JP7199619B2 - Transmitting device, receiving device, spread spectrum communication system, control circuit, storage medium, transmitting method and receiving method - Google Patents

Description

The present disclosure relates to a transmitting device, a receiving device, a spread spectrum communication system, a control circuit, a storage medium, a transmitting method, and a receiving method that perform spread spectrum communication.

Among the spread spectrum communications, the direct sequence system converts a modulated signal primarily modulated by PSK (Phase Shift Keying), FSK (Frequency Shift Keying), etc. into a chirp signal, PN (Pseudorandom Noise) sequence, etc. as a spread sequence. , the bandwidth is wider than the bandwidth of the primary modulation and is transmitted. In reception processing, despreading is performed by multiplying by a sequence having the inverse characteristic of the spreading sequence, and a modulated signal is extracted. By performing such processing, a power gain corresponding to the length of the spreading sequence multiplied by one modulated signal can be obtained. Suitable for In recent years, in LPWA (Low Power Wide Area) adopted as a wireless communication system for IoT (Internet of Things) devices, spread spectrum communication including the above-described direct sequence system is utilized.

Chirp signals include an up-chirp signal whose frequency linearly increases with time and a down-chirp signal whose frequency linearly decreases with time. Also, as an example of the above-mentioned sequence, there is a ZC (Zadoff-Chu) sequence, which is one of CAZAC (Constant Amplitude Zero Auto Correlation) sequences. Since the amplitude of the transmission signal using such a sequence has a constant envelope, power efficiency is high. In addition, such sequences are generally used as known sequences in communication systems because they have good correlation characteristics in which the cross-correlation between sequences before and after the cyclic time shift is uncorrelated by cyclic time shifting. . Patent Document 1 discloses a technique of performing timing synchronization in a receiver using a chirp signal as a known sequence in spread spectrum communication.

Japanese Patent No. 5699142

However, according to the above-described prior art, when direct spreading is performed in spread spectrum communication, the length of the spreading sequence is increased by 2, 4, 8, . . . However, there is a problem that the circuit scale of timing synchronization processing increases. Furthermore, when a transmitting device uses a plurality of antennas to obtain diversity gain and transmits using different spreading sequences so as not to interfere between signals transmitted from each antenna, the receiving device uses each spreading sequence as timing synchronization processing. Since it is necessary to perform synchronization processing with respect to, there is a problem that the circuit scale increases further.

The present disclosure has been made in view of the above. It is an object of the present invention to obtain a transmitter capable of timing synchronization.

To solve the above-described problems and achieve the object, the present disclosure is a transmitting device that performs wireless communication with a receiving device in a spread spectrum communication system. The transmitting apparatus includes a spreading processing unit that performs spreading processing by multiplying a modulated signal obtained by modulating a transmission bit sequence by a spreading sequence, and a transmission path for the signal spread by the spreading processing unit based on the number of transmitting antennas. A channel coding unit that performs coding, a synchronization chirp signal generation unit that generates a synchronization chirp signal for timing synchronization in a receiving device, and a block unit signal generated by cyclically time-shifting the synchronization chirp signal, A time shift unit for generating known sequences composed of signals of a plurality of blocks in the same number as the number of transmission antennas, each connected to a different transmission antenna, and a data sequence and a known sequence channel-encoded by a channel encoding unit. are combined to generate different transmission signals and transmit them from the transmission antennas.

The transmitting device according to the present disclosure has the effect of enabling accurate timing synchronization while suppressing an increase in the circuit scale of timing synchronization processing in the receiving device when signals are transmitted using a plurality of antennas in a spread spectrum communication system. play.

A diagram showing a configuration example of a spread spectrum communication system according to the present embodiment FIG. 1 shows an example of a chirp signal used in the spread spectrum communication system according to the present embodiment; A second diagram showing an example of a chirp signal used in the spread spectrum communication system according to the present embodiment A diagram showing an example of a known sequence used in a transmission signal transmitted from the first transmission antenna of the transmission apparatus according to this embodiment A diagram showing an example of a known sequence used in a transmission signal transmitted from the second transmitting antenna of the transmitting apparatus according to this embodiment Block diagram showing a configuration example of a transmission device according to this embodiment Flowchart showing the operation of the transmission device according to the present embodiment FIG. 4 is a diagram showing an example frame of each transmission signal generated and transmitted by the transmission device according to the present embodiment; A diagram showing an example of a known sequence portion of a composite signal received by a receiving apparatus when the transmitting apparatus according to the present embodiment transmits transmission signals using two transmitting antennas. FIG. 10 is a diagram showing an example of a known sequence for correlation processing generated to detect the start position of a chirp signal for synchronization with respect to a synthesized signal in the receiving apparatus according to this embodiment; A diagram showing an output image when the receiving apparatus according to the present embodiment receives the synthesized signal shown in FIG. 9 and performs cross-correlation using the known sequence for correlation processing shown in FIG. 10 to calculate the correlation value. FIG. 11 is a diagram showing an image of synthesizing the peaks for the correlation values calculated in FIG. 11 by the receiving apparatus according to the present embodiment. Block diagram showing a configuration example of a receiving device according to this embodiment Flowchart showing the operation of the receiving device according to this embodiment Block diagram showing a configuration example of a timing synchronization unit provided in a receiving apparatus according to this embodiment Flowchart showing the operation of the timing synchronization unit included in the receiving apparatus according to this embodiment FIG. 4 is a diagram showing a known sequence portion of a composite signal received by a receiving apparatus when the transmitting apparatus according to this embodiment transmits transmission signals using three transmitting antennas; FIG. 11 is a diagram showing an image of combining correlation value peaks by a receiving apparatus when the transmitting apparatus according to the present embodiment transmits transmission signals using three transmitting antennas; FIG. 4 is a diagram showing a known sequence portion of a composite signal received by a receiving apparatus when the transmitting apparatus according to this embodiment transmits transmission signals using four transmitting antennas; FIG. 10 is a diagram showing an image of combining correlation value peaks by a receiving apparatus when the transmitting apparatus according to the present embodiment transmits transmission signals using four transmitting antennas; FIG. 4 is a diagram showing a configuration example of a processing circuit provided in the transmitting apparatus according to the present embodiment when the processing circuit is realized by a processor and a memory; FIG. 4 is a diagram showing an example of a processing circuit in a case where the processing circuit included in the transmitting apparatus according to the present embodiment is configured with dedicated hardware;

