JP2002374569A - Communication unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a communication unit that can quickly select a frequency channel even in short range communication and start the communication. SOLUTION: The communication unit is provided with a means that discriminates a frequency channel of a received signal on the basis of a frequency strength spectral distribution of the received signal, a means that outputs a signal of the selected frequency channel when receiving the reception signal, a means that demodulates the output signal and outputs the result as received data, a means that discriminates whether or not the received data are prescribed data, and a means that processes the received data on the basis of the result of discrimination.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication technique using a plurality of frequency channels, and more particularly to a short-range communication such as a road-vehicle communication.

[0002]

2. Description of the Related Art For example, Japanese Patent Laid-Open Publication No. Hei 9-187055 discloses that a base station and a terminal communicate at any time by using a predetermined pilot channel, and when data communication is performed, an instruction is given by the pilot channel. A cellular radio system in which communication is performed between a base station and a terminal using a designated frequency channel is described.

[0003]

In a road-to-vehicle communication system (a communication system between a road and a vehicle) or the like using a short-range communication, the communication range is limited to a specific area so that the same frequency is used in a plurality of communication areas. Can be used, but communication is possible only in individual communication areas. Therefore, it is necessary to establish a new communication and reconnect each time the vehicle enters a new communication area due to a movement of a vehicle or the like. Further, even if communication between the base station and the terminal is performed at any time using a pilot channel, in the case of road-to-vehicle communication, etc., communication is difficult at any time because the communication area is discrete due to the movement of the vehicle. An object of the present invention, in view of the above-described conventional technology, is to enable a rapid selection of a frequency channel and start of communication even in a narrow-area communication system or the like in which communication cannot be performed at any time. An object of the present invention is to provide a technique capable of solving such a problem.

[0004]

In order to solve the above-mentioned problems, the present invention provides: (1) a communication device for selecting a specific one from a plurality of frequency channels and performing communication; Frequency spectrum conversion means for obtaining the frequency intensity spectrum distribution of the received signal (applicable embodiment: reference numeral 110); channel determination means for determining the frequency channel of the received signal from the frequency intensity spectrum distribution (applicable embodiment: reference numeral 120); A frequency channel selecting means (corresponding embodiment: reference numeral 130) for selecting the determined frequency channel and outputting a signal of the selected frequency channel when a received signal is input, and demodulating the selected output signal. Demodulation means for outputting as reception data (corresponding embodiment: reference numeral 140) and reception data determination means for judging whether or not the reception data is predetermined data ( Applicable embodiment: reference numeral 150) and a reception data processing means (applicable embodiment: reference numeral 160) for processing the received data based on the determination result. (2) As a communication device for selecting a specific one from a plurality of frequency channels and performing communication, a signal having a frequency bandwidth occupied by the plurality of frequency channels is reduced to a frequency bandwidth narrower than the frequency bandwidth and lower than the frequency bandwidth. Frequency conversion means (corresponding embodiment: reference numeral 170) for converting the signal into an output signal, and frequency spectrum conversion means for obtaining the frequency intensity spectrum distribution of the output signal of the frequency conversion means (corresponding embodiment: reference numeral 110)
Receiving frequency channel determining means for determining a frequency channel of a received signal from the frequency intensity spectrum distribution (corresponding embodiment: reference numeral 120); and selecting the determined frequency channel and, when a received signal is inputted, Frequency channel selecting means (corresponding embodiment: reference numeral 130) for outputting a signal of the selected frequency channel. (3) In the above (2), the frequency converting means includes a local signal generating means (corresponding embodiment: reference numeral 172) for generating a frequency within a frequency band occupied by the plurality of frequency channels; Mixer means (corresponding embodiment: reference numeral 171) for frequency-converting the received signal using the signal generated by the means. (4) As a communication device for selecting and communicating a specific one from a plurality of frequency channels, a frequency channel selecting means for inputting a received signal and outputting a signal of a designated frequency channel (corresponding embodiment: reference numeral 130) And setting a reception frequency channel to the frequency channel selection means, waiting for a specific period of time, successively switching frequency channels to be received, repeating reception standby, determining receivable frequency channels, and setting for each frequency channel Channel setting means for waiting for reception at a specified individual period or at a specific frequency set for each frequency channel (corresponding embodiment: reference numeral 180)
And a configuration including: (5) As a communication device for selecting and communicating a specific one from a plurality of frequency channels, receiving means for receiving an amplitude-modulated or angle-modulated signal, and maximum power detecting means for detecting the maximum power of the received signal (Applicable embodiment: reference numeral 31)
0), average power detection means for detecting the average power of the received signal (corresponding embodiment: reference numeral 320), and comparison means for comparing the detection output of the maximum power detection means with the detection output of the average power detection means ( (Applicable embodiment: code 330) and means for selecting a demodulation method of the received signal based on the comparison result (applicable embodiment: code 340). In the above (1), the frequency spectrum converting means (corresponding embodiment: reference numeral 110) converts the input signal into a frequency intensity spectrum distribution of a frequency band including a plurality of frequency channels and outputs intensity information for each frequency. . The channel determination unit (corresponding embodiment: reference numeral 120) determines the frequency channel of the input received signal with reference to the intensity information for each frequency converted by the frequency spectrum conversion unit. The frequency channel selection means (corresponding embodiment: reference numeral 130) passes the signal of the frequency channel determined by the frequency channel determination means and removes the signal of another frequency channel. In the above (2), the frequency conversion means (corresponding embodiment: reference numeral 170) converts the reception signal so that the frequency interval of the reception frequency channel becomes narrower and the frequency band including the plurality of input frequency channels becomes narrower. Perform frequency conversion. The frequency spectrum converting means (corresponding embodiment: reference numeral 110) converts the received signal whose frequency band has been narrowed by the frequency converting means into a frequency intensity spectrum distribution and outputs intensity information for each frequency.
Receiving frequency channel determining means (applicable embodiment: reference numeral 12)
0) refers to the intensity information for each frequency converted by the frequency spectrum conversion means to determine the frequency channel of the input received signal. The frequency channel selection means (corresponding embodiment: reference numeral 130) passes the signal of the frequency channel determined by the frequency channel determination means and removes the signal of another frequency channel. In the above (4), the frequency channel selecting means (corresponding embodiment: reference numeral 130) passes the signal of the set frequency channel and removes the signal of another frequency channel.

