JPH1174991A - Communication device and its control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve convenience by providing an ISDN line with a reference point, a subscriber line after a U point with an NT1 and a DSU unit with a terminal adaptor(TA) dedicated S/T point interface. SOLUTION: Relating to a multivalued DSU board, a DSU chip 5 and a DSU interface circuit part 6 consist of a DSU interface 7 and an S/T point bus priority competition connection circuit. Relating to this device, an ISDN line is provided with a reference point, a subscriber line after a U point is provided with an NT1 and a DSU unit is provided with a TA dedicated S/T point interface. That is, the device can directly connect a TA 19 to the DSU interface 6 without the intervention of a high frequency transformer and has both a port 14 and a conventional S/T point interface port 13. Here, B is directly connected to the new function port 14, and a CPU 18 and an S/T interface chip 17 are added to configure the TA 19.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a U-point interface section of an ISDN (Integrated Services Digital Network) line, which has been rapidly developing in recent years, and more particularly to an interface control with an Internet terminal connected to a subscriber line. is there.

[0002]

2. Description of the Related Art The spread of the Internet has been remarkable.
A number of businesses have started using this technology, and the conventional telephone network is no longer able to handle it. The demand for the Internet has risen, and it has now become a hindrance to regular telephone communications.

[0003] Focusing on the use of high-speed ISDN, not only high-speed but also eight terminals on one line and three terminal devices via TA can be connected, so that this economic effect is great.

[0004] The Internet has revolutionized the economic structure. Home offices have grown significantly, allowing them to work from home. It is very natural that inexpensive OA equipment is required as more private entrepreneurs work at home.

[0005] Personal computer (PC), facsimile (FA
X) Alternatively, a digital copier, a printer, and a multifunctional telephone are essential devices. Conventionally, these OA devices and communication lines are in principle 1: 1 terminals, and one terminal is required for each terminal.

With the introduction of the ISDN line, a plurality of terminal devices can be connected to one line via a TA. However, the interface was complicated and expensive.
Although convenient for large and medium-sized systems, it is not convenient for individual users including home offices.

[0007]

There is a need for a system that can cover from individual users to large-scale users, and that has flexibility in the system according to the purpose. That is, there is a demand for a terminal capable of covering from one to three individual users to a medium-sized system having ten or more terminal devices, and at a low price.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to efficiently mount necessary functions on an NT1, that is, a DSU unit to meet the purpose.

[0009]

In order to achieve the above object, a communication apparatus according to the present invention has the following functions. That is, in addition to the conventional S / T point bus interface, TA S / T
The port of T point / interface is provided.

The interface at the S / T point for the TA uses a newly devised circuit and omits the conventional high-frequency transformer. Therefore, the size and weight can be reduced, and the economic effect is great.

If the conventional S / T point, bus interface and port are removed and only the TA port is used as needed, an inexpensive system for individual users can be obtained. In other words, it is scalable, and a lost system can be provided.

[0012] By using an S / T point bus interface and a TA interface port, which can be used for a large-scale system, it is possible to connect to ten or more terminal devices. As a feature of the present invention, priority can be given to the TA port, so that important or frequently used terminal equipment can be connected to this port to further improve the usability.

For a user who demands a simpler and cheaper system, the TA function, that is, the CPU and the S / T interface chip may be integrated into the DSU board. Since the functions of DSU and TA are all included in NT1, the convenience is further improved.

[0014]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

The present invention relates to a communication interface after the U point of ISDN, which has been remarkably developed due to the spread of the Internet in recent years.

The widespread use of the Internet has been so significant that the rapid increase in traffic
TN (telephone network) has become unable to follow. So I
The number of subscribers to SDN keeps increasing, and the number of subscribers cannot keep up.

In particular, the demand for SOHO, that is, small businesses and homes, is rapidly increasing. Therefore, a DSU (Digital Service Unit) and a TA (Terminal Adapter) that can be added and installed by a simple user's own hand are required.

[0018] Hopefully, if these are integrated and convenient, and if they are inexpensive, it is better. The spread of the Internet, in other words, is the information and communication revolution of social infrastructure,
We are changing our social and economic activities.

The increase in the number of lines cannot respond to the increase in the Internet, and the ITU (World Telecommunication Union) has adopted B-ISD
We are promoting the expansion of N (High Bandwidth ISDN) ATM networks and satellite communication networks. However, at present, it is difficult to respond immediately, especially in the United States, and how to shorten the Internet access time with the conventional network is focusing on providing services to users.

