JPH10178412A - Spread spectrum communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure a sufficient transmitting distance by modulating an information signal by a spread spectrum system to modulate a wide band signal, transmitting it through a weak power radio and reproducing it by a receiver so as to narrow a space a transmission signal gives influence. SOLUTION: Transmission data id encoded by an error correcting encoder 2 so as to correct an error generated by communication between a transmitter 1 and a repeater 9 and converted to transmission data by a data conversion part 3. In addition, an exclusive OR circuit 4 obtains exclusive OR with a spreading PN code and a modulator 5 modulates it with the carrier wave of a local oscillator 7 and radiates it. The repeater 9 correlate-demodulates a received signal by means of an SAW matched filter 12 and a demodulator 13, decodes it by means of an error correcting decoder 14 and encodes it by an error correcting encoder 15 so as to correct an error between the repeater 9 and a receiver 22. After then, the signal is radiated by weak radio similarly to the transmitter. The receiver 2 demodulates an SAW matched filter 25 and a demodulator 26 and corrects an error generated by an error correcting decoder 27 to output.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication system for converting a digital signal such as data, video, audio or the like into a radio signal of a spread spectrum system for communication, and more particularly to a communication system for performing the communication by low power radio. Things.

[0002]

2. Description of the Related Art As a system for wirelessly communicating data, video, audio, and other signals, it is difficult to interfere with communication of other communication devices and electronic devices, and conversely, interference of communication of other communication devices and electronic devices. A spread-spectrum system that is less susceptible to noise is known. The spread spectrum method is a method of performing communication by spreading information of a digital signal to be communicated over a wide band using a pseudo noise code (PN code). The digital signal to be communicated is compared with a pseudo signal having a higher repetition rate. A direct spreading method in which spreading is performed by calculation with a noise code, and a frequency hopping method in which spreading is performed by switching the frequency of a carrier according to a pseudo noise code.

[0003] These spread spectrum techniques are based on wireless LA.
N, etc. For example, in Japan, a specific low-power radio (radio wave output of 10 mW or less) in the ISM band (2.471 to 2.497 GHz) is used for an order entry system in a printer server or a restaurant. Also, when the transmission power is 3 m away from the transmission point, 5
Applications in weak power wireless communication, which is defined to be equal to or less than 00 μV / m (correction of −5 dB), are also being advanced.
However, when using weak power wireless communication, the communicable distance is limited to a few meters at the maximum.

[0004] The prior art of wireless LAN is described, for example, in Ohmsha's "Easy-to-understand Wireless LAN" by Maeda and Kato (August 20, 1993).

[0005]

SUMMARY OF THE INVENTION In indoor wireless communication,
The frequency or PN code used by a communication device may overlap with another communication device. In order to prevent interference in such an environment, the space affected by the transmission signal of each communication device must be limited as small as possible. However, if the space affected by the transmission signal is restricted narrowly, the communicable distance of the communication device also decreases.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a spread spectrum communication system capable of reducing a space affected by a transmission signal and securing a sufficient transmission distance.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the present invention provides a method of generating a wideband signal by performing spread spectrum modulation on an information signal, and transmitting the wideband signal by weak power radio. A terminal, receiving the broadband signal transmitted from the transmitting unit, reproducing the information signal by performing demodulation of the spread spectrum method on the broadband signal, and performing modulation of the spread spectrum method on the reproduced information signal. A broadband signal is generated, a relay that transmits the wideband signal by weak power radio, a wideband signal transmitted from the relay is received, and the wideband signal is subjected to spread spectrum demodulation to perform the information processing. A spread spectrum communication system, comprising: a receiving terminal that reproduces a signal.

[0008] In the spread spectrum communication system according to the present invention, the space affected by the transmission signal is narrowed by performing communication using weak power radio, and a sufficient transmission distance is secured by using a repeater.

[0009]

Embodiments of the present invention will be described below.

FIG. 1 is a block diagram of a spread spectrum communication system according to an embodiment of the present invention. The spread spectrum communication system shown in FIG. 1 includes a transmitter 1, a repeater 9, and a receiver 22, and performs a direct spread spectrum spread spectrum communication. The transmitter 1 includes an error correction encoder 2, a data converter 3, an exclusive OR circuit 4, a modulator 5, a PN code generator 6, a local oscillator 7, and an antenna 8. The repeater 9 has an antenna 10, a band-pass filter (BPF) 11, a surface acoustic wave (SAW) matched filter 12, a demodulator 13, and an error correction decoder 14 as a reception function, and an error correction code as a transmission function. , A data converter 16, an exclusive OR circuit 17, a PN code generator 1
8, a modulator 19, a local oscillator 20, and an antenna 21. The receiver 22 includes an antenna 23, a BPF 24, a SAW
It comprises a matched filter 25, a demodulator 26, and an error correction decoder 27.

Next, the operation of the spread spectrum communication system shown in FIG. 1 will be described.