A transmitting device, a receiving device, a spread spectrum communication system, a control circuit, a storage medium, a transmitting method, and a receiving method according to embodiments of the present disclosure will be described below in detail with reference to the drawings.

Embodiment.
FIG. 1 is a diagram showing a configuration example of a spread spectrum communication system 300 according to this embodiment. Spread spectrum communication system 300 includes transmitting apparatus 100 and receiving apparatus 200 . The spread spectrum communication system 300 shown in FIG. 1 simply shows an image of the operation of the transmitting apparatus 100 and the receiving apparatus 200 that perform wireless communication using the spread spectrum communication method.

Transmitting apparatus 100 performs primary modulation on a transmission bit sequence using PSK, FSK, or the like. Transmitting apparatus 100 directly spreads the modulated signal using a chirp signal as a spreading sequence, thereby widening the signal bandwidth by the length of the spreading sequence. FIG. 1 shows the state in which the bandwidth of the modulated signal is converted from narrowband to wideband by direct spreading. Transmitting apparatus 100 transmits a spread signal with a wider bandwidth.

The receiver 200 performs timing synchronization with respect to the received signal. Receiving apparatus 200 detects the beginning position of a received frame, which is a signal after spreading, by timing synchronization, multiplies a sequence having an inverse characteristic to the spreading sequence used in transmitting apparatus 100, despreads, Extract the signal. A sequence having an inverse characteristic to the spreading sequence used in transmitting apparatus 100 is, for example, a sequence whose phase value is inverted by a complex signal in the case of a constant envelope signal such as a ZC sequence used for a chirp signal. FIG. 1 shows a state in which the bandwidth of the received signal is converted from wideband to narrowband by despreading. The narrowband received signal corresponds to the signal before spreading in transmitting apparatus 100 . Receiving apparatus 200 obtains a received bit sequence by performing demodulation processing on the signal before spreading.

Note that FIG. 1 simply shows an image of the operation of the transmitting device 100 and the receiving device 200, so only baseband signal processing is described, and ADC (Analog to Digital Converters) and DAC (Digital to Analog Converters) are described. , power amplifier, and AGC (Auto Gain Control) are omitted. Detailed configurations and operations of transmitting apparatus 100 and receiving apparatus 200 using functional blocks will be described later.

FIG. 2 is a first diagram showing an example of a chirp signal used in spread spectrum communication system 300 according to this embodiment. FIG. 3 is a second diagram showing an example of a chirp signal used in spread spectrum communication system 300 according to this embodiment. 2 and 3, the horizontal axis indicates time and the vertical axis indicates frequency. FIG. 2 shows the time and frequency characteristics of an up-chirp signal, which is a chirp signal. As shown in FIG. 2, the up-chirp signal is a chirp signal whose frequency linearly increases with time. FIG. 3 shows the time and frequency characteristics of a down-chirp signal, which is a chirp signal. As shown in FIG. 3, the down-chirp signal is a chirp signal whose frequency linearly decreases with time. In the following description, an up-chirp signal is used as an example, but either an up-chirp signal or a down-chirp signal, or a signal obtained by combining both may be used as the known sequence.

Next, a known sequence known between transmitting apparatus 100 and receiving apparatus 200, which is used when receiving apparatus 200 performs timing synchronization in the present embodiment, will be described. Here, as an example, a case where transmitting apparatus 100 includes two transmitting antennas and transmits transmission signals from the two transmitting antennas will be described. FIG.4 is a diagram showing an example of a known sequence used in a transmission signal transmitted from the first transmitting antenna of transmitting apparatus 100 according to this embodiment. FIG. 5 is a diagram showing an example of known sequences used in transmission signals transmitted from the second transmitting antenna of transmitting apparatus 100 according to this embodiment. 4 and 5, the horizontal axis indicates time and the vertical axis indicates frequency. The chirp signals shown in FIGS. 4 and 5 are up-chirp signals that increase by one frequency corresponding to one square on the vertical axis per time slot corresponding to one square on the horizontal axis in the figures.

