JPS5927645A - Customer station connection control system - Google Patents

Abstract

PURPOSE:To decrease the connection delay time, by performing an occupying request of incoming line channel from plural terminals at random through the use of a bit. CONSTITUTION:A digital service unit 1 and terminals 2-1-2-N are connected via an incoming line 3 and an outgoing line 4. When the terminals 2-1-2-N use a data signal channel, the control is performed with a control signal channel. An output pulse of one set among the terminals 2-1-2-N is received at the unit 1 as a V volt. When the control signal channel occupying request from n-set of the terminals 2-1-2-N is given at the same time, it is received at the unit 1 as an nV volt and when the unit 1 receives the pulse of 2V volt, the collision of the request from the plural terminals 2-1-2-N is detected. The unit 1 transmits a signal stopping once the request of the terminals 2-1-2-N and the terminals 2-1-2-N transmit again the request signal after a waiting time at random.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Description of the field to which the invention pertains The present invention provides a method for multiplexing and concentrating a plurality of terminals by bus connection, and is particularly applicable to the future l5DN (digital comprehensive service network). (2) Description of conventional technology In 15DN, all communications are performed in a digital manner, and digital signals are passed from subscriber to subscriber. In other words, end-to-en
d digital connection will be realized. Therefore, each subscriber connects various terminals to enjoy various services, and uses the digital pipe (the concept of a channel through which digital signals can pass) provided to the subscriber efficiently (for example, to Try to use it by sharing it with a device.

Although the thickness of the digital pipe (channel capacity) may vary depending on the requirements of each subscriber5, a standard value (for example, 64 kbps x 2+α) will be determined.

First, I will explain what a standard digital pipe (as currently envisioned) is. The channels are divided into three types and are applied in the form of B+B+D. This form is called the basic access form.

Here, B is a bit rate of 64 kbps
It usually passes through voice and PCM encoded signals or data signals of 64 kbps or less. D has a bit rate of 8 to 16 kbps and is a channel for transmitting subscriber signal information (information used mainly for controlling the communication network, such as call connection). Therefore, in the basic access mode, two channels for voice or data with a bit rate of 54 kbps or less and one channel for signal are provided. Therefore D
A channel is shared among multiple communication channels.

If you want to connect a large number of terminals (for example, N) with basic access as described above, it is necessary to concentrate and multiplex the information from the N terminals onto two B channels, and the signals from the N terminals must be multiplexed. Information needs to be combined into one D channel. FIG. 1 shows the basic configuration of the basic access that is to be realized here. In Figure 1, 1
is a DSU (Digital 5 service unit)
) and connect the digital pipes of B +B +D to the station (
It has an interface with a home bus, a transmission interface with a station (for example, an interface for burst mode time-division transmission), and a speed conversion function. Further, 2-1 to 2-N are N terminals (Subscriber Terminals).
@Represents.

It is assumed that the in-home digital bus in FIG. 1 is a full-duplex communication bus. At this time, multiple terminals simultaneously
If they tried to access the channel, a collision would occur, disrupting the exchange of signal information. Therefore, this configuration requires bus collision control.

The above configuration is similar to a bus-configured local area network (for example, Ethernet), and the local area network can be regarded as a conventional technology. Typical bus collision control methods used in local area networks are shown below.

■Centralized control method 0 polling method This is a method in which a centralized controller calls each terminal in turn, but the DSU must have a control function, and extra bits are required on the frame to specify the temperature of each terminal. I don't like it very much because of this.

0 request/assignment method This is a method of issuing a re-fuestration from the terminal, but it is the same as above.

■0 Distributed control type o C8MA/CD method (Carrier 5ense
Multi, Access/Collision D
etc.) Widely used in Ethernet, etc., it is a method that detects the presence or absence of a signal and sends out its own signal if there is no signal. However, if multiple terminals simultaneously detect the idle state of the channel In this case, a collision occurs.Therefore, it is necessary to perform collision detection and enter a retry sequence.

When this method is applied to a terminal interface for basic access, the following problems may occur.

