JP2644723B2 - Communication device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exchange system for exchanging and connecting information such as voice, data, and images, and more particularly, to a communication terminal device such as a telephone or a data terminal device. The transmission path between the switching devices
Enables wireless communication, enables high-quality transmission over low-quality cables, or allows multiple terminals to be connected and connected to the same cable, and allows individual simultaneous communication The present invention relates to a switching system using spread spectrum modulation.

[Background of the Invention]

Taking a wireless telephone system as an example, a car telephone and a wireless telephone have been put into practical use. In the former, phase modulation or frequency modulation is employed as a modulation method of information in a wireless part. For example, “New Edition Mobile Communication System” published by Kagaku Shimbun (published on May 10, 1979)
(Referred to as Reference 1) Pages 239-260 provide an overview.

In the latter case, generally, a cable is drawn from a telephone station to the inside of the subscriber's premises, and the wireless system is used in the inside of the subscriber's premises, and frequency modulation is often used. (Reference 1. pp. 294-301) Also, trial systems that are relatively close to the use environment targeted by the present invention have been tried,
Since the phase modulation system is adopted and the exchange is also a crossbar system, the problems of confidentiality, noise resistance, and interference resistance have not been solved. (Ref. 1, pages 291 to 294) A mobile radio system employing a digital switching system is also found in, for example, JP-A-59-58927, but employs spread spectrum modulation which is the object of the present invention. No consideration is given to the confidentiality between the terminal device and the noise resistance.

[Object of the invention]

An object of the present invention is to improve an information transmission method between a terminal device and a switching device.

That is, an object of the present invention is to enable wireless communication between a communication terminal device and a switching device, to enable high-speed digital transmission using a lossy, noisy line, or to connect a plurality of terminal devices to the same line. An object of the present invention is to provide an exchange system which enables parallel simultaneous connection to perform individual simultaneous communication, and has a high level of secrecy, strong against eavesdropping, and strong against interference by electromagnetic waves.

For example, by making the connection between a telephone or data terminal device in an office building and the exchange device wireless, the installation work of the exchange device and the terminal device (including the telephone) can be simplified, and the wiring change by the rearrangement in the office can be performed. It is an object of the present invention to eliminate the need for facilities such as piping for indoor wiring as well as to eliminate the need for such facilities.

Another object is to enable high-speed digital transmission using a local cable between a terminal device and a switching device designed for analog voice.

In addition, connect multiple terminal devices to one cable,
It is also an object to simultaneously perform individual communication by multiplexing technology.

Furthermore, by combining the technology for solving the problems caused by the movement of the terminal device, such as the tracking switching technology and the automatic transmission power control technology on the mobile terminal device side, it can be applied to mobile communications such as car phones as it is. The purpose is also to make it possible.

[Summary of the Invention]

The present invention introduces spread spectrum modulation / demodulation technology into information transmission between a communication terminal device and a time division multiplexing switching device, and makes the spread spectrum modulation / demodulation device controlled by a central control device of the switching device, thereby achieving economical efficiency. It is intended to realize a simple switching system, especially a wireless switching system.

When the connection between the terminal device in the office and the switching device is made wireless, the terminal device may be considered to be stationary in use, and the problem caused by the movement of the terminal device during communication such as mobile radio is a problem. I do not think.

Also, the distance between the antenna of the terminal device and the antenna of the switching device can be made substantially equal by a method such as installing the antenna in each room or laying a leaky coaxial cable on the ceiling or the like. Thus, the spread spectrum communication can be performed without controlling the transmission power for compensating the distance difference from the antenna.

Furthermore, the reach of radio waves transmitted from one antenna can be limited to a relatively narrow range, such as in the same room or on the same floor, so that weak radio waves can be used and radio waves can be used effectively.

The pseudo-noise code for spread-spectrum modulation and demodulation is not so many in the same system when considering offices.On the other hand, the difficulty in deciphering communications is not as high as that in military communications. Relatively simple codes can be used since they are not considered required. That is, the spread spectrum modulator / demodulator can be simplified.

Based on such a premise, the present invention provides a terminal device and a switching device each with a transceiver including a spread spectrum modulator / demodulator, a pseudo-noise code generator, an antenna, etc., for example, from the reach of radio waves transmitted from each antenna. Within a certain fixed area, non-overlapping pseudo-noise codes are individually provided at least for each terminal device.

In the case of transmission from the terminal device, the terminal device transmits a calling signal subjected to spread spectrum modulation with the pseudo noise code given to the terminal device itself, and the demodulator of the switching device captures and captures this signal. The pseudo-noise code or the information transmitted by this code is transferred to the central control of the switching equipment, which identifies the calling terminal equipment. The central controller sets the pseudo noise code of the calling terminal in the spread spectrum modulator of the switching device, and sets a downlink channel to the calling terminal.

In the case of an incoming call to the terminal device, the called number is sent to the central control unit in the switching device. The called terminal device is identified from this number, and the corresponding spread spectrum modulator of the switching device side is used. Then, the pseudo-noise code of the demodulator is set to the code of the called terminal device, and the called terminal is called by transmitting the control signal of the terminal device on this channel and transmitting it.

In both the case of calling and the case of receiving, after the channel setting between the terminal device and the switching device by the above-described method, for example, in the case of voice, an 8-bit companded PCM code of 8,000 samples / sec is given to the terminal device. The spectrum is spread by a pseudo-noise code and transmitted / received.

In this manner, a communication system with high confidentiality and strong interference resistance can be realized.

Although some modulation methods such as direct sequence and frequency hopping are considered for the spread spectrum, the present invention is not affected by the modulation method.

(Example of the invention)

FIG. 4 shows an example of a communication system in a building, in which a main exchange 300 is placed on a cable 400 from the outside, for example, in the lower area where the office line enters, and a child exchange 200 is installed on each floor. And each child exchange 200
The components are connected to each other via a node device 610 by a fiber optic cable 600, for example. The main switching device 300 and the child switching device 200 include an antenna 500, for example, a leaky coaxial cable,
Connected to.

