JPH06104982A - Data communication system - Google Patents

Abstract

PURPOSE:To easily measure a length of a transmission line between a station equipment and plural terminal equipment and to allow the station equipment to optionally control a transmission timing of an incoming burst signal from each terminal equipment. CONSTITUTION:A station equipment 1 measures a required period of (m) from the transmission of an outgoing burst signal till the reception of an incoming burst signal sent from a specific terminal equipment 2. The station equipment is provided with data for a desired required period of time alpha for a terminal equipment and obtains a delay time beta added to require the arrangement of the incoming burst signal from the terminal equipment to a desired location by an equation of beta=alpha-m. The station equipment sends the outgoing burst signal with the information of delay time beta added thereto and the terminal equipment delays the transmission of the incoming burst signal according to the information of the delay time beta for its own equipment to be received. The station equipment revises the desired required period of time alpha in a group by adding or subtracting a prescribed value to/from the desired required time a for each of the plural terminal equipments.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a data communication system,
More specifically, the station device and a plurality of terminal devices are connected by a single communication path, and each terminal device transmits the upstream burst signal to the station device in time division based on the reception of the downlink burst signal transmitted by the station device. Data communication system.

Optical fibers have excellent characteristics such as low loss, wide band, and light weight. With the spread of wide band ISDN services including video services and facsimile services, the introduction of optical fiber communications into subscriber systems has been positively promoted. It is being advanced. Therefore, it is desired to construct a subscriber data communication system with low cost and high transmission efficiency, and the present invention was made as part of its research and development.

The present invention is also applicable to a so-called time division multiple access (TDMA) system in which a master station and a plurality of slave stations are connected via a single radio communication path using a communication satellite as a relay station. is there.

[0004]

2. Description of the Related Art FIG. 6 is a diagram for explaining an example of a subscriber data communication system. Conventionally, such a subscriber data communication system does not actually exist, but it is shown to explain the background art of the present invention. In the figure, 1
Station apparatus (NT), 2 ₁ ~2 ₃ terminal device, 30 trunk cable by the optical fiber, 301 _{to 303} are the same branch cable, 40 _{1-40 3} is an optical coupler.

In this subscriber data communication system
Is a station device 1 and a plurality of terminal devices 2₁~ 2₃A single light between
While connecting with the fiber communication line, the station device 1 is TCM
Each end based on the reception of the downlink burst signal transmitted by the method
End device 2₁~ 2₃Is a time division (TDMA method) station device 1
To transmit an upstream burst signal. In such a system,
Generally, an optical coupler 40 is appropriately provided along the trunk cable 30.₁
~ 40₃Branch cables 30 for each₁~
Thirty₃Through the terminal device 2₁~ 2₃Line can be connected
Be seen. Therefore, the station device 1 and each terminal device 2₁~ 2 ₃Between
The order of data exchange depends on the main cable 30.
It is preferable to follow the order from the viewpoint of system transmission control and operation.
Good

[0006]

However, since the line lengths of the respective branch cables 30 ₁ to 30 ₃ are usually different depending on the installation location of the terminal device, the station device 1 The transmission line lengths L up to the terminal devices 2 _{1 to} 2 ₃ do not always have the relationship of L ₁ <L ₂ <L ₃ . Therefore, in the station device 1, there may occur a case where the upstream burst signals sent from a plurality of terminal devices collide with each other or are received in an unspecified order, which causes a data communication system of this type. Is difficult to achieve.

An object of the present invention is to provide a data communication system capable of easily measuring a transmission path length between a station device and each terminal device and arbitrarily controlling the transmission timing of an upstream burst signal by each terminal device from the station device side. Is to propose.

[0008]

The above-mentioned problems can be solved by the structure shown in FIG. That is, the data communication system of the present invention is
The station device 1 and the plurality of terminal devices 2 ₁ to 2 _n are connected by a single communication path, and each of the terminal devices 2 ₁ to 2 _n is time-divided based on the reception of the downlink burst signal transmitted by the station device 1. In the data communication method of transmitting the upstream burst signal to the station device 1, the station device 1 measures the time m required from the transmission of the downstream burst signal to the reception of the upstream burst signal transmitted by the specific terminal device 2. is there.

