JPH04150323A - Time division communication privacy calling method for mobile object communication - Google Patents

Abstract

PURPOSE:To secure the privacy of communication by ciphering the time length of each frame imparted to a transmission signal at a radio base station or a mobile radio equipment, changing the time length of each time slot and selecting whether the sequence of the signal in a time region is normal or reverse. CONSTITUTION:Switches SW (78-0)-(78-4) of a cryptographic time segment signal generating circuit group 78-1 of a radio base station are thrown to the position (a) or (b) by the output signal of a cryptography imparting device 76 including its time length. When the SW78-0 is set to the position (a) and the SW78-1 is set to the position (a), the signal is once stored at a storage circuit M1 and a reverse time read circuit RT1 reads the signal while its sequence is reversed. Moreover, when the SW78-1 is set to the position (b), the signal is delayed for a prescribed time at a delay circuit GAMMA1 and inputted to a signal speed converter 51-1-1 from the position (b) of the SW78-3. Thus, interception by a radio equipment not belonging to the system and not knowing timewise transmission sequence of the signal accommodated in the slot is prevented.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a confidential communication method for time-division communication in mobile communications. While one of the many mobile radios in the service area is setting up a radio line and communicating with the opposing radio base station, a radio that does not belong to the system is using the same radio channel and the same time slot. The present invention aims to provide a method for improving the privacy of communications by eliminating the possibility that communications may be intercepted by tuning in to communications.

[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 "'Study of mobile phone system - Proposal of time-division time compression FM modulation system-' IEICE Branch Axis RC389-1
1 Literature dated July 1989 2. Ito "Study of mobile phone system - time division time compression"
Theoretical study of M modulation system” IEICE branch axis RC889-39
October 1989 In other words, in Document 1, a transmission signal (Bestband signal) is divided into predetermined time intervals and stored in a memory circuit, and when read out, the speed is n times faster than the speed at which it is stored in the memory circuit. A carrier wave is read out in a predetermined time slot by a carrier wave, and the carrier wave is angle-modulated or amplitude-modulated with the signal accommodated by this time slot, and is built into mobile radio equipment and radio base stations in order to transmit and receive intermittently in time. A wireless receiving circuit having a receiving mixer that communicates with each other, a wireless transmitting circuit having a transmitting mixer, a synthesizer applying voltage to the receiving mixer of the wireless receiving circuit, and a synthesizer applying voltage to the transmitting mixer of the wireless transmitting circuit. A method of providing a switch circuit to intermittent the output of each applied synthesizer, synchronizing this intermittent state for both transmission and reception, and also synchronizing the same intermittent transmission and reception as above with that of a mobile radio device at a wireless base station communicating with the opposite side. and on the receiving side, in order to extract only the signal accommodated in the predetermined time slot, the radio receiving circuit is opened and closed to receive the signal, and the signal obtained by demodulation is stored in the storage circuit, and this is stored in the storage circuit. An example of a system has been reported in which a system is constructed that makes it possible to reproduce the baseband signal, which is the original signal that has been transmitted, by reading out at a low speed that is 1/n of the speed at which it is stored in this memory circuit. .

In addition, in Document 2, there is a study on adjacent channel interference and co-channel interference, which are problems when applying the TCM (time division time compression multiplexing)-FM method as described above to small zones. Possibilities of realizing the system have been shown by appropriately selecting parameters. However, there is a possibility that a wireless device that does not belong to the system may be tuned to the same wireless channel, same time slot, and intercept the communication content, and it is necessary to prevent this in order to protect privacy. However, 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 a CM (time division time compression multiplexing) signal transmitted from a wireless base station to a large number of mobile wireless devices, and a method for transmitting this signal. However, depending on the disclosed transmission method, when other radios not belonging to the system are in use, There remained a problem to be solved in that it is relatively easy to tune in to radio channels and time slots and listen in on communications.

[Means for solving the problem] - "When transmitting a CM multiplied signal, the radio base station retrieves a code from a code storage unit, and according to this, the transmission order in which C is added to the time domain to be given to the transmitted signal is normally (correctly) ), or in the reverse order (reverse), and a function is given to mobile radio devices that communicate face-to-face to instruct the type of code and the method of encryption and decoding.