Therefore, at present, speeding up in the PSTN network has been proposed, and standardization of an asymmetric 56 Kbps, pcm modem is urgently required. However, this is a current symptomatic treatment and not a fundamental solution. Basically, there is an urgent need to build an ISDN on a global scale.

The ISDN uses the DSU as an interface, and all terminal devices (PC, FAX, telephone, etc.) are connected to the network. This DSU is called NT (Network Terminal) and serves as an entrance to ISDN. The basic structure of the ISDN basic interface consists of two user information transfer B channels having a transmission rate of 64 kbps and 16 kbps.
D channel for transferring signal information with high speed, ie, 2B + D
Consisting of

The functional configuration of the ISDN subscriber system is NT1
(Network terminating device 1: DSU), NT2 (network terminating device 2) and the like do not always match the actual device configuration. The interface point between NT1 and NT2 is called a T point, and this T point is a boundary point with the user network.

TE1 (ISDN standard terminal: telephone, FA
X, etc.) and the interface point between NT2 is called S point,
When a device such as a PBX is not used, NT2 does not exist and the points S and T coincide. In such a case, S / T
I call it a point.

In general small offices and homes, the PBX is not used in many cases, so the points S and T coincide.

When the user wants to connect an existing terminal to the ISDN and use the terminal, the TA sets the signal function of the terminal and the D channel
Interface protocol. That is, the TA has a protocol / interface conversion function for connecting to the ISDN in response to the user's request.

In view of the above-mentioned situation, the present invention proposes a multifunctional DSU device in which NT1 and NT2 are integrated to meet the needs of Internet users, which are explosively spreading in the present invention.

The main part of the DSU and the interface, which is a feature of the present invention, is disclosed in Japanese Patent Application No. 9-106556 (communication device and its control system), and in the mounting system and applied examples, it is disclosed in Japanese Patent Application No. 9-167847 (communication device) And its mounting method).

In the present invention, for the purpose of user's convenience, a multi-functional, interface unit including peripherals is made into a custom LSI by a unique circuit system, and the size of the interface unit is reduced.
The feature is that it is thinner and lighter.

FIG. 1 shows a system configuration according to the present invention. Reference numeral 4 denotes a multifunctional DSU board which is the main feature of the present invention. DSU chip 5, DSU interface circuit section 6
Is composed of 7 DSU interfaces and 8 S / T point bus priority / contention control circuits.

It is connected to the DSU interface circuit 6 via sockets, connectors, 2 and 3 at point U from the ISDN network, ie, via a reference point indicating a cut between the network and the house.

9 is a line polarity switch, and 10 is an LED lamp indicating the polarity. LED1 when connected to reverse polarity
0 repeats blinking. Lights up when the polarity is normally switched by the switching switch 9.

In FIG. 1, A indicates a DSU section S / T point interface. This is exactly the same as the conventional method.
B is directly connected to the new function port 14 according to the present invention, and CP
U18 and S / T interface chip 17 are added. In short, a TA (terminal adapter) 19 is configured.

The S / T interface chip 17 uses, for example, MC145574 (trade name, Motorola, USA). Unlike the prior art, there is no need for a connection high-frequency transformer, and the connection can be made directly through the connector 14 of the DSU board 4.
The advantage of the direct connection is that the high-frequency transformer and its peripheral parts are no longer necessary, so that not only a small space but also a cost reduction can be achieved.

In FIG. 1, A is a conventional S / T point interface bus, which is connected to the DSU interface 6 through high frequency transformers 11 and 12 through a connector 13. Reference numeral 16 denotes an external power supply line for supplying power to the S / T point bus.

A feature of the present invention is that the TA 19 can be directly connected to the DSU interface 6 without passing through a high frequency transformer, and has both the port 14 and the conventional S / T point interface port 13. When a large system is configured, if 13 and 14 ports are used together, a maximum of 8 terminals can be connected by 13 and three terminal devices can be connected by 19 TAs.

Further, in the case of a small office such as a home office, if only the part B is used without using the part A, a very simple apparatus can be obtained. Further, the port 14 is a conventional S /
Since it can be directly connected to the T bus interface chip, software and hardware developed conventionally can be used without any change.