[0009]

In the figure, a case will be described in which, for example, the terminal devices 2 ₁ and 2 _n are already in operation, and the terminal device 2 ₂ is added and operated here. The station device 1 sets a series of data A to _{N for the} terminal devices 2 ₁ to 2 _n (however, the terminal device 2 ₂ is empty).
And the upstream burst signals a and n (where n is not shown) are received from the respective terminal devices 2 ₁ and 2 _{n at the} timings shown in the figure.

In this state, if the terminal device 2₂Additional
If it is operated as it is, the transmission line length L of this example₁, L₂
In between₁> L₂Therefore, the terminal device 2₂Sent by
The upstream burst signal b'that is transmitted is the terminal device 2₁Up Bar
Strike signal a partially collides or the transmission order is
There is a risk of reversing as indicated by b'and a. There
Then, the station device 1 is preferably in advance, preferably, another terminal device 2₁，
Two_nTiming that does not affect communication with
The terminal device 2₂Below including the predetermined data signal B
By sending a burst signal,
From transmission of department TE to terminal device 2₂Upstream burst sent by
Time required to receive signal b'm ₂Measure.

As a result, the station device 1 can know in advance whether or not the upstream burst signal b'has collided or reversed due to the operation of the terminal device 2 ₂ . Moreover, since the required time m ₂ is nothing but the sum of the downlink transmission delay time d ₂ and the uplink transmission delay time d ₂ for the transmission path length L ₂ , the upstream burst signal is calculated based on the measured required time m _2. It is possible to easily obtain the additional branch cable length or the additional delay time β in transmitting the upstream burst signal b ′ that is necessary for aligning b ′ to the desired position.

Thus, the station device 1 can easily measure the transmission path length L to each terminal device 2, so that the builder of the present system actually measures the transmission path length L on a map or on the spot. Free from the burden. Preferably, the station device 1 includes data of a desired required time α for the terminal device 2, and an additional delay time β required for aligning the upstream burst signal of the terminal device 2 to a desired position is β = α. -M
Ask by.

[0013] That is, data of a desired duration α for the terminal device 2 ₂ In this example the α of the terminal device 2 ₁
Α ₂ longer than ₁ . Therefore, the additional delay time β ₂ required for aligning the upstream burst signal of the terminal device 2 _{2 at} a desired position is obtained by β ₂ = α ₂ -m ₂ . Further, preferably, the station device 1 transmits the information of the delay time β by including it in the downlink burst signal, and the terminal device 2 delays the transmission of the uplink burst signal according to the received information of its own delay time β.

That is, in this example, the station device 1 is connected to the terminal device 2 ₂
The information of the delay time β ₂ obtained with respect to is transmitted in the next downlink burst signal, and the terminal device 2 ₂ delays the transmission of the uplink burst signal b by β ₂ according to the received information of its own delay time β ₂ . Therefore, the upstream burst signal b is automatically aligned behind the upstream burst signal a. Therefore, in such a system, the transmission order and timing of the upstream burst signals are automatically optimized within the system without any external operation.

Further, preferably, the station device 1 sets the information of the delay time β to zero. As a result, each terminal device 2 ₁ to 2 _n
The true transmission line lengths L _{1 to} L _n can be easily measured at any time. Further, preferably, the station device 1 transmits a control signal for measuring the required time in a downlink burst signal and transmits it, and the terminal device 2 receives the control signal for measuring the required time, which is addressed to itself, so that the delay time of its own The information of β is temporarily set to zero and the upstream burst signal is transmitted. As a result, the station device 1 can easily measure the true transmission line length L up to the terminal device 2 while keeping the previous delay time β.

Further, preferably, the station device 1 changes the desired required time α in groups by adding or subtracting a constant value to each desired required time α for the plurality of terminal devices 2. Thereby, for example, when the terminal device 2 is newly inserted or deleted, the transmission timing of each upstream burst signal of the group of the terminal devices 2 before and after the new terminal device 2 can be easily shifted forward and backward for each group to be rearranged.

[0017]

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. The same reference numerals denote the same or corresponding parts throughout the drawings. FIG. 2 is a diagram showing the configuration of the data communication system of the embodiment. In FIG.
EM), 13 is a communication control unit (TDLP) that performs subscriber line data communication processing, 14 is a communication control unit (KDLP) that performs station line data communication processing, 15 is a common bus of the CPU 11, 16 is a time measurement unit , 17 is a bus decoder (BD),
18 is a flip-flop circuit (FF), 19 is a counter circuit (CTR), A is an AND gate circuit, B is a 3-state buffer circuit, 2 ₁ to 2 ₃ are terminal devices, 30 is an optical fiber trunk cable, and 30 ₁ ˜30 ₃ is the same branch cable, 40 ₁ ˜ 40 ₃ is an optical coupler, and 50 is an office line cable.

