JPS63107296A - Line concentrating and line distributing system - Google Patents

Abstract

PURPOSE:To shorten time required for controlling a set call by providing a 1st mode to which a delay time is measured to control a signal transmission timing and a 2nd mode to which a call is set. CONSTITUTION:A line concentrating and line distributing terminal (MAU) specification signal ASG consists of a mode bit showing its mode, MAU addresses #1 and #2 and control information. The mode bit identifies the 1st mode to which the delay time is measured and a level is controlled and the 2nd mode to which a set call is controlled. When a call is requested, an MAU 2 receives the signal ASG that allows a call from a private branch exchange 1, and issues a call request response signal RSP. The MAU 2 and the private branch exchange recognize the call, and exchange information regarding the allocation of time slots with the aid of the signals ASG and RSP. Through the above- mentioned procedures, the MAU 2 transmits a call signal to an exchange, recognizes an originating sound that is returned from the exchange, and makes a call through a telephone set 5.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a line concentration distribution system in which a plurality of terminal devices are connected to a central unit via a line concentration distribution terminal.

(Conventional technology) Multiple terminal devices such as telephones are connected to a private branch exchange (PBX).
When configuring a network by connecting to
It takes a lot of effort to connect directly with X,
Furthermore, since each terminal device is often distributed and arranged in a plurality of buildings or a plurality of floors, there is a problem in that equipment costs are high.

Therefore, conventionally, a concentration distribution terminal to which multiple terminal devices are connected is installed in each building or each floor, and each concentration distribution terminal and the PBX, which is the central equipment, are connected to the uplink and downlink transmission paths (first A method has been considered in which the signals are coupled via a second transmission path (and a second transmission path) and the signal is transmitted in a time-division manner through these transmission paths.

If such a system is configured, it will be easy to install the backbone transmission line between the central equipment and the concentration distribution terminal, and the terminal equipment can be connected to the nearest concentration distribution terminal, making the network flexible. It becomes possible to construct.

However, in a system configured in this way, signals are transmitted between multiple concentration distribution terminals and the central equipment via a common transmission path, and each concentration distribution terminal is connected to each other on the transmission path. They are connected to different positions. For this reason, the transmission path length between each concentration distribution terminal and the central equipment differs for each concentration distribution terminal, and the difference in transmission delay time caused by the difference in transmission path length causes a difference in signal transmission time. There is a problem that occurs.

If signals are transmitted without considering the difference in these transmission delay times, a problem arises in that signal collisions occur on the transmission path.

In order to solve this problem, the inventors of the present invention previously proposed in Japanese Patent Application No. 59-268824 etc. that the transmission delay time between each concentrator and distribution terminal and the central equipment was calculated in advance, We proposed a method to control the timing of signal transmission from each concentrator/distributor terminal according to the transmission delay time. In this method, the central device sequentially sends a concentration distribution terminal designation signal to each concentration distribution terminal, and the concentration distribution terminal that receives this signal sends a response signal to the central device during a predetermined window frame period. . The concentrator and distribution terminal then receives the response signal returned from the central device, and uses the time from the sending timing of the response signal to its reception timing as the transmission delay time in the transmission path. measure. Based on the transmission delay time measured in this manner, the timing at which signals are sent from the concentration/distribution terminal to the central device is controlled.

However, in such a line concentration distribution system, the call setting control is realized by a polling method using a line concentration distribution terminal signal (hereinafter referred to as an ASG signal) and a response signal (hereinafter referred to as an R3P signal). Several hundred meters for setting control
It took 5ec to several SQC. For example, if the frame period is 500μ513e to 4m5ec, and if one ASG signal is sent to the terminal in one frame, then the number of terminal equipment (subscriber terminals) connected to each concentration distribution terminal is 1, If there are 000 pieces,
500m5ec~4s to set up a call for all terminals
It took a lot of time.

Therefore, if the above-mentioned control is performed, the system's response to off-hook will be poor, and the number of queues for call processing among multiple exchanges will increase, which will increase the processing burden (load) on the exchanges. occured.

(Problems to be Solved by the Invention) As described above, the line concentration distribution system using ASG signals and RSP signals has a problem in that the time required for call setup is too long.

The present invention has been made in consideration of these circumstances, and its purpose is to provide a line concentration distribution system that can shorten the time required for call setup control and improve system response. It's about doing.

