KR100292910B1 - Multimedia satellite communication system - Google Patents

Abstract

PURPOSE: A multimedia satellite communication system is provided to manage efficiently a multitude of user by allocating dynamically a limited internet address to a user. CONSTITUTION: A DNS(Domain Name System) server(11), an E-mail server(12), a WEB server(13), a proxy server, an MSP(Multimedia Service Provider), a router(16), and a DHCP(Dynamic Host Control Protocol) server(26) are connected with an IP switch(11). The router(16) is used for performing a connection process between a main center station(1) and an internet on the basis of an IP address. The router(16) converts IP packets to data of an ethernet frame or the data of the ethernet frame to the IP packets. A transmitting data processing portion(17) generates MPEG-2 TS packets by processing the data received from the IP switch(10). A modulation portion(18) modulates TS packet data of the transmitting data processing portion(17) to an intermediate frequency signal. An RF portion(19) is used for amplifying the intermediate frequency signal. A demodulation portion(20) is used for demodulating the intermediate frequency signal. A CDMA reception portion(21) is used for demodulating CDMA modulated data. A reception data processing portion(22) is used for converting the IP packet data or a control message to the data of the ethernet frame. A center station controller(23) is used for controlling all operations of the center station. A network management system(24) is used for managing totally a satellite network. A database(25) is used for storing various data.

Description

Multimedia satellite communication system

The present invention relates to a satellite communication system, and more particularly, to a multimedia satellite communication system capable of transmitting multimedia data such as image data to a satellite communication subscriber at high speed.

At present, wireless communication technology has been rapidly developed, and a wireless communication system that enables voice and data communication with a counterpart through a wireless network is becoming common. Accordingly, mobile communication systems and personal communication systems that allow communication subscribers to perform communication while moving are widely used. In addition, a method of connecting a general home communication device with an existing Public Switched Telephone Network (PSTN) network through a WLL (Wireless Local Loop) system or a satellite communication system is becoming more common.

In particular, in the case of a satellite communication system, there is an advantage of enabling ultra-long distance communication such as communication between countries without providing a separate communication line. Therefore, a satellite broadcasting system has been developed and distributed to directly receive satellite broadcasting in a general home through a set-top box by using the advantages of the satellite communication system. In addition, research to utilize mobile communication devices or personal communication devices using satellite communication is also rapidly being conducted.

Meanwhile, the Internet network, a global network based on a transport control protocol / Internet protocol (TCP / IP) communication method, has been established. Unlike the existing PSTN network, such an internet network is based on data packet transmission, so that a plurality of subscribers can use a single communication line in common, thereby significantly reducing communication costs and providing multimedia services. In addition to the construction of the Internet network, data communication using a personal computer has been activated.

However, in the conventional satellite communication system, since the network configuration is usually made of a unidirectional configuration and a closed loop, it is impossible for a general subscriber to access the Internet network using the satellite communication system. Therefore, in areas where communication networks are established based on satellite communication systems, such as mountain areas or island areas, subscribers can access the Internet or various multimedia services such as home banking or home shopping. It becomes impossible to use the light, which in turn is a great obstacle to the establishment and operation of the national network.

In general, when a communication subscriber uses the above-described Internet or multimedia service, the amount of data to be received is much higher than that of data transmitted to the service network, and since such received data is multimedia data, There is a problem that is very time consuming.

Therefore, combining a satellite communication system that does not require a separate communication line with the Internet, which is growing at a high speed, will provide many kinds of services to a large number of users. However, it should be noted that a communication method between a subscriber generating a small amount of service request data and an Internet service provider providing a large amount of multimedia service data should be considered to make the best use of expensive satellite resources.

On the other hand, when using internet service using satellite communication system, the following cases must be considered. In other words, the IP address system currently used on the Internet (for example, IP _V 4) has a shortage of IP addresses due to the rapid growth of subscribers using Internet services. Given that 12 C-class addresses are needed in succession, it is obvious that the current IP address system is not able to allocate the desired Internet address.

Accordingly, the present invention has been made in view of the above circumstances, and when a general subscriber requests a connection with a specific host on the Internet, the subscriber can efficiently accommodate a plurality of subscribers by dynamically allocating a limited Internet address to the subscriber. The purpose of the present invention is to provide a multimedia satellite communication system.

