JPS59191950A - Time division multi-direction communication system - Google Patents

Abstract

PURPOSE:To accelerate the establishment of synchronism when a circuit is restored by transmitting an information collating code for control of transmission. CONSTITUTION:When the communication is started, the transmission control information given from a master station is written to an RAM. The master station transmits an information collating code for control of transmission when a circuit is broken. When the circuit is restored, the collating code is received by a receiver RX and fetched to a register R to be compared with a prescribed code in a prescribed RAM by a comparator COM. When the coincidence is obtained from this comparison, a transmitter TX is controlled to start transmission in accordance with the transmission control information. While the rewriting is carried out with the RAM when no coincidence of collation is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical Field of the Invention The present invention relates to a time-division multidirectional system that connects a plurality of scattered slave stations and one common master station through wireless lines in a time-division manner. The present invention relates to a communication method, and particularly to a method for establishing initial synchronization of a slave station used here.

(2) Technology background Time division multidirectional communication will be explained with reference to FIG.

Figure 1 schematically represents the arrangement of each station and line connections in a time-division multidirectional communication network. In the figure, M indicates the master station;
511S2..., Sn indicates n scattered slave stations.

From the master station M, multiplexed on the time axis, for example, PCM
The signals are simultaneously sent in multiple directions, while each slave station S1. S
, . . . Sn sends out signals to the master station during their assigned time slots, and the signals from each slave station are arranged on the master station so that they are not arranged on the time axis.

That is, as shown in FIG. 2, from the master station M, the control channel C1 and the channel 1. directed to the slave station S are transmitted. ..., slave station Sr1
The channels n destined for each station are arranged and multiplexed on the time axis, and sent out to each slave station all at once. Each slave station S1. S2.
..., Sn, among the nine PCM signals sent from the master station, channels 1, 2, .・・・
, n selectively. On the other hand, each slave station SH+ 82
+..., 3n, signals are transmitted toward the master station in the time slots assigned to each station and after correction is made for the difference in signal propagation delay time of each station up to the master station. Therefore, in the master station M, the signals from each slave station are arranged in an orderly manner in one frame. For the sake of explanation, FIG. 2 shows a case in which one channel is allocated to each slave station, but channel allocation is arbitrary.
The number of channels for each station is appropriately determined within one frame according to the amount of transmitted information under control from the master station.

In the above-mentioned communication network, when lines with some slave stations are disconnected due to fading or the like, transmission from the slave stations is interrupted. In other words, the signal transmission from each slave station is synchronized with the clock of the master station and is performed based on the frame synchronization signal from the master station, and as mentioned above, if the signal from the master station is no longer received. This is because it becomes difficult to send signals during the time slot allocated to the own station.

When such a disconnected line is restored, the slave station synchronizes with the master station again and starts transmitting signals, but if it takes a long time to establish initial synchronization, the line will repeatedly be interrupted. In this case, there is a need to speed up the initial synchronization establishment because communication efficiency is significantly deteriorated.

(3) Conventional technology and problems When establishing initial synchronization due to the above line restoration, the ROM
If transmission control information such as the signal transmission position of the own station and the number of channels is fixed in a non-volatile storage means such as
As soon as the signal from the master station is received and the clocks are synchronized, signal transmission can be started. However, in communication networks that adopt the so-called demand assignment method, where the number of channels changes every moment according to the requests of each slave station,
The above transmission control information is written into a storage means such as a RAM provided in each slave station according to the received signal from the master station, and synchronization is established in order to control its own signal transmission timing. It takes a long time.

That is, tasks such as requesting channel assignment to the master station using a control channel, then writing transmission control information from the master station to RAM, and further confirming whether the written information is correct. It required

In addition, when the above-mentioned line disconnection occurs, the signal error rate is high because the reception level has decreased due to fading, etc., and the S/N is low, making it impossible to establish initial synchronization easily and in a short time. .

(4) Purpose of the Invention The present invention has been devised in view of the above-mentioned problems of the prior art, and is capable of establishing initial synchronization at high speed even when there is an interruption in the line due to fading or the like. The purpose is to provide a split multi-directional communication system.

(5) Structure of the Invention Furthermore, an object of the invention is to provide a time-division multidirectional communication network in which one master station and a plurality of slave stations are time-divisionally connected via a wireless line. In response to the interruption of the transmission signal from the slave station, the core slave station transmits a transmission control information collation code during the reception allocation time period, and when the slave station receives the code, it stores the code and its own RAM. Achieved by a time-division multidirectional communication method in which transmission control information stored in the RAM is checked against a predetermined code, and if the two match, transmission is started according to the transmission control information stored in the RAM. be done.

(6) Embodiments of the invention Hereinafter, embodiments of the invention will be described with reference to the drawings.

FIG. 3 is a block diagram showing the main part configuration of a slave station used in the communication method according to the present invention, in which Rx is a receiver, TX is a transmitter, R is a register, and RAM is a writable volatile memory. Memory and COM are used as comparison circuits.

Initially, when starting communication with the master station, the transmission control information sent from the master station using the control channel is loaded into the RAM, and signal transmission is started according to the contents of the RAM, as in the past. It is.

When the line is temporarily disconnected, the master station detects that the signal from the slave station is no longer being received, and performs the necessary transmission control at the same time that it was sending signals to the slave station. transmission control information verification code consisting of a signal for confirming information such as the signal transmission position, the number of assigned channels, or information written in the RAM of the slave station.

Thereafter, when the side line is restored, the core slave station synchronizes its clock with the signal from the master station and takes the received transmission control information collation code into register R. Register R
The content taken in is compared with a predetermined code in the RAMK in a comparator circuit COM, and if the two match, it is transmitted according to the transmission control information written in the RAMK itself. The transmitter Tx is controlled to start.

In other words, during signal interruption from the master station due to fading, etc.
This is to check whether the timing and number of channels of the signal to be sent by the own station have changed.Compared to the conventional method of updating all the contents written in RAM every time the line is disconnected, this method is much easier. Synchronization can be established in a very short time.

In addition, if the control information changes during the line disconnection and the contents of the register R and RAM do not match,
The RAM contents are rewritten in the same way as before. However, line disconnections due to fading and the like are usually sufficiently short compared to changes in transmission control information, and it is extremely rare for RAM to be rewritten during actual communication.

(7) Effects of the Invention According to the present invention, initial synchronization can be established after line restoration.
This can be easily done by simply checking the verification code from the master station, allowing signal transmission to be resumed at high speed.

Further, as is clear from the embodiments described above, the communication system according to the present invention is particularly effective in application to lines that are repeatedly interrupted.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an overview of a time-division multidirectional communication network, FIG. 2 is a diagram showing the channel arrangement therein, and FIG. 3 is a diagram showing the main part configuration of a slave station used in the communication system according to the present invention. It is a block diagram. In the figure, M is the master station, Sl + S2 + "' + Sn
is a slave station, Rx is a receiver, TX is a transmitter, R is a register, RAM is a writable nonvolatile memory, and COM is a comparison circuit.

Claims (1)

[Claims] In a time-division multidirectional communication network that connects one master station and multiple slave stations in a time-division manner via wireless lines, the master station connects the core slave station to the slave station in response to an interruption in the transmission signal from the slave station with which it is communicating. The transmission control information collation code is sent during the allocated reception time slot, and the slave station receives the code and uses the code and its own RAM.
The time-division multidirectional device is characterized in that the transmission control information stored in the RAM is checked against a predetermined code, and when the two match, transmission is started according to the transmission control information stored in the RAM. Communication method.