WO2017090467A1

WO2017090467A1 - Communication device and communication method

Info

Publication number: WO2017090467A1
Application number: PCT/JP2016/083554
Authority: WO
Inventors: 光彦北島; 智広糸賀
Original assignee: 株式会社日立国際電気
Priority date: 2015-11-25
Filing date: 2016-11-11
Publication date: 2017-06-01
Also published as: JP6497825B2; JPWO2017090467A1

Abstract

The purpose of the present invention is to provide a communication device capable of a frequency hopping communication system which ensures that there is no overlap of frequencies at the same time in order to, even if two waves of a transmission frequency including a subcarrier (that are disposed to have an orthogonal relation therebetween) are close to each other, eliminate mutual interference by a bandwidth and the orthogonality of subcarriers corresponding to the bandwidth. This communication device performs frequency hopping communication and is provided with a wireless unit and a modulation/demodulation unit, the communication device being characterized in that the wireless unit comprises an antenna, a sharing unit, a directional coupling unit, a filter unit, an amplification unit, a synthesis unit, and a division unit, the modulation/demodulation unit comprises an OFDM modulation/demodulation unit, an orthogonal modulation unit, an orthogonal demodulation unit, a local transmission unit, and a reference clock generation unit, and the reference clock generation unit supplies a reference clock to the OFDM modulation/demodulation unit and the local transmission unit.

Description

Communication apparatus and communication method

The present invention relates to a communication device and a communication method.

Conventionally, in a communication system composed of communication devices using different frequencies, when transmitting simultaneously, in order to avoid mutual interference, when the two waves are particularly close to each other, the original characteristics can be obtained by mutual interference. I can't. Therefore, a transmission filter is used for the transmission output.
In addition, when performing frequency hopping communication, etc., in these communication systems, it is necessary to provide filters with strict performance in the transmission system. In addition, when performing frequency hopping communication, filter banks with different center frequencies are required. In addition, it is difficult to improve the hopping speed, which increases the size of the apparatus.

As a prior art document, for example, Patent Document 1 discloses an invention for reducing burst data errors caused by switching of a radio modulation frequency in a frequency hopping method.

JP 2003-229789 A

The object of the present invention is to adapt the bandwidth and the power per subcarrier even if two waves of the transmission frequency including the subcarrier are close to each other, reduce mutual interference, and use frequency for anti-interception and anti-jamming. In order to eliminate mutual interference in a frequency hopping scheme in which communication is performed by changing the frequency, a communication apparatus and a communication method capable of a frequency hopping communication scheme that guarantees that frequencies at the same time do not overlap are provided.

The communication device of the present invention is a communication device including a radio unit that performs frequency hopping communication and a modem unit, and the radio unit includes an antenna, a shared unit, a directional coupling unit, a filter unit, an amplifying unit, a combining unit, and a distributing unit. The modulation / demodulation unit includes an OFDM modulation / demodulation unit, an orthogonal modulation unit, an orthogonal demodulation unit, a local transmission unit, and a reference clock generation unit, and a reference clock supplied to the OFDM modulation / demodulation unit and the local transmission unit is generated as a reference clock. It supplies only from a part.
The communication method of the present invention is a communication method in a communication device including a radio unit for frequency hopping communication and a modulation / demodulation unit, and the radio unit combines an antenna, a shared unit, a directional coupling unit, a filter unit, and an amplification unit. The modulation / demodulation unit has an OFDM modulation / demodulation unit, an orthogonal modulation unit, an orthogonal demodulation unit, a local transmission unit, and a reference clock generation unit, and is supplied to the OFDM modulation / demodulation unit and the local transmission unit. Is supplied from a reference clock generator.

The communication apparatus of the present invention is the communication apparatus described above, wherein modulation of the OFDM modulation / demodulation unit increases or decreases a band or a sampling frequency.

Also, the communication device of the present invention is the communication device described above, wherein the modulation of the OFDM modulation / demodulation unit is characterized in that subcarriers are arranged on both sides centering on the carrier frequency or no carrier wave is located in the band.

Further, the communication device of the present invention is the above-described communication device in which the carrier wave is located at the center of the band (actually does not exist but remains due to hardware deterioration), the carrier wave of the quadrature modulation unit is hopped. The baseband signal (IFFT baseband signal) input to the quadrature modulation unit is used when the carrier wave is not located in the band, and subcarriers corresponding to a predetermined bandwidth are used.

Furthermore, the communication device of the present invention is the communication device described above, and the carrier wave located within the band is made to have a different frequency in time, and the carrier wave not located within the band is the input signal after IFFT. Frequency hopping is performed by controlling the presence or absence.

