JPS62104232A - Satellite communication exchange system - Google Patents

Abstract

PURPOSE:To attain economical service using a TDMA equipment and over by demmand assign/pre-assign in common by providing a demmand assign controller between the DTMA equipment and a terminal equipment and applying the demmand assign connection within a range of a satellite line band subject to pre-assign connection. CONSTITUTION:As the pre-assign service constitution, each ground station 2 is added with a demmand assign controller 25 and a control station is added with a demmand assign line management equipment 16. Channels of a satellite line used in the demmand assign service are all set as pre-assign circuits used in common to the demmand assign controller 25. A communication request from a terminal equipment 3 is detected by a signal processing circuit 252 in the demmand assign controller 25 and informed to a demmand assign line managing equipment 16 via a control signal satellite line 51. The equipment 16 selects a line not in use out of the pre-assign lines set already for the demmand assign and assigns it.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a satellite communication switching system using a line using a TDMA (time division multiple access) system, and in particular to a system in which each call is connected in units of channels (demand assignment connection). .

(Prior art) Conventionally, in satellite communications, the common method is to set up a fixed line (preassigned line 16A) between ground stations, and use that line as a dedicated line between terminals connected to the ground station. Met. In this type of system, the line is held invalidly even when the terminal is not communicating, so the line is inefficiently used.
The disadvantage was that communication costs were high. For this reason, a satellite communication switching system is being considered in which the satellite link between ground stations is set up only during communication (demand assignment connection). However, in order to realize this demand assignment method, the process of detecting a communication request from a terminal, allocating an available satellite line, detecting the end of communication, and releasing the satellite line that was being used is required. This required dedicated ground station equipment that automatically performed the call each time a call occurred. In order to realize the pre-assignment service, a configuration as shown in FIG. 2 is generally used. Control station 1 that centrally manages satellite lines
A line setting command input manually from the console 15 connected to the satellite line management device 14 of the ground station 2 enters the control circuit 211 in the preassign TDMA device 21 of the ground station 2 via the satellite line 51 for control signals. By writing data to the address control memory of the compression/expansion buffer 212, the correspondence between the line from the terminal 3 and the satellite line is determined, and the communication satellite line 52 is set.

In such a pre-assignment method, a group of terminals housed in multiple ground stations commonly use all channels or a certain number of channels of the satellite link, and collisions of bursts transmitted by each station accommodating the terminal are avoided. In order to avoid this, since the terminal group is centrally managed, it is necessary to
A method of notifying a burst transmission request using a dedicated channel signal or a common channel signal may be used.

(1959 National Conference of Telecommunications Division of the Institute of Electrical Communication Engineers (10/59)
58-5 Utilization of Multi-Access Closed Network, and 58-9 TDMA System for Broadband Communication Networks) Furthermore, in order to realize a demand assignment service, a configuration as shown in FIG. 3 is conventionally used. The demand assignment TDMA device 24 of the local station 2 receives communication requests from the terminal line,
It has a signal processing circuit 244 that detects a communication path r, and each time it detects a communication request or a communication end, it notifies the satellite line management device 14 via the control signal satellite line 51, and the satellite line management device 14 transmits a notification to the TDMA device 24. compression/decompression buffer 242
The communication satellite line 52 is set for each call by controlling the .

This figure shows an example of a configuration of a centralized control system in which the satellite line management device 14 of the central control station 1 allocates and releases satellite lines according to requests. It is also possible to adopt a distributed control method in which both parties decide to use the communication satellite line 52 on an equal footing.

(Problem to be Solved by the Invention) Therefore, the functions of the TDMA device and the satellite line management device are different between the configuration for pre-assignment service and the configuration for demand-assignment service, and each service of pre-assignment/demand assignment is inevitably different. There is no choice but to create a separate service network using separate equipment.

Furthermore, if an attempt was made to change the preceding pre-assignment service to a demand assignment service, there was a drawback in that the TDMA device 21 and the satellite line management device 14 had to be replaced.

The present invention aims to improve the above-mentioned drawbacks.

(Means for Solving the Problems) The present invention economically realizes a demand assignment service by adding the minimum necessary equipment to the configuration for a pre-assignment service, and at the same time provides a pre-assignment service in advance. This makes it possible to easily add demand assignment services even after the service has been provided. The key point is that the demand assignment control device, which is connected via an interface as a user of the preassignment service, to the preassignment TDMA device that has the function of transmitting bursts in accordance with the individual channel signal or common channel number 48, uses the demandassignment service. The TDMA device is shared by both pre-assignment and demand-assignment services by providing the necessary functions of detecting communication requests, detecting completion of line allocation 1 communication, and releasing lines.

(Function) The present invention performs the above-mentioned communication request detection, line allocation within the preassignment line, communication end detection, and line release between the conventional preassignment line ground station equipment and the line from the terminal. The demand assignment method is realized by adding a device that performs this, and the TDMA device, antenna, and transmitting/receiving equipment necessary for the preassignment method to access the satellite line are shared with the preassignment method,
To inexpensively realize a demand assignment system in which a preassignment line is connected and used for each call, and at the same time to easily add a demand assignment service even after the preassignment service is provided in advance.

(Embodiment) FIG. 1 shows an embodiment of the present invention, in which the pre-assignment service configuration shown in FIG.
6 has been added. Since the demand assignment control device 25 is controlled by the demand assignment line management device 16, it is assumed that the 3 o'clock satellite communication ε line 51 has been set in advance for safe control.

