JPS6090438A - Digital mobile radio relay system - Google Patents

Abstract

PURPOSE:To prevent the difficulty of communication between subscribers due to the increase in the level of secrecy by providing a ciphering radio communication system with a means which distributes a normal secret code for data communication to a repeater station side. CONSTITUTION:In a scrambling and descrambling type radio communication system which enciphers the contents of a subscriber group and transmits them with a radio wave; a repeater station B which relays a transmit signal from a subscriber station A is provided with normal repeater sets B1-Bn and special repeater sets B1'-Bn'. The special repeater sets B1'-Bn' have monitors and returning means of a format corresponding to a secret code for special operation, and when there is an incoming signal in the format corresponding to the secret code for special operation, a secret code in normal operation is distributed to subscriber stations with this format. Consequently, a failure in communication is prevented even when some subscriber station loses a key.

Description

[Detailed Description of the Invention] Field of the Invention The present invention relates to a wireless communication system, and in particular, the present invention is directed to a so-called wireless communication system in which the contents of communication within a group of subscribers are not known to anyone other than the subscribers. The present invention relates to scrambled and descrambled wireless communication systems.

<Prior Art and Background> Conventionally, since this type of communication uses radio waves as an intermediary, it is theoretically possible to intercept it, so communication content has been sent and received in scrambled or descrambled format to prevent it from being deciphered. In order to make deciphering more difficult, the scrambling and descrambling (hereinafter not simply abbreviated as S and D) formats are not fixed in a single format.
For example, there are quite a few types (numbers) of S such as 2 111i1 and 5.
, D format is prepared in advance and stored in each station device with a binary header code, for example, for each specific area, day, or cycle according to the operational agreement within the subscriber. Today in area A, S, D format 10
00.8 area is format], 050.

Area C is format 2000. --- Only the subscribers are notified in the form of 1, and only their fellow subscribers know about it in advance, which means that although it can be intercepted, it cannot be deciphered, further increasing the strength of 1I1. There is.

Note that this principle is the same even when there are multiple communication hands, and S and D formats are assigned to each band.
All that is required is to inform subscribers of the operational arrangements that allocate the bands that will be mainly used depending on the region.

According to these operational agreements, the subscriber's transceiver can select the S or D format used in that area on that day and set the S or D format of its own transceiver to enable subscriber communication. It is.

Note that in the case of a system in which multiple channels are used, and the transmitter/receiver selects a channel by a channel changeover switch, it may have a function to set the S and D formats for each channel.

Mobile stations set up in accordance with these operational agreements and equipped with transceivers can communicate with each other by mounting a relay station on their sleeves while moving with each other, making it possible to strongly prevent interception and decoding by third parties. However, on the other hand, sudden changes may need to be made, operational arrangements may not reach all ends, mobile stations may move far from the designated area to communicate, and in rare cases, notification may not be given. However, if you forget the key, you will not be able to exchange information between subscribers because you will not have the "key." This becomes clear if we consider the mobile radio systems of the Self-Defense Forces as an example.

<Purpose and Features> In view of the above, the purpose of the present invention is to determine in advance at least one S or D format that is not used for normal information communication,
This is S used for information exchange.

In addition to the operating arrangements for the D-type group, an arrangement that does not change for a longer period of time, such as one month or a year, and a special arrangement different from the former for a special group that is common regardless of region. It is to operate. In other words, the "key" for information exchange is encrypted using a cipher that can only be opened with a special "key."
The system is operated by distributing this information via wireless communication.

The feature of the present invention is to convert audio into a digital code in order to achieve the above-mentioned objective, and further convert the code into a scramble by selecting one of a plurality of scramble and descramble formats prepared corresponding to the secret code. a mobile station that has, as a communication set, a transmission function that transmits a signal, a reception function that descrambles and demodulates a received signal using the reverse procedure described above, a function that interrupts transmission and reception signals between the mobile stations, and a monitor and In an interruptible mobile radio system having a relay station having a function of interrupt transmission, the relay station is provided with a monitor and return means of a format corresponding to a secret code for special operation in addition to a format corresponding to a secret code for continuous operation, and The means is always kept on standby for monitoring, and when an incoming call is received in a format corresponding to the special operating secret code, the secret code which is always in use is notified in that format.