[Operation] For each frame, determine whether the transmission order in the time domain (hereinafter abbreviated as temporal transmission order) of the signals accommodated in the time slot used is in the positive order or in the reverse order. Since we decided to change the code according to the instructions of the coded signal, it became possible for the TCM signal to have the same high level of encryption function as the digital signal, so the temporal transmission order of the signals accommodated in the time slot could be changed. It becomes extremely difficult for a third party's wireless device not belonging to the system, who does not know whether the order is forward or backward, to listen in, making it possible to ensure the privacy of communications.

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

In FIG. 1A, 10 is a general telephone network, and 20 is a gateway exchange for connecting the telephone network 10 and a wireless system. 30 is a wireless base station and a barrier switch 20
It includes an interface with the mobile radio, a circuit that converts the signal speed, a circuit that allocates and selects time slots, a control unit, etc.
00 (100-1 to 100-n) and a wireless transmitting/receiving circuit that transmits and receives wireless signals.

Here, between the barrier switch 20 and the wireless base station 30,
There are transmission lines for transmitting communication signals 22-1 to 22n including communication signals of communication channels CH1 to CHn and control signals.

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

Received signals such as control 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. The signal is input to the regenerator 141.

Further, a part of the output of the receiving unit 137 is applied to the decryptor 175, and the code sent from the wireless base station 30 is decoded.
0 and is input to the encrypted 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 140.
is applied to the 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, and receives the outputs of the decryptor 175 and the timing generator 142. ,
The telephone unit 101 and the control unit 140 as continuous signals.
is being entered.

In addition, the signal in the time slot, which is normally placed at the beginning of one frame, includes an uncompressed control signal that is a frame synchronization 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 input to the encrypted time piece signal forming circuit 178. This circuit has the same function as the encrypted time piece signal forming circuit group 78 of the wireless base station 30, which will be described later.

The code transmitted as a control signal from the wireless base station 30 is decoded by the decryptor 175, and the result is sent to the control unit 140.
Report to. According to the decrypted code, the control unit 140 instructs the encrypted time piece signal forming circuit 178 as to whether the time interval, timing, and transmission order of each time slot should be in the forward order or in the reverse order. The encrypted time piece signal forming circuit 178 stops the time frame of the telephone signal according to the instructions from the control unit 140 and then sends its output to the speed conversion circuit 131.

The speed conversion circuit 131 increases the speed (compression) of the communication signal (in the case of an analog signal) to a wireless transmission circuit 132 that includes a transmission mixer 133 and a transmission section 134.
is applied to

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 No. 8 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.
8 and 121-2, and selector switches 122-1, 122
'-2, and a transmission/reception intermittent controller 123 and a timing generator 142 that generate signals for switching the changeover switches 122'-1 and 122'-2, respectively. The controller 123 and timing generator 142 are controlled by the controller 140. Each synthesizer 121-1.1
21-2 is supplied with a reference frequency from a reference crystal oscillator 120.

A wireless base station 30 is shown in FIG. 1C.

N-channel communication signal 22-1 with gateway switch 20
22-n are connected to a signal processing unit 31 forming an interface through a transmission path.

Now, the communication signal 22 sent from the barrier exchange 1120
−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 88@
After the signal is converted into an encrypted signal by the encrypted time piece signal forming circuit group 78 including encoded time piece signal forming circuits 78 - 1 to 78 - n, it is sent to the signal speed converting circuit group 51 .

The output signal from the signal speed restoration circuit group 38 is decoded by an encrypted time piece signal decoding circuit group 79 including encrypted time piece signal decoding circuits 79-1 to 79-n, and then sent to the signal processing section 31. The signal is then sent to the barrier switch 20 using the same transmission path as the input signal. Of the above, barrier exchange 2
The input signal from 0 is input to the encrypted time piece signal forming circuit group 78 and divided into time intervals according to instructions from the encryptor 76.

