KR19980069601A - External Call Routing Method in Satellite Communication System - Google Patents

Abstract

The present invention relates to a method for designating an external call path in a satellite communication system that allows a user to selectively designate any base station among a plurality of base stations combined with a public switched network when attempting an outgoing call to a public switched network (PSTN) in a satellite communication system. A satellite communication system for providing a communication function between subscribers by connecting a plurality of base stations respectively coupled to a plurality of subscribers and a public switched network through satellites; When a predetermined call request signal is received from an arbitrary base station, a call type determination step of determining whether the corresponding call is an internal call or an external call, and when the call type is an internal call in the call type determination step, a series of internal call processing operations When the call type is an external call in the call processing step and the call type determining step, the relay line occupancy control is performed by searching for the base station number based on the relay line code and outputting the relay line occupancy request signal to the base station. Characterized in that it comprises a control step.

Description

External Call Routing Method in Satellite Communication System

The present invention relates to a communication system using satellites, and in particular, a satellite communication system can selectively designate any base station among a plurality of base stations combined with a public switched network when attempting an outgoing call to a public switched telephone network (PSTN). The present invention relates to an external call routing method in a satellite communication system.

At present, satellite communication, which allows subscribers who are located at remote sites to make calls through satellites, is becoming increasingly common. Such satellite communication is mainly required for long distance communication between countries because it does not require a separate signal line for a call. It is usefully used as a communication method in a mountainous country like Korea.

In the satellite communication, a pre-assignment multiple access (PAMA) method of allocating communication channels for each subscriber before a predetermined time in accordance with the channel assignment method and a DAMA (Demand Assignment Multiple) for allocating communication channels according to a subscriber's request. Access) method, in general, the DAMA method for voice communication and the PAMA method for data communication are adopted in consideration of the cost and effectiveness of the communication channel.

1 is a block diagram showing the overall system configuration of a general satellite communication system according to the DAMA method.

In Fig. 1, reference numeral 1 is a satellite having a plurality of communication channels, 2 is a central control station for controlling the entire satellite communication system, and 3 (3A, 3B) is an exchanger (11A, 11B) or a telephone (12A, 12B). And interface functions for terminals such as data terminals 13A and 13B and facsimile 14A and 14B, such as a computer, and communication between the various terminals through data transmission and reception with the central control station 2. It provides a base station.

In FIG. 1, reference numeral S denotes a service channel for transmitting and receiving control data, and T denotes a traffic channel for transmitting and receiving data or voice.

Here, the service channel (S) is one outbound channel, which is a transmission channel from the central control station 2 to the base station 3, and a transmission channel from the base station 3 to the central control station 2. It consists of up to four Inbound channels.

The outbound channel uses a time division multiplexing (TDM) scheme (TDM channel) and transmits synchronization and data packets. Each packet of this TDM channel has a base station identification code for identifying a specific base station or a wide area identification code shared for transmission to all base stations.

The inbound channel uses a random slotted aloha scheme in which several base stations 3 communicate with the central station 2 (S-ALOHA channel). This S-ALOHA channel consists of 18 packets, divided into 14 random packets used for call processing functions and 4 reserved packets for functions related to network operation and maintenance. do.

In the above-described configuration, the central control station 2 transmits a control message through a service channel in a normal state and then, based on a response message sent from the base station 3, that is, communication It performs a polling function to check the available capacity or the utilization status of the communication channel. When there is a call request from a specific base station, for example, the base station 3A to the terminal of the base station 3B, it is determined whether the corresponding base station 3B is in a state in which communication is possible based on the information obtained in the polling process. In the case of the communicable state, the available traffic channel T of the satellite is allocated to both base stations 3A and 3B so that both base stations 3A and 3B can directly communicate with each other.

Subsequently, when the communication between the base stations 3A and 3B is terminated and the communication termination signal is applied through the service channel S from the base station 3A, which has been requested for communication, the central control station 2 is applied to both base stations. By executing the communication termination process, the traffic channel T which has been provided to both base stations 3A and 3B is released.