The operation of the data communication system of the embodiment having the above configuration will be described in detail below with reference to FIGS. 3-5 is an operation timing chart of the data communication system of the embodiment, FIG. 3 is an operation timing chart in the case where the terminal apparatus 2 ₁ and 2 ₃ is already running.

The station apparatus 1 periodically transmits a downlink burst signal to the terminal device 2 ₁ to 2 _3. An example of the downstream burst signal is a header H at the beginning and data A addressed to the terminal device 2 _1.
And data for the terminal device 2 ₂ (however, blank because it is before operation) and data C for the terminal device 2 ₃ . Further, the header H contains information on the transmission delay times β ₁ and β ₃ addressed to the respective terminal devices 2 ₁ and 2 ₃ .

Further, the station device 1 uses the transmission of the downstream burst signal, for example, the rear end portion TE as a reference, and each of the terminal devices 2 ₁ , 2
Each upstream burst signal a from _3, the desired duration alpha ₁ wants to receive a c, provided with alpha ₃ data therein, upstream burst signal a from the terminal device 2 _1, 2 ₃ and based on this, c is controlled to be received by the station device 1 at the timings of the desired required times α ₁ and α ₃ , respectively.

That is, for example, the terminal device 2₁Focus on the control of
Then, in this example, the station device 1 becomes the terminal device 2₁Delay time
β₁Information is transmitted by including it in the downlink burst signal.
On the other hand, the terminal device 2₁Is the transmission path delay d₁Down after
Start receiving the burst signal and then receive the end te.
When detected, the delay time β included in the header H ₁
According to the information of the time β₁Wait for the progress of
An upstream burst signal a for answer is transmitted. And this
The upstream burst signal a of the transmission line delay d₁After the passage of
Received by the device 1. Terminal device 2₃Also for
And thus each upstream burst signal a, c on the line
Are aligned as desired by the station 1.

Under such circumstances, the terminal device 2₂Add
And other terminal device 2₁, 2₃Affect the operation of
Without terminal device 2₂Consider the case of operating. in this case
In addition, the station device 1 and each terminal device 2₁, 2₂The transmission line length between
L respectively₁, L ₂And between these is L₁> L₂Seki
Suppose there is a person involved For this purpose, if the terminal device 2₂That
If it is operated up to this point, the station device 1
After the transmission of the end TE, when the required time γ elapses, the terminal device 2₂
Will receive the upstream burst signal b '. This
In this, the station device 1 is each terminal device 2₁~ 2₃Up from
Is it possible to receive the highest signal in the order of a, b, c?
However, it is not convenient in terms of processing the received data.
In addition to this, the station device 1 and the terminal device 2₂Transmission line length between
Depending on the terminal device 2₂Upstream burst signal transmitted by
b'is another terminal device 2₁Or 2₃Upward berth transmitted by
There is a risk of a collision with the traffic signal a or c in some cases.
It Therefore, the station device 1 is the terminal device 2₂Up berth from
Signal b ′ to the desired required time α₂Receive at the timing of
I want to

FIG. 4 is an operation timing chart when measuring the transmission line length between the station device 1 and the terminal device 2 ₂ .
The station device 1 operates the terminal devices 2 ₁ to 2 in _one frame cycle during operation.
For example, the following downlink burst signals are transmitted toward ₃ . That is, the downlink burst signal of this example includes the information of the delay time β ₂ = 0 included in the header H at the head and the terminal device 2.
Data B addressed to ₂ are included in the other terminal devices 2 ₁ , 2 ₃
The data addressed to is blank. As a result, in this one frame period, only the terminal device 2 ₂ transmits the upstream burst signal b, and the other terminal devices 2 ₁ and 2 ₃ do not transmit the upstream burst signals a and c.

[0024] Such control is an example of a consideration for the upstream burst signal a of the terminal device 2 ₂ of the uplink burst signal b and the other terminal device 2 _1, 2 _3, where the c not collide,
Not limited to the above method, any other method may be used. The CPU 11 of FIG. 2 energizes each input of the AND gate circuit A via the bus decoder 17 in advance when it is desired to measure the required time m. In this state, the communication control unit 13 outputs the measurement start signal SP by transmitting the rear end TE of the downlink burst signal, and the flip-flop circuit 18 is set. The count enable signal CE output from the flip-flop circuit 18 activates the counting operation of the counter circuit 19, whereby the counter circuit 19 counts up with the clock signal CK of a predetermined cycle.

