KR100205654B1 - In a satellite communication system, - Google Patents

Abstract

When a central control station wants to receive data related to network operation and maintenance from a base station, a predetermined packet (a packet or a time slot) constituting a Slotted Aloha channel, which is a transmission channel, (SDN) for managing a service data network (SDN) composed of a TDM channel between a central control station and a base station and an S-ALOHA channel, An administrator, a reservation packet information storage unit for indicating a reserved allocation state of reservation packets of the S-ALOHA channel with a predetermined flag, a frame number storage unit for storing frame number data of reservation packets currently being transmitted from the base station, An offset data storage unit for storing predetermined added numerical data and time slot number data input from the apparatus Wherein the SDN manager adds a summation numeric data to the frame number data of the frame number storage unit when the summation numeric data is inputted together with a message requesting reservation allocation of a reservation packet from an arbitrary device to calculate frame number data And reserving a reserved packet based on the number of timeslots.

Description

In a satellite communication system, a reserved packet allocation apparatus

The present invention relates to a communication system using a satellite, and in particular, when a central control station receives data related to network operation and maintenance from a base station, the central control station transmits a predetermined packet (hereinafter referred to as " packet ") constituting a Slotted Aloha channel (Reservation packet) to a reserved packet allocation apparatus in a satellite communication system that can prevent loss of data.

In recent years, with the rapid development of communication technology, satellite communication that enables subscribers located at a remote place to make calls through a satellite is gradually becoming common. Such satellite communication is useful for long distance communication between countries, or communication method of a mountainous country like Korea because a separate signal line is not required for communication.

In the above-described satellite communication, a PAM (Pre-Assignment Multiple Access) scheme for allocating each communication channel for each subscriber according to the channel allocation scheme and a Demand Assignment Multiple Access (DAMA) scheme for allocating a communication channel according to a subscriber's request In general, in the satellite communication system for communication between subscribers, the DAMA system is adopted in consideration of the price and effectiveness of the communication channel.

FIG. 1 is a block diagram showing an overall system configuration of a general satellite communication system according to a DAMA scheme.

In FIG. 1, reference numeral 1 denotes a satellite having a plurality of communication channels, reference numeral 2 denotes a central control station for controlling the entire satellite communication system, reference numerals 3A and 3B denote data terminals such as exchangers, And provides a communication function between various terminals through data transmission / reception with the central control station 2 in addition to having an interface function with respect to the terminal.

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

In the above configuration, the central control station 2 transmits a control message through the service channel in a normal state, and then, based on the response message transmitted from the corresponding base station 3, And performs a polling function for checking the available capacity or the use state 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 or not the base station 3B can communicate with the base station 3B based on the information obtained in the polling process And if the communication is enabled, the available traffic channels T of the satellites are allocated to the base stations 3A and 3B so that the base stations 3A and 3B can directly communicate with each other.

Then, when the communication end signal is applied via the service channel S from the base station 3A in which the communication between the base stations 3A and 3B has been completed and the communication request has been made, the central control station 2 transmits The communication end process is executed to release the traffic channel T that was provided to both the base stations 3A and 3B.

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

Reference numeral 21 in FIG. 2 denotes an antenna for transmitting / receiving an uplink signal and a downlink signal with the satellite 1 and reference numeral 22 denotes an antenna for transmitting / receiving an uplink signal and a downlink signal through the antenna 21 An orthogonal mode transducer (OMT) 23 for separately inputting and outputting signals to be transmitted and received, a low noise amplifier 23 for low-noise amplifying a downlink frequency signal of, for example, 12.25 to 12.75 GHz inputted through the orthogonal mode converter 22 LNA (Low Noise Amplifier), and 24 is a frequency down converter (DC) for converting a frequency signal applied through the low noise amplifier 23 to an intermediate frequency signal IF of, for example, 70 M Hz.

