JPH10107695A - Frequency hopping system spread spectrum communication device and its interference wave avoiding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stop defect that is weak at broadband interference in a frequency hopping system by receiving entire bands before communication, storing a band which has interference waves over a fixed level and performing frequency hopping by using only use bands except the stored band. SOLUTION: When the power of a transmitter-receiver is turned on, a controlling part 11 drives a receiving synthesizer 116 to be able to receive entire bands to be used. A carrier detector 113 detects whether radio carrier that has more than a fixed level exists in a fixed time among received frequencies. In this way, interference wade memory 111 stores all the frequencies that have interference waves within use band. A hopping frequency to avoid interference waves is created except the bands stored in the memory 111. Then, satisfactory communication can be performed by using only hopping frequencies to avoid interference waves.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spread spectrum communication apparatus using a frequency hopping method and a method for avoiding an interference wave.

[0002]

2. Description of the Related Art Spread spectrum communication includes a direct spread system, a frequency hopping system, and a hybrid system combining both. The direct spreading system is resistant to wideband interference and simple in hardware, but has a so-called near-far problem and requires complicated functions such as transmission power control. The frequency hopping method is resistant to narrowband interference and has no perspective problem, but has the drawback that hardware for high-speed hopping is difficult and that broadband interference is relatively weak. The hybrid system can make use of both advantages, but has complicated hardware.

Recently, however, a high-speed frequency synthesizer has been developed and attention has been paid to the fact that there is no perspective problem, so that a frequency hopping system has been considerably adopted.

[0004]

An object of the present invention is to eliminate the disadvantage of the frequency hopping system that is susceptible to wideband interference.

[0005]

SUMMARY OF THE INVENTION A feature of the present invention is that before communication, the entire band to be used is received, a band having an interference wave of a certain level or higher is stored, and only the used band excluding the stored band is stored. Is used to perform frequency hopping.

[0006]

Embodiments of the present invention will be described below in detail. FIG. 1 shows an example of a configuration of a frequency hopping spread spectrum transceiver equipped with an interference wave avoiding method according to the present invention.
2 is an encoder, 103 is a modulator, 104 is a transmission mixer, 105 is a transmission band-pass filter, 106 is received data, 107 is a decoder, and 108 is a decoder.
Is a demodulator, 109 is a reception mixer, 110 is a reception bandpass filter, 111 is an interference wave memory,
Reference numeral 112 denotes a control unit, reference numeral 113 denotes a carrier detector, reference numeral 114 denotes a synchronization extractor, reference numeral 115 denotes a transmission frequency synthesizer, reference numeral 116 denotes a reception frequency synthesizer, reference numeral 117 denotes an antenna coupler, and reference numeral 118 denotes an antenna. FIG. 2 is a control flow of interference wave detection. FIG.
FIG. 4 is an explanatory diagram of a method 1 for creating a hopping frequency for avoiding interference waves, and FIG. 4 is an explanatory diagram of a method 2 for creating a hopping frequency for avoiding interference waves. The operation will be described below with reference to these drawings.

In FIG. 1, it is necessary to transmit the transmission data 101, and when a transceiver (not shown) is turned on,
The control unit 112 drives the reception synthesizer 116 so that the entire band to be used can be received. That is, as shown in the flow of FIG. 2, first, the lowest frequency f1 of the used band is received (STEP 201, STEP 202), and the carrier detector 113 detects whether or not the received frequency f1 has a radio carrier of a certain level or more for a certain time. (Step 203). If detected (YES in STEP 203), the interference wave memory 11
For example, "1" is written at the frequency f of 1 as having an interference wave (STEP 204). If not detected (STEP
203, NO), for example, “0” is written at the frequency f of the interference wave memory 111 as no interference wave (STEP 20).
5). Next, the control unit 112 controls the reception synthesizer 116.
Is driven to receive a slightly higher frequency (f + Δf) (STEP 206), and the same control as above is performed. When this control is repeated up to the highest frequency f2 of the used band (STE
P207), all the frequencies having the interference wave in the use band are recorded in the interference wave memory 111.

In this control, it is usually convenient to use the interval of the hopping frequency as Δf used.
If a long detection time is required to detect an interference wave in the entire use band, it is conceivable to use an interval larger than the hopping frequency interval and detect the interference wave in a wide band at a time. Further, since this communication is spread spectrum communication, a certain level of carrier exists in the used band. Therefore, the detection level of the interference wave must be set to a level equal to or higher than an average level detected at that frequency. Further, when another communication is being performed in a location very close to the main communication, it is possible that the detected frequency is used by another communication and that a very large carrier exists. However, since the spread spectrum communication is a frequency hopping spread spectrum communication, the time used in the communication for the frequency is the time of the frequency hopping interval, which is extremely short. Therefore, this problem can be avoided by setting the detection time longer than the hopping interval.

Next, a method (method 1) for creating a hopping frequency for avoiding an interference wave excluding the band recorded in the interference wave memory 111 will be described. First, when a hopping frequency pattern to be used is determined in advance between two parties performing communication, the band stored in the interference wave memory 111 is transferred to the communication partner prior to communication.
Assuming that the band of the interference wave frequency is f (a) to f (b),
Transfer the values of f (a) and f (b). As a transfer method, it is appropriate to use a control channel normally provided for spread spectrum communication. Between the two communicating parties,
If the hopping frequency pattern to be used is not determined in advance, the hopping frequency pattern to be used is also transferred to the communication partner.