1 is a system schematic diagram for explaining an overview of a multimedia satellite communication system according to the present invention.

2 is a diagram showing the configuration of a transponder of a multimedia satellite communication system according to the present invention;

3 is a configuration diagram showing the configuration of the central station 1 in FIG.

FIG. 4 is a block diagram showing the configuration of the transmission data processing apparatus 17 in FIG.

FIG. 5 is a memory map showing a memory configuration of the subscriber information storage unit 174 of FIG.

6 is a data packet diagram showing the configuration of each data packet processed in the multimedia satellite communication system according to the present invention.

FIG. 7 is an operation flowchart for explaining the operation of the transmission data processing apparatus 17 shown in FIG.

FIG. 8 is a block diagram showing the configuration of a demodulator 20 and a CDMA receiver 21 in FIG.

9 is a block diagram showing the configuration of the set-top box 4 in FIG.

10 is an operation flowchart for explaining the overall operation of the multimedia satellite communication system according to the present invention.

* Brief description of the main parts of the drawing

1: central station 2, 3: antenna

4: set-top box 5: personal computer

6: satellite

Multimedia satellite communication system according to the present invention for achieving the above object is a multimedia satellite communication system having a set-top box physically coupled to the communication terminal, and a central station that is physically coupled to the Internet to perform the path control between the Internet and the set-top box In; The central station has a DHCP server that manages available IP addresses, and the DHCP server allocates an available IP address to the set-top box when a call connection is requested from the set-top box to the Internet, and the set-top box when a call is released. It is characterized in that for recovering the IP address assigned to.

According to the present invention having the above configuration, the subscribers can efficiently accommodate a large number of subscribers by allocating a limited Internet address when requesting connection to the Internet through a multimedia satellite communication system.

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

1 is a block diagram showing the overall system configuration of a multimedia satellite communication system according to the present invention.

In FIG. 1, reference numeral 1 denotes a central station connected to the Internet, which provides various multimedia services to terminal stations, and performs overall network operation management and control functions. Reference numeral 3 is a terminal station antenna, 4 is a set-top box as a terminal station providing multimedia services to a general subscriber, 5 is a personal computer as a terminal for a user to execute multimedia communication, and 6 is a satellite.

In general, a user using an Internet service often downloads (downloads) multimedia data through the Internet as described above. Therefore, the amount of data received from the Internet is higher than the amount of data transmitted to the Internet. So much. Therefore, in consideration of this, in the present system, in the case of a forward link transmitted from the central station 1 to the set top box 4, a large amount of messages can be transmitted through the TDM scheme, and from the set top box 4 In case of a return link transmitted to the central station 1, a code division multiple access (CDMA) scheme is used to accommodate a plurality of subscribers.

FIG. 2 shows the configuration of a transponder of the system, which has a frequency band f _A of 40 MHz for a forward link and a frequency band f _B of 40 MHz for a return link, for example. f _T ), for example, has a bandwidth of 80 MHz, and the return link is composed of a plurality of frequency channels f1 to fn with a bandwidth of approximately 1.5 MHz.

For example, 64 CDMA codes are allocated to each of the frequency channels f1 to fn. The central station 1 has a channel frequency for each set-top box 4 corresponding to the subscriber whenever the subscriber uses the Internet service. And a CDMA code are allocated to form a return link. In addition, when the central station 1 requests a connection from a specific subscriber to a specific host of the Internet, the central station 1 searches for a currently available IP address and transmits the IP address to the subscriber requesting access.

In addition, the central station 1 is coupled to the Internet based on TCP / IP, and transmits and receives various data with the Internet through an IP packet (Internet Protocol Packet). Then, for example, an MPEG-2 TS (Transport Stream) packet for a multimedia service is generated based on an IP packet for a subscriber received from the Internet, and the generated packet data is transmitted to the set-top box 4 through the TDM scheme. Done. Then, the CDMA modulated data received from the set-top box 4 is received and IP packets are generated based on the CDMA modulated data. The IP packets are looped based on the IP address transmitted from the subscriber and transmitted to the Internet.

In addition, the set top box 4 receives the TS packet transmitted from the central station 1 to provide multimedia data to the personal computer. Here, the reception of the TS packet is performed based on a PID (Packet Identifier), which is assigned by the central station 1 at the start of service. The set top box 4 transmits the IP packet data input from the personal computer 5 to the central station 1 together with the IP address allocated from the central station 1 by CDMA modulation and frequency modulation.