Next, this output is sent to many signal speed conversion circuits 511 to 51.
-n is input to the signal speed conversion circuit group 51, and undergoes predetermined speed (pitch) conversion.

In addition, the signal transmitted from the wireless base station 30 to the gateway exchange 20 is inputted to the signal speed restoration circuit group 38 via the signal selection circuit 39 as the output of the wireless reception circuit 35, and after speed (pitch) conversion is performed, The signal is input to the encrypted time piece signal decoding circuit group 79. In this circuit, as a result of dividing the telephone signal into time intervals according to instructions from the decryptor 75, the telephone signal is reproduced and input to the signal processing section 31.

Next, the operations of the encrypted time piece signal forming circuit group 78 and the signal speed converting circuit group 51 are explained in FIGS. 2Δ-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. FIG. 2A-2 is a schematic diagram showing the signal processing state of each part of the circuit shown in FIG. 2A-1.

Now, in Figure 2A-1, from the left side, Figure 2A=2 (a
) A series of telephone signals from the signal processing section 31 enters the encrypted time piece signal forming circuit 78-1. The encrypted time piece signal forming circuit 78-1 includes two stages of switches 5W780.5W78-1.8W78-2. as shown in FIG. 2A-1.
Memory circuits M1, M2 . Reverse time readout circuit R1, RTR
2° delay circuit τ1. τ2 and switch 5W78-3.8W
78-4, each switch circuit 5W78-0 to 5W7
Whether 8-4 is moved to the a side or the b side is controlled by the output signal of the coder 76, including the length of time. Therefore, the series of telephone signals shown in FIG. 2A-2(a) is divided into two by the switch 5W780, and the time piece signal is either present on the 5W78-1 side or 5W78-1 as shown in FIG. 2A-2(b). Either exists on the 2nd side, and neither exists on both sides.

Next, when the switch 5W78-1 is further divided into two parts and the signal is tilted to the a side, the reverse time readout circuit R reads out the signals by reversing the order of the signals after they are once stored in the storage circuit M1.
With TR1, signal reading is performed in the completely opposite direction to that when manually operated. The operation of this reverse time readout circuit RTR1 will be explained. Simply put, recording an audio signal on a tape recorder and then playing it back is equivalent to rotating the tape in the opposite direction so that the last recorded audio is played first, and the first recorded audio is played last. do. To perform the same operation as above in a sophisticated way, do the following: That is, the timed analog telegram signal is digitized by an A/D converter and stored in a storage circuit (for example, RAM). Then, the data may be read out in the reverse order of time in the same way as the tape reader described above, and then converted into analog data again using a D/A converter.

By the above operation, the input time piece signal is converted into inverse time signal.

Also, if the signal is tilted to the b side of the switch 5W78-1, it passes through the delay circuit τ1 and arrives at the b side of the switch 5W78-3. In this case, since 5W78-3 is also tilted to the b side, the signal speed converter 51-11.

The delay time of the delay circuit τ1 is given in accordance with the time required to create the inverse time signal. In addition, switch 5W78
-1 and switch 5W78-3. The switch 5W78-2 and the switch 5W78-4 operate synchronously.

The above has explained the case where the signal from the switch 5W78-0 flows to the a side, but when the signal flows to the b side of the 5W78-0, the same processing as above is performed by the signal from the coder 76, and the time frame is stopped. It is determined whether the telephone signal received is to be detimed and enters the signal rate converter 51-1-2.

The time piece signals which are the outputs of these switches 5W78-3, 5W78-=1 are shown in FIG. 2A-2(C), and these signals
-2 and are subjected to time compression, respectively, to the second A-2.
The signal shown in FIG. 2(d) is output. The outputs are mixed to form one series of pressure line signals shown in FIG. 2A2(e), and are input to the signal assignment circuit group 52.

In the time piece signals shown in Figure 2A-2, the signals covered with diagonal lines on the upper right are signals that have not been converted to inverse time, and the signals covered with diagonal lines on the lower right are time pieces that have been converted into inverse time. Showing a signal.