<Embodiment> FIG. 1 is an explanatory diagram of an object to which the present invention is implemented, and is a conceptual diagram of a mobile radio interruption system.

Figures 2, 3, 4 and 5 are explanatory diagrams of one embodiment of the present invention, and Figures 6 and 7 are explanatory diagrams of the hardware configuration of mobile stations, relay stations, etc. FIG. 1 is an explanatory diagram of an embodiment of the invention, and is an explanatory diagram of operational arrangements, which is a software configuration side.

In the figure, Aa, Ab-... are mobile stations, A is the mobile station's communication set, I-, Ba- is the relay station, and B is the relay station's communication set.
And B,,B,',B,! ,B2',-・-・-B
n and Bn' respectively indicate pairs of relay cents and special relay cents for n channels prepared at the relay station.

FIG. 5 is a conceptual diagram of the mode set panel for these communication sets Δ to B, with dial C for channel selection.
and dials 11-m for secret code sets, indicating selections and possible settings. Furthermore, for convenience of explanation, it is assumed that communication is carried out in a dual-frequency, single-power type.

To explain the hardware side of this configuration, the mobile station determines the communication center, selects a channel (calling hand) that can be used within the area, selects the secret code (secret code D) specified in the operational agreement for the call, and relays it. If you hang up the station, call the other station, switch to reception and wait for a response, you will receive a response, so you will know that you are communicating in normal confidential mode.

When the secret code is garbled, there is no response from the other station, and monitoring is not established at the relay station, so it is possible to determine that something is wrong.

In addition, Fig. 3 shows a block diagram of the communication center on the mobile station side. ), the received signal is selected by a band-pass filter 3, amplified by a high-frequency amplifier 4, mixed with the oscillation signal of a local oscillator 10 by a mixer IO, an intermediate frequency signal is extracted by a band-pass filter 6, and amplified by an intermediate frequency amplifier 7. Digital f! The scrambled and sent encrypted digital information obtained by demodulation by the lJd device 8 is input into the descrambler 9, which selects a mode according to the secret code, and converts it back to the original digital information. If the information is audio, the decoder 11 converts the digital signal into an analog signal, and the audio amplifier 12 amplifies it into audio information that reaches the operator's ears via the speaker 23. However, if it is facsimile information etc., it will remain digital and will be sent as facsimile etc. (not shown).
Send to.

In the case of transmission, the selector switch is set to 2 transmission mode, and when you speak into the microphone 22, the low frequency amplifier 21 amplifies it, the encoder 20 converts the analog signal into a digital signal, and the mode is selected according to the secret code. A signal that has been encrypted by a scrambler 18 and subjected to transmission band restriction via a low-pass filter 17 is input to a modulator 16, and the output signal is mixed with the oscillation signal of a local oscillator 19 by a mixer 15. A signal with a transmission carrier frequency is selected by a bandpass filter 14, amplified by a high frequency amplifier 13, and transmitted from an antenna 1 via a changeover switch 2.

Note that when transmitting a digital signal, it is manually transmitted directly before the scrambler 18. Further, the conversion contents of the scrambler 18 and the conversion contents of the descrambler 9 are prepared as a pair corresponding to one secret code in the relationship of conversion and inverse conversion.

