JP2001177463A - Satellite communication system utilizing un-stationary satellite - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify the processing required for routing revision of a communi cation packet on a satellite on the occurrence of path switching due to move ment of the satellite in a satellite communication system utilizing an un- stationary satellite. SOLUTION: A ground is divided virtually into a plurality of zones, a zone ID denoting a zone to which a communication destination belongs is included in a header of a communication packet delivered in the satellite communication system. As a processing on the occurrence of hand-off due to the movement of the satellite, a routing table in which a transmission channel and a destination satellite or the like are set in cross-reference with the zone ID is rewritten and communication packets by each satellite are routed by using this routing table.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a satellite communication system capable of providing a global communication service by using a plurality of orbiting satellites, and more particularly, to a mobile terminal or a mobile terminal via one or a plurality of satellites. The present invention relates to routing of communication packets in a satellite communication system that realizes communication between a satellite and an earth station.

[0002]

2. Description of the Related Art In conventional terrestrial cellular communication using the PDC, GSM, or the like, when a mobile terminal moves, a base station is switched (hand-off), and the mobile terminal can move while continuing communication. At this time, communication is performed without changing the communication path (path) to the switching node controlling the base station, and the relayed node does not change significantly. Therefore, once a communication partner is specified and a communication path is set, the relayed node rarely changes, and even when performing packet communication, routing to the same communication partner rarely changes.

Further, even in a satellite communication system using a geostationary satellite, since the geostationary satellite does not move relative to the ground station, the routing does not change when the geostationary satellite is viewed as an exchange node.

[0004] As a network using an orbiting satellite, a service of a satellite portable telephone according to the IRIDIUM, ICO system or the like is known. As a prior art for realizing a service of a satellite mobile phone, Japanese Patent Laid-Open Publication No.
There is a method of performing call processing using a logical channel as disclosed in Japanese Patent Publication No. 456/456.

[0005]

However, in the above-described method of allocating logical channels in the prior art, when performing packet communication, a plurality of channels must be allocated in order to simultaneously transmit a packet from one terminal to a plurality of destinations. The necessity is that when a satellite in the system moves and performs handoff, there is a problem that processing for a logical channel to which all terminals in the cell are related is required, and processing at the time of handoff becomes heavy.

In a network that can provide a global service by using a large number of low orbiting satellites (LEOs), a wireless communication is established between a mobile terminal and a satellite located above the mobile terminal and capable of communicating with the mobile terminal. A link is established, and communication is possible between the mobile terminal of the communication partner and a satellite that establishes a wireless link by connecting by satellite communication.

However, orbiting satellites are different from geostationary satellites in that the satellites move in orbit every moment, so that the satellite whose mobile terminal has established a radio link at the start of communication moves in orbit with the passage of time. Eventually, the service will be lower than the elevation angle that can be used and it will not be usable. In this case, the wireless link is re-established to another satellite located at a position higher than the elevation angle that can be serviced in the same orbit plane or another orbit plane satellite, and at the same time, the wireless link is established with the mobile terminal of the communication partner. It is also necessary to change the communication path with the satellite that has been set up.

[0008] Such processing occurs simultaneously for all mobile terminals belonging to the service area where switching has occurred because the satellite moves in the orbiting satellite. For this reason, the routing table used in the packet communication of each satellite is frequently updated, and a large number of control messages are generated accordingly.

The resources that can be loaded on each satellite at the time of launching the satellite are limited by weight and size restrictions, and since the satellite is located far from the ground, replenishment and repair of resources are extremely expensive. For this reason, it is desirable to use a simple system for controlling the network in order to improve the reliability of the satellite design.

An object of the present invention is to provide a satellite communication system capable of reducing a processing amount of a routing table switching process when a path switching occurs due to movement of a satellite in a communication network using a plurality of orbiting satellites. To provide.

[0011]

According to the present invention, there is provided an orbiting satellite comprising a plurality of orbiting satellites, a plurality of mobile terminals, and a plurality of earth stations having a function of connecting to a terrestrial network. In a satellite communication system that routes communication packets flowing in a network,
A function of performing inter-satellite communication with a plurality of orbiting satellites adjacent to each orbiting satellite and a function of communicating with a mobile terminal or an earth station are provided, and a communication packet to be routed includes information indicating an arrival destination of the communication packet. In this case, zone information for specifying an area to which the destination of the communication packet belongs in an area (zone) virtually dividing the surface on the earth is included.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a satellite communication system according to the present invention will be described.