In this embodiment, as shown in FIGS. 4 and 5, five time slots constitute one block and two blocks constitute one known sequence. As for the known sequences used in the first transmitting antenna shown in FIG. 4, block #1 is a sequence that sequentially increases from frequency (1), and block #2 is a sequence that sequentially increases from frequency (4). do. In this embodiment, since frequencies (1) to (4) are assumed to be the channel bandwidth, processing is performed so that frequency (4) is cyclically shifted to frequency (1). That is, when the sequence of block #1 is used as a reference, the sequence of block #2 is a sequence that is time-shifted in the negative direction by one frequency. The known sequence used by the second transmitting antenna shown in FIG. 5 is obtained by replacing the sequence order of block #1 and block #2 with respect to the known sequence used by the first transmitting antenna.

Note that the frequency components indicated by dotted lines in FIGS. 4 and 5 are actually signal components to be transmitted, but will be omitted in the following description. These frequency components are components that are not detected in the timing synchronization processing of receiving apparatus 200, which will be described later. In FIGS. 4 and 5, since the dotted line portion occupies one-fifth of the spreading sequence length of each block, the power loss seems to be large when non-detection occurs. However, when the spreading sequence length is lengthened for long-distance communication, for example, the number of time slots and frequency components is increased to 1024, the proportion occupied by the dotted line becomes very small, 1/1025, and is not detected. It can be said that the amount of decrease in synchronization accuracy due to this is very small.

The configuration and operation of transmitting device 100 will be described in detail. FIG. 6 is a block diagram showing a configuration example of transmitting apparatus 100 according to this embodiment. Transmitting apparatus 100 includes modulating section 110, chirp signal generating section 120, spreading processing section 130, channel coding section 140, chirp signal generating section 150 for synchronization, time shifting section 160, and waveform shaping combining section. 170-1, 170-2 and transmitting antennas 180-1, 180-2. Transmitting antenna 180-1 corresponds to the aforementioned first transmitting antenna, and transmitting antenna 180-2 corresponds to the aforementioned second transmitting antenna. In the following description, waveform shaping and combining sections 170-1 and 170-2 may be referred to as waveform shaping and combining section 170 when not distinguished, and may be referred to as transmitting antenna 180 when transmitting antennas 180-1 and 180-2 are not distinguished. be. FIG. 7 is a flow chart showing the operation of transmitting apparatus 100 according to the present embodiment.

Modulation section 110 performs primary modulation on a transmission bit sequence using PSK, FSK, or the like (step S101). Modulation section 110 performs processing corresponding to “primary modulation” in FIG.

The chirp signal generator 120 generates a chirp signal for spreading processing (step S102). Although a chirp signal is used as the spreading sequence here, chirp signal generation section 120 may generate other spreading sequences as long as the known sequence is a chirp signal in this embodiment.

The spreading processing unit 130 performs direct spreading by multiplying the modulated signal primary-modulated by the modulating unit 110 by the chirp signal generated by the chirp signal generating unit 120 (step S103). The chirp signal generation unit 120 and the spreading processing unit 130 perform processing corresponding to "direct spreading" in FIG.

Since transmission path coding section 140 transmits the spread signal spread by spreading processing section 130 from two transmitting antennas 180-1 and 180-2, transmission based on the number of transmitting antennas 180 is performed. Road coding is performed (step S104). As the channel coding, any method may be used as long as it does not interfere between the transmission signals transmitted from the two transmitting antennas 180-1 and 180-2. If it is a signal, it may be a process of frequency shifting one side with respect to the other side. Channel coding section 140 outputs a data sequence, which is a signal after channel coding, to waveform shaping/synthesizing sections 170-1 and 170-2.

The synchronization chirp signal generator 150 generates a chirp signal for timing synchronization in the receiving apparatus 200 (step S105). Specifically, synchronization chirp signal generating section 150 generates a signal of block #1 in the known sequence for transmitting antenna 180-1 shown in FIG.

Time shifting section 160 acquires the signal of block #1 for transmitting antenna 180-1 from chirp signal generating section 150 for synchronization, time-shifts the signal of block #1 for transmitting antenna 180-1, Generate block #2 signals for transmit antenna 180-1. Time shift section 160 uses the acquired signal of block #1 for transmitting antenna 180-1 and the generated signal of block #2 for transmitting antenna 180-1 to generate the signal for transmitting antenna 180-1 shown in FIG. and a known sequence for transmit antenna 180-2 shown in FIG. That is, the time shifter 160 generates block-unit signals obtained by cyclically time-shifting the synchronization chirp signal, and generates the same number of known sequences composed of signals of a plurality of blocks as the number of transmission antennas 180 (step S106). Note that the amount of time shift in the time shift section 160 may be zero for some blocks. Time shift section 160 outputs the known sequence for transmission antenna 180-1 to waveform shaping synthesis section 170-1, and outputs the known sequence for transmission antenna 180-2 to waveform shaping synthesis section 170-2.