Reference numeral 25 denotes a frequency division multiplexer for separating and outputting an intermediate frequency signal IF applied from the frequency down converter 24 to a plurality of intermediate frequency signals and outputting a single channel per channel (SCPC) channel unit (IF C / D: IF Combiner / Distributor) 26 for outputting an intermediate frequency signal applied from the intermediate frequency combining / distributing unit 25, Demodulates, decodes and outputs the frequency signal, and encodes and modulates a message output from the network control unit 40, which will be described later, and outputs the message.

Here, the intermediate frequency combining / distributing unit 25 is employed for system scalability when a plurality of SCPC channel units are used.

Reference numeral 27 denotes a frequency up-converter (UC) for converting an IF signal of 70 MHz applied from the IF combining / distributing unit 25 into a microwave of, for example, 14.0 to 14.5 GHz to generate an uplink frequency signal. And 28 is a high power amplifier (HPA) for amplifying an uplink frequency signal output from the frequency up converter 27.

Reference numeral 40 indicates a state of each base station 3 based on a response message transmitted from the corresponding base station after transmitting a control message to each base station 3 through arbitrary SCPC channel units 261 to 26N If there is a call request from a specific base station, it is determined whether the other base station is capable of communicating based on the information obtained in the polling process. If the communication is available, the available traffic of the satellite A network controller for performing system control such that both base stations can directly perform mutual communication by assigning a channel T and a modem to both base stations.

Reference numeral 50 denotes a network management system for the system manager to manage the overall network of the satellite communication system by managing the network control unit 40.

3 is a block diagram schematically showing the configuration of the network control unit 40. Reference numeral 41 denotes a processor for controlling the entire system of the central control station 2 and reference numeral 42 denotes a SCPC channel unit 26 ALOHA (Slotted ALOHA) packet, and transmits a message of a TDM (Time Division Multiplex) stream to the SCPC channel unit 26. In addition, (SCC: Service Channel Controller) for generating and outputting a service channel controller.

Reference numeral 43 denotes a dual port RAM which is provided for data transmission and reception between the processor 41 and the service channel controller 42 and reference numeral 44 denotes a dual port RAM for the central control station 2 and the base station 3 (SDN Manager) that manages the service network (SDN) which is a communication channel.

The SDN manager 44 manages a common control channel (SDN) for centrally managing the satellite channels, which are resources in a limited call, so that a plurality of users can share them.

Reference numeral 45 denotes a program storage unit in which an operation program of the processor 41 is stored. Reference numeral 46 denotes a base station information storage unit in which status information of each base station obtained by the polling operation of the network processor 41 is stored. Is a channel information storage unit for storing a usage state of a communication channel allowed by the satellite.

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

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

That is, the processor 41 of the network control unit 40 writes the packet data for checking the status of each base station into the dual port RAM 43, and the service channel controller 42 controls the dual port RAM 43 Reads the written packet data, generates a message of a TDM stream, and outputs the message to the SCPC channel unit 26.

Then, the SCPC channel unit 26 encodes and modulates the message to convert it into an intermediate frequency signal of, for example, 70 MHz, and outputs the intermediate frequency signal. The intermediate frequency signal is combined by frequency in the IF combining / distributing unit 25, And is converted into an uplink frequency signal of, for example, 14.5 GHz by the frequency increase converter 27. The uplink frequency signal is outputted through the high-power amplifier 28, the orthogonal mode converter 22 and the antenna 21, and then transmitted to each base station 3 through the satellite 1 in FIG. 1 .

The downlink frequency signal of 12.25 GHz received from each base station 3 via the antenna 1 through the antenna 21 is transmitted through the orthogonal mode converter 22 and the low noise amplifier 23, Converted into an intermediate frequency signal of 70 MHz and applied to the SCPC channel unit 26 through the IF combining / distributing unit 25 to be demodulated and decoded and then supplied to the network control unit 40 .

The network controller 40 extracts the packet information from the message to which the service channel controller 42 is applied and generates a slotted aloha packet and writes the packet into the dual port RAM 43. The processor 41 transmits the dual It reads the packet data from the port RAM 43 and updates and registers the base station information storage unit 46 based on the packet data to hold status information for each base station.