In the satellite communication system of this embodiment, a satellite projects at least one beam onto the earth, and one satellite communicates with a plurality of zones. Also,
When the satellite is located at a position where service can be provided to the corresponding zone, the directivity of the corresponding beam is controlled to perform service using the same beam. This allows the satellite to provide communication services in accordance with the zone. If a satellite moves and cannot provide service to the zone, another satellite in the same orbit or a satellite in a different orbit will move, and the next satellite will provide service to the zone. Continue to do so.

Each satellite is provided with a routing table for routing a packet, and the next transfer is performed from the zone ID indicating the destination zone of the packet included in the packet using the routing table. A channel is determined, and packets are transferred to adjacent satellites using inter-satellite communication. This routing table is assumed to be periodically rewritten as the satellite moves with time.

In the satellite communication system of the present embodiment, the positions of all the satellites in the satellite communication system required for the calculation of the routing table are calculated from the orbital parameters of the satellites, or are predicted. Information about the position of the satellite is obtained from the ground station controlling the satellite. In this way, by calculating the positions of the satellites in real time or up to a certain time later at fixed time intervals, the satellite to be serviced for each zone is determined for each time. Further, based on the calculated coordinates of the satellites, a communication path to be used when a packet is transmitted from a certain satellite to another satellite at a certain time interval is determined, for example, a path arriving via the shortest path, and the determined communication path is determined. An inter-satellite link channel for transmitting a packet for a target zone from each satellite is determined based on the path.

As described above, in the satellite communication system of the present embodiment, the routing table for realizing the path determined at a certain time interval is distributed to each satellite, and the satellite is included in the packet by switching the routing table every time. The packet can be routed to the communication destination based on the zone ID to the target satellite.

Further, a position register for managing the position of a mobile terminal is provided in the communication satellite system of the present embodiment. The location register contains the zone ID to which the mobile terminal belongs.
When there is an inquiry about the position of the mobile terminal, the corresponding zone ID is answered. When there is a zone ID update request from the mobile terminal, the zone ID is updated.

Each satellite transmits a common channel, for example, a perch channel (BCCH), based on the satellite position information calculated as described above, using a beam corresponding to the zone. This BCCH contains a zone ID.

By receiving the BCCH, the terrestrial mobile terminal can know which zone it belongs to, and can know that the zone has moved or the communicable satellite has changed. When the mobile terminal can receive the BCCH due to power-on or the like, or when it detects that the zone to which the terminal belongs has changed, or at regular time intervals, the mobile station receives the zone ID from the position register. Register

When the mobile terminal detects that the zone ID has changed, the mobile terminal changes the zone ID to the communication partner.
D may be notified, and the communication partner may perform communication by adding a new zone ID thereafter.

At the start of communication or when transmitting a packet, the mobile terminal inquires of the position register about the zone ID where the communication partner exists, and transmits the packet with the zone ID added thereto.

The satellite linking the mobile terminal is used for transfer by inter-satellite communication based on the zone ID to which the communication partner belongs contained in the packet received from the mobile terminal and the routing table stored in the satellite. The packet to be transmitted is transmitted to the satellite to which the communication partner is linked while repeating this. A satellite that has a link with the mobile terminal of the communication partner detects that the packet is directed to a zone in which the satellite serves, and transfers the packet using the link with the communication partner.

Another embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a diagram showing a configuration example in one embodiment of a satellite communication system using the present invention. The satellite communication system according to the present embodiment includes a plurality of orbiting satellites (101), a plurality of earth stations (102), a plurality of mobile terminals (103), and a location register (HLR) (104). Reference numeral 105 denotes an example of a communication path between mobile terminals in the present embodiment. After the packet transmitted from the mobile terminal (103) is received by the satellite (101) serving the mobile terminal, the service is provided to the destination mobile terminal using inter-satellite communication. The data is transferred to the mobile terminal after being transferred to the transmitting satellite.

The satellite (101) is arranged in a low orbit (altitude 600 km to 2000 km) or a medium orbit (altitude 2000 km to 20000 km) above the earth. There are a plurality of satellite orbit planes, and at least one or more satellites are arranged in one orbit plane. The satellites are arranged in large numbers to provide a communication service covering a worldwide area.

The satellite (101) is connected to an earth station (10) on the ground.
2) Alternatively, wireless communication is performed with a terrestrial device such as a mobile terminal (103), and when the first satellite moves and the terrestrial device is out of the service range of the first satellite, the above-mentioned terrestrial device is over- A wireless link is established between the second satellite that has arrived at and the ground equipment, and communication is continued.

