JPH0732394B2 - Concentration distribution method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Field of Industrial Application) The present invention relates to a concentrating distribution system in which a plurality of terminal devices are connected to a central apparatus via a concentrating distribution terminal, and in particular, each concentrating distribution The present invention relates to a concentrating distribution method for setting a subframe as a transmission path of a transmission line between a terminal and a central device in response to a call setting request.

(Prior art) When a plurality of terminal devices such as telephones are connected to a private branch exchange (PBX) to form a network, each terminal device and PB
There is a problem in that a large amount of labor is required to connect the X and the wiring directly, and the facility cost is high. This is because each terminal device is often distributed and arranged in a plurality of buildings or a plurality of floors.

Therefore, in the past, a concentration distribution terminal was installed with multiple terminal devices connected to each building or floor, and each concentration distribution terminal and PBX, which is the central unit, were connected via transmission lines for uplink and downlink. However, a method of performing signal transmission in a time division manner through these transmission lines has been considered. By constructing such a system, it is easy to install the central device and the concentration distribution terminal, which are the backbone, and it is possible to connect the terminal equipment to the concentration distribution terminal located closest to the system. Is possible.

However, in this system, the frame structure for time-division signal transmission between each concentration distribution terminal and the central device is such that subframes are fixedly allocated, and information is transmitted between the concentration distribution terminal and the central device. Even if the transmission is not necessary, the corresponding subframe is blocked, so that there is a problem that the transmission path cannot be used efficiently.

Further, in this system, signal transmission is performed between a plurality of concentration distribution terminals and a central device via a common transmission line, and each concentration distribution terminal is connected to a different position of the transmission line. For this reason, the transmission line length between each concentration distribution terminal and the central unit differs depending on the concentration distribution terminal, and the difference in transmission delay time due to the difference in transmission line length causes a difference in signal transmission time. If signal transmission is performed without considering this difference in transmission delay time, signal collision on the transmission path is caused.

In order to solve this point, the present inventors first sent the centralized distribution terminal designating signal from the central apparatus to each centralized distribution terminal in order, and the centralized distribution terminal receiving this signal sent the signal during the predetermined window frame period. After sending the response signal to the central device, the response signal sent back from the central device is received, and the time from the sending of the response signal to the receiving of the response signal is obtained as the transmission delay time at each concentration distribution terminal, and these transmissions are performed. We proposed a concentrating distribution method that adjusts the signal transmission timing from the concentrating distribution terminal based on the delay time (Japanese Patent Application No. 59-268824).

However, in this method, the time occupied by the window frame for measuring the transmission delay time within one frame cannot be ignored, and this also causes a decrease in the utilization efficiency of the transmission path.

(Problems to be Solved by the Invention) As described above, in the conventional concentration distribution system, subframes corresponding to each concentration distribution terminal are fixedly assembled in a time division manner,
Further, since the window frame for measuring the transmission delay time is also fixed, there is a problem that the utilization efficiency of the transmission path is low.

The present invention has been made in view of the above problems of the prior art, and an object of the present invention is to provide a concentrating distribution system in which the utilization efficiency of a transmission line is improved.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve this object, the present invention performs time-division signal transmission from a plurality of concentration distribution terminals to a central device via a first transmission path. In a concentrating distribution method in which signals are transmitted from the central device to a plurality of concentrating distribution terminals in a time division manner via a second transmission line, in the concentrating distribution system from the central device to the plurality of concentrating distribution terminals via the second transmission line. One of the signals transmitted to
A fixed length configuration in which a frame is time-division-multiplexed with a plurality of subframes, a concentrating distribution terminal designating signal for commonly controlling signal transmission by these subframes, and a window frame for measuring a transmission delay time. At the same time, one frame of the signal transmitted in a time division manner from the plurality of concentrating distribution terminals to the central device via the first transmission path is used to measure a plurality of subframes and a transmission delay time. The window frame and the window frame are time-division multiplexed to have a fixed length.

Then, the central device, when requesting the call setting to the plurality of concentration distribution terminal, in the concentration distribution terminal signal, a call setting control signal, and the address of the destination distribution line concentration distribution terminal,
The subframe number to be used and the subframe length are inserted and transmitted, and the plurality of concentration distribution terminals,
The first transmission is performed based on the subframe number and the subframe length included in the centralized distribution terminal designation signal coming from the central device, and the round trip transmission delay time measured by the first and second transmission paths measured in advance. The transmission timing of the subframe to be sent to the road is controlled.

(Operation) In the present invention, when the frame structure for time-division signal transmission between the concentration distribution terminal and the central unit receives the call setting control signal, that is, when it is necessary to transmit information between them. Only subframes are assigned, and there are no unused subframes.

Further, according to the present invention, one concentrating / distributing terminal designating signal is transmitted per frame, and a plurality of subframes of the subsequent frame are controlled by the one concentrating / distributing terminal designating signal. Therefore, the transmission capacity of the concentrated distribution terminal designating signal in one frame can be significantly reduced compared to the case where a dedicated concentrated distribution terminal designating signal is transmitted corresponding to each of a plurality of subframes. Since it is possible to increase the number of frames, it is possible to further improve the transmission efficiency.

Furthermore, according to the present invention, since the subframe length can be changed according to the amount of signal transmission, it is possible to interchange subframes among a plurality of terminals according to the amount of transmission, which allows As compared with the case where the subframe length is fixed, the subframe can be used efficiently without waste.