Next, the operations of the signal speed restoration circuit group 38 and the encrypted time piece 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 group 3 in Figure 1C.
8 and the encrypted time piece signal decoding circuit group 79, only the signal speed restoration circuit 38-1 and the encrypted time piece signal decoding circuit 79-1 for the communication channel number 1 are selected. The same operation is performed in ~ n, so it is represented by the call monitor number 1. 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 shown in FIG. 2B-2 (a>) is input to the signal speed restoration circuit 38-1 from the right side of FIG. 2B-1. As shown in Figure 1, a kind of switch 5W38 and signal speed restorer 3
Whether the switch 5W38 installed on the input side is switched to the a side or the b side, the timing signal is sent to the timing generation circuit 42. This is carried out cyclically in synchronization with the time slot within the frame, and the time piece signal shown in FIG. 2B2(b) is obtained at the a and b side terminals of the switch 5W38. This time piece signal containing the compressed telephone signal within each frame is processed by a signal rate restorer 38-1-1.38-1-
2 to restore the original speed to obtain the restored time piece signal of FIG. 2B-2(C). These are sent to the encrypted time piece signal decoding circuit 79-1.

The encrypted time piece signal decoding circuit 79-1 includes a plurality of switches 5W79-1 to 5W79-4, as shown in FIG. 2B1.
Memory circuit M1. M2. Reverse time series circuit R-d R3, RTR
4 and a delay circuit τ3°τ4, whose operation is similar to that of the encrypted time piece signal forming circuit 78- shown in FIG. 2A-1.
This is the opposite of 1, and the original telephone signal is reproduced.

The output of the signal speed restorer 38-11 in FIG. 2B-2(C) is the switch 5W7 of the encrypted time piece signal decoding circuit 79-1.
It arrives at 9-1. This circuit is controlled by a signal from the decryptor 75, and according to this signal, if the switch 5W791 is turned to the a side, the incoming signal is first applied to the memory circuit M3 and stored. be served. The temporal nature of this output signal is inverted by the reverse time reading circuit RTR, and since the signal is in the state where the switch 5W79-3 is on the a side, it is input to the signal processing section 31. Also 5W
When 79=1 is on the b side, this is because there is no temporal reversal in the transmitted signal, and the signal is input to the signal processing unit 31 after being given a delay time τ by the delay circuit τ3.

The above may be the output signal from the signal speed restorer 38-1-1, or the output signal from the signal speed restorer 38-1-2 may have been processed in the same manner as above, as shown in FIG. 2B-2(d). Obtain a time piece signal. These output signals are mixed and output as a series of telephone signals to the signal processing section 31, but in this telephone signal, the original signal is faithfully reproduced without any discontinuity or overlap. .

Here, in each time piece signal of Fig. 2B-2, the 2A-
As in Figure 2, diagonal lines are drawn upward to the right or downward to the right, but the upward diagonal lines to the right are in the positive order, and the downward diagonal lines to the right are in the reverse order, and each time segment signal includes a telephone signal. It is shown that.

Now, the control of the radio reception circuit 35 or the output of the call signal is performed by the time slot 1 to the signal selection circuit 3 which selects signals separately.
The signal is input to a signal selection circuit group 39 including 9-1 to 39-n, where the speech signal is separated corresponding to each speech channel C1-11 to CHn. This output undergoes signal speed (pitch) restoration in a signal speed restoration circuit group 3B including signal speed restoration circuits 38-1 to 38-n provided for each channel, and then is input to the signal processing section 31. , after undergoing 4-wire to 2-wire conversion, this output is sent as a communication signal 22- to the barrier switch 20.
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, and in reality, for example, a CCD (Charge C
), BBD (Buc
ket Brigade Device) can be used, and the memory used in television receivers and tape recorders that compress or expand the time axis of conversation can be used (References: Koita et al. ``Time axis of conversation (Nikkei Electronics, July 26, 1976, pp. 92-133).

C0D1') BBD illustrated in the signal speed conversion circuit group 51
As described in the above-mentioned document, a circuit using
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.