Waveform shaping/synthesizing section 170-1 combines the data sequence obtained from channel coding section 140 and the known sequence for transmitting antenna 180-1 obtained from time shifting section 160, for example, in the order of the known sequence and the data sequence. Synthesize so that Waveform shaping/combining section 170-1 transmits the combined and framed signal from transmitting antenna 180-1 as a first transmission signal. Similarly, waveform shaping/synthesizing section 170-2 converts the data sequence obtained from channel coding section 140 and the known sequence for transmitting antenna 180-2 obtained from time shifting section 160 into known series, data Synthesize so that it is in the order of the series. Waveform shaping/combining section 170-2 transmits the combined and framed signal from transmitting antenna 180-2 as a second transmission signal. In this way, the waveform shaping/synthesizing units 170-1 and 170-2 are connected to different transmitting antennas 180, respectively, and the data sequence channel-encoded by the channel encoding unit 140 and the data sequence generated by the time shift unit 160 are A different transmission signal is generated by synthesizing the obtained known sequence and transmitted from the transmission antenna 180 (step S107). The number of waveform shaping/synthesizing units 170 is the same as the number of transmitting antennas 180 .

FIG. 8 is a diagram showing a frame example of each transmission signal generated and transmitted by transmitting apparatus 100 according to the present embodiment. In FIG. 8, the horizontal axis indicates time. In addition, in the example of FIG. 8, the known sequence is added to the head of the transmission signal, but this is an example and the present invention is not limited to this. Waveform shaping/synthesizing section 170 may add the known sequence to a position other than the beginning of the transmission signal.

In the present embodiment, the number of transmitting antennas 180 included in transmitting apparatus 100 is two or more. A transmission signal transmitted from each transmission antenna 180 of transmission apparatus 100 includes a known sequence in which the cyclic time shift amount of the chirp signal for synchronization is different. The known sequence is composed of a number of blocks equal to or greater than the number of transmission antennas 180, and the cyclic time shift amount of the chirp signal for synchronization differs for each transmission signal transmitted from each transmission antenna 180 at the same block position. The known sequence has the same number of candidates for the cyclic time shift amount obtained by accumulating the cyclic time shift amounts in all blocks for each transmission signal.

Next, reception processing of the reception device 200 will be described. FIG. 9 shows an example of a known sequence portion of a combined signal received by receiving apparatus 200 when transmitting apparatus 100 according to the present embodiment transmits transmission signals using two transmitting antennas 180-1 and 180-2. FIG. 4 is a diagram showing; In FIG. 9, the horizontal axis indicates time and the vertical axis indicates frequency. In FIG. 9, the black line indicates the known sequence of the signal transmitted and received from transmitting antenna 180-1, and the white line indicates the known sequence of the signal transmitted and received from transmitting antenna 180-2. FIG. 10 is a diagram showing an example of a known sequence for correlation processing that is generated in order to detect the start position of a chirp signal for synchronization with respect to a combined signal in receiving apparatus 200 according to this embodiment. Receiving apparatus 200 may generate a sequence for one block out of a known sequence consisting of two blocks. The known sequences generated by receiving apparatus 200 correspond to the blocks of the known sequences shown in FIGS. 4 and 5, excluding the dotted lines.

FIG. 11 shows the correlation value calculated by performing cross-correlation using the known sequence for correlation processing shown in FIG. 10 when receiving apparatus 200 according to the present embodiment receives the combined signal shown in FIG. It is a figure which shows an output image. FIG. 11(a) is the same as FIG. 9 described above. In FIG. 11(b), the horizontal axis indicates time, and the vertical axis indicates the correlation value. When receiving apparatus 200 performs cross-correlation using the known sequences for correlation processing shown in FIG. , time (1), time (2), time (6), and time (7), respectively. Normally, the propagation loss between transmitting antenna 180-1 and the receiving antenna of receiving apparatus 200 and the propagation loss between transmitting antenna 180-2 and the receiving antenna of receiving apparatus 200 have different values. In the example, they are treated as the same propagation loss. After detecting the peak of the correlation value, receiving apparatus 200 synthesizes each peak of the correlation value as will be described later.

In the present embodiment, the known sequence is made up of only the up-chirp signal. After performing correlation processing on each series of chirp signals individually, the obtained correlation values are combined. In this case, in order to make receiving apparatus 200 the same circuit scale as that of the present embodiment, each sequence of the up-chirp signal and the down-chirp signal needs to be a known sequence with a total length of four time slots, with each sequence corresponding to two time slots. be.

FIG. 12 is a diagram showing an image of how receiving apparatus 200 according to the present embodiment synthesizes peaks for the correlation values calculated in FIG. In each diagram of FIG. 12, the horizontal axis indicates time, and the vertical axis indicates the correlation value. FIG. 12(a) is similar to FIG. 11(b) described above. Receiving apparatus 200 first performs inter-block synthesis on the output of correlation processing, and obtains the power sum with the correlation value one block time earlier. As a result, the correlation value characteristic shown in FIG. 12(b) is obtained. Next, receiving apparatus 200 performs intra-block combining on the correlation value characteristic of FIG. Take the power sum with the previous correlation value. As a result, the correlation value characteristic shown in FIG. 12(c) is obtained. After performing the above processing, receiving apparatus 200 identifies the position of the known sequence by detecting the peak of the final correlation value characteristic.

