JP2594615B2 - ISDN terminal adapter device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a terminal adapter device of an ISDN interface system.

[Conventional technology]

The ISDN terminal adapter device is installed in the subscriber's premises and is a device for accommodating existing terminals in the ISDN network. The ISDN terminal adapter device transmits call control signals for circuit-switched data terminals, packet-switched data terminals, telephone terminals, voice terminals, etc. In addition to converting to channel protocol, conversion of user speed of existing terminals and transmission rate in ISDN, and conversion of electrical and mechanical interfaces are performed.

Conventionally, when a plurality of existing terminals are accommodated in one ISDN terminal adapter device, it is configured as shown in FIG.

Referring to FIG. 3, a conventional ISDN terminal adapter device (TA) includes a common unit (COM) 10 and a terminal interface unit (R).
INF) 21 to 2n, and a common unit 10 includes a microprocessor (MPU) 13, a memory circuit 14, and its peripheral circuits 15
The peripheral circuits include an interrupt circuit, a timer circuit, a direct memory access control (DMAC) circuit, and the like. As an access circuit to the ISDN network, S
It comprises an interface circuit 11 and a LAPD circuit 12.
On the other hand, the terminal interface units 21 to 2n are respectively terminal accommodation circuits 213, 223,.
.. 2n2 and B channel selection circuits 211, 221... 2n1.

Next, the operation will be described with reference to FIG. For example, when the existing terminal DTE1 is a terminal having the protocol of CCITT Recommendation X.21, the terminal accommodating circuit 213 of the ISDN terminal adapter device TA supports the function of performing electrical and mechanical conversion and the hardware of the X.21 protocol. In the above configuration, the microprocessor 13 of the common unit 10 performs X.21 protocol processing for an outgoing call or an incoming call from the existing terminal DTE1, and performs an S interface with the LAPD circuit 12 with the ISDN network. Using the circuit 11, ISDN protocol processing is performed via the D channel at the S / T point recommended in CCITT Recommendation I.430.

According to the above protocol processing, when data transmission / reception can be performed using the B1 channel and the B2 channel at the S / T point recommended by CCITT recommendation I.430, the user terminal of the existing terminal and the ISD
The transmission rate is converted in N, and the B channel selection circuit 211 is operated to select the B1 channel or the B2 channel to transmit and receive data. Hereinafter, the interface protocol of the existing terminal devices DTE2 to DTEn differs depending on the terminal type, but the operation is the same as that described above, and a description thereof will be omitted.

[Problems to be solved by the invention]

The above-mentioned conventional ISDN terminal adapter device has a user speed of an existing terminal device as low as 2.4 Kb / s or a terminal device of 64 Kb / s.
s, and fast terminal equipment, one of the two B channels
Occupy one. Therefore, three or more existing terminals
There is a problem that only two terminals can be used at the maximum even if accommodated in the ISDN terminal adapter device.

[Means for solving the problem]

An ISDN terminal adapter device according to the present invention includes a microprocessor, a memory circuit and its peripheral circuits, an S interface circuit, and a LAPD circuit, and is connected to an ISDN network, a physical and electrical interface with the ISDN network, protocol processing, and the entire device. A common unit that controls the connection, connected to the common unit via an internal bus and a channel data bus, connects a terminal having the existing communication network interface, and a physical / electrical interface with the connected terminal, transmission rate conversion, The terminal interface unit includes a plurality of terminal interface units that perform protocol processing, and the terminal interface unit includes the following circuits.

(1) A terminal accommodating circuit for connecting a terminal having an existing communication network interface and performing protocol processing via a physical and electrical interface with the terminal and the common unit (2) Connected to the terminal accommodating circuit Speed conversion circuit that converts the transmission rate of the terminal to the intermediate rate that is a positive multiple of 8 Kb / s (3) B-channel frame with 8 Kb / s capacity per slot and 8 slots In the above, the slot position used by the terminal is specified by the common unit, and in the case of transmission, the output data of the speed conversion circuit is arranged in a slot of a B channel, and in the case of reception, the data on the frame of the B channel is assigned. Subrate demultiplexing circuit that extracts from the slot and outputs to the speed conversion circuit. (4) B1 channel or B2 channel to be used And al selected, connects to the channel data bus B
Channel Selection Circuit [Embodiment] Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 2 is an explanatory diagram for explaining the operation of the embodiment.

Referring to FIG. 1, an ISDN terminal adapter device TA according to one embodiment of the present invention comprises a common unit (COM) 10 and terminal interface units (RINF) 21 to 2n. The common unit 10 has a microprocessor (MPU) 13, a memory circuit 14, and its peripheral circuit 15. The peripheral circuit 15 includes an interrupt circuit, a timer circuit, a DMAC circuit, and the like. An access circuit to the ISDN network includes an S interface circuit 11 and a LAPD circuit 12.

Further, the terminal interface units (RINF) 21 to 2n include terminal accommodation circuits 213, 223,... Which accommodate the existing terminal devices DTE1 to DTEn.
2n3, speed conversion circuits 212, 222,... 2n2, sub-rate demultiplexing circuits 214, 224,.
1, 2n1, and the firmware interface with the common unit 10 is connected to the S interface circuit 11 of the common unit 10 through the common bus (CBUS) and the transmission / reception data is passed through the channel data buses (B1, B2). Is done.

