KR100198748B1 - Standard time correcting device in satellite communication system - Google Patents

Abstract

The present invention provides a reference in satellite communication in which a reference time is periodically input from a network management system (DOP) in a central control station and the time in the central control station is corrected based on this reference time to match the time of the entire network. A time correction apparatus, comprising: a base station coupled to a plurality of subscribers, and a satellite communication system having a central control station for controlling communication between base stations having a call request, wherein the central control station is configured to provide a reference time of a network. Network reference time generation means for generating and periodically outputting itself, reference time storage means for storing the reference time, timer means for counting time data stored in the reference time storage means, and the reference time storage means Net output from the time data and network reference time generating means of And control means for updating and storing the time data of the reference time storage means to the network reference time data if the work reference time data do not match.

Description

Reference time correction device in satellite communication system

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

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 block diagram showing the configuration of a reference time correction apparatus in a satellite communication system according to an embodiment of the present invention.

FIG. 5 is an operation flowchart for explaining the operation of the apparatus of 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 60: network management system

70: processor

71: Complementary Metal Oxide Semiconductor (CMOS)

72: first timer 73: second timer

74: temporary time storage unit 75: current time storage unit

76: time plate

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication system using satellites, and in particular, receives a reference time periodically from a network management system (DOP) in a central control station and corrects the time in the central control station based on the reference time. The present invention relates to a reference time correction device in satellite communication that can be matched.

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 by 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 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 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) 23 for separating and inputting and receiving signals transmitted and received through a low noise amplifier for low-noise amplifying downlink frequency signals of 12.25-12.75 GHz input through the Orthogonal Mode Transducer 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 70 MHz IF signal applied from the IF combination / distributor 25. For example, a frequency up-converter (UC) for converting microwaves from 14.0 to 14.5 GHz to generate an uplink frequency signal, and a high output amplifier (HPA) for amplifying an uplink frequency signal output from the frequency up-converter 32. : 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 by allowing both base stations to directly communicate with each other.

In addition, reference numeral 60 denotes a network management system for managing the overall network of the satellite communication system by the system administrator to manage the network control unit 40.

3 is a diagram schematically illustrating the configuration of the network controller 40 described above. In FIG. 3, reference numeral 41 denotes the overall control of the system, and in particular, the same time between the central control station 2 and the base station 3. 42 is a processor for controlling the matching to be consistent, and extracts packet information from the message applied from the SCPC channel unit 26 to generate an S-ALOHA (Sloted ALOHA) packet, and the SCPC channel unit A service channel controller (SCC) that generates and outputs a message of a time division multiplex (TDM) stream with respect to 31.

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 controller 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, a message of the TDM stream is generated and outputted 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 by frequency in the IF combination / distributor 25 and then frequency. Increment converting section 32 is converted to an uplink frequency signal of, for example, 14.5 GHz. The uplink frequency signal is outputted 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 GHz 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, and 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 .

Subsequently, the network controller 40 extracts packet information from the message to which the service channel controller 42 is applied, generates an S-ALOHA packet, and 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 based on the packet data, thereby retaining state information for each base station.

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

On the other hand, when there is a call request for any other base station from any 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). .

In addition, in the communication system using the satellite communication as described above, the central control station (2) itself counts the reference time and transmits it to each base station (3) and polling to check the state of the base station (3). Each base station 3 performs mutual communication such as outputting a corresponding response message according to the polling message to the central control station 2.

At this time, in order to deal with problems such as call setup and release or billing processing without confusion, the time counted by each base station 3 must not only coincide, but the reference time of this base station and the central control station 2 must also be completely coincident. .

Accordingly, the present invention was created in view of the above circumstances, and periodically receives a reference time from a network management system (DOP; DAMA Operation Processor) in the central control station and corrects the time in the central control station based on the reference time. It is an object of the present invention to provide a reference time correction device in a satellite communication system that enables the time of the entire network to match.

A reference time correction apparatus in a satellite communication system according to the present invention for realizing the above object is a satellite communication system having a base station coupled with a plurality of subscribers, and a central control station for controlling communication between base stations with call requests. The network control unit generates a reference time of the network by itself and periodically outputs the network reference time generating means, reference time storing means for storing the reference time, and time data stored in the reference time storing means. Timer means for counting and updating and storing the time data of the reference time storage means as network reference time data if the time data of the reference time storage means and the network reference time data output from the network reference time generating means do not match. Characterized in that it comprises a control means do.

That is, according to the present invention having the above-described configuration, the time of the central control station 2 and each base station 3 can be matched by correcting the reference time output from the central control station 2 to each base station 3. Will be.

