KR19980016548A - Reserved Packet Allocation Device in Satellite Communication System - Google Patents

Abstract

In the present invention, when a central control station wants to receive data related to network operation and maintenance from a base station, a predetermined packet (Packet or timeslot) constituting a slotted Aloha channel, which is a transmission channel, is reserved (reserved). The present invention relates to an apparatus for allocating reserved packets in a satellite communication system capable of preventing loss of data. The SDN manages a service data network (SDN) consisting 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 the reservation allocation status of the reservation packet in the S-ALOHA channel with a predetermined flag, a frame number storage unit for storing frame number data of the reservation packet currently transmitted from the base station, and any An offset data storage unit for storing predetermined addition value data and time slot number data inputted from an apparatus of The SDN manager calculates frame number data by adding the additional value data to the frame number data of the frame number storage unit when the addition value data is input together with a message requesting reservation allocation of the reservation packet from an arbitrary device. Next, the reservation packet is allocated based on the timeslot number data.

Description

Reserved Packet Allocation Device in Satellite Communication System

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication system using satellites. In particular, when a central control station wants to receive data related to network operation and maintenance from a base station, a predetermined packet constituting a slotted Aloha channel, which is a transmission channel ( The present invention relates to an apparatus for allocating reserved packets in a satellite communication system capable of preventing data loss by reserving a packet or timeslot).

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

In the above-mentioned satellite communication, a PAMA (Pre-Assignment Multiple Access) method for allocating communication channels for each subscriber according to the channel assignment method and a DAMA (Demand Assignment Multiple Access) method for allocating communication channels according to a subscriber's request There are two methods. 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 Figure 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, 3 (3A, 3B) is a data terminal and facsimile, such as an exchange, a telephone, a computer, etc. In addition to having an interface function for a terminal, the base station provides a call function between various terminals through data transmission and reception with the central control station 2.

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

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

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

In 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 21 through the antenna 21 using a polarization property of frequency. Orthogonal Mode Transducer (OMT) for separating and transmitting and receiving signals, 23 is a low-noise amplifier for low-noise amplifying 12.25 to 12.75 GkHz downlink frequency signal 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. An intermediate frequency combiner / distributor (IF C / D) for combining and outputting an intermediate frequency signal applied from the SCU: 26, and 26 is an intermediate applied from the intermediate frequency combiner / distributor 25. It is a SCPC channel unit that demodulates, decodes and outputs a frequency signal, and encodes, modulates, and outputs a message output from the network controller 40 to be described later.

Here, the intermediate frequency combination / distributor 25 is employed for system scalability when using a plurality of SCPC channel units.

Further, reference numeral 27 denotes a frequency up-converter for converting an IF signal of 70 MHz applied from the IF combination / distributor 25 into an microwave of 14.0 to 14.5 GHz to generate an uplink frequency signal. And 28 are high power amplifiers (HPAs) for amplifying uplink frequency signals output from the frequency up-converter 27.

Reference numeral 40 denotes a control message sent to each base station 3 through an arbitrary SCPC channel unit 261 to 26N, and then checks the state of each base station 3 based on a response message transmitted from the base station. In case that there is a call request from a specific base station, it is determined whether the other base station is in a possible communication state based on the information obtained in the polling process. It is a network control unit that performs system control, such as assigning a channel T and 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.

3 is a diagram schematically showing the configuration of the network control unit 40 described above. In the drawing, reference numeral 41 denotes a processor for controlling the entire system of the central control station 2, and 42 denotes the SCPC channel unit 26. In addition to extracting packet information from the message applied to the S-ALOHA (S-ALOHA) packet, the message of the time division multiplex (TDM) stream for the SCPC channel unit 26 is generated. Service Channel Controller (SCC) that generates and outputs

Further, 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 central control station 2 and a base station 3. SDN Manager that manages the service network (SDN), a communication channel.

Here, the SDN manager 44 is a processor that manages a common control channel (SDN) to centrally manage a plurality of users to share a satellite channel as a resource in a limited call.

Reference numeral 45 is a program storage unit for storing the operation program of the processor 41, 46 is a base station information storage unit for storing state information of each base station obtained by the polling operation of the network processor 41, 47 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, the TDM stream generates a message and outputs it to the SCPC channel unit 26.

Then, the SCPC channel unit 26 converts and outputs the message into an intermediate frequency signal of 70 MHz by encoding and modulating the message, and the intermediate frequency signal is combined for each frequency in the IF combination / distributor 25, The frequency increase converter 27 converts the uplink frequency signal of, for example, 14.5 GHz. The uplink frequency signal is output through the high power amplifier 28, the quadrature mode converter 22, and the antenna 21, and then transmitted to each base station 3 through the satellite 1 in FIG. .

On the other hand, the response message received by the antenna 21 from each base station 3 via the satellite 1, that is, the downlink frequency signal of 12.25 GkHz is frequency down through the orthogonal mode converter 22 and the low noise amplifier 23. It is applied to the converter 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. Will be.

In addition, the network controller 40 extracts packet information from the message to which the service channel controller 42 is applied, generates a slotted Aloha packet, and writes it to the dual port RAM 43. The packet data is read from the port RAM 43, and the base station information storage unit 46 is updated and registered based on this, thereby retaining state information for each base station.

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

In addition, when there is a call request from another base station to another base station during the above-described polling operation, the processor 41 first reads state information of the base station called from the base station information storage unit 46, If it is determined that the current communication is possible, and if it is determined that the communication is possible, the channel information storage unit 47 is examined to allocate the currently available communication channel and satellite modem (SCU).

