JPH04137931A - Time division communication privacy call method for mobile body communication - Google Patents

Abstract

PURPOSE:To make interception difficult by varying a time length accommodated in an operating time slot and separated timewise depending on each frame. CONSTITUTION:An input signal from a gate exchange is inputted to a cryptographic time chip signal generating circuit group 78 and divided into a time interval according to a command of a cryptographic provision device 76. Then the output is inputted to a signal speed conversion circuit group 51, in which a prescribed speed conversion is caused. Furthermore, a signal sent from a radio base station 30 to a gate exchange is processed such that an output of a radio reception circuit 35 is inputted to a signal speed decoding circuit group 38 via a signal selection circuit 39, subject to speed conversion and inputted to a cryptographic time chip signal decoding circuit group 79. The signal is divided at a time interval according to a command of a cryptographic decoder 75 in the circuit, resulting that a telephone signal is reproduced and inputted to a signal processing section 31.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a confidential communication method in time-division communication of mobile communication. More specifically, given a radio channel, one of the many mobile radios in the service area is communicating with an opposing radio base station by setting up a radio link. Another object of the present invention is to provide a method for improving the privacy of communication by eliminating the possibility that radio equipment that does not belong to the system tunes into the same radio channel at the same time slot and intercepts communication contents.

[Prior Art] In mobile communication using voice using a small zone method, a method employing a time division time compression multiplex signal is described in the following document.

Literature 1. Ito: Mobile phone system study - Time division time compression F
Proposal of M modulation method-'' IEICE technical report RC389-11
July 1989 document 2. Ito “Study of mobile phone system - Time division time compression F
Theoretical study of M modulation system” IEICE technical report RC389-39
In October 1989, in Document 1, a transmission signal (baseband signal) is divided into predetermined time intervals and stored in a memory circuit, and when read out, the speed n is faster than the speed at which it is stored in the memory circuit. The carrier wave can be read out in a predetermined time slot at twice the high speed, angle-modulated or amplitude-modulated with the signal accommodated by this time slot, and used in mobile radios and radio base stations for time-intermittent transmission and reception. A built-in wireless receiving circuit has a receiving mixer that communicates with each other, a wireless transmitting circuit has a transmitting mixer, a synthesizer applies the signal to the receiving mixer of the wireless receiving circuit, and a transmitting mixer of the wireless transmitting circuit. A switch circuit is provided for each synthesizer, and the output of each synthesizer is applied intermittently, and this intermittent state is synchronized for both transmission and reception, and the same intermittent transmission and reception as described above is applied to the radio base station communicating with the mobile radio. In order to extract only the signals contained in the predetermined time slot, the receiving side opens and closes the radio receiving circuit to receive the signals, demodulates the signals, and stores the obtained signals in the storage circuit. However, there is an example of a system in which the baseband signal, which is the original signal that has been transmitted, can be reproduced by reading it out at a low speed that is 1/n of the speed at which it is stored in this memory circuit. It has been reported.

In addition, Reference 2 examines adjacent channel interference and co-channel interference, which are problems when applying the TCM (time division time compression multiplexing)-FM method described above to small zones. Possibilities of realizing the system have been shown by appropriately selecting parameters. However, there is a possibility that a radio device that does not belong to the system may tune to the same radio channel and time slot and intercept the communication content, and it is necessary to prevent this from the viewpoint of privacy protection. , there is nothing known regarding this type of technology.

[Problems to be Solved by the Invention] The system construction examples in Documents 1 and 2 described above describe a method for transmitting D-CM (time division time compression multiplexing) signals transmitted from a wireless base station to a large number of mobile wireless devices. In response to this, a method of transmitting a TCM signal from a mobile radio to a radio base station has been disclosed, but depending on the disclosed transmission method, it may be difficult for other radios that do not belong to the system to Tune to the radio channel and time slot and monitor the communication content! There remained an issue to be solved, which is that it is relatively easy to do so.

[Means for solving the problem j When transmitting a TCM signal, the wireless base station retrieves a code from the No. II8 storage unit, compresses the time given to the transmitted signal according to the code, and encrypts the segmented time length. A function is provided to instruct the type of encryption, F@ encoding, and decoding method to the mobile radio device that communicates with the other party.

[Effect] Since we decided to change the length of time separated by BBJ in the time slot used for each frame, it is possible to provide a high encryption function equivalent to that of a digital signal even in a CM signal. Therefore, the time
It becomes extremely difficult for a third party's wireless device not belonging to the system to overhear the system because it does not know the order in which the time lengths of the signals accommodated in the slots are assigned, making it possible to ensure the privacy of communications.

L Embodiment] FIG. 1A, FIG. 1B, and FIG. 1C show a system configuration for explaining an embodiment of the present invention.

In FIG. 7A, 10 is a general telephone network, and 20 is a gateway exchange for connecting the telephone network 10 and the wireless system. 30 is a wireless base station and a barrier switch 20
It includes an interface with the mobile radio equipment 100 (100-1 to 10O -n) and a wireless transmitting/receiving circuit for transmitting and receiving frontline signals.