The terminal device 100 is a voice / data combined terminal device, has an antenna, and the switching device 200 or
It is connected to 300 wirelessly.

In this communication system, since the switching device 200/300 and the terminal device 100 are wireless, the installation work is
The installation of the switching devices 200/300, the connection with the node device 610, the connection with the external cable 400, the installation and connection of the antenna 500, and the wiring between the switching devices 200/300 and the terminal device 100 become unnecessary.

Further, if an optical fiber is used for the cable 600 and time-division multiplexing is performed, it is not necessary to route a large amount of cable, and the construction is greatly simplified.

FIGS. 1 and 2 show the main switching device 30 in FIG.
0 or the first of the parts related to the present invention
And FIG. 3 shows a terminal device.
One embodiment of 100 is shown.

Hereinafter, the first embodiment will be described in detail with reference to FIG.

α. First Embodiment In this embodiment, as shown in FIG. 1, a modem 210 is provided for the number of simultaneous calls / communications according to the traffic.
The modulator / demodulator 210 has a feature that operates at a low speed because it handles only information for one line.

The terminal device 100 and the switching device 200 or 300 in FIG.
Information to and from ISDN, the Integrated Services Digital Network (Integrated Services Digital Network)
ervices Digital Network), a 64 kb / s channel B for voice or data,
It consists of a 16 kb / s channel D for data and signals. FIG. 5 shows the relationship between the channels B and D on the highway in the switching device and on the transmission path between the switching device and the terminal device. FIG. 5 (a) shows a case where B + D information is exchanged with the terminal device in the case of voice centering, and FIG. 5 (b) shows a case where B + B + D information which is considered to be the ISDN standard is exchanged. .

The frame shown in Fig. 5 (α) is the time for one sample in which sound is sampled at a rate of 8000 samples per second.
This corresponds to 125 μs. In this frame, n time slots are time-division multiplexed, and one time slot, for example, TSo is composed of 8 bits. When transmitting the data to the transmission path to the terminal device, two bits as the D channel are added, the data is expanded temporally, and the data is transmitted at a speed of 80 kb / S. The information sent from the terminal is
After removing the two bits of the channel, it is temporally compressed and inserted into a designated time slot on the highway.

FIG. 5B shows the case of B + B + D, where the signal speed with the terminal device is 144 kb / s. In the drawing, but are assigned a time slot TS ₀ and TS ₁ as a B + B, not necessarily the adjacent time slots, may also be for different highways.

In this embodiment, the case of FIG. 5 (α) will be described for simplicity.

First, when not in a call / communication state, the switching device of FIG.
In 200/300, central controller 240 controls modem 210 via signal reception and distribution device 230 to prepare for call detection. That is, the central controller 240 designates the empty modem 210 and, if preamble synchronization is adopted, calls should be detected to the pseudo-noise code generator (hereinafter referred to as PN generator) 213 of the modem 210. A preamble code and a pseudo-noise code (hereinafter referred to as a PN code) assigned to the terminal device 100 are designated, and an instruction is given to drive the spread demodulator 212 with the preamble code for synchronization acquisition. In detecting a call from a plurality of terminal devices, the central control unit 240 waits for a sufficient time for the demodulation unit of the modem 210 to synchronously capture, and sets the demodulation unit to a terminal device 100 that may call the demodulation unit. Driving is performed by sequentially switching with a brimble code and a PN code, and a call is detected.
In this case, a plurality of calls can be detected simultaneously using a plurality of modems 210.

That is, in the known switching device, the central controller spatially scans the line interface circuit, whereas in the switching device of the system of the present invention, the central controller 240 uses the modem 210 and the spread demodulator. Scan by switching the preamble code and PN code of 212 sequentially,
When synchronization acquisition is performed, it is regarded as a call.
If the PN code given to the same terminal device is different between the upstream (transmission from the terminal device to the switching device) and the downstream (transmission from the switching device to the terminal device), the spread demodulator 21
The PN code set to 2 is an upstream code.

Next, when the terminal device 100 is not in a call / communication state, only the spread demodulator 112 in FIG. 3 performs the synchronization acquisition operation with the downlink preamble code of the own terminal device generated by the PN generator 113. I am preparing to receive.

α.1. Transmission operation First, the transmission operation of the terminal device will be described with reference to FIGS.
This will be described with reference to the flowchart in FIG.

Increasing the handset in #m ₁ terminal apparatus 100 of FIG. 4 (FIG. 6 601), the third controller 140 shown in FIG detects this (not shown). The control device 140 is the interface circuit 1
The PN generator 113 is instructed to supply the upstream preamble code to the spread modulator 111 via 50, and the spread modulator 111 sends out a preamble signal. The preamble signal that has been spread-spectrum-modulated with the uplink preamble code of the terminal device itself is amplified to a predetermined power by the transceiver 120 and transmitted from the antenna 130 (FIG. 6, 602).

The preamble signal transmitted from the antenna 130 is received by the antenna 500 shown in FIG. 1, amplified by the transceiver 220, and input to the spread demodulators 212 of all the modems 210.

Now, assuming that the spread demodulator 212 of the No. 1 modem 210 has been set to the uplink preamble code of the Δm ₁ calling terminal device by the control for call detection of the central control device 240, The circuit 214 operates and acquires synchronization (the sixth time).
(Fig. 611).

In the switching equipment 200/300, the synchronization circuit of the No. 1 modem 210
From 214, a signal indicating that synchronization has been acquired is sent to the central control unit 240 through the signal reception / distribution unit 230. The central controller 240 knows that spread demodulator 212 of No.1 modem 210 is captured synchronization in the uplink preamble code #m ₁ terminal device identifies that #m ₁ terminal originates a call (Sixth Figure,
612).