Next, the communication control unit 13 outputs the measurement end signal EP upon receipt of, for example, the leading synchronization data of the upstream burst signal b'from the terminal device 2 ₂ , and thereby the flip-flop circuit 18 is reset. . The counter circuit 19 holds the count value m ₂ at that time, and the CPU 11 energizes the buffer circuit B via the bus decoder 17 to capture the count value m ₂ of the counter circuit 19 therein. The count value (required time) m ₂ is the downlink transmission delay time d ₂ and the uplink transmission delay time d due to the transmission line length L ₂ between the station device 1 and the terminal device 2 _2.
It is the sum of ₂ .

On the other hand, the station apparatus 1 is provided with a desired duration alpha ₂ data for pre-terminal 2 _2, additional delay when the terminal apparatus 2 ₂ transmits an upstream burst signals based on this β ₂ is calculated by β ₂ = α ₂ −m ₂ . FIG. 5 is an operation timing chart when the terminal devices 2 ₁ to 2 ₃ are operating.

The downlink verse transmitted by the station device 1 in this case
The delay signal β in the header H₁, Β₂，
β₃Data and each terminal device 2₁~ 2₃Data A to C
And are included. For example, the terminal device 2₂Focus on the behavior of
Then, the terminal device 2₂Is the transmission path delay d₂Down after
Start receiving the burst signal and then receive the end te.
When detected, the delay time β included in the header H₂
According to the information of the time β₂Wait for the progress of
The upstream burst signal b for the answer is transmitted. And this
The upstream burst signal a of the transmission line delay d₂After the passage of
Received by the device 1. Thereby, the terminal device 2₂Or
These upstream burst signals b have a desired required time α₂Taimi
Control to be received by the station device 1.
Becomes Terminal device 2 ₁, 2₃The same applies to the operation of
is there.

The station device 1 is used for each terminal device 2 in operation.₁
~ 2₃To zero the data of the delay time β of
From each terminal device 2₁~ 2₃True transmission line length L up to₁
~ L ₃Can be easily measured at any time. Also, the station device 1
Instead of the above, send down the control signal indicating the required time measurement.
The terminal device 2 transmits it by including it in a burst signal.
Receiving a control signal for self-timed time measurement
The information of the delay time β that it has is temporarily set to zero.
It may be possible to send the upstream burst signal after setting
Yes. In this way, the station device 1 will not be subject to the terminal device 2 when there is a delay.
True to the terminal device 2 while holding the data of β
The transmission line length L can be easily measured.

Also, the station device 1 changes the data of the desired required time α in groups by adding or subtracting a constant value to each desired required time α for the plurality of terminal devices 2. For example, when a new terminal device 2 ₂ ′ is inserted between the terminal devices 2 ₂ and 2 ₃ , the station device 1
Are, for example, the respective upstream burst signals a, of the terminal devices 2 ₁ , 2 ₂ .
There may be a case where it is desired to shift the transmission timing of b to the front side of the present. Even in such a case, the station device 1 internally has the terminal device 2
_1, 2 the desired duration alpha ₁ for _2, easily control groups changed only by subtracting the fixed value Δα to be shifted from the alpha ₂ data.

That is, the desired time α desired after the change
₁´ 、 α₂´ is α₁´ ＝ α₁-Δα, α₂´ ＝ α₂
−Δα. And new to this
Delay time β₁´, β₂´ is β₁´ ＝ β₁-Δα, β
₂´ ＝ β₂−Δα. Where β₁, Β
₂Since each value of is the delay time used until immediately before,
Terminal device 2₁, 2₂About β₁, Β₂= 0
The required time m₁, M ₂There is no need to remeasure.
Then, the station device 1 uses the new β thus obtained.₁´, β₂
By using the value of ', from the next one frame period
Is the terminal device 2₁, 2 ₂From the upstream burst signals a and b
Received at a timing that is shifted by Δα to the front side of the previous
You can get rid of it. Therefore, in the same manner as above, the terminal device
Two₂And 2₃And a new terminal device 2₂Easy to insert
And is put into operation.