The satellite (101) has a function of performing not only communication with the ground equipment but also inter-satellite communication with a plurality of adjacent satellites, and communication packets received from the first mobile terminal use inter-satellite communication. By passing through a plurality of satellites, it is possible to communicate with a second terrestrial device that has a wireless link to a satellite different from the first satellite. The radio link between the satellite and the terminal is set so that multiple independent radio links can be established.
A multiple access scheme such as DMA, TDMA, CDMA, etc. is used.

The earth station (102) has a function of connecting to another network on the ground or another network using a satellite (gateway function), and can communicate with one or more satellites (101). It has a communication function between earth stations, a function to transfer a communication packet from a mobile terminal to another network such as a public telephone line or the Internet, or a function to transfer to a satellite (101). Earth station (10
2) In addition to the communication function, the configuration having a function as a government control station such as remote measurement, tracking, orbit / attitude control of the satellite may be adopted.

The location register (HLR) (104) manages the location of the mobile terminal in the satellite communication system and holds the subscriber information as a database.
It is composed of a computer system such as a workstation having a communication interface with an earth station or another network via a terrestrial network. In the example of FIG. 1, there is only one position register, but a plurality of position registers may exist in the satellite communication system.

The mobile terminal (103) has a function of communicating with other mobile terminals via the satellite (101) and terminals and servers of other networks via the earth station (102). When starting communication or transmitting a communication packet, the mobile terminal inquires the position register (104) of a zone ID indicating an area (zone) on the earth to which the terminal of the transmission destination belongs, and returns the zone ID obtained as a result. It has the function of transmitting packets to the satellite, including them in the packet. The zone and the zone ID will be described in detail below.

In addition, a zone ID indicating a communication partner zone is provided to the earth station (102) in place of the mobile terminal (103).
To the location register (104), or until the start of communication or the transmission of a communication packet until a notification from the earth station or satellite passing therethrough that there is no other party exists for a certain period of time. A configuration in which an ID is added and a packet is transmitted may be adopted.

FIG. 2 is a diagram showing a state of a zone virtually dividing the ground.

In the example shown in FIG. 2, the zones (202 to 20)
5) is within the service range of the satellite (201), one or more beams are allocated from the satellite, and communication with a plurality of mobile terminals in the zone and the satellite is possible. This virtual zone is fixed even if the satellite moves, and the satellite (201)
When the satellite is within the service range, the beam of the satellite is transmitted while controlling the shape of the beam according to the shape of the zone and the position of the satellite.

The shape of each zone may be non-uniform according to the communication traffic, and generally the area of the zone may be reduced in an area where there is a lot of communication traffic. The other zones in FIG. 2 are served by satellites other than satellite (201). Each zone has a unique ID for the zone
(Zone ID) is added, and is logically distinguished from other zones.

FIG. 3 is a diagram showing a state where the first satellite (301) moves on the zones (303 to 308) set as described above. 3A to 3C, the satellite (301) moves from right to left in the drawing.

In FIG. 3A, the zones (303 to 30)
6) is already within the service range of the satellite (301), the beam from the satellite is allocated, and the mobile terminal in the zone and the satellite (301) can communicate. From this state, the satellite moves from right to left in the figure and moves to zone (305).
FIG. 3B shows a state in which the vehicle has come near the sky.

In the state shown in FIG. 3B, the zones (307) and (308) are also moved with the satellite (30) as the satellite moves.
It shows a state in which the beam from the satellite is allocated within the service range of 1). In FIG. 3B as well, the satellite (301) operates the zones (303) to (306) by operating the shape and directivity of the beam mounted on the satellite based on the positional relationship between the position of the satellite and the zone. )
Irradiation according to the shape of.

Further, when the satellite (301) moves, as shown in FIG. 3C, the zones (303), (30)
4) becomes smaller than the service elevation angle of the satellite (301), and the service from the satellite (301) cannot be received. For the zones (303) and (304), the second satellite (30
As 2) enters the service range, these zones will continue to receive service through the newly moved satellite (302). In addition, the first satellite (30
The beam that has been providing service to the zones (304) and (305) in 1) provides a new service to the zone that has entered the range by the movement of the satellite (301).

FIG. 4 is a block diagram showing a configuration example of a communication system mounted on a satellite according to this embodiment.

