” used here is a sequence having excellent autocorrelation characteristics.

  The symbol “0” is a symbol other than the symbol “S” and the symbol “−S”. The symbol “0” is a correlation calculation between the received signal and the correlation comparison template in the receiving device 2, and is different from the symbol “S” and the symbol “−S” (the correlation value of the symbol “S” and the symbol “S”). -S "is a symbol indicating a correlation value (for example, cross-correlation value 0) .In this embodiment, the symbol" S "and the symbol" -S "are not used without using the symbol" 0 ". It is also possible to take timing synchronization only.

  FIG. 6 is a diagram for explaining the relationship between symbols and frames. One symbol is a data transmission unit, and a cycle in which one symbol is transmitted is a symbol cycle Ts. One symbol is composed of a plurality of frames (for example, 15 frames), and a cycle in which one frame is transmitted is a frame cycle Tf. For example, the transmitter 1 transmits 15 frames as one symbol, and the receiver 2 acquires 15 frames from the received 1 symbol.

  One frame is composed of a plurality of chips, and one chip has a chip cycle Tc. The chip cycle Tc (for example, 1 ns) is an operation cycle of the DAC 33 of the transmission device 1 and the ADC 48 of the reception device 2. Here, for example, a case where the 1 GHz band is used as the DAC 33 and the ADC 48 of 1 GHz sample will be described. In UWB, transmission power per unit time (for example, 1 ms) is limited. The symbol period Ts is, for example, 480 ns, and the frame period Tf is, for example, 32 ns.

  FIG. 7 is a diagram illustrating an example of a symbol configuration. In FIG. 7, the configuration of the symbol “S” is shown as an example of the configuration of the symbol. The symbol “S” is composed of, for example, 15 frames, and each frame (sequence) indicates one of “+1”, “0”, and “−1”.

  In the present embodiment, for convenience of explanation, an ideal transmission path (transmission signal = reception signal) is assumed in which the reception apparatus 2 can receive the signal transmitted by the transmission apparatus 1 without being affected by noise. To do.

  Further, in the present embodiment, when the transmitting apparatus 1 transmits the symbol “S”, the receiving apparatus 2 has excellent correlation characteristics on the plus side (the correlation obtained by the correlation calculation with the correlation comparison template is steep). In addition, when the transmission apparatus 1 transmits the symbol “-S”, an excellent correlation characteristic on the minus side is obtained in the reception apparatus 2, and when the transmission apparatus 1 transmits the symbol “0”. The cross-correlation value obtained in the receiving device 2 is 0.

  FIG. 8 is a diagram for explaining the configuration of each symbol type. In the present embodiment, when the correlation between the received signal and the template is performed, the symbol “S” (first symbol) is used so that the receiving apparatus 2 can obtain a positive value and a negative value as a cross-correlation value. Define the symbol “-S” (second symbol).

  Specifically, as shown in FIG. 7, the MOD 32 sets the frame set to “1” or “−1” in the symbol “S” to “0” in the symbol “−S”, while Thus, the frame set to “0” in the symbol “S” is set to “1” or “−1” in the symbol “-S”. Thereby, the relationship between the symbol “S” and the symbol “−S” is a relationship in which a frame indicating “+1” or “−1” and a frame indicating “0” are inverted between the symbols. .

  In the symbol “-S”, the frame “0” in the symbol “S” may be set to either the frame “1” or the frame “−1”. In addition, in the symbol “S”, only one of the frame “−1” or the frame “1” and the frame “0” may be set.

(Demodulation procedure by asynchronous detection)
Next, a processing procedure when the receiving device 2 takes timing synchronization will be described. Here, after describing the processing procedure in the transmission apparatus 1, the processing procedure in the reception apparatus 2 will be described.

  FIG. 9 is a flowchart of a process procedure performed by the transmission apparatus according to the first embodiment. In the transmission apparatus 1, the FRAMER 31 constructs a frame for transmission in a wireless section, such as addition of a preamble or addition of control information, to the information bit sequence (signal s1) input to the transmission apparatus 1 (step S10). ). The FRAMER 31 inputs a signal (bit sequence) after frame construction to the MOD 32 as a signal s2.