2 is a block diagram showing the configuration of the central control station 2 described above.

In the drawing, reference numeral 21 denotes an antenna for transmitting and receiving satellite 1, an uplink signal, and a downlink signal, and 22 denotes an antenna for transmitting and receiving through the antenna 21 by using a polarization property of frequency. Orthogonal Mode Transducer that separates and inputs and outputs a signal, and Low Noise Amplifier, which low-amplifies 12.25 to 12.75 GHz downlink frequency signal inputted through the Orthogonal Mode Converter, this low noise amplifier A down converter for converting a frequency signal applied through an amplifier into an intermediate frequency signal IF of 70 MHz, for example, an IF signal of 70 MHz applied from an IF combination / distributor 23 to be described later. Is an upconverter for generating an uplink frequency signal by converting the microwave into a microwave of 14.0 to 14.5GHz, and an uplink frequency signal output from the frequency upconverter. An RF processor configured to include a high power amplifier (High Power Amplifier) for amplifying.

In addition, reference numeral 23 separates and outputs the intermediate frequency signal applied from the RF processor 22 into a plurality of intermediate frequency signals, and is applied from the SCPC (Single Channel Per Carrier) channel unit 24 to be described later. IF is a combination divider (Combiner / Distributer) for combining and outputting the intermediate frequency signal, 24 is a network control unit to demodulate, decode and output the intermediate frequency signal applied from the IF combination distribution unit 23, which will be described later SCPC channel unit that encodes, modulates and outputs the message output from (30).

Here, the IF combination distribution unit 23 is adopted for system scalability when using a plurality of SCPC channel units 24.

Reference numeral 30 denotes each base station based on a response message transmitted from the base station 3 after sending the control message to each base station 3 through a predetermined SCPC channel unit 24 for transmitting and receiving the control message. Perform a polling function to check the state of (3), and if there is a call request from a specific base station, determine whether the other base station is in a communication capable state based on the information obtained in the polling process. In this case, the network control unit performs system control, such as assigning an available traffic channel (T) of a satellite and a modem to both base stations so that both base stations can directly communicate with each other, and 40 denotes an operator and a predetermined operator. It is a network management device that is connected through a terminal and performs overall management of a satellite communication system.

Next, the operation of the central control station 2 having the above-described configuration will be described.

In a normal state, the network controller 30 checks the state of each base station by performing a polling operation for each base station 3.

That is, the network controller 30 generates a message of the TDM stream based on the packet data for checking the status of each base station and outputs it to an arbitrary SCPC channel unit 24. Then, the SCPC channel unit 24 encodes, modulates and outputs the TDM message, and this frequency signal is converted into an uplink frequency signal and transmitted to each base station 3.

On the other hand, the response message received through the satellite 1 from each base station 3 is converted into a predetermined intermediate frequency signal, and then applied to the SCPC channel unit 24 through the IF combination / distributor 23 to demodulate. After decoding, the data is output to the network controller 30. Then, the network controller 30 extracts packet information from the response message and stores the packet information in a predetermined memory to hold state information for each base station.

In addition, the above-described polling operation is continuously performed for each base station.

The reference MPH (Main PCM Highway) is a data bus through which information data such as a voice signal or a data signal is transmitted and received, and the UPH (Utility PCM Highway) is a control bus through which control data is transmitted and received between the base station controller 30 and each device. to be.

On the other hand, the base station 3 is coupled to the satellite network subscribers (or internal call subscribers) through a predetermined subscriber access board, respectively, and is connected to any switch in the public switched network by an E1 relay line through a predetermined trunk access board. It provides communication function with public switched subscribers (or external call subscribers).

More specifically, in general, since the public switched network is a massive communication system connecting the nationwide subscribers in Korea, there are many regional exchanges, and the base station 3 directly connected to the subscribers in the satellite communication system also exists. There are a plurality of base stations (3) of the satellite communication network and the regional exchanges of the public switched network are implemented to interwork with each other by connecting to each other E1 relay line.