[Structure of the Invention] (Means for Solving the Problems) The present invention provides a first mode for measuring delay time and controlling signal sending timing in a line concentration distribution system using ASG signals and R8P signals. and a second mode for setting up a call, and more specifically, a call request from a terminal is made by a contention method. It is.

(Function) According to the present invention, since a call request from a terminal is issued by a contention method, it is possible to significantly shorten the time required to set up the call. As a result, it becomes possible to sufficiently speed up the system's response to off-hook, and it also becomes possible to reduce the load on the exchange.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

Figure m1 schematically shows the basic transmission form of the ASG signal and RSP signal according to the embodiment method, and is T42.
3 and 3 show the above ASG signal and R9P signal, respectively.
FIG. 4 is a diagram showing an example of a signal configuration. FIG. 4 is a diagram showing a configuration of a signal transmission system to which the embodiment method is applied, and FIG. 5 is a diagram showing a frame configuration of a transmission signal.

As shown in FIG. 4, the signal transmission system to which this method is applied connects a central device 1 such as a private branch exchange and a plurality (n) of east line distribution terminals 2a, 2b, to 2n, to each concentration distribution terminal 2.
A first transmission line 3 for transmitting signals from a, 2b, ~2n to the central equipment 1; 2 are connected to each other via transmission lines 4, and a plurality of terminal devices 5 such as telephones are connected to the nearest concentration distribution terminal 2a, 2b,
~2n, respectively. Here, the plurality of line concentration distribution terminals 2a, 2b.

~2n are distributed and arranged in different buildings or on different floors. Note that the line concentration distribution terminal 2a.

When only a single terminal device 5 is connected to 2b, 2n, the line concentration distribution terminals 2a, 2b, 2n are arranged in each area.

The central device 1 transmits, for example, the fifth transmission line via the second transmission path 4.
With a frame structure as shown in Figure (a), transmission data Do to each concentration distribution terminal 2a, 2b, ~2n,
DO, ~Do are indicated by diagonal lines in the figure, 1111 12
12 In! The data is transmitted in a time-division manner with dummy data indicating n in between. Here, the above-mentioned line concentration distribution terminals 2a, 2b.

The subscript 1x of the transmission data Do for ~2n indicates the address of the line concentration distribution terminal, and the subscript lx indicates the data length. In addition, each line concentration distribution terminal 2a, 2b
, ~2!1 is transmitted via the first transmission line 3, for example, to the fifth
Each transmission data D1 has a frame structure as shown in Figure (b).
□111'D"1212' ~ DI in hours and minutes n
It is intended to be sent at a relatively low rate.

Note that the ASG signal in FIG. 5(a) indicates the concentration distribution terminal designation signal sent from the central device 1 to each concentration distribution terminal 2a, 2b, to 2n, and the R3 signal in FIG.
The P signal is sent to each line distribution terminal 2a in response to the ASG signal.
, 2b, ~~2n to the central device 1. This response signal (R5P signal) is transmitted back to itself via the second transmission path 4 during the window frame period.

As shown in FIG. 2, the line concentration distribution terminal designation signal ASG includes a mode pit indicating the mode, MAU address #1. 2, and control information. The above mode pit has a first mode for delay time/level control,
This is for distinguishing from the second mode for call setting control. These first and second modes are basically realized alternately every frame as illustrated in FIG.

Here, the delay time measurement/level control mode achieves two functions. One of them is the line concentration distribution terminal 2a
, 2b, to 2n and the central device. Another function is to measure the signal transmission delay time between each concentration distribution terminal 2a.
.

This is a function to control the signal transmission level from 2b and 2n. However, this latter level control function is not necessarily necessary in this method.

On the other hand, the call setup control mode is executed independently of the delay measurement in the delay measurement/level control mode to control call setup. Specifically, it is part of a series of procedures for setting up a path (communication path) between the terminal that made the call, the central unit 1, and the called terminal. be.

Now, the MAU address 1 in the ASG signal mentioned above is RS in the next frame for sending the ASG signal.
This specifies the address of the MAU to which the P signal should be sent. Here MAU is MediumAttachffl
It is an abbreviation for ENT Unit and is called a multi-function modem, but here it is the line concentration distribution terminal 2a.