Here, between the barrier switch 20 and the wireless base station 30,
Communication Channel C) There is a transmission line for transmitting communication signals 22-1 to 22-n including communication signals 11 to CHn and control signals.

FIG. 1B shows a circuit configuration of mobile radio device 100 that communicates with radio base station 30. FIG.

Received signals such as 1ljlll signals and call signals received by the antenna section enter a radio receiving circuit 135 that includes a receiving mixer 136 and a receiving section 137, and the output communication signal is sent to a speed recovery circuit 138, a control section 140, and a clock signal. Regenerator 1
41.

In addition, a part of the output of the receiving section 137 is sent to the OFj code decoder 17.
5, the code sent from the radio base station 30 is decoded, and the decrypted output of the decryptor 175 is input to the control unit 40 and the time piece signal decoding circuit 179. The clock regenerator 141 regenerates a clock from the received signal and sends it to the speed restoration circuit 138 and the control unit 1.
40 and a timing generator 142.

The speed restoration circuit 138 restores the speed (pitch in the case of an analog signal) of the segmented control signal or compressed and segmented communication signal in the received signal and sends it to the encrypted time piece signal decoding circuit 179. The encrypted time piece signal decoding circuit 179 has the same function as the encrypted time piece signal decoding circuit group 79 of the wireless base station 30, which will be described later. Then, as a continuous signal, the telephone unit 101 and the control unit 14
It is entered as 0.

In addition, the signals in the time slot, which is usually placed at the beginning of one frame, include a frame synchronization signal as well as an uncompressed control signal, and this control signal includes cryptographic information, etc. This is decoded by a decryptor 175 and input to the control section 140. Regarding cryptographic information, there is a cryptographic storage unit 177 that stores, for example, a random number table, and this and the control unit 140 exchange information with each other.

Further, when the mobile radio device 100 takes the lead in encrypting communications, the code storage unit 177 and the code adder 176 are used.

The communication signal output from the telephone unit 101 is sent to the encrypted time piece 15 forming circuit 178. This circuit has the same function as the II8 encoded time piece signal forming circuit group 78 of the wireless base station 30, which will be described later. If it is not operating, the telephone signal is time-segmented at the time interval instructed by the control unit 140 according to the code transmitted from the wireless base station 30, and then sent to the speed conversion circuit 131.

In the speed conversion circuit 131, the speed (pitch in the case of an analog signal) of the communication signal is made high (compressed) and applied to the wireless transmission circuit 132 including the transmission mixer 133 and the transmitter 134.

Incidentally, the FIB encoded time piece signal forming circuit 178 receives the code from the coder 176 operated by the control signal given from the control unit 140, and the signal transmitted to the wireless base station 30 is FP? Became number 1. Here, the cipher 176 operates only when it is desired to create a cipher different from the encryption process instructed by the wireless base station 30. When the same content as the cryptanalysis method instructed by the radio base station 30 is applied to transmission in reverse, the above-mentioned operation will occur.

Further, in the timing generator 142, the clock regenerator 1
41 and a control signal from the control unit 140, the transmission/reception intermittent controller 123. Speed conversion circuit 131. It supplies necessary timing to the encrypted time piece signal forming circuit 178, the encrypted time piece signal decoding circuit 179, and the speed restoration circuit 138.

The mobile radio device 100 further includes a synthesizer 121-1.
and 121-2, and selector switches 122-1, 122
Transmission/reception intermittent controller 12 that generates signals for switching the switch 122-2 and the changeover switch 122-1 and 122-2, respectively.
3 and a timing generator 142, a synthesizer 121-1, 121-2 and a transmit/receive intermittent controller 1.
23 and timing generator 142 are controlled by a control section 140. Each synthesizer 121-1.121
-2 is supplied with a reference frequency from the reference crystal excavator 120.

A wireless base 830 is shown in FIG. 1C.

N-channel communication signal 22-1 with barrier exchange R20
22-n are connected to a signal processing unit 31 forming an interface through a transmission line.

Now, the barrier exchange is the communication signal 22- sent from 20.
1 to 22-n are input to the signal processing unit 31 of the wireless base station 30. The signal processing section 31 is equipped with an amplifier for compensating for transmission loss, and also performs so-called 2-wire to 4-wire conversion. That is, the input signal and the output signal are mixed and separated, and the input signal from the barrier switch 20 is sent to the encrypted time piece signal forming circuit B-¥78, which includes the encrypted time piece signal forming circuits 7B-1 to 78-n. After becoming an encrypted signal, it is sent to the signal speed conversion circuit group 51.

Signal speed restoration circuit! The output signal from ¥38 is decoded by the encrypted time scale signal decoding circuit group 7 including encrypted time piece signal decoding circuits 79-1 to 79-n, and then sent to the signal@processing section 31. , and is further transmitted to the barrier switch 20 using the same transmission path as the input signal. Of the above, barrier exchange t
The input signal from the ff120 is input to the encrypted time piece signal forming circuit u78, and is divided into time intervals according to instructions from the coder 76.