The control or audio signals outputted from the barrier switch 20 via the signal processing section 31 are input to the signal speed conversion circuit group 51, where speed (pitch) conversion processing is performed and the signals are converted into signals for each time slot. signal assignment circuit group 52 that assigns
is applied to The 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 receives timing information from the timing generation circuit 42 given by instructions from the control section 40. Then, the signal in the buffer memory is read out 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 assignment circuit group 5.
2 and are given time slots in a predetermined order. SDO, SDl in Figure 2C (a)
, 802-, and SDn indicate that the speed-converted communication signals are allocated to each time slot.

Note that each frame F1. F2. F3. The first time slot SDO of .
Contains call signals and/or control signals in response to calls from. 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 (a), in the wireless transmission circuit 32, the time slots SDO, SD
A signal forming one frame from 1 to SDn is applied to the modulation circuit. 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 described above, the control signal transmission between the mobile radio device 100 and the mobile radio device 100 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. It 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,
Low frequency side (250Hz >) and high frequency side (38501-1
2) 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 converted into a signal, 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 analog signals, but if a digital data signal is used as a control signal, it is also possible to digitally encode the audio signal and time-division multiplex the two to transmit. The circuit configuration of is shown in FIG. 3C. In this system, an audio signal is digitized by a digital encoding circuit 91, and then it and a data signal are digitized by a multiplex conversion circuit 9.
This is an example of a case where the signal is multiplexed by 2 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 indicate transmission signals addressed to the radio base station 30 from the mobile radios 10'O-1, 100-2, . . . , 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 1110O to the radio base station 3
If you want to make a call to 0 or make an emergency communication, press S U to Time Thrower+, which is always installed at the beginning of each frame.
Use O.

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 Sun. The signal or speech signal is separated and output. Each of these signals is input to the signal speed restoration circuit group 3B. As previously 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. It will be sent to the gateway exchange 820.

Hereinafter, the manner in which the signal space used in the present invention is transmitted will be explained 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 after performing 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 the signal speed conversion circuit group 51 (FIG. 1C) passes through the signal speed conversion circuit group 51 (FIG. 1C). That is, if the audio signal is converted 15 times as described above, the frequency distribution of the signal is as shown in Figure 3B.
This means that it has been expanded to 4.5kH2 to 45kl-12.

Here, the frequency distribution of the signal is expanded, but the shape of the waveform is simply stretched along the frequency axis.
It is necessary to keep in mind that the waveform itself does not change.

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 4.0kl-1
z) and call signal CH1 (SD at 4,5~45kHz7)
1) is accommodated in a time slot, say SDl. The same applies to the audio signals accommodated in the other time slots SD2 to SDn.

That is, time slot SDi (i=2°3,
, n) accommodate a control signal (0.2 to 4.0 kHz) and a communication signal C1-1i (4.5 to 45 kHz). However, the signals in each time slot are arranged in chronological order, and the signals in multiple time slots are not applied to the wireless transmission 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±45kl-1z. However, foI, 1. is the radio carrier frequency. If there are a plurality of wireless channels given to the system, the speed-up 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. Let f be the frequency interval of the plurality of wireless channels. , and let fl be the maximum signal speed due to the above-mentioned speed increase of the audio signal, then the following inequality must hold between the two considerations.

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.

Further, the control signal input from the mobile radio device 100 to the radio base station 30 is input to the radio reception circuit 35, but a part of the output is input to the control unit 40, and the other part is input to 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 latter control signal 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. It is sent to barrier exchange t120.

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 flowcharts 1 to 1 shown in FIGS. 4A and 4B.

When the mobile radio device 100 is powered on, the first
In the wireless receiving circuit 135 in Figure B, the downlink (wireless base station 30
→Mobile radio 100) Radio channel (channel Cl-1
1)).

If the system is provided with multiple radio channels, 1) the radio channel exhibiting the maximum received input electric field) the radio channel indicated by the control signal contained in the radio channel; A radio channel (hereinafter referred to as channel CH1), such as a channel with an empty time slot among the slots, enters the reception state according to the procedure determined by the respective system. This corresponds to each frame F1. 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 also moves the switch 122-1 to the synthesizer 121-1 side and fixes it. is in a state of

Therefore, when the receiver of the telephone unit 101 is off-hook (starting calling) (3201, FIG. 4A), the synthesizer 121-2 of FIG. A control signal to be generated is received from the control unit 140.

