JPS5958927A - Digital mobile radio exchange system - Google Patents

Abstract

PURPOSE:To attain the communication between one or plural mobile terminals and a subscriber terminal and that between the mobile terminals in the efficient way, by providing an assigning means assigning a prescribed time slot to the subscriber terminal and the mobile terminal moving along a transmission line. CONSTITUTION:When a call request exists respectively between terminals #1 and #11 and between a terminal #2 and a mobile terminal #17, the time slot information on an incoming highway 57a is written sequentially in a storage memory 18 of exchange 5', and the time slot assignment on an outgoing highway 57b is transmitted as the channel assignment when the information is read out on an outgoing highway 57b. Thus, a voice communication current at the terminal #11 reaches the terminal #1, the current of the mobile terminal #17b reaches the terminal #2, the current at the terminal #1 reaches the terminal #11 and the current at the terminal #2 reaches the mobile terminal #17, allowing to make communication mutually.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a digital mobile radio telephone system for telephone exchange of mobile terminals mounted on tracks, vehicles, automobiles, etc. that move along access lines accommodated in a time division exchange. be.

In conventional space-division telephone exchanges, the communication band uses the voice frequency band, so there are various technical and economic constraints on the subscriber line length and trunk line length that can be accommodated in this exchange. Therefore, when these lines become long distances, multiplex transmission lines are used, or the switching center is divided and the lines are accommodated in each switching center. That is, as shown in FIG. 1, subscriber terminal groups 1, 2.3 consisting of a large number of subscriber telephones are housed in exchanges 4, 5.6 installed in areas A, B, and C, respectively. 4 and 5
The multiplex transmission devices 11 and 12 are connected to each other by a multiplex transmission path 7, and the exchanges 5 and 6 are connected to the respective multiplex transmission devices 13 and 14 by a multiplex transmission path 8.
The multiplex transmission equipment 15 and the multiplex transmission equipment (not shown) are connected to the exchanges in other areas (not shown) through multiplex transmission lines 9, and the exchange 6 and the exchanges in other areas (not shown) are connected to each other by multiplex transmission lines 9. A multiplex transmission device 16 and a multiplex transmission device (not shown) are connected to each exchange via a multiplex transmission path 10, thereby configuring a switching network using long-distance lines. On the other hand, for a switching network with a small traffic volume, as shown in FIG. user terminal group 1, 3
This creates an economically advantageous exchange network.

Telephone switching networks for railways and highways require long-distance lines, so they are generally constructed using the switching network shown in FIG.
If the user moves on the road and enters another area during a call, it is necessary to perform a so-called tracking exchange, which makes the exchange control complicated. or,
Multiple terminals have drawbacks such as the need to allocate a radio frequency to each terminal.

Therefore, the present invention provides a digital mobile radio switching system that uses a digital switching network to eliminate the above-mentioned drawbacks of the conventional technology. It is possible to effectively carry out calls between one or more mobile terminals and subscriber terminals, and between said mobile terminals, and to achieve this purpose, some or all of the digital exchanges are installed. Subscriber terminals accommodated in each of a plurality of repeaters inserted at predetermined intervals in a transmission path connecting an outgoing highway and an incoming highway, and mobile terminals moving along the transmission path. having an allocation means for allocating a predetermined time slot to the
The present invention is characterized by further comprising a notification means for notifying the plurality of repeaters of this time slot information, and a setting means for arbitrarily setting a time slot used for communication with the mobile terminal.

Hereinafter, the present invention will be explained in detail with reference to the drawings. FIG. 3 shows an embodiment for explaining the configuration of the digital mobile radio switching system according to the present invention. In the figure, the same parts as in FIGS. 1 and 2 are given the same reference numerals, and detailed explanations are omitted. 5' is a digital exchange, and 18 and 21 are digital exchanges 5.
51 to 58 are the ingress and egress highways of the digital switch 5', 51a to 58a are the ingress highways, 51b to 58b are the egress highways, 71.8
1 is a line interface section, 71a and 71b are interface circuits on the transmitting side and receiving side of the line interface section 71, #1. #2 and #30 are subscriber terminals (telephones) accommodated in each of repeaters 701, 702,730 arranged in cascade along the road.