According to the present invention, even if two transmission frequency waves including a subcarrier are close to each other, the bandwidth and the power per subcarrier are adapted, the mutual interference is reduced, and the frequency is used for anti-interception and anti-jamming. In the frequency hopping method in which communication is performed with different frequencies, mutual interference is eliminated, so that it is possible to ensure that frequencies at the same time do not overlap.

It is a figure which shows the structural example of the system which is one Example of this invention. It is a block diagram of the radio | wireless part which is one Example of this invention. It is a block diagram of the 1st modulation / demodulation part which is one Example of this invention. It is a block diagram of the 2nd modulation / demodulation part which is one Example of this invention. It is a figure for demonstrating the 1st band change method of the communication apparatus which is one Example of this invention. It is a figure for demonstrating the 2nd zone | band change method of the communication apparatus which is one Example of this invention. It is a figure for demonstrating the signal form of the communication apparatus which is one Example of this invention. It is a figure for demonstrating the 1st frequency hopping of the communication apparatus which is one Example of this invention. It is a figure for demonstrating the 2nd frequency hopping of the communication apparatus which is one Example of this invention. It is a figure for demonstrating the method to create directly the allocation of the channel frequency with respect to the symbol time in the case of performing frequency hopping of the communication apparatus which is one Example of this invention. It is a figure for demonstrating allocation of the channel frequency at the time of the channel increase with respect to the symbol time in the case of performing frequency hopping of the communication apparatus which is one Example of this invention. It is a figure for demonstrating the method of creating directly the allocation of the channel frequency at the time of the channel increase with respect to the symbol time in the case of performing frequency hopping of the communication apparatus which is one Example of this invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a diagram showing a configuration example of a system according to an embodiment of the present invention.
In FIG. 1, transmission /

reception stations

101, 102, and 103 are communication devices.
The transmission /

reception stations

101, 102, and 103 include at least a radio unit 200 and a modem unit 300 or a modem unit 400.
The transmission / reception station 101 communicates with the transmission / reception station 102 using the frequency F1, and communicates with the transmission / reception station 103 using the frequency F3.
The transmitting / receiving station 102 communicates with the transmitting / receiving station 103 using the frequency F2.
The frequencies F1, F2, and F3 are different frequencies.
That is, the transmission /

reception stations

101, 102, and 103 can simultaneously communicate using two wave frequencies.

FIG. 2 is a block diagram of a radio unit according to an embodiment of the present invention.
In FIG. 2, the radio unit 200 includes an amplifying unit 201, a filter unit 202, a directional coupling unit 203, a shared unit 204, an antenna 205, a combining unit 206, and a distributing unit 207.
Note that the combining unit 206 and the distributing unit 207 are not included in a normal communication device, but are characteristic functional blocks in an embodiment of the present invention. Therefore, the wireless unit 200 is a normal half-duplex communication device.
The directional coupling unit 203 switches the transmission signal and the reception signal in necessary directions. The shared unit 204 shares the transmission and reception operations of the antenna 205 and the transmission and reception of each frequency.
The synthesizer 206 synthesizes high-frequency signals, and there are several types of input signals 211-1, 211-2,... On the other hand, the distribution unit 207 distributes the received and amplified signal 217 of the amplification unit 201 to receive outputs 218-1, 218-2,.

FIG. 3 is a block diagram of a first modulation / demodulation unit according to an embodiment of the present invention.
In FIG. 3, the modem unit 300 includes an OFDM modem unit 301, an orthogonal modulation unit 302, an orthogonal demodulation unit 303, a local transmission unit 304, and a reference clock generation unit 305.
The reference clock generation unit 305 generates a reference clock for performing signal processing of the entire modulation / demodulation unit 300. For example, all the clock signals, radio frequencies (transmission carrier frequency, reception carrier frequency), hopping frequency, and the like necessary for digital processing are all generated from the reference clock.

Next, the operation of the modem unit 300 will be described with reference to FIG.
The OFDM (Orthogonal Frequency Division Multiplexing) modulation of the OFDM modulation / demodulation unit 301 converts the digital signal 315 into a predetermined modulation method.
First, the OFDM modulation / demodulation unit 301 arranges necessary subcarriers at frequency intervals that are orthogonal to each other. For example, two-phase PSK (Phase Shift Keying), four-phase PSK, and multi-level QAM are respectively provided. (Quadrature Amplitude Modulation, quadrature amplitude modulation) etc. This processing is performed in the baseband region, and a signal for modulating to the next-stage radio frequency is generated. In this example, the modulation input 311 of the quadrature modulation unit 302 is obtained. The quadrature modulation unit 302 requires a SIN waveform and a COS waveform as modulation inputs, and generates them by processing such as IFFT based on the digital data 315.