2b, to 2n are shown. Also, MAU address lt2
specifies the address of the MAU that should receive the control information shown after this address li2.

The content of the control information differs depending on each of the above modes. That is, in the case of the delay time measurement/level control mode,
The control information is given as information on the amount of correction for delay time and level control. Further, in the case of the call setting control mode, the above control information is control information for call setting.

As described above, only the MAU at the address designated by the MAU address #2 receives the control information having different contents.

The ASG signal as described above is transmitted from the central device 1 via the second transmission line 4 for downlink to each concentration distribution terminal 2a, 2b,
~2n, respectively. In response to this, RSP signals are transmitted from each of the line concentration distribution terminals 2a, 2b, to 2n to the central device 1 via the first uplink transmission path 3.

As shown in FIG. 3, this R8P signal consists of a synchronization bit, a mode pit indicating the mode, an MAU address for identifying the transmission source concentration distribution terminal, and control information. This control information is an unmodulated signal in the delay time measurement/level control mode, and is given as information necessary for call setup, such as an ACK/NAK signal, only in the call setup control mode. It has become something that can be done.

In this line concentration distribution system, the ASG signal and R
The 9P signal is transmitted to the central device [and the plurality of line concentrators 2a] in a frame configuration as shown in FIG.

It is supposed to be sent and received between 2b and 2n,
Basically, the above delay time measurement/
The level control mode and the call setting control mode are alternately repeated.

To explain the delay time meter aIII/level control mode, in this mode, from the central device 1 to the ASG
Concentration and distribution terminal 2 that sends a signal and should measure the delay time and control the level at the MAU address 1 of this ASG signal
Specify a, 2b, ~2n. All line concentration distribution terminals 2
a, 2b, ~2n can receive signals transmitted from the central device 1 via the downlink transmission line 4, but each concentration distribution terminal 2a, 2b, ~2n monitors the MAU address answer 1, respectively. When the address matches its own address, the ASG signal is taken in. In other words, only the line concentration distribution terminal (MAU) designated by the MAU address $1 receives the ASG signal internally.

Then, in the next frame, the central device 1 transmits an ASG signal in call setup control mode.

During this frame period, an RSP signal is sent back to the central unit 1 from the designated line distribution terminal (MAU) as described above. In the case of the terminal 2 which does not measure the delay time at all, the transmission timing of this RSP signal is determined by using the window period shown in FIG.
Control is performed so that collisions of SP signals do not occur. In addition, if the delay time measurement has already been performed, the line concentration distribution terminal 2 knows the signal transmission timing at which the R3P signal that will cause a collision can be transmitted, and therefore the R3P signal is transmitted at that signal transmission timing. Send.

After that, delay time measurement using the ASG signal and RSP signal and control of the signal sending timing are performed only when finely adjusting the sending timing of the R3P signal. In addition, all the line concentration distribution terminals 2a, 2b, ~
After the delay time measurement for 2n is performed, each concentration distribution terminal 2a, 2b, to 2n is connected to R without any collision.
Since the respective timings at which the 3P signals can be transmitted are roughly known, there is no need to set a wide window period as described above.

At this time, it is sufficient to essentially add address information indicating the terminal to the R3P signal transmitted from each concentration distribution terminal 2a, 2b, ~2n, but here, delay time measurement/ A code indicating that it is an RSP signal in level control mode is added.

However, when such an RSP signal reaches the central device 1, the central device 1 determines a predetermined arrival time and deviation (correction amount) from the received signal level for the received RSP signal. The information is then carried in the ASG signal to be transmitted in the next frame. That is, the MAU of the ASG signal
The address of MAU1 is assigned to address #2, and the correction amount determined as described above is assigned as subsequent control information. The MAU address #1 at this time becomes the MAU that specifies the next line concentration distribution terminal.

1+1 The MAU 1 thus receives the above control information of the RSP signal returned from the central device l, adjusts and controls the signal transmission timing and the signal transmission level from the MAU, and controls the subsequent significant signal. Prepare for sending.

The above processing is repeatedly executed in order for all MAUs.

On the other hand, the call setup control mode is executed as follows. As shown in FIG. 1, in the next frame after the ASG signal in delay time measurement/level control mode is sent, the central device 1 sends out an ASG signal in call setup control mode. The mode pit described above in this ASG signal is a bit display corresponding to this call setting control mode. Also, at this time, for MAU address #1, for example, all of them are set to "1". Furthermore, in all the line concentration distribution terminals 2a, 2b, to 2n, when the MAU address answer 1 is "1", the R8P signal is transmitted from the terminal (MAU) requesting a call by the contention method.