  The MOD 32 performs encoding and modulation on the signal s2 input from the FRAMER 31. Here, the encoding process performed by the MOD 32 of the transmission apparatus 1 will be described in detail. FIG. 10 is a diagram for explaining an example of encoding processing performed by MOD. In MOD32, a sequence having excellent correlation characteristics such as an M sequence is used for encoding. Here, a case is shown in which M sequence degree 4, feedback tap (1, 4), and initial value “1111” are used as conditions for setting a sequence of encoded data.

  The first point in the present embodiment is that the MOD 32 reverses the polarity of the encoded data between “0” and “1” of the pre-encoded data. Specifically, when the encoded data corresponding to “0” of the pre-encoding data is “111100010011010”, for example, the encoded data corresponding to “1” of the pre-encoding data is “000011101100101”. To.

  As described above, in MOD32, symbol “S” and symbol “−S” are generated by performing the encoding process so that the polarity is inverted between “0” and “1” of the pre-encoding data (step S20). . The encoded data only needs to be a sequence with excellent correlation characteristics, and encoding may be performed using a sequence other than the M sequence. The MOD 32 inputs the generated symbol to the DAC 33 as a signal s3.

  The DAC 33 converts the digital signal input from the MOD 32 into an analog signal. Here, the output waveform of the signal output from the DAC 33 of the transmission apparatus 1 will be described. FIG. 11 is a diagram illustrating an example of a transmission waveform of a signal output from the DAC. The DAC 33 outputs a signal in which ON (transmission) or OFF (non-transmission) is set at a predetermined chip cycle Tc for each frame cycle based on the encoded data (“0” or “1”). Output for. This makes it possible to place information at a desired position. In the present embodiment, the signal is set to ON when the value of the encoded data is “1”, and the signal is set to OFF when the value of the encoded data is “0”.

  The DAC 33 inputs the transmission waveform in which ON and OFF are set to the LPF 34 as a signal s4. The LPF 34 executes processing for attenuating the aliasing component and the harmonic component with respect to the signal s4, and inputs the processed signal to the mixer 35 as the signal s5. The Mixer 35 multiplies the center frequency generated by the LOCAL 38 and the signal s5 input from the LPF 34, and outputs a signal s6 as an RF signal.

  Here, the transmission waveform of the signal (signal s6) output from the Mixer 35 of the transmission apparatus 1 will be described. FIG. 12 is a diagram illustrating an example of a transmission waveform of a signal output from the mixer. The Mixer 35 RF-outputs the signal s6 with a signal waveform in which ON (transmission) and OFF (non-transmission) are set at a position corresponding to a specific chip time (step S30).

  The BPF 36 removes frequencies other than the frequency used for signal transmission from the signal s6 input from the Mixer 35. Then, the BPF 36 transmits the signal processed by the BPF 36 to the receiving device 2 via the antenna 37 (step S40).

  Next, a processing procedure in the receiving device 2 will be described. FIG. 13 is a flowchart of a process procedure performed by the receiving apparatus according to the first embodiment. The antenna 41 of the receiving device 2 receives the signal transmitted from the transmitting device 1 (step S110), and inputs it to the BPF 42 as the signal s21.

  Here, an ideal reception waveform of a signal received by the antenna 41 of the reception device 2 will be described. FIG. 14 is a diagram illustrating an example of a reception waveform of a signal received by the reception device. Assuming a transmission path in which no delay wave exists when there is no noise, the receiving device 2 receives a signal with the same signal waveform (the transmission waveform shown in FIG. 12) as the transmission waveform transmitted from the transmitting device 1. As a result, the receiving apparatus 2 can observe the transmission signal only during the time (chip period Tc) when the signal is output as the ideal transmission waveform.

  The BPF 42 removes a frequency other than the frequency used for signal processing (timing synchronization or the like) from the signal s21 received by the antenna 41, and inputs the signal to the LNA 43 as a signal s22.