The quadrature modulation unit 302 performs modulation with the high-frequency signal 316 generated by the local transmission unit 304, which is a radio signal, the SIN waveform and the COS waveform, and adds the two signals to obtain a predetermined modulation method. The radio frequency 211 is output.

Next, the reception operation of the modem unit 300 will be described.
The orthogonal demodulator 303 receives an OFDM signal that is a received signal 218 from a communication partner, demodulates it using the local signal 316 output from the local transmitter 304, and outputs a SIN waveform and a COS waveform signal 314.
The OFDM modulation / demodulation unit 301 obtains digital data 315 by performing FFT on the signal 314.

The reference clock generation unit 305 is a clock necessary for the processing of the OFDM modulation / demodulation unit 301 and a reference clock necessary for the generation of the local transmission unit 314. The reference clock generation unit 305 serves as a reference for generating all predetermined frequencies and is used in common. Therefore, the reference clock generation unit 305 generates a standard signal with compensated accuracy even if the necessary frequencies are different and the frequencies are different.
The reference clock generation unit 305 outputs, for example, a radio frequency (carrier frequency), a signal processing clock, a sampling frequency, a symbol synchronization clock, and the like.

Next, the operation of the modem unit 400 will be described with reference to FIG.
FIG. 4 is a block diagram of a second modem according to an embodiment of the present invention.
4, the modem unit 400 includes an OFDM modem unit 401, an orthogonal modulation unit 402, an orthogonal demodulation unit 403,

local transmission units

404 and 405, a reference clock generation unit 406, and a frequency setting unit 407.
The reference clock generation unit 406 generates a signal serving as a reference for performing processing of the modem unit 400 as a whole. For example, an integer multiple of the sampling frequency, FFT clock, IFFT clock, radio frequency (transmission carrier frequency, reception carrier frequency), hopping frequency, etc. are all generated from this reference clock.

The main difference between the modulation / demodulation unit 400 and the modulation / demodulation unit 300 is that the local transmission unit has two systems of the local transmission unit 404 and the local transmission unit 405, the frequency setting unit 407 is controlled by the signal 419, and the local transmission unit for transmission and reception The frequencies of 404 and 405 are set by

signals

420 and 421. If there is a delay in the radio wave between the transmitting station and the receiving station, the receiving station must synchronize with the change from the transmitting station based on the received wave. Obtain and control the required delay time difference.

Next, a band changing method according to an embodiment of the present invention will be described.
FIG. 5 is a diagram for explaining a first band changing method of the communication apparatus according to the embodiment of the present invention.
FIG. 5 shows a case where the bandwidth of one subcarrier is the same and the number of the subcarriers is changed. 5A is twice as many as the number in FIG. 5B, and the bandwidth is twice that in FIG. 5B.
In FIG. 5B, subcarriers are not generated in the right region by putting “0” in the real part and imaginary part of the complex number as the input of the subcarrier during OFDM modulation.
In FIG. 5A, the bandwidth is doubled as an example, but may be multiple times.

FIG. 6 is a diagram for explaining a second band changing method of the communication apparatus according to the embodiment of the present invention.
FIG. 6 shows an example in which one bandwidth is doubled, and FIG. 6A generates an OFDM signal with a subcarrier having a half bandwidth compared to FIG. 6B. This generation method is implemented by changing the sampling pulse which is the operating frequency of IFFT and the number of points of IFFT.
The subcarrier interval is changed by a combination of a clock obtained by dividing the sampling frequency at the time of IFFT (1 / N, N is an integer) and the number of FFT conversion points.

FIG. 7 is a diagram for explaining the signal form of the communication apparatus according to the embodiment of the present invention.
FIG. 7A shows a first mode.
That is, the subcarrier is arranged as a lower sideband and an upper sideband around the carrier (center dotted arrow).
On the other hand, FIG. 7B shows a second form.
Increase the number of IFFT conversion points and sampling frequency to generate more subcarriers and use only where necessary. (The IFFT input is set to zero for both the real part and the imaginary part except where necessary.) However, at the time of demodulation, a dotted line arrow is used as a carrier wave, quadrature demodulation is performed, and the output is subjected to FFT and taken out as a received signal only when necessary.
In addition, increase / decrease of the subcarrier is designated as IF = input, complex signal input A + jB, A = ± 1 (a value including a decimal point in the case of multilevel modulation), and unused subcarrier A = B = 0. To do.
In this method, the local transmission unit, the quadrature modulation unit, and the quadrature demodulation unit are used in common in FIGS. 7A and 7B, and the unused subcarrier is only set to A = B = 0. Simplification is possible.