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 wireless channel CHI. This control signal has a frequency band shown in FIG.
It is sent using O.

The transmission of this control signal is limited to the time thrower +-S U O, and is sent in bursts, and no signal is transmitted during the time slot, so that it does not adversely affect other communications. However, if the speed of the control signal is relatively slow,
Alternatively, if the amount of information in the signal is too large to be accommodated in one time slot, it is transmitted using the same time slot in the next frame one frame later or roughly.

Specifically, the following method is used to capture the time thrower +-S U O. The control signal transmitted from the radio base station 30 includes a synchronization signal and a subsequent control signal, as shown in FIG.
By receiving this, frame synchronization becomes possible. This control signal also includes the current time
Contains control information such as slots and unused time slots (empty time slot display). Depending on the system, the time slot sDr <r=1.2°・
..., n) may contain only synchronization and speech signals when used by other communications, or even in such cases, unused time slots usually contain synchronization and control signals. is included, and by receiving this control signal, the mobile radio device 100 can determine which time
It is possible to know which page sends a call signal using the slot.

Note that if all time slots 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, empty slots 1 to 1 may not be displayed in any of the time slots, in which case the audio multiplex signal SDI that follows.

SD2. ..., it is necessary to search for the presence of SDn one after another and check for empty time slots.

Now, returning to the main topic, the mobile radio device 100, which has received the control information sent from the radio base station 30 by one of the methods described above, determines in which time slot it should transmit the call control signal. It is possible to make decisions including timing.

Furthermore, at this point, the mobile radio device 1
00 has received the cipher information, and when communication is started, the control unit 140 can enter a standby state for the cipher to be given to the encrypted time piece signal forming circuit 178. However, confidential conversations will not be made until the call has started.

Assuming that the time slot SUO for uplink signals is an empty slot I, it is decided to use this empty time slot, and the necessary timing is determined from the response signal from the radio base station 30 by sending out a control signal for calling. It is possible to extract a burst control signal and send out a burst control signal.

If there is a call from another mobile radio at the same time, the call signal will not be properly transmitted 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 other part of the time slot, but rather uses only the first half for some mobile radios and only the second half for other mobile radios. There is a method that allows you to use .

In other words, the portion of the time slot used 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 a time period within that one time slot. It is a way of giving. Another method is to create many types of frequencies for control signals, group a large number of mobile radios, and give these to each group. According to this method, even if control signals of different frequencies are transmitted simultaneously using the same time slot, no interference will occur at the radio base station 30. The above two methods may be used separately, or when used together, 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 ID (identification number) of the mobile radio device 100 is detected (3202>, the radio base station 30
The control unit 40 of the mobile radio device 100 detects the ID (identification signal) of the mobile radio device 100 (5202) and confirms the ID.
The communication channel designation signal and mouth number 8 information necessary for making a call to the mobile radio device 100 are sent to the downlink time slot S.
Transmit to the mobile radio device 100 using DO (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 report is sent to the radio base station 30.
(3205>) and wait for a dial tone to be sent (3206>).

The radio base E30 naturally expects this and is waiting for reception, and upon receiving the slot switching completion report (S207>
, sends a call signal together with the ID of the mobile radio device 100 to the gateway exchange 20 (3208>.In response, the barrier exchange 1N20 turns on the necessary switches among the switch group included in the barrier exchange 8120. A dial tone is sent to the wireless base station 30 (3210. FIG. 4B).