B. Since the D channel has 1 to 2 bits/frame, the carrier sense is far apart.゛Signal information is destroyed when a collision occurs.

0 Token Passing
) When the channel is idle, token packets are flowing on the bus, and when a terminal captures the token packet that gives it permission to send, it sends the data it wants to send onto the bus. If there is no data to send, a token packet is sent to give permission for the next terminal to make a call. Thus, following a kind of chain, the terminal j
Because number □□□ has the right to transmit, collisions on the bus can be avoided. In the case of this method, it is necessary to give an address to the terminal, and since the token packet also passes through the terminal t which has no data to send, there are problems such as a long waiting time for sending data.

(3) Purpose of the Invention The present invention provides a collision detection circuit only in the DSU in order to eliminate these drawbacks in the bus connection basic access of the 15DN, and each terminal detects a free control signal channel on the line. D S 'U detects whether there is a conflict of requests from multiple terminals and reports the result to each Z terminal, and if a conflict occurs, the terminal stops requesting. Then, connection control is performed by entering the try sequence again.The drawings will be described in detail below.

(4) Theory of structure and operation of the invention (1 male) Figure 2 shows one embodiment and structure of the present invention, and 1 is a DSU.
, 2-1. ..., 2-N are each terminal, 3 is the same uplink line,
4 is the down line, 5 is the line termination connected to the subscriber line, 6 is the circuit termination, 7
is a collision detection circuit, 8 is a driver, and 9-1. ..., 9-
N is each leg current drive tri-state driver, 10
．． 11-1. . . , 11-N each represent a receiver.

In addition, Fig. 3 (5) represents the downlink frame, and the third
Figure (g)) shows an uplink frame. In the figure, Bl and B2 are data signal channels, D is a control signal channel, 1.1 is a frame bit, ■ is an idle state), CD is a collision state indication bit, A is a control signal channel choke indication bit, and R represents a request instruction bit, and q represents a guard bit.

Further, FIG. 4 shows the configuration of an embodiment of a terminal suitable for the frame configuration shown in FIG. 3, where 9 and 11 correspond to those shown in FIG. a detection unit, 14 an information separation unit, 15 a decoding unit,
Reference numeral 16 represents a transmission control circuit, 17 a coding section, and 18 a multiplexing processing section.

FIG. 5 is a block diagram of one embodiment of the collision detection circuit 7 in the DSU, where 3, 4, 6, 7, and 8 correspond to those shown in FIG. 2, 19 is a receiver, and 20 is a request Reference numeral 21 represents an instruction bit amplitude monitoring section, 21 represents a control signal channel significant information detection section, 22 represents an available bit insertion section, and 23 represents a collision state instruction bit insertion section.

Terminals 2-1 to 2-N use data signal channels B1 and B2.
When using the control signal channel D, collision of occupancy requests for the control signal channel D becomes a problem because control is performed by the control signal channel. Control signal channel occupancy is achieved by setting R=1 on the uplink, as will be described later. In DSU, the output pulse of one terminal is ■ [volt]
Suppose that it is received as At this time, when control signal channel occupation requests are simultaneously issued from n terminals, the DSU receives an R-bit signal pulse with an amplitude of nV [volts]. Therefore, in DStJ [the amplitude of this pulse is 2
'V (volts), it means that requests from multiple terminals have collided. Figure 6 (5) shows the processing procedure of one embodiment at the terminal, and ) in Figure 6 shows the processing at the DSU. It shows the steps.

■ Assume that each terminal is initially in a dormant state or a waiting state for transmission. In this state, each terminal transmits 1L==Z (here, Z represents a high impedance state and 1°) and D=Z on the uplink frame.

■ In the DSU, R=Z and D=Z, so it becomes empty and DsU has A=1 on the downlink frame.
And CD=c)y is being transmitted.

(1) If there is a terminal waiting for transmission, since A=l, the terminal enters the requesting state and sends R=1 and D=Z-i on the uplink frame.

[Co., Ltd.] D8 U monitors the amplitude of the bit as described above, and if it is 2V [volt 3 or higher, it determines that a request conflict has occurred and sends A=0 on the downlink frame.
Sends CD=1.