Assuming that only one terminal (MAUR) has issued a call request, the M
AUR sends an RSP signal in call setup mode to central equipment l. This R5P signal does not contain any temporary control information, and is blank or dummy control information.

The central IF which receives such an R8P signal detects the MAU that issued the call request from the MAU address in the RSP signal. It should be noted here that there is no guarantee as to whether or not the R8P signal is received without collision, so it is necessary to confirm that it has been received without collision.

Therefore, the central device 1 selects A in the call setup mode of the next frame.
MAU address #1 in the SG signal
It is transmitted as R to the downstream transmission path 4. At this time, ASG
Slot allocation information may be included in the signal control information. This slot assignment information is stored in one terminal (MAU).
) in order to make effective use of limited frames by making the number of allocated slots variable.

Therefore, the ASG with the MAU address H as MAUR
The terminal (MAUR) that received the signal ACKs the control information in the RSP signal in call setup mode of the next frame.
Allocate a signal and send it. Then, the central device 1 confirms from the R8P signal including this ACK that there is no collision and that the call request is issued from only one terminal MAUR. After that, the center bag fil is ASG
Communication with the line concentration distribution terminal MAUR is started via the time slot assigned by the signal.

On the other hand, if a call request is issued to each of a plurality of line concentration distribution terminals in response to the ASG signal in the call setting mode described above, each of these terminals sends an R8P signal. These RSP signals are received by the central device 1 while colliding with each other on the upstream transmission line 3. As a result, the central unit l receives an R3P signal that is erroneous due to the collision.

However, as mentioned above, central bag i 1 cannot know whether or not the received RSP signal is erroneous due to collision, so it transmits, for example, the data MAUx indicated by the MAU address of the received R3P signal in the next frame. It is inserted as is into MAU address #1 of the ASG signal and transmitted.

Then, although the terminal MAUX indicated by the address MAUX receives the ASG signal, it returns a NAK to the central device 1 as control information since no call request has occurred. Alternatively, since the terminal indicated by address MAUx does not exist, neither ACK nor NAK will be returned as control information for the RSP signal of the next frame.

If the central device 1 receives a NAK in this way, or if neither an ACK nor a NAK is received within a predetermined period of time, the central device 1 receives the above-mentioned reception because there was no call originating from the MAUx indicated by the previously detected address. It is recognized that the RSP signal was erroneous due to collision.

Here, A with MAU address #1 of “1” is sent from central device 1.
If the SG signal is transmitted again, RSP signals will be transmitted simultaneously from the plurality of line distribution terminals having the above-mentioned call request, and a collision will occur in the same way.In order to avoid re-collision, the central device 1 R3P signals for call setup are randomly sent to the line concentration distribution terminals.

That is, the central device 1 connects each line concentration distribution terminal 2a, 2b, to 2
A predetermined ASG signal is transmitted in order to make the transmission timing of the R8P signal from n different from each other. Each of the line concentration and distribution terminals 2a, 2 which received such a predetermined ASG signal
Random numbers are generated in each of b and 2n, and the sending timing (frame) of the RSP signal is adjusted individually according to the random numbers. Specifically, each of the line concentration distribution terminals 2a, 2b, to 2n generates a random number using a known means, and calculates the random number using mod 5. Then, each frame in which the R8P signal is sent is delayed by the calculated value. In addition, the above mod
As will be explained later, in calculation 5, when the probability of call requests colliding is not very high, most of the collisions can be avoided by adjusting the transmission timing of the R8P signal within a range of 5 frames. Depends on what you can do.

By controlling the call setup in this way using the function system, it is possible to notify the central device 1 of a call request from the line concentration distribution terminal reliably and in a short time.

When the call request is notified to the central unit 1, the address of the MAU that requested the call request is inserted into MAU address #2 in the ASG signal in the call setup mode of the next frame, and the time slot for that MAU is inserted. The allocation will be made. Thereafter, a communication path between the calling terminal and the called terminal is established by transmitting and receiving control information, etc. via the D channel for which time slots are set, and communication between them is started.