The central control unit 240 is a spread modulator of the No. 1 modem 210.
211 to be set down preamble code and the PN code #m ₁ terminal apparatus 100 to the PN code generator 213 (Figure 6, 6
13). As a result, the spread modulator 211 transmits the downlink preamble signal through the transceiver 220 and the antenna 500.

In the ♯m ₁ calling terminal device 100, this preamble signal is received by the spread demodulator 112 through the antenna 130 and the transceiver 120, and is synchronously captured under the control of the synchronization circuit 114 (FIG. 6, 60).
3). This uplink that it has captured downlink both synchronous, since #m ₁ terminal device 100 can confirm switches the spread spectrum code of the uplink from the preamble code to the PN code for communication, thereafter, synchronization circuit 114 synchronized Continue tracking. Prior to the switching, the terminal device 100 sends the switching signal on the preamble signal and sends it to the spread demodulator 212 of the switching device 200, and the spread modulator 111 on the terminal device side and the spread demodulator 212 on the switching device are synchronized with each other. Switching to the PN code is performed (FIGS. 6, 604 and 615).

In the switching device 200, when the spread demodulator 212 switches from the preamble code to the communication PN code, the terminal device 10
Even if it is 0, it is confirmed that the downlink preamble signal has been captured synchronously, a switching instruction signal is added to the downlink preamble signal and sent, and the downlink is switched from the preamble code to the PN code for communication in the same procedure as the uplink (FIG. 6, 616, and FIG. 6, 605).

By the above operation, a bidirectional line between the terminal device 100 and the switching device 200 is set, so that the switching device 200 sends a dial tone to the calling terminal device (FIG. 6, 61).
7) Enter dial monitoring. The subsequent operation of the switching device is performed in the same manner as the operation of the known switching device.

After the line is set, communication and high-speed data are performed using the B-channel, and control signals and low-speed data are performed using the D-channel as described with reference to FIG.

The operation after transmission of the dial tone will be briefly described with reference to FIGS.

The central control unit 240 is a spread modulator of the No. 1 modem 210.
When it is detected from the PN generator 213 that the spreading code of 211 has been switched from the preamble code to the PN code through the signal receiving and distributing device 230, the dial tone transmitting circuit (not shown) and the No. 1 modem 210 are transmitted, for example. An empty time slot is selected and connected through the highway 261, the switching network 250, and the reception highway 260. Here, the switching network 250 may be a time switch, a space switch, or a combination of both.

When the above connection is made, the central controller 240 stores the selected time slot on the reception highway 260 in the time slot memory 215-2 in the buffer memory 215 in the No. 1 modem 210 through the signal reception and distribution device 230. Let it. Thereafter, in the time slot, the time slot switch 215-1 is closed, and the 8-bit encoded dial tone is received by the shift register 215-3. The 8-bit information input to the shift register 215-3 is immediately transferred to another shift register 215-4, and the shift register 215-3 prepares for receiving the signal of the time slot of the next frame.

After the 8-bit information transferred to the shift register 215-4, a total of 2 bits of data and control bits are added under the control of the central control unit 240 (the hatched portion of the shift register 215-4 in FIG. 1). As shown in FIG. 5 (α), the signal is sent to the spread modulator 211 at a speed of 80 kb / s, and Δm ₁
The signal is spread-spectrum modulated by the downlink PN code given to the terminal device, amplified by the transceiver 220, and transmitted from the antenna 500.

In #m ₁ terminal apparatus 100, received by the antenna 130 as shown the signal in FIG. 3, and Zohaba with transceiver 120, and inputs the spread demodulator 112.

The spread demodulator 112 demodulates with the downlink PN code of the own terminal device (♯m ₁ ), takes out only the signal of the B channel via the interface circuit 150 under the control of the control device 140, and outputs the predetermined signal to the PCM demodulator 162. Converted to speed and sent.
The PCM demodulator 162 converts the 8-bit code sent at a rate of 8000 samples / second into an analog signal, operates the receiver 164 with a predetermined power, and makes the calling party hear a dial tone.

When the caller dials the number of the connection destination with the dial 165, the control device 140 detects this via the interface circuit 150, and sends the D channel of FIG. 5 to the spread modulator 111 via the interface circuit 150. After inputting with a predetermined code at the position of, and performing spread modulation with the uplink PN code,
The signal is amplified by the transceiver 120 and transmitted from the antenna 130.

On the exchange side, this radio signal is transmitted to the antenna 50 of FIG.
Spread demodulator 212 after received at 0 and amplified by transceiver 220
And the signal is sent to the shift register 216-4. The control signal is input to a hatched portion in the figure, and this portion is read by the central control device 240 via the signal receiving and distributing device 230.

After receiving the predetermined dialing, the central control unit 240 identifies the called terminal device, performs a paging operation, and then performs an idle channel with the calling terminal device, that is, an idle channel on both the transmitting and receiving highways of the calling terminal device. A time slot, a free time slot on both the transmitting and receiving highways on the called terminal side is selected, and a time slot memory 215-2 of the calling and called terminal apparatus 210 is transmitted through the signal receiving and distributing device 230.
Write the selected time slot number to 216-2.
On the other hand, the switching network 250 is controlled to connect the calling time slot and the called time slot.

α.2. Incoming call operation Next, the call operation of the called terminal device will be described with reference to FIGS.
And the flowchart of FIG.

In FIG. 1, the central controller 240 dials (called number)
(711 in FIG. 7), it identifies which terminal device the number belongs to. Now, assuming that the called terminal device is ♯mi in FIG. 4, the central control unit 240 is able to call the called terminal device ♯mi.
The No. n modem 210 is selected and captured (FIG. 7, 712).

Subsequently, the central controller 240 transmits the preamble and the communication PN code assigned to the called terminal device ♯mi, respectively, via the signal reception / distribution device 230 to the PN generation of the No.n modulation / demodulation device 210. 7 (FIG. 7, 71)
3). As a result, spreading modulator 211 starts transmitting a preamble signal (714 in FIG. 7), and spreading demodulator 212 prepares for reception of an uplink preamble signal from the ♯mi terminal device. The preamble signal is transmitted through the transceiver 220 and the antenna 500. In the ♯mi terminal device 100, the preamble signal is received by the antenna 130 in FIG. 3 and input to the spread demodulator through the transceiver 120.