The communication system of the present embodiment performs a link for a mobile terminal for performing communication with a mobile terminal, a link for an inter-satellite communication for performing an inter-satellite communication, a link for an earth station for performing a communication with an earth station, and routing of packets. Switching device (40
7) and a CPU for performing various controls of the communication system
(419) and a memory (418).

The mobile terminal link includes a plurality of mobile terminal communication devices (401) to (406). here,
(401) indicates a receiving antenna for receiving a radio signal from a mobile terminal, (402) is a receiving antenna beam forming circuit, and (403) is a decoder for converting a received radio signal into a digital signal. It is. Furthermore, (40
4) is a transmitting antenna for the mobile terminal, and (405)
Is a beam forming circuit for the transmitting antenna, and (406)
Is a modulator for transmission. The transmitting / receiving antennas (401) and (404) for the mobile terminal may be shared.

The beam forming circuits (402) and (405) are circuits for forming a beam from the antenna in accordance with the zone on the ground, and the CPU (419) controls the position of the satellite and the zone on the ground at regular intervals. The beam spread and direction are calculated from the positional relationship of the beamformer, and based on the result, a signal for controlling the beam is supplied to the beam forming circuits (402) and (40).
5) to generate a beam shaped according to the zone on the ground.

The earth station link is a communication device (408) to
(413). Here, (411) is a receiving antenna for receiving a radio signal from the earth station, and (412)
Denotes a beam forming circuit for reception and (413) a demodulator for converting a received radio signal into a digital signal. (40
8) indicates an antenna for transmission to the earth station, and (409)
Denotes a beam forming circuit for a transmission signal, and (410) denotes a modulator for transmission.

The CPU (419) calculates the direction of the beam from the positional relationship between the satellite and the earth station at regular time intervals, and outputs a signal for controlling the beam based on the calculation result to the beam forming circuit (412). 409) to generate a beam directed toward the earth station.

The inter-satellite communication links are provided with communication devices (414) to (417) for performing inter-satellite communication by the number of links with adjacent satellites for inter-satellite communication. here,
(414) is a transmitting antenna for performing inter-satellite communication, and (415) is a modulator. Also, (416) is a receiving antenna for inter-satellite communication, and (417) is a modulator.

As a communication method between satellites, besides a method using radio waves, communication between satellites using optical signals may be used. In inter-satellite communication using optical signals, an optical antenna is used instead of the antennas (414) and (416), and a light source such as a semiconductor laser and a mechanism for controlling the direction of light are used instead of the modulator (415). Instead of (417), an optical signal detector such as a photodiode, a tracking mechanism for a received optical signal, and the like are provided.

The switching device (407) determines a link to be transmitted based on the information of the header included in the packet received from the link for the mobile terminal, the link for the earth station, and the link for the inter-satellite communication, respectively. Sends a packet on the link.

The CPU (419) periodically calculates the positional relationship between the position of its own satellite and a terrestrial zone or earth station, and outputs a signal for forming a beam with each zone or earth station to a beam forming circuit (402). ), (405), (40)
9) and (412) to perform beam control, receive the distribution of a routing table for determining the transfer direction of the received packet from the position of the own satellite, or create or edit the switching device by itself, and configure the switching device (407). It has a control function such as a function of controlling and determining a transfer channel of a received packet.

The memory (418) stores a configuration of a terrestrial zone required to create a beam, a routing table, and the like.

Next, an example of a routing method used in the satellite communication system of the present embodiment will be described.

FIG. 5A shows an example of a routing table stored in the memory (418) mounted on the satellite (101). Here, reference numeral (501) in the figure indicates a zone ID to which a mobile terminal or an earth station to which a packet arrives, and (502) is an ID number of a channel to which a packet having the zone ID is to be transferred. Is shown. To the transmission channel ID (502), a channel number indicating the fact is added to the zone ID serving the own satellite.

Specifically, the zone ID is common to all the satellites, and when the zone ID of the destination in the packet provides service on its own satellite, the mobile terminal of the communication system shown in FIG. The channel number of the satellite link or the earth station link is shown. If the service is provided by another satellite, the channel number used by the inter-satellite communication link of the communication system shown in FIG. 4 is shown. I have.

FIGS. 5B and 5C show other examples of the configuration of the routing table. FIG. 5B shows the zone ID.
And a routing table showing the correspondence between the zone ID and the satellite that is providing service. Reference numeral (503) in the figure indicates a zone ID indicating the destination of the packet, and (504) indicates a zone. The number of the satellite providing the communication service to the ID (503) is shown.
FIG. 5C shows the satellite number and the channel number (transmission channel ID) to be used when transferring packets to this satellite. This transmission channel ID (50
6) includes information indicating to which satellite of the adjacent satellite the packet is to be transferred when the packet is transferred using the inter-satellite communication.