Note that if a collision occurs between RSP signals that have not undergone level adjustment, the address of one MAU may be correctly received because the level difference between those signals is large. In this case, the central unit 1 performs the above-described call confirmation procedure for the MAU at the address where the reception was detected.

When the call is confirmed from the MAU, the AC
When K is returned, control of the call setup ends.

At this time, since the ASG signal confirming the call is not sent to the terminal that was ignored due to the above collision, the ASG signal for the next call setup mode is sent to that terminal, and the call request is queried by the contention method. You will have to wait until then. It should be noted that if there is no line concentration distribution terminal with a call request at the time of scheduling a call request using this contention method, the ASG signal whose MAU address #2 is 1'' at that time is ignored.

The time required to control call setup using the contention method described above will now be considered. In the embodiment described above, 2
An ASG signal in call setup mode is transmitted once per frame. Therefore, each line concentration distribution terminal 2a,
2b, to 2n, a call request is issued from a terminal 5 such as a telephone connected thereto, and after an average of one frame, a call request is issued from the concentration distribution terminal 2 to the central unit 1. Become. Thereafter, a time slot is assigned to the line concentration distribution terminal 2 by the ASG signal in the call setup mode two frames later, and the call setup control is completed. Therefore, the period of the frame mentioned above is 125 μsec.
c, approximately 400 μs after the call request occurs.
Control of the call setup will be completed after ea.

In addition, each concentration distribution terminal 2a, 2b, ~2n and the central device 1
ASG signal and R5 at the above-mentioned frame period between
Even when transmitting P signals, each concentration distribution terminal 2a
, 2b, to 2n, call requests from the terminal devices 5 connected thereto may be frame multiplexed and transmitted.

Frame multiplexing of call requests conversely means that the number of output ports for call requests is reduced; for example, in the case of four frame multiplexing, the actual frame period is 500 μsec. In this case, the call setting control described above is approximately 1,5f
It will end after flsec. In addition, in the case of 32-frame multiplexing, the actual frame period is 4ffl.
sec, and the call setup control ends after about 12m5ec. Therefore, compared to call setting control using polling, the processing time can be significantly shortened.

Note that when the above-described frame multiplexing is performed, it is undeniable that the bit length of the data to be sent out each time becomes long, and there is a concern that the delay may be a problem. However, in the case of audio, a delay of about 5a+sec due to multiplexing is allowed, so
Even in the case of multiplexing two frames, the delay is about 4m5ec, so no problem occurs.

On the other hand, it is assumed that one telephone 5 is connected to each of the line concentration and distribution terminals 2a, 2b, to 2n, and the line concentration and distribution terminals 2a, 2b, .
Assuming that the number of terminals a, 2b, ~2n is 500, and the call rate occurring at each concentrator/distribution terminal 2a, 2b, ~2n is 0.15 erlangs, two or more call setups occur during the above-mentioned frame period of 4m5ec. The probability that a request will occur is (3X 10
”-6). This value means that even if call setup is controlled using the contention method described above, the probability that a collision will occur is extremely low. In other words, if a collision occurs, call setup control will be delayed. This means that there is almost no possibility that the time will become extremely long.Therefore, the contention method allows call setup to be controlled efficiently in a short time.

FIG. 6 is a diagram showing a call connection control procedure in a communication system in which call setting control is performed using the contention method described above. In FIG. 6, ■ indicates the ASG signal and RSP signal in the control time slot, and ■ indicates the control data (D channel) in the audio time slot.
, ■ indicate audio data (B channel) in the audio time slot.

To briefly explain the control procedure shown in FIG. 6,
When a call request occurs due to the telephone going off-hook, the MA
Upon receiving the ASG signal from the central device 1 for permission to make a call, U issues an R5P signal for requesting a call. The central device 1 detects a call request based on this R5P signal. And M A 'U
and the central device to confirm the call 2. The ASG signal and the RSP signal are used to transmit a response to the call confirmation, time slot allocation, time slot allocation confirmation, time slot use permission, and time slot use permission. to exchange information mutually.

After the above procedure, the MAU sends a calling signal to the exchange TD using the allocated time slot. Then, when the user confirms the dial tone returned from the exchange and dials from the telephone, a selection signal consisting of a dial pulse or a PB double signal is transmitted from the MAU to the exchange. Upon receiving this selection signal, the exchange sends a ringing signal to the central equipment 1 of the communication partner, and at the same time returns a ringing tone (RBT) to the telephone of the calling party.