As described in the case of calling, when the terminal device is idle, the spread demodulator 112 operates with the preamble code so that the synchronous demodulation can always be performed. Therefore, when the preamble signal is input, the control of the synchronization circuit 114 is performed. (FIG. 7, 701).

As soon as the downlink preamble signal is synchronously captured, the uplink preamble signal is transmitted from the spread modulator 111 through the transceiver 120 and the antenna 130 under the control of the controller 140 (702 in FIG. 7).

This upstream preamble signal is transmitted to the antenna 50 of FIG.
0, input to the spread demodulator 212 through the transceiver 220.

The spread demodulator 212 of the No.n modulation / demodulation device 210 is, as described above,
Since the preamble signal has already been set to be received from the @mi terminal device, the input preamble signal is immediately captured (FIG. 7, 715).

Upon completion of synchronization acquisition, the spread modulator 211 switches the preamble code to the PN code for communication while synchronizing with the ♯mi terminal device 100 (716 in FIG. 7). In response to this, the terminal device 100 also switches the code of the spread demodulator 112 from a preamble code to a PN code for communication (FIG. 7, 70).
3) Subsequently, the spreading code of the spreading modulator 111 is switched from the preamble code to the PN code for communication (FIG. 7, 704).

On the switching device side, the spreading code of the spreading demodulator 212 of the No. n modulation / demodulation device is switched from the preamble code to the PN code for communication while synchronizing with the terminal device side (FIG. 7, 717).
The setting of both the uplink and downlink radio channels between the n modem 210 and the ♯mi terminal device 100 is completed.

As described above, the synchronization acquisition by the preamble signal and the switching to the communication PN code are performed in the compeldo format. Therefore, by the code switching in FIG. Can be confirmed that the setting is completed.

Thereafter, the central control unit 240 controls to send a ringing tone to the calling party and to send a calling signal to the called party, as in the ordinary switching equipment (FIG. 7, 718). In transmitting the call signal, a command for controlling the call signal transmission is transmitted to the terminal device on the D channel in FIG.
Then, the control device 140 receives this and drives the ringer 166.

As described above, at the time of calling or receiving, between the terminal device 100 and the switching device 200 using the idle modem 210,
By setting a wireless channel by spread spectrum communication, a wireless communication system with n simultaneous calls / communications can be realized. In this system, since the equipment on the switching device side is independent of the number of terminal devices when the number of simultaneous calls / communications is within the range of n, it is economical in an application area where the traffic volume per terminal device is relatively small. is there.

In the above embodiment, the terminal device #m ₁ and ♯mi in the fourth diagram, a case has been described in which a call through the child changer 200 of the floor, through a main switching device 300, for example ♯1 and ♯l are the same even if the terminal device is a call / communication, also #m ₁ terminal and ♯nj terminal device, even if a call / communication through #m and ♯n child changer, different switching operation of the switching device is slightly Only the parts related to the present invention, such as the setting of a wireless channel between the terminal device and the modem device in the switching device, call detection, calling, etc., are the same.

Therefore, the switching method is not affected by distributed control, centralized control, the configuration of the time-division communication path, etc.
The present invention is applicable.

The signal transmission method between the switching device and the terminal device is not limited to the format of FIG.
B + B + D shown in FIG. 5 (b) may be used, or a completely different system may be used.

Further, in the embodiment, in the case of a telephone, a case is described in which a call is dialed by a dial 165, a call is made from a speaker by a tone ringer 166, and a call is made by a handset 163, 164.
1,112 and the PCM modems 161,162
It is also possible to perform data communication by switching to 70,
It goes without saying that the connection can be made by inputting the other party number / code using the keyboard in the data terminal device 170 instead of the dial 165.

Although the present embodiment has been described with respect to a telephone in the case of one time slot of 8 bits and 8000 frames / second, one digital radio channel is set between the terminal device and the switching device. Even if it is an exchange device, there is no problem in sending an image signal.

b. Second Embodiment In a second embodiment, as shown in FIG. 2, a switching apparatus transmits a synchronization signal based on a spread spectrum signal from a spread synchronization signal generation circuit 280, and connects a switching apparatus and a terminal apparatus to a spread spectrum communication channel. Are operated in synchronism with each other, thereby enabling use of time-division multiplexing of the spread spectrum modulation / demodulation device 210 on the switching device side.

The switching devices 200 and 300 are composed of 8000 frames per second as in the first embodiment, and are connected to the highways 260-1 to 260-2.
On 60-r and 261-1 to 261-r, one frame is composed of n time slots. These frames, time slots, etc. are stored in the synchronization signal generation circuit 27 shown in FIG.
Synchronization is achieved by a synchronization signal supplied from 0.

Each terminal device 100 is individually provided with a P for spread spectrum.
The N code, PNU (for up) and PND (for down) are given. The PN codes for the terminal device J (not shown in FIG. 4) are represented by PNUj and PNDj.

In the present embodiment, a PN code PNC for receiving a synchronization signal, which is common to all terminal devices operating with the same synchronization signal, is provided. This PNC also serves as a preamble code.

When the switching device, for example, 200 enters the operating state, the spread synchronizing signal generation circuit 280 of FIG. 2 receives the synchronizing signal from the synchronizing signal generating circuit 270, spreads the spectrum of the terminal synchronizing signal with the spreading code PNC, and transmits / receives. Machine 220, transmitting through antenna 500. FIG. 8 illustrates the spread synchronization signal transmitted.

