JPH01174194A - Line concentration distribution system - Google Patents

Abstract

PURPOSE:To eliminate need for the control of transmission timing with high accuracy at a single line distribution terminal equipment by using plural high speed clocks with different phase at the center equipment, sampling the reception signal and selecting a reception signal with a low bit error rate among them. CONSTITUTION:A signal received via an incoming line 3 is led from a diplexer 11 to a demodulator 12 and demodulated. A sampling circuit 13 uses plural high speed clocks with different phase generated by plural phase clock generators 14, and samples the signal received by the demodulator 12. Then an ASG/RSP processing section 18 sending/receiving an ASG/RSP signal with line concentration distribution terminal equipment checks each bit error to the sampled signal, obtains a clock obtaining a signal received and reproduced correctly and a selector 15 applies the control to obtain the signal reproduced by the clock.

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 located at various locations are connected to a central unit via a line concentration distribution terminal.

(Prior technology) Multiple terminal devices such as telephones are connected to a private branch exchange (PtlX).
) to form a network, it takes a lot of effort to directly connect each terminal device to the private branch exchange (PBX) by wiring, and the equipment costs are also large. That is, in most cases, these terminal devices are arranged in a plurality of buildings within the same building, or even in the same building, in a distributed manner on a plurality of floors. Therefore, each of these distributed terminal equipment and private branch exchange (PBX)
Laying individual signal cables between the two stations involves large-scale construction work and requires enormous equipment costs.

Therefore, as shown in FIG. 5, for example, line concentration and distribution terminals 2a and 2b are provided for each building or for each different floor.

~2n are provided, and these line concentration distribution terminals 2a, 2b, ~
2n and the central equipment 1 including the private branch exchange (PBX)
and the signal cable (first transmission line 3 and second transmission line 4)
Connect via. It is considered that the terminal device 5 is connected to the central device 1 via the line concentration and distribution terminal 2 by connecting the terminal device 5 to the line concentration and distribution terminal 2 closest to its installation location.

According to such a system configuration, not only is it easy to install signal cables between the core central device l and the plurality of concentration distribution terminals 2, but also the terminal equipment 5 can be connected to the nearest concentration distribution distribution terminal. Since it is only necessary to connect to 2, it is possible to flexibly construct a network.

In the system configured as described above, time sharing is carried out between the multiplexed line concentration distribution terminals 2 and the central unit 1 via two common transmission lines 3 and 4 as follows. Signal transmission is now performed.

That is, the central device 1 transmits the transmission data Do to each of the line concentration distribution terminals 2a, 2b, to 2n via the second transmission path 4, for example, in a frame structure as shown in FIG. 6(a).
, Do, ~Do, in the figure if, I
I 12.12 +n, dummy data indicated by the In line portion is sandwiched between the data and is transmitted in a time-division manner. Here, the subscript 1x attached to each data Do indicates the address of the line concentration distribution terminal, and 1x indicates the transmission data. Also ASG
is from the central device l to each concentration distribution terminal 2a, 2b, ~2n
This is a control signal given to

Call connection control, delay control, etc. are performed using this control signal ASG. One frame of the downlink transmission path is constructed by adding a predetermined window frame to such ASG signal and the transmission data.

On the other hand, each of the line concentration distribution terminals 2a, 2b, to 2n transmits transmission data DI, DI to the central device 1 via the first uplink transmission line 3, with a frame configuration as shown in FIG. 4(b), for example. ,~DI.

II, 11 12.12 +n, In are transmitted in a time-division manner. One frame of the uplink transmission path is constructed by adding a predetermined window frame to these transmission data. The R3P transmitted in this wind frame is
This is a response signal transmitted by the designated line concentration distribution terminal in response to the ASG signal for purposes such as call connection control and transmission delay time measurement, which will be described later.

By the way, each of the above-mentioned line concentration distribution terminals 2 is connected to different positions of the transmission line 3.4. For this reason, the transmission path length between each concentration distribution terminal 2 and the central device 1 is different for each concentration distribution terminal 2, and due to the difference in transmission path length, the transmission path length between each concentration distribution terminal 2 and the central device 1 is different. It is undeniable that there will be a difference in the signal transmission time of the signals transmitted between the two. Therefore,
If signal transmission is performed without considering the difference in transmission delay time, time slots are allocated in a time-division manner as described above, and the signals transmitted between each concentrator distribution terminal 2 and the central equipment 1 are transmitted over the transmission path. A problem occurs when a collision occurs.

