JPH0129104B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a telephone switching system, and particularly to a telephone switching system interlinked by wireless lines for use in depopulated areas.

As this type of exchange system, the one shown in FIG. 1 is known. An analog space division radio telephone exchange RSS for depopulated areas is connected between the master telephone exchange EX and the base station radio telephone exchange BASE/STN. This wireless telephone switching system for depopulated areas uses subscriber telephones housed in the master telephone exchange
It is installed when SUB ₀ ~ SUB _o is located far away or it is difficult to install a wired cable, and the subscriber telephone SUB ₀ ~ SUB _o
A communication path is established wirelessly between the two.

This radio transmission and reception is carried out between the terminal radio equipment SUB SET ₀ to SUB SET _o on the subscriber phone side and the base station radio telephone exchange installed on the EX side of the master telephone exchange side.
BASESTN and radio channel RFCH ₀ ~
For RFCH _n , a channel corresponding to the amount of traffic corresponding to the number of subscriber telephones SUB ₀ to SUB _o is prepared. The radio channels RFCH ₀ to RFCH _n (where m<n) are the same as the installed number of trunk units TCU ₀ to TCU _n , which are outgoing devices of the radio telephone exchange RSS for depopulated areas. Moreover, this wireless channel
RFCH ₀ to RFCH _n require an expensive transmitter TX and receiver RX for each channel. Since the base station wireless telephone exchange BASE/STN is one station, it is only necessary to provide the transmitting section TX and receiving section RX for each channel, but the terminal radio equipment SUBSET ₀
~SUBSET _o must also be provided for each set depending on the number of channels, making the conventional system extremely expensive.

Furthermore, since the conventional system is an analog wireless system, it has the disadvantage that it is easily intercepted by a third party. If a frequency inversion method or the like is used to prevent this, it will be necessary to add a secret device, making the system complicated and expensive.

The present invention improves this point, and by time-division multiplexing digital signals to perform wireless communication to subscriber telephones, the number of wireless channels can be reduced to one, and the system can be configured at low cost. The purpose of the present invention is to provide a wireless telephone switching system for depopulated areas, which can improve the confidentiality of telephone calls.

The feature of the present invention is that the subscriber lines connected from the main telephone exchange are converged as in the conventional method, and at the converged point, analog signals are converted to digital signals and multiplexed into one digital channel. . By locating the analog-to-digital conversion point, that is, the codec, at a focused point rather than corresponding to the subscriber line, the total cost of the relatively expensive codec system can be reduced. When a codec is installed to support subscriber lines, a considerable amount of hardware is required at the front stage of the codec, that is, the interface with the main telephone exchange side (ringing detection and tripping at the time of incoming calls, loop closure at the time of outgoing calls, and dial relay). , call monitoring, etc.), which increases the hardware cost of the entire system. However, by placing the codec in a centralized location, the interface circuit can also be located in a centralized location, thereby reducing the hardware cost.

An embodiment of the present invention will be described based on the drawings.
FIG. 2 is a block diagram of essential parts of an embodiment of the present invention. The master telephone exchange EX has subscriber circuit units LCU ₀ to 1 in the radio telephone exchange RSS for depopulated areas.
LCU _o is connected. The subscriber circuit units LCU ₀ to LCU _o are converged to a space division switch SW and connected to trunk units TCU ₀ to TCU _n (m<n). This trunk unit TCU ₀ ~
TCU _n has codecs CODEC ₀ to 0 to perform analog-to-digital conversion or digital-to-analog conversion.
CODEC _n is connected one to one. This codec CODEC ₀ ~ CODEC _n is a digital switch.
Connected to DSW. This digital switch
A transmitting section TX and a receiving section RX provided corresponding to one radio channel in the base station wireless telephone exchange BASESTN are connected to the DSW. An antenna is connected to the transmitting section TX and receiving section RX. Further, a control device CONT is connected to the space division switch SW. moreover,
The output of the control device CONT is the digital switch
It is connected to the DSW and the base station wireless telephone exchange BASESTN, and controls the time slot of time division multiplexing and the timing of transmission and reception.

Further, in FIG. 2, SUB ₀ to _{SUB o} are subscriber telephones accommodated in the master telephone exchange EX. This subscriber telephone SUB ₀ ~ SUB _o has a codec
CODEC′ ₀ to CODEC′ _o are connected to each other.
Terminal wireless devices SUBSET ₀ -SUBSET _o are connected to the codecs CODEC' ₀ -CODEC' _o , respectively.