FIG. 8 (a) shows the spread synchronization signal transmitted from the switching device on the time axis, and the PNC on the lower side of the horizontal axis in the figure is shown.
Indicates that the upper signals SNC _{1 to} SNC _{n on} the horizontal axis are spread-modulated by the spreading code PNC. Synchronizing signal SNC ₁ ~SNC _n corresponds to the time slot, the receiving side by receiving the I, can identify the time slot number. That is, it is also a frame synchronization signal.

Here, since the synchronization signal also serves as a preamble signal, the spread code PNC is required to be a simple code and a repetition of the same code in order to shorten the time until synchronization acquisition. , The length of the spreading code PNC is
It is preferably the time slot length or a fraction thereof.

b.1.Terminal device start-up operation On the terminal device side, when the power is turned on, the synchronization signal is received and the signal is synchronously captured. I do. This state will be described with reference to the flowcharts of FIGS. 3, 8, and 9.

In FIG. 8, since the power supply of the terminal device J is performed irrespective of the operation of the switching device, it is not synchronized at first.

When the power of the terminal device J is turned on (FIG. 8,
(B)), the control device 140 shown in FIG.
The operation is started by the control of 40 (FIG. 9, 901). First, the PN generator 113 generates a PN code PNC for receiving a spread synchronizing signal (902, FIG. 9), and the spread demodulator 112 starts demodulation operation with the PN code PNC (903, FIG. 9). On the other hand, the synchronization circuit 114
The PN generator 113 is controlled to start the synchronization acquisition operation (9th
(Fig. 911). When the power is turned on, the received signal and the spread demodulator 112
Since the PN code is not synchronized as shown in FIG. 8 (b), no output is obtained from the spread demodulator 112. However, when the PN code is synchronized with the received signal under the control of the synchronization circuit 114, the spread demodulator 1
An output is obtained from 12 (FIG. 9, 904), and the synchronization acquisition is completed (FIG. 9, 912).
The operation proceeds to the synchronous tracking operation (FIG. 9, 913).

The completion of the synchronization acquisition allows the time slot number of the switching device to be obtained from the received synchronization signal, whereby the synchronization signal such as the clock, time slot, and frame in the terminal device 100 is adjusted to the switching device. Thereafter, as shown in FIG. 8 (b), the synchronization shift is corrected by a synchronization signal received substantially every one frame.

The controller 140 informs the PN that the synchronization acquisition has been completed.
By controlling the generator 113, the PN code to the spread demodulator 112 is switched from the PNC to the down PN code PNDj given to the own terminal device (905 in FIG. 9), and the spread demodulator 112 demodulates with the PN code and PNDj. The operation is started (FIG. 9, 906). At this time, in the terminal device 100,
Since it is not known in which time slot switching apparatus 200/300 will call, the demodulation operation is performed with PNDj for all time slots as shown in FIG. 8 (b). To maintain synchronization, for example, as shown in FIG. 8 (b), the PN generator 113 is controlled to change the PN code of the spread demodulator 112 to PNC and receive a synchronization signal at every (n + 1) th time slot.

The control device 140 monitors the output of the spread demodulator 112, and if no signal is detected, continues the demodulation operation in the next time slot (907 in FIG. 9). To identify the incoming call,
The operation of the spread demodulator 112 is fixed to the time slot,
The demodulation operation in other time slots is stopped to prevent malfunction (908 in FIG. 9). The reception of the synchronization signal is also fixed to a time slot immediately before the time slot, for example, as described later, in order to simplify the control.

Of the above operations, the operation when the determination in 907 in FIG. 9 is NO is the operation when the terminal device is idle.

b.2. Transmission operation Next, the operation when the terminal device transmits a signal will be described with reference to the time relationship diagrams of FIGS. 2, 3, and 10, and the flowchart of FIG.

When the caller raises the handset of the terminal device J, the control device 140 shown in FIG.
(1101, FIG. 11), generates an uplink PN code (PNUj) from the PN generator 113 via the interface circuit 150, and generates a calling signal by the spreading modulator 111 using the PN code using all time slots. The code is spread-modulated, and the
0, transmit through antenna 130 (FIG. 11, 1102). The signal spread and modulated here is, for example, as shown in FIG.
It is a signal having a configuration such as B + D or B + B + D. Here, the description will be made assuming a B + D format. That is, TS ₁ , TS _2, etc. in the upper part of the horizontal axis in FIG. 10 (α) represent time slot numbers, the hatched portion represents the D signal, and the unhatched portion represents the B signal. FIGS. 10 (a), (b), (e),
The frames in (f) does not begin from the TS ₁ is because they relate to the highway interchange device.

The calling signal can be a specific pattern of signals,
Calling conditions (telephone, data, etc.) shall be sent and determined by the system. Regarding the time relationship, the transmission is performed in synchronization with the switching device based on the synchronization signals SNC〜 sent from the switching device shown in FIG. 8 (b) and FIG. 10 (f).

In the switching devices 200/300, the central control device 2 shown in FIG.
Reference numeral 40 designates each modem 210 (or at least one of the modems if a plurality of modems are provided in the same service area) by using an empty time slot to transmit the upstream PN signal (PNU to ) To sequentially drive the spread demodulator and scan all available terminal devices for calls (1111 in FIG. 11).

Now, FIG. 10B will be described. Assuming that the corresponding modem unit 210 on the switching device side is the No. 1 device, the central control unit 240 detects the outgoing call of the terminal device m in the time slot 1 (on the highway) of the frame q. The uplink PN code PNUm of the terminal device m is generated by the PN generator 213 to drive the spread demodulator 212, but no signal is obtained, indicating that no call is detected. The subsequent time slot 2 (on the highway) has already been used for communication with the terminal device i.

In time slot 3 (on the highway) of frame q, a spread demodulator 212 with a PN code PNUj under the same control as in time slot 1 to detect a call from terminal device J.
Is driven (FIG. 11, 1112). In the terminal device J, as shown in FIG. 10 (a), since the calling signal has already been spread-modulated with the PN code PNUj and transmitted, the calling signal is demodulated by the spread demodulator 212 and Detected by device 217. Then, the notification is sent to the central control device 240 via the signal reception / distribution device 230 (FIG. 11, 1113). The central control unit 240 includes the spread demodulator 2
Since 12 detects the calling signal with the PN code PMUj, it identifies that the terminal device J has issued it (FIG. 11, 1114).