Next, this output is sent to many signal speed conversion circuits 51-1 to 51-5.
The signal is input to a signal speed conversion circuit group 51 including signals 1 to 1n, and undergoes predetermined speed (pitch) conversion.

Further, the signal transmitted from the radio base station 30 to the barrier exchange t120 is inputted from the radio reception circuit 35 to the signal speed restoration circuit group 3B via the signal selection circuit 39, and is speed (pitch) converted. Encrypted time scale signal decoding circuit group 79
is input to. In this circuit, telephone signals are reproduced and input into the signal processing section 31 as a result of dividing the telephone signals into time intervals according to instructions from the decryptor 75.

Next, the operations of the encrypted time piece signal forming circuit group 7B and the signal speed converting circuit group 51 are explained in FIGS. 2A-1 and 2A-2.
This will be explained in detail using figures.

FIG. 2A-1 shows the encrypted time piece signal forming circuit 78- for communication channel number 1 among the encrypted time piece signal forming circuit group 78 and the signal speed converting circuit group 51 in FIG. 1C.
Only communication channel number 1 and signal speed conversion circuit 51-1 are selected, and similar operations are performed for communication channel numbers 2 to n, so communication channel number 1 is used as a representative. 2A-2 are schematic diagrams showing signal processing states of each part of the circuit shown in FIG. 2A-1.

Now, in Figure 2A-1, from the left side, Figure 2A2 (a)
A series of telephone signals from the signal processing section 31 enters the F@ encoded time piece signal forming circuit 78-1. The encrypted time piece signal forming circuit 78-1 is a kind of switch circuit as shown in FIG. 2A-1, and this switch is
Whether it is turned to the side or to the side 78-1-2 is controlled by the output signal of the coder 76, including the length of time. Therefore, the series of telephone signals is divided into two, and the time piece signal is either present on the 78-1-1 side or on the 78-1-1 side as shown in Figure 28-2 (b>).
Either exists on the -1-2 side, and neither exists on the side.

These signals are sent to the signal speed converter 51-1-1 or 5
1-1-2, time compression is performed, and the signals shown in FIG. 2A-2(C) are output. The outputs are mixed to form one series of time-compressed signals shown in FIG. 2A-2(d), which is input to the signal allocation circuit 52-1.

Next, the operations of the signal rate restoration circuit group 38 and the encrypted time scale signal decoding circuit group 79 to which the output of the signal selection circuit group 39 is applied will be explained in detail with reference to FIGS. 2B-1 and 2B-2. .

Figure 2B-1 shows the signal speed restoration circuit 13 in Figure 1C.
8 and the encrypted time scale signal decoding circuit group 79, only the signal speed restoration circuit 38-1 and the encrypted time scale signal decoding circuit 79-1 for the communication channel number 1 are selected. Since the same operation is performed in the channels .about.n, the communication channel number 1 will be used as a representative. FIG. 2B-2 is a schematic diagram showing the signal processing state of each part of the circuit shown in FIG. 2B-1.

Now, in Figures 2B-1 and 2B-2, the second
The output of the signal selection circuit 391, not shown in FIG. 2B-2(a), is input to the signal speed restoration circuit 38-1 from the right side of FIG. 2B-1. The signal speed restoration circuit 3B-1 includes a switch 48-1 and a memory circuit 38-1i as shown in FIG. 2B-1.
~38-1-3, switch 4 installed on the input side
8] is switched to the 4.8-1-1 side, or to the 48-1-2 or 4B-1-3 side by receiving a timing signal from the timing generation circuit 42 within the frame. This is done cyclically, in synchronization with the time slots of The number of signals divided by this switch 48-1 is related to the maximum and minimum time lengths of the encrypted time piece signals, and in the case shown, the ratio of the time lengths of the encrypted time piece signals is Since it is 2, it is divided into 3. Generally, this ratio is p〉
1, the number of divisions is C) + 1 if p is an integer,
If p includes numbers below the decimal point, they will all be rounded up and given as an integer.

The switch 48-1 shown in FIG. 2B-1(a)
As shown in Fig. B-2 (b), the time-compressed time segment signal divided into three parts is each processed by a signal speed restorer 38-.
1-1 to 3B-1-3, time expansion is applied to each signal, and the signal reaches the state before being restored as shown in FIG. 2B-2(C). However, as it is clear from Figure 2B-2 (C), the original signal cannot be restored if this is done because the implementation part of the original signal is not known and all the signals in the time slots are regarded as the longest time piece signal. This is because it contains a large amount of noise components because it is restored using

In order to restore the actual audio signal from among the above signals, a @ code decoding signal from the code decoder 75 is required, and according to this signal, the encrypted time piece signal decoders 79-1-1 to 79
In -1-3, it is necessary to cut the signal time piece into the same length as that at the time of transmission. As a result, Figure 2B-2 (
Time piece signals such as d) are faithfully reproduced, the sum of these signals is taken, and the sum is sent to three processing units as a series of telephone signals.