At this time, based on the test results of the line condition detected during the delay time measurement periodically performed by the central equipment 1, the exchange determines whether the line condition of the called side is poor or the line condition of the calling side is poor. A busy tone is sent back to the telephone.

The central equipment 1 of the communicating party, which receives the calling signal from the exchange TD, detects this as a telephone call and allocates a time slot to the MAU that accommodates the dialed telephone and requests permission to use the time slot. Carry out procedures. This procedure is also performed using the ASG signal and RSP signal described above. When the time slot is established, a ringing signal (RG) from the exchange is sent to the dialed telephone via the MAU. When the dialed telephone goes off-hook in response to this ringing tone, that information is transmitted to the exchange as a response signal, and the ringing to the above-mentioned calling telephone is stopped.

Through the above procedure, a communication path between the calling telephone and the receiving telephone is established via each of the above-mentioned time slots, and a telephone conversation is started.

Note that the call termination procedure is started when one of the telephones goes on-hook, and a disconnection signal is notified to the exchange. In response to this disconnection signal, the exchange gives a call termination signal to the other telephone, and when the telephone goes on-hook, a disconnection signal is given to the exchange.

The exchange detects the end of the call by inputting the disconnection signal, issues a request to release the set time slot as described above, and releases the time slot after obtaining the confirmation information.

This time slot release procedure is also performed using the above-mentioned ASG signal and R3P signal.

The above is the general call connection control procedure in this system.

By the way, in the above explanation, when a collision of calls from a plurality of MAUs occurs, in order to confirm this, a call confirmation request is issued to the MAU at the address where reception is detected.

However, as shown in FIG. 7, collision of calls from multiple MAUs may be determined by checking the CRC at that time. When a collision is detected by the CRC check, the above-mentioned ASG
A signal is used to instruct backoff, and each concentration distribution terminal generates a random number for confirming backoff.

Then, after a predetermined backoff for the subsequent call authorization, each MAU may issue a new call.

Note that even if a collision occurs again after a predetermined backoff, backoff may be performed in the same manner. In this way, compared to the collision confirmation described in the previous embodiment, collision detection can be performed more simply and effectively, and countermeasures can be taken promptly.

By the way, in the embodiment described above, the first mode for delay time measurement/level control by polling and the second mode for call setting control by contention are alternately implemented.

However, once the delay time measurement/level control by polling has been implemented for all the line concentration distribution terminals 2a, 2b, to 2n, only correction control is required, so there is no need to perform constant control. It can be said that there is not much.

Therefore, for example, if the aforementioned collision occurs in the second mode using the contention method as shown in FIG. It is also possible to allocate it to the second mode.

That is, when a collision of call requests due to contention occurs as shown in FIG. 8, and this is detected by the above-mentioned CRC check, the frame used in the polling mode is converted into an ASG signal and an R5P signal based on the new contention method. Used in control mode for call setup using In other words, two modes for call setup control are set, and call setup control information such as a call request is transmitted and received in both modes. When a call connection is completed in either mode, the other mode of call setting control is continued as is, and the mode in which the call connection was completed is returned to the delay time measurement/level control mode using polling described above. Make it.

In this way, in combination with the above-mentioned collision avoidance by backoff, it becomes possible to complete the call connection in a short time. In other words, it is possible to increase the chances of receiving a re-call and complete control of the call connection faster. In addition, while controlling a call connection in one polling mode, it is possible to control another call connection in the other polling mode, so it is possible to handle multiple call requests that conflict with each other. It becomes possible to deal with each effectively and accept the call request.

Furthermore, if a call is not detected within a predetermined period of time, such as the maximum number of waiting frames for backoff, it is possible to automatically return to the original mode of alternating contention and polling. Good.

In addition, if the above-mentioned continuous tension mode occurs more frequently than a predetermined value, for example, 3 in 50 frames.
If this occurs more than once, the mode for call connection control in the contention mode, which is performed alternately as described above, and the mode for delay time measurement/level control performed by polling, are used in a steady state. It is also possible to change the ratio. For example, if the above-mentioned constant ratio of polling and contention is set to (1:2), more call requests can be accepted without collisions, or if collisions still occur frequently. The above ratio may be changed to (L:8).