Now, the telephone exchange operation will be explained assuming that the Dintal exchange 5' is installed in area 8 in FIG. 1.

Each terminal in the subscriber terminal group 2 within the 8 areas is a subscriber circuit/! T
2i, and these subscriber circuits perform call origination and response for each terminal, processing of various signals, and encoding and decoding of voice communication current. Further, communication with other areas such as area C is carried out via the line interface section 81 and the multiplex transmission line 8. In area A, the above-mentioned subscriber terminals #l, #2...#30 are distributed along the road,
Assuming that mobile terminal #17 is also included, the call connection operation of mobile terminal #17 will be described below.

The bit rate of the ingress/egress highway 57 of the exchange 5' is 2.048 Mb/S for the PCMI next group, its frame structure is shown in FIG. It shall be. Furthermore, for ease of explanation, the channel numbers and subscriber terminal numbers in the frame structure shown in FIG. 4 are made to match. In other words, channel number #1 is the terminal accommodated in repeater 701.
'l VC% Channel number 1 #2 is made to match terminal #2 accommodated in repeater 702, respectively. Similarly, channel number #30 is made to match terminal ##30K accommodated in repeater 730. However, mobile terminal 1
It is assumed that the repeater 717 corresponding to 117 does not accommodate any other terminal. Therefore, the time slots on the input highway 57a have the channel assignments shown in FIG.

In this state, if a call request is made between the terminal 11 and the terminal #111 and between the mobile terminal and the mobile terminal #17, the time slot information of the incoming station 57aJ2 will be ' is written in the holding memory 18 of 7-ken/yal, and when it is read out onto the outgoing highway 57b, the time slot assignment on the outgoing highway 57b is set to the third
This is transmitted as the channel assignment shown in the figure.

As a result, the voice communication current of terminal #11 is terminal #'1v
The voice communication current of C1 mobile terminal #17 reaches terminal 412, the voice communication current of terminal #l reaches terminal #11, the voice communication current of terminal 2 reaches mobile terminal #117,
A mutual conversation takes place. Incidentally, calls to subscriber terminals in different areas of Iway, for example eight areas, are conducted in the same manner.

For a call with the mobile FHI terminal #17, the PCM signal on the outgoing highway 57b that accommodates the mobile terminal #117 is transmitted from the transmitting side interface circuit 71a to the multiplex transmission line 7, and as shown in FIG. The PCM frame configuration pattern shown in FIG.
A wireless signal f1 having the same PCM pattern is transmitted to each of the terminals 7 and 7.

Mobile terminal #-17 receives the time slot number O, which is a predetermined bit of the time slot registered in advance at the time of departure.
If there is incoming information on the predetermined individual signal f,
2 to respond.

A repeater, such as a repeater, that receives this response signal reaches the input highway 57a. From this V, exchange 5' learns that mobile terminal #17 has responded and performs a connection operation,
The mobile terminal 117 determines which call is being made. That is, the voice communication current of the other subscriber is written in the time slot registered on the output highway 57b of the exchange 5', and the voice communication current of each repeater 70 is written.
1.702730 at frequency f1, mobile terminal #f17 receives this, writes its own voice communication signal in the same time slot, and transmits it at frequency f2.

This frequency f2 is transmitted to the repeater 711 near mobile terminal #17.
receives the signal, and rewrites the corresponding time slot of the pattern on the incoming highway 57a side to the PCM voice communication signal of mobile terminal #17. As a result, the voice signal of mobile terminal #17 reaches the other party's terminal via exchange 5', and a mutual conversation is performed.

The exchange 5' monitors the group of individual signal bits in time slot No. 0, and when it detects that the individual signal bits have changed due to on-hook of any terminal, it ends the exchange operation.

Fig. 5 shows repeaters 701, 702, . . . 7 shown in Fig. 3.
In this example, it is assumed that a telephone terminal #11 housed in a repeater 711 and a mobile terminal #17 in the vicinity thereof are in communication.