Now, the control of the radio reception circuit 35 or the output of the call signal is performed by a signal selection circuit 39 that selects a signal for each time slot.
-1 to 39-n is input to the signal selection circuit group 39,
Here, speech signals are separated corresponding to each speech channel c1-11 to CHn. This output undergoes signal speed (pitch) restoration in a signal speed restoration circuit group 38 including signal speed 1 base circuits 38-1 to 38-n provided for each channel, and then is sent to a signal processing section 31. After being input and subjected to 4-wire to 2-wire conversion, this output is sent as a communication signal 22- to the barrier switch 2o.
1 to 22-n.

Next, the functions of the signal speed conversion circuit group 51 will be explained.

By storing input signals such as audio signals and control signals divided into fixed time lengths in a memory circuit, and reading them out at a speed that is 15 times faster than when they were stored, the signal time can be stored. It becomes possible to compress the length. The principle of the signal speed conversion circuit group 51 is the same as when playing back audio recorded by a tape recorder at high speed.
), BBD (Buc
Brigade Device) can be used, and the memory used in television receivers and tape recorders that compress or expand the time axis of conversations can be used (Reference 'I#X: Kosaka et al.
Tape recorder that compresses/expands the time axis of conversations Nikkei Electronics July 26, 1976 92-133
Page) COD and BBD illustrated in signal speed conversion circuit group 51
As described in the above-mentioned document, the circuit using the circuit can be used as it is for the signal speed restoration circuit group 38, and in this case, the clock from the clock generator 41 and the control section 4 can be used as is.
This can be achieved by receiving a timing signal from a timing generator 42 that generates timing based on a control signal from 0, and making the reading speed slower than the writing speed.

Barrier exchange! The control or audio signals outputted from 20 via the signal processing unit 31 are input to the signal speed conversion circuit group 51, where they are subjected to speed (pitch) conversion processing and then signal allocation where signals are allocated to each time slot. Circuit group 52
is applied to This signal allocation circuit group 52 is a buffer memory circuit that stores one section of high-speed signals output from the signal speed conversion circuit group 51, and uses timing information from the timing generation circuit 42 given in accordance with an instruction from the control section 40. The signal in the buffer memory is read and transmitted to the wireless transmission circuit 32. As a result, when viewed in terms of channel correspondence, communication signals are arranged in series without overlapping in chronological order, and when all control signals or communication signals, which will be described later, are implemented, they appear as if they were continuous signal waves. become.

The state of this compressed signal is shown in FIG. 2C and will be explained.

The output signal of the signal speed conversion circuit group 51 is sent to the signal allocation circuit 15.
2 and are given time slots in a predetermined order. SDO, SDl in Figure 2C (a)
, SO2·, SDn indicate that the speed-converted communication signals are allocated to each time slot. The reason why the time width of each time slot in the figure is long and short is that the signal length on the time axis changes in the output of the encrypted time piece signal forming circuit group 78, as described above. However, because it is necessary to synchronize each time slot, the rising cycle of each time slot is the same throughout all frames, regardless of the length of the signal piece.

Note that the first time slot SDo of each frame accommodates frame synchronization and control signals;
Slots SD1 to SDn accommodate speech signals and/or control signals in response to an incoming call to mobile radio 100 or a call originating from mobile radio 11100. If a speech signal is not implemented, the speech signal portion is supplemented with an empty slot signal, or in some systems no signal is transmitted at all, including the carrier wave.

In this way, as shown in FIG. 2C, 4a), in the wireless transmission circuit 32, the time slots SDO,
A signal is applied to the modulation circuit in one frame from I to SDn. The time-series multiplexed signal to be transmitted is angularly modulated in the radio transmission circuit 32, and then sent out into space from the antenna section.

When making or receiving a telephone call, the wireless base station 30
As mentioned above, the control signal transmission between the mobile radio VS100 and the mobile radio VS100 is carried out using time slot SDO, but depending on the system, it is possible to use either within the telephone signal band or outside the telephone signal band. is also possible. Figure 3A shows these frequency relationships. In other words, Figure (a) is an example of an out-of-band signal, and as shown in the figure, there are signals on the low frequency side (250Hz) and the high frequency side (3850H7).
can be used. This signal is also used, for example, when it is desired to send a control signal during a call, or when a signal is being encrypted, which will be described later.

FIG. 3A (b) shows an example of an in-band signal, which is used when making and receiving calls.

Although the above examples were all tone signals, it is possible to transmit many types of signals at high speed by increasing the number of tone signals or by modulating the tone and making it into a subcarrier signal.

The above was a case of an analog signal, but if a digital data signal is used as a control signal, it is also possible to digitally encode the audio signal and transmit the two by time division multiplexing. The circuit configuration in this case is shown in FIG. 3C. This converts the audio signal into a digital encoding circuit 91.
This is an example of a case in which the data signal is digitized by a multiplex conversion circuit 92, multiplex-converted with a data signal by a multiplex conversion circuit 92, and applied to a modulation circuit included in the wireless transmission circuit 32. The audio signal and the control signal can be extracted separately by receiving the signal with the opposing receiver and performing the operation in the demodulation circuit in the opposite manner to that shown in FIG. 3C.