(Example) Hereinafter, the Example of this invention is described.

FIG. 1 is a schematic configuration diagram of a signal transmission system to which a concentration distribution system according to an embodiment of the present invention is applied, including a central device 1 such as a private branch exchange and a plurality (n) of concentration distribution terminals 2a to 2n.
A first transmission line 3 for transmitting signals from the centralized line distribution terminals 2a to 2n to the central device 1, and the central line device 1 to the centralized line distribution terminals 2a to 2n.
It is composed of a second transmission line 4 for signal transmission to 2n and a terminal device 5 such as a telephone connected to each concentration distribution terminal 2. It goes without saying that the terminal device 5 is connected to the nearest line distribution terminal.

The central unit 1 has, for example, as shown in FIG. 2 (a) a frame structure of a transmission signal from the central unit 1, the central line distribution terminals 2a ...
Transmission data DOi1 l1, DOi2 l2, ... DOin ln for 2n are time-divided with dummy data (indicated by diagonal lines) between the second transmission lines 4
Send to. ix represents the address of the concentration distribution terminal, and lx represents the data length. On the other hand, the line-concentration distribution terminals 2a to 2n similarly transmit the transmission data DIi1 l1, DIi2 l2, ... DIin ln by time division with the dummy data sandwiched between them, as shown in the frame structure of the transmission signal in FIG. 2 (b). 1 to the transmission line 3.

The ASG signal in FIG. 2 (a) shows the concentration distribution terminal designation signal transmitted from the central unit 1 to each of the concentration distribution terminal 2a to 2n, and the RSP signal in FIG. 2 (b) corresponds to this concentration distribution terminal signal ASG. Correspondingly, it is a response signal transmitted from each of the concentration distribution terminals 2a to 2n to the central unit 1 and itself for measuring the transmission delay time.

As shown in FIG. 3, the concentration distribution terminal designating signal ASG indicates whether or not the call concentration between the concentration distribution terminals 2a to 2n and the central unit 1 is necessary. 2a, 2b, ..., 2n in order to measure transmission delay time in
It is sent for each frame. That is, the addresses of the concentration distribution terminals 2a to 2n are sequentially assigned to the concentration distribution terminal addresses in the concentration distribution terminal designation signal ASG. When it is not necessary to set up a call with the line concentrating / distributing terminals 2a to 2n, all data below the call setting / termination control signal of the line concentrating / distributing terminal designating signal ASG is set to "0". Also, the line concentrating / distributing terminal which has received this line concentrating / distributing terminal designating signal ASG sets all the data below the call setting / termination control signal to “0” if there is no call setting request, and only its own line concentrating / distributing terminal address is transmitted to the central unit. 1 and send to itself and measure the transmission delay time. On the other hand, the central unit 1 judges that there is no call setting request from the line concentrating / distributing terminal and does not perform new processing.

When the central unit 1 wants to request a call setup to any of the concentration distribution terminals 2a to 2n, that is, when a call is requested from a terminal device to a terminal device connected to the concentration distribution terminal, The call setup / termination control signal in the distribution terminal designation signal ASG is set to "call setup", the number of the subframe to be used (the number indicating the number of the subframe from the frame start) is designated, and at the same time, the subframe is also designated. A terminal address for designating a terminal device connected to the line concentrating / distributing terminal to be called is designated. Then, the concentration distribution terminal that has received the concentration distribution terminal designation signal ASG measures a subframe for data transmission with the central device 1 thereafter, by measuring a predetermined subframe number and subframe length, and a transmission delay time. Preparations are made for sending data at the sending timing determined by, and the data sending is executed from the next frame onward.

Here, the "subframe length" is information that specifies the length of the subframe that the concentration distribution terminal wants to use for communication, that is, the capacity of the subframe (time slot), and the central unit 1 performs the exchange control based on this. Will be done.

When a call termination request is issued from the centralized distribution terminal connected to the terminal device of the calling source to the central device 1, when the central device 1 sends the centralized distribution terminal designating signal ASG to the centralized distribution terminal, The call setup / termination control signal is set to "call termination", and the subsequent transmission of the subframe is stopped. On the contrary, when a call or a call termination request is issued from the terminal device connected to the line concentrating / distributing terminal, a call setting / termination control signal in the response signal RSP from the line concentrating / distributing terminal, the subframe length, the calling terminal The address is set to the specified content,
After receiving the response signal RSP, the central unit 1 performs a predetermined action, and then sends a line distribution terminal designating signal ASG to the line distribution terminal to notify the subframe number and the like.

Further, when the plurality of subframes are transmitted, when one of them is deleted when the call is ended, the concentrated distribution terminal designating signal ASG indicates that another subframe following the deleted subframe is transmitted. It is also used to shift forward by the length of the deleted subframe. That is, by resetting the subframe number in the concentrated distribution terminal designating signal ASG, the applicable concentrated distribution terminals shift the transmission timing of the subframes simultaneously after the next frame.

The concentration distribution terminal designation signal ASG and the response signal RSP are
The format does not necessarily have to be as shown in FIGS. 3 and 4. For example, the concentrating / distributing terminal designation signal ASG is only the concentrating / distributing terminal address, the call setting control signal and the subframe number, and the response signal RSP is the call setting. Each may be configured only with a control signal, and other information may be transmitted via a call setting control subframe.

