JPH0418822A - Satellite communication equipment - Google Patents

Abstract

PURPOSE:To previously prevent a congestion state or an uncommunicable state owing to a call restriction in a whole system by providing a means comparing the traffic quantity of a common signal line with a previously set prescribed value. CONSTITUTION:A monitoring means 42 monitors the traffic quantity of the common signal line and the comparison means 43 compares the traffic quantity of the common signal line, which the monitoring means 42 monitors with the previously set prescribed value. When the traffic quantity of the common signal line exceeds the previously set prescribed value as a compared result in the comparison mean 43, a call from oneself is restricted. Thus, the call can be restricted by oneself and it can previously be prevented that the system comes to the congestion state or the uncommunicable state owing to call restriction in the whole system.

Description

[Detailed description of the invention] [Purpose of the invention (industrial application field) To provide a satellite communication system that performs centralized control using a slotted random access method using a common signal line and communicates using a request allocation multiple access method. The present invention relates to an applied satellite communication device.

(Prior Art) FIG. 3 is a diagram showing a schematic configuration of this type of satellite communication system. This satellite communication system consists of one central control station 3
1, and a plurality of terminal control stations 32a.

32b., 32n, and a communication satellite 33. In response to a line allocation request (call origination) made by any of the terminal control stations 32a to 32n, the central control station 31 allocates an empty channel among the plurality of channels set by frequency division (FDMA method), and The same channel is also assigned to the destination specified in this call. Here, the central control station 31 and each terminal control station 328 to 32
The transmission and reception of signals between
This is performed using a slotted random access method using one DMA channel.

FIG. 4 is a diagram showing the format of signals transmitted through the common signal line. In this way, a TDM slot and a random access slot are set in one frame,
The central control station 31 sends out signals in the TDM slot, and the terminal control stations 32a to 32n send out signals in the random access slot.

FIG. 5 is a diagram showing the structure of burst signals inserted into TDM slots and random access slots. In this way, the burst signal is used to insert a preamble for inserting demodulation signals, a unique word for burst synchronization, data for requesting line assignment, notification data for assigned channels, and various other data. The data section is set.

By the way, in the satellite communication device applied to the terminal control stations 32a to 32n of the satellite communication system as described above, communication has conventionally been performed based on the control of the central control station 31 as described above, but the calling operation ( For line allocation requests),
When a call is made from a connected terminal (not shown) such as a telephone, a line allocation request is always issued regardless of the system status.

For this reason, when the number of calls in the entire system increases significantly due to an increase in the number of terminal control stations or a disaster occurs, the amount of traffic on the common signal line increases, and line allocation requests in random access slots become more difficult. Collisions increase, and retransmissions cause large transmission delays. Furthermore, the amount of traffic on the common signal line may further increase, resulting in a situation where communication is interrupted.

(Problems to be Solved by the Invention) As described above, conventional satellite communication devices applied to terminal control stations actively perform calling operations, so when the number of calls increases, There was a problem that it ended up in an axle wheel state.

Conventionally, when the central control station 31 is in the axle state,
Measures have been taken to restrict calls. However, with this method, new calls are prohibited all at once.
In addition to not being able to communicate at all, there is no way to prevent the situation from becoming a dead end.

The present invention has been made in consideration of these circumstances, and its purpose is to be able to self-restrict calls, and to prevent communications from being disabled due to the axle status or call restrictions in the entire system. An object of the present invention is to provide a satellite communication device that can prevent such problems from occurring.

[Structure of the Invention] (Means for Solving the Problems) The present invention includes a monitoring means for monitoring the traffic amount of a common signal line, and a method for setting the traffic amount of the common signal line monitored by the monitoring means in advance. and a comparison means for comparing with a predetermined value, and if as a result of the comparison by the comparison means, the amount of traffic on the common signal line exceeds a preset predetermined value, the calling from the self is restricted. did.

(Function) According to the present invention, the amount of traffic on the common signal line is monitored, and if the monitored amount of traffic on the common signal line exceeds a predetermined value set in advance, the call is not issued from the user. Regulated.

Therefore, the amount of traffic on the common signal line is suppressed to about the predetermined value.

(Embodiment) Hereinafter, a satellite communication device according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of the communication equipment. In the figure, 1 is an antenna device, and 2 is a transmitting/receiving device. The transmitting/receiving device 2 converts a high frequency signal obtained by the antenna device 1 into an intermediate frequency signal to generate an intermediate frequency signal. The intermediate frequency signal output from the transmitting/receiving device 2 is given to the modulation/demodulation device t3. The modem 2 device 3 includes n modems 11 (11a, 11) for normal communication corresponding to each of n channels set by frequency division in the satellite communication channel.
blln) and one modem 12 for line control.

Here, if the signal received by the antenna device 1 and the transmitting/receiving device 2 is a signal of a channel set to a common signal line (hereinafter referred to as a C5C signal), the transmitting/receiving device 2 transmits the C5C signal to the modem 12. give. The modulator/demodulator 12 demodulates the signal given from the transmitting/receiving device 2 and supplies it to the line control device 4 .