  The LNA 43 performs amplification processing with low noise addition on the signal s22 and inputs the signal s23 to the mixer 44. The Mixer 44 converts the frequency of the signal s23 input from the LNA 43 into the baseband using the center frequency generated by the LOCAL 50, and inputs the signal to the LPF 45 as the signal s24. The LPF 45 performs a process of attenuating the harmonic component on the signal s24, and inputs the signal to the amplitude power conversion block 46 as the signal s25.

  The amplitude power conversion block 46 converts the signal s24 into electric power, and inputs the converted signal to the integration circuit 47 as the signal s26. The integration circuit 47 integrates the value of the signal s26 for a predetermined time, and inputs it to the ADC 48 as the signal s27. As a result, the received waveform received by the receiving apparatus 2 is converted into a predetermined power value (analog signal) by the amplitude power conversion block 46 and the integration circuit 47. The ADC 48 converts the signal s27 (analog signal) into a digital signal, and inputs it to the DEM 49 and the SYNC 51 as the signal s28.

  Here, the digital signal (signal s28) passing through the ADC 48 will be described. FIG. 15 is a diagram illustrating an example of a digital signal passing through the ADC. FIG. 15 shows a digital signal (ideal received ADC data) that has passed through the ADC 48 under ideal conditions (such as when there is no influence of noise). As for a signal passing through the ADC 48, only a signal whose power exceeds a predetermined threshold among signals (signal s27) input to the ADC 48 is output as “1”, and a signal whose power does not exceed the predetermined threshold is “0”. Is output. Here, in the transmission apparatus 1, “1” is output from the ADC 48 only at a location where ON is set (chip timing).

  The DEM 49 opens the time filter at a periodic timing (once every frame time), and determines whether the received frame is “1” or “0” at the timing when the time filter is opened. Specifically, the DEM 49 treats the frame as “1” if there is a chip “1” in the frame, and treats the frame as “0” if there is no chip “1” in the frame.

  Accordingly, the DEM 49 can determine whether the frame is “0” or “1” for each received frame, and acquire the received symbol sequence. FIG. 16 is a diagram for explaining the received signal after passing through the time filter.

  Here, a signal (symbol) after passing through an ideal time filter in consideration of transmission path conditions is shown. In the present embodiment, the positions of the frame “1” and the frame “0” constituting the sequence are determined depending on whether the encoded data transmitted by the transmission apparatus 1 is the symbol “S” or the symbol “−S”. Is reversed. For this reason, in the signal received by the receiving device 2, the encoded data when the pre-encoding data is “0” and the encoded data when the pre-encoding data is “1”, The positions of “0” and “1” in the received frame are reversed.

  The DEM 49 performs a correlation calculation between the signal (frame value) after passing through the time filter and the correlation comparison template, and determines the correlation between the received signal and the correlation comparison template.

  Here, the asynchronous detection processing of signals by the receiving device 2 will be described. FIG. 17 is a diagram for explaining the asynchronous detection processing of the receiving apparatus according to the first embodiment. In the present embodiment, the DEM 49 stores a correlation comparison template in advance. Then, the DEM 49 calculates the correlation with the received signal (symbol “S” or symbol “−S”) using the correlation comparison template.

In the present embodiment, the amplitude power conversion block 46 first calculates | r (t) ² | for the received signal r (t) (step S120). Then, the ADC 48 converts the analog signal integrated by the integration circuit 47 into a digital signal. As a result, the received signal | r (t) ² | of the symbol “S” or the symbol “−S” has a value indicated by only “0” and “1”.

  Next, the DEM 49 performs a correlation operation between the sequence set in the correlation comparison template and the output sequence of the ADC 48 (step S130). The DEM 49 sequentially calculates the correlation between the output sequence of the ADC 48 and the correlation comparison template. For example, when the received symbol is the symbol “-S”, a cross-correlation value having a sign opposite to that of the symbol “S” can be obtained. Further, when the received symbol is the symbol “0”, the cross-correlation value is a minute value (for example, −1).