First, the operation of the transmitter 1 will be described.
In the transmitter 1, the transmission data is input to the error correction encoder 2, and the transmission data is encoded so that an error generated in the communication between the transmitter 1 and the repeater 9 can be corrected. The encoded data is converted by the data conversion unit 3 into DPSK (Differentially encoded phasesh) whose polarity is inverted corresponding to the data value “1”.
ift keying) is converted into transmission data of the modulation method. The exclusive OR circuit 4 outputs the converted transmission data and the PN
The exclusive OR with the spreading PN code generated by the code generator 6 is calculated. Here, since the spreading PN code changes in a time sufficiently shorter than the transmission data, the exclusive OR circuit 4
Is data obtained by spreading transmission data information over a wide band. The spread data is modulated by a modulator 5 using a carrier wave generated by a local oscillator 7 in BPSK (Bi-phase shift).
keying) and is radiated from the antenna 8 by radio waves. Here, the modulator 5 amplifies the transmission signal so that the power of the radiated radio wave becomes 500 μV / m (correction of −5 dB) or less at a distance of 3 m from the transmission point. In addition, when applied to the weak power radio in Japan, the carrier frequency of the local oscillator 7 is, for example, 300 MHz, 275 MHz.
Any of z, 250 MHz and 225 MHz is used.

Next, the repeater 9 will be described. The radio wave radiated from the antenna 8 of the transmitter 1 is incident on the antenna 10 in the repeater 9, and the BPF 11 removes noise components in unnecessary bands to extract a main lobe signal. This main lobe signal is supplied to the SAW matched filter 1
In step 2, correlation demodulation is performed. The SAW matched filter 1
2 is designed corresponding to a PN code and a carrier frequency used in the transmitter 1. The correlation-demodulated signal is subjected to DPSK demodulation by a demodulator 13 and further to an error correction decoder 1
By decoding at 4, the data error caused by the communication between the transmitter 1 and the repeater 9 is corrected. The data decoded by the error correction decoder 14 is transmitted by the error correction encoder 15 to the relay 9.
The receiver 22 is coded so that an error that may occur in the communication with the receiver 22 can be corrected. Then, the coded data is converted into data corresponding to the DPSK modulation method by the data conversion unit 16, and the exclusive OR circuit 17 performs exclusive exclusion with the spreading PN code generated by the PN code generator 18. The logical sum is taken and the information is diffused. The spread data is BPSK-modulated by the modulator 19 with the carrier generated by the local oscillator 20, and is radiated from the antenna 21 as a weak radio wave having the same transmission power as that of the transmitter 1. Here, the carrier frequency of the local oscillator 20 is selected so that the reception signal and the transmission signal of the repeater 9 do not interfere with each other. When applied to Japanese weak power radio, the carrier frequency of the local oscillator 20 is, for example, 300 MHz, 275 MHz,
Any one of 250 MHz and 225 MHz except the carrier frequency of the transmitter 1 is used. In this way, by making the carrier frequency (for example, 300 MHz) of the transmitter 1 and the carrier frequency (for example, 250 MHz) of the repeater 9 different from each other, the radiated radio wave of the repeater 9 interferes with the receiving unit of the repeater 9 itself. I try not to.

Next, the receiver 22 will be described. In the receiver 22, the signal radiated from the antenna 21 of the repeater 9 is incident on the antenna 23, the noise component in the unnecessary band is removed by the BPF 24, and the main lobe signal is extracted. This main lobe signal is an SA designed for a PN code and a carrier frequency used in transmission of the repeater 9.
Correlation demodulation is performed by the W matched filter 25, and further DPSK demodulation is performed by the demodulator 26. The DPSK-demodulated data is decoded by an error correction decoder 27, and after correcting a data error caused by communication between the repeater 9 and the receiver 22, the data is output as received data.

As described above, in the present embodiment in which the weak power wireless communication of the direct spreading method is performed, the transmission distance (between the transmitter 1 and the receiver 22) is at most twice as long as when the repeater 9 is not used.
Can be secured.

Next, a second embodiment of the present invention will be described.

A spread spectrum communication system according to a second embodiment of the present invention is obtained by disposing N repeaters (N is an integer of 2 or more) in series in the first embodiment. In this configuration, the transmission signal of the transmitter is sequentially relayed by N repeaters and reaches the receiver. By arranging N repeaters in series, in the second embodiment, a maximum transmission distance of N + 1 times can be ensured as compared with the case where the repeater 9 is not used. In the spread spectrum communication system, a carrier frequency is assigned to each repeater 9 so that the transmission signal and the reception signal do not interfere with each other. The carrier frequencies to be assigned are different such that the carrier frequency of the K-th repeater is A, the carrier frequency of the K + 1-th repeater is B, and the carrier frequency of the K + 2th repeater is C. The transmission wave of one's own does not interfere with the receiving part. However, 1
The carrier frequencies (for example, C and A) of each of the repeaters arranged with two or more repeaters interposed therebetween may be the same. In addition, when applied to the weak power radio in Japan, the carrier frequency is set to 300 MHz, 275 MHz,
And 225 MHz.