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

FIG. 4 is a block diagram showing a reference time correction apparatus in a satellite communication system according to an embodiment of the present invention. In FIG. 4, parts having substantially the same functions as those of FIG. 3 are denoted by the same reference numerals. Omit.

In the figure, reference numeral 71 denotes a Clementary Metal Oxide Semiconductor (CMOS) for storing a reference time input from the network management system 60, and reference numeral 72 counts the current time based on the time data of the CMOS 71. As a first timer for performing this, time data of the CMOS 71 is counted and updated according to the counting operation of the first timer 72.

Reference numeral 73 denotes a second timer for performing a counting operation according to a control signal of the processor 70, which will be described later, and outputting a signal of a predetermined level according to predetermined time data, and reference numeral 74 denotes a network management system 60. The temporary time storage unit 75 for temporarily storing the reference time data inputted from the reference time, 75 stores the time data updated by the counting operation of the first timer 72 according to a control signal of the processor 70 to be described later. As the current time storage unit, this stores, for example, time data output from the CMOS 71 every 100 ms. Also, reference numeral 76 denotes a time judging unit for comparing and judging time data input from the temporary time storage unit 74 and the current time storage unit 75 to output a predetermined result signal.

Reference numeral 70 denotes a processor that executes a correction function of the reference time, which is a function of the processor 41 described in FIG. 3, that is, when a call request is received from an arbitrary base station, the calling base station and the called base station call the communication modem. In addition to executing a call control function such as allowing communication to be performed directly, the reference time input from the network management system 60, for example, every 60 seconds, is compared with existing time data, and then based on the result. The processor controls a function of ignoring a newly input reference time or updating and storing time data of the CMOS 71.

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

First, when the central control station 2 operates for the first time, the processor 70 of the network control unit 40 initializes the CMOS 71, the current time storage unit 75, and the like (step ST11).

Subsequently, when a reference time is input from the network management system 60 (step ST12), the processor 70 stores the reference time in the CMOS 71 and the current time storage unit 75 (step ST13). ).

Then, the processor 70 executes control of the counting operation by resetting the first and second timers 72 and 73 (step ST14).

Subsequently, the second timer 73 performs a counting operation, for example, when 100 ms is reached, a signal of a predetermined level is output to the processor 70. In this case, the processor 70 of the first timer 72 According to the counting operation, the time data updated and stored in the CMOS 71 is read out and stored in the present time storage unit 75 (steps ST15 and ST16).

Here, the time data stored in the current time storage unit 75 in the steps of ST15 and ST16 are output to the SCC 42 of FIG. 3 according to the control signal of the processor 70 and then through the antenna 21. By sending to each base station 3, the time of the whole network is matched.

Subsequently, the processor 70 reads the time data from the CMOS 71 every 100 ms and stores the time data in the current time storage 75, and when a new reference time is input from the network management system 60 (step ST17). In addition to storing the reference time in the temporary time storage unit 74, it is determined whether or not it matches the time data stored in the current time storage unit 75 (steps ST18 and ST19).

Then, when the processor 70 receives a signal of a predetermined level as the two time data are not matched from the time determiner 76, the processor 70 proceeds to step ST13, the CMOS 71 and the current time storage unit 75. Sub-steps such as updating and storing the time data.

However, if a time signal is received from the time judging unit 76 according to the coincidence of the two time data, the network management system 60 ignores the newly input reference time and proceeds to step ST15 to perform the second step. The operation of the lower step is executed based on the input signal input from the timer 73 (step ST20).

That is, according to the embodiment, the time of the central control station 2 is corrected and the reference time is sent to each base station 3 so that the time of the entire network can be matched.

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, the reference time is periodically input from the network management system (DOP) in the central control station, and the reference time in the central control station is corrected based on this reference time to match the time of the entire network. It is possible to realize the reference time correction device in the satellite communication system.

Claims (2)

In a satellite communication system having a base station coupled with a plurality of subscribers, and a central control station for controlling communication between base stations having a call request, the central control station generates a reference time of the network by itself and periodically outputs it. Network reference time generating means, reference time storing means for storing the reference time, timer means for counting time data stored in the reference time storing means, time data and network reference time of the reference time storing means And control means for updating and storing the time data of the reference time storage means to the network reference time data if the network reference time data outputted from the generating means does not match. 2. The apparatus according to claim 1, further comprising a current time storing means for storing predetermined time data, and a counter means for executing a predetermined counting operation, wherein said control means is based on a signal output from said counter means. And reading out the time data of the reference time storing means and storing the time data in the current time storing means and transmitting the time data to the base stations.