The line control device 4 includes a main control section 41 and a C8C signal monitoring circuit 4.
2 and a comparison circuit 43, and the C8C signal given from the modem 12 is input to the main control section 41 and the C8C signal monitoring circuit 42. And the main control section 41
TD in 8C signal! The allocated channel is determined based on the data included in the v1 frame, and well-known line control processing such as permitting the operation of the modulator/demodulator 11 corresponding to this allocated channel is performed. In addition, the C8C signal monitoring circuit 42i statistically monitors the traffic link amount of the common signal line based on the data included in the random access slot in the C5C signal (for example, the number of line allocation requests generated per unit time). (counting, etc.) and notifies the comparison circuit 43 of the traffic amount. The comparison circuit 43 compares the traffic amount notified from the C5C signal monitoring circuit 42 with a preset reference value, and notifies the main control unit 41 of the comparison result.

When the modem 11 corresponding to the assigned channel is permitted to operate by the main control unit 41, the intermediate frequency signal outputted from the transmitter/receiver 2 and given to the modem 3 corresponds to the channel through which the signal was transmitted. The signal is applied to the TJI modulator 11, where it is demodulated and an audio signal is reproduced. The audio signal reproduced by the modem 11 in this way is
A relay line 6 (6a, 6b..., 6n) of a wired communication network (for example, public telephone network, etc.) is connected via the interface device 5.
sent to. Note that 7 is a switch for the wired communication network.

On the other hand, the audio signal arriving via the relay line 6 is given to the modulation II device 3 via the interface device f5. The audio signal arriving at this time is transferred to the modem 11 interface r! corresponding to the assigned channel. It is given by l15. In this way, the audio signal given to the modem 11 is modulated by the modem 11, and then sent to the transmitting/receiving device rj!
The frequency is converted at t2, and the signal is transmitted from the antenna device 1 toward the communication satellite.

By the way, the main control unit 41 of the line control device 4 includes, for example, a microcomputer as a main control circuit, and in addition to the control means for performing the line control processing described above, it also includes a call regulation circuit provided in the interface device 5. A call restriction control means 41a is provided which controls the call restriction control means 5a.

Next, the operation of the present satellite communication device configured as described above will be explained according to the processing procedure of the main control section 41.

First, in a standby state, the main control unit 41 monitors the occurrence of outgoing and incoming calls in steps a and b as shown in FIG. Then, in step d, it is determined whether the traffic amount is larger than a preset reference value or not, depending on the comparison result thus obtained. Here, the reference value set in the comparison circuit 43 is a value slightly lower than the amount of traffic generated in the axle wheel state, and is appropriately set according to the system.

In this standby state, when a call signal is received by a call detection unit (not shown) and notified to that effect, the main control unit 41 shifts the process from step a to step e, and connects the line at step knob e. Outputs an allocation request signal. Here, the line allocation request signal outputted from the main control section 41 is modulated by the modulator/demodulator 12 and then given to the transmitting/receiving device 2 . The transmitting/receiving device 2 converts this manually input signal into a burst signal according to the format shown in FIG.
It is transmitted from the antenna device 1 to the communication satellite during the random access slot period in synchronization with the reception timing of the DM slot. The line assignment request signal thus sent out is transmitted to the central control station via the communication satellite. The central control station receives this transmitted line allocation request signal, allocates an empty channel in response to it, and outputs a C8C signal containing information indicating the allocated channel to the communication satellite.

After outputting a line allocation request signal in step e, the main control unit 41 performs line connection processing in step f. This line connection process is performed as follows. That is, first, the allocated channel is determined from the C5C signal output from the central control station as described above. After allowing the modem 11 to operate corresponding to the assigned channel, it is checked whether the line settings have been made correctly and a continuity test is performed.

On the other hand, the main control unit 41 receives the received C in a standby state.
When the calling data of the own station is sent in the TDM slot of the 5C signal, the main control unit 41 determines that there is an incoming call, and moves the process from step b to step f.

In step f, the main control unit 41 performs the line connection process described above.

Thus, in response to the occurrence of an outgoing or incoming call, line connection processing is performed in step f, and in a state where a call is in progress, the main control unit 41 connects the satellite communication device to the trunk line 6 and the exchange in step g. In step h, it is repeatedly determined whether the telephone connected via 7 is on-hook (the one in use) and whether a release command has been transmitted by the C8C signal. Here, when the telephone on the side of this satellite communication device is hooked ON, the main control unit 4
] moves the process from step h to step i, and in this step i outputs a recovery signal for the channel being used by the ON-hook telephone. This main control section 41
The recovery signal outputted by is modulated by a modulator/demodulator 2, frequency-converted by a transmitting/receiving device 2, and sent from an antenna device 1 toward a communication satellite. The restoration signal thus sent out is transmitted to the central control station via the communication satellite. The central control station receives the transmitted recovery signal and sends out a channel release command corresponding to the recovery signal in the CSC signal.