A third embodiment of the present invention will be described below.

FIG. 2 is a block diagram of a spread spectrum communication system according to a third embodiment of the present invention. The spread spectrum communication system of the present embodiment also includes a transmitter 1, a repeater 9, and a receiver 22, but differs from the first embodiment in that a frequency hopping method is used as a spread method. In FIG. 2, a transmitter 1 includes an error correction encoder 2, a modulator 5, a spread code generator 30, a frequency synthesizer 31, and an antenna 8. The repeater 9 includes an antenna 10, a BPF 11, a mixer 34,
BPF 35, synchronization circuit 36, spreading code generator 37, frequency synthesizer 38, demodulator 13, error correction decoder 1
, A transmission function, an error correction encoder 15, a modulator 19, a spread code generator 40, a frequency synthesizer 4
1. It has an antenna 21. The receiver 22 includes the antenna 2
3, BPF24, mixer 44, BPF45, synchronization circuit 4
6, a spread code generator 47, a frequency synthesizer 48, a demodulator 26, and an error correction decoder 27. The antenna, the modulator, the demodulator, the error correction encoder, and the error correction decoder in FIG. 2 have the same function as the circuit of the same code in FIG.

Next, the operation of the spread spectrum communication system shown in FIG. 2 will be described.

First, the operation of the transmitter 1 will be described.
In the transmitter 1, input transmission data is encoded by an error correction encoder 2 as in the first embodiment.
The modulator 5 performs DPSK modulation. In parallel with this, the spreading code generator 30 generates a multi-level signal sequence called a hopping pattern. According to the signal sequence, the frequency synthesizer 31 temporally switches the generated carrier frequency in a specific pattern, and converts the data modulated by the modulator 5 into a radio frequency signal. Thereby, the modulation data of the modulator 5 which is a narrow band signal is converted into a wide band signal occupying a specific wide frequency band as a time average,
It is radiated from the antenna 8 at the transmission power of the weak power wireless communication. Note that, when applied to the weak power radio in Japan, the center frequency of this wideband signal is, for example, 300 MHz, 275
MHz, 250 MHz, or 225 MHz.

Next, the repeater 9 will be described. The signal radiated from the antenna 8 of the transmitter 1 is incident on the antenna 10, and after the noise component in the unnecessary band is removed by the BPF 11, the signal is input to the mixer 34. In parallel with this, the spreading code generator 37 generates the same hopping pattern in synchronization with the spreading code generator 30 in the transmitter 1. The frequency synthesizer 38 generates a demodulation carrier whose frequency changes according to the hopping pattern, and outputs the carrier to the mixer 34. The output signal of the BPF 11 is despread by being multiplied by a carrier for demodulation by the mixer 34, and is converted into a narrowband signal having the same bandwidth as the signal before spreading. This narrow band signal is input to the synchronization circuit 36 and the demodulator 13 after the noise component of the unnecessary band is removed by the BPF 35. The synchronization circuit 36 performs synchronization acquisition and synchronization tracking of the received signal based on the input narrowband signal, and generates a timing signal. With this timing signal, the spreading code generator 37 can generate a hopping pattern with a phase that matches the received signal. Specifically, the synchronization circuit 36 first shifts the phase of the hopping pattern generated by the spread code generator 37 by using, for example, a serial search method, and detects a phase (synchronization point) matched with the received signal. To perform synchronization acquisition,
Thereafter, synchronization tracking is performed using, for example, a delay lock loop to maintain a synchronization point. On the other hand, the narrow band signal input to the demodulator 13 is subjected to BPSK demodulation, and a data error is corrected by the error correction decoder 14.

The data after error correction is encoded by the error correction encoder 15, DPSK-modulated by the modulator 19, and input to the frequency synthesizer 41. The frequency synthesizer 41 converts the narrowband signal from the modulator 19 into a radio frequency by temporally switching the carrier frequency according to the hopping pattern generated by the spreading code generator 40. Thereby, the narrow band signal from the modulator 19 is converted into a wide band signal occupying a specific wide frequency band as a time average, and is radiated from the antenna 21 with the transmission power of the weak power wireless communication. Here, the frequency synthesizer 41
Are selected so that the received signal and the transmitted signal of the repeater 9 do not interfere with each other. When applied to Japanese weak power wireless communication, the center frequency of this broadband signal is, for example, 300 MHz, 27 MHz.
5MHz, 250MHz, 225MHz, transmitter 1
At any frequency except for the center frequency of the wideband signal. As described above, by making the center frequencies of the wideband signals transmitted and received by the repeater 9 different, in the present embodiment, the radiated radio waves of the repeater 9 do not interfere with the reception unit of the repeater 9 itself.