  FIG. 18 is a diagram illustrating the relationship between the output value of the cross-correlation value and the data before encoding. Here, since a sequence of post-encoding data corresponding to “0” of pre-encoding data is stored as a correlation comparison template, the signal received by receiving apparatus 2 is input pre-encoding data “0” ( In the case of the symbol “S” corresponding to “0” before encoding shown in FIG. 10, a strong correlation can be obtained in any frame once (one place) in the symbol period.

  When the signal received by the receiving apparatus 2 is the symbol “−S” corresponding to the input pre-encoding data “1” (“1” of pre-encoding data shown in FIG. 10), the symbol “S” Can be obtained in any frame within the symbol period.

  When the cross-correlation value, which is the correlation calculation result by the DEM 49, is output as the correlation characteristics of the SFD, for example, a large positive output (+15), a large negative output (−15), and a small output (+1) with respect to the time axis. Or -1). Thus, when the received signal corresponds to “0” of the data before encoding, a large positive correlation value is output, and when the received signal corresponds to “1” of the data before encoding, a large negative correlation value is output. Is output. Also, when the received signal does not correspond to “0” or “1” of the pre-encoding data (when the sequence has no correlation), a minute value is output as the cross-correlation value.

  Next, in order to synchronize timing, the SYNC 51 detects a change point (edge) of the cross-correlation value based on the cross-correlation value output from the DEM 49. FIG. 19 is a diagram for explaining a change point of the cross-correlation value. As shown in the figure, as the cross-correlation value changing point, a point where the cross-correlation value changes from a positive output to a negative output via 0 output is detected. 20 and 21 are diagrams illustrating a specific example of a method for detecting a cross-correlation value change point. FIG. 20 shows a detection method when the cross-correlation value includes a strong positive cross-correlation value, a strong negative cross-correlation value, and no correlation (correlation value 0) (when symbol “0” is present). FIG. 21 shows a detection method when only a strong positive cross-correlation value and a strong negative cross-correlation value are included as cross-correlation values (when there is no symbol “0”). Thus, the SYNC 51 can detect the change point of the cross-correlation value using various filters.

  The SYNC 51 uses the detected cross-correlation value change point to perform timing synchronization such as frame synchronization (step S140), and inputs information related to timing synchronization to the DEM 49 as a signal s31.

  The DEM 49 performs demodulation processing and decoding processing on the signal s28 input from the ADC 48 using the signal s31, and outputs a signal s29 as demodulated data. Note that the cross-correlation value change point detection process and the timing synchronization process may be performed by the DEM 49.

  In this embodiment, the transmission apparatus 1 generates and transmits the symbol “S” and the symbol “−S”. However, the symbol “S” and the symbol “−S” are stored in the transmission apparatus 1 in advance. The stored symbols may be read out and transmitted to the receiving device 2 after reading out the stored symbols.

  In the present embodiment, a sequence corresponding to the symbol “S” (a template having a positive correlation value with the symbol “S”) is used as a correlation comparison template, and the received signal and the correlation comparison template are used. Is calculated using a sequence corresponding to the symbol “-S” (a template having a positive correlation value with the symbol “-S”) as a correlation comparison template. It is good also as calculating a cross correlation.

  As described above, according to Embodiment 1, when receiving apparatus 2 determines a correlation between a received signal and a correlation comparison template, a correlation value indicating a negative value and a correlation value indicating a positive value are used. It is possible to determine the correlation using. That is, the timing synchronization is established by performing edge detection using the positive correlation value and the negative correlation value obtained by the correlation calculation. This makes it possible to establish timing synchronization easily and accurately with a simple configuration.

Embodiment 2. FIG.
Next, a second embodiment of the present invention will be described with reference to FIG. In the second embodiment, in order to increase the communication capacity between the transmission apparatus 1 and the reception apparatus 2 over the communication capacity in the first embodiment, the data before encoding is configured with 2 bits in the data portion of the signal to be transmitted. Then, 2-bit data is encoded and transmitted.

  FIG. 22 is a diagram for explaining an example of the encoding process of the receiving apparatus according to the second embodiment. In Embodiment 2, for example, two types of M-sequences having a small correlation characteristic are easily encoded.