In FIG. 3, it is assumed that pattern 1 is a hopping frequency pattern to be used. Here, f1 to f10 are used as hopping frequencies. Now f1
<F2 <... <f9 <f10, f6 <f (a) <f7, f8 <
Assuming that f (b) <f9, the transmitting side determines from the pattern 1 in FIG. 3 that the f7 and f8 of the hopping frequencies to be used are interfering frequencies. A new hopping frequency pattern is created by skipping f8, and frequency hopping is performed using this pattern. That is, in FIG.
Is encoded by the encoder 102, undergoes primary modulation by the modulator 103, and is frequency-hopped by the transmission mixer 104 by the transmission frequency synthesizer 115. The control unit 112 drives the transmission frequency synthesizer 115 so that the hopping frequency becomes the selected pattern.
The frequency-hopped transmission signal passes through the transmission bandpass filter 105 and the antenna coupler 117 and passes through the antenna 11
8 is sent out. On the other hand, the receiving side also creates pattern 2 in FIG. 3 from the hopping frequency pattern of pattern 1 known in advance and the transferred values of f (a) and f (b),
Used for reception. That is, on the receiving side, the antenna 118,
The reception signal that has passed through the antenna coupler 117 and the reception bandpass filter 110 is mixed with the output of the reception frequency synthesizer 116 by the reception mixer 109, and demodulated from the frequency-hopped signal to a signal of a fixed carrier. At this time, the control unit 112 drives the reception frequency synthesizer 116 and generates an output having a certain frequency difference from the frequency of the pattern 2 in synchronization with the output of the synchronization extractor 114. The output of the receiving mixer 109 is the demodulator 10
8 and received by the decoder 107.
It becomes 6.

As described above, according to the present invention, good communication can be performed by using only the hopping frequency in which the interference wave is avoided. Of course, the number of hopping frequencies used will be less than the originally planned number, and the noise due to a slight increase in the correlation with the hopping frequency used in other communications will increase, but there will be interference. Higher quality communication can be performed than when a hopping frequency is used.

Next, another method (method 2) for creating a hopping frequency for avoiding an interference wave except for the band recorded in the interference wave memory 111 will be described. It is assumed that there are ten usable hopping frequencies from f1 to f10. First, a pattern having no mutual correlation using, for example, seven waves among them is set in advance. An example is shown in FIG. In FIG. 4, patterns 1 to 5 are set. Now, the frequency band of the interference wave is f (a) to f (b), and f
Assuming that 6 <f (a) <f7 and f8 <f (b) <f9, among the hopping frequencies to be used, f7 and f8 are interfering frequencies, so that five predetermined hopping frequency patterns are used. From among the patterns that do not use f7 and f8. In FIG. 4, it can be seen that pattern 5 is a pattern that does not use f7 and f8 to be obtained. Next, the communication partner is notified of pattern 5, and communication using pattern 5 is performed as a hopping frequency. How to communicate is method 1
Is the same as that described in the description. In this method, it is necessary to notify the other party of the pattern to be used each time communication is performed, but it is not necessary to notify the interference band. Further, since the hopping frequency patterns used are patterns having no correlation with each other, communication in which interference from other communication is minimized and interference waves are removed becomes possible. In the above explanation,
The hopping frequency pattern from which the interfering wave has been removed is extracted from the table, but it is also possible to calculate a pattern using the hopping frequency excluding f7 and f8 without communication with each communication. .

[0013]

According to the present invention, before communication, the entire band to be used is received, a band having an interference wave of a certain level or higher is stored, and frequency hopping is performed using only the used band excluding the stored band. In addition, it is possible to eliminate a disadvantage that the frequency hopping spread spectrum communication is weak against broadband interference. In addition, the present invention enables economical and easy realization of a hopping frequency pattern setting that eliminates an interference wave only with software without changing the hardware configuration of a frequency hopping spread spectrum communication transceiver. it can.

[Brief description of the drawings]

FIG. 1 is a configuration example of a transceiver for a frequency hopping spread spectrum communication provided with an interference wave avoiding method of the present invention.

FIG. 2 is a control flow of interference wave detection.

FIG. 3 is an explanatory diagram of a method 1 for creating a hopping frequency for avoiding an interference wave.

FIG. 4 is an explanatory diagram of a method 2 of creating a hopping frequency for avoiding interference waves.

[Explanation of symbols]

 111 interference wave memory 112 control unit 113 carrier detector 115, 116 frequency synthesizer

Claims (4)

[Claims] 1. In a frequency hopping spread spectrum communication system, before communication, the entire band to be used is received, a band having an interference wave of a certain level or higher is detected and stored, and the used band except the stored band is used. A method for avoiding an interference wave in a frequency hopping spread spectrum communication, wherein frequency hopping is performed using only a frequency of a band. 2. At the beginning of communication, the detected and stored frequency band is notified to a communication partner, and a hopping frequency within the stored frequency band is skipped from a predetermined frequency hopping pattern. 2. The method according to claim 1, wherein frequency hopping is performed. 3. At the beginning of communication, a frequency hopping pattern not including a hopping frequency in the detected and stored frequency band is extracted, and the frequency hopping pattern is notified to a communication partner, and the frequency is determined based on the hopping pattern. 2. The method according to claim 1, wherein hopping is performed. 4. A frequency hopping spread spectrum communication apparatus, comprising: an interfering wave detecting means for receiving an entire band to be used before communication and detecting a band having an interfering wave of a certain level or more; Storage means for storing the interference wave detected by the above, and transmission control means for performing frequency hopping using only the frequency of the use band excluding the interference wave stored in the means. Frequency hopping spread spectrum communication device.