On the other hand, the signal sent from the mobile radio device 100 is received by the antenna section of the radio base station 30, and is received by the radio receiving circuit 35.
is input to. FIG. 2C (b>) schematically shows this upstream input signal.

That is, each frame F1. F2. F3. ... time slot SU1. SU2. , Sun is a mobile radio 1001.100-2. . . . indicates a transmission signal addressed to the wireless base station 30 from 100n.

Also, each time slot SU1. SU2. ..., Su
If the contents of n are shown in detail, it consists of a call signal and/or a control signal, as shown in the lower left of FIG. 2C (b). However, from the mobile radio device 100 to the radio base station 30
When you want to make a call or make an emergency communication, use the time slot SUO, which is always placed at the beginning of each frame.

Now, among the input signals that have arrived at the wireless base station 30, the control signal is immediately sent to the control unit 40 from the wireless receiving circuit 35.
added to. However, depending on the magnitude of the speed conversion rate, it is also possible to apply the output of the signal speed restoration circuit group 38 to the control unit 40 after performing similar processing on the call signal. Further, the call signal is applied to the signal selection circuit group 39.

A timing signal from a timing generation circuit 42 that generates a predetermined timing is applied to the signal selection circuit group 39 according to a control signal instruction from the control unit 40, and a synchronization signal and a control signal are generated for each time slot SU1 to SU5LIn. The signal or speech signal is separated and output. Each of these signals is
The signal is input to the signal speed restoration circuit group 38. As already described in detail, this circuit has the function of inversely converting the speed conversion circuit 131 (FIG. 1B) in the mobile radio device 100 on the transmitting side, thereby faithfully reproducing the original signal and transmitting it to the gateway exchange. It will be sent to 20.

The manner in which signals are transmitted in the signal space according to the present invention will be explained below using the required transmission band and the relationship between this and adjacent wireless channels.

As shown in FIG. 1C, the control signal from the control section 40 is applied to the wireless transmission circuit 32 in parallel with the output of the signal allocation circuit group 52. However, depending on the magnitude of the speed conversion rate, it is also possible to apply the signal to the wireless transmission circuit 32 from the output of the signal allocation circuit group 52 that has undergone the same processing as the call signal.

Next, as shown in FIG. 1B, the mobile radio device 100 also has a circuit configuration required when the radio base station 30 has one communication channel among its functions.

Original signal, for example, audio signal (0.3kH2~3.0kl-
FIG. 3B shows the frequency distribution on the output side when (7) passes through the signal speed conversion circuit group 5] (FIG. 1C). That is, if the audio signal is converted 15 times as described above, the frequency distribution number J of the signal will be expanded to <4.5 kt-1z~45k)-12 as shown in Figure 3B.

Although the frequency distribution of the signal has been expanded here, it should be noted that the waveform form has simply been stretched along the frequency axis, and the waveform itself has not changed. Also, for signal encryption, the time length of the time piece signal is different for each frame, but when compressing the time, the time length of the time piece signal is 1]
, 5, so that the maximum frequency of the signal accommodated in each time slot does not differ.

Now, FIG. 3B shows a case where the control signal is simultaneously transmitted using the lower frequency band of the audio signal. Among these signals, the control signal (0.2 to 4.0kHz)
and call signal NCH1 (4.5~45kHz TESD1)
) is a time slot, e.g. S
Suppose that it is accommodated in Dl. Other time slot S
The same applies to the audio signals accommodated in D2 to SDn.

That is, time slot sDi <r=2°3, -
, n> accommodates control signals (0.2 to 4.0 kt-1z) and communication signals cHi (4.5 to 45 kHz). However, the signals within each time slot are arranged in chronological order. Therefore, signals in more than one time slot at a time are never applied to the wireless transmitter circuit 32 at the same time.

These call signals are sent to the wireless transmission circuit 32 along with control signals.
When added to the angle modulator included in the angular modulator, the required transmission band requires at least fo±45 kHz. However, fC is the radio carrier frequency. If there are a plurality of wireless channels given to the system, the high speed ratio of the signal by the signal speed conversion circuit group 51 is limited to a certain value due to the limitations on these frequency intervals. The frequency interval of multiple wireless channels is f
,. , and the maximum signal speed due to the above-mentioned speed increase of the audio signal is fH, then the following inequality must hold between the two.

f > 2 f H ep On the other hand, in digital signals, audio is usually digitized at a speed of about 64 kb/s, so read by raising the scale on the horizontal axis in Figure 3B, which explains the case of analog signals, by about one digit. Although necessary, the relationship in the above equation also holds true in this case.

In addition, the control signal that enters the radio base station 30 from the mobile radio device 100 is input to the radio reception circuit 35, but a part of its output is input to the control unit 40, which in turn inputs the signal selection circuit group 39. The signal is sent to the signal speed restoration circuit group 38 via the signal speed restoration circuit group 38. After the control signal on the rear right undergoes a speed conversion (conversion to a low speed signal) that is completely opposite to that at the time of transmission, it becomes the same signal speed as that used in the general telephone network 10 and is transmitted via the signal processing section 31. and is sent to the barrier exchange 20.