  In MOD32, encoding is performed for “00”, “01”, “10”, and “11” of the data before encoding. In FIG. 22, as conditions for setting a sequence of post-encoding data for “00” and “01” of pre-encoding data, M sequence degree 4, feedback tap (1, 4), and initial value “1111”. "Is used. In addition, as conditions for setting a sequence of post-encoding data for “10” and “11” of pre-encoding data, an M-sequence degree 4, a feedback tap (3, 4), and an initial value “0010” are set. The case where it is used is shown.

  The MOD 32 encodes “00” of pre-encoding data into a sequence of symbol “A”, and encodes “01” of pre-encoding data into a sequence of symbol “-A”. Also, the MOD 32 encodes “10” of the pre-encoding data into a symbol “B” sequence, and encodes “11” of the pre-encoding data into a symbol “−B” sequence.

  Here, “00” of the pre-encoding data is encoded into a sequence corresponding to the symbol “S” described in the first embodiment, and “01” of the pre-encoding data is described in the first embodiment. It is encoded into a sequence corresponding to the symbol “-S”. Thus, the MOD 32 performs encoding so that the pre-encoding data “00” and the pre-encoding data “01” have opposite polarities when encoded.

  Further, the MOD 32 encodes “10” and “11” of the pre-encoding data so as to be a series having a small correlation characteristic with the symbols “A” and “−A”. The encoding here is also performed so that the polarity after encoding is inverted between “10” and “11” of the data before encoding.

  That is, also in the second embodiment, when “10” of the pre-encoding data indicates “1” in the post-encoding data frame, “11” of the pre-encoding data is “0” in the post-encoding data frame. “1” and “0” are set for the encoded data. Further, when “10” of the pre-encoding data indicates “0” in the post-encoding data frame, “11” of the pre-encoding data indicates “1” in the post-encoding data frame. A frame “1” and a frame “0” of the converted data are set.

  In other words, the sequence set to “1” for the symbol “B” is set to “0” for the symbol “−B”, and the sequence set to “0” for the symbol “B” is set to the symbol “−B”. "Is set to" 1 ".

  MOD32 here generates, for example, “001000111101011” as the symbol “B” after encoding when the data before encoding is “10”, and after encoding when the data before encoding is “11”. "110111000010100" is generated as the symbol "-B".

  In the receiving apparatus 2, a correlator that determines the correlation of the sequence with respect to the symbol “A” or the symbol “−A”, and a correlation that determines the correlation of the sequence with respect to the symbol “B” or the symbol “−B”. Two types of correlators are prepared. Each correlator detects the correlation between the received symbol sequence and the correlation comparison template, and separates the 2-bit data.

  Here, the correlator that detects the symbol “A” stores the sequence corresponding to the symbol “A” as a correlation comparison template, and the correlator that detects the symbol “B” as the correlation comparison template into the symbol “B”. Store the corresponding series.

FIG. 23 is a diagram of an example of correlation characteristics detected by the receiving apparatus according to the second embodiment.
As shown in the figure, when a symbol “A” or a symbol “−A” is transmitted from the transmission apparatus 1 and a received signal is detected by a correlator capable of detecting the symbol “A” (the square mark in the figure). The data “00” before encoding and the data “01” before encoding are detected as large cross-correlation values.

  When symbol “A” is transmitted from transmitter 1, a large positive cross-correlation value (15) is obtained, so this case is determined to be “00” of pre-encoding data. On the other hand, when the symbol “-A” is transmitted from the transmission apparatus 1, a large negative cross-correlation value (−15) is obtained. Therefore, this case is determined as pre-encoding data “01”.

  In addition, when the symbol “B” or the symbol “−B” is transmitted from the transmission apparatus 1 and the received signal is detected by the correlator capable of detecting the symbol “B” (the point plotted by the inverted triangle mark in the figure). ), Pre-encoding data “10” and pre-encoding data “11” are detected as large cross-correlation values.

  When the symbol “B” is transmitted from the transmission apparatus 1, a large positive cross-correlation value (15) is obtained, so this case is determined to be “10” of the pre-encoding data. On the other hand, when the symbol “−B” is transmitted from the transmission apparatus 1, a large negative cross-correlation value (−15) is obtained. Therefore, this case is determined to be pre-encoding data “11”.