■ The two terminals that issued the request set R; Z, D = z (request stop) because A=0 and CD=O, and after a random waiting time that varies depending on the terminal, return to ■.

If the pulse amplitude is V (volts), A=O and CD=Q are sent to permit occupation of the D channel.

After receiving A=O, CD=Q, the terminal that issued the O request enters a transmitting state and sends out "R=1 + D=l'-data". Correspondingly, the DSU also enters the busy state and A=O
Continue sending out CDMI0.

■ When the terminal in the transmitting state finishes transmitting, it enters the dormant state and sends out 1 (=ZkD=Z).

■ When the DSU detects R=Z and D=Z, it returns to the D channel idle state.

(5) Description of effects As explained above, according to the present invention, in a residential system with bidirectional bus connection, requests for uplink D channel occupancy from multiple terminals are made randomly using bit processing, so the connection delay is It has the advantage of being short. Also, collision detection is done by DSU.
Since the collision detection circuit is carried out within the 7.C.

[Brief explanation of the drawing]

ttc Figure 1 is a conceptual diagram of basic access, Figure 2 is an example of an embodiment to which the method of the present invention can be applied, and Figure 3 is an example format of a line frame and an uplink frame. 4 is a block diagram of an example of the interface section of each terminal, FIG. 5 is a block diagram of an embodiment of the collision control circuit in D8UK, and FIG. 6 is a block diagram of the processing section of the embodiment. In the figure, 1 is the terminal DSU 12-1 to 2-N, 3 is the uplink, 4 is the downlink, 5 is the line termination,
6 is a circuit termination, 7 is a collision detection circuit, 8 is a driver, and 9-1 to 9-N are constant current drives.
Tri-state driver, 10.11-1 to 11-N
is the receiver, 131°132 is the data signal channel, D
is a control signal channel, A is an aperture pull bit, CD is a collision state indication pit, It is a request indication bit, 12 is a timing extraction section, 13 is a frame synchronization detection section, 14 is an information separation section, 15 is a decoding section, 16 is the transmission control circuit, 1
7 is an encoding unit, 18 is a multiplexing processing unit, 19 is a receiver,
20 is a request instruction bit amplitude monitoring section, 21 is a control signal channel significant information detection section, 22 is an appable bit insertion section, and 23 is a collision state indication pit insertion section. Patent applicant: Nippon Telegraph and Telephone Public Corporation Patent attorney Mori 1) Jyo (A) Tsumugi 6r (B)

Claims (1)

[Claims] In a digital integrated service network, a digital service unit connected to a subscriber line, a digital bus having at least an uplink and a downlink connected to the digital service unit, and a receiver and a driver connected to the digital path, respectively. frames having a data signal channel and a control signal channel are transmitted and received on the uplink and downlink, respectively, and the plurality of terminals are provided with a plurality of terminals having a data signal channel and a control signal channel, respectively, on the uplink and the downlink. The terminals compete for occupation of the control signal channel, include on the downlink at least enough bits to indicate an appellation pull state and enough bits to indicate a collision state, and generate at least a request on the uplink frame. In addition to including bits sufficient to indicate the status, the digital service unit detects the occurrence of a collision condition regarding requests from multiple terminals based on the content of the previous uplink frame and the newly changed content of the frame. Based on the content of the previous downlink frame and the newly changed content of the frame, each terminal checks whether a collision has occurred regarding the request it issued, and determines whether the signal channel is occupied. The terminal requesting we transmits a pulse with a predetermined waveform at the time of request generation to the bit instructing request generation on the uplink frame, and the digital service unit detects the request generation state on the uplink frame. If the amplitude of the monitoring bit waveform is greater than the amplitude of the predetermined pulse, the digital service unit determines that a collision has occurred between multiple terminals, and the digital service unit determines that a collision has occurred between multiple terminals, The above requesting terminal monitors the bit indicating the collision state on the downlink frame, checks the collision state, and determines whether there is a collision regarding the request issued by itself. This in-home connection control method is characterized by checking whether or not an occurrence has occurred.