KR0183268B1 - An usable modem searching method of satellite communication system - Google Patents

Abstract

In the present invention, in searching for a modem available for the modem (SCU) allocation required for inter-subscriber communication in a satellite communication system, it is possible to avoid redundant search for a modem that has been identified as being in use, thereby eliminating unnecessary waste of time. The present invention relates to a method and apparatus for searching for a modem available in a conventional satellite communication system, and to a plurality of base stations each coupled with a plurality of subscribers, a satellite for providing a call channel between each base station, and a base station with a call request. In a satellite communication system having a central control station for assigning and controlling a modem (SCU), the position information of the last modem identified as a valid modem in a previous modem search is stored, and the final acknowledgment when a call request is received from an arbitrary base station. Read modem location information and use the unused modem (SCU) from the last search position. In this case, it is characterized in that it comprises a step and means for resetting the reference position of the search start point in the subsequent modem search by updating and registering the position information of the last found modem as the last confirmed modem position information. .

Description

Method of searching for available modem (SCU) in satellite communication system and its device

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.

3 is a block diagram showing the configuration of the network controller 40 in FIG.

4 is a memory map diagram of the modem information storage unit 47 in FIG.

5 is a block diagram showing the configuration of a network controller 40 in a satellite communication system according to an embodiment of the present invention.

6 is a flow chart for explaining the operation of the modem (SCU) search and modem allocation in the satellite communication system according to the present invention.

7 is a block diagram showing the configuration of the network controller 40 'in the satellite communication system according to the second embodiment of the present invention.

8 is a memory map diagram of the modem state storage unit 48 shown in FIG.

* Explanation of symbols for main parts of the drawings

1: satellite 2: central control station

3A, 3B: base station 11A, 11B: switchboard

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

14A, 14B: Facsimile 21: Antenna

22: orthogonal mode converter 23: low noise amplifier

24: frequency down converter 25: intermediate frequency combination / distribution unit

26, 31: SCPC channel unit 32: frequency up converter

33: high power amplifier 40, 40 ': network control unit

41: processor 42: service channel controller

43: Dual Port RAM 44: Program Storage

45: base station information storage unit 46: channel information storage unit

47: modem information storage unit 48: modem state storage unit

50: network management system 60: processor

70: final confirmation modem location information storage unit

The present invention relates to a communication system using satellites, and in particular, in searching for a modem available for modem (SCU) allocation required for inter-subscriber communication, unnecessary duplication can be avoided for a modem that has been identified as being in use. The present invention relates to a method and apparatus for searching for a modem that can be used in a satellite communication system that can eliminate a waste of time.

Recently, with the rapid development of communication technology, satellite communication, which enables subscribers who are located at remote sites to make calls through satellites, has become increasingly common. Since such satellite communication does not require a separate signal line for a call, It is mainly used as a long distance communication between countries or as a communication method in a mountainous country such as Korea.

In the above-mentioned satellite communication, there are two types of PAMA (Pre Assignment Multiple Access) method for allocating communication channels for each subscriber according to the channel allocation method and Demand Assignment Multiful Access (DAMA) method for allocating communication channels according to the subscriber's request. In general, in the satellite communication system for communication between subscribers, many DAMA methods are adopted in consideration of the cost and the 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). Communication function between the various terminals through data transmission and reception with the central control station 2 as well as an interface function for terminals such as data terminals 13A and 13B and facsimile 14A and 14B, such as a computer. The base station that provides.

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.

In the above-described configuration, the central control station 2 transmits a control message through a service channel in a normal state and then communicates the state of each base station 3 based on a response message transmitted from the base station 3. 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. When the communication state is available, the available traffic channels T of the satellites are allocated to both base stations 3A and 3B so that the 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 end signal is applied through the service channel 2 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 FIG. 2, reference numeral 21 is an antenna for transmitting / receiving an satellite 1, an uplink signal, and a downlink signal, and 22 is an antenna 22 using frequency polarization characteristics. Orthogonal Mode Transducer (OMT) for separating and transmitting and receiving signals transmitted and received through 23, 23 is a low-noise amplifier for low-noise amplifying downlink frequency signals of 12.25 ~ 12.75 GHz input through the orthogonal mode converter (22) Low Noise Amplifier (LNA), 24 is a frequency down converter (DC) for converting a frequency signal applied through the low noise amplifier 23 into an intermediate frequency signal IF of 70 MHz, for example.

In addition, reference numeral 25 separates and outputs the intermediate frequency signal IF applied from the frequency down converter 24 into a plurality of intermediate frequency signals, and also describes a Single Channel Per Carrier (SCP) channel unit to be described later. SCU: an intermediate frequency combiner / distributor (IF C / D: IF combiner / distributer) which combines and outputs an intermediate frequency signal applied from 31), and 26 is an intermediate applied from this intermediate frequency combiner / distributer 25 An SCPC channel unit that demodulates, decodes, and outputs a frequency signal, wherein the intermediate frequency combination / distributor 25 is employed for system scalability when using a plurality of SCPC channel units.