・ Also, Figure 4 shows that 3 is applied to 13+ and Bi' on the relay station side.
A repeater loop loops common receiving side configurations 33 to 39 and transmitting side configurations 50 to 55 connected via 2, and a high frequency amplifier 34 through a bandpass filter 33 of the receiving side configuration. +lj, mixed with the oscillation signal of the local oscillator 39 by the mixer 35, selected by the bandpass filter 36, amplified by the intermediate frequency amplifier 37, and demodulated by the digital demodulator 38. Descrambler 40 corresponding to secret code D. Decoder 41. Via the audio amplifier 42 to the speaker 43, a monitor section for third-party communications and a descrambler 44 set to the content corresponding to the secret code K selected in accordance with the operation list of the special operation arrangement side are connected. via the decoder 45 and the squelch circuit 46. audio amplifier 4
A special monitor unit for key request monitoring is connected to the speaker 49 via the 7, and the squelch 46 is controlled and output from the speaker only when the detector 48 detects that there is an incoming signal in the special mode. shall be allowed to do so.

When the mode selector switch 5G is set to the relay mode, the received signal is passed through the receiving and transmitting loops and is relayed as is.

On the one hand switching switch 56, an interrupt mode can be selected from the relay station as the other mode by operating an interrupt switch 63, and the interrupt mode side has a scrambler 58 for normal communication and a scrambler for special communication. a switch 57 for switching the encoder 60 . Low frequency amplifier 61.
Consisting of micro 2, secret code D is set by switch 57.
Interrupt transmission can be performed by selecting either the scramble conversion corresponding to the secret code K or the scramble conversion corresponding to the secret code K.

When a mobile station that happens to have lost its key communicates with the relay station on a channel in a format corresponding to secret code K, the detector 4
8 and a voice output is made, and the call status and request contents can be monitored, so the relay station side can distribute the confidential code D for the call-back request in its confidential mode in response to the request. In order to further increase the level of confidentiality, the requester may be confirmed using a pre-arranged password before being distributed.

FIG. 6 shows an example of an operational agreement list for data communication.

This list is usually distributed by means other than wireless, and is revised periodically, for example, every week, but if there are special circumstances, a special edition may be used preferentially as an interrupt for a shorter specific period. A version may be published. A channel assigned to each region and a confidential code D to be used during the operation period are assigned to this, and if both subscribers have these contents, communication is established.

Also, Figure 7 shows an example of an operational arrangement for a special secret code used to request and distribute keys.
This is an example of a secret code common to each region that is changed twice.

By combining these hardware configurations with operational arrangements, it is possible to carry out highly secure confidential communication, and in special cases, the confidential key can be distributed as an encryption using a confidential wireless communication system that is different from the encryption system. It is possible to prevent injury from occurring.

Furthermore, the amount of communication on the special operation side is not large in terms of the system structure, so even if the operation period and area of use are expanded, the time that the radio waves are exposed is short, so it is clear that the strength can be maintained sufficiently to prevent decoding. be.

Effects> As explained above, according to the present invention, a secret code for normal data communication can be exchanged by simply installing a special operation arrangement and a specially operated monitor and transmission means on the suspended station side. This has the effect of making it easier to use a high-strength secret system, since it can overcome the drawback that communications cannot be established between subscribers by increasing the secret communication strength.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of an object to which the present invention is implemented, FIGS. 2, 3, 4, and 5 are explanatory diagrams of an embodiment of the present invention. Explanation of an Embodiment of the Invention Fig. 2 indicates the communication center of the mobile station, B the communication center of the relay station, C the dial for channel selection, and Ii the dials for the private code sets, respectively. Y-'Go, Ei-] 5 names No. 6 Diagram 7 D

Claims (1)

[Claims] A transmission function that converts audio into a digital code, selects one of a plurality of scramble and descramble formats prepared for the secret code, scrambles the code, and transmits the code; A mobile station having, as a communication module 1-, a reception function that descrambles and demodulates a received signal using the reverse procedure described above. In a relay mobile radio system that has a relay station that has the function of relaying transmitted and received signals between mobile stations, and the function of monitoring and interrupt transmission, the relay station side has a format that supports a secret code that is always in use, as well as a format that supports a special operation code. A monitor and return means in a format corresponding to the confidential code is provided, and this means is always on standby for monitoring.When a message is received in a format corresponding to the above-mentioned special operating confidential code, the confidential code that is in continuous operation in that format is transmitted. A digital mobile radio relay system characterized by notification.