In FIG. 5, parts corresponding to those in FIG.
and 19b are the transmitter and KOG of the transmitting unit 19, 20 is the receiving unit of subscriber terminal #11, and 20a and 20b are the receiving unit 2.
0 receiver and decoder, 21° 22 a PCM receiving circuit of the repeater 711, 23 a wireless PCM receiving circuit, 24,2
5.26 is a timing extraction circuit, 27, 28.29 is an elastic store LSI, 30.31.32 is a PCM assembly circuit, 33 is a pulse branch circuit, 34 is a pulse inserter, 35.36 is a PCM transmission circuit, 37 is a wireless PCM transmission It is a circuit.

The operation of the repeater 711 will be explained below with reference to FIG. Output of digital exchange 5'...Iue (PC from 57b)
The M signal is received by the PCM receiving circuit 21 and once written into the elastic store LSI 27 using the clock extracted by the timing extraction circuit 24 via the PCM receiving circuit 21. Next, this PC with bad writing
The M signal is read out and guided to the PCM frame assembling circuit 30, where jitter occurring during transmission is removed, and the same signal as the PCM signal on the outgoing highway 57b is reproduced.

This regenerated PCM signal passes through a pulse branching circuit 33, has its transmission conditions adjusted by a PCM transmitting circuit 35, and is transmitted to a lower repeater (not shown).

On the other hand, this PCM signal is sent to the pulse branching circuit 33 by separating only the time slot assigned to the telephone terminal #111 housed in the repeater 711 and sending it to the decoder 2.
0b restores the voice current of the other subscriber and returns the telephone receiver 20.
lead to a.

Next, the PCM signal returned and transmitted by the lowest repeater (not shown) is received by the PCM receiving circuit 22, and this PCM signal is sent to the elastic store LS.
I28&] is written by the clock extracted from the timing extraction circuit 25N via the PCM receiving circuit 22. The readout of the written PCM signal is performed using the i''L clock extracted by the timing extraction circuit 24 described above, and the jitter generated in the transmission path is removed from the PCM signal, and the PCM frame assembly circuit 31 The output of the PCM frame assembling circuit 31 is sent via the pulse inserter 34, the PCM transmitting circuit 36 adjusts the sending conditions, and the output is transmitted to an upper level repeater (not shown). subscriber terminal #11
The audio current from the transmitter 19a is converted into PCM by the coder 19b.
After being encoded, the pulse inserter 34VC inserts it into the time slot portion assigned to subscriber terminal #11.

Output to mobile terminal #17: P from iway 57b
The CM signal is branched from the PCM frame assembly circuit 30 and sent out from the wireless PCM transmission circuit 37 at a radio frequency f, and the PCM signal from mobile terminal #417 is sent out at a radio frequency f2 and sent to the wireless PCM reception circuit. 23, and the wireless PCM is sent to the elastic store LSI 29.
It is written using the clock extracted by the timing extraction circuit 26 via the reception circuit 23. This written PCM signal is read out by the timing extraction circuit 24 described above.
This is done using a clock extracted by

As a result, the PcM signal is guided to the PCM frame assembling circuit 32 with jitter generated during wireless transmission removed.

The output of the PCM frame assembling circuit 32 passes through the pulse inserter 34, has its transmission conditions adjusted by the PCM transmission circuit 36, and is transmitted to the highway 57a.

In this case, the PCM sent to the input highway 57a
Only the time slot assigned to mobile terminal #17 is rewritten in the signal pattern, but if there is a risk that a time slot other than the time slot assigned to mobile terminal #I7 may be rewritten by mistake, 1
When registering 7 (at the time of departure of the mobile terminal), this mobile terminal 1
A command to guard all time slots except the time slot assigned to No. 17 is transmitted to each repeater. This prevents a time slot that is not the time slot assigned to mobile terminal #17 from being erroneously rewritten. The method of transmitting the command to guard the time slots described above can be easily realized using a known method, for example, an out-slot signal method using a specific time slot of the PCM signal pattern, such as time slot number 16 (empty time slot) in FIG. It is possible.