FIG. 6 shows an example of a packet format used in the satellite communication system of the present embodiment.

The format of the communication packet of this example is as follows.
Zone ID (601) to which the mobile terminal or earth station to which the packet arrives, ID (602) indicating the mobile terminal to which the packet arrives, ID (603) of the mobile terminal indicating the source of the packet, and packet transfer An ID (604) for distinguishing the connection being used and user data (605) are included.

FIG. 7 shows an example of a processing flow when the switching device (407) of the satellite (101) routes received packets.

When the packet received from the terminal link, the inter-satellite communication link, and the earth station link enters the switching device (407) (step 701), the destination zone ID (601) field included in the packet is set in the switching device (407). With reference to (Step 702), the routing table of FIG. 5 is searched (Step 703).

From the result of the search, the zone ID referred to
It is determined whether the satellite is being serviced by its own satellite or another satellite (step 704). If the zone ID is being served by another satellite, the routing table stored in the memory (418) is determined. Then, it is determined which channel should be used to transfer the packet (step 705), and the packet is transferred to the next satellite via the inter-satellite communication (step 706).

If the zone ID is being served by its own satellite, it is determined whether the packet is for a mobile terminal or an earth station based on the Destination Terminal ID in the packet (step 707). As a result, if the packet is for the mobile terminal, a channel for the mobile terminal is selected using the routing table of FIG. 5 (step 708), and the packet is transmitted from the transmission antenna (404) for the mobile terminal. (Step 709). If the packet is intended for an earth station, a transfer destination channel is selected from the channels intended for the earth station (step 710), and the packet is transmitted from the transmission antenna (408) intended for the earth station (step 711).

Next, a method for creating the routing table shown in FIG. 5 will be described.

In this embodiment, the terrestrial control station that controls the satellite system is a public control station that controls the satellite system, or a GPS (Global Positio) is assigned to each satellite.
By mounting a position determination system called ningSystem) and reporting from each satellite, the positions of all satellites in the system at the present time can be grasped. Predict the satellite position after a certain time based on the orbit parameters (orbital radius, elevating equatorial ascension, orbit inclination, orbital concentricity, perigee argument, average perigee declination) and the current satellite position data can do.

A satellite having an elevation angle higher than the service elevation angle in each zone is extracted from the predicted satellite position and position information of a predetermined zone, and the satellite having the highest elevation angle serves the zone in the zone. I decided to. FIG. 8 shows an example of a table showing the relationship between the time zone, the zone ID, and the satellite performing the service, which is obtained as a result.
01) indicates a zone ID, (802) indicates time,
(803) indicates the number of the satellite serving the zone at a certain time.

FIG. 9 shows, based on the predicted position data of all the satellites at a certain time, for example, the shortest path as the path from the first satellite to the second satellite, or the path arriving in the shortest time. FIG. 6 shows an example of a table indicating a transfer channel in each satellite when is selected. In FIG. 9, (901) indicates the source satellite number of the packet, (902) indicates the destination satellite number of the packet,
(903) indicates a channel number when transmitting a packet from a source satellite to a destination satellite, and this information includes information indicating to which satellite a packet is to be transmitted next in inter-satellite communication.

Here, the originating satellite (satellite A) and the destination satellite (satellite B) indicate the first and last satellites of the path, respectively, and the channel (90)
3) indicates the channel number for the next satellite to be relayed in the packet transfer from the originating satellite to the destination satellite. The next satellite (satellite C) that has been relayed is the channel number used for relaying from this satellite to the destination satellite, and the channel number to be used when satellite C is the originating satellite and satellite B is the destination satellite. Will be used.

From the table in FIG. 8, a satellite serving a certain zone at a certain time is determined, and which channel is used to transmit a packet to this satellite is determined from the table in FIG. This is divided for each satellite, which corresponds to the routing table stored in each satellite in FIG.

The process of creating the tables shown in FIGS. 8 and 9 and the routing table shown in FIG. 5 are performed, for example, by an earth station on the ground, and the created routing table is distributed to each satellite. Alternatively, by switching the routing table every time according to a timing signal of a clock held in the satellite, the routing table on the satellite can be updated in accordance with the movement of the satellite.