5 and 6 show specific configuration examples of the central unit 1 and the concentration distribution terminal. Further, FIG. 7 shows a timing chart for measuring the transmission delay time.

That is, in the central device 1, as shown in FIG.
The signal transmitted from the concentration distribution terminal (any of 2a to 2n) via the first transmission line 3 is passed through a bandpass filter (BP
F) 11 is received and is amplified to a predetermined level by the amplifier 12. The output signal of the amplifier 12 is demodulated by the demodulator 13 and then given to the exchange 15 via the concentrating distribution circuit 14. The concentrator / distribution circuit 14 uses, for example, a PCM voice signal if the exchange 15 exchanges the voice signal as a PCM code.
The control data signal is converted into a highway input format, and a control data signal transmitted from the terminal device 5 or the like separately from the voice signal is converted into a data highway format and given to the exchange 15. In this way, the voice signal and the control data signal which have been exchange-serviced by the exchange 15 are assembled and output by the concentrator / distribution circuit 14 in the signal form of the frame structure described above.

The data output from the exchange 15 via the line concentrating / distributing circuit 14 is modulated by a modulator 16 and then input to an adder 20 via a switch circuit 17, a read amplifier 18 and a BPF 19, which will be described later, and a pilot signal generator. It is superposed on a pilot signal of a predetermined frequency output from 21 and sent to the first transmission line 3. The pilot signal is always transmitted to the first transmission line 3 regardless of the presence or absence of data transmitted from the exchange 15. Further, the switch circuit 17, under the control of the window control circuit 22, blocks the input from the modulator 16 in the window frame period, and instead selects the output signal of the amplifier 12 and uses it as it is for the second transmission line. It sends it back to 4. By this window control, the response signal RSP sent from the concentration distribution terminal 2 via the first transmission line 3 is sent to the second transmission line 4.

Here, the control circuit 23 is added according to the present invention, and has a map of the frame structure shown in FIG. 2 (a), and the frame structure changes momentarily in conjunction with the operation of the exchange 15. To generate and generate the line-concentration distribution terminal designating signal ASG to each line-concentration distribution terminal 2. It should be noted that if the switching system 15 is of a blocking type in which the transmission path between the central unit 1 and the line concentrating / distributing terminal 2 is set up only when it is necessary to transmit information, the storage program of the switching system 15 is only slightly changed. It is possible to realize the function of the control circuit 23, and when the exchange 15 is a non-blocking system, the function of the control circuit 23 can be realized by using a microcomputer or the like.

In addition, each part of the central device 1 is a pilot signal generator.
It is controlled according to the clock CP generated from 21.

On the other hand, in the concentration distribution terminal 2, as shown in FIG.
The signal transmitted from the central unit 1 via the second transmission line 4 is received via the amplifier 31 and input to the BPFs 32 and 33. The BPF 32 separates and extracts the data component in the received signal from other signal components, and its output is guided to the demodulator 34 and demodulated / reproduced. The output of the demodulator 34 is input to the frame decomposing circuit 35, where the data (subframe DOix lx) transmitted to itself is extracted, and the data is connected to the concentrating / distributing terminal 2 terminal equipment. The frame is decomposed corresponding to 5. The transmission data to each terminal device 5 decomposed into frames is the interface circuit 36.
Is given to each terminal device 5 via.

The BPF 33 separates and extracts the pilot signal constantly transmitted from the central unit 1 via the second transmission line 4. A clock regenerating circuit incorporated in a delay measuring circuit 37, which will be described later, regenerates the clock CP from the pilot signal, and each unit in the line concentrating / distributing terminal 2 operates according to the clock CP.

Transmission data input from each terminal device 5 via the interface circuit 36 is input to the frame assembly circuit 38,
It is assembled into the sub-frame DIix lx according to a predetermined rule. After this signal (subframe) is modulated by the modulator 39, the transmission timing is controlled under the control of the delay measuring circuit 37 and is transmitted to the second transmission line 3 via the BPF 40 and the amplifier 41.

The delay measuring circuit 37 operates in synchronization with the clock signal extracted from the pilot signal, and is generated by the control circuit 42 when the line concentrating / distributing terminal designating signal ASG from the central unit 1 is detected via the demodulator 34. The transmitted response signal RSP is transmitted to the first transmission line 3 via the modulator 38, and from the transmission timing, the response signal RSP is returned from the central unit 1 via the second transmission line 4. Time is measured as the transmission delay time. Then, based on the measured transmission delay time, the control information of the signal transmission timing from the line concentrating distribution terminal 2 is obtained as described later. According to this control information,
The transmission timing of the data output from the concentration distribution terminal 2 via the modulator 39 is controlled.

Further, the control circuit 42 is provided according to the present invention, and receives the concentrating / distributing terminal designating signal ASG from the central unit 1 to control the subframe sending timing, the subframe length, etc., and the terminal device 5 A response signal RSP is generated in response to the calling request and the call termination request from and is supplied to the delay measuring circuit 37.

Next, the measurement of the transmission delay time and the signal transmission timing control based on the measured transmission delay time in this embodiment will be specifically described.

First, the following conditions must be satisfied for the window frame period tw necessary for measuring the transmission delay time. Now, the transmission delay time (maximum transmission delay time) from the central device 1 to the concentrating distribution terminal connected to the farthest position is td.
max, td min is the transmission delay time (minimum transmission delay time) to the line concentrator / distributor connected to the central device 1
(≈0) Then, at the beginning of the window frame period tw, the response signal RSP having the time width tp is transmitted from the concentration distribution terminal 2.