Next, the operation will be described with reference to FIG. 1 and FIG. For example, when the existing terminal DTE1 is a terminal having a protocol of CCITT recommendation X.21, the terminal accommodation circuit 213 of the terminal TA has a function of performing electrical and mechanical conversion and a function of hardware supporting the X.21 protocol. In the above configuration, the microprocessor 13 of the common unit 10 responds to a call from the terminal DTE1 or an incoming call.
Performs the X.21 protocol processing and uses the LAPD circuit 12 and the S interface circuit 11 to connect to the ISDN network.
Perform ISDN protocol processing via the channel. S / S recommended by CCITT Recommendation I.430 by the above protocol processing
When the B channel at point T becomes available, the speed conversion circuit 212
Subrate demultiplexing circuit 214, B channel selection circuit 211
Operates upon receiving an instruction from the microprocessor 13 of the common unit 10.

The flow of communication data from the plurality of existing terminals DTE1 to DTEn to the ISDN network and from the ISDN network to the plurality of existing terminals via the B channel will be described below. For example, existing terminal equipment DTE
1, DTE2, and DTEn are communicating, and the existing terminal device D
User speed of TE1 is 2.4 Kb / s, user speed of existing terminal device DTE2 is 19.2 Kb / s, user speed of existing terminal device DTe is 9.6 Kb
/ s, the communication data that has passed through each terminal accommodation circuit 213, 223, 2n3 does not change and the next speed conversion circuit 212, 22
Input to 2,2n2. Here, 2.4 from existing terminal equipment DTE1
The communication data of Kb / s is converted by the first transmission speed conversion circuit 31 into communication data of 8 Kb / s at an intermediate rate. Similarly, the user speed 19.2 Kb / s of the existing terminal device DTE2 is changed to an intermediate rate of 32 Kb / s, and the user speed 9.6 Kb / s of the existing terminal device DTEn.
s is converted to an intermediate rate of 16 Kb / s, respectively, and the second transmission speed conversion circuit 32 in FIG.
The data is converted into communication data having a frame structure of 64 Kb / s shown in FIG. 2, and the microprocessor 13 of the common unit 10
Is shifted to the designated slot having an 8-bit (slot) configuration per frame and output to the B channel selection circuit 211.

Next, assuming that the instruction from the microprocessor 13 of the common unit 10 is B1 in the transmission B channel selection circuit 34 of the B channel selection circuit 211, each communication data is output to the transmission side of the line B1 and is output to the transmission side of the line B1 in FIG. Is input to the S interface circuit 11 of the common unit 10 and transmitted from the S interface circuit 11 to the ISDN network. The communication data from the ISDN network is subjected to a process reverse to the above operation by a receiving B channel selecting circuit 41, a sub-rate separating circuit 42, a second receiving speed converting circuit 43, and a first receiving speed converting circuit 44. , To the existing terminal device.

〔The invention's effect〕

As described above, the present invention provides a sub-rate demultiplexing circuit between a speed conversion circuit and a B channel selection circuit of an individual terminal interface circuit of an ISDN terminal device to perform demultiplexing of a B channel of an ISDN basic interface. Accordingly, there is an effect that a maximum of 16 existing terminals can be accommodated in one ISDN terminal device.

[Brief description of the drawings]

FIG. 1 is a block diagram of an embodiment of an ISDN terminal adapter device of the present invention, FIGS. 2 (a) and 2 (b) are explanatory diagrams of an embodiment of the present invention, and FIG. 3 is a diagram of a conventional ISDN terminal adapter device. It is a block diagram. TA: ISDN terminal adapter device, DTE1-DTEn: Existing terminal device, 10: Common part (COM), 21, 22,..., 2n Terminal interface (RINF), 11: S interface circuit, 12
…… LAPD circuit, 13 …… Microprocessor (MPU), 14
…… Memory circuit, 15 …… Peripheral circuit, 211,221,… 2n1 ……
B channel selection circuit, 212,222, ... 2n2 ... speed conversion circuit, 213,223, ... 2n3 ... terminal accommodation circuit, 214,224, ... 2n4 ...
... Subrate demultiplexing circuit.

Claims (1)

(57) [Claims] 1. A terminal having an existing communication network interface.
An ISDN terminal adapter device connected to an ISDN network, including a microprocessor, a memory circuit and its peripheral circuits, an S interface circuit, and a LAPD circuit, and connected to the ISDN network.
A common unit that controls a physical and electrical interface with the ISDN network, protocol processing, and control of the entire device, and a terminal that is connected to the common unit by an internal bus and a channel data bus and has the existing communication network interface. A physical and electrical interface with the connection terminal, a plurality of terminal interface units that perform transmission rate conversion, protocol processing, the terminal interface unit connects a terminal having the existing communication network interface,
A terminal accommodating circuit that performs protocol processing via the physical and electrical interfaces and the common unit with the connection terminal, and a transmission rate of a terminal connected to the terminal accommodating circuit and a positive multiple of 8 Kb / s. A speed conversion circuit for converting a transmission rate to an intermediate rate; and in a B channel frame having a capacity of 8 Kb / s per slot and consisting of 8 slots, a slot position used by the terminal is specified by the common unit. A sub-rate multiplexing / demultiplexing circuit for arranging output data of the speed conversion circuit in a B-channel frame in the case of transmission, extracting data on the B-channel frame from the slot in the case of reception, and outputting the data to the speed conversion circuit; Select the B channel to be used from the B1 channel or the B2 channel, and select the B channel to be connected to the channel data bus. ISDN terminal adapter device being characterized in that a road.