In this way, if the ratio of contention mode in the steady system operation state is increased, for example, if the connected terminal 5 is a data terminal of 15DN and the B channel is
It is possible to increase the number of opportunities for call connection control by accepting call requests that increase in frequency at one time, such as when performing D-channel packet communication, and it is also possible to reduce the frequency of collisions. becomes.

In addition, when the frequency of collisions is low, the steady ratio of polling and contention described above is set as (2:l),
(4:l), (8:l) may be changed.

In this way, if the frequency of delay time measurement/level control by polling is increased when there are few call requests, more accurate control of signal transmission timing and transmission signal level will be possible, resulting in highly reliable communication. It becomes possible to do so.

Although the embodiments of the present invention have been described above, the system of the present invention is not limited to these embodiments. For example, in the delay time measurement/level control mode using polling, processing up to call setup may be performed as in the conventional method. Further, the number of terminal devices 5 connected to each of the line concentration distribution terminals 2a, 2b, . Furthermore, the form of the transmission path 3.4 may be set by frequency multiplexing a single carrier path, or different carrier paths may be used. Also, the signal transmission format is 4-phase PS.
K etc. can be adopted as appropriate.

Furthermore, the measurement of delay time and the transmission signal level may be performed at the individual line concentration distribution terminals 2a, 2b, to 2n. In addition, the present invention can be implemented with various modifications without departing from the gist thereof.

[Effects of the Invention] As explained above, according to the present invention, although it is a line concentration distribution method that controls signal transmission timing by measuring delay time, it is possible to significantly shorten the time required for call setup, and Great practical effects can be achieved, such as being able to effectively deal with call collisions and performing efficient call connection control.

[Brief explanation of the drawing]

FIG. 1 is a diagram schematically showing the operation modes of delay time measurement/level control by polling and call connection control by contention, which is an embodiment of the present invention.
FIG. 3 is a diagram showing the configuration of the R8P signal, FIG. 4 is a schematic configuration diagram of a communication system to which the present invention is applied, and FIG. 5 is a diagram showing the configuration of the R8P signal. Figure 6 shows the frame structure of the ASG signal and R3P signal transmitted in a time-division manner, Figure 6 shows the general call connection control procedure using this method, Figure 7 shows the call connection when a call collision occurs. FIG. 8, which is a diagram showing a connection control procedure, is a diagram schematically showing operation modes of delay time measurement/level control using polling and call connection control using contention in another embodiment of the system of the present invention. DESCRIPTION OF SYMBOLS 1...Central unit, 2a, 2b, ~2n...Aggregation distribution terminal (MAU), 3...Uplink transmission line, 4...
- Downlink transmission line, 5...terminal equipment (telephone). (a) (b) Figure 7

Claims (8)

[Claims] (1) Time-divisionally transmitting signals from a plurality of line concentration distribution terminals to a central device via a first transmission path, and time-divisionally transmitting signals from the central device to the plurality of line concentration and distribution terminals via a second transmission path. In a line concentration and distribution method, the delay time in signal transmission on the first and second transmission paths is measured when transmitting a signal, and the timing of signal transmission from the line concentration and distribution terminal is controlled based on the measurement result, A line concentration distribution system comprising a first mode in which the control is performed by measuring the delay time, and a second mode in which control related to call setting is performed. (2) The line concentration distribution system according to claim 1, wherein the first and second modes are executed at a predetermined ratio. (3) The central device is provided with means for knowing the traffic of call connection requests, and variably controls the proportions of the first and second modes according to this traffic.
Concentration distribution method described in section. (4) The line concentration distribution system according to claim 3, wherein the traffic of call connection requests is detected from collisions of call connection requests. (5) The line concentration distribution system according to claim 4, wherein collision of call connection requests is detected from a CRC error. (6) In the second mode, the line concentration and distribution method according to any one of claims 1 to 5, wherein a call request is issued from the line concentration and distribution terminal to the central device by a contention method. . (7) The line concentration distribution system according to claim 6, wherein the call request is a signal sent in response to a specific signal from the central device. (8) In the first mode, a level control signal is transmitted to control the transmission level at each concentration distribution terminal so that the level of the signal received at the central device is a constant value. A line concentration distribution system according to any one of claims 1 to 5.