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

When there is a call request from another base station to the other base station during the polling operation, the processor 41 first reads out the status information of the base station, which is called from the base station information storage unit 46, It is determined whether communication is currently possible. If it is determined that communication is possible, the channel information storage unit 47 is checked to allocate a currently available communication channel and a satellite modem (SCU).

The control channel S in FIG. 1 is also referred to as a service data network (SDN). The service data network SDN includes one outbound channel which is a transmission channel from the central control station 2 to the base station 3 and a maximum outbound channel which is a transmission channel from the base station 3 to the central control station 2 It consists of four inbound channels.

The outbound channel uses a time division multiplexing (TDM) scheme (TDM channel) and transmits synchronization and data packets. Each packet has a base station identification code for identifying a particular base station or has a wide area identification code for transmission to all base stations. The inbound channel uses multiple protocols by a random slotted aloha scheme (a slowed aloha channel) for communication of various base stations 3 with the central control station 2.

The Slotted Aloha channel consists of 14 packets, which are composed of 14 packets, which are used for functions related to call processing for call request, and 4 reservations (used for functions related to network operation and maintenance) Packet (Reserved Packet).

The base station 3 immediately outputs a control signal to the central control station 2 via a random packet of the slotted aloha channel whenever there is a call request from the subscriber so that the caller and the callee can communicate in real time.

Meanwhile, when the central control station manages a plurality of base stations, when a signal related to network operation and maintenance is transmitted from a base station to a plurality of base stations at the same time, signal collision occurs and data loss occurs So that the central control station can not broadcast an appropriate control signal to an arbitrary base station.

SUMMARY OF THE INVENTION Accordingly, the present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a slotted Aloha channel which is a transmission channel when a central control station receives data related to network operation and maintenance from a base station. It is an object of the present invention to provide a reservation packet allocating apparatus in a satellite communication system capable of preventing data loss by allocating a packet (a packet or a time slot) by reservation allocation (reservation packet).

1 is a general system configuration diagram for explaining an outline of a general satellite communication system;

Fig. 2 is a functional block diagram showing the configuration of the central control station 2 in Fig. 1. Fig.

3 is a functional block diagram showing the configuration of the network control unit 40 in Fig.

4 is a functional block diagram illustrating a configuration of a reservation channel allocation apparatus in a satellite communication system according to an embodiment of the present invention.

5 is an operation flow chart for explaining the operation of the apparatus having the configuration of FIG.

* A brief description of the main parts of the drawing

1: satellite 2: central control station

3A, 3B: base station 21: antenna

22: orthogonal mode converter 23: low noise amplifier

24: frequency down converter 25: intermediate frequency combination /

26: SCPC channel unit 27: frequency up converter

28: high power amplifier 40: network controller

41, 60: Processor 42: Service Channel Controller (SCC)

43: dual port RAM 44, 64: service data network manager (SDNM)

45: Program storage unit 46: Base station information storage unit

47: Channel information storage unit 50: Network management system

61: reservation packet information storage unit 62: frame number storage unit

63: offset number storage section

In order to achieve the above object, a reservation packet allocating apparatus in a satellite communication system according to the present invention includes an SDN manager for managing a service data network (SDN) composed of a TDM channel and an S-ALOHA channel between a central control station and a base station, A reservation packet information storage unit for indicating a reserved allocation state of reserved packets among ALOHA channels with a predetermined flag, a frame number storage unit for storing frame number data of reservation packets currently being transmitted from the base station, And an offset data storage unit for storing predetermined added numeric data and time slot number data. The SDN manager, in addition to a message requesting reservation allocation of reservation packets from an arbitrary device, The added number data is added to the frame number data of the number storage unit, And a reservation packet is reserved based on the data of the number of timeslots

FIG. 4 is a functional block diagram illustrating a configuration of a reservation packet allocating apparatus in a satellite communication system according to an embodiment of the present invention. Referring to FIG. 4, a reservation packet allocating apparatus configured as described above will be described in detail. In FIG. 4, the same reference numerals are assigned to the same parts as those in FIG. 3, and a detailed description thereof will be omitted.