[0005]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a first example of the communication device of the present invention.
It is a figure which shows the Example of. In FIG. 1, 100 is a receiving antenna, 110 is Fourier transform means, 120 is a frequency channel determining means, 130 is a frequency channel selecting means,
140 is a demodulation unit, 150 is a received data determination unit, 16
0 is a reception data processing means, 200 is a transmission antenna, 21
0 is a transmission channel setting unit, 220 is a transmission data modulation unit, and 230 is a transmission data generation unit. As the receiving antenna 100, an antenna of a type suitable for a frequency band to be used, such as a horn type or a patch type, is used. The receiving antenna 100 receives a radio signal transmitted from another communication device, converts the signal into an electric signal, and outputs the electric signal. The Fourier transform unit 110 includes an A / D converter, a signal processing circuit, software, and the like, and performs a Fourier transform on the input received signal. The frequency channel determination means 120 is composed of a signal processing circuit, software, and the like.
The level of each frequency channel subjected to Fourier transform is compared, and the frequency channel having the highest level is determined as a reception channel.
Is set to pass only the determined reception channel. The frequency channel selection means 130 is composed of a local oscillation circuit controlled by a PLL tuning circuit, a frequency conversion circuit using the local signal, and a band-pass filter circuit, converts the frequency of the received signal, and is set by the frequency channel determination means. A signal of a specific frequency channel is output, and a signal of another frequency channel is removed. The demodulation means 140 is composed of a demodulation circuit prepared according to the modulation method, and demodulates the input modulation signal and outputs demodulated data. The received data determination means 150 is constituted by an error detection circuit, a synchronization detection circuit, software, or the like. When the demodulated data input by the error detection or the synchronization detection is determined to be valid reception data, the received data is determined as the received data. Output to processing means 160. Received data processing means 16
Numeral 0 is constituted by a signal processing circuit, software, and the like, and performs processing based on input received data. The transmission channel setting unit 210 is configured by a signal processing circuit, software, and the like, and sets the transmission data modulation unit 220 to a predetermined transmission channel when the received data is valid. The transmission data modulating unit 220 includes a local signal generation circuit, a frequency conversion circuit and a modulation circuit using the local signal, modulates transmission data input from the transmission data generation unit 230 with a set transmission channel, and outputs the modulated data. . Transmission data generation means 230
Is configured by a signal processing circuit, software, and the like, and generates and outputs transmission data necessary for communication in accordance with a predetermined format. As described above, the Fourier transform unit 110 performs the Fourier transform of the received signal in the frequency band including the plurality of input frequency channels.
The frequency channel determination unit 120 determines the frequency channel of the input received signal with reference to the level information for each frequency converted by the Fourier transform unit 110 at one time. The frequency channel selection unit 130 allows the signal of the frequency channel determined by the frequency channel determination unit 120 to pass, and removes the signal of another frequency channel. The demodulation unit 140 demodulates the signal of the frequency channel output from the frequency channel selection unit 130 and outputs received data. The reception data determination unit 150 determines whether the reception data output from the demodulation unit is desired data. The reception data processing unit 160 performs a reception process when it is determined that the reception data is desired data. The transmission channel setting means 210 sets the transmission channel to a predetermined transmission channel when it is determined that the received data is desired data. The transmission data generator 230 generates transmission data. The transmission data modulation means 220 receives the transmission data generated by the transmission data generation means 230 as input, modulates the transmission data using the set channel by the transmission channel setting means 210, and outputs a transmission signal.
Therefore, the received signals of a plurality of frequency channels are Fourier-transformed at a time, the level of each frequency channel is compared, the frequency channel is determined, and the validity of the demodulated data is further determined by the received data determining means. To set the transmission channel. According to the configuration of the first embodiment, it is possible to quickly and accurately select a reception frequency channel and a transmission channel.