3 is a block diagram showing the configuration of the central station 1 described above.

In FIG. 3, reference numeral 10 denotes an IP switch for switching an IP packet. The IP switch 11 includes a Domain Name System (DNS) server 11, an E-mail server 12, and a Web (WEB) server 13 ), A proxy server, a multimedia service provider (MSP), a router (Router: 16), and a dynamic host control protocol (DHCP) server 26 may be combined. In this case, the MSP includes a home banking system, a home shopping system, a distance education system, a video conference system, and the like.

In particular, the router 16 executes a connection process between the central station 1 and the Internet based on an IP address, which converts an IP packet input from the Internet into the central station 1 as data of an Ethernet frame. The Ethernet frame transmitted from the central station 1 to the Internet is converted into an IP packet.

In the figure, reference numeral 17 denotes a transmission data processing apparatus for processing transmission data input from the IP switch 10 to generate, for example, an MPEG-2 TS packet, and 18 is output from the transmission data processing apparatus 17. A modulator for outputting an intermediate frequency signal of, for example, 70 MHz by quadrature phase shift keying (QPSK) modulation of TS packet data, and 19 converts an intermediate frequency signal output from the modulator 18 into a frequency up-conversion and high output amplification. And an RF device for outputting to the antenna 2 and converting a high frequency signal received through the antenna 2 into frequency down conversion and low noise.

In the drawing, reference numeral 20 denotes a demodulation device for demodulating an intermediate frequency signal input from the RF device 19, and 21 denotes CDMA demodulation of CDMA modulation data input by frequency demodulation in the demodulation device 20. A CDMA receiving device for outputting packet data, 22 is a receiving data processing device for processing data input from the CDMA receiving device 21, wherein the receiving data processing device 22 is an IP packet data from the set-top box (4) If the control message is received or converted to the data of the Ethernet frame is input to the IP switch 10. In addition, the reception data processing device 22 converts, for example, 100 baseT, that is, 100 Mbps data input from the CDMA reception device 21 into 10 baseT data and inputs the data to the IP switch 10.

In the drawing, reference numeral 23 denotes the control of the entire apparatus of the central station 1, the assignment of available IP addresses to the set-top box 4, PID, transmission channel frequency and transmission CDMA codes. A central international language processor, 24 is a network management system for the system operator to operate and manage the entire satellite network, 25 stores PID, frequency data and CDMA code data that can be assigned to the set-top box 4 In addition, a database in which billing information and the like for the subscriber are stored, 26 is a DHCP server that manages available IP addresses with an available address pool.

4 is a block diagram showing the configuration of the transmission data processing apparatus 17. In the drawing, reference numeral 171 generates and outputs an IP packet based on the Ethernet frame input from the IP switch 10 described above. In addition, the Ethernet interface converts the data of 100 baseT inputted into the data of 10 baseT and outputs the data, 172 is an input buffer for sequentially storing the IP packet data output through the Ethernet interface 171, 173 is the input buffer The type of input data is determined based on the header of the IP packet data stored in 172, and based on the determined result, the packets of the PS packet generation unit 175 and TS packet generation unit 176 to be described later. Control to generate and also control data applied from the Ethernet interface 171, for example, control input from the network management system 24 or the central international language processor 23 of FIG. An IP packet controller for controlling a transmission data processing unit 17 based on the data. Although not specifically shown in the figure, the IP packet controller 173 checks the state of each component of the transmission data processing apparatus 17 and displays the state information in the central international language processor 23 or the network management system 24. Will be sent out.

In the drawing, reference numeral 174 denotes a subscriber information storage unit for storing PIDs allocated for each set top box 4, which is a control PID corresponding to the IP address of each set top box 4 as shown in FIG. Map and store PID for traffic.

In the drawing, reference numeral 175 denotes a PS packet generation unit for generating a PS packet (Private Section Packet) based on data input from the IP packet controller 173, and 176 is input from the PS packet generation unit 175. MPEG-2 TS packet is generated based on PS packet data, PID (control PID, traffic PID, and information service PID) applied from the IP packet controller 173 and the traffic data stored in the input buffer 172. TS packet generation unit for outputting

Hereinafter, the operation of the transmission data processing apparatus 17 will be described based on the data packet structure shown in FIG. 6 and the flowchart shown in FIG.