Reference numeral 60 denotes a processor as a control unit for controlling the overall operation of the central control station 2 and reference numeral 61 denotes a transmission channel for transmitting predetermined data or response signals from the base station 3 to the central control station 2 Is a reserved packet information storage unit for indicating a use state of a reserved packet among the in-line switched aloha channels with a predetermined flag.

Herein, the processor 60 sets a corresponding time slot of the corresponding frame to '1' when an arbitrary packet is reserved, and reserves a reserved packet information storage unit 61 when reserving a reserved packet later And refer to it.

Reference numeral 62 denotes a frame number storage unit for storing the frame number of the reserved packet. The frame number storage unit 62 reads out the reserved packet storage unit 61 from the processor 60, And reference numeral 63 is an offset number storage for storing the offset value and the number of packets inputted from any device constituting the central control station 2. [

Here, each device constituting the central control station 2 performs a series of operations for smoothly driving the satellite communication system based on the control signal of the network control unit 40, and broadcasts necessary control data from the base station And receives and processes predetermined data. That is, each device of the central control station 2 outputs a predetermined control signal to the base station via the TDM channel in order to receive necessary data from the base station, and the base station 3 transmits the corresponding response signal to the slowed aloha channel Lt; / RTI >

In addition, reference numeral 64 denotes a service data network (SDN), which is a control channel, as described above with reference to FIG. 3, and also receives a reservation packet allocation request signal (offset number, packet number) (SDN) management processor for controlling to broadcast a frame number and a time slot number of a reservation packet.

Next, the operation of the apparatus having the above-described configuration will be described with reference to the operation flow chart of Fig.

First, when a message requesting packet transmission is input from an arbitrary device constituting the central control station 2 (ST1 step), the SDN manager 64, in addition to the packet transmission request message, inputs the frame number addition value and the packet number And stores the offset number data such as data in the offset number storage unit 63 (ST2).

Next, the SDN manager 64 reads the current frame number data from the frame number storage unit 62 (ST3).

Next, the SDN manager 64 calculates the new frame number by adding the above-described added numerical data input from the arbitrary apparatus to the current frame number data, and then calculates a new frame number in this frame based on the packet number data (ST4, ST5).

When there is an effective time slot, the base station 3 broadcasts the frame number and time slot number data including the time slot in step ST6.

Thereafter, the base station 3 performs communication with the central control station 2 through the frame number and time slot number data allocated to the above process.

On the other hand, if the valid time slot is insufficient for the time slot number data requested in step ST5, the time slot of the current frame is allocated, and then the offset number of the offset number storage unit 63 is incremented by '1' And performs the following operations to allocate time slots of the next frame (ST7).

As described above, according to the present invention, when a central control station receives data related to network operation and maintenance from a base station, a predetermined packet (a packet or a time slot) constituting a Slotted Aloha channel (Reservation packet), thereby preventing the loss of data. The reservation packet allocating apparatus in the satellite communication system can realize the reservation packet allocating apparatus.

Claims (2)

An SDN manager for managing a service data network (SDN) composed of a TDM channel and an S-ALOHA channel between the central control station and the base station, A reservation packet information storage unit for indicating reservation allocation status of reserved packets among the S-ALOHA channels with a predetermined flag, A frame number storage unit for storing frame number data of a reservation packet currently being transmitted from the base station, And an offset data storage unit for storing predetermined added numerical data and time slot number data input from an arbitrary apparatus, The SDN manager adds a summation numeric data to the frame number data of the frame number storage unit when the added numeric data is inputted together with a message requesting reservation allocation of a reservation packet from an arbitrary device to calculate frame number data, And allocates a reservation packet based on the received reservation information. The method according to claim 1, If the number of timeslots required in the calculated frame is insufficient, the SDN manager allocates an effective time slot in the current frame and then adds '1' to the added numeric data to calculate the frame number again, Wherein the reservation packet assigning unit allocates the reserved packet to the satellite communication system.