Further, reference numeral 31 denotes an SCPC channel unit for encoding, modulating and outputting a message output from the network controller 40 to be described later, and 32 denotes an IF signal of 70 MHz applied from the IF combination / distributor 25. For example, a frequency upconverter (UC) for converting the microwave into a microwave of 14.0 to 14.5 GHz to generate an uplink frequency signal, 33 is a high output amplifier for amplifying the uplink frequency signal output from the frequency upconverter 32 ( HPA: High Power Amplifier.

And, reference numeral 40 is a polling function that checks the state of each base station 3 based on a response message transmitted from the base station after transmitting a control message to each base station 3 through the SCPC channel unit 26. If there is a call request from a specific base station, it is determined whether the other base station is in a communication state based on the information obtained in the polling process. ) Is a network control unit that performs system control such as assigning a modem to both base stations so that both base stations can directly communicate with each other.

In addition, reference numeral 50 is a network management system for the system administrator to manage the network control unit 40 to manage the overall network of the satellite communication system.

On the other hand, Figure 3 is a schematic diagram showing the configuration of the above-described network control unit 40, reference numeral 41 in the drawing is a processor that controls the entire system, in particular call processing between the base station, 42 is the SCPC channel A packet information is extracted from a message authorized by the unit 26 to generate a slotted packet (S-ALOHA), and a time division multiplex (TDM) stream for the SCPC channel unit 31 is generated. Service Channel Controller (SCC) that generates and outputs messages from

Reference numeral 43 is also a dual port RAM, which is provided for data transmission and reception between the processor 41 and the service channel controller 42.

Reference numeral 44 is a program storage unit for storing the operation program of the processor 44, and 45 is a base station information storage unit for storing state information of each base station obtained by the polling operation of the network processor 40. Is a channel information storage unit for storing the use state of the communication channel allowed by the satellite, 47 is a modem information storage unit for storing information on the modem use state of each base station.

Next, the operation of the satellite communication system having the above configuration will be described.

In the normal state, the network controller 40 of FIG. 2 performs a polling operation to check the state of each base station.

That is, the processor 41 of the network control unit 40 writes packet data for checking the state of each base station in the dual port RAM 43, and the service channel controller 42 writes in the dual port RAM 43. After reading the written packet data, the TDM stream generates a message and outputs it to the SCPC channel unit 31.

Then, the SCPC channel unit 31 converts the message into an intermediate frequency signal of 70 MHz by encoding and modulating the message, and outputs the intermediate frequency signal. The intermediate frequency signal is combined for each frequency in the IF combining / distributing unit 25, The frequency increasing converter 32 converts the uplink frequency signal of, for example, 14.5 GHz. The uplink frequency signal is output through the high power amplifier 33, the quadrature mode converter 22, and the antenna 21, and then transmitted to each base station 3 through the satellite 1 in FIG. .

Meanwhile, the response message received from the base station 3 through the satellite 1 to the antenna 21, that is, the downlink frequency signal of 12.25 GH is transmitted through the orthogonal mode converter 22 and the low noise amplifier 23 through the frequency down converter. It is applied to (24) is converted into an intermediate frequency signal of 70 MHz, then applied to the SCPC channel unit 26 through the IF combination / distribution unit 25, demodulated and decoded and then applied to the network control unit 40 .

In addition, the network controller 40 extracts packet information from the message to which the service channel controller 42 is applied to generate an S-ALOHA packet, and then writes the packet information into the dual port RAM 43. The packet data is read from the port RAM 43, and the base station information storage unit 45 is renewed and registered to retain the state information for each base station.

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

On the other hand, if there is a call request from any base station to any other base station during the above-described polling operation, that is, a message indicating the call request from the satellite 1 is received through the antenna 21 of FIG. When the packet data is input from the service channel controller 42 of the network controller 40, the processor 41 first reads the state information of the base station called from the base station information storage unit 45, and the base station currently communicates. In this case, if it is determined that the communication is possible, the channel information storage unit 46 and the modem information storage unit 47 are checked to determine the currently available communication channel and modem (SCU). .

4 is a diagram showing memory mapping of the modem information storage unit 47. The modem information storage unit 47 has a storage area corresponding to the number of modems in each base station, and is stored in each storage area. Binary data of 0 or 1 may be stored depending on whether a corresponding communication modem is used. The binary data is changed and set by the processor 41 according to the use state of the communication modem.