Next, the receiver 22 will be described. In the receiver 22, the signal radiated from the antenna 21 of the repeater 9 is incident on the antenna 23, and after the noise component in the unnecessary band is removed by the BPF 24, the signal is input to the mixer 44. In parallel with this, the spreading code generator 47
The same hopping pattern is generated in synchronism with the spreading code generator 40 in. The frequency synthesizer 48 generates a demodulation carrier whose frequency changes according to the hopping pattern and outputs the generated carrier to the mixer 44. The output signal of the BPF 24 is despread by being multiplied by a carrier for demodulation by the mixer 44, and is converted into a narrowband signal having the same bandwidth and the same content as the signal before spreading. This narrow band signal is
After the noise component of the unnecessary band is removed at 45, the synchronization circuit 4
6 and input to the demodulator 26. The synchronization circuit 46 performs synchronization acquisition of the received signal using, for example, a serial search method on the basis of the input narrowband signal, performs synchronization tracking using a delay lock loop, and generates a timing signal. With this timing signal, the spread code generator 47 generates a hopping pattern with a phase matched with the received signal in synchronization with the spread code generator 40 of the repeater 9. On the other hand, demodulator 1
The narrowband signal input to 3 is subjected to BPSK demodulation, and an error correction decoder 14 corrects a data error.

As described above, in the present embodiment for performing the low-power radio communication of the frequency hopping method, it is possible to secure a maximum transmission distance twice as long as the case where the repeater 9 is not used.

Next, a fourth embodiment of the present invention will be described.

A spread spectrum communication system according to a fourth embodiment of the present invention is obtained by disposing N repeaters (N is an integer of 2 or more) in series in the third embodiment. By arranging N repeaters in series, in the fourth embodiment, it is possible to secure a maximum transmission distance of N + 1 times as compared with a case where no repeater is used. In the present embodiment, the center frequency of the wideband signal is determined so that the wideband signals transmitted by the repeaters do not interfere with each other. The center frequency of the wideband signal transmitted by the Kth repeater is A, the center frequency of the wideband signal transmitted by the (K + 1) th repeater is B, and the center frequency of the wideband signal transmitted by the (K + 2) th repeater is C. Thus, the center frequency is made different so that the transmission wave of the own repeater does not disturb the reception of the own repeater in each repeater. However, the center frequencies (for example, C and A) of the wideband signals transmitted by each of the repeaters arranged with one or more repeaters interposed therebetween may be the same. In addition, when applied to weak power wireless communication in Japan, the center frequency of a wideband signal is set to, for example, 300 MHz according to the above conditions.
275 MHz, 250 MHz, and 225 MHz are selected and assigned.

A fifth embodiment of the present invention will be described below.

FIG. 3 is a block diagram of a spread spectrum communication system according to a fifth embodiment of the present invention. The spread spectrum communication system shown in FIG. 3 has a configuration in which the RAKE receiver is arranged in the repeater 9 in the configuration of the first embodiment (FIG. 1). In FIG. 3, the RAKE receiver 49
Is inserted between the antenna 10 and the BPF 11.
Other configurations and operations of the present embodiment include the local oscillator 7,
This is the same as the first embodiment except for the local oscillator 20.

In the first embodiment, the carrier frequencies of the local oscillator 7 and the local oscillator 20 of the repeater 9 are different from each other, but in the present embodiment of FIG. 3, the carrier frequencies of the local oscillator 7 and the local oscillator 20 are changed. It is the same. In this case, the antenna 10 of the repeater 9 receives a signal having the same frequency and a phase shift from both the antenna 8 of the transmitter 1 and the transmission antenna 21 of the repeater. The RAKE receiver 49 performs an operation of extracting only the signal of the radiated radio wave of the transmitter 1 from the multiplex wave, and outputs the extracted signal to the BPF 11.
Output to For this reason, the radiated radio wave of the
It does not interfere with its own receiver.

As described above, in the present embodiment, the transmission carrier frequency of the transmitter and the repeater can be made the same by using the RAKE receiver. Further, by arranging N repeaters 9 (N is an integer of 2 or more) in series between the transmitter 1 and the receiver 22, a maximum transmission distance of N + 1 times is secured as compared with the case where no repeater is used. It is also possible.

A sixth embodiment of the present invention will be described below.

FIG. 4 is a block diagram of a spread spectrum communication system according to a sixth embodiment of the present invention. The spread spectrum communication system of FIG. 4 has a configuration in which the RAKE receiver is arranged in the repeater 9 in the configuration of the third embodiment (FIG. 2). In FIG. 4, the RAKE receiver 49
Is inserted between the antenna 10 and the BPF 11 in the repeater 9. Other configurations and operations of this embodiment are the same as those of the third embodiment except for the spreading code generator 30 and the spreading code generator 40.

In the third embodiment, the center frequency of the frequency band occupied by the transmission signal after the frequency hopping modulation is different between the transmitter 1 and the repeater 9, but in the present embodiment shown in FIG. 1 and each hopping pattern generated in the repeater 9, and the center frequency of the frequency band occupied by each transmission signal is the same. In this case, the antenna 10
In this case, signals having the same frequency and a phase shift are received from both the antenna 8 of the transmitter and the transmission antenna 21 of the repeater. The RAKE receiver 49 performs an operation of extracting only the signal of the radio wave radiated from the transmitter 1 from the multiplex wave, and outputs the extracted signal to the BPF 11. Thereby, the radiated radio wave of the repeater 9 does not interfere with the reception of the repeater 9 itself.