However, when a call is requested from an internal call subscriber to an external call subscriber, the satellite communication system sets a public path by selectively designating a switch closest to the called external call subscriber among a plurality of regional exchanges connected to a plurality of base stations. It is essential to establish the shortest distance to reduce the overall load on the switching network.

Accordingly, the present invention has been made in view of the above circumstances, and in the satellite communication system, when an internal call subscriber attempts to make an outgoing call as an external call subscriber of a public switching network (PSTN), a plurality of local exchanges of the public switching network are combined with a plurality of regional exchanges. It is an object of the present invention to provide an external call routing method in a satellite communication system that can selectively designate a base station that is closest to a called subscriber to minimize the load of the public switched network among the base stations.

1 is an overall system configuration for explaining the outline of a general satellite communication system.

FIG. 2 is a block diagram showing the configuration of the central control station 2 in FIG.

Figure 3 is a block diagram for explaining the external call routing method in hardware in the satellite communication system according to an embodiment of the present invention.

4 is a flowchart illustrating a method for designating an external call path in a satellite communication system according to an embodiment of the present invention.

* Brief description of the main parts of the drawing

1: satellite 2: central control station

3A, 3B: Base station 11A, 11B: Public switched network

12A, 12B: Telephone 13A, 13B: Data Terminal

14A, 14B: Facsimile 21: Antenna

22: RF processing unit 23: IF combination distribution unit

24: SCPC channel unit (SCU) 30: network control unit

40: network management device

100: processor 101: dual-port RAM (DP-RAM)

102: service channel controller (SCC) 103: program storage unit

104: base station information storage unit 105: route number information storage unit

106: base station number information storage unit

In the satellite communication system according to the present invention for achieving the above object, an external call routing method is provided to a satellite communication system providing communication functions between subscribers by connecting a plurality of base stations coupled to a plurality of subscribers and a public switched network through satellites, respectively. In; When a predetermined call request signal is received from an arbitrary base station, a call type determination step of determining whether the corresponding call is an internal call or an external call, and when the call type is an internal call in the call type determination step, a series of internal call processing operations When the call type is an external call in the call processing step and the call type determining step, the relay line occupancy control is performed by searching for the base station number based on the relay line code and outputting the relay line occupancy request signal to the base station. Characterized in that it comprises a control step.

That is, according to the above, it is possible to minimize the load of the overall system by forming a call path through the base station of the location closest to the called party when the outgoing call attempt.

Next, the embodiment according to the present invention will be described in more detail.

FIG. 3 is a block diagram illustrating the external call routing method in hardware in a satellite communication system according to an embodiment of the present invention. FIG. 3 is a diagram illustrating the method of applying the present invention to the network controller 30 of FIG. A series of devices is added.

In the drawing, reference numeral 100 denotes a processor that controls the entire system and particularly executes a polling operation for each base station 3, and 101 denotes S by extracting packet information from a message applied from the SCPC channel unit 24. In addition to generating an ALOHA packet, the service channel controller generates and outputs a message of a TDM stream to the SCPC channel unit 24.

Also, reference numeral 102 denotes a dual port RAM, which is provided for data transmission and reception between the processor 100 and the service channel controller 101.

In addition, reference numeral 103 is a program storage unit for storing the operating program of the processor 100, 104 is received from each base station 3 by a polling operation performed based on a control signal of the processor 100, For example, the base station information storage unit 105 stores base station state information, such as a use state of a communication modem or an operation state of an arbitrary board mounted on the base station 3, and 105 denotes a trunk code (Trunk Code) of the called party. For example, a route number information storage unit 106 for storing a predetermined route number (e.g., a unique number of a relay line code connecting an arbitrary base station 3 and an arbitrary exchange in a public switched network) corresponding to a long distance area code; A base station number information storage unit for storing a unique identification code of the base station 3 corresponding to the route number stored in the route number information storage unit 105.