Next, the call originating/receiving operation of the system according to the present invention will be explained by taking the case of a voice signal as an example.

(1) Call origination from mobile radio device 100 This will be explained using the flowcharts shown in FIGS. 4A and 4B.

When the power of the pre-move II device 100 is turned on, the wireless reception circuit 135 in FIG.
0→mobile radio 100) radio channel (channel Cl-
11). If the system is provided with more than one radio channel, i) the radio channel exhibiting a received input field of magnitude R; ii) the radio channel dictated by the control signal contained in the radio channel; and iii) within the radio channel. A radio channel (hereinafter referred to as channel CH1), such as a channel with an empty time slot among the time slots, enters the receiving state according to the procedure determined by the respective system. This applies to each frame F1. shown in FIG. 2C(a). F2. ..., time slot SD within
This is possible by capturing the synchronization signal within i. The control unit 140 sends a control signal to the synthesizer 121-1 to generate a local frequency that enables reception of the wireless channel CH1, and the switch 122-1 is also fixed to the synthesizer 121-1 side. It is in.

Therefore, when the receiver of the telephone unit 101 is off-hook (starts making a call) (3201, FIG. 4A), the synthesizer 121-2 of FIG. 1B generates a local frequency that enables transmission of the wireless channel CH1. A control signal is received from the control section 140 to cause the control to occur.

Further, the switch 122-2 is also turned to the synthesizer 1212 side and becomes fixed. Next, the calling control signal output from the telephone unit 101 is sent out using the radio channel CH1. This control signal has a frequency band shown in FIG.
It is sent using O.

The transmission of this control signal is limited to time slot SUO, and is sent in bursts, and no signal is transmitted during other time periods, so it does not adversely affect other communications. However, if the speed of the control signal is relatively slow or the amount of information in the signal is large and cannot be accommodated in one time slot, the same time slot of the next frame or Sent using slots.

Specifically, the following method is used to capture the time slot SUO. The control signal transmitted from the radio base station 30 includes a synchronization signal and a subsequent control signal, as shown in FIG. becomes possible.

Furthermore, this control signal includes control information such as currently used time slots and unused time slots (empty time slot display). Depending on the system, time slot sD; <r=1.2°...,
n) may only contain synchronization and speech signals when they are being used by other communications; By receiving this control signal, the mobile radio device 100 can know which time thrower 1 to should be used to send out the calling signal.

Note that if all the time throwers l~ are in use, it is not possible to make a call on this radio channel, and it is necessary to sweep and search for another radio channel.

In other systems, there may be no empty slot indication in any of the time slots, in which case the following audio multiplex signals SD1, SD2 . ..., 5
It is necessary to search for the presence of Drl one after another and check for empty time slots.

Now, returning to the main topic, the mobile radio device OO, which has received the control information sent from the radio base station 30 by one of the above methods, determines in which time slot it should send out the call control signal. The determination can be made including the transmission timing.

Furthermore, when encrypting a communication signal in a system led by the wireless base station 30, the mobile wireless device 100 has received the encryption information at this point, and once communication starts, the control unit 100
40 can enter a standby state for a code to be provided to the coded time piece signal forming circuit 178. However, confidential conversations will not be made until the call has started.

Assuming that time slot SUO for uplink signals is an empty slot, it is decided to use this empty time slot, and a control signal for calling is sent out, and the necessary timing is extracted from the response signal from the wireless base station 30. burst-like control signals can be sent out.

If a call is made from a mobile radio at the same time, the calling signal will not be transmitted properly to the radio base station 30 due to call collision, and the operation will have to be restarted from the beginning, but this probability is When viewed as a system, this value is kept to a sufficiently small value. If call collisions are to be further reduced, the following method may be used. If the mobile radio 100 finds an empty time slot in which it can make a call, it does not use the entire time slot, but uses only the first half for some mobile radios, and only the second half for other mobile radios. This is the way to do it.

In other words, the part used by time thrower 1 as a calling signal is divided into several types, and this is used to classify a large number of mobile radios into groups, and each group is assigned one time slot. The method is to give the time zone within. Another method is to create many different frequencies for control signals, group a large number of mobile wireless devices, and give them to each city. According to this method, iti! with different frequencies! Even if the I control signals are transmitted simultaneously using the same time thrower 1, no interference will occur in the radio base station 30. The above two methods may be used separately, or if used in combination, the effects will increase synergistically.

Now, suppose that the call control signal from the mobile radio device 100 is successfully received by the radio base station 30 and the identification number N) of the mobile radio device 100 is detected (S202).
The control unit 40 of the mobile radio device 100 detects the ID (identification signal) of the mobile radio device 100 (52O2) and confirms the ID.
The communication channel designation signal and encryption information necessary for making a call to the mobile radio device 100 are sent to the downlink time slot SD.
Send to mobile radio device 100 using O (3203)
.

