KR0183277B1 - Effective channel searching method of satellite communication system - Google Patents

Abstract

The present invention eliminates unnecessary waste of time by avoiding redundant search for channels that are already in use in searching for available channels for channel assignment necessary for inter-subscriber communication in a satellite communication system. The present invention relates to a method for retrieving a usable channel of a satellite communication system and an apparatus thereof, comprising: a final acknowledgment channel position information storing means for storing position information of a last channel identified as an effective channel in a previous channel search, and a call from an arbitrary base station When there is a request, the channel information storage means searches for the unused communication channel based on the last search position information stored in the final confirmation channel position information storage means, and the position information of the last found channel is stored in the final confirmation channel position information storage means. In case of searching for a channel later, And control means for resetting the reference position of the search start point.

Description

Method for searching available channel of satellite communication system and 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 4 in FIG.

4 is a memory map diagram of the channel information storage unit 46 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 flowchart for explaining a usable channel search and channel allocation operation of a satellite communication system according to the present invention.

* 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: 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

50: network management system 60: processor

70: final confirmation channel location information storage unit

The present invention relates to a communication system using satellite, and in particular, in the search for a channel available for channel allocation necessary for communication between subscribers, unnecessary waste of time is avoided by avoiding duplicate search for a channel that is already in use. The present invention relates to a method and apparatus for searching available channels of a satellite communication system.

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. 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 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. An Orthohonal Mode Transducer (OMT) for separating and transmitting and receiving signals transmitted and received through a low noise amplifier (23) for low noise 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 3 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, the base station determines whether the other base station can communicate with each other based on the information obtained in the polling process. ) Is a network control unit that performs system control such that both base stations directly communicate with each other by allocating the "

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 network control unit 40, the reference numeral 41 in the drawing is a processor for controlling the call processing between the base station and, in particular, the entire system, 42 is the SCPC channel unit ( In addition to extracting the packet information (Rocket Packet) from the message applied in (26) to generate a S-ALOHA (Sloted ALOHA) packet, the time division multiplex (TDM) stream for the SCPC channel unit 31 is generated. This is a service channel controller (SCC) that generates and outputs messages.

Further, reference numeral 43 is 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 that stores a state of use of a communication channel allowed by a satellite.

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 conversion section 32 is converted to an uplink frequency signal of, for example, 14.5GHz. 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 GHz is transmitted through the quadrature mode converter 22 and the low noise amplifier 23 to the frequency down converter. The signal is applied to (24) and converted into an intermediate frequency signal of 70 MHz, and then applied to the SCPC channel unit 26 through the IF combination / distributor 25, demodulated and decoded, and then applied to the network controller 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 updated 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, 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, it is determined whether or not the communication state is possible, and if it is determined that the communication is possible, the communication channel currently available from the channel information storage unit 46 is examined.

4 is a diagram illustrating memory mapping of the channel information storage unit 46. The channel information storage unit 46 has a storage area corresponding to the number of communication channels allowable by satellites, and stores each of them. In the area, binary data of 0 or 1 is stored depending on whether a corresponding communication channel is used. The binary data is changed and set by the processor 41 according to the use state of the communication channel.

That is, when there is a call request from any base station, when the busy state of the communication channel is 1, the processor 41 checks the communication channel written with 0 in the channel information storage unit 46 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 channel. The communication channel is allocated by sending messages to both base stations, and at this time, the corresponding area of the channel information storage unit 46 corresponding to the allocated communication channel is set to 1 so that the communication channel can be assigned later. Will be referenced.

When the communication end message is transmitted from the calling base station after allocating the communication channel, the processor 41 transmits a message indicating that the communication is terminated to both base stations where the communication has been performed, and the channel information storage unit 46 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 channels from this point every time the channel is searched based on a specificly designated position such as the first address of the memory map shown in FIG. Since the caller tries to reconnect after disconnecting the phone because of a busy or bad track condition, the searched channel will be duplicated. There was a problem that it takes a relatively long time to find.

Therefore, the present invention has been created in view of the above circumstances, and stores and sets the address value in which the channel search was finally executed in the memory, and during the subsequent channel search, the search is performed from this set position and is already in use. An object of the present invention is to provide a method and apparatus for searching for a usable channel of a satellite communication system, which can prevent a redundant search from being unnecessarily detected for a channel identified as.

According to a first aspect of the present invention, there is provided a method for searching a usable channel of a satellite communication system, by combining a plurality of base stations, each of which is combined with a plurality of subscribers, through satellites to perform communication between arbitrary base stations. 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. If the most recent effective channel search is performed, the effective channel allocation final position information reading step for checking the final channel allocation final position, the available channel searching step for sequentially searching for available channels from the read channel position, and confirming as an available channel Channel assignment final location information update registration unit for updating registered channel location information And it is characterized in that is configured including a.