After outputting the restoration signal in step i, the main control section 41 waits in step J for a release command to be given from the central control station as described above.

Then, the release command sent from the central control station is transmitted via the communication satellite, and the antenna device 1. It is received and demodulated by the transmitting/receiving device 2 and the modem 12, and then sent to the main controller 4.
1, the main control unit 41 switches the process to step j
The process moves to step k.

On the other hand, when the telephone on the other party's satellite communication device side is turned on during a call, the central control station outputs a release signal in response. At this time, the main control unit 41 repeatedly determines in steps g and h whether a 91 disconnection and release command has been transmitted to determine whether the telephone on the side of the satellite communication device is on-hook. Therefore, the release command is issued to antenna device W1. Transmitter/receiver 2 and modem 1
2 and is sent to the main control unit 41. In step h, the main control unit 41 determines that there is a release command and moves the process to step k.

Thus, the main controller 41 performs step j or step h.
When a release command is given at step k and the process moves to step k, well-known line disconnection processing is performed at step k. After this,
The main control unit 41 outputs a recovery confirmation signal in step g, and ends the process. In step g, the main control unit 4
The recovery confirmation signal outputted from antenna device 1 is modulated by modem 12, frequency-converted by transmitting/receiving device 2, and sent from antenna device 1 to a communication satellite. When the central control station receives the restoration confirmation signal transmitted from the communication satellite, the central control station recognizes the channel as an empty channel.

Processing during normal communication operation is performed as described above.

By the way, when the amount of traffic on the common signal line increases and becomes larger than the reference value set in the comparison circuit 43, the main control unit 41 is notified of this fact. In response, the main control unit 41 shifts the process from step d to step m. In step m, the main control unit 41 controls the call restriction circuit 5a using the call restriction control means 41a,
Perform calling restrictions. Here, when the call restriction circuit 5a is placed in a call restriction state under the control from the main control unit as described above, the SR line of some predetermined trunk lines 68 to 6n is connected to the ground. do. As a result, calls made via the relay line 6 where the SR line is connected to the ground are invalidated, and the number of calls made by the satellite communication device is reduced.

Thus, according to this embodiment, when the amount of traffic on the common signal line exceeds a certain reference value, the SR lines of some trunk lines 6 are connected to the ground, and the transmission is carried out via the trunk lines 6. Since calls are not accepted, it is possible to prevent the traffic volume on the common signal line from increasing to the point where a wheel spindle condition occurs. Therefore, it is possible to prevent the wheel from turning into an axle condition.

Furthermore, since the SR lines of all the relay lines 6 are not connected to the ground, but calls are accepted on some of the relay lines 6, communication can continue.

Note that the present invention is not limited to the above embodiments. For example, a plurality of reference values may be set in the comparison circuit 43, and the number of relay lines 6 connecting the SR line to the ground may be controlled in stages.

Furthermore, the method of restricting call origination is not limited to connecting the trunk line 6O5R to the ground, and can be implemented in various ways. Furthermore, the monitoring of the traffic amount on the common signal line is not limited to the method mentioned in the above embodiment, but can be implemented using various methods. In addition, various modifications can be made without departing from the gist of the present invention.

[Effects of the Invention] According to the present invention, there is provided a monitoring means for monitoring the amount of traffic on a common signal line, and a comparison means for comparing the amount of traffic on the common signal line monitored by the monitoring means with a predetermined value set in advance. As a result of the comparison by this comparison means, if the traffic volume of the common signal line exceeds a preset value, calls from the self are restricted, so that it is possible to determine whether the axle status or This provides a satellite communication device that can prevent communications from becoming impossible due to call restriction in the entire system.

[Brief explanation of the drawing]

1 and 2 are diagrams for explaining a satellite communication device according to an embodiment of the present invention, FIG. 1 is a block diagram showing the configuration, and the second factor is the main control unit 41 in FIG. A flowchart showing the processing procedure and FIGS. 3 to 5 are diagrams each explaining the prior art. 1... Antenna device, 2... Transmitting/receiving device, 3...
Modulation/demodulation device, 4... Line control device, 41... Main control unit, 41a... Call regulation control means, 42... C5C signal monitoring circuit, 43... Comparison circuit, 5... Interface device, 5a... Call restriction circuit, 6 (68 to 6n) relay line, 11 (lla to 1ln), 12... Modulator/demodulator. Applicant's agent Patent attorney Takehiko Suzue No. 2 "1"

Claims (1)

[Scope of Claims] A satellite communication device applied to a satellite communication system that performs centralized control using a slotted random access method using a common signal line and communicates using a request allocation multiple access method, comprising: monitoring means for monitoring a traffic amount; comparison means for comparing the traffic amount of the common signal line monitored by the monitoring means with a predetermined value set in advance; and as a result of the comparison by the comparison means, the traffic amount of the common signal line If the traffic amount exceeds a preset value,
1. A satellite communication device comprising: a call restriction means for restricting calls from the satellite.