Here, when the processor 100 receives a series of called party numbers along with a predetermined call request signal from the calling internal call subscriber, the processor 100 determines whether the called party number is an internal call or an external call, and then calls the external call subscriber. The base station 3 selects an appropriate base station 3 based on the data recorded in the route number information storage unit 105 and the base station number information storage unit 106. Then, a predetermined relay line occupancy request signal is transmitted to the base station 3 so as to form a call path through the relay line.

On the other hand, the route number for the relay line code to be recorded in the route number information storage unit 105 and the base station number information storage unit 106 and the base station number for this route number when the system is initially activated in connection with the public switched network. It is initialized by the system administrator. In addition, the route number and the base station number can be added, deleted, or changed by the operator during operation.

Next, an external call routing method in the satellite communication system according to an embodiment of the present invention will be described with reference to the flowchart of FIG. 4.

First, when a predetermined call request signal is received from any internal call subscriber, the base station 3 receives a series of called subscriber numbers input from the calling party along with a predetermined call request signal through a random packet of the S-ALOHA channel. The control is sent to the central control station 3 (step ST401).

Then, upon receiving the called party number transmitted from the base station 3, the central control station 2 translates the called party number. That is, the processor 100 of the network control unit 30 searches for a number having a normal form with respect to the called party number received by driving control of a predetermined number translation processor (not shown), and the called subscriber number. If it is an internal call or an external call, the processor 100 controls to perform a series of internal call processing operations (step ST404).

That is, when the network controller 30 is an internal call result of the translation of the called party number currently requested in step ST403, the communication channel and communication modem available to the called base station 3 and the originating base station 3 are used. It is controlled to perform direct communication between both subscribers by allocating a.

On the other hand, if the result of the number translation in step ST403 is an external code (eg, when determined as a relay line code not used in the base station of the satellite communication system), the processor 100 reads the route number information storage unit 105. The predetermined route number is searched based on the relay line code of the called subscriber. Then, the base station number information storage unit 106 retrieves the unique number of the corresponding base station based on the retrieved route number (step ST405). Here, the route number is set when the system is initialized by the operator, and means a unique number of a trunk code of an arbitrary base station 3 and an arbitrary area-specific exchange period of the public switched network.

Then, the processor 100 controls the occupancy of the relay line by transmitting an occupancy request signal for the relay line connected to the public switching network to the destination base station 3 based on the retrieved base station number as described above (step ST406). Then, the base station 3 occupies an assigned relay line through a trunk interface port (not shown) coupled with the public switched network, and outputs a predetermined response signal thereto to the central control station 2.

That is, according to the above embodiment, it is possible to minimize the load of the overall system by forming a call path through the base station of the location closest to the called party when the outgoing call attempt.

In addition, this invention is not limited to the said Example, It can variously deform and implement within the range which does not deviate from the technical summary of this invention.

As described above, according to the present invention, in the satellite communication system, an internal call subscriber loads an air exchange network among a plurality of base stations coupled with a plurality of regional exchanges of the public exchange network when an outgoing call is attempted by an external call subscriber of a public switched network (PSTN). The external call routing method can be realized in a satellite communication system that can selectively designate a base station closest to the called subscriber to minimize the number of subscribers.

Claims (1)

A satellite communication system for providing a communication function between subscribers by connecting a plurality of base stations respectively coupled to a plurality of subscribers and a public switched network through satellites; When a predetermined call request signal is received from any base station, a call type determination step of determining whether the call is an internal call or an external call; An internal call processing step of performing a series of internal call processing operations when the call type is an internal call in the call type determination step; If the call type is an external call in the call type determination step, the relay line occupancy control step of controlling the occupancy of the relay line by searching for the base station number based on the relay line code and outputting the relay line occupancy request signal to the base station. External call routing method in satellite communication system.