FIG. 2 shows a priority / contention control circuit. When a plurality of TEs (terminal devices) are connected to the bus of the basic interface, the D channels are always shared by these TEs for signal information and packet / data transfer.
Therefore, an access conflict may occur when a plurality of TEs try to start sending signals to the D channel at exactly the same time.

When this access conflict occurs, one T
A procedure in which transmission of only the signal E is finally completed is defined as an access contention procedure. Multiple T
When a signal is sent from E to a bit of a certain D channel at the same time, a logic (0) having a negative level potential wins over no signal (1). Therefore, (0) and (1) are simultaneously different TEs.
, The DSU interprets this bit as (0).

In this case, at (0), TE always outputs a negative level potential. This is because if the signals of the positive level and the negative level are output simultaneously, the potential becomes unstable. The DSU copies each bit of the D channel received from the TE side to an E (echo) bit and sends it to the TE side.

This is because each TE compares the D channel bit transmitted by itself with the content of the next received E bit, and if it is the same, continues to transmit a signal on the D channel; . Eventually, only signals from one TE continue to be transmitted. At this time, the TE that has stopped transmitting the signal
Next, when the D channel becomes empty, the signal transmission is retried.

The determination as to whether the D channel is free or in use is based on the characteristics of the signal transmitted by each TE on the D channel. The signal that each TE sends to the D channel has the form of a layer 2 frame.

The first and last bits of the layer 2 frame are (0), and no six consecutive "1" s appear in the frame at the maximum. On the other hand, when no TE transmits a signal to the D channel, it is (1) as a no signal.

When seven or more (1) s appear continuously on the D channel, seven or more (1) s are continuously observed in the copy of the E bit. Therefore, the TE determines that the D channel is free.

It is at this E that the TE begins to send a signal.
This is done by observing a certain number of consecutive (1) bits. The contention control can be performed by changing the signal to transmit the number of continuations.

The prescribed value of the number of continuations is 8 for a signal frame in a normal case, and 10 for a user packet. On the other hand, in order to prevent one TE from occupying the D channel, immediately after transmitting one frame, the number is set to 9 for a signal frame and 11 for a packet frame.

As a result, each TE can use the D channel almost equally, and a frame containing call control information is transmitted in preference to a packet. The fact that this number is set to 8 instead of 7 at the minimum is a safety measure against the case where each TE erroneously counts.

AMI on basic access line
(Alternate Mark Inversio
n) Since a code is used, it is sent as a ternary signal. In the 100% AMI code, (0) of the digital signal is a positive or negative electric pulse having a full width (100%) of its time length, and (1) is sent as a no-signal of zero potential. In addition, there is a rule that normally adjacent (0) has a potential of a positive polarity and a potential of a negative polarity alternately.

The priority / contention control circuit of FIG. 2 is constructed in view of the above. First, the AMP differentially amplifies the input signal of the S / T point bus input via the transformer T1, and generates a ternary converter signal. COMP1
COMP4 is a comparator for generating a conflict control signal. The L level signal survives between the comparators and U
1, H level through U2, TAP, TBN
Given to. The contention control circuit is composed of a comparator and a logic circuit, but this circuit shows one example. With the same configuration, the present conflict control circuit can be realized even if the inner logical relationship is changed.

As described above, the TA 19 connected to the port 14 is given priority in FIG. 1 as a feature of the present invention. In the priority / contention control circuit of FIG.
The relay RY is driven by the CPU of the TA19 via the U6 to the U interface 7 to open the output of the transformer and open the outputs of the comparators COMP1 and COMP2.

When RY is ON, the terminal TE connected to TA is given priority. That is, during this time, the terminal connected to the S / T point bus cannot be accessed by the priority control.

In FIG. 2, INFO1 is a calling signal, CO
MP5 is a hysteresis converter. The input palace signal is integrated, a call signal is detected by COMP5, and I
Input to NFO1.

In FIG. 2, T1 and T2 indicate high frequency transformers. When there is no signal at RAP and RBN, U
3, the output of U4 becomes high impedance, no current flows in T2, and shows no signal potential 0. When RAP goes high, the output of U3 goes high and the output of U4 goes low,
A positive polarity palace occurs at T2. Similarly, RBN is H
At the level, a negative polarity palace occurs at T2.