FIG. 8 is a diagram for explaining the first frequency hopping of the communication apparatus according to the embodiment of the present invention.
In FIG. 8, the vertical axis represents time, the horizontal axis represents frequency, and the center of each represents the position of the carrier frequency.
The signal waveform is generated in the state of the lower sideband and the upper sideband centering on the carrier wave (indicated by the dotted arrow in the center. As in the past, it does not exist theoretically, but due to hard degradation, it actually shows an attenuation state) Then, the transmission frequency is generated as a local transmission frequency using an orthogonal modulation unit, and the transmission frequency is changed (hopped) with time.

FIG. 9 is a diagram for explaining the second frequency hopping of the communication apparatus according to the embodiment of the present invention.
The communication apparatus performs IFFT over a wide range and realizes frequency hopping by controlling the complex input of IFFT. In FIG. 9, only the portions of time 1, time 2, time 3,... Enclosed by a square are input, and the others are performed by setting the complex input to “0”.
It is also possible to hop by changing the number of subcarriers depending on the time.
Usually, the in-band hopping method is enabled.

Normally, in frequency hopping communication systems, the filter corresponding to each channel is switched and used, but especially on the transmission side (compared to reception), it is an operation at a place where the power is large, and it is a heavy burden on the filter and its switching. Will be called.
For example, the types of filters need to be different in frequency and steeply attenuated.
The switching time of the switching unit affects the hopping speed.
Insertion of the switching unit causes insertion loss and heat loss.
The type of transmission amplifying unit requires heat dissipation measures due to power loss, which affects the size and weight.
Therefore, since the signal itself has a steep attenuation characteristic outside the band, the requirement for the filter characteristic needs to use a wide band and a wide band power amplifying unit (a common amplifying unit can be used).
For that purpose, when using a wideband filter and a wideband amplifier, it is essential that the frequency is different at the same time (same symbol).

Next, a channel assignment method when frequency hopping is performed as a communication method according to an embodiment of the present invention will be described with reference to FIGS.
FIG. 10 is a diagram for explaining channel frequency allocation to symbol time when frequency hopping is performed by a communication apparatus according to an embodiment of the present invention.
FIG. 10 shows an example of using CH1 (channel 1) to CH4.
Basically, OCC (One Coincidence Code) is used. However, since the type of OCC is limited, FIG. 11 shows a method for increasing the number.

FIG. 10 shows the case of 4 channels. Since control is performed so that different frequencies are within one symbol and the frequency is OFDM between each frequency, the attenuation outside the band is large, and it can be easily realized with a wider band of the filter and a wide band of the power amplification unit.
If signals overlap at the same time and frequency, so-called interference occurs, so it is essential to control so that they do not overlap at any time, and IM (Inter Modulation), which is important as a transmitter, is also reduced. Easy.
In FIG. 10, for example, CH1 is F1, CH2 is F2, CH3 is F3, CH4 is F4 at time t1 (within t1 symbol), and CH1 is F2, CH2 is F4, CH3 is F1, and CH4 is F3 at time t2. At time t3, CH1 is F3, CH2 is F1, CH3 is F4, and CH4 is F2, and at time t4, CH1 is F4, CH2 is F3, CH3 is F2, and CH4 is F1, and all combinations do not overlap.

FIG. 11 is a diagram for explaining channel frequency assignment when the channel is increased with respect to the symbol time when frequency hopping is performed by the communication apparatus according to the embodiment of the present invention.
FIG. 11 shows a method of using a frequency of 4 channels in the channel increasing method and doubling the frequency.
In FIG. 11, at t5, t6, t7, and t8 of CH1, F is created by adding 4 to the F numbers of t1, t2, t3, and t4.
That is, at t5, 4 is added to “F1” of t1 to obtain F5. At t6, 4 is added to “F2” of t2 to obtain F6. In the same manner, F7 at t7 and F8 at t8.
Further, t1 to t8 are created with CH2, CH3, and CH4.
The areas CH5 to CH8 and t1 to t4 are created by copying the areas CH1 to CH4 and t5 to t8 created above as they are.
Next, the CH5 to CH8 and t5 to t8 regions are created by copying the CH1 to CH4 and t1 to t4 regions as they are.
FIG. 11 shows a method of increasing the hopping pattern from FIG. The hopping pattern can be increased in the same manner as described above in the same manner as described above by × 2.