The central control unit 240 selects an upstream (highway transmission) time slot and a downstream (highway reception) time slot for a dial tone connection (transmission of a dial tone or connection to a push button signal receiver, etc.). At this time, the uplink time slot may be a time slot used for call detection or a different time slot (FIG. 11, 1115). Subsequently, in the selected downlink time slot, for example, TSn (time slot 1 on the highway), the No. 1 modem
The control unit 217 is instructed via the signal receiving and distributing device 230 to operate the spread modulator 211 of 210 with the PN code PNDj, and the uplink time slot is set to, for example, TS2 (time slot 3 on the highway). Is assigned to

The control device 217 controls the PN generator 213 and the spread modulator 211
Operates with the PN code PNDj in time slot TSn, spread demodulator 212 is set as to operate in the PN code PNUj in time slot TS ₂ (FIG. 11, 1116). At the same time via the buffer memory 215, and input to the spread modulator 211 and the uplink time slot number TS ₂ as a signal, and transmits to the terminal device J (Fig. 10 (e), FIG. 11, 1117).

At this point, the modem 210 and the highways 260 to
It is not necessary to connect / 261 ~. Further, in a system in which the uplink time slot changes from the time slot used for call detection, after transmitting the uplink time slot number to the terminal device, the switching device synchronizes with the spread modulator 111 of the terminal device, and It is preferable to switch the time slot on the side. The synchronization circuit 214 shown in FIG.
Synchronous tracking of

In the terminal device J, as shown in FIG. 8 (b) and FIG. 10 (f), the spread demodulator 112 (FIG. 3) operates with the PN code PNDj in all the time slots. receives the uplink time slot number TS ₂ in TSn (FIG. 11, 1103), confirms that the calling detection that this was performed in the exchange device 200/300, the controller 14
0 controls the PN generator 113 to make the operation of the spread modulator 111 TS ₂
, And the operation of the spread demodulator 112 is fixed to TSn (FIGS. 10 (a) and (f), FIG. 11, 1104).

It is assumed that the terminal device 100 receives the synchronization signal at every (n + 1) th time slot so that the signal can be detected with a delay of at most one frame, regardless of which time slot is received (FIG. 8, (b)). After the communication time slot is fixed, the time slot for receiving the synchronization signal is also fixed. This is because if the synchronization signal is continuously received every n + 1 time slot, the synchronization signal is received once every n frames in the communication time slot. In the example of FIG. The synchronization signal was received in the previous time slot.

On the switching device side, after transmitting the uplink time slot number to the terminal device 100, (a signal for confirming that the uplink time slot number has been received from the terminal device 100 may be transmitted and may be received). For example, a push button signal receiver (not shown) is selectively captured, a channel is set to a time slot on the highway that has already been selected for the calling terminal, and a second time slot number on the highway is used. By operating the buffer memories 215 and 216 in the figure, the No. 1 modem 210 and the highway 260-1 and
261-1 is connected (FIG. 11, 1118).

When a dial tone is transmitted from the push button signal receiver and dialing is performed with the terminal device, a multi-frequency signal corresponding to the dial is transmitted to the push button signal receiver.

The details of the multi-frequency signal transmission operation in the terminal device 100 will not be described, but the PCM-encoded multi-frequency signal corresponding to the dial signal received by the control device 140 is
This is performed by sequentially inputting the signals to the spread modulator 111.

With the above operation, the wireless channel between the terminal device 100 and the switching device 200/300 has been set.
The operation of 0 is performed in the same manner as a known operation.

In the above description, for example, in FIG. 10, when the uplink time slot number is transmitted from the switching device to the terminal device, it is written to be transmitted within one frame.
Obviously, transmission over a plurality of frames does not cause any problem, and is not limited to the drawing. Although the description is omitted, the addition of the D channel is shown in FIG.
The processing is performed in the buffer memories 215 and 216 in the same manner as in the first embodiment.

b.3. Incoming call operation The time relationship diagrams in FIG. 2, FIG. 3, and FIG.
The operation in the case of an incoming call will be described with reference to the flowchart of FIG.

In FIG. 2, when the central control unit 240 receives the called number (1311 in FIG. 13), it immediately identifies that the called terminal device is, for example, “J” from the called number (FIG. 131, 131).
2).

Subsequently, the central control unit 240 selects a modem 210 capable of calling the called terminal device J. If there is only one modem 210 that can call the terminal device J, it is uniquely determined, but if there are multiple modems 210, a modem with an empty channel between the calling terminal and the incoming line is selected ( (Fig. 13, 1313).

At the same time, the transmitting and receiving highways 260-r and 261-r transmit an empty time slot between the calling terminal device or the incoming line and the selected modem 210, for example, the No.n device.
Select above. In the present embodiment, since the time slot of the highway and the time slot of the radio channel correspond to each other, both the upstream and downstream time slots between the No.n modem 210 and the called terminal device J are selected. (Fig. 13, 1314). Thisゝa, TSn as uplink time slot, and TS ₂ is selected as the downlink time slots (Figure 12).

By the above, the modem 210, the terminal device 100, the uplink,
Downlink time slots, each No.n, No.J, TSn, TS ₂
Since fixed and central controller 240 gives instructions to the control unit 217 of No.n modem 210 via the signal receiving distributor 230, the spread modulator 211 under the control of the control unit 217 in the time slot TS ₂ The spread demodulator 212 is set to perform the spread modulation operation with the PN code PNDj (FIG. 13, 1315), and the spread demodulator 212 is set to perform the spread demodulation operation with the PN code PNUj in the time slot TSn (FIG. 13, 1316).