  Here, the case where the symbol “-A” and the symbol “B” are simultaneously transmitted from the transmission apparatus 1 is shown so that the symbol “-A” and the symbol “B” are detected in the 45th frame. Further, the case where the symbol “A” and the symbol “−B” are simultaneously transmitted from the transmission device 1 so that the symbol “A” and the symbol “−B” are detected in the 90th frame is shown.

  In addition, when a symbol “A” or a symbol “−A” is transmitted from the transmission apparatus 1 and a received signal is detected by a correlator capable of detecting the symbol “B” (points plotted by triangles in the figure). Only a small cross-correlation value is detected.

  In addition, when the symbol “B” or the symbol “−B” is transmitted from the transmission apparatus 1 and a received signal is detected by a correlator capable of detecting the symbol “A” (points plotted by circles in the figure). Only a small cross-correlation value is detected.

In Embodiment 2, the pre-encoding data is composed of 2 bits in the data portion of the signal to be transmitted, and the 2-bit data is encoded and transmitted. However, the pre-encoding data is 3 bits or more. It is also possible to configure and transmit data of 3 bits or more. In this case, the receiving apparatus prepares the number of correlators that can identify the data for the types set as the pre-encoding data. For example, the receiving apparatus 2 prepares 2 ⁿ / 2 correlators for 2 ⁿ (n is a natural number) types of pre-transmission data.

  As described above, according to the second embodiment, four types of (2 bits) pre-transmission data are encoded so as to have low correlation with each other, and the data are separated by two correlators. The communication capacity between the receiving apparatuses 2 is twice that in the first embodiment.

Embodiment 3 FIG.
Next, a third embodiment of the present invention will be described. In the third embodiment, in order to increase the communication capacity between the transmission apparatus 1 and the reception apparatus 2 more than the communication capacity in the first embodiment, the data before encoding is configured with 2 bits in the data portion of the signal to be transmitted. At the same time, the position of the chip period Tc is shifted by MOD32. Then, position detection is performed in combination with a method generally called PPM (Pulse Phase Modulation). The receiving apparatus 2 uses both the PPM position detection and the cross-correlation circuit (DEM 49) used in the first embodiment.

  As described above, according to the third embodiment, the pre-encoding data is composed of 2 bits and the position of the chip period Tc is shifted, so that the communication capacity between the transmission device 1 and the reception device 2 is increased. It becomes possible to make it larger than the case of the form 1.

Embodiment 4 FIG.
Next, a fourth embodiment of the present invention will be described. In the fourth embodiment, in order to increase the communication capacity between the transmission apparatus 1 and the reception apparatus 2 over the communication capacity in the first embodiment, a predetermined symbol time (for example, 1) is used in the data portion of the signal to be transmitted. During the symbol time) continue to transmit “0” or “1”. By providing a circuit for determining X in the receiving apparatus 2 in this case, the transmitting apparatus 1 can transmit three values “0”, “1”, and “X” in one symbol time. .

  Thus, according to the fourth embodiment, “X” different from “0” and “1” can be transmitted by continuously transmitting “0” for a predetermined symbol time in the data portion. Therefore, the receiving apparatus 2 can receive three values “0”, “1”, and “X” in one symbol time. Therefore, the communication capacity between the transmission device 1 and the reception device 2 can be made larger than that in the first embodiment.

  Note that a plurality of methods described in the second to fourth embodiments may be combined to perform wireless communication between the transmission device 1 and the reception device 2 in the first embodiment. Thereby, the communication capacity between the transmission apparatus 1 and the receiving apparatus 2 becomes larger than the case of Embodiment 2-4. Further, the transmission device 1 and the reception device 2 described in the first to fourth embodiments may be applied to a modulator.

  As described above, the receiving apparatus and the receiving method according to the present invention are suitable for timing synchronization processing of impulse transmission wireless communication using a wide band.