In the example of FIG. 12, since the correlation value peak is obtained at the beginning of time (2) of the known sequence, it can be seen that the position one time slot before the peak position is the beginning position of the known sequence. As a feature of the correlation value peak detection method of receiving apparatus 200 of the present embodiment, even if the transmission signal of one of transmitting antennas 180 of transmitting apparatus 100 is not obtained, either the black line or the white line shown in FIG. is no longer obtained as a correlation value, and a correlation value peak is obtained at the same position for the transmission signal of the other transmitting antenna 180 of the transmitting apparatus 100 . Therefore, receiving apparatus 200 can perform timing synchronization as long as the transmission signal of any of transmitting antennas 180 can be received regardless of the state of the radio propagation path between transmitting apparatus 100 and receiving apparatus 200 . Moreover, such a feature can be said that the same timing synchronization method can be applied to the receiving apparatus 200 even if the transmitting apparatus 100 has only one transmitting antenna 180 .

The configuration and operation of receiving device 200 will be described in detail. FIG. 13 is a block diagram showing a configuration example of receiving apparatus 200 according to this embodiment. Receiving apparatus 200 includes receiving antenna 210 , band limiting section 220 , timing synchronization section 230 , despreading processing section 240 and demodulation section 250 . FIG. 14 is a flowchart showing the operation of receiving apparatus 200 according to this embodiment.

The band-limiting unit 220 band-limits the received signal received by the receiving antenna 210 using a band-limiting filter (step S201). Band-limiting section 220 extracts only the signal of the desired band, that is, the information of the reception channel by band-limiting.

The timing synchronization unit 230 performs timing synchronization using the reception channel information extracted by the band limiting unit 220, and detects the start position of the reception frame included in the reception signal (step S202). The timing synchronization unit 230 performs processing corresponding to "timing synchronization" in FIG.

The configuration and operation of timing synchronization section 230 will be described in detail. FIG. 15 is a block diagram showing a configuration example of timing synchronization section 230 included in receiving apparatus 200 according to this embodiment. The timing synchronization unit 230 includes a correlation sequence generation unit 231 , a correlation processing unit 232 , an inter-block synthesis unit 233 , an intra-block synthesis unit 234 and a peak detection unit 235 . FIG. 16 is a flowchart showing the operation of timing synchronization section 230 included in receiving apparatus 200 according to this embodiment. In the timing synchronization unit 230, the correlation sequence generator 231 generates a known sequence for correlation processing as shown in FIG. 10 (step S301). The known sequence for correlation processing includes all or part of the synchronization chirp signal for timing synchronization generated by synchronization chirp signal generation section 150 of transmitting apparatus 100 .

The correlation processing unit 232 performs correlation processing between the desired band signal extracted by the band limiting unit 220 and the known sequence for correlation processing generated by the correlation sequence generation unit 231 (step S302). Correlation processing by the correlation processing unit 232 provides a correlation value peak as shown in FIG. 12(a).

The inter-block synthesizing unit 233 performs inter-block synthesis on the output from the correlation processing unit 232 (step S303) to synthesize the power of all blocks of the known series. Correlation value peaks such as those shown in FIG.

The intra-block combining unit 234 performs intra-block combining on the output from the inter-block combining unit 233 (step S304), and combines the correlation values for the time shift added by the transmitting apparatus 100. FIG. Correlation value peaks such as those shown in FIG.

The peak detection unit 235 detects the correlation value peak from the output from the intra-block synthesis unit 234, that is, the correlation value peak shown in FIG. 12(c), and specifies the head position of the received frame (step S305). The peak detector 235 outputs position information specifying the head position of the received frame as a result of timing synchronization.

In this way, timing synchronization section 230 generates a known sequence for correlation processing that includes all or part of a synchronization chirp signal for timing synchronization generated in transmitting apparatus 100, and generates a signal of a desired band and a correlation processing known sequence. A correlation value peak is detected from a correlation value obtained by performing correlation processing with a known sequence, and timing synchronization is performed to specify the head position of a received frame included in the received signal. Timing synchronization section 230 combines the peak values obtained by the correlation processing between blocks of a known sequence composed of a plurality of blocks of signals with different cyclic time shift amounts, and then combines within the block. Timing synchronization is performed by performing peak detection.

Returning to the description of FIGS. 13 and 14. FIG. Despreading processing section 240 identifies the position of the received frame from the signal of the desired band extracted by band limiting section 220 using the position information obtained from timing synchronization section 230, Multiply a sequence having an inverse characteristic to the sequence and despread (step S203). Despreading processing section 240 extracts the signal before spreading in transmitting apparatus 100 by despreading. The despreading processing unit 240 performs processing corresponding to "despreading" in FIG.

The demodulator 250 extracts the data series from the pre-spread signal and performs demodulation processing (step S204). Demodulator 250 obtains a received bit sequence through demodulation processing. The demodulator 250 performs processing corresponding to "demodulation" in FIG.