Therefore, the present inventors have proposed patent application No. 59-288824, etc.
The transmission delay time in signal transmission between each concentration distribution terminal 2 and the central equipment 1 is measured using the ASG and R5P described above, and based on the measurement results, the transmission delay time is calculated from each concentration distribution terminal 2. It was proposed that the transmission timing of signals sent to the central device 1 be controlled to avoid signal collisions on the transmission path.

This method basically switches the ASG signal between a call control mode and a delay time measurement mode,
First, the mode of the ASG signal is set to a mode for measuring delay time. (2) The central device 1 sequentially sends a signal AC to a plurality of line concentration/distribution terminals 2 to designate the line concentration/distribution terminal.

(2) The line concentration distribution terminal 2 that has received this designation transmits a predetermined response signal RSP to the central device 1 using the window frame period described above in the next frame.

■ In the central device 1, this response signal RPS is sent to the central device 1.
The difference between the timing at which R3P actually arrives and the reference timing at which R3P should arrive after delay control is measured as the transmission delay time.

(2) Based on this transmission delay time, the transmission timing of the signal transmitted from the line concentration/distribution terminal 2 to the central unit 1 is adjusted and controlled.

However, in this way, each concentration distribution terminal 2a, 2b.

~2n, adjusts and controls the sending timing of the signal to be transmitted to the central device l, and each concentration distribution terminal 2
In order for the central device 1 to receive and reproduce signals respectively transmitted from the terminals a, 2b, to 2n using the same clock, for example, each of the line concentration distribution terminals 2a.

2b and 2n need to adjust and control the sending timing of the transmission signal using a clock that is 16 times faster than the signal transmission speed. Specifically, when the transmission rate of the signal transmitted using the first transmission line 3 is 4.096 Mbaud, each line concentration distribution terminal 2a, 2b.

~2n, the frequency of the sampling clock for controlling the sending timing of the transmission signal is 65.5.
This would require a frequency as high as 3GMHz.

In order to measure the transmission delay time, when the central device l detects the reception timing of the signals transmitted from each concentration distribution terminal 2a, 2b, to 2n, or each concentration distribution terminal 2'a, 2b, ~2n detects the reception timing of the signal sent from the central device 1 and adjusts and controls the sending timing of the transmission signal, the first and second
It becomes necessary to sample the signals having a transmission rate of 4.098 Mbaud transmitted via the transmission lines 3 and 4, respectively, using a clock of 65.53 [iMIIz, which is 16 times that frequency.

However, in order to configure the central unit 1 and each concentration distribution terminal 2a, 2b, to 2n so as to operate at such a high frequency, it is necessary to employ, for example, an ECL circuit, which unnecessarily complicates the configuration. There are problems such as an increase in power consumption and an increase in power consumption.

Moreover, the central equipment 1 and each concentration distribution terminal 2a, 2b, ~2
When detecting the reception timing using such a high frequency clock at
A quantization error of approximately 14 nscc) occurs, and in the worst case, these quantization errors are added together to produce a total of 2 clocks (approximately 28 nscc).
The error will be nScc). And due to this error,
For example, if an error of one clock occurs, there is a possibility that the bit error rate of the reproduced digital signal will deteriorate by a factor of 10 or more.

(Problems to be Solved by the Invention) As described above, although the line concentration and distribution method proposed by the present inventors has various advantages, its operation is limited to high speeds such as 65.536 MHz and locking. I need. Therefore, it becomes necessary to configure the device using an ECL circuit, which causes problems such as making the configuration unnecessarily complicated and increasing power consumption. Furthermore, despite operating using such a high-speed clock, there is a problem in that the bit error rate deteriorates due to the quantization error.

The present invention was made in order to solve the above-mentioned problems through subsequent research and development, and its purpose is to eliminate the need for high-speed clocks on the line concentration and distribution terminal side, and to eliminate bits caused by quantization errors. It is an object of the present invention to provide a line concentration distribution system that can effectively prevent deterioration of error rate.

[Configuration of the Invention (Means for Solving Problems)] The present invention provides a line concentration distribution system that transmits signals in a time-division manner between a central device and a plurality of line concentration distribution terminals via first and second transmission paths. In the method, the central device includes: (1) a means for generating a number of stages of clocks with different phases; and (2) a means for generating a plurality of clocks with different phases to generate a signal transmitted from each of the line concentration distribution terminals via the first transmission path. means for sampling each using
■ Check for errors in the signals sampled using each of these clocks, eliminate the signals in which errors are detected, and select one of the signals sampled with each of the above clocks as the received signal. The present invention is characterized in that it is provided with means for.