That is, when there is a call request from any base station, when the busy state of the communication modem is 1, the processor 41 checks the communication modem written with 0 in the modem information storage unit 47 and calls it with the calling base station. By assigning the allocated base stations, both base stations can perform communication directly through the assigned communication modem. On the other hand, this communication modem is allocated by sending a message to both base stations. At this time, the corresponding area of the modem information storage unit 47 corresponding to the allocated communication modem is set to 1, so that the communication modem is assigned at a later time. Will be referenced.

When the communication end message is transmitted from the calling base station after allocating the communication modem, the processor 41 transmits a message indicating that the communication is terminated to both base stations where the communication has been performed, and the modem information storage unit 47 transmits a message. The communication end process is executed by setting the area to 0 again.

In the above-described satellite communication system, however, the processor 41 sequentially checks the available modems from this point in every search based on a specifically designated location such as the first address of the memory map shown in FIG. If the user who is calling the phone hangs up and tries to reconnect because of a busy or bad track condition, the user will be able to use the duplicated search for the modem that is already in use. The problem was that it took a relatively long time to find a modem.

Accordingly, the present invention has been made in view of the above circumstances, and the address value of the modem search (SCU), which has been finally executed, is stored and set in the memory. An object of the present invention is to provide a method and apparatus for retrieving a usable modem (SCU) of a satellite communication system which can prevent duplication detection from occurring unnecessarily for a modem identified as being in use.

Modem retrieval method of the satellite communication system according to the first aspect of the present invention for realizing the above object is to combine a plurality of base stations, each of which is combined with a plurality of subscribers via satellite to perform communication between any base station In a satellite communication system, a base station information reading step of reading out status information of a called base station in response to a call request of an arbitrary base station, a call availability checking step of confirming whether a corresponding base station can be called, and a call availability state is confirmed. Reads the valid modem assignment final location information to identify the last assigned modem location where the most recent valid modem (SCU) search was performed, and then the available modem search step to sequentially search for available modems from the read modem location. Update the modem assignment final location information to update and register the modem location information identified as the modem Characterized in that it comprises a registration step.

In addition, a modem searching apparatus for a satellite communication system according to a second aspect of the present invention for realizing the above object comprises: a plurality of base stations each coupled with a plurality of subscribers, a satellite for providing a communication channel between each base station, A satellite communication system having a central control station for assigning and controlling a modem (SCU) usable for a base station with a call request, wherein the central control station stores base station information in which state information of each base station obtained by a polling operation is stored. Means, a modem information storage means for storing a state of use of the communication modem, a final confirmation modem position information storing means for storing position information of the last modem identified as a valid modem in a previous modem search, and a call request from any base station In this case, the modem information is stored on the basis of the last search position information stored in the final confirmation modem position information storage means. Control means for retrieving the unused modem (SCU) in the means and resetting the reference position of the starting point of the search in the subsequent modem search by updating and registering the last found modem location information with the final confirmation modem location information storage means. Characterized in that configured to include.

That is, according to the present invention having the above-described configuration, it is possible to avoid the duplicate search for the modem (SCU) that is already in use in searching for a modem available for the modem (SCU) allocation necessary for inter-subscriber communication. Therefore, the effective modem search time can be shortened.

Hereinafter, an embodiment according to the present invention will be described with reference to the drawings.

FIG. 5 is a block diagram showing an effective modem searching apparatus of a satellite communication system according to an embodiment of the present invention. In FIG. 5, parts having substantially the same functions as those of FIG. 4 are denoted by the same reference numerals, and detailed description thereof is omitted. do.

In FIG. 5, reference numeral 70 denotes a final confirmation modem location information storage unit which stores location information of the last modem identified as a valid modem in a previous modem (SCU) search, which is controlled by the processor 60 to be described later. The position information of the finally confirmed modem is stored, so that it is set as the initial position of the modem information storage unit 47 during the initial operation of the system.

On the other hand, reference numeral 60 denotes a processor that executes the monitoring function of the communication modem, which is a function of the processor 41 described in the third book, that is, when there is a call request from an arbitrary base station, the modem information storage unit 47 is in an unused state. It checks the communication modem and assigns it to the calling base station and called base station so that both base stations can execute communication directly through the assigned communication modem. The information is updated and registered in the final confirmation modem position information storage unit 70 so as to set the reference position of the search start point during the subsequent modem search.

Next, the operation of the system having the above-described configuration will be described in more detail using the prochart shown in FIG.

In FIG. 5, when a call request message from an arbitrary base station is input to the processor 60 through the service channel controller 42 (step ST1), the processor 60 first calls from the base station information storage unit 45. The status information of the base station to be requested, that is, the called base station is read (step ST2) to determine whether the base station is in a state where a current call is possible (step ST3).

When the base station called in step ST3 is determined to be in a callable state, the address data of the modem finally confirmed in the previous modem search is read from the final acknowledgment modem position information storage unit 70 (step ST5). It is checked whether the modem of the corresponding address is available ('0') (ST6 step).