Further, the control unit 217, the downlink buffer memory 215 in time slot TS _2, enter the necessary information as the incoming signal, the uplink time slot number TSn to be used,
The spread modulator 211 performs spread modulation with PNDj and transmits the spread modulated signal through the transceiver 220 and the antenna 500 (FIGS. 12, (b) and 13).
(Fig. 1317).

In No. J terminal apparatus 100, this signal is received by antenna 130, amplified by transceiver 120, and input to spread demodulator 112. In the No. J terminal device, as shown in FIG.
Since the continuous spread demodulator 112 performs the spread demodulation operation in all time slots with the PN code PNDj, the transmitter / receiver
The signal input from 120 is immediately demodulated, the incoming signal,
The uplink time slot number TSn is detected as a signal (FIG. 12, (c), FIG. 13, 1301).

In the terminal device 100, the control device 140 is an interface circuit.
Receive this through 150, process the incoming call, and
The operation of the spread demodulator 112 is fixed to the time slot TS ₂ by controlling the generator 113, while fixing the received synchronization signals to the previous time slot. That position of the time slot TS ₁ is demodulated operating in PN code PNC, the to receive the synchronizing signal SNC ₂ (Figure 12, (c), FIG. 13 1303).

Similarly, the PN generator 113 is controlled so that the spreading modulator 111 operates in the received time slot TSn (FIGS. 12, (d), and 1302 in FIG. 13). The control device 140 inputs a confirmation signal for confirming that the incoming signal has been received to the spread modulator 111, and transmits the signal to the switching devices 200/300 through the transceiver 120 and the antenna 130 (FIG. 13, 1304).

By the above operation, switching devices 200/300 and terminal device 100
Since the channel between them has been set, the control device 140 causes the ringer 166 to sound via the interface circuit 150 and sends out a calling signal (FIG. 13, 1305).

On the other hand, on the switching device side, the spreading demodulator 212 of the No. n modulation / demodulation device 210 already has a PN code in the time slot TSn.
Since the terminal operates on PNUj, the confirmation signal sent from the terminal device 100 is immediately demodulated (FIG. 13, 1318), and is sent from the control device 217 to the central control device 240 via the signal reception / distribution device 230.
Is forwarded to Central control device 240 confirms the channel setting with the terminal device, and performs incoming connection processing such as ringing tone transmission (FIG. 13, 1319).

As described above, according to the present invention, it is possible to make wireless between the switching device and the terminal device.

Incidentally, the Fig. 12 (b), will be described for the state of reference of (e), first (b) in the time slot TSn terminal device K, the time slot TS ₁ is used in the terminal apparatus I, time slot TS ₂ indicates that began to be used from the frame q to the terminal device J.

FIG. 12 (e) shows a time slot TSn of frame q.
(TS _{1 on the} highway), the call detection of the terminal device M was performed, but no call was indicated, indicating that the time slot TSn was used by the terminal device J from frame q + 1. I have. Therefore, the subsequent call detection is performed by using another empty time slot.
The time slot TS ₁ the terminal K, the time slot TS ₂ indicates that it is used in the terminal apparatus I.

Although the second embodiment has been briefly described above, it is clear that the operation is the same as that of a digital switching system having a time slot memory in a terminal device after a wireless line is set up. All the functions of the communication system can be introduced.

In the present embodiment, an example has been described in which the highway of the switching device is extended as it is to the wireless channel between the switching device and the terminal device. However, the buffer memories 215 and 216 in FIG. If a function is provided, the allocation of time slots on the wireless channel can be determined completely independently of the highway of the switching device, and the number of time slots, that is, the transmission speed can be made independent. For example, the time slot of the wireless channel may be tied to each terminal device, and a configuration such as concentrating at the point where the buffer memories 215 and 216 are connected to the highway is also possible.

In the embodiment of FIG. 2, as shown in FIG. 4, both the main switching device and the child switching device have a switching function, in other words, the connection between the terminal devices accommodated in the same child switching device. Is
In this case, the buffer memories 215 and 216 in FIG. 2 are provided with a time switch function, and the highways 260-1 to 260-r and 261-1 to 261-r are connected to the cable 600 ( For example, a high-speed digital highway using an optical fiber) is replaced by the central control unit 240 provided in the main switching unit and the control unit 21 in the modem unit 210.
If the communication with 7 is configured so that a part of the time slot on the highway is used as a signal channel, the child switching device of FIG. At this time, all communication between terminal devices in the same modem is also performed via the main switching device via the node device 610 and the cable 660. In other words, the modem 21
It is also possible to configure a switching system using 0 as a remote concentrator.

In the above-described embodiment, the ISDN based on 64 kb / s voice has been described. However, for example, if the time slot is increased, the present invention can be used for message slot type packet communication.

Further, in the switching system of the present invention, since the access channel from the terminal device to the switching device is individually provided by the terminal device, it is functionally equivalent to having a star-shaped wiring. If the terminal device receives a communication start permission signal from the switching device and starts communication, for example, after transmitting a call signal, and performs, for example, packet transmission, the terminal device is connected to a star-type local area network (LAN). The same function can be realized.

By taking advantage of noise immunity, one of the features of spread-spectrum modulation, it is possible to perform superior line transmission using an existing local cable for voice communication with a large amount of attenuation in the high-frequency region.
It can also be used as a subscriber line transmission system in ISDN.

In the method of spread-spectrum modulation of a time-division multiplexed signal as shown in the second embodiment, a twisted pair or a wired transmission line such as a coaxial cable is used as a transmission line between a terminal device and a switching device. By connecting a plurality of terminal devices on the same cable, so-called articulated type or multi-drop type, it is possible to provide communication between a plurality of terminal devices and one switching device with one cable without using spatial electromagnetic waves. Also becomes possible.

This method is very useful when using a cable installed along the railway, road, or power line, since a single cable can provide multiple independent communication paths to many terminals with a single cable. It is economical.