As described above, in this embodiment, the use of the RAKE receiver makes it possible to make the hopping pattern and the center frequency of the transmission signal identical between the transmitter and the repeater. By arranging N repeaters 9 (N is an integer of 2 or more) in series between the transmitter 1 and the receiver 22, a transmission distance up to N + 1 times can be secured as compared with a case where no repeater is used. It is possible.

The seventh embodiment of the present invention will be described below.

FIG. 5 is a block diagram of a spread spectrum communication system according to a seventh embodiment of the present invention. The spread spectrum communication system of FIG. 5 is obtained by adding a configuration for obtaining a diversity effect to the receiving unit of the repeater 9 in the configuration of the first embodiment (FIG. 1). The configuration to be added is an antenna 51, a phase shifter 52, and an adder 53. Other configurations and operations of the present embodiment are the same as those of the first embodiment except for the local oscillator 7 and the local oscillator 20. In this embodiment, the local oscillator 7 and the local oscillator 20 have the same carrier frequency. Further, the antenna 51 and the antenna 10 of the repeater 9 are arranged so as to have a spatial distance so that the phases of signals to be received are shifted from each other by π / 2.

The signal radiated from the antenna 8 of the transmitter 1 is received by the antenna 51 and input to the phase shifter 52. This input signal is input to the adder 53 after the phase is delayed by π / 2 in the phase shifter 52. The signal radiated from the antenna 8 is also received by the antenna 10 at a phase delayed by π / 2 with respect to the antenna 51, and is input to the adder 52. For this reason, the broadband signal transmitted from the antenna 8 of the transmitter 1 is input to the adder 53 as two signals having the same phase, and the signal component is emphasized by the addition. On the other hand, the signal radiated from the antenna 21 of the repeater 9 is also received by the antennas 51 and 10, and the same processing is performed. However, contrary to the above, this signal is received by the antenna 51 with a phase delayed by π / 2 with respect to the reception by the antenna 10. For this reason, the broadband signal transmitted from the antenna 21 of the repeater 9 is input to the adder 53 as two signals having phases opposite to each other (phase difference π), and the signal component is canceled by the addition. Become. The output of the adder 53, which is a signal in which the components of the signal radiated from the antenna 8 of the transmitter 1 are emphasized and the components of the signal radiated from the antenna 21 of the repeater 9 are canceled, is input to the BPF 11.

As described above, in the present embodiment, the transmission carrier frequency of the transmitter and the repeater can be made the same by using the diversity receiving technique. Further, by arranging N repeaters 9 (N is an integer of 2 or more) in series between the transmitter 1 and the receiver 22, a maximum transmission distance of N + 1 times is secured as compared with the case where no repeater is used. It is also possible.

An eighth embodiment of the present invention will be described below.

FIG. 6 is a block diagram of a spread spectrum communication system according to an eighth embodiment of the present invention. The spread spectrum communication system of FIG. 6 is obtained by adding a configuration for obtaining a diversity effect to the receiving unit of the repeater 9 in the configuration of the third embodiment (FIG. 2). The configuration to be added is an antenna 51, a phase shifter 52, and an adder 53. These configurations have the same functions as those described in the seventh embodiment. Other configurations and operations of the present embodiment in FIG. 6 are the same as those of the third embodiment except for the local oscillator 7 and the local oscillator 20. In the present embodiment of FIG. 6, each hopping pattern generated in the transmitter 1 and the repeater 9 and the center frequency of each broadband signal are the same. The antennas 51 and 10 of the repeater are arranged with a spatial distance so that the phases of the signals to be received are shifted from each other by π / 2.

The signal radiated from the antenna 8 of the transmitter 1 is received by the antenna 51 and input to the phase shifter 52. This input signal is input to the adder 53 after the phase is delayed by π / 2 in the phase shifter 52. The signal radiated from the antenna 8 is also received by the antenna 10 at a phase delayed by π / 2 with respect to the antenna 51, and is input to the adder 52. For this reason, the broadband signal transmitted from the antenna 8 of the transmitter 1 is input to the adder 53 as two signals having the same phase, and the signal component is emphasized by the addition. On the other hand, the signal radiated from the antenna 21 of the repeater 9 is also received by the antennas 51 and 10, and the same processing is performed. However, contrary to the above, this signal is received by the antenna 51 with a phase delayed by π / 2 with respect to the reception by the antenna 10. For this reason, the broadband signal transmitted from the antenna 21 of the repeater 9 is input to the adder 53 as two signals having phases opposite to each other (phase difference π), and the signal component is canceled by the addition. Become. The output of the adder 53, which is a signal in which the components of the signal radiated from the antenna 8 of the transmitter 1 are emphasized and the components of the signal radiated from the antenna 21 of the repeater 9 are canceled, is input to the BPF 11.