FIG. 3 is a functional block diagram illustrating a configuration of a transmission device according to the first exemplary embodiment; 2 is a functional block diagram showing a configuration of a receiving apparatus according to the first exemplary embodiment; FIG. 1 is a circuit block diagram illustrating a circuit configuration of a transmission apparatus according to a first embodiment; 1 is a circuit block diagram illustrating a circuit configuration of a receiving device according to a first exemplary embodiment; It is a figure which shows an example of a structure of the signal transmitted from a transmitter. It is a figure for demonstrating the relationship between a symbol and a flame | frame. It is a figure which shows an example of a structure of a symbol. It is a figure for demonstrating the structure according to the symbol type. 3 is a flowchart illustrating a processing procedure of the transmission device according to the first exemplary embodiment; It is a figure for demonstrating an example of the code process performed by MOD. It is a figure which shows an example of the transmission waveform of the signal output from DAC. It is a figure which shows an example of the transmission waveform of the signal output from Mixer. 3 is a flowchart illustrating a processing procedure of the receiving apparatus according to the first exemplary embodiment. It is a figure which shows an example of the received waveform of the signal which a receiver receives. It is a figure which shows an example of the digital signal which passes ADC. It is a figure for demonstrating the received signal after passing a time filter. FIG. 3 is a diagram for explaining asynchronous detection processing of the receiving device according to the first exemplary embodiment; It is a figure which shows the relationship between the output value of a cross correlation value, and the data before encoding. It is a figure for demonstrating the change point of a cross correlation value. It is a figure (1) which shows the specific example of the detection method of the change point of a cross correlation value. It is FIG. (2) which shows the specific example of the detection method of the change point of a cross correlation value. FIG. 9 is a diagram for explaining an example of encoding processing of the receiving apparatus according to the second exemplary embodiment; FIG. 10 is a diagram illustrating an example of correlation characteristics detected by the receiving apparatus according to the second embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Transmission apparatus 2 Reception apparatus 11 Signal generation part 12 Signal transmission part 13 Control part 21 Signal reception part 22 Demodulation part 23 Control part 31 FRAMER
32 MOD
33 DAC
34, 45 LPF
35,44 Mixer
36 BPF
37, 41 Antenna 38, 50 LOCAL
42 BPF
43 LNA
46 Amplitude power conversion block 47 Integration circuit 48 ADC
49 DEM
51 SYNC
Tc Chip period Tf Frame period Ts Symbol period

Claims (2)

A reception device that receives a transmission signal including a preamble and establishes timing synchronization using a preamble in the reception signal,
The transmitting side changes the first symbol composed of a plurality of frames each indicating “0”, “+1”, or “−1” and “+1” or “0” in the frame sequence constituting the first symbol. In the case of generating a preamble including the second symbol set to “−1” and “+1” or “−1” set to “0” and performing signal transmission including the preamble, the preamble A reception unit that receives a signal including a signal and executes a predetermined reception process;
The signal output from the receiving unit is squared, and then the squared received signal and the squared received signal corresponding to the first symbol or the squared received signal corresponding to the second symbol A correlation value obtained as a result of calculation by calculating a correlation with a previously known template in which the correlation value with one of the signals is a positive value and the correlation value with the other is a negative value. A demodulator that establishes timing synchronization based on:
A receiving apparatus comprising: A signal reception method for receiving a transmission signal including a preamble and establishing timing synchronization using the preamble in the reception signal,
The transmitting side changes the first symbol composed of a plurality of frames each indicating “0”, “+1”, or “−1” and “+1” or “0” in the frame sequence constituting the first symbol. In the case of generating a preamble including the second symbol set to “−1” and “+1” or “−1” set to “0” and performing signal transmission including the preamble, the preamble A reception step of receiving a signal including a signal and executing a predetermined reception process;
The received signal is squared, and then the squared received signal and the squared received signal corresponding to the first symbol or the squared received signal corresponding to the second symbol Calculate the correlation with a previously known template held so that the correlation value with one becomes a positive value and the correlation value with the other becomes a negative value, and the timing is based on the correlation value obtained as the calculation result A demodulation step to establish synchronization;
A receiving method comprising:

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