〔The invention's effect〕

The present invention provides a highly confidential and highly noise-resistant wireless communication system, a multiplexed communication system for terminal lines,
Alternatively, providing a high-speed digital transmission system using a low-frequency line, if a wireless system is applied to the office, individual indoor wiring to the terminal device becomes unnecessary, so installation work is extremely easy, and rearrangement in the office is possible. In addition, even when the terminal device is moved, an extremely flexible communication system that does not require any wiring work can be constructed. In particular, in applications in offices, since weak radio waves can be used, there is no problem in radio wave management, and there is an effect that the system can be made wireless.

Furthermore, if applied to local communications, for example, by laying leaky coaxial cables or telephone cables or coaxial cables along roads, it is not necessary to lay cables at all in individual subscribers' homes. There is an effect that individual simultaneous communication can be performed only by the drop-in wiring from the trunk line.

Furthermore, using the subscriber cable of the existing subscriber telephone network,
Since high-speed digital transmission can be performed, even when an existing telephone network is migrated to ISDN, there is an effect that the line equipment can be used as it is.

By combining the present invention with mobile communication technology, it is also possible to integrate a system which is currently divided into a general subscriber telephone and a car telephone, so that an individual always carries his / her own telephone or terminal device, and This has the effect of enabling a future communication system capable of performing communication regardless of the communication system.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 and FIG. 2 are system configuration diagrams on the exchange side showing first and second embodiments of the present invention, and FIG. System configuration diagram showing an embodiment, fourth
FIG. 5 is a block diagram of a distributed switching system showing an example in which the present invention is applied to an office building. FIG. 5 is a diagram showing signals on a highway and wireless communication to a terminal device in the first embodiment of FIG. FIG. 6 is a time relationship diagram showing a relationship between signals on a transmission line.
FIG. 7 is a flowchart showing an outline of a calling operation in the first embodiment, FIG. 7 is a flowchart showing an outline of an incoming call operation in the first embodiment, and FIG. 8 is a flowchart in the second embodiment of FIG. FIG. 9 is a time relationship diagram showing the state of the signal of the demodulation operation from the synchronization signal and the terminal device being turned on to the acquisition of the synchronization and waiting for the incoming call. FIG. 9 shows the second embodiment. Is a flowchart showing an outline of the operation up to the end of the period, FIG. 10 is a time relationship diagram showing a mutual relationship between signals at the time of calling operation in the second embodiment, and FIG. 11 is a time relationship diagram in the second embodiment. A flowchart outlining the calling operation;
FIG. 12 is a time relationship diagram showing a mutual relationship between signals at the time of an incoming call operation in the second embodiment, and FIG. 13 is a flowchart showing an outline of an incoming call operation in the second embodiment. 100 terminal device, 111 spread modulator, 112 spread demodulator, 113 PN generator (pseudo noise code generator), 114
... Synchronous circuit, 120 ... Transceiver, 130 ... Antenna, 140
…… Control device, 150 …… Interface circuit, 161 …… PC
M modulator, 162 ... PCM demodulator, 163 ... Transmitter, 164 ...
Handset, 165 …… Dial, 166 …… Ringer, 170 ……
Data terminal device, 200: switching device (child), 210: modulation / demodulation device, 211: spreading modulator, 212: spreading demodulator, 213
…………………………………………………………………………… PN generator (pseudo noise code generator), 214 ……………… Synchronization circuit, 215,216 …… buffer memory, 215-1,216-1 ……
Time slot switch, 215-2,216-2 time slot memory, 215-3,215-4,216-3,216-4 shift register, 217 control device, 220 transceiver 230
…… Signal reception and distribution device, 240 …… Central control device, 250 ……
Switching network, 260-1, ..., 260-r ... receiving highway, 261-1, ~ 261-r ... transmitting highway,
300 ... Exchange device (main), 400 ... External cable, 500 ...
... antenna, 600 ... cable, 610 ... node device.

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Tadahiko Akiyama 94-Senba, Koriyama-shi Nippon Tsushin Kogyo Co., Ltd. (56) References JP-A-59-49033 (JP, A) JP, B2)

Claims (1)

(57) [Claims] 1. A communication apparatus comprising: a plurality of terminal devices; and a switching device for switching connection of the plurality of terminal devices.
The terminal device includes a first transceiver used for transmitting and receiving signals to and from the switching device, and a first spread-spectrum modulator / demodulator that performs spread-spectrum modulation / demodulation of the signal with a spreading code unique to the terminal device. A switching device for controlling switching connection of the terminal device, a second transceiver for transmitting and receiving the signal to and from the terminal device, and switching means for switching and connecting a call of the terminal device under the control of the control device; A second spread-spectrum modulator / demodulator connected to the second transceiver and the switching means for connecting the plurality of terminal devices to the switching device and performing spread-spectrum modulation and demodulation based on a spread code selected by the control device; Receiving a call to the terminal device, when the control device of the switching device identifies the called terminal device, the plurality of second spread spectrum modulation Selects the second spread-spectrum modem empty state of the vessel, the second said selected empty
The synchronization spread code corresponding to the called terminal device is selectively set in the spread spectrum modulator / demodulator, and a signal modulated by the synchronization spread code is transmitted to the called terminal device to obtain synchronization. A different spreading code is set for the called terminal device different from the called terminal device, and the switching means performs a connection process between the selected empty second spread spectrum modulator / demodulator and the call destination, from the terminal device. The control device of the switching device transmits, to the empty second spread-spectrum modem among the plurality of second spread-spectrum modulators / demodulators, individual synchronization signals corresponding to each of the plurality of terminal devices. Spreading codes are sequentially selected and set in a time-division manner, and if any of the empty second spread-spectrum modulators and demodulators identifies the calling terminal device by the selected and set synchronization spreading code, it is considered that a call is detected. Then, an individual communication spreading code corresponding to the calling terminal device is set in the second spread spectrum modulator / demodulator that has detected the call, and the switching means includes a second spread spectrum modem that detects the call. A communication device for performing a connection process with a called party.