As described above, in the spread spectrum communication system 300, even when the transmitting apparatus 100 transmits using a plurality of transmitting antennas 180, the receiving apparatus 200 performs the above-described timing synchronization, thereby performing simple processing and high accuracy. It becomes possible to perform timing synchronization.

In this embodiment, the case where the number of transmitting antennas 180 of transmitting apparatus 100 is two has been described, but this is an example, and the case where the number of transmitting antennas 180 of transmitting apparatus 100 is three is also applicable. Specifically, for the known sequence for timing synchronization, each time the number of transmitting antennas 180 of transmitting apparatus 100 is increased by one, the number of time shift candidates is increased by one or more in each block, and the number of blocks to be configured is also one. increase more than

FIG. 17 is a diagram showing a known sequence portion of a combined signal received by receiving apparatus 200 when transmitting apparatus 100 according to the present embodiment transmits transmission signals using three transmitting antennas 180. In FIG. FIG. 18 is a diagram showing an image of combining correlation value peaks by receiving apparatus 200 when transmitting apparatus 100 according to the present embodiment transmits transmission signals using three transmitting antennas 180. In FIG. FIG. 19 is a diagram showing a known sequence portion of a combined signal received by receiving apparatus 200 when transmitting apparatus 100 according to the present embodiment transmits transmission signals using four transmitting antennas 180. In FIG. FIG. 20 is a diagram showing an image of correlation value peaks combined by receiving apparatus 200 when transmitting apparatus 100 according to the present embodiment transmits transmission signals using four transmitting antennas 180. In FIG. 17 to 20 , black lines indicate signals corresponding to signals transmitted from the first transmitting antenna of transmitting apparatus 100, and signals corresponding to signals transmitted from the second transmitting antenna of transmitting apparatus 100 are represented by black lines. A white line indicates a signal corresponding to a signal transmitted from the third transmitting antenna of the transmitting apparatus 100, and a dotted line indicates the signal. 19 and 20, the signal corresponding to the signal transmitted from the fourth transmitting antenna of transmitting apparatus 100 is indicated by triple lines.

18 and 20, only blocks for which the maximum peak value is obtained by performing inter-block combining and intra-block combining in receiving apparatus 200 are described, and notation of correlation values of adjacent blocks is omitted. doing. As for the configuration of the known sequence included in the transmission signal transmitted from each transmission antenna 180 of the transmission device 100, for example, when the number of transmission antennas 180 is three, in block #1 the time shift amount of the black line is 0 and the white line is 1, and the time shift amount of the dotted line is 2. When the time shift amounts for three blocks are arranged numerically, the transmitting apparatus 100 cyclically shifts the time shift amounts for each block such as 0.1.2, 1.2.0, and 2.0.1. , timing synchronization in the receiver 200 becomes possible. Receiving apparatus 200 performs correlation processing on the received signal using the same known sequence for correlation processing as in the case where the number of transmitting antennas 180 is two, then performs inter-block synthesis for three blocks, and finally By synthesizing the peak values corresponding to the time shift amounts 0, 1, and 2 in the intra-block synthesis, the correlation value characteristic shown in FIG. 18 is obtained. Even when the number of transmitting antennas 180 of transmitting apparatus 100 is four, the number of blocks of the known sequence is increased by one, and the number of time shift amount candidates for each block is also increased by one, compared to the case of three transmitting antennas 180. By doing so, it is possible to respond.

Based on the above description, the following three generation conditions can be obtained by generalizing the pattern generation method for the known sequence. First, a known sequence is configured with a number of blocks equal to or greater than the number of transmitting antennas 180 of transmitting apparatus 100, and a number equal to or greater than the number of transmitting antennas 180 of transmitting apparatus 100 is provided as time shift amount candidates for each block. Second, the known signals are arranged in each block with different time shift amounts so that the signals of the transmission antennas 180 of the transmission device 100 do not interfere with each other. The third method is to use each time shift amount candidate the same number of times for the known sequence for each transmitting antenna 180 of the transmitting apparatus 100, totaling all blocks constituting the known sequence.

Next, the hardware configuration of transmission device 100 will be described. In transmitting apparatus 100, transmitting antenna 180 is realized by an antenna element. Modulation section 110, chirp signal generation section 120, spreading processing section 130, channel coding section 140, chirp signal generation section 150 for synchronization, time shift section 160, and waveform shaping synthesis section 170 are realized by processing circuits. The processing circuitry may be a processor and memory executing programs stored in the memory, or may be dedicated hardware. Processing circuitry is also called control circuitry.

FIG. 21 is a diagram showing a configuration example of processing circuit 90 when the processing circuit included in transmitting apparatus 100 according to the present embodiment is realized by processor 91 and memory 92. As shown in FIG. A processing circuit 90 shown in FIG. 21 is a control circuit and includes a processor 91 and a memory 92 . When the processing circuit 90 is composed of the processor 91 and the memory 92, each function of the processing circuit 90 is implemented by software, firmware, or a combination of software and firmware. Software or firmware is written as a program and stored in memory 92 . In the processing circuit 90, each function is realized by the processor 91 reading and executing the program stored in the memory 92. FIG. That is, the processing circuitry 90 includes a memory 92 for storing programs that result in the processing of the transmitting device 100 being executed. This program can also be said to be a program for causing the transmitting device 100 to execute each function realized by the processing circuit 90 . This program may be provided by a storage medium storing the program, or may be provided by other means such as a communication medium.