Now, as shown in FIG. 7 (a), when the central apparatus 1 sends out the concentrating / distributing terminal designating signal ASG and enters the window frame period tw, the signal ASG is the first in the concentrating / distributing terminal farthest from the central apparatus 1. Transmission delay time t via the transmission line 4 of 2
After the elapse of dmax, as shown in FIG.
Will be received at. Concentration distribution terminal 2 receives response signal RS with time width tp
When P is transmitted as shown in FIG. 7 (c), the response signal R
After the delay time t umax passes through the first transmission line 3,
Reach the central unit 1. Therefore, in order for the central unit 1 to send back the response signal RSP without causing a collision, the window frame period tw has the two transmission delay times t dmax, t umax and the time width tp of the response signal RSP. It is necessary to secure more than the added time range. In order to reliably detect the response signal RSP sent back from the central unit 1 at the concentrating / distributing terminal 2, the response signal RSP is transmitted after the transmission delay time t dmax, as shown in FIG. 7 (d). Since it reaches the distribution terminal 2, it is necessary to set the window frame period tw in the concentrating distribution terminal 2 to be longer than the above-mentioned period. That is, if the window frame period tw is set to tw ≧ t dmax + t umax + tp, the transmission delay time with the concentration distribution terminal 2 can be reliably detected in the window frame period tw regardless of the distance from the central device 1. It will be possible. Where (t
dmax + t umax) is the time until the response signal RSP sent from the line concentrating / distributing terminal 2 returns to the line concentrating / distributing terminal 2, and can be said to be a total transmission delay time. In addition,
When the transmission delay time is zero, the response signal RSP is transmitted as shown by the broken line in FIG. 7, so that the transmission delay time can also be measured within the window frame period tw. .

Now, assuming that the time slot given to the concentration distribution terminal 2i (i = 1, 2, ..., N) is the i-th time, for example, time t = 0.
Of the data frames sent from the central unit 1, the subframes addressed to the concentration distribution terminal 2i are time tdi + (i-, where Δ is the time length of each subframe, as shown in FIG.
1) After Δ has passed, the line distribution terminal 2i receives the line.

On the other hand, after one frame period T from time t = 0, that is, from time t = t, the central unit 1 receives the signal from each concentrating / distributing terminal 2, and the concentrating / distributing terminal has the above-described frame structure.
In order to receive the signal from 2i at the timing of T + (i−1) Δ, the line concentrating / distributing terminal 2i receives the time t ui prior to this, that is, at time T + (i−1) Δ−t ui. It is necessary to start sending signals. This means that the line concentrating / distributing terminal 2i has only to send a signal at the timing T + (i-1) Δ-t ui after receiving the signal addressed to itself at the time t di + (i-1) Δ. Means Therefore, as shown in the eighth time, the time Twait = {T + (i−1) Δ−t ui} − {t di + (i−1) Δ} = T− (t ui + t di) from the reception timing of the signal addressed to itself. If the signal is transmitted after waiting for, the arrival timing of the signal to the central unit 1 can be accurately determined and the collision of the signal on the first transmission line 3 can be prevented.

If the transmission delay time measurement as described above and the control of the signal transmission timing from the concentration distribution terminal 2 to the first transmission path 3 based on the measurement are performed, the concentration distribution terminal is not burdened with an excessive load. It is possible to optimally set the signal transmission timing from No. 2. Further, since each line concentrating / distributing terminal 2 measures the transmission delay time according to its own clock, the measurement accuracy can be made high, so that a time margin more than necessary for the signal transmitting timing from the line concentrating / distributing terminal 2 can be obtained. The feature of the present invention is that the collision of signals on the transmission line can be surely prevented without providing the transmission line, and the transmission line can be effectively used by assembling the subframe only when the information transmission is required. It will be demonstrated to the maximum.

Next, another embodiment of the present invention will be described. FIG. 9 shows the internal configuration of the concentration distribution terminal 2 in this embodiment.
As in the case of FIG. 6, the signal transmitted from the central unit 1 via the second transmission line 4 is received via the amplifier 51, and the data components and pilot signals in the received signals are respectively received by the BPFs 52 and 53. The separated and extracted data components are input to the carrier detector 54 and the demodulator 55, and the pilot signal is input to the controller 56. A carrier display signal, a reception clock, and demodulated reception data are supplied from the controller 56 to the frame decomposition circuit 57. As a result, the frame decomposing circuit 57 extracts the data of the sub-frame addressed to itself, and the frame decomposing circuit 57 decomposes the frame into the respective terminal devices 5 connected via the interface circuit 59 and sends the frame data.

The transmission data from the terminal device 5 is the interface circuit.
It is input to the frame assembling circuit 58 via 36 and assembled into a sub-frame. Frame assembly circuit 58 is a controller
Receives the transmission clock, transmission data transmission request, and response signal transmission request signals from 56, and transmits the transmission data and response signal RSP.
Is transmitted to the modulator 60 at a predetermined timing. These signals modulated by the modulator 60 are sent to the second transmission line 4 via the switch circuit 61 controlled by the frame assembling circuit 58, the BPF 62 and the amplifier 63.