First, when an Ethernet frame as shown in FIG. 6 (a) is input through the IP switch 10, the Ethernet interface 171 generates and outputs an IP packet as shown in FIG. 6 (b) based on the Ethernet frame. The IP packets are sequentially stored in the input buffer 172.

Meanwhile, when the IP packet is input and stored in the input buffer 172 (ST1), the IP packet controller 173 refers to the header of the stored packet data to determine whether the currently input packet data is control data for the set top box. Or whether it is traffic data for the personal computer 5 or service information for the set-top box 4 (ST2). At this time, when it is determined that the control data, the length data indicating the length of the data and the message data, that is, the data of the corresponding IP packet are read out from the input buffer 172 and input to the PS packet generation unit 175 (ST3). . In addition, the IP packet controller 173 reads the control PID corresponding to the IP address from the subscriber information storage unit 174 based on the IP address of the input data and outputs it to the TS packet generation unit 176 (ST4). ).

On the other hand, when the IP packet input in step ST2 is determined to be traffic data, the IP packet controller 173 transmits the length data of the corresponding traffic data stored in the input buffer 172 to the PS packet generation unit 175. In addition, based on the IP address of the IP packet (ST5), the traffic PID is read from the subscriber information storage unit 174 and sent to the TS packet generation unit 176 (ST6).

On the other hand, when it is determined that the IP packet input in step ST2 is service information for the information service, the IP packet controller 173 may compare the length data of the corresponding traffic data stored in the input buffer 172 and the data of the IP packet. In addition to sending to the PS packet generation unit 175 (ST7), the PID for information service included in the data field of the IP packet is read out and sent to the TS packet generation unit 176 (ST8).

Meanwhile, the PS packet generation unit 175 generates the PS packet data shown in FIG. 6C based on the length data and the message data applied from the IP packet controller 173 and outputs the PS packet data to the TS packet generation unit 176. In this case, the length data is included in the header portion of the PS packet, and the message data is allocated to the data field.

Then, the TS packet generation unit 176 applies the PS packet currently applied by the PS packet generation unit 175 based on the length data registered in the header of the PS packet data applied from the PS packet generation unit 175. It is determined whether this is control data (service information) or traffic data. That is, in general, in the case of traffic data, the data length thereof is larger than that of the control data. Therefore, when the length data value included in the PS packet data is greater than or equal to a predetermined value, the traffic data is smaller than the control data. It is determined.

Next, when the PS packet input unit 176 determines that the input PS packet is the control data, the TS packet generation unit 176 generates the TS packet as shown in FIG. 6 (d) based on the PS packet applied by the PS packet generation unit 175. On the other hand, if the input PS packet is determined to be traffic data, the TS packet of FIG. 6 (d) is generated based on the header data of the PS packet and the traffic data stored in the input buffer 172. .

In FIG. 6 (d), the TS packet is composed of a 4-byte TS header, a 184-byte payload allocated to a substantial data area, and a 16-byte RS (Reed Solomon) byte for error correction. In addition, the TS header includes an 8-bit sync byte having a predetermined fixed value, a 1-bit unit start indicator (US) for indicating the start criterion of the TS packet, and a 13-bit And a 4-bit continuity counter (CC) indicating a successive number of TS packets having the same PID. In this case, the PID is applied from the IP packet controller 173. If the currently transmitted TS packet is control data, the control PID, the traffic PID if the traffic data, and the information service PID are the information service, Will be allocated.

FIG. 8 is a block diagram showing the configuration of the demodulator 20 and the CDMA receiver 21 in FIG. 3. In FIG. 8, the demodulator 20 includes a plurality of demodulators 20 _{1 to} 20n. It is configured by. Here, each of the demodulators 20 _{1 to} 20n corresponds to the respective channel frequencies f1 to fn in FIG. 2, and demodulates the corresponding channel frequency signals to the CDMA receiver 21. Done.