The mobile radio device 100 that has received the control information sent from the radio base station 30 searches the code storage unit 177 from the code information, frame number, and communication channel to find the time slot number assigned to itself. Switch to the specified time slot SU1 (S204>,
Using this, the slot switching completion signal is sent to the wireless base station 30.
(3205>) and wait for a dial tone to be sent (3206>).

The radio base station 30 naturally expects this and is waiting for reception, and upon receiving the slot switching completion report (3207>
, sends a calling signal together with the ID of the mobile radio device 100 to the gateway exchange 20 (3208). On the other hand, the gateway switch 20 turns on the necessary switches among the switch groups included in the barrier switch 20, and sends dial-1 to -- to the wireless base station 30 (3210, FIG. 4B).

This dial tone is transferred by the radio base station 30 using time throwers 1 to SD1 (S211>, and the mobile radio 100 confirms that the communication path has been set (3212). Transition to this state When mobile radio 1
Since a dial tone is heard from the handset of the telephone FiS101, the dial tone begins to be sent. This dial signal is speed-converted by the speed conversion circuit 131 and sent out from the wireless transmission circuit 132 including the transmission section 134 and the transmission mixer 133 using the uplink time slot SUI (S213>. Thus, the transmitted dial signal is The radio receiving circuit 35 of the base station 30 receives the signal.The radio base station 30 already responds to the calling signal from the mobile radio 100, gives the time slot to be used, and receives the signal from the radio base station 30. The selection circuit group 39 and the signal allocation circuit group 52 are operated to receive the upstream time slot SU1 and to receive the downstream time slot SD1.
It is now in a state where it is transmitting a signal. Therefore, the dial signal sent from the mobile radio m"+oo is
After passing through the signal selection circuit 39-1 of the signal selection circuit group 39, it is input to the encrypted time piece signal decoding circuit group 79 via the signal speed restoration circuit group 38, where the original transmission signal is restored and subjected to signal processing. It is transferred to the gateway exchange 20 as a call signal 22-1 via the section 31 (3214,), and a call path to the telephone network O is set (3215>).

On the other hand, the input signal from the gateway exchange 20 (initially a $ control signal, a call signal when a call is started) is polarized in the encrypted time column forming circuit group 78 via the signal processing unit 31 in the wireless base station 30. , the polarized signal undergoes speed conversion in the signal speed conversion circuit group 51, and is then given a time slot SD1 by the signal allocation circuit 52-1 of the signal allocation circuit group 52. Then, it is transmitted from the radio transmission circuit 32 to the mobile radio 11100 using the time slot SD1 of the downlink radio channel. The mobile radio device 100 is waiting for reception in the time slot SD1 of the radio channel CH1, and the radio reception circuit 135
and its output is input to the speed recovery circuit 138. In this circuit, the original signal of the transmission is restored and input to the handset of the telephone section 101. Thus, a call is started between the mobile radio device 100 and a regular telephone within the regular telephone network 10 (3216>).

Further, as mentioned above, the secret conversation is also prepared for both the radio base station 30 and the mobile radio device 100, and is immediately executed when the conversation starts.

To do this, the control unit 40 sends the coder 7 at the same time as the start of the call.
6 to start the operation.

Note that confidential communication is also possible in communication for control between the radio base 830 and the mobile radio 100, such as the above-mentioned communication channel assignment, which is performed before the start of a call.
I omitted the explanation because it is not very practical.

The call is terminated by turning on the receiver of the telephone unit 101 of the mobile radio device 100 (3217>), and the end of the call signal and the on-hook signal from the control unit 140 are transmitted to the speed conversion circuit 1.
31 from the wireless transmission circuit 132 to the wireless base station 30 (3218>), and the control unit 140 stops the operation of the transmission/reception intermittent controller 123 and switches the switches 122-1 and 122-2 to the synthesizer. It is fixed to the output ends of 121-1 and 121-2.

On the other hand, in the control unit 40 of the radio base station 30, the mobile radio device 1
When the call termination signal is received from 00, the call termination signal is transferred to the gateway exchange v120 (3219), and the switch group (not shown) is turned off to end the call (S220).
. At the same time, the signal selection circuit group 39 and signal allocation circuit group 52 in the radio base station 30 are opened.

In the above description, control signals are exchanged between the radio base station 30 and the mobile radio v1100 by the signal rate conversion circuit group 51.
Although it has been explained that the signal speed restoration circuit group 38, etc. is not passed through, this is for the convenience of explanation, and like the audio signal, the signal speed conversion circuit group 51, the signal speed restoration circuit group 38, the control signal speed conversion circuit 4B, etc. Communication can be performed through the signal processing unit 31 without any problem.

(2) Incoming call to mobile radio device 100 The mobile radio device 100 is on standby with the power turned on. In this case, as explained in the section regarding the call origination from the mobile radio device 100, the mobile radio device 100 is in a waiting state to receive a downlink control signal of the radio channel CH1 in accordance with the procedure defined by the system.