In this embodiment, in the window frame for measuring the transmission delay time, response signals RSP from one or a plurality of concentrating distribution terminals 2 whose transmission delay time has been measured are sequentially arranged from the end side of one frame. This further improves the efficiency of the transmission line. That is, since the line distribution terminal 2 whose transmission delay time has been measured knows the transmission delay time, the response signal RSP can be transmitted at such timing based on the transmission delay time. When the response signal RSP from the final distribution terminal 2 whose transmission delay time has been measured is arranged on the terminal side of one frame, the number of the central distribution terminals 2 whose transmission delay time has been measured increases. Since the window frame period can be shortened accordingly, the number of subframes in one frame having a certain length can be increased, and the utilization efficiency of the transmission path is further increased.

FIG. 10 is a time chart for explaining the operation of this embodiment. In FIG. 10, (a) and (b) are the central unit 1.
The signals transmitted from the centralized distribution terminal 2 to the centralized distribution terminal 2 are viewed on the side of the central device 1 and on a certain centralized distribution terminal (2i) side, and the centralized distribution terminal 2i designates the centralized distribution terminal for itself. When the signal ASGi is detected as shown in (c),
The response signal RSPi is transmitted as shown in (d). FIG. 10 (d) shows the response signal RSPi viewed from the line concentrating / distributing terminal 2i side, and FIG. 10 (e) shows the response signal RSP from each line concentrating / distributing terminal 2 viewed from the central device 1 side. Where the concentration distribution terminal
In 2i, assuming that the measurement of the transmission delay time t pdi = (t di + t ui) has been completed, the response signal RSPi is transmitted so as to be arranged at the end of one frame as shown in FIG. 10 (a). When the other line concentrating / distributing terminal 2 finishes measuring the transmission delay time, the response signal is transmitted so as to be positioned before RSPi.

Next, the specific procedure will be described. Here, the central unit 1 manages the window length of the frame (that is, measures the time corresponding to the subframe used for communication from one frame time). Therefore, each line concentrating / distributing terminal 2 itself knows whether or not the line concentrating / distributing terminal has finished measuring the transmission delay time, and also controls whether or not the response signal RSP is transmitted. Here, the signal sent from the central unit 1 to the concentration distribution terminal 2 includes a concentration distribution terminal designation signal ASG. This concentrating distribution terminal designating signal ASG includes an RSP transmission permission indication bit as shown in FIG. The RSP transmission permission indication bit is set to "0" when the window length measured by the central unit 1 is equal to or longer than the maximum transmission delay time, and is set to "1" when it is smaller than the maximum transmission delay time. On the other hand, the concentration distribution terminal designation signal
The concentrating / distributing terminal 2 that has received the signal including the ASG knows whether or not the measurement of the transmission delay time has been completed as described above.

First, in the concentration distribution terminal 2 whose measurement is not completed,
When the RSP transmission permission indication bit is "1", the window length is insufficient, so the response signal RSP is not transmitted. On the contrary, when the RSP transmission permission display bit is "0", the window length is sufficient, so that the response signal RSP is transmitted. At the concentration distribution terminal 2 whose transmission delay time measurement has been completed, RS
Regardless of the P transmission permission indication bit, the response signal RSP is issued in a predetermined time slot of the next frame. The RSP transmission permission indication bit is "0", and the line concentrating / distributing terminal 2 for which the transmission delay time measurement has not been completed, for example, receives the response signal RSPi
In the case of transmitting the signal, the line concentrating / distributing terminal 2i outputs the response signal RSPi as soon as there are no carriers on the second transmission line 4. When the RSP transmission permission indication bit is "1" and the line concentrating / distributing terminal 2 which has finished measuring the transmission delay time outputs the response signal RSPi in the next frame, the carrier of the next frame arrives. , (1 frame length-RSPi length-t pd
i-α) is counted, and the response signal RSPi is sent to a predetermined slot set at the end of the frame based on this time. Note that α is a margin time for preventing the signal of the next frame and the response signal RSPi from colliding with each other.

Here, when the response signal RSPi is sent from the designated line concentrating / distributing terminal 2i in response to the line concentrating / distributing terminal designating signal ASGi, it is said that the central line device 1 has finished measuring the transmission delay time. If it is determined that the response signal RSPi is not transmitted or is not transmitted, it is determined that the concentration distribution terminal 2i is not operating. With this information,
The central unit 1 can confirm whether or not the other line concentrating / distributing terminal 2 can receive the call from a certain line concentrating / distributing terminal 2, and the exchange control is smoothly performed.

Then, in the line concentrating / distributing terminal 2i which has already finished measuring the transmission delay time, when receiving the line concentrating / distributing terminal designating signal ASGi from the central unit 1, the already measured transmission delay time t pd
Based on i, the response signal RSPi is transmitted so as to be positioned in the last slot of the next one frame, and further the response signal RSPi returned from the central unit 1 via the second transmission line 4 is received, Correct the signal transmission timing.

In the concentration distribution terminal designation signal ASG in FIG. 11, the MAUi address is the address of the designated concentration distribution terminal, and the MAU slot allocation information is the concentration distribution terminal to which the subframe slot is allocated. This is information for exchanging control information with the central unit 1 using the control data bit in the frame. As described in the above embodiment, the MAU slot allocation information is changed every time the concentrating distribution terminal 2 newly starts the exchange service in this system, but in principle, the allocation is performed so that there is no time slot available. Naturally it is done.
Further, although the information of the "subframe length" is omitted in FIG. 11, it is needless to say that it is desirable to add the information of the "subframe length" to the concentrating / distributing terminal designation signal ASG in this embodiment as well.