In addition, CDMA reception apparatus 21 includes a plurality of CDMA receiver (21 ₁ ~21n), CDMA receiver (21 ₁ ~21n) of predetermined suhyo for each of the demodulator (20 ₁ ~20n), with adapted and provided with a Will be combined. Here, the CDMA receivers 21 _{1 to} 21 n correspond to the number of CDMA codes allocated to the respective channel frequencies f1 to fn in FIG. 2 and correspond to one channel frequency as described above, for example, 64. When CDMA codes are allocated, 64 CDMA receivers 21 _{1 to} 21n are coupled to the demodulators 20 _{1 to} 20n, respectively. Here, the CDMA receivers 21 _{1 to} 21 _{n are} distinguished as for the access channel 21A and the traffic channel 21B, where the number for the access channel and the traffic channel is variably set according to the characteristics of the system. .

9 is a block diagram showing the configuration of the set-top box 4 in FIG.

In the drawing, reference numeral 41 denotes a frequency down-conversion and low noise amplification of the high frequency signal transmitted from the central station 1, and a frequency up-conversion and high output amplification of the intermediate frequency signal output from the intermediate frequency generator 49 to be described later. 42 is a tuner for frequency-changing a high frequency signal output from the RF device 41, and 43 is an intermediate frequency signal output from the tuner 42, that is, a QPSK at the central station 1; A demodulator demodulates a modulated signal.

In the drawing, reference numeral 44 denotes a demultiplexer which extracts a TS packet corresponding to the set top box 4 from the TS packet data output from the demodulator 44, which is a register for storing PID information therein ( (Not shown) to store the PID applied from the processor 52 to be described later in the register. The TS packet including the PID stored in the register is extracted from the TS packets applied from the demodulator 43 and applied to the processor 52.

In the drawing, reference numeral 45 denotes a network interface card (NIC) that performs an interface with the personal computer 5, which converts Ethernet packets applied from the processor 52 into IP packets to convert the personal computer 5 into an IP packet. In addition to the above), the IP packet applied by the personal computer 5 is converted into an Ethernet packet and applied to the processor 52.

In the figure, reference numeral 46 denotes a serial transmission data frame based on the transmission data applied in parallel from the processor 52, and the transmission timing applied by the transmission timing generation unit 50 to be described later. A transmission frame generation unit sequentially outputs the transmission data frame in accordance with a signal. 47 is a CDMA modulation by mixing a CDMA code applied from the processor 52 with respect to transmission data output from the transmission frame generation unit 46. A CDMA channel transmitter for executing the data, 48 a modulator for modulating and outputting the data output from the CDMA channel transmitter 47, for example, QPSK, and 49 a modulator 48 based on the frequency data applied from the processor 52. Is an intermediate frequency generating unit for converting the modulated signal output from the predetermined frequency signal into a predetermined intermediate frequency signal.

In the drawing, reference numeral 50 denotes a transmission timing generator for generating a transmission timing signal for the transmission frame generator 46 under the control of the processor 52, and 51 denotes various data, in particular, assigned from the central station 1. It is a data memory in which an IP address, a control PID, a traffic PID, and an information service PID for receiving service information are stored.

In addition, reference numeral 52 denotes a processor for controlling the overall operation of the set-top box 4, which converts the TS packet for the personal computer 5 received from the demultiplexer 44 into an IP packet and converts it into an IP packet. In addition to the output box, data from the personal computer 5 input from the network interface card 45 is output to the transmission frame generation unit 46 and transmitted to the central station 1.

In addition, the processor 52 allocates a predetermined CDMA code to the CDMA transmitter 47 according to the control data transmitted from the central station 1 to the TS packet, and outputs frequency data to the intermediate frequency generator 49. As a result, CDMA modulation and frequency modulation on the data to be transmitted to the central station 1 are executed.

In addition, the processor 52 registers the control PID and the traffic PID allocated from the central station 1 to the demultiplexer 44 to receive and control the control data and traffic data transmitted from the central station 1.

Next, the overall operation of the multimedia satellite communication system having the above-described configuration will be described using the operation flowchart shown in FIG. In addition, in the multimedia satellite system according to the present invention, it is possible for a subscriber to connect to various servers including MSP such as home shopping, home banking, and the Internet using the system. An example of connecting to the Internet will be described.

First, the network management system 24 of the central station 1 has various information required when the set-top box 4 requests access to the central station 1, for example, a CDMA code for transmitting a control message to the central station 1. And an information service providing channel frequency data (step A1).