The control channel S of FIG. 1 is also called a service data network (SDN). This service data network (SDN) is one outbound channel which is a transmission channel from the central control station 2 to the base station 3 and a maximum transmission channel which is the 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 a wide area identification code for transmission to all base stations. The inbound channel uses multiple protocols by a random slotted aloha scheme (slotted Aloha channel) for various base stations 3 to communicate with the central station 2.

The slotted Aloha channel consists of 18 packets, 14 random packets used for functions related to call processing for call calling, and 4 reservations used for functions related to network operation and maintenance. It is divided into a reserved packet.

The base station 3 operates so that the caller and the called party can communicate in real time by immediately outputting a control signal to the central control station 2 through a random packet of the slotted Aloha channel whenever there is a call request from the subscriber.

Meanwhile, the central control station manages a plurality of base stations. When the base station transmits signals related to network operation and maintenance, the signals are collided when the base stations transmit signals at the same time, resulting in loss of data. This prevents the central station from broadcasting appropriate control signals to any base station.

Accordingly, the present invention has been made in view of the above circumstances, and when a central control station wants to receive data related to network operation and maintenance from a base station, a predetermined channel constituting a slotted Aloha channel is used. It is an object of the present invention to provide an apparatus for allocating a reserved packet in a satellite communication system capable of preventing the loss of data by allocating a packet (a packet or timeslot).

1 is an overall system configuration for explaining the 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.

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

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

FIG. 5 is an operational flowchart for explaining the operation of the apparatus of FIG. 4. FIG.

* 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 / distribution unit

26: SCPC channel unit 27: frequency up converter

28: high power amplifier 40: network control unit

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

43: dual port RAM44, 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: reserved packet information storage unit 62: frame number storage unit

63: offset number storage unit

In the satellite communication system according to the present invention for realizing the above object, the reserved packet allocation apparatus includes an SDN manager for managing a service data network (SDN) consisting of a TDM channel and an S-ALOHA channel between a central control station and a base station, and A reservation packet information storage unit for indicating a reservation allocation status of a reservation packet in the ALOHA channel with a predetermined flag, a frame number storage unit for storing frame number data of a reservation packet currently transmitted from the base station, and input from an arbitrary device. And an offset data storage unit for storing predetermined addition data and time slot number data, wherein the SDN manager receives a frame requesting reservation allocation of a reservation packet from an arbitrary device together with the message. Frame number data by adding addition numerical data to frame number data of number storage unit Calculates the data, and then allocates the reservation packet based on the time slot number data.

4 is a functional block diagram showing the configuration of the reserved packet allocation apparatus in the satellite communication system according to the first embodiment of the present invention, which will be described in more detail with reference to FIG. In FIG. 4, the same reference numerals are assigned to parts performing the same functions as those of FIG. 3, and a detailed description thereof will be omitted.

In the figure, 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; A reserved packet information storage unit for indicating a state of use of a reserved packet in a predetermined Aloha channel with a predetermined flag.

In this case, when a predetermined packet is reserved, the processor 60 sets the corresponding time slot of the corresponding frame to '1', for example, to reserve the reserved packet later. It will be read and referenced.

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 the reserved packet storage unit 61 by the processor 60 to reserve the packet. The reference numeral 63 is an offset number storage unit for storing the offset value and the packet number input 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. The predetermined data is received and processed. That is, each device of the central control station 2 outputs a predetermined control signal to the base station through 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 slotted Aloha channel. Will be sent through.

In addition, reference numeral 64 manages the service data network (SDN), which is the control channel described above with reference to FIG. 3, and transmits to the corresponding base station based on the allocation request signal (offset number, number of packets) of the reservation packet inputted from each device. A service data network (SDN) management processor that controls to broadcast a frame number and a timeslot number of a reservation packet.

Next, the operation of the apparatus having the above-described configuration will be described with reference to the operation flowchart of FIG. 5.

First, when a message for requesting packet transmission is input from an arbitrary device constituting the central control station 2 (step ST1), the SDN manager 64 enters the frame number addition value and the number of packets, together with the packet transmission request message. Offset number data such as data is stored in the offset number storage section 63 (step ST2).

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

Subsequently, the SDN manager 64 calculates a new frame number by adding the addition value data inputted from an arbitrary device to the current frame number data, and then reserves time based on the packet count data in this frame. The slot is searched (steps ST4 and ST5).

Subsequently, if a valid timeslot exists, the frame number and timeslot number data including the timeslot are broadcasted to the base station 3 (step ST6).

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

On the other hand, if the valid time slot is insufficient for the time slot number data required 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 increased by '1' to step ST2. Then, the following operation is performed to allocate the time slot of the next frame (step ST7).

As described above, according to the present invention, when a central control station wants to receive data related to network operation and maintenance from a base station, a predetermined packet (Packet or timeslot) constituting a slotted Aloha channel, which is a transmission channel, is used. ), A reservation packet allocation device can be realized in a satellite communication system that can prevent data loss.

Claims (2)

An SDN manager for managing a service data network (SDN) consisting of a TDM channel and an S-ALOHA channel between a central station and a base station; Reserved packet information storage unit for indicating the reserved allocation status of the reserved packet in the S-ALOHA channel with a predetermined flag, A frame number storage unit for storing frame number data of a reservation packet currently transmitted from a base station; And an offset data storage unit for storing predetermined addition value data and time slot number data inputted from any device, The SDN manager calculates the frame number data by adding the additional value data to the frame number data of the frame number storage unit when the addition value data is input together with a message requesting reservation allocation of the reservation packet from an arbitrary device. An apparatus for allocating a reserved packet in a satellite communication system, comprising allocating a reserved packet based on data. The method of claim 1, When the number of timeslots required in the calculated frame is insufficient, the SDN manager allocates a valid timeslot in the current frame, adds '1' to the additive data, and calculates the frame number again to allocate the remaining timeslots. Reserved packet allocation device in a satellite communication system, characterized in that.