FIG. 3 shows an example of connection of the DSU board 4.
The reference numerals are the same as those in FIGS. S / T at port 13
A TA is connected to the point bus and the port 14. As mentioned above, for small users, 13 ports are removed and only 14 ports are used.

A terminal denoted by reference numeral 31 can be connected to the 15 S / T point buses from TE1 to TE8. The TA connected to the port 14 is 32, TEm1, TEm2, TE
Three terminals m3 are connected.

The terminal groups connected to the ports 13 and 14 are prevented from collision by the priority / contention control circuit on the 4 DSU board. As a feature of the present invention, TA19 S
To the terminal connected to the / T interface chip 17,
It is possible to give priority according to a command from the CPU 18.

FIG. 4 shows a conventional example. The symbols are the same as in the previous figure. The port is only an S / T point bus interface, and high frequency transformers 11, 12, 42 and 43 are interposed. The contention control is performed on the S / T bus by a known technique.

The conventional DSU board 41 requires a high-frequency transformer, has a large area, and is expensive. Also, due to the spread of the Internet, use by small users has not been considered. TA (constituted by 17 and 18 in FIG. 4) is T connected to the S / T point bus.
E.

According to the present invention, it becomes possible to mount a TA function on a DSU board. As a simpler DSU unit (NT1), an S / T point interface 17 and a CPU 18 are mounted on a board 51 as a unit with the DSU unit as shown in FIG.

A DSU board with a TA is mounted on NT1 (line termination) immediately after the U point, and the home is transformed into a small office as shown in FIG.

In FIG. 6, reference numeral 51 denotes a DSU with TA, unit, 62 denotes a personal computer, 63 denotes a FAX or digital copier, and 64 denotes a telephone. 61 is the house itself, 1
Indicates a public network.

As described above, according to the present invention, in order to cope with the Internet that has been rapidly spreading in recent years, the DS
The U unit is provided with a port for directly connecting an S / T point interface that does not require a high-frequency transformer, and this port interfaces with the TA.

Therefore, the terminal equipment conventionally used,
For example, a personal computer, a facsimile, and a telephone can be used as they are.
An efficient home office is created by adding this device to one RSDN line and one analog line using an ISDN line.

As described above, according to the present invention, a rapidly increasing number of home offices can be realized with a single ISDN line, which not only contributes to the Internet business, but also allows conventional office equipment to be used as it is. The effects of effective use of software and hardware resources are immeasurable.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a communication control device according to an embodiment.

FIG. 2 is a diagram illustrating a main part of a priority / contention control circuit of the communication control device according to the embodiment;

FIG. 3 is a diagram illustrating connection with a terminal device according to the embodiment;

FIG. 4 is a diagram showing a conventional communication control device.

FIG. 5 is a diagram illustrating a DSU unit with a built-in TA (terminal adapter) according to the embodiment;

FIG. 6 is a diagram showing a form of realizing a home office according to the present embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Public network 2 U point connector 3 U point socket 4 DSU board 5 DSU chip 6 DSU interface part 7 DSU interface circuit 8 Priority / competition control circuit 9 Polarity change switch 10 Polarity display LED lamp 11, 12 High frequency transformer 13 S / T point Bus interface port 14 TA port 15 S / T point bus 16 Power supply line 17 S / T point interface chip 18 CPU 19 TA (terminal adapter) 31, 32 Terminal equipment 41 DSU unit 51 TA built-in DSU board 61 House 62 Personal computer 63 FAX / digital copier 64 Telephone

Claims (4)

[Claims] 1. A DSU board comprising a DSU chip, a DSU interface circuit, a terminal device priority / contention control circuit, an S / T point bus interface port, and a directly connected TA (terminal adapter) interface port. A communication device characterized by improved convenience by connecting to ISDN subscriber line and point U, and downsizing. 2. The DSU board according to claim 1, wherein
A communication device comprising a priority control circuit in an interface circuit unit, wherein a priority is given to a terminal device connected to a TA by a signal means from a CPU of the TA. 3. The communication device according to claim 1, wherein the contention of the signal of the S / T bus port and the contention of the signal of the TA port are adjusted using means of a contention control circuit. 4. The method according to claim 1, wherein a CPU and an S / T point interface chip are mounted on the NT1 and DSU boards.
A communication device that incorporates the function of a TA into NT1 and is characterized by miniaturization and cost reduction of the device, and improvement in operability and use efficiency.