This dial tone is transferred by the radio base station 30 using time slot SD1 (S211>, and the mobile radio 11100 confirms that the communication path has been set (S212>). Radio 1
Since a dial tone is heard from the handset of the telephone section 101 of 00, transmission of a dial signal begins. This dial signal is speed-converted by a speed conversion circuit 131 and is sent to a radio transmission circuit 13 including a transmission section 134 and a transmission mixer 133.
2 using uplink time thrower l-8U1 (32M3). Thus, the transmitted dial signal is received by the radio receiving circuit 35 of the radio base station 30. This radio base station 30 already responds to the calling signal from the mobile radio 100, gives the time slot to be used, and operates the signal selection circuit group 39 and signal allocation circuit group 52 of the radio base station 30. Then, it receives the uplink time slot SU1 and shifts to the state of transmitting the signal of the downlink time slot SD1. Therefore, the dial signal transmitted from the mobile radio 100 passes through the signal selection circuit 39-1 of the signal selection circuit group 39, and then passes through the signal speed restoration circuit group 38 to the encrypted time piece signal decoding circuit group 79. Here, the original transmission signal is restored and transferred to the gateway exchange 20 as a call signal 22-1 via the signal processing unit 31 (S214), and a call path to the telephone network 10 is set (3215>).

On the other hand, the input signal from the barrier exchange 120 (initial control signal,
When a call is started, the call signal) is polarized in the encrypted time piece signal forming circuit group 78 via the signal processing unit 31 in the radio base station 30, and the polarized signal is polarized in the signal speed converting circuit group 51. After undergoing speed conversion at , the time slot SD1 is assigned by the signal assignment circuit 52-1 of the signal assignment circuit group 52. and wireless transmission circuit 32
Time thrower of the radio channel downstream from L-SD
It is transmitted to the mobile radio device 100 using I.

In the mobile radio device 100, the radio zi! ? It is waiting for reception in time slot SD1 of channel CH1, and is received by radio reception circuit 135, and its output is sent to speed restoration circuit 13.
8 is input. 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 (S216>).

Furthermore, as described above, the radio base station 30 and the mobile radio a100 are ready for the secret conversation, and once the conversation starts, it is immediately executed.

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 control communications between the radio base station 30 and the mobile radio device 100 that are performed before the start of a call, such as the above-mentioned call channel assignment.
I omitted the explanation because it is not very practical.

The call is terminated by on-hooking the handset of the telephone section 101 of the mobile radio 100 (3217>), and the end-of-call message g and the on-hook signal from the control section 140 are sent to the speed conversion circuit 1.
31 via the wireless transmission circuit] 32 to the wireless base station 30 (3218>, the control unit 140 stops the operation of the transmission/reception intermittent controller 123, and switches 122-1 and 122-2, respectively. It is fixed to the output ends of synthesizers 121-1 and 121-2.

On the other hand, in the control unit/40 of the radio base station 30, the mobile radio t
When the call termination signal is received from 1100, the call termination signal is transferred to the gateway exchange 20 (5219), and the switch group (not shown) is turned off to terminate the call (S220).
. At the same time, three signal selection circuit groups and signal allocation circuit group 52 in radio base station 30 are opened.

In the above explanation, control signals are exchanged between the radio base station 30 and the mobile radio device 100 by the signal rate conversion circuit group 51. Although it was explained that the signal speed restoration circuit group 38 etc. are not passed through,
This is for convenience of explanation, and communication can be carried out without any problem even through the signal speed conversion circuit group 51, signal speed restoration circuit group 38, control signal speed conversion circuit/18, or signal processing section 31, as with audio signals. is.

(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 on the radio channel CI-11 in accordance with the procedure determined 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 transmitted as communication signals 22 to the signal processing unit 31.18 time piece signal forming circuit group 78. It passes through the signal rate conversion circuit group 51 and is transmitted to the control unit 40 (FIG. 1C) via the signal allocation circuit group 52.Then, the control unit 40 selects the downlink time slot of the radio channel CH1 addressed to the mobile radio IJ100. I of the mobile radio 1100 using an empty slot l~, for example SDl.
D signal 10 Incoming call signal display Signaler time slot usage signal (for example, SUL corresponding to SDI is used for transmission from mobile radio 100). In the mobile radio device 100 that receives this signal, the signal is transmitted from the receiving section 137 of the radio reception/low-reception circuit 135 to the control section 140 . The control unit 140 confirms that this call signal is an incoming call signal to its own mobile radio 100, so it makes the telephone unit 101 emit a ring tone and at the same time calls the designated time slot SD1.
．． The transmission/reception intermittent controller 123 is operated to stand by at SU1, and the switches 1221 and 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 temporal transmission order of signals accommodated in fixed time slots is changed in accordance with the instructions of the encrypted signal for each frame. Even if the signal can be received, it is not known whether the time domain is inverted or not.