FIG. 12 is a diagram for explaining a method of directly creating an allocation of channel frequency at the time of channel increase with respect to a symbol time when frequency hopping is performed by a communication apparatus according to an embodiment of the present invention.
FIG. 12 shows a case where the number of channels is increased to six. When OCC is used, the frequency F is directly assigned so that channel numbers do not overlap each symbol time.

The communication apparatus according to the embodiment of the present invention reduces mutual interference due to orthogonality of subcarriers corresponding to the bandwidth even if two waves of transmission frequencies including subcarriers are close to each other. This is a frequency hopping method in which the frequency is changed for communication, and it is guaranteed that the frequencies at the same time do not overlap.

As mentioned above, although one embodiment of the present invention was described in detail, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

・ It can be applied to the use of simultaneous transmission and reception of multiple signals by frequency hopping communication using multiple frequencies. This application claims the benefit of priority based on Japanese Patent Application No. 2015-229614 filed on November 25, 2015, the entire disclosure of which is incorporated herein by reference.

101, 102, 103, 131, 132: transmitting / receiving station, 200: wireless unit, 201: amplification unit, 202, filter unit, 203: directional coupling unit, 204: shared unit, 205: antenna, 206: combining unit, 207 : Distribution unit, 300, 400: modulation / demodulation unit, 301, 401: OFDM modulation / demodulation unit, 302, 402: orthogonal modulation unit, 303, 403: orthogonal demodulation unit, 304, 404, 405: local transmission unit, 305, 406: reference Clock generation unit 407: Frequency setting unit.

Claims

In a communication device including a radio unit and a modem unit for performing frequency hopping communication,
The radio unit includes an antenna, a shared unit, a directional coupling unit, a filter unit, an amplification unit, a synthesis unit, and a distribution unit,
The modulation / demodulation unit includes an OFDM modulation / demodulation unit, an orthogonal modulation unit, an orthogonal demodulation unit, a local transmission unit, and a reference clock generation unit,
The communication apparatus according to claim 1, wherein the reference clock supplied to the OFDM modulation / demodulation unit and the local transmission unit is supplied only from the reference clock generation unit.
The communication device according to claim 1,
The OFDM modulation / demodulation unit modulates a band or increases or decreases a sampling frequency.
The communication device according to claim 1 or 2,
The modulation of the OFDM modulation / demodulation unit is a communication apparatus characterized in that subcarriers are arranged on both sides centering on a carrier frequency or no carrier is located in a band.
The communication device according to claim 1, wherein
In the case where the carrier wave is located in the center of the band, the orthogonal modulation unit hops the carrier wave,
When the carrier wave is not located in the band, the quadrature modulation unit performs IFFT over a wide range, and uses the sub-carrier elimination corresponding to a predetermined bandwidth (the value is not used when the carrier wave is not used). A communication device.
The communication device according to claim 4, wherein
In the case where the carrier wave is located within the band, the amplification unit makes the frequency hopping frequency different in time,
In the case where the carrier wave is not located within the band, the amplifying unit performs frequency hopping by the presence or absence of an IFFT input signal (absence is set to “0”).
In a communication method in a communication device including a wireless unit that performs frequency hopping communication and a modem unit,
The radio unit includes an antenna, a shared unit, a directional coupling unit, a filter unit, an amplification unit, a synthesis unit, and a distribution unit,
The modulation / demodulation unit includes an OFDM modulation / demodulation unit, an orthogonal modulation unit, an orthogonal demodulation unit, a local transmission unit, and a reference clock generation unit,
The reference clock supplied to the OFDM modulation / demodulation unit and the local transmission unit is supplied from the reference clock generation unit,
A modulation method of the OFDM modulation / demodulation unit is to increase / decrease a band or increase / decrease a sampling frequency.
The communication method of the communication device according to claim 6,
In the case where the carrier wave is located in the center of the band, the orthogonal modulation unit hops the carrier wave,
When the carrier wave is not located in the band, the quadrature modulation unit performs IFFT over a wide range, and uses the sub-carrier elimination corresponding to a predetermined bandwidth (the value is not used when the carrier wave is not used). A communication method characterized by the above.
The communication method of the communication device according to claim 7,
In the case where the carrier wave is located within the band, the amplification unit makes the frequency hopping frequency different in time,
In the case where the carrier wave is not located in the band, the amplifying unit performs frequency hopping according to the presence or absence of an IFFT input signal (absence is set to “0”).