In addition, an apparatus for searching for a usable channel of a satellite communication system according to a second aspect of the present invention for realizing the above object comprises: a plurality of base stations coupled to a plurality of subscribers, a satellite for providing a call channel between each base station, and A satellite communication system having a central control station which allocates and controls a usable communication channel of a satellite to a base station having a call request, wherein the base station information storage means stores state information of each base station obtained by the central control station polling operation. And channel information storage means for storing the usage state of the communication channel allowed by the satellite, final confirmation channel position information storage means for storing position information of the last channel identified as an effective channel in a previous channel search, and from any base station. If there is a call request, the last retrieval stored in the final confirmation channel location information storage means Based on the location information, the channel information storage means searches for an unused communication channel and updates and registers the location information of the last searched channel in the final confirmation channel location information storage means. It characterized in that it comprises a control means for resetting the.

According to the present invention having the above-described configuration, it is possible to reduce the effective channel search time by avoiding duplicate search for a channel that is already in use in searching for a channel available for channel assignment necessary for inter-subscriber communication. It becomes possible.

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

FIG. 5 is a block diagram showing an apparatus for searching a usable channel 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. Omit.

In FIG. 5, reference numeral 70 denotes a final confirmation channel location information storage unit that stores location information of the last channel identified as a valid channel in a previous channel search, which is finally confirmed by the control of the processor 60 to be described later. The location information of the channel is stored, so that the initial location of the system is set as the initial location of the channel information storage unit 46.

On the other hand, reference numeral 60 denotes a processor that executes the monitoring function of the communication channel, which is a function of the processor 41 described in the third book, that is, when there is a call request from any base station, the channel information storage unit 46 is in an unused state. It checks the communication channel and assigns it to the calling base station and called base station so that both base stations can execute the communication directly through this allocated communication channel. The information is updated and registered in the final confirmation channel position information storage unit 70 so as to set a reference position of a search start point in the subsequent channel search.

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

In FIG. 5, when a call request message from any 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, address data of a channel finally confirmed in a previous channel search is read from the final acknowledgment channel position information storage unit 70 (step ST5). It is checked whether the channel of the address is available ('0') (step ST6).

On the other hand, if the channel 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 it finds an available channel (ST7). Step) Whenever the address of the search channel is changed, the address data of the final acknowledgment channel position information storage unit 70 is updated and registered (step ST8). When a valid channel is found, both the call base station and the called base station are located. A message is allocated to the call channel and the call channel is allocated (ST9).

Subsequently, when the use channel is allocated, the processor 60 sets the corresponding address data of the channel information storage unit 46 to '1' (step ST10), and determines whether the call termination message has been transmitted from the calling base station. When the call is ended (step ST11), when the call is ended, the call processing is completed by changing the address data of the channel information storage unit 46 to '0' (step ST12).

That is, according to the above embodiment, the address value of which channel search is finally performed is stored and set in the memory, and in the subsequent channel search, the search is performed from this set position, thereby unnecessary for the channel identified as being in use. Duplicate search can be prevented from occurring.

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, it is possible to avoid unnecessary waste of time by avoiding redundant search for channels that are already in use in searching for available channels for channel allocation necessary for inter-subscriber communication. A method and apparatus for searching for a usable channel of a satellite communication system can be realized.

Claims (2)

In a satellite communication system in which a plurality of base stations, each of which is combined with a plurality of subscribers, can be communicated through satellites to perform communication between arbitrary base stations, the base station that reads status information of a called base station for a call request of an arbitrary base station. Reading the information, the step of confirming the availability of the call of the base station, and if it is confirmed that the call is available, the effective channel allocation final position information reading to confirm the channel allocation final position where the most recent effective channel search was performed And an available channel search step of sequentially searching for available channels from the read channel position, and a channel assignment final position information update registration step of updating and registering channel position information identified as available channels. Method of searching available channel of satellite communication system. A satellite communication system having a plurality of base stations, each of which is combined 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 the available call channels of the satellites to the base stations with call request. The central control station is effective in base station information storage means for storing state information of each base station obtained by a polling operation, channel information storage means for storing a use state of a communication channel permitted by satellite, and previous channel search. Final confirmation channel position information storage means for storing the position information of the last channel identified as a channel, and channel information based on the last search position information stored in the final confirmation channel position information storage means when a call request is received from any base station. Search the unused communication channel in the storage means, and And a control means for resetting the reference position of the search start point in the subsequent channel search by updating and registering the value information in the final confirmation channel position information storage means. .