FIGS. 2, 3 and 4 are views showing a second embodiment of the present invention. FIG.
4 is an explanatory diagram of the frequency conversion means in FIG. In FIG. 2, 170 is frequency conversion means, 171 is mixer means, and 172 is local signal generation means. The other components having the same functions as those of the first embodiment shown in FIG. The frequency conversion unit 170 includes a mixer unit 171 and a local signal generation unit 172. The frequency between the frequency channels is generated by the local signal generation means 172 and frequency-converted by the mixer means 171 so that the frequency is converted at a time to a bandwidth narrower than the bandwidth of the input reception signal.

The frequency conversion operation of the frequency conversion means 170 in FIG. 2 will be described with reference to FIGS. FIG.
FIG. 4 is a diagram schematically illustrating a frequency channel input to the frequency conversion unit 170 and the frequency and level of the local signal of the local signal generation unit 172. FIG. FIG. 4 is a diagram schematically illustrating the frequency and level of an output frequency channel. For example, each frequency channel of the input received signal is Ch1, Ch2, Ch3, Ch4, Ch5, Ch6.
And the frequency interval and level of each channel are as shown in FIG. It is assumed that the local signal generation unit 172 generates a frequency signal indicated by Local in FIG. 3 as a frequency between the frequency channels Ch1 to Ch6. When this signal is converted into a local signal by the mixer means 171 as shown in FIG. 4, Ch4, Ch3, Ch5, Ch2, Ch6, Ch1
The frequency conversion can be performed such that the frequency intervals are narrowed as shown in FIG. By this frequency conversion, the frequency bandwidth of the entire frequency channel can be narrowed by one frequency conversion. Thereafter, similarly to the embodiment shown in FIG.
Select the receiving frequency channel. According to the second embodiment, it is possible to narrow down the bandwidth of a received signal input using the frequency conversion means 170 and output the signal. Therefore,
When an A / D converter is used in the Fourier transform means 110, a low-speed, low-cost A / D converter with a narrow bandwidth can be used. Further, since the A / D conversion is performed at a low speed, the signal processing circuit can also process a low-speed signal, so that the operating frequency can be reduced, which is suitable for low power consumption and low price. Further, the frequency conversion means 170 is composed of a local signal generation means 172 for generating a signal using the frequency between the frequency channels as a local signal and a mixer means 171 for performing frequency conversion using this signal as a local signal, so that one time Channel conversion can be performed such that the frequency channel interval is reduced by only frequency conversion. For this reason, it is possible to narrow the bandwidth of the input received signal with a simple configuration.