In the above description, the concentration distribution terminal whose transmission delay time has not been measured transmits the response signal RSP when the RSP transmission permission indication bit from the central device 1 is "0", but it is not always necessary. It is not necessary to do so, and the following aspects may be adopted.

When the central unit 1 manages whether or not the remaining time (window frame length) in the frame is sufficient, and further, each concentrating / distributing terminal 2 knows whether or not the transmission delay time measurement has ended. At this time, when the remaining time is sufficient based on these information, the central unit 1 sends the concentration distribution terminal designating signal ASG to the concentration distribution terminal 2 for which the transmission delay time measurement has not been completed. In that case, the line concentrating / distributing terminal 2 sends the response signal RSP without making any judgment.
Therefore, the RSP transmission permission indication bit is not required in the concentrated distribution terminal designation signal ASG.

The central unit 1 does not manage the transmission of the response signal RSP itself,
That is, in the case where the line concentrating / distributing terminal 2 manages the line delay distributing terminal 2 without having any information as to whether or not the transmission delay time measurement has been completed and whether or not the remaining time of the frame is sufficient.

(A) The length of the signal in one frame sent from the central unit 1 is measured, and if the time in the middle of the frame is sufficient for measuring the transmission delay time, the response signal RSP is sent in the frame.

(B) When the length of the signal in one frame transmitted from the central unit 1 is measured and the time (remaining time of the frame-1 length of subframe) is sufficient for measuring the transmission delay time, The response signal RSP is transmitted after the carrier of the transmission signal on the second transmission line 4 disappears in the next frame. However, in this case, the precondition is that the number of subframes in continuous frames changes by at most ± 1. (A)
The difference in (b) is the difference in the transmission timing (frame) of the response signal RSP, but this was taken into consideration in terms of consistency with the transmission of the response signal RSP in the concentration distribution terminal 2 whose transmission delay time has been measured. Due to that.

In other words, the line concentrating / distributing terminal 2 whose transmission delay time has been measured, after receiving the line concentrating / distributing terminal designating signal ASG and then detecting its own MAUi address, transmits the response signal RSP in a predetermined time slot of the next frame. For example, assume that there are two concentrating distribution terminals 2 that are physically adjacent to each other and that have consecutive addresses, and the concentrating distribution terminal 2 closer to the central device 1 has already finished measuring the transmission delay time, and another concentrating distribution terminal It is assumed that the terminal 2 is incomplete. Then, it is assumed that the central device 1 makes an RSP transmission request by the above method to the former concentration distribution terminal 2 in a certain frame (N) and to the latter concentration distribution terminal 2 in the next frame (N + 1). In this case, the former concentration distribution terminal 2 sends the response signal RSP at a predetermined time slot of the frame (N + 1) (usually the last slot in the frame). Therefore, when the latter line distribution terminal 2 sends the response signal RSP in the frame (N + 1), the response signals RSP may collide with each other. Therefore, if the latter concentrating / distributing terminal 2 also transmits the response signal RSP in the frame next to the frame in which the concentrating / distributing terminal designating signal ASG is received, it is not necessary to consider the collision.

Further, from the viewpoint of consistency, paying attention to the fact that the centralized distribution terminal 2 whose transmission delay time has been measured holds the information of the transmission delay time, and the centralized distribution terminal 2 whose transmission delay time has not been measured also has the transmission delay time. It is desirable to have the information of. That is, the concentration distribution terminal 2 for which transmission delay time measurement has not been completed
Therefore, the maximum transmission delay time should be held as the initial value of the transmission delay time to be held. In this way, it is apparently unnecessary to handle each concentration distribution terminal 2 at the level of transmission delay time measurement completion / non-completion.

In the process of measuring the transmission delay time as described above, it is necessary to know whether or not the measurement of the transmission delay time is completed for each concentrator / distributor, but whether or not the measurement of the transmission delay time is completed. For example, the detection of
Can be performed by the method of.

The line concentrating / distributing terminal 2 is provided with a flag circuit which is reset when the power of the line concentrating / distributing terminal is cut off, and which is set when the measurement of the transmission delay time ends after the supply of the power is started. In this case, the flag circuit may be supplied with power via the second transmission line 4.

Reset to the line concentrating / distributing terminal 2 by removing the line concentrating / distributing terminal from the first and second transmission lines 3 and 4,
A flag circuit is provided which is set after the first measurement after the concentration distribution terminal is connected to the first and second transmission lines 3 and 4.

The central device 1 is reset when the response signal RSP is not received from the concentration distribution terminal designated by the concentration distribution terminal designation signal ASG. In this reset state, the response signal RSP is reset.
Provide a flag circuit that is set when the RSP is received.

Of the above methods, when the flag circuit is provided on the side of the line concentrating / distributing terminal 2 as described above, it is desirable that the content of the flag circuit is retained unless the line concentrating / distributing terminal 2 is removed from the transmission line.

The above example is an example in which there is one concentration distribution terminal 2 which is requested to send the response signal RSP per frame, but the number of concentration distribution terminals may be plural. In this way, the response signal RS used for call setup at each concentration distribution terminal
The frequency of sending P can be increased, and the exchange service can be performed more smoothly. Hereinafter, an example of a specific frame configuration in such a case will be described with reference to FIG.