Therefore, since the same state continues in the next frame signal, a large amount of noise is mixed in, making it impossible to listen to the signal.

[Effects of the Invention] As is clear from the above explanation, the secret method for TCM signals, which has not been disclosed in the past, has become practical, making it difficult for a third party's radio equipment that does not belong to the system to listen in. The effect of being able to ensure privacy in TCM communication is significant.

[Brief explanation of the drawing]

Figure 1A is a conceptual block diagram showing the concept of the system of the present invention, Figure 1B is a circuit diagram of a mobile radio used in the system of the present invention, and Figure 1C is a wireless base used in the system of the present invention. Figure 2A-1 is a circuit diagram showing the internal configuration of the encrypted time piece signal forming circuit and signal speed conversion circuit, which are the constituent elements of Figure 1C. Figure 2A-2 is the circuit diagram of 2Δ- A time chart showing the signals of each part of the circuit shown in Fig. 1. Fig. 2B-1 is a circuit configuration diagram showing the 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 1 to 1 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. Figures 3A and 3B are spectrum diagrams showing the spectrum of speech signals and control signals; Figure 3C is a circuit configuration diagram for multiplexing voice signals and data signals; Figures 4A and 4B are 3 is a flow chart showing the flow of operation of the system according to the invention. 10... Telephone network 20... Gateway switchboard 22
-1 to 22-n...Communication signal 30...Radio base station 31...Signal processing section 32
...Wireless transmission circuit 35...Wireless reception circuit 38.
... Signal speed restoration circuit group 39 ... Signal selection circuits 39-1 to 39-n ... Signal selection circuit 40 ... Control section 41 ... Clock generator 42 ... Timing generation circuit 51 ... - Signal speed conversion circuit group 51-1 to 51-n...Signal speed conversion circuit 52...
Signal allocation circuit 75... Encryption decoder 76... Showa No. I4 giver 77... Encrypted time piece signal forming circuit group 79... Encrypted time piece signal decoding circuit Group 91...Digital encoding circuit 92...Multiple conversion circuit 100.100-1 to 100-n...Mobile radio device 10
1...Telephone unit 120...Reference crystal oscillator 1
21-1.121-2...Synthesizer 122-1.
122'-2...Switch 123...Transmission/reception intermittent controller 131...Speed conversion circuit 132...Wireless transmission circuit 133...Transmission mixer 134...Transmission section 135
... Radio reception circuit 136 ... Reception mixer 137.
...Receiving section 138...Speed restoration circuit 141.
...Tarlock regenerator 175...Code decoder 176...Code adder 1
77... Encrypted storage unit 178... Encrypted time piece signal forming circuit 179... Encrypted time piece signal decoding circuit M1-M4... Memory circuit R1-RTR4... Reverse time series successive circuit SW38 . 5W78 O~5W78 W79 1~5W79 4...Switch τ1-~τ4...Delay circuit.

Claims (1)

[Scope of Claims] Each radio base means (30) each covers a plurality of zones and constitutes a service area, and a frame for moving across the plurality of zones and communicating with the radio base means. mobile using barrier exchange means (20) for exchanging communications between each mobile radio means (100) using a radio channel carrying time-compressed delimited signals in the time slots of the configuration; In the system communication method, when creating the temporally compressed delimited signals to be accommodated in each time slot in frames that communicate oppositely, the temporally compressed delimited signals to be accommodated in the delimited signals are at least one of the radio base means and the mobile radio means that communicates with each other whether the order of the signals in the time domain is the same normal order as the speech signal or the reverse order from the speech signal; On the one hand, a time-division communication secret method for mobile communication is defined.