FIGS. 5, 6, 7 and 8 show a third embodiment of the present invention. FIG. 5 is a diagram showing an example of the configuration of an apparatus, and FIG. FIG. 7 is a diagram illustrating an example of an operation flow, FIG. 7 is a diagram schematically illustrating frequency channels and levels of respective channels, and FIG. 8 is a diagram illustrating a temporal flow of channel setting. In FIG. 5, reference numeral 180 denotes a reception channel setting unit, 190 denotes a reception level detection unit, and 151 denotes a reception data determination unit. 1 and 2 have the same reference numerals. The receiving channel setting means 180 is composed of a signal processing circuit, software, and the like. The reception channel setting means 180 sets the plurality of frequency channels according to the importance level in the group A (a1, a2, a3).
And group B (b1, b2, b3), and all channels of group A and at least one channel of group B or all channels of group A are selected, so that all channels of group A in one cycle Can be set. The frequency channel selection means 130 includes a local oscillation circuit controlled by a PLL tuning circuit, a frequency conversion circuit using the local signal,
And a band-pass filter circuit, which converts the frequency of the received signal, outputs a signal of a specific frequency channel set by the reception channel setting means 180, and removes a signal of another frequency channel. Receiving level detecting means 190
Comprises a reception level detection circuit, a signal processing circuit, software, and the like. The reception level detecting means 190
Detects the level of the signal of the frequency channel output from the frequency channel selection unit 130, determines whether or not the level is higher than a set level. If the level is higher than the set level, the received data determination unit 151 In an active state so that the received data can be determined. The demodulation means 140 is composed of a demodulation circuit prepared according to the modulation method, and demodulates the input modulation signal and outputs demodulated data. The reception data determination unit 151 is configured by an error detection circuit, a synchronization detection circuit, and the like, and outputs the reception data when it determines that the input demodulated data is valid reception data. The reception data processing means 160 is configured by a signal processing circuit, software, or the like, and performs processing based on the input reception data. Receiving channel setting means 180
Is composed of a signal processing circuit, software, etc., and divides a plurality of frequency channels into groups A (a1, a2,
a3) and B group (b1, b2, b3). It is assumed that the frequency of the signal of the frequency channel of the group A needs to be selected faster than that of the group B, and the setting of the reception channel is shown in FIG.
It shall be performed as follows. That is, the frequency channel candidates are (a1, a2, a3, b1), (a1, a2, a
3, b2), (a1, a2, a3, b3), (a1, a
2, a3) and scan frequency channels.

FIG. 6 shows an operation flow of the reception data processing means 160. As a procedure, first, (1) candidate frequency channels are candidate 1 (a1, a2, a3, b1), candidate 2
(A1, a2, a3, b2), candidate 3 (a1, a2, a
3, b3) and candidate 4 (a1, a2, a3) (step 400). (2) Frequency channel candidate 1
(A1, a2, a3, b1) (step 41)
0). Next, (3) a reception channel is selected from the frequency channel candidates, and the channel is set in the frequency channel selection means 130 (step 420). (4) At this time, the reception level detected by the reception level detecting means 190 is stored (Step 430). (5) Repeat steps 420 and 430 for all frequency channel candidates. (6) The channel having the highest reception level among the frequency channel candidates is set in the frequency channel selection means 130 (step 440). (7) If the received data determination unit 151 determines that valid data has not been received, the data reception is stopped, and the process returns to 410 (step 450). (8) Received data determination means 151
If it is determined that the received data is valid, the receiving channel is determined and the selection operation is terminated (step 4).
60). When returning to the above-mentioned step 410 in the above-mentioned step 450, the frequency channel candidate is set to the candidate 2 (a1, a2, a
3, set to b2). Thereafter, candidate 3, candidate 4, candidate 1
Then, the setting is performed by sequentially switching the candidates, and the selection operation is continued. In the third embodiment, as described above, a plurality of frequency channels A group (a1, a2, a3) and B group (b
In the communication system using (1, b2, b3), the receiving channel setting means 180 selects all the channels of the group A and at least one channel of the group B, or all the channels of the group A. All channels of the group A can be set periodically. The frequency channel selection unit 130 allows the signal of the frequency channel set by the reception channel setting unit 180 to pass, and removes the signal of another frequency channel. The demodulation unit 140 demodulates the signal of the frequency channel output from the frequency channel selection unit 130 and outputs received data. The reception data determination unit 151 determines whether the reception data output from the demodulation unit 140 is desired data. The reception data processing unit 160 performs a reception process when it is determined that the reception data is desired data. The transmission channel setting means 210 sets the transmission channel to a predetermined transmission channel when it is determined that the received data is desired data. Transmission data generator 230
Generates transmission data. Transmission data modulating means 220
Receives the transmission data generated by the transmission data generation unit 230, modulates the transmission data using the set channel by the transmission channel setting unit 210, and outputs a transmission signal. According to the third embodiment, the reception channel setting unit 180 waits for reception at the frequency set for each frequency channel. It can be performed quickly according to the communication specifications. In the third embodiment, the case where the scanning frequency is changed for each frequency channel is described. However, the scanning period may be changed.