In this specific example, the configuration of the subframe is slightly different from that of the first embodiment (frame configuration as shown in FIG. 2). That is, in the above-described embodiment, each concentration distribution terminal has 1
Data was sent once per frame. On the other hand, in this embodiment, each concentrating / distributing terminal multiplexes data for two frames and sends the data only once in two frames.
Therefore, of the concentrator / distributor terminals involved in the switching operation, for example, the concentrator / distributor terminal with an odd address transmits data in a frame, and the concentrator / distributor terminal with an even address transmits data in the next frame. With such a configuration, the second
With the frame structure shown in the figure, dummy data can be omitted, and the frame can be used more effectively.

In addition, in the downlink slot signal (transmission signal on the second transfer path 4) in FIG.
The upstream parity of the "downstream parity" is obtained by receiving a signal from the centralized distribution terminal 2 in the central device 1 and obtaining the parity, and sending it back to the centralized distribution terminal 2 as an echo. When it is received, it is checked whether or not it matches the previously obtained parity. If it is different, it is determined that an error has occurred, and this is reported to the central unit 1 using the response signal RSP. The downlink parity is the parity of the signal received by the line concentrating / distributing terminal 2, and it is checked whether or not it matches the parity from the central unit 1. If they are different, it is determined that an error has occurred,
It is reported to the central unit 1 using the response signal RSP.

The "ASG mode" in the centralized distribution terminal designating signal ASG indicates whether the area after the centralized distribution terminal address (MAU address) is a reference level signal, call control information, MAU address 1, M
This is a signal for designating whether it is for the AU address 2. The "reference level signal" is for level control to prevent jitter from increasing due to variations in the levels of the upstream slot signals, which makes it difficult to establish bit synchronization.

The "RSP mode" in the response signals RSP1 and RSP2 is a signal for designating whether the MAU address is a reference level signal, call control information, or a report signal of the back detection associated with the above-mentioned parity check. is there.

The length of each part in the downlink slot signal and the uplink slot signal is as shown in the figure, and the unit s represents the number of symbols. The RF on length of the upstream slot signal is selected to be 1.5 s because the current data and the data one bit before are compared in the differential detection for demodulation of the 4-phase PSK signal which is the transmission signal. This is because the RF signal needs to be received at least one bit before the regular data. Regarding the RF off length, if the RF signal is momentarily turned on and off, the spectrum leaks out of the band and ripples occur back and forth. Therefore, it is necessary to spend about 0.5 s as shown in the figure. The blank time between each signal in the control window (concentration distribution terminal designation signal ASG + the period of the window frame) is sufficient if it is about 2 s, but it is set to 4 s as shown in the figure with a margin. Also, although not shown in FIG. 12, it is desirable to assign at least one symbol synchronization symbol and use it as a start delimiter after the RF is turned on in the upstream and downstream slot signals.

The present invention can be implemented with various modifications without departing from the scope of the invention. For example, the concentrating / distributing terminal designating signal ASG and the response signal RSP in the above-described embodiment can include the D channel in the common line signaling system which is being studied in so-called ISDN or INS, so the device may be configured based on the system. .

EFFECTS OF THE INVENTION According to the present invention, subframes are assigned to each line concentrating / distributing terminal only when a terminal device connected to the line concentrating / distributing terminal needs to communicate with another terminal device. Therefore, the utilization efficiency of the transmission line is remarkably improved, and it becomes possible to connect 2-3 times as many terminal devices with the traffic volume of a general private branch exchange as compared with the conventional method in which subframes are fixedly allocated. .

Further, in the present invention, one concentrating / distributing terminal designating signal is transmitted for each frame, and a plurality of subframes of the subsequent frame are controlled by the one concentrating / distributing terminal designating signal. Therefore, the transmission capacity of the concentrated distribution terminal designating signal in one frame can be significantly reduced compared to the case where a dedicated concentrated distribution terminal designating signal is transmitted corresponding to each of a plurality of subframes. Since it is possible to increase the number of frames, it is possible to further improve the transmission efficiency.

Further, according to the present invention, when requesting a call setup to the concentration distribution terminal, the central unit inserts a subframe length in addition to the call setup control signal and the number of the subframe to be used, and notifies the signal to the concentration distribution terminal. Then, the concentration distribution terminal sets the subframe transmission timing in consideration of the notified subframe length. Therefore, the subframe length can be changed according to the transmission amount of the signal, so that the subframes can be interchanged among a plurality of concentrating distribution terminals according to the transmission amount. Subframes can be used efficiently without waste, as compared with the case where is fixed.