As described above, in the present embodiment, the hopping pattern in the transmitter and the repeater and the center frequency of the wideband signal can be made the same by using the diversity reception technique. Also, a transmitter 1 and a receiver 2
By arranging N repeaters 9 in series (N is an integer of 2 or more) between the two, at most N + 1 compared to the case where no repeater is used
It is also possible to secure twice the transmission distance.

The ninth embodiment of the present invention will be described below.

FIG. 7 is a block diagram of a spread spectrum communication system according to the ninth embodiment of the present invention. The spread spectrum communication system of FIG. 7 has a configuration in which the delay unit 57, the attenuator 58, and the adder 59 are added to the repeater 9 in the configuration of the first embodiment (FIG. 1). Other configurations and operations of the present embodiment of FIG. 7 are the same as those of the first embodiment except for the local oscillator 7 and the local oscillator 20.

In the spread spectrum communication system of this embodiment, the local oscillator 7 and the local oscillator 20 have the same carrier frequency. For this reason, in the repeater 9, the signal radiated from the antenna 21 becomes a strong jamming radio wave for the signal to be received radiated from the antenna 8 of the transmitter 1. A delay unit 57, an attenuator 58, and an adder 59 are provided to cancel the jamming radio wave.

Here, it is assumed that the delay time until the signal radiated from the antenna 21 is received by the antenna 10 is τ1, and the delay time of the signal at the attenuator 57 is τ2. In the repeater 9, the output signal of the modulator 19 is
And is also input to the delay unit 57 to be delayed by the delay time τ1−τ2. The attenuator 58 is radiated from the antenna 21 and is transmitted through the antenna 10 to the adder 59.
The signal output from the delay unit 57 is attenuated so that the signal level becomes the same as the signal level of the signal that has reached. The output signal of the attenuator 58 is input to the adder 59, the polarity of which is inverted, and then added to the signal received by the antenna 10. As a result, the components of the signal radiated from the antenna 21 and received by the antenna 10 are canceled by the adder 59.

As described above, in this embodiment, the transmission carrier frequencies of the transmitter 1 and the repeater 9 can be the same. Further, by arranging N repeaters 9 (N is an integer of 2 or more) in series between the transmitter 1 and the receiver 22, a maximum transmission distance of N + 1 times is secured as compared with the case where no repeater is used. It is also possible.

The tenth embodiment of the present invention will be described below.

FIG. 8 is a block diagram of a spread spectrum communication system according to the tenth embodiment of the present invention. FIG.
In the spread spectrum communication system of the third embodiment, a delay unit 57, an attenuator 58, and an adder 59 are added to the repeater 9 in the configuration of the third embodiment (FIG. 2). The other configuration and operation of the present embodiment of FIG.
0, except that the spreading code generator 40 is the same as the third embodiment.

In the third embodiment, the center frequency of the wide band signal after the frequency hopping modulation is made different between the transmitter 1 and the repeater 9, but in the present embodiment of FIG. The center frequency of each hopping pattern generated in the above and each broadband signal are the same. For this reason,
In the repeater 9, the signal radiated from the antenna 21 becomes a strong jamming wave for the signal to be received radiated from the antenna 8 of the transmitter 1. A delay unit 57, an attenuator 58, and an adder 59 are provided to cancel the jamming radio wave.

Here, the delay time until the signal radiated from the antenna 21 is received by the antenna 10 is τ1, and the delay time of the signal at the attenuator 57 is τ2. In the repeater 9, the output signal of the modulator 19 is
And is also input to the delay unit 57 to be delayed by the delay time τ1−τ2. The attenuator 58 is radiated from the antenna 21 and is transmitted through the antenna 10 to the adder 59.
The signal output from the delay unit 57 is attenuated so that the signal level becomes the same as the signal level of the signal that has reached. The output signal of the attenuator 58 is input to the adder 59, the polarity of which is inverted, and then added to the signal received by the antenna 10. As a result, the components of the signal radiated from the antenna 21 and received by the antenna 10 are canceled by the adder 59.

As described above, in the present embodiment, the hopping pattern in the transmitter and the repeater and the center frequency of the wideband signal can be made the same to perform the weak power wireless communication of the frequency hopping method. In addition, by arranging N repeaters 9 (N is an integer of 2 or more) in series between the transmitter 1 and the receiver 22, the maximum number of N +
It is also possible to secure a transmission distance that is one time.

The eleventh embodiment of the present invention will be described below.

FIG. 9 schematically shows a configuration of a spread spectrum communication system according to an eleventh embodiment of the present invention. The spread spectrum communication system of FIG. 9 includes a transceiver 61 and a transceiver 62 that communicate with each other by half-duplex communication.
And a repeater 9. Each transceiver 61
(62) is a transmitter 1 and a receiver 22 for performing low power wireless communication of the direct spreading system, and a transmission / reception switch 6
3 (64) and an antenna 8 (23). The transmission / reception switches 63 and 64 perform an operation of connecting the transmitter 1 to the antenna at the time of transmission and connecting the receiver and the antenna at the time of reception. The transmitter 1, the antenna 8, the receiver 22 shown in FIG.
Antenna 10, repeater 9, antenna 21, antenna 23
Are the same as those used in the first embodiment.