FIG. 9 shows a fourth embodiment of the present invention. The fourth embodiment is an example of a configuration in which the modulation scheme used on the receiving side can be quickly determined in correspondence with a plurality of modulation schemes. 9, 300 is a receiving antenna,
310 is a maximum power detecting means, 320 is an average power detecting means, 330 is a comparing means, 340 is a demodulating means, 350 is a received data processing means, and 360 is a front end. The input reception signal is an amplitude modulation signal or an angle modulation signal. The receiving antenna 300 uses an antenna of a type suitable for a frequency band to be used, such as a horn type or a patch type, and receives a radio signal transmitted from another communication device, converts the signal into an electric signal, and outputs the electric signal. Front end 36
0 converts the frequency of the signal received by the receiving antenna 300 to an intermediate frequency and removes unnecessary signals of other frequencies.
The maximum power detection means 310 is configured by a maximum power detection circuit, detects the maximum power of the input intermediate frequency signal,
Outputs the power value. The average power detection means 320 includes an average power detection circuit, detects the average power of the input intermediate frequency signal, and outputs a power value. Comparison means 330
Is composed of a comparison circuit, compares the input maximum power value and the average power value, and determines that the input signal is an angle modulation signal if the maximum power value and the average power value are substantially the same,
If the maximum power value is larger than the average power value, it is determined that the signal is an amplitude modulation signal. The demodulation means 340 comprises an amplitude modulation signal demodulation circuit for demodulating the amplitude modulation signal and an angle modulation signal demodulation circuit for demodulating the angle modulation signal.
When the input signal 30 is determined to be an amplitude-modulated signal, demodulation is performed using an amplitude-modulated signal demodulation circuit, and when the input signal is determined to be an angle-modulated signal, an angle-modulated signal demodulation circuit is used. Perform demodulation. Received data processing means 35
Numeral 0 is composed of a signal processing circuit and software, and performs processing of the demodulated signal output from the demodulation means 340. As described above, the maximum power detection means 310 detects the maximum power of the input signal. The average power detection means 320 detects the average power of the input signal. The maximum power of the amplitude modulation signal is larger than the average power because the envelope of the amplitude fluctuates. On the other hand, since the amplitude modulation signal has a small change in the envelope of the amplitude, the maximum power and the average power are almost the same. Therefore, by comparing the maximum power and the average power of the input signal by the comparing means 330, it is possible to determine whether the signal is an amplitude modulation signal or an angle modulation signal. Based on the comparison result, the demodulation means 340 selects a demodulation method for an amplitude modulation signal or a demodulation method for an angle modulation signal, and outputs a demodulation signal. According to the fourth embodiment, when determining whether the modulation method of a received signal is amplitude modulation or angle modulation, the modulation method of an input signal can be quickly determined without demodulation.

[0011]

According to the present invention, in narrow-area communication such as road-to-vehicle communication, it is possible to quickly select a frequency channel, set a transmission channel, and start communication. Further, it is possible to quickly determine the modulation method of the received signal and start communication.