That is, the network management system 24 generates an Ethernet frame including the CDMA code, channel frequency data, and PID for information service for common reception in all set-top boxes 4, and transmits data through the IP switch 10. It is transmitted to the processing device 17.

Subsequently, in the transmission data processing apparatus 17 shown in FIG. 4, when the IP packet sent out from the network management system 24 is stored in the input buffer 172, the IP packet controller 173 refers to the header. The type of the IP packet is determined. At this time, if the IP packet is control data for the set-top box 4 and is determined to be an information service, the IP packet controller 173 reads PID information included in the data field of the corresponding IP packet to generate a TS packet. In addition to the output to the unit 176, the length data and the message data of the IP packet data is output to the PS packet generation unit 175.

Accordingly, the control data transmitted from the network management system 24 is converted into a PS packet through the PS packet generation unit 175, and is further converted into a TS packet through the TS packet generation unit 176. The TS packet is transmitted to the set top box 4 through the modulator 18 and the RF device 19.

In addition, the information service described above is repeatedly executed at regular intervals, for example, when the number of TS packets transmitted from the central station 1 to the set top box 4 reaches 100.

On the other hand, in the set top box 4, the processor 52 first reads the information service PID from the data memory 51 and registers it in the demultiplexer 44. When the service information transmitted from the central station 1 is received by the demultiplexer 44 and input to the processor 52, the processor 52 receives access data received through the information service, that is, the central station 1. CDMA code data and channel frequency data used when requesting a call connection are stored in the data memory 51 (step B1).

When the access request for the Internet, that is, the call connection request, is input from the personal computer 5 in the above state (step B2), the processor 52 inputs the subscriber information input through the network interface card 45, that is, the subscriber ID. After generating a predetermined control message based on a password, a subscriber address, and the like, the control message is transmitted to the transmission frame generation unit 46 and access information stored in the data memory 51, that is, the central station. The CDMA code data and channel frequency data transmitted from (1) are allocated to the CDMA channel transmitter 47 and the intermediate frequency generator 49 to execute the access request for the central station 1 (step B3).

On the other hand, in the central station 1, the control message sent from the set-top box 4 is input to the demodulation device 20 through the RF device 19, and the access control message is for access in FIG. It is input to the received data processing apparatus 22 through the assigned demodulator 20 and the CDMA receiver 21A. Then, the reception data processing apparatus 22 generates an Ethernet frame based on the control message and applies it to the central international language processor 23 through the IP switch 10 in FIG. 3.

Then, when the access request is input through the above-described process (step A2), the central international language processor 23 first compares the subscriber information included in the control message with the subscriber information stored in the database 25. It is determined whether the subscriber who has been the access request is a legitimate subscriber (step A3).

At this time, if it is determined that the user is a legitimate subscriber, the central international language processor 23 accesses the DHCP server 26 and the database 25. The IP address, the control PID, and the traffic PID for the set-top box 4 are accessed. The channel frequency and the CDMA code are assigned. That is, the central international language processor 23 generates the above-described IP address, PID information, channel frequency data, and Ethernet frame for transmitting the CDMA code, and transmits them to the transmission data processing apparatus 17 through the IP switch 10. The transmission data processing device 17 generates a TS packet based on the Ethernet frame and transmits the TS packet through the modulation device 18 and the RF device 19 (step A4). At this time, the information service PID is used as the PID of the TS packet transmitted to the set top box 4.

Thereafter, the network management system 24 transmits control data to the IP packet controller 173 of the transmission data processing apparatus 17 through the IP switch 10, thereby allocating the current access information to the subscriber information storage unit 173. In response to the IP address, the control PID and the traffic PID are registered.

On the other hand, in the set top box 4, when the control data is input through the demultiplexer 44, the processor 52 first determines whether it has made an access request. In addition, the processor 52 of the set-top box 4, which has made an access request, sets the control PID and the traffic PID assigned from the central station 1 to the demultiplexer 44, and is allocated from the central station 1. The CDMA code and the channel frequency data are transmitted to the CDMA channel transmitter 47 and the intermediate frequency generator 49. Then, the personal computer 5 is notified of the successful call connection through the network interface card 45.