(Function) According to the present invention, each received signal is sampled in the central device using a plurality of high-speed clocks having different phases,
From among them, for example, a signal with a low bit error rate is selected as the received signal, so there is no need to control the signal transmission timing with high precision at each concentration distribution terminal, and the need for a high-speed clock at the concentration distribution terminal is eliminated. It becomes possible to eliminate As a result, the configuration of each line concentration and distribution terminal can be simplified and the cost can be reduced.

Moreover, as mentioned above, since the central unit selects signals with a low bit error rate, it is possible to minimize the bit error rate caused by quantization errors that occur during delay time measurement and signal transmission timing control, which were problems in the past. This makes it possible to realize efficient signal transmission.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

In this method, in a system constructed as shown in FIG. 5, the central unit 1 is configured as shown in FIG. 1, and each concentration distribution terminal 2a, 2b, to 2n is configured as shown in FIG. It is characterized by the fact that

In the central device 1 shown in FIG. 1, 11 is a transmission line 3.4
The signal received via the uplink line 3 is transmitted from this diplexer 11 to the demodulator 12.
is guided and demodulated. The sampling circuit 13 samples the signals received by the demodulator 12 using a plurality of high-speed clocks with different phases generated by the multi-phase clock generator 14, and samples the signals respectively sampled by the plurality of clocks. One is selector 1
5 to be alternatively taken into the frame disassembly section 18.

Here, the multi-phase clock generator 14 is configured using, for example, a phase difference control device previously proposed by the present inventors in Japanese Patent Application No. 175051/1984, as shown in FIG. A plurality of phase difference control modules 31a,
31b to 31n, the human power signal V as shown in FIG.
i to a plurality of clocks φ1.i with different phases. φ2. ~φn
It is configured to generate . That is, a plurality of modules 31a, 3 forming this multi-phase clock generator 14
1b, to 31n are a phase shifter 32 that shifts the phase of the input signal V[ by an amount corresponding to the control signal, a buffer amplifier 33 that shapes the output signal of this phase shifter 32, and this buffer amplifier. a phase comparator 34 that detects the phase difference between the output signal of the phase shifter 33 and the input signal to the phase shifter 32;
Compared to the previous “Or.

A differential amplifier 35 generates a control signal for the phase shifter 32, and thereby feedback-controls the amount of phase caused by the shifter 32.

The phase difference control module 31 configured in this manner adjusts the phase difference control signal voltage V from the phase of the human input signal.
retarded by a phase amount indicated by rer.

A plurality of phase difference control modules 31a, 31b, to 31n are connected in series in multiple stages to generate the clocks φl, φ2 . ~φn are generated sequentially.

In addition, the number of ships with different phases is φ1゜φ.
2. The period of ~φn is determined to be equal to the length of one pin point of the signal Φ transmitted via the transmission lines 3 and 4.

The sampling circuit 13 receives a plurality of clocks φ1 . φ2. 〜Repeat the above using φn: A
The signals RS received through the receivers 12 are each sampled. and the line concentration distribution terminal 2a.

The ASG/R3P processing unit 18, which transmits and receives ASG/RSP signals between 2b and 2n, performs a bit error check on each sampled signal using the clocks of the plurality of phases, and detects bit errors. The phase of the clock that obtains a signal that is correctly received and reproduced by excluding signals with a high rate is determined, and selective extraction of received data via the selector 15 is controlled.

The signal transmission from the central unit @1 is performed by combining the data sent from the exchange 19 and the ASG signal from the ASG/RSP processing section 18 in the frame synthesis section 20 as shown in FIG. 6 (a).
) is synthesized into the frame structure shown below.

Thereafter, this frame-structured signal is modulated via the modulator 21 and then sent to the second transmission path 4 via the typeplexer 11. And transmission delay time meter 1111 section 1
7 measures how far the arrival timing of the R3P signal deviates from the reference timing, using a reference clock of 65.5HMIIz, for example, according to the RSP signal sent from the line concentration distribution terminal in response to this ASG signal. There is. The above delay time measurement results are combined with the error detection results based on the frame check sequence of the signals sampled according to the plurality of clocks with different phases to calculate the optimal value of the signal transmission timing from the concentrator distribution terminal. served. And the calculation result is
The line concentration distribution terminal is notified as the above-mentioned ASG signal.

On the other hand, the plurality of line concentration and distribution terminals are connected to the transmission path via a diplexer 22 as shown in FIG. demodulate.

The demodulated signal is guided to the ASG/R3P processing section 24 to perform call setting control and delay time measurement control, and the received signal frame is disassembled by the frame disassembly section 25.
This is outputted to a terminal device 5 such as a telephone via a subscriber circuit 26.