Next, the operation of this embodiment will be described.

First, a case where a signal is transmitted from the transceiver 61 to the transceiver 62 will be described. In the transceiver 61,
The input transmission data is input to the transmitter 1 and is subjected to direct spread spectrum spread modulation. The wideband signal modulated by the transmitter 1 is input to the transmission / reception switch 60. At the time of transmission, the transmission / reception switch 60 connects the output of the transmitter 1 to the antenna 8, so that the modulated broadband signal is radiated from the antenna 8. In the repeater 9, the signal radiated from the transceiver 61 is received by the antenna 10, and the received signal is demodulated and re-modulated (direct spread spectrum spread modulation).
And radiates from the antenna 21. The signal radiated from the antenna 21 enters the antenna 23 in the transceiver 62 and is input to the transmission / reception switch 64. Since the transmission / reception switch 64 connects the antenna 23 and the receiver 22 at the time of reception, a signal received by the antenna 23 is input to the receiver 22. The receiver 22 demodulates the input wideband signal and outputs received data obtained by the demodulation.

Next, a case where a signal is transmitted from the transceiver 62 to the transceiver 61 will be described. In the transceiver 62,
Transmission data is input to the transmitter 1 and is subjected to direct spread spectrum spread spectrum modulation. The wideband signal modulated by the transmitter 1 is input to the transmission / reception switch 64. At the time of transmission, the transmission / reception switch 64 connects the transmitter 1 and the antenna 23, so that the modulated broadband signal is radiated from the antenna 23. In the repeater 9, the signal radiated from the transceiver 61 is received by the antenna 10, and the received signal is demodulated, re-modulated (direct spread spectrum spread modulation), and radiated from the antenna 21. The signal radiated from the repeater 9 enters the antenna 8 in the transceiver 61 and is input to the transmission / reception switch 63. Transmission / reception switch 63 during reception
Connects the antenna 8 and the receiver 22, the signal received by the antenna 8 is input to the receiver 22. The receiver 22 demodulates the input wideband signal and outputs received data obtained by the demodulation.

As described above, in the present embodiment, the spread spectrum communication of the direct spread system using a weak radio wave can be performed in half duplex. Further, by arranging N repeaters 9 (N is an integer of 2 or more) in series between the transmitter 1 and the receiver 22, a maximum transmission distance of N + 1 times is secured as compared with the case where no repeater is used. It is also possible. Further, by providing two functions of the repeater 9, full-duplex communication can be performed.

Next, a twelfth embodiment of the present invention will be described.

The spread spectrum communication system according to the twelfth embodiment of the present invention has the same configuration as that of the eleventh embodiment described above in the third embodiment (FIG. 2).
The transmitter 1, the receiver 22, and the repeater 9 are used. That is, in the present embodiment, the transceiver and the repeater 9 perform bidirectional weak power wireless communication using the frequency hopping method as the modulation method. Further, by arranging N repeaters 9 (N is an integer of 2 or more) in series between the transmitter 1 and the receiver 22, a maximum transmission distance of N + 1 times is secured as compared with the case where no repeater is used. It is also possible. Further, by providing two functions of the repeater 9, full-duplex communication can be performed.

[0062]

According to the present invention, it is possible to provide a spread spectrum communication system capable of reducing a space affected by a transmission signal and securing a sufficient transmission distance.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a spread spectrum apparatus according to the present invention.

FIG. 2 is a block diagram showing another embodiment of the spread spectrum apparatus of the present invention.

FIG. 3 is a block diagram showing another embodiment of the spread spectrum apparatus of the present invention.

FIG. 4 is a block diagram showing another embodiment of the spread spectrum apparatus of the present invention.

FIG. 5 is a block diagram showing another embodiment of the spread spectrum apparatus of the present invention.

FIG. 6 is a block diagram showing another embodiment of the spread spectrum apparatus of the present invention.

FIG. 7 is a block diagram showing another embodiment of the spread spectrum apparatus of the present invention.

FIG. 8 is a block diagram showing another embodiment of the spread spectrum apparatus of the present invention.

FIG. 9 is a block diagram showing another embodiment of the spread spectrum apparatus of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Transmitter 2 ... Error correction encoder 3 ... Data conversion part 4 ... Exclusive OR circuit 5 ... Modulator 6 ... PN code generator 7 ... Local oscillator 8 ... Antenna 9 ... Repeater 10 ... Antenna 11 ... Band Pass filter 12 SAW matched filter 13 Demodulator 14 Error correction decoder 15 Error correction encoder 16 Data conversion unit 17 Exclusive OR circuit 18 PN code generator 19 Modulator 20 Local unit Oscillator 21 Antenna 22 Receiver 23 Antenna 24 Bandpass Filter 25 SAW Matched Filter 26 Demodulator 27 Error Correction Decoder 30 Spread Code Generator 31 Frequency Synthesizer 34 Mixer 35 Bandpass Filter 36 synchronization circuit 37 spreading code generator 38 frequency synthesizer 40 spreading code generator 41 frequency synthesizer DESCRIPTION OF SYMBOLS 4 ... Mixer 45 ... Band-pass filter 46 ... Synchronization circuit 47 ... Spreading code generator 48 ... Frequency synthesizer 49 ... RAKE receiver 51 ... Antenna 52 ... Phase shifter 53 ... Adder 57 ... Delayer 58 ... Attenuator 59 ... Addition Device 61 ... Transceiver 62 ... Transceiver 63 ... Transceiver switch 64 ... Transceiver switch