On the other hand, if the modem of the corresponding address is already in use and is not available, the processor 60 increases the address by '1' and repeatedly executes a search operation until a modem is found available (ST7). Step) Whenever the address of the search modem is changed, address data of the final acknowledgment modem location information storage unit 70 is updated and registered (step ST8). When a valid modem is found available, both the call base station and the called base station are located. Sends a message to and assigns a call modem (ST9 step).

Subsequently, when the modem is used, the processor 60 sets the corresponding address data of the modem information storage unit 47 to '1' (step ST10), and determines whether the call termination message has been transmitted from the calling base station. In step ST11, the call is terminated by changing the address data of the modem information storage unit 47 to '0'.

That is, according to the above embodiment, the address value of the modem search which has been finally performed is stored and set in the memory, and when the modem is searched later, the modem is confirmed to be in use by executing the search from this set position. It is possible to prevent unnecessary duplicate search from occurring.

On the other hand, the above-described effective modem search procedure is based on the assumption that the device configuration of each base station is operating normally, but in reality, there may be a partial malfunction in any part of the satellite communication system which is complicated and extensive. Therefore, even in the field of managing effective modem (SCU), more efficient operation plan is needed.

7 is a block diagram showing a second embodiment of the present invention constructed in view of the above circumstances. In comparison with the configuration of the first embodiment shown in FIG. 5, reference numeral 48 denotes a modem in which the processor 60 of the central control station 2 is reported from a processor (not shown) of the subordinate base station during polling. (SCU) A modem state storage unit for identifying and separately managing a modem (SCU) showing normal operation based on state information. In general, the number of modems (SCU) that a single base station can accommodate to the maximum is 32. In view of the above, in the case of the satellite communication network composed of N base stations, memory mapping therein is illustrated in FIG. 8.

That is, for example, when the modem (SCU) that is abnormally operated in the No. 2 SET among the modems (SCU) of the N subordinate base stations is identified, the processor (not shown) of the corresponding base station receives the central control station ( This is reported to the processor 60 side of 2), the processor 60 of the central control station 2 based on this data of the corresponding modem address of the modem state storage unit 48 as illustrated in FIG. Is set to '1' to exclude the corresponding modem (SCU) first when assigning a modem (SCU) by call setup request.

Therefore, according to the second embodiment, the processor 60 of the central control station 2 first checks the modem state storage unit 48 when there is a call setup request. By selecting the modem (SCU), that is, the modem in the normal operating state, and later setting the effective modem (SCU) in the same manner as described in the above-described embodiment 1, it is possible to perform more efficient modem (SCU) management .

On the other hand, the present invention is not limited to the above embodiments and can be implemented in various modifications without departing from the technical rights of the present invention.

As described above, according to the present invention, in searching for a modem (SCU) that can be used for modem assignment required for inter-subscriber communication, unnecessary waste of time can be avoided by avoiding duplicate search for a modem that is already in use. A method and apparatus for searching for a usable modem in a satellite communication system that can be eliminated can be realized.

Claims (4)

In a satellite communication system in which a plurality of base stations, each of which is combined with a plurality of subscribers, are combined through satellites to perform communication between arbitrary base stations, a base station for which a called base station reads status information for a call request of an arbitrary base station. Validation step of reading information, checking whether the base station can be called or not, and if it is confirmed that the call is possible, the effective modem allocation final confirmation of the final position of the modem allocation where the most recent valid modem (SCU) search was performed A location information reading step, a usable modem search step of sequentially searching for available modems from the read modem position, and a modem assignment final location information update registration step of updating and registering modem location information identified as an available modem. A method for searching a usable modem of a satellite communication system characterized by the above-mentioned. The satellite communication system of claim 1, further comprising a normal modem checking step for screening a normal operation modem (SCU) first before executing the effective modem allocation final position information reading step. How to find a modem. A satellite communication system having a plurality of base stations, each coupled with a plurality of subscribers, a satellite for providing a call channel between each base station, and a central control station for allocating and controlling a modem (SCU) usable for a base station with a call request. The central control station includes: base station information storage means for storing state information of each base station obtained by a polling operation, modem information storage means for storing a use state of a communication modem, and the last confirmed as a valid modem in a previous modem search. Unused state in the modem information storage means starting from the final acquiring modem position information storing means for storing the position information of the modem, and the last search position information set in the final acquiring modem position information storing means when a call request is received from any base station. Search for modem (SCU) and locate the last found modem And a control means for resetting the reference position of the search start point in the subsequent modem search by updating and registering the data in the storage storage means. [4] The satellite communication system of claim 3, further comprising a modem state storage unit for storing operation state information indicating whether the modem is in normal operation in order to separately manage the normal operation modem (SCU). Modem Finder.