The procedure for making a demand assignment connection is shown below. First, set the channels of the satellite line used for the demand assignment service on all demand assignment + l + (] display device 5.
, set it as a commonly used preassign circuit.

A communication request from the terminal 3 is detected by the signal processing circuit 252 in the I control device 25, and is notified to the demand assignment line management device 16 via the control signal satellite line 51. Demand assignment line The management device 16 selects and assigns an unused preassign line from among the preassign lines already set for demand assignment.As already mentioned, all the demand assignment control devices 25 use a common preassign line. ) line, but each time a communication line for demand assignment is set, the demand assignment control device operates the call path circuit 253 to connect to the TDMA line corresponding to the set communication line, and at the same time Send a signal to the device indicating that it is transmitting communication information, and have it actually send out a burst.

(The pre-assignment TDMA device 21 does not need to be controlled by the satellite line management device 14 for each communication request of the demand assignment service, and the pre-assignment line can remain set.) In this way, communication requests are accepted and received. Commonly used only by demand assignment control devices (pre-assignment)
It can send bursts to the line. In other words, a demand assignment line has been set.

Demand assignment control device 25 performs pre-assignment TDMA
As a method of sending a signal indicating whether communication information is being transmitted or not being transmitted in order to have the device 21 send out a burst, the demand assignment control device 25 and the pre-assignment TDMA device 2 can be used.
Possible methods include providing a control bit (in-channel signal) associated with each channel in the TDMA line between the two channels, and providing a common control line (out-channel signal).

In addition, regardless of the method of transmitting and receiving the control signal indicating whether communication information is being transmitted/not being transmitted, a centralized control method is adopted in which the demand assignment circuit management device 16 of the central control station 1 allocates and releases the demand assignment circuit. and demand assignment for each ground station; control circuit 25 in the v control device 25
It is also possible to adopt either a fractional control method in which the communication satellite lines 52 are determined to be used by each other on an equal footing.

Regarding the 8 lines of TDMA lines used for demand assignment, TDMA lines are prepared with a capacity corresponding to the total number of lines from terminals, and the TDMA device directly uses the satellite line band used for demand assignment by the demand assignment control device. The demand assignment control device connects the line from the terminal to the TDMA line corresponding to the vacant satellite line, and sends the burst transmission request to TD using the knee control bit associated with each channel of the TDMA line.
It is possible to notify the TDMA device of the channel number of the satellite line to be used and the burst transmission request using the common control line, where TDMA lines are prepared with a capacity corresponding to the number of simultaneous communications. be.

(Effects of the Invention) As explained above, according to the present invention, the T
By simply adding demand assignment control devices to pre-assignment equipment including a DMA device, it is possible to realize an economical service in which more than a TDMA device is shared by demand assignment/pre-assignment. Further, even after the pre-assignment service has already been started, it is possible to easily add the demand assignment service.

[Brief explanation of drawings]

Fig. 1 is a block diagram of the satellite communication exchange system according to the present invention;
The figure is a block diagram for realizing a conventional pre-assignment service, and FIG. 3 is a block diagram for realizing a conventional demand assignment service. l...Control station] -...Control station TDMA device 12...Control station transmitting/receiving device 13...Control station antenna ■...Satellite line management device 15...Operation console 16...Demand assignment Line management device 2...Ground station 21...Preassign TDMA device 211...Preassign TDMA control circuit 212--
・Pre-assigned TDMA compression/expansion buffer 213--
Preassign TDMA burst modem 22...Ground station transmitting/receiving device 23...Ground station antenna 24...Demand assignment TDMA device 241-...
Demand assignment TDMA control circuit 242...Demand assignment TDMA compression/expansion buffer 243...Demand assignment TDMA burst modem 244 +7+Demand assignment TDMA signal processing circuit 25-...Demand assignment control device 251...Demand assignment control circuit 252 --Demand assignment TDMA signal processing circuit 253 --Demand assignment speech path circuit 3 --Terminal 4 =? ! Jj star 51 - control signal satellite line 52 = communication satellite line

Claims (3)

[Claims] (1) A system in which multiple ground stations communicate via a communication satellite, and each ground station consists of a TDMA device, a transmitting/receiving device, and an antenna that has the function of transmitting bursts on a channel-by-channel basis in accordance with external signals. In the pre-assigned line system, between the TDMA device and the terminal, there is provided a switching function for arbitrarily connecting each terminal and the TDMA line to the TDMA device on a channel-by-channel basis, and a switching function for instructing the TDMA device to perform burst transmission. A satellite communication switching system characterized by having a demand assignment control device having a function of transmitting signals, and performing demand assignment connection within the range of a pre-assigned satellite line band. (2) The TDMA line is simplified by a capacity corresponding to the total number of lines from the terminal, the TDMA device directly indicates the satellite line band used for demand assignment to the demand assignment control device, and the demand assignment control device The line from the TDMA line is connected to the TDMA line corresponding to the vacant satellite line, and the burst transmission request is sent to the TDMA line using the control bits associated with each channel of the TDMA line.
The satellite communication exchange system according to claim 1, characterized in that the system notifies the device. (3) The TDMA line is prepared in a capacity corresponding to the number of simultaneous communications, and the TDMA device is notified of the channel number of the satellite line to be used and the burst transmission request via a common control line. Satellite communication exchange system described in scope 1.