In addition, changes in the time slot assignments of repeaters and mobile terminals can be made by a time slot assignment circuit (TSAC) MC, which is an IC manufactured by Motorola, for example.
This can be easily achieved using I4418. That is, PCM
By connecting the above-described time slot assignment circuit 38 between the frame assembly circuit 32 and the pulse inserter 34, only registered time slots are guided to the pulse inserter 34.

Although the wireless system of mobile terminal #17 has not been described above, since the application area of the digital mobile wireless system according to the present invention is limited to those along roads or tracks, leaky coaxial cables and other nearby electromagnetic Transmission lines can be constructed by appropriately combining field transmission systems and known transmission systems such as optical communications for straight sections of roads and tracks, thereby making it possible to use radio waves effectively.

Furthermore, a transmission delay time occurs due to the length of the transmission path connecting the highways in and out of the digital exchange. In other words, there is a limit to the length of the transmission path, but the propagation speed of the transmission path can be reduced to 150 jan/
As, the loop length is 75Icpn/mS, and a typical telephone can tolerate a delay time of about 20m5. Therefore, the loop length of the road and track is 1500t.
It is allowed up to an, and there are no practical restrictions.

As described in detail above, according to the present invention, the construction of a switching network that accommodates mobile terminals whose movement range is limited along tracks, along roads, etc. is possible without the conventional tracking switching system that requires complicated switching control. In addition, even if a large number of mobile terminals are accommodated, it is possible to make calls using two radio frequencies, one for transmitting and one for receiving, per highway for the entry and exit of digital exchanges, thus making it possible to use radio waves more effectively. It has the characteristics of a dog.

In the above description, one embodiment of the digital mobile radio system according to the present invention has been shown, but it will be obvious that various modifications and changes can be made without departing from the spirit of the present invention.

[Brief explanation of drawings]

1 and 2 are diagrams showing an example of a conventional telephone switching network configuration, FIG. 3 is a configuration diagram showing an embodiment according to the present invention, and FIGS. 4 and 5 are diagrams showing a PCM primary group according to the present invention. FIG. 2 is a configuration diagram showing an example of a frame structure and an embodiment of a repeater. 1.2.3...Subscriber terminal group, /1,5.6...Switching equipment, 7-10...Multiplex transmission line, 11-16...Multiplex transmission equipment, 17...Mobile terminal, 5′...Digital exchange, 18・Holding memory, 21・Subscriber circuit group, 51
~58...Entry/exit highway, 51a-58a...Inbound highway, 51b-58b...Outbound highway, 71,
78...Line interface section, 71a...Ink face on transmitting side, 71b interface on receiving side,
701~## 730...Repeater, 1~30...Subscriber terminal, #
17・Mobile terminal, 19・Transmitter, 19a...Speaker, 1
9b... Korg, 20... Receiving section, 20a receiver, 20b... Decoder, 21.22... PCM receiving circuit,
23... Wireless PCM receiving circuit, 24. ．． 25.26 ・
・Timing extraction circuit, 27, 28.29...Elastic store LS I, 30, 31.32...PCM
"Frame assembly circuit, 33...Pulse branch circuit, 34 Noculus inserter, 35.36. PCM transmission circuit, 37
...Wireless PCM transmission circuit, 38 Time slot assignment circuit, fl Reception frequency, f2...
Transmission frequency. Patent applicant Japan Radio Co., Ltd.

Claims (2)

[Claims] (1) Subscribers accommodated in each of a plurality of repeaters inserted at predetermined intervals in the transmission line connecting some or all of the outgoing highways and incoming highways of the digital exchange A digital mobile radio switching system characterized by having an allocation means for allocating predetermined time slots to a terminal and a mobile terminal moving along the transmission path. (2) The feature includes a notification means for notifying the plurality of repeaters of time slot information allocated to the mobile terminal, and a setting means for arbitrarily setting a time slot used for communication with the mobile terminal. A digital mobile radio system according to claim 1.