On the contrary to the above, the transmission timing of the upstream burst signal c of the terminal device 2 ₃ may be controlled to be shifted to the rear side as compared with the conventional one, and thus, the terminal devices 2 ₁ to 2 in the present system. Arbitrary alignment control and rearrangement control for each upstream burst signal in ₃ can be easily performed.
In the above embodiment, the station device 1 measures the time m required from the transmission of the trailing end portion TE of the downlink burst signal to the reception of the leading end portion of the uplink burst signal transmitted by the specific terminal device, but is not limited to this. . The starting point and the ending point of the time measurement may be selected arbitrarily if they are commonly applied to each terminal device.

In the above embodiment, the single time measuring unit 1 is used.
6 is provided, but is not limited to this. For example, a plurality of internal software timers included in the CPU 11 may be used to obtain the required times m for a plurality of terminal devices all at once. In this case, the CPU 11 identifies which terminal device has transmitted the upstream burst signal based on the identification signal included in each upstream burst signal.

Further, in the above embodiment, one frame period during operation is used exclusively for measuring the transmission path length of the terminal device 2 _2. However, the present invention is not limited to this. For example, both the delay time beta ₂ = 0 of the terminal device 2 _2, the terminal device 2 _1, 2 ₃ the delay time beta
_1, once sufficiently large beta _3, since there is no fear that these upstream burst signals collide can achieve both communications transmission path length of the terminal device 2 ₂ measurements and the terminal device 2 _1, 2 _3. Terminal device 2 in the reverse also _1, 2 ₃ the delay time beta _1, beta ₃
May be left as it is and the delay time β ₂ of the terminal device 2 ₂ may be increased. In the latter case, the true transmission path length can be obtained by subtracting the delay time β ₂ from the required time measurement value m ₂ .

Further, although the above embodiment has described an example of the subscriber data communication system, the present invention is not limited to this. The data communication system of the present invention can be applied to a general data communication system such as a local area network for performing data communication between a plurality of computers. The present invention can also be applied to a so-called time division multiple access (TDMA) system in which a master station and a plurality of slave stations connect to each other via a single wireless communication path using a communication satellite as a relay station.

[0035]

As described above, since the data communication system of the present invention has the above-mentioned configuration, the transmission path length between the station device and each terminal device can be easily measured, and each terminal device transmits the upstream burst signal. The timing can be arbitrarily controlled and managed from the station device side.

[Brief description of drawings]

FIG. 1 is a diagram illustrating the principle of the present invention.

FIG. 2 is a diagram showing a configuration of a data communication system according to an embodiment.

FIG. 3 is an operation timing chart of the data communication system according to the embodiment.

FIG. 4 is an operation timing chart of the data communication system according to the embodiment.

FIG. 5 is an operation timing chart of the data communication system according to the embodiment.

FIG. 6 is a diagram illustrating an example of a subscriber data communication system.

[Explanation of symbols]

1 station device 2 _{1 to} 2 _n terminal device

Claims (6)

[Claims] 1. A station device (1) and a plurality of terminal devices (2 ₁ -
2 _n ) are connected by a single communication path, and each terminal device (2 ₁ to 2 _n ) is time-divided by the station device (1) based on the reception of the downlink burst signal transmitted by the station device (1). In a data communication method for transmitting an upstream burst signal to a mobile station, the station device (1) measures the time (m) required from the transmission of the downstream burst signal to the reception of the upstream burst signal transmitted by a specific terminal device (2). A data communication method characterized in that 2. The station device (1) comprises data of a desired required time (α) for the terminal device (2) and is necessary for aligning an upstream burst signal of the terminal device (2) at a desired position. The data communication system according to claim 1, wherein the additional delay time (β) is obtained by β = α-m. 3. The station device (1) transmits the information of the delay time (β) by including it in the downlink burst signal, and the terminal device (2) transmits the information of the delay time (β) of the uplink burst signal according to the received information of its own delay time (β). The data communication system according to claim 2, wherein transmission is delayed. 4. The data communication system according to claim 3, wherein the station device (1) sets the information of the delay time (β) to zero. 5. The station device (1) transmits a control signal for measuring the required time in a downlink burst signal and transmits it, and the terminal device (2) receives a control signal for measuring the required time addressed to itself. 4. The data communication method according to claim 3, wherein the information of its own delay time (β) is temporarily set to zero to transmit the upstream burst signal. 6. The station device (1) changes the desired required time (α) in groups by adding or subtracting a constant value to each desired required time (α) for a plurality of terminal devices (2). The data communication method according to claim 3, wherein