Further, regarding the transmission signal given from the terminal device 5 via the subscriber circuit 26, the frame composition section 28, together with the RSP signal given from the ASG/R8P processing section 24, is configured as shown in FIG. 6(b). is generated as a frame signal. Then, the transmission timing is controlled by the transmission timing control section 27, and the signal is transmitted from the modulator 29 via the diplexer 22 to the first transmission path 3 toward the central device 1.

According to this system constituted by the central device 1 and the plurality of line concentration and distribution terminals 2a, 2b, to 2n configured in this way, each line concentration and distribution terminal 2a.

It becomes possible to select the optimum signal sending timing at the terminal and the sampling clock at the central unit 1 for each terminal 2b to 2n. In addition, in this way, it is possible to select the optimal sampling clock for the line concentration distribution terminal that uses it for each audio time slot, so it is possible to receive and process only the optimal data from among the received data with different sampling clocks. becomes.

In addition, as mentioned above, the central unit always receives and processes only the optimal data from among the sampling data from multiple clocks with different phases, so the timing of sending the signal sent from the concentrator and distribution terminal to the central unit is For example, the control accuracy is sufficient to be twice as high as the signal transmission rate of 4.09 [iMHz], and the control can be performed by simply using the rising and falling edges of the 4.096 MHz clock.

It becomes possible to suppress the operating speed required of the line concentration distribution terminal to a level as low as the signal transmission speed. In addition, since the central unit can be the only device that requires high-speed operation, the configuration of each of the multiple line concentration and distribution terminals can be simplified and
It is possible to reduce the cost and, in turn, simplify and stabilize the overall system configuration.

Furthermore, as mentioned above (the received signal is sampled using clocks with different phases and the optimal one is selected, it is possible to suppress quantization errors for the transmitted signal and reduce the bit error rate caused by this). In addition, if the transmission timing at the concentrator and distribution terminal is controlled using a clock with a frequency sufficiently higher than the signal transmission speed, for example, the central By monitoring the bit error rate of the sampling data using a plurality of phase difference clocks having the same or higher precision in the device 1, effects such as more precise control can be achieved.

Note that the present invention is not limited to the embodiments described above. For example, the number of audio data channels and the number of system control channels set in one frame may be determined according to the system specifications. Furthermore, the number of line concentration and distribution terminals connected to the system is not particularly limited.

In addition, the system requires how fast the signal transmission speed is compared to the signal transmission speed, how much lock is used to measure the delay time, and how many clocks with different phases are generated and the received signal is individually sampled. It may be determined according to the specifications to be used. Furthermore, the means for generating a plurality of clocks having different phases is not particularly limited. In short, the present invention can be implemented with various modifications without departing from the gist thereof.

C. Effects of the Invention As explained above, according to the present invention, transmission delay time can be measured with high precision in the central device without increasing the operating frequency required for the line concentration distribution terminal, and transmission delay time caused by quantization error can be measured with high accuracy. This provides great practical effects, such as effectively realizing efficient signal transmission with reduced bit error rates.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of the configuration of a central device in a line concentration and distribution system configured by applying an embodiment of the present invention, and FIG. 2 is a diagram showing an example of the configuration of a line concentration and distribution terminal in the same embodiment system. FIG. 3 shows 1 in the central device according to the embodiment.
Figure 4 is a diagram showing a configuration example of an S2 multi-phase clock generator, Figure 4 is a diagram showing multiple clocks with different phases, Figure 5 is a schematic configuration diagram of a concentration distribution system, and Figure 6 is a diagram showing a central unit and multiple FIG. 2 is a diagram showing a basic frame structure of a signal transmitted and received with a line concentration distribution terminal. ■...Central device, 2a, 2b, ~2n...Line concentration distribution terminal, 3.4...Transmission line, 5...Terminal equipment, 13
...Sampling circuit, I4...Multi-phase clock generator, I5...Selector, 17...Transmission delay time measuring section, 18.24...ASG/R3P processing section, 27.
...Transmission timing control section. Applicant's agent Patent attorney Takehiko Suzue m5 b

Claims (2)

[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-sharing signals from the central device to the plurality of line concentration and distribution terminals via a second transmission path. In the line concentration and distribution method in which signals are transmitted by division, the central device includes means for generating a plurality of clocks having different phases, and uses these multiple clocks to transmit signals from each line concentration and distribution terminal through the first transmission path. A line concentration distribution system comprising means for sampling and extracting each of the signals to be transmitted, and means for selecting one of the signals sampled using each of the clocks and making it a received signal. . (2) The line concentrator according to claim 1, wherein the selection of the received signal is performed by checking the signals sampled by clocks having different phases for errors and excluding signals in which errors are detected. Distribution method.