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takashi Shiba 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Inside the Multimedia System Development Division of Hitachi, Ltd. 292, Hitachi, Ltd. Multimedia System Development Division, Hitachi, Ltd.

Claims (9)

[Claims] 1. A transmitting terminal for generating a wideband signal by performing spread spectrum modulation on an information signal, transmitting the wideband signal by weak power radio, and receiving a wideband signal transmitted from the transmitting unit. Reproducing the information signal by performing spread spectrum demodulation on the wideband signal, generating a wideband signal by performing spread spectrum modulation on the reproduced information signal, and transmitting the wideband signal by weak power radio. A spreader that transmits, and a receiving terminal that receives the wideband signal transmitted from the repeater and reproduces the information signal by performing demodulation of a spread spectrum method on the wideband signal. Communications system. 2. A transmitter for generating a wideband signal by performing spread spectrum modulation on an information signal and transmitting the wideband signal by weak power radio, and transmitting a wideband signal modulated by spread spectrum wirelessly. And a receiving unit that reproduces the information signal before modulation by performing demodulation of the spread spectrum method on the wideband signal, and selectively performs one of the function of the transmitting unit and the function of the receiving unit. A plurality of transmission / reception terminals each having transmission / reception switching means effective for receiving a wideband signal transmitted from a transmission unit of the one transmission / reception terminal, and performing demodulation of a spread spectrum system on the wideband signal. Regenerates the information signal, generates a wideband signal by performing spread spectrum modulation on the reproduced information signal, and transmits the wideband signal to another transmitting / receiving terminal by weak power radio. A plurality of transmission / reception terminals that perform half-duplex communication with each other. 3. The spread spectrum communication system according to claim 1, further comprising a plurality of said repeaters, wherein said plurality of repeaters sequentially relay communication between said transmitting terminal and said receiving terminal. A spread spectrum communication system, comprising: 4. The spread spectrum communication system according to claim 1, wherein the repeater includes RAKE receiving means for reducing a component of a transmission signal of the repeater included in a wideband signal received by the repeater. A spread spectrum communication system characterized by the above-mentioned. 5. The spread spectrum communication system according to claim 1, wherein the repeater includes diversity receiving means for reducing a component of a transmission signal of the repeater included in a signal received by the repeater. A spread spectrum communication system, comprising: 6. The spread spectrum communication system according to claim 5, wherein the diversity receiving means includes two receiving antennas,
A phase shifter for delaying the phase of the reception signal of one of the receiving antennas, and a signal to be demodulated by adding the reception signal of the other reception antenna and the signal whose phase has been delayed by the phase shifter. The two signals added by the adder have a transmission signal of the transmitting terminal as a component in phase with each other, and have a transmission signal of the own repeater as a component with a phase opposite to each other. Thus, the arrangement of the receiving antenna and the amount of phase shift of the phase shifter are determined. 7. The spread spectrum communication system according to claim 1, wherein the repeater delays a transmission signal of the own repeater branched in the own repeater, and the delayed signal. An attenuator that attenuates the signal level of the signal, and an adder that adds the attenuated signal and the received signal of the own repeater to generate a signal to be demodulated. A spread spectrum communication system, wherein a delay time of the delay unit and an amount of attenuation of the attenuator are determined so that is canceled. 8. The spread spectrum communication system according to claim 1, wherein the transmitting terminal includes an error correction coding unit, a BPSK modulation unit, and a direct spread spectrum modulation unit using a pseudo noise (PN) code. The repeater includes a direct spectrum despreading unit using a PN code, a BPSK demodulation unit, an error correction decoding unit,
An error correction encoding unit, a BPSK modulation unit, and a direct spread spectrum modulation unit using a PN code, wherein the receiving terminal includes a direct spectrum despreading unit using a PN code, a BPSK demodulation unit, and an error correction decoding unit. A spread spectrum communication system, comprising: 9. The spread spectrum communication system according to claim 1, wherein the transmitting terminal includes an error correction coding unit, a BPSK modulation unit, and a frequency hopping spread spectrum modulation unit. Frequency hopping spectrum despreading means, BPSK demodulation means, error correction decoding means, error correction coding means, BPSK modulation means, frequency hopping spread spectrum modulation means, A spread spectrum communication system comprising hopping spectrum despreading means, BPSK demodulation means, and error correction decoding means.