Subsequently, when an IP packet for transmitting to the Internet from the personal computer 5 is input, the network interface card 45 converts it into an Ethernet packet and inputs it to the processor 52, and the processor 52 converts it into an IP packet. By converting and outputting to the transmission frame generation unit 46, the corresponding traffic data is transmitted to the central station 1.

In the central station 1, when traffic data is received from the set top box 4, it is input to the demodulation device 20 through the RF device 19, and in FIG. The demodulator 20 and the CDMA receiver 21B corresponding to the channel frequency and the CDMA code allocated to the input data are inputted to the reception data processing apparatus 22. Then, the reception data processing device 22 converts the input IP packet into an Ethernet frame and applies it to the router 16 through the IP switch 10, and the router 16 converts the input Ethernet frame into an IP packet. To the Internet.

On the other hand, when the IP packet for the subscriber to the call connection is input to the router 16, the router 16 converts the input IP packet into an Ethernet frame to the transmission data processing device 17 through the IP switch 10 Will be entered. In FIG. 4, the input Ethernet frame is converted into an IP packet through the Ethernet interface 171 and sequentially stored in the input buffer 171.

Subsequently, the IP packet controller 173 recognizes that the inputted IP packet is traffic data for the subscriber by determining the header of the IP packet stored in the input buffer 171, and then corresponds to the corresponding IP address. The traffic PID is read from the subscriber information storage 174 and applied to the TS packet generator 176.

Accordingly. Traffic data for a particular subscriber received from the Internet is converted into a TS packet assigned a PID for the subscriber and transmitted to the set top box 4.

In the set-top box 4, when the above-described TS packet is input through the demultiplexer 44, the processor 52 determines the received data based on the PID included in the header of the input TS packet. If it is determined that the TS packet is traffic data, an Ethernet frame is generated based on the TS packet and input to the network interface card 45. In addition, the network interface card 45 converts the Ethernet frame input from the processor 52 into an IP packet and transmits it to the personal computer 5.

Therefore, through the above-described process, the subscriber can execute the network connection with the Internet through the personal PC.

On the other hand, when a call release, i.e., an access release request is input from the personal computer 5 (step B5), the processor 52 generates a control message for the call release request based on this, and outputs it to the transmission frame generation unit 46. Being. This call request message is transmitted to the central international language processor 52 of the central station 1 through the above-described method (step B6). Then, the central international language processor 23 recovers the IP address, control PID, and traffic PID assigned to the set-top box 4 based on the input control message. That is, the central international language processor 23 first sends control data to the set-top box 4 to notify that call release has been made, sets the corresponding PID of the database 25 to a non-use state, and DHCP. The server 26 is accessed to set the assigned IP address to an unused state. In addition, the billing information for the call usage up to now is stored in the database 25, and the control data is transmitted to the transmission data processing unit 17 to store the corresponding IP address stored in the subscriber information storage unit 174. The corresponding control PID and traffic PID are deleted (step A5).

Further, in the set top box 4, when control data indicating call release is received from the central station 1, the processor 52 resets the control PID and the traffic PID set for the demultiplexer 44, and the information service. The call processing for the subscriber is terminated by setting the PID for the service and resetting the CDMA channel transmitter 47 and the intermediate frequency generator 49. FIG.

Therefore, in the above embodiment, the subscribers can efficiently accommodate a large number of subscribers by allocating a limited Internet address when requesting connection to the Internet through the multimedia satellite communication system.

In addition, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the technical scope of the present invention.

As described above, according to the present invention, when a general subscriber requests a connection with a specific host on the Internet, the multimedia satellite communication can efficiently accommodate a plurality of subscribers by dynamically allocating a limited Internet address to the subscriber. The system can be realized.

Claims (1)

In a multimedia satellite communication system having a set-top box physically coupled to a communication terminal, and a central station physically coupled to the Internet to perform path control between the Internet and the set-top box, the central station has a pool of available IP addresses. DHCP server that manages possible IP addresses, PID, frequency data and CDMA code data that can be assigned to the set-top box, a database storing billing data for subscribers, the DHCP server when requesting a call connection to the Internet from the set-top box, and Access the database to allocate available IP address and control PID, traffic PID, channel frequency and CDMA code to the set-top box to which the subscriber is connected, and assign IP address and control PID and PID for traffic when call release is requested. Configured to include a processor that controls the system as a whole Multimedia satellite communication system, characterized in that.

Images