With this kind of circuit configuration, subscriber telephones in depopulated areas can
When the subscriber circuit units LCU ₀ to LCU _o provided corresponding to SUB ₀ to SUB _o detect a call signal supplied from the master telephone exchange EX when a call is received from the master telephone exchange EX, they control it. FEED TO THE DEVICE CONT. As a result, the control device CONT selects an empty trunk unit from among the trunk units TCU ₀ to _{TCU n} corresponding to the number of channels prepared according to the traffic, and connects it to the subscriber circuit unit LCU _i that received the call. Close the space division switch SW between trunk TCU _j and connect. trunk unit
The output of TCU _j is digitized by the codec and sent to the digital switch DSW. Here, call signals etc. to other subscriber telephones are time-division multiplexed into one channel and sent to the base station wireless telephone exchange BASESTN. The base station wireless telephone exchange BASESTN transmits this digital signal from the transmitter TX of the wireless channel RFCH to the subscriber telephone SUB _0.
~ Send to SUB _o .

The terminal wireless device SUBSET _i extracts a digital signal corresponding to its own time allocation from this multiplexed digital signal and uses it as a codec.
CODEC′ _i converts this into an analog signal and outputs it to subscriber telephone SUB _i to set up a communication path.

Additionally, calls are bidirectional and the subscriber phone SUB ₀
~The call signal from SUB _o to the master telephone exchange EX is
This is performed via the downlink multiplexed digital channel and another uplink multiplexed digital channel. That is, it is performed via the reception unit RX of the radio channel RFCH of the base station radio telephone exchange BASESTN.

In addition, if the calling operation is indicated, the subscriber telephone
SUB ₀ ~ SUB _o caller (e.g. subscriber telephone
When SUB _i ) picks up the handset, the terminal radio device SUBSET _i senses this and identifies the caller via the uplink multiplex channel, that is, the receiver RX of the base station radio telephone exchange BASESTN. Control device for radio telephone exchange RSS number for depopulated areas
Sent to CONT. The control device CONT selects an empty trunk unit, for example, TCU _L , and connects it to the subscriber circuit unit LCU _i corresponding to the subscriber telephone SUB _i of the previously received caller identification number using the space division switch SW to make a call. form a road.

With the communication path formed, the subscriber circuit unit LCU _i creates a loop to activate the master telephone exchange EX. The master telephone exchange EX then connects the calling register and enters the call number receiving state. In this state, when the called subscriber number is dialed from the subscriber telephone SUB _i , the dial information is multiplexed into the corresponding time slot of the uplink channel and sent to the base station wireless telephone exchange. This dial information is received by the receiving section RX, given to the control device CONT via the trunk unit _TCUL , and relayed to the originating register of the master telephone exchange EX via the loop circuit. The master telephone exchange EX connects the called party's subscriber telephone based on this dial information, and when the called party answers, the call status is established. Call operations are performed via uplink and downlink radio channels as described above.

As explained above, according to the present invention, subscriber lines from a master telephone exchange are converged into a trunk unit via a space division type switch, and a codec is installed in this trunk unit on a one-to-one basis to perform analog-to-digital conversion. We decided to time-division multiplex digital signals and put them on a single radio channel to connect subscriber telephones and exchanges in depopulated areas.

Therefore, the interface circuit with the master telephone exchange, such as ringing detection at the time of incoming call, activation by tripping or loop formation at the time of outgoing call, loop interruption for dialing information relay, and destination response monitoring, etc., is integrated into the trunk. It can be installed in the unit. Furthermore, there is no need to provide a codec for each subscriber telephone, so the number of codecs can be reduced, and the system can be constructed at low cost.

Furthermore, one radio channel can be used, and the cost can be reduced by providing one base station radio telephone exchange and one transmitting section and one receiving section of the terminal radio device.

Furthermore, since it is a digital multiplex radio system, it has the advantage of improving the confidentiality of telephone calls.

[Brief explanation of drawings]

FIG. 1 is a block diagram of the main parts of a conventional device. FIG. 2 is a block diagram of essential parts of an embodiment of the present invention.

Claims (1)

[Claims] 1. A radio for depopulated areas, comprising a base station and one or more subscribers connected to the base station via a wireless line, and providing an interface to the base station to a master telephone exchange EX. Telephone exchange RSS and
A base station wireless telephone exchange BASE STN is provided, which is connected to the wireless telephone exchange for depopulated areas and includes a transmitting section and a receiving section and transmits and receives wireless signals. In a wireless telephone exchange system for depopulated areas including subscriber telephones that transmit and receive radio signals between the two, a space division switch SW converges subscriber lines from the master telephone exchange to the wireless telephone exchange for depopulated areas. A codec CODEC is connected to the above-mentioned subscriber side of this space division switch via a trunk unit and performs mutual exchange of analog and digital signals, and a time clock corresponding to each subscriber telephone is connected to the digital side of this codec. The base station wireless telephone exchange is equipped with a digital switch DSW that multiplexes and separates the digital signals of each codec, and the base station wireless telephone exchange has one wireless transmitter (TX) and one receiver RX connected to the multiplex side of the digital switch. A telephone exchange system for depopulated areas that is characterized by: