JPH0568897B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention provides a system for performing confidential communication in a wireless communication system having at least one control channel and a plurality of communication channels between a master station communication device and a wireless terminal device. This relates to a confidential communication method for

[Technical background of the invention and its problems]

Cordless telephones have conventionally been known as this type of wireless communication system.

However, in conventional systems, control signals such as paging signals and call channel designation signals used in control channels, and call signals used in call channels have confidential patterns that are unique between the master station communication device and the wireless terminal equipment. Fixed to type. For this reason, the wireless terminal devices with which a master station communication device can perform confidential communication are limited to those with the same confidential pattern, and a single master station communication device can receive confidential communication from multiple wireless terminal devices. The drawback was that it could not be done.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned drawbacks and provide a confidential communication system that allows a plurality of wireless terminal devices to perform confidential communication with one master station communication device.

[Summary of the Invention] The present invention performs connection control such as confirmation of a paging signal and designation of a call channel prior to a call using a secret pattern common to a plurality of wireless terminal devices. The above purpose is achieved by switching to a unique confidential conversation pattern for communication.

[Embodiments of the invention]

FIG. 1 is a block diagram showing an embodiment of a cordless telephone device to which the present invention is applied. In the same figure, 1, 2, 3,...n are subscriber line terminals, 1A, 2
A, 3A, nA are connection devices as master station communication devices,
1B, 2B, 3B, and nB are cordless telephones as wireless terminal devices, and 1C, 2C, 3C, and nC are wireless sections in which the cordless telephones 1B to nB are normally used.

In such a configuration, the connection devices 1A to nA
The connection control signal transmitted and received on the control channel between the cordless telephones 1B and 1B to nB consists of a first frame and a second frame, as shown in FIG. A service bit IB is provided. Further, the first frame is provided with a control signal type signal CS, and the second frame is provided with a device identification number ID _o indicating the unique device number of each of the cordless telephones 1B to nB.

Here, connecting device 1A and cordless telephone 1B
The following describes the operation during a phone call with .

First, on the cordless telephone 1B, a button for calling the connecting device 1A is operated. Then,
A calling signal is transmitted from the cordless telephone 1B with a signal configuration as shown in FIG. In this case, the calling signal is transmitted to the cordless telephones 1B to 1n using a common secret pattern.

In response to the ringing signal from the cordless telephone 1B, the connecting device 1A returns to the cordless telephone 1B a call channel designation signal that designates an empty call channel among the plurality of call channels. Then, a secret pattern switching signal is transmitted from the cordless telephone 1B. When the connecting device 1A receives the confidential pattern switching signal, it returns a confidential pattern switching response signal to the cordless telephone 1B, and also sends the device identification number of the cordless telephone 1B.
The secret pattern is switched according to ID _o . on the other hand,
Cordless telephone 1B, which has received the secret pattern switching response signal, switches the secret pattern for calling to the secret pattern corresponding to its own device identification number ID _o , and after this connection operation is completed, activates the call circuit and starts the call operation. Transition.

Call operation like this (transmission and reception of call signals)
In the connection control before moving to , a secret pattern common to each cordless telephone is used, and immediately before the call operation starts, the communication pattern is switched to a secret pattern unique to each cordless telephone. For this reason, the wireless section
nC's cordless telephone nB and other wireless sections 1C~
Confidential communication is also possible with the 3C connection devices 1A to 3A. Furthermore, even if cordless telephones 1B and nB switch places during a call through the same communication channel in wireless sections 1C and nC, or even if they enter the same wireless area, telephones 1B and nB will differ from each other. Since a confidential conversation pattern is used, the contents of the call will not be leaked to the other party.

FIG. 3 is a block diagram of a control means for performing such confidential communication, which includes a microprocessor 10 for controlling connection control operations and communication operations according to predetermined communication procedures, and a read-only memory (ROM) 11 that stores programs and secret pattern data, and a control section 12 that modulates the transmitted signal SD according to the secret pattern specified by the microcomputer unit 10 and demodulates the received signal RD. Transmission section 13, oscillation section 14
and a receiving section 15.

Among these, the control unit 12 is a signal processing circuit 1 that switches confidential communication patterns and communication channels.
20, a scrambling circuit 121 that modulates the transmitted signal SD according to a designated secret pattern, and a descrambling circuit 1 that demodulates the received data RD.
22. The transmission signal SD modulated by the scrambling circuit 121 is sent to the transmission section 13.
Sent from. In this case, the carrier frequency of the transmission signal SD is switched by applying the channel switching signal CH to the oscillator 14. On the other hand, the received signal RD received by the receiving section 15 is demodulated by the descrambler circuit 122, and sent to the microcomputer unit 1 via the signal processing circuit 120.
Transferred to 0.

Note that 16 is an oscillator that generates an operating clock signal CK.

The scramble circuit 121 and the descramble circuit 122 are composed of a shift register SR and an AND gate, as shown in the detailed circuit in FIG.
AG ₁ ~AGn and exclusive OR circuit EOR ₁ ~
The scramble circuit 12 is configured by EORn.
1, the transmission signal SD is shifted by the shift register SR in synchronization with the clock signal CK, and the logical product of the shifted transmission signal and the secret pattern data SCD is calculated by the AND gates AG ₁ to AGn, and then the AND gate AG ₁ By calculating the exclusive OR of the output signals of ~AGn in circuits EOR ₁ ~EORn, the transmission signal SD is modulated according to the secret pattern data SCD. On the other hand, the descrambling circuit 122 is configured to demodulate the received signal RD in accordance with the secret pattern data SCD by an operation opposite to that of the scrambling circuit 121.

With such a configuration, the transmission signal SD is modulated according to the secret pattern data SCD and transmitted. In addition, the received data RD is confidential pattern data
Demodulated according to SCD.

Therefore, by reading the secret pattern data SCD corresponding to each of the cordless telephones 1B to nB from the memory 11 based on the device identification number IDn and providing it to the scramble circuit 121 and the descramble circuit 122 immediately before transitioning to the telephone conversation operation, To perform confidential communication without leaking the contents of a call to other cordless telephones.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, a plurality of wireless terminal devices can perform independent confidential communication with one master station communication device. Therefore, if applied to a local area network that connects a data terminal and a host computer using a wireless line, it is possible to protect data confidentiality and prevent access from other data terminals. Furthermore, when applied to a home telephone system, it is possible to perform confidential communication with each of a plurality of terminal telephones using only one master station communication device.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention;
Fig. 2 is a diagram showing the structure of the control signal, Fig. 3 is a block diagram showing an embodiment of the control means for performing confidential communication, and Fig. 4 is a circuit showing the detailed structure of the scramble circuit and descramble circuit. It is a diagram. 1A~nA...Connection device, 1B~nB...Cordless telephone, 1C~nC...Wireless section, ID _o ...Device identification number, 121...Scramble circuit, 12
2... Descramble circuit.

Claims (1)

[Scope of Claims] 1. A device comprising: a plurality of master station communication devices; and a plurality of wireless terminal devices; one of the plurality of wireless terminal devices is one of the plurality of master station communication devices; A connection signal is transmitted and received with one master station communication device using a control channel, and one of the plurality of communication channels is selected from the control channel based on the connection signal.
and transmits a call signal between one of the plurality of wireless terminal devices and one of the plurality of master station communication devices using the communication channel. In a wireless communication system that performs transmission and reception, the transmission and reception of the connection signal is performed using a signal modulated by a confidential communication pattern common to the plurality of wireless terminal devices, and after switching to the communication channel, the common confidential communication pattern is used for each of the plurality of wireless terminal devices. A confidential communication system characterized in that the communication signal is transmitted and received by switching to a confidential communication pattern unique to each wireless terminal device, and using a signal modulated by the switched confidential communication pattern unique to each wireless terminal device. 2 The secret pattern unique to each wireless terminal device is
2. The confidential communication system according to claim 1, wherein the confidential communication system is set in correspondence with a device identification number of each wireless terminal device.