Assume that an incoming call signal to the mobile radio device 100 arrives at the radio base station 30 from the general telephone network 10 via the barrier switch 20. These control signals are processed as communication signals 22 in the same way as audio signals by the signal processing section 31 and the encoded time piece signal forming circuit group 78. The signal passes through the signal speed conversion circuit group 51 and is transmitted to the control section 40 (FIG. 1C) via the signal assignment circuit group 52.

Then, the control unit 40 selects an empty slot 1 of the downlink time slots 1- of the radio channel CH1 addressed to the mobile radio device 100.
~, the ID of the mobile radio 1100 using e.g. SDl
Signal Ten Call Signal Display Signalman Time Slot Use Signal (
For example, 5LJ1 corresponding to SDl is used for transmission from the mobile radio device 100. In the mobile radio device 100 that receives this signal, it is transmitted from the receiving section 137 of the radio receiving circuit 135 to the control section 140. The control unit 140 confirms that this signal is an incoming call signal to its own mobile radio 100, so it causes the telephone unit 101 to emit a ring tone, and at the same time, the designated time slot SDI
, the transmission/reception intermittent controller 123 is operated to stand by at SU1, and the switches 122-1, 122-2 are started to be turned on and off. In this way, the state has shifted to a state in which calls can be made.

Note that it is clear that confidential communication can be performed for incoming calls as well as for outgoing calls. Furthermore, it is clear that the confidential conversation technology described in the present invention makes it extremely difficult for a third party who does not belong to the system to listen in without permission.

This is because the length of the time slot used for communication differs for each frame, and even if the signal of a certain time slot can be received, the exact time length is not known, and a large amount of noise will be mixed in, making it difficult for overhearing. It becomes impossible.

[Effects of the invention] As is clear from the above explanation, the confidential communication method regarding TCM signals, which has not been disclosed in the past, has become practical, so listening by a third party's radio device that does not belong to the system is now possible. , the effect of ensuring privacy in TCM communications is significant.

[Brief explanation of the drawing]

FIG. 1A is a conceptual configuration diagram showing the concept of the system of the present invention, FIG. 1B is a circuit configuration diagram of a mobile radio used in the system of the present invention, and FIG. 1C is a diagram showing the circuit configuration of a mobile radio used in the system of the present invention. Figure 2A-1 is a circuit diagram showing the internal configuration of an encrypted time piece signal forming circuit and a signal rate conversion circuit, which are the components of Figure 1C. Fig. 2A-1 is a time chart showing the signals of each part of the circuit, and Fig. 2B-1 is an internal structure of the signal speed restoration circuit and the encrypted time piece signal decoding circuit, which are the components of Fig. 1C. FIG. 2B-2 is a time chart showing the signals of each part of the circuit shown in FIG. 2B-1, and FIG. 2C is a time chart for explaining the time slots used in the system of the present invention.・Slot structure diagram; Figures 3A and 3B are spectrum diagrams showing the spectrum of call signals and control signals; Figure 3C is a circuit configuration diagram for multiplexing voice signals and data signals; Figures 4A and 4B are Flowchart 1 shows the flow of the operation of the system according to the present invention. O...Telephone network 20...Kanmon switchboard 2-1
~22-n...Communication signal O...Radio base station 1...Signal processing unit 2...Radio transmitting circuit 35...Radio receiving circuit 8...Signal speed restoration circuit group 9... Signal selection circuits 9-1 to 39-n...Signal selection circuit O...Control unit 1...Clock generator 2...Timing generation circuit 1...Signal speed conversion circuit group 1-1 to 51 -n...Signal speed conversion circuit 2...Signal allocation circuit 5...@Code decoder 76...Code assigner 7...
- Cipher storage unit 8...Encrypted time piece signal forming circuit group 9...Encrypted time piece signal decoding circuit group 1...Digital encoding circuit 2...Multiple conversion circuit 00.100-1 to 100 - n -...Mobile radio fold 0
1...Telephone unit 20...Reference crystal oscillator 21-1.121-2...Synthesizer 22-1, 1
22-2...Switch 123...Transmission/reception intermittent controller 131...Speed conversion circuit 132...Wireless transmission circuit 134...Transmission section 136...Reception mixer 138...Speed restoration circuit 175... ...Code decoder 177...Code storage section 178...Abbreviated time piece signal forming circuit 179...Encrypted time piece signal decoding circuit. 133... Transmission mixer 135... Radio receiving circuit 137... Receiving section 14]... Clock regenerator 176... Encryption device

Claims (1)

[Scope of Claims] Each radio base means (30) each covers a plurality of zones to constitute a service area, and a frame structure for moving across the plurality of zones and communicating with the radio base means. a barrier exchange means (20) for exchanging communications with each mobile radio means (100) using a radio channel carrying temporally compressed delimited signals in time slots of In the communication method, when creating the temporally compressed delimited signals to be accommodated in time slots in frames that are communicated oppositely, the time length of the delimited signals is A time-division communication privacy method for mobile communication defined in at least one of the radio base means and the mobile radio means.