[Brief description of drawings]

FIG. 1 is a block diagram of a system to which a concentrating distribution system according to an embodiment of the present invention is applied, and FIGS. 2 (a) and 2 (b) are diagrams showing a signal format on a transmission line in the embodiment, FIG. FIG. 4 shows the signal AS for specifying the concentration distribution terminal in the same embodiment.
FIG. 5 is a diagram showing the contents of G and the response signal RSP, FIG. 5 is a block diagram showing the internal configuration of the central unit in the same embodiment, and FIG. 6 is a block diagram showing the internal configuration of the centralized distribution terminal, FIG. 7 and FIG. FIG. 8 is a diagram for explaining setting of a window period, measurement of transmission delay time and control of signal transmission timing from a concentration distribution terminal based on the setting in FIG. 9, and FIG. 9 is concentration distribution in another embodiment of the present invention. Block diagram showing the internal configuration of the terminal, FIG. 10 is a timing chart for explaining the procedure of the transmission delay time measurement in the same embodiment, FIG. 11 is a diagram showing the frame configuration of the transmission signal in the same embodiment, 12 The figure shows a more practical frame structure of a transmission signal. 1 ... Central device, 2,2a to 2n ... Concentration distribution terminal, 3 ... First transmission line, 4 ... Second transmission line, 5 ... Terminal equipment, 1
3,34,55 …… Demodulator, 14 …… Concentrator distribution circuit, 15 …… Switch, 16,39,60 …… Modulator, 17,61 …… Switch circuit, 20
…… Adder, 21 …… Pilot signal generator, 22 …… Window control circuit, 35,57 …… Frame decomposition circuit, 36,59…
… Interface circuit, 37 …… Delay measurement circuit, 38, 58
...... Frame assembly circuit, 54 ...... Carrier detector, 56 ……
controller.

Claims (9)

[Claims] 1. A time-division signal transmission from a plurality of concentration distribution terminals to a central device via a first transmission line, and a signal transmission from the central device to the plurality of concentration distribution terminals via a second transmission line. In a concentrating distribution method in which signal transmission is performed in a time division manner, and the round trip transmission delay time by the first and second transmission paths is measured at the time of these signal transmissions, the second transmission path is used. One frame of a signal transmitted from the central device to the plurality of concentration distribution terminals, a plurality of subframes, a concentration distribution terminal designation signal for commonly controlling signal transmission by these subframes, and a transmission delay time. And a window frame for the measurement of time are multiplexed in a time-division multiplexed manner, and transmitted from the plurality of concentration distribution terminals to the central device in a time-division manner via the first transmission path. One frame of the signal to be transmitted has a fixed length configuration in which a plurality of subframes and a window frame for measuring the transmission delay time are time-division multiplexed, and the central device sets up a call to the plurality of concentration distribution terminals. When requesting
A call setting control signal, an address of the callee's callee's concentrating distribution terminal, a subframe number to be used, and its subframe length are inserted and transmitted. A plurality of concentration distribution terminals, a means for receiving a concentration distribution terminal designation signal from the central apparatus and transmitting a response signal within the period of the window frame; and a subframe included in the concentration distribution terminal designation signal from the central apparatus. A concentrating line, characterized by further comprising: means for controlling the transmission timing of the subframe to be sent to the first transmission path, based on the number and the subframe length and the measured round-trip transmission delay time. Distribution system. 2. The plurality of concentration distribution terminals are provided with measurement end detection means for detecting whether or not the own terminals have finished measuring the transmission delay time, and receive the concentration distribution terminal designation signal from the central unit. When it is determined that the measurement of the transmission delay time of the own terminal has been completed by the measurement completion detecting unit when the response signal is transmitted within the window frame period,
The concentrating distribution system according to claim (1), wherein the transmission timing of the response signal is sequentially arranged from the end side of one frame. 3. The end-of-measurement detection means of the concentration distribution terminal is
It has a flag circuit that is reset when the power of its own terminal is cut off and set when the measurement of the transmission delay time is completed after the power supply of its own terminal is started. The concentrating distribution system according to claim (2), which detects whether or not the measurement of the delay time is completed. 4. The concentrating distribution system according to claim 3, wherein the flag circuit receives power from the second transmission line. 5. The measurement end detecting means of the line concentrating / distributing terminal,
The own terminal is reset by being removed from the first transmission line and the second transmission line, and the transmission delay time is measured after the own terminal is connected to the first transmission line and the second transmission line. A flag circuit that is set when the operation is completed, and the flag circuit detects whether or not the own terminal has completed the measurement of the transmission delay time. Concentration distribution method described in paragraph. 6. A flag circuit which is reset when a response signal from the line concentrating / distributing terminal designated by the line concentrating / distributing terminal designating signal is not received, and which is set when a response signal is received in the reset function. The measurement end detecting means for detecting whether or not the concentration distribution terminal has finished measuring the transmission delay time by the flag circuit. Concentrated distribution method. 7. The concentrating / distributing terminal designating signal transmitted from the central unit includes a response signal transmission permission indicating bit, and the concentrating / distributing terminal, when the measurement of the transmission delay time is not completed, is addressed to itself. The means for detecting whether or not the response signal can be transmitted by the response signal transmission permission display bit is provided, and the means is provided.
Concentration distribution method described in paragraph. 8. The line concentrating / distributing terminal measures the length of a signal of one frame sent from the central apparatus, when the measurement end detecting means determines that the measurement of the transmission delay time is not completed. However, when the remaining time of the frame is sufficient for measuring the transmission delay time, it is provided with means for judging that the response signal can be sent out. Concentrated distribution method described. 9. The line concentrating / distributing terminal measures the length of a signal of one frame sent from the central device when the measurement end detecting means determines that the measurement of the transmission delay time is not completed. However, the method further comprises means for determining that the response signal can be transmitted when the time obtained by subtracting the length of one subframe from the remaining time of the frame is sufficient for measuring the transmission delay time. The concentrating distribution system according to claim (2).