The above program comprises a first step in which spreading processing section 130 performs spreading processing by multiplying a modulated signal obtained by modulating a transmission bit sequence by a spreading sequence; A second step of performing channel coding on the processed signal based on the number of transmitting antennas, and a synchronization chirp signal generation unit 150 generating a synchronization chirp signal for timing synchronization in the receiving apparatus 200. A third step, and a fourth step in which the time shift unit 160 generates a block-unit signal obtained by cyclically time-shifting the synchronization chirp signal, and generates the same number of known sequences composed of signals of a plurality of blocks as the number of transmission antennas. Each of the steps and the waveform shaping/combining units 170, the number of which is the same as the number of transmitting antennas, is connected to different transmitting antennas 180, and combines the data sequence channel-encoded by the channel encoding unit 140 with the known sequence to obtain a different It can also be said that it is a program that causes the transmitting device 100 to execute the fifth step of generating a transmission signal and transmitting it from the transmission antenna 180 .

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

FIG. 22 is a diagram showing an example of processing circuit 93 when the processing circuit included in transmitting apparatus 100 according to the present embodiment is configured with dedicated hardware. The processing circuit 93 shown in FIG. 22 is, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or a combination thereof. thing applies. The processing circuit may be partly implemented by dedicated hardware and partly implemented by software or firmware. Thus, the processing circuitry may implement each of the functions described above through dedicated hardware, software, firmware, or a combination thereof.

It should be noted that the receiving device 200 is also implemented by a hardware configuration similar to that of the transmitting device 100 . In receiving apparatus 200, receiving antenna 210 is an antenna element. Bandwidth limiting section 220, timing synchronization section 230, despreading processing section 240, and demodulation section 250 are implemented by processing circuits. The processing circuitry may be a processor and memory executing programs stored in the memory, or may be dedicated hardware.

As described above, according to the present embodiment, in spread spectrum communication system 300, transmitting apparatus 100 divides and shortens a known sequence for obtaining a desired power gain for blocks, which are division units. , a cyclic time shift is added in units of blocks as transmission processing, and then transmitted. Receiving apparatus 200 performs cross-correlation processing using a known sequence before the cyclic time shift for each block, and combines a plurality of correlation value peaks obtained as processing results in consideration of the cyclic time shift. Accurate timing synchronization is performed by correlation processing only for the block length. As a result, when transmitting apparatus 100 transmits signals using a plurality of transmitting antennas 180 in a spread spectrum communication system, receiving apparatus 200 can achieve accurate timing synchronization while suppressing an increase in circuit scale for timing synchronization processing. It can be carried out.

The configurations shown in the above embodiments are only examples, and can be combined with other known techniques, or can be combined with other embodiments, without departing from the scope of the invention. It is also possible to omit or change part of the configuration.

100 transmitter, 110 modulation unit, 120 chirp signal generation unit, 130 spreading processing unit, 140 transmission line coding unit, 150 chirp signal generation unit for synchronization, 160 time shift unit, 170-1, 170-2 waveform shaping synthesis unit , 180-1, 180-2 transmitting antenna, 200 receiving device, 210 receiving antenna, 220 band limiting unit, 230 timing synchronization unit, 231 correlation sequence generation unit, 232 correlation processing unit, 233 inter-block synthesis unit, 234 intra-block synthesis section, 235 peak detection section, 240 despreading processing section, 250 demodulation section, 300 spread spectrum communication system.

Claims (12)