[Brief description of the drawings]

FIG. 1 is a diagram showing a first embodiment of the present invention.

FIG. 2 is a diagram showing a second embodiment of the present invention.

FIG. 3 is a frequency channel diagram input to a frequency conversion unit in FIG. 2;

FIG. 4 is a frequency channel diagram output from a frequency conversion unit in FIG. 2;

FIG. 5 is a diagram showing a third embodiment of the present invention.

FIG. 6 is a diagram illustrating an example of an operation flow of a reception channel setting unit.

FIG. 7 is a diagram schematically illustrating frequency channels and levels of respective channels.

FIG. 8 is a diagram showing a temporal flow of channel setting.

FIG. 9 is a diagram showing a fourth embodiment of the present invention.

[Explanation of symbols]

100, 300: receiving antenna, 110: Fourier transform means, 120: frequency channel determining means, 130
... frequency channel selection means, 140, 340 ... demodulation means, 150, 151 ... reception data determination means, 16
0, 350: reception data processing means, 170: frequency conversion means, 171: mixer means, 172: local signal generation means, 180: reception channel setting means, 19
0: reception level detection means, 200: transmission antenna,
210: transmission channel setting means, 220: transmission data modulation means, 230: transmission data generation means, 300: reception antenna, 310: maximum power detection means, 320 ...
Average power detection means, 330: comparison means, 360: front end.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Tetsuo Nakano 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Inside Digital Media Development Division, Hitachi, Ltd. F-term in the Automotive Equipment Group of Hitachi, Ltd. (reference) 5H180 AA01 BB04 5J103 AA11 AA13 BA06 CB07 DA03 FA05 GA06 GB01 HC02 HD05 5K067 BB03 DD44 EE61 GG01 GG11 JJ11 JJ31

Claims (5)

[Claims] 1. A communication apparatus for selecting a specific one of a plurality of frequency channels and performing communication, comprising: a frequency spectrum converting means for obtaining a frequency intensity spectrum distribution of an input received signal; Channel determining means for determining a frequency channel of a signal; frequency channel selecting means for selecting the determined frequency channel and outputting a signal of the selected frequency channel when a received signal is input; and the selected output Demodulation means for demodulating a signal and outputting the data as reception data; reception data determination means for determining whether the reception data is predetermined data; and reception data processing means for processing the reception data based on the determination result. A communication device, comprising: 2. A communication apparatus for performing communication by selecting a specific one from a plurality of frequency channels, wherein a signal having a frequency bandwidth occupied by the plurality of frequency channels is converted into a signal having a frequency narrower than the frequency bandwidth and having a lower frequency. Frequency converting means for converting to a bandwidth and outputting the frequency signal; frequency spectrum converting means for obtaining a frequency intensity spectrum distribution of an output signal of the frequency converting means; and a receiving frequency channel for determining a frequency channel of a received signal from the frequency intensity spectral distribution. A communication apparatus comprising: a determination unit; and a frequency channel selection unit that selects the determined frequency channel and outputs a signal of the selected frequency channel when a received signal is input. 3. The frequency conversion means includes: a local signal generation means for generating a frequency within a frequency band occupied by the plurality of frequency channels; and a reception signal using the signal generated by the local signal generation means. 3. The communication apparatus according to claim 2, comprising: mixer means for performing frequency conversion. 4. A communication device for selecting a specific one of a plurality of frequency channels and performing communication, comprising: a frequency channel selecting means for receiving a received signal and outputting a signal of a specified frequency channel; Set the receiving frequency channel for the selection means and wait for a specific period of reception, repeat the reception standby by sequentially switching the receiving frequency channel, determine the receivable frequency channel, and set the individual period or A communication device comprising: a reception channel setting unit that waits for reception at an individual frequency set for each frequency channel. 5. A communication device for selecting and communicating a specific one of a plurality of frequency channels, a receiving means for receiving an amplitude-modulated or angle-modulated signal, and a maximum power for detecting a maximum power of the received signal. Detecting means; average power detecting means for detecting the average power of the received signal; comparing means for comparing the detected output of the maximum power detecting means with the detected output of the average power detecting means; and a receiving signal based on the comparison result. Means for selecting the demodulation method of the above.