A transmitting device that performs wireless communication with a receiving device in a spread spectrum communication system,
a spreading processing unit that performs spreading processing by multiplying a modulated signal obtained by modulating a transmission bit sequence by a spreading sequence;
a transmission line coding unit that performs transmission line coding on the signal spread by the spreading processing unit based on the number of transmission antennas;
a synchronization chirp signal generator for generating a synchronization chirp signal for timing synchronization in the receiving device;
a time shifter that generates a signal in units of blocks obtained by cyclically time-shifting the chirp signal for synchronization, and generates the same number of known sequences composed of signals of a plurality of blocks as the number of transmission antennas;
each of which is connected to a different transmission antenna and combines a data sequence channel-encoded by the channel encoding unit with the known sequence to generate a different transmission signal and transmit the transmission signal from the transmission antenna; a waveform shaping/synthesizing unit of the same number as the number of antennas;
A transmitting device comprising: The number of transmitting antennas is 2 or more,
The transmission signal transmitted from each transmission antenna includes the known sequence with a different cyclic time shift amount of the synchronization chirp signal.
2. The transmitter according to claim 1, characterized by: The known sequence is composed of a number of blocks equal to or greater than the number of transmission antennas, and the cyclic time shift amount of the synchronization chirp signal at the same block position differs for each transmission signal transmitted from each transmission antenna. The number of candidates for the cyclic time shift amount obtained by accumulating the shift amount is the same for each transmission signal.
3. The transmitter according to claim 2, characterized by: A receiving device that performs wireless communication with a transmitting device in a spread spectrum communication system,
a band limiting unit configured to band limit a received signal, which is a received signal transmitted from the transmitting device, and extract a signal of a desired band;
generating a correlation processing known sequence including all or part of a synchronization chirp signal for timing synchronization generated by the transmitting device, and performing correlation processing between the desired band signal and the correlation processing known sequence; a timing synchronizing unit that detects a correlation value peak from the correlation value obtained by performing the timing synchronization to specify the head position of the received frame included in the received signal;
A receiving device comprising: The timing synchronization unit combines the peak values obtained by the correlation processing between the blocks of the known sequence composed of a plurality of blocks of signals with different amounts of cyclic time shifts, and further combines within the blocks. Timing synchronization is performed by detecting peaks from
5. The receiving apparatus according to claim 4, characterized by: a transmitter according to any one of claims 1 to 3;
a receiving device according to claim 4 or 5;
A spread spectrum communication system comprising: A control circuit for controlling a transmitting device that performs wireless communication with a receiving device in a spread spectrum communication system,
Spreading processing for multiplying a modulated signal obtained by modulating a transmission bit sequence by a spreading sequence,
Transmission path coding based on the number of transmitting antennas for spread processed signals,
generating a synchronization chirp signal for timing synchronization in the receiving device;
generating a block unit signal obtained by cyclically time-shifting the synchronization chirp signal, and generating the same number of known sequences composed of signals of a plurality of blocks as the number of transmission antennas;
combining the channel-encoded data sequence and the known sequence to generate a different transmission signal and transmitting it from a transmission antenna;
A control circuit that causes the transmitting device to implement: A control circuit for controlling a receiving device that performs wireless communication with a transmitting device in a spread spectrum communication system,
band-limiting a received signal, which is a signal transmitted and received from the transmitting device, and extracting a signal in a desired band;
generating a correlation processing known sequence including all or part of a synchronization chirp signal for timing synchronization generated by the transmitting device, and performing correlation processing between the desired band signal and the correlation processing known sequence; Timing synchronization for detecting a correlation value peak from the correlation value obtained by and specifying the beginning position of the received frame included in the received signal;
A control circuit that causes the receiving device to implement: A storage medium storing a program for controlling a transmitting device that performs wireless communication with a receiving device in a spread spectrum communication system,
Said program
Spreading processing for multiplying a modulated signal obtained by modulating a transmission bit sequence by a spreading sequence,
Transmission path coding based on the number of transmitting antennas for spread processed signals,
generating a synchronization chirp signal for timing synchronization in the receiving device;
generating a block unit signal obtained by cyclically time-shifting the synchronization chirp signal, and generating the same number of known sequences composed of signals of a plurality of blocks as the number of transmission antennas;
combining the channel-encoded data sequence and the known sequence to generate a different transmission signal and transmitting it from a transmission antenna;
A storage medium characterized by causing the transmitting device to implement: A storage medium storing a program for controlling a receiving device that wirelessly communicates with a transmitting device in a spread spectrum communication system,
Said program
band-limiting a received signal, which is a signal transmitted and received from the transmitting device, and extracting a signal in a desired band;
generating a correlation processing known sequence including all or part of a synchronization chirp signal for timing synchronization generated by the transmitting device, and performing correlation processing between the desired band signal and the correlation processing known sequence; Timing synchronization for detecting a correlation value peak from the correlation value obtained by and specifying the beginning position of the received frame included in the received signal;
A storage medium characterized by causing the receiving device to implement: A transmission method for a transmitting device that performs wireless communication with a receiving device in a spread spectrum communication system,
a first step in which the spreading processing unit performs spreading processing by multiplying a modulated signal obtained by modulating a transmission bit sequence by a spreading sequence;
a second step in which a transmission line coding unit performs transmission line coding on the signal spread by the spreading processing unit based on the number of transmitting antennas;
a third step in which a synchronization chirp signal generator generates a synchronization chirp signal for timing synchronization in the receiving device;
a fourth step in which the time shift unit generates a signal in units of blocks obtained by cyclically time-shifting the chirp signal for synchronization, and generates the same number of known sequences composed of signals of a plurality of blocks as the number of transmission antennas;
Waveform shaping/synthesizing units of the same number as the number of transmitting antennas are connected to different transmitting antennas, and combine the data sequence channel-encoded by the channel encoding unit with the known sequence to generate different transmission signals. a fifth step of generating and transmitting from the transmit antenna;
A transmission method comprising: A receiving method for a receiving device that performs wireless communication with a transmitting device in a spread spectrum communication system,
a first step in which a band-limiting unit performs band-limiting on a received signal, which is a signal transmitted from the transmitting device and received, and extracts a signal in a desired band;
A timing synchronization unit generates a correlation processing known sequence including all or part of a synchronization chirp signal for timing synchronization generated by the transmitting device, and combines the signal of the desired band with the correlation processing known sequence. A second step of performing timing synchronization for detecting a correlation value peak from the correlation value obtained by performing the correlation processing of and specifying the head position of the received frame included in the received signal;
A receiving method characterized by comprising:

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