In distribution of the routing table of each satellite, control traffic can also be reduced by extracting and distributing only a portion of the routing table that is different from the previous state. Further, the above-described processing may be realized by independently processing each satellite.

Next, an example of processing when the mobile terminal performs location registration in the satellite communication system of the present embodiment will be described.

In the satellite communication system of the present embodiment, the satellite can estimate the current position from the ground control station or a clock mounted on the satellite and know the ID of the zone in which the service is performed. Taking advantage of this, the perch control channel (which is transmitted intermittently) from the satellite to the zone as in the example shown in FIG. 10 using, for example, a common channel commonly used among the terminals. The content of (BCCH) can include a zone ID.

FIG. 10 shows an example of the contents of the perch channel, where (1001) indicates the number of the satellite transmitting the perch channel, (1002) indicates the zone ID,
(1003) indicates the time during which the location registration is valid after the location registration, and (1003) indicates the transmission power of the perch channel from the satellite.

FIG. 11 shows an example of a procedure from when the mobile terminal turns on the power to when the mobile terminal performs location registration.

In this processing example, first, at step 110
When the power is turned on in step 1, the mobile terminal is set to an unregistered state in which position registration has not been performed in the initialization processing in step 1102. In step 1103, the mobile terminal is set to the zone where the mobile terminal is located from the satellite. BC being sent
Wait until the mobile terminal can receive the CH.

When the BCCH is received, step 110
4, the zone I included in the received BCCH
The information of D is compared with the information of the zone ID stored in the mobile terminal. Since the storage zone ID at power-on has been initialized, indicating that location registration has not been performed,
Make sure to register the location.

If the zone ID of the received BCCH is different from the zone ID stored in the mobile terminal, the location is registered in the location register (104) in step 1105. If the location registration fails for some reason (Yes in step 1106), step 1102
To initialize the location registration information in the mobile terminal and
Set the CH to a reception waiting state. If the location registration is successful, the timer is started for the time of the location registration timer included in the BCCH (step 1107), and the zone ID whose location has been registered is set in the storage zone ID (step 1108).

If it is determined in step 1104 that the zone ID included in the BCCH is the same as the stored zone ID, the mobile terminal does not move in the zone and does not need to perform location registration. However, in step 1109,
If it is determined that the location registration timer has timed out, the process proceeds to step 1105, and location registration is performed again.

In the location registration process of the mobile terminal, if the zone ID changes due to one of the mobile terminals moving during communication, a process of notifying the communication partner of the changed zone ID is added. Then, the notified communication partner may be configured to perform communication by adding the changed zone ID thereafter, or the communication partner may perform location registration with the changed zone ID and inquire the HLR. good.

[0077]

According to the present invention, by including the zone ID indicating the arrival area in the communication packet, the routing change processing in the satellite performed with the movement of the satellite uses the zone ID. Since this can be realized by changing the routing table, the processing amount can be reduced as compared with a case where the routing table for each mobile terminal is changed.

Therefore, according to the present invention, in a communication network using a plurality of orbiting satellites, it is possible to reduce the processing amount of switching processing of a routing table when path switching occurs due to movement of a satellite. It becomes possible to provide a system.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration example of a satellite communication system according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a configuration example of a terrestrial zone to which the present invention is applied.

FIG. 3 (A) is an explanatory diagram showing a situation where a ground zone is switched when a satellite moves. FIG. 3B is an explanatory diagram showing a state where a zone on the ground is switched when a satellite moves. FIG. 3C is an explanatory diagram showing a state where a zone on the ground is switched when a satellite moves.

FIG. 4 is a block diagram showing a configuration example of a communication device mounted on a satellite to which the present invention is applied.

FIG. 5A is a chart showing an example of a routing table mounted on a satellite. FIG. 5B is a chart showing another example of the routing table mounted on the satellite. FIG. 5C is a table showing another example of the routing table mounted on the satellite.

FIG. 6 is an explanatory diagram showing a format example of a packet to which the present invention is applied.

FIG. 7 is a flowchart illustrating an example of an algorithm when performing packet routing on a satellite.

FIG. 8 is a chart showing an example of a table indicating satellites serving a zone.

FIG. 9 is a chart showing an example of a table indicating channels used when transferring packets between satellites.

FIG. 10 is a chart showing an example of the contents of a perch channel.

FIG. 11 is a flowchart illustrating an example of an algorithm when the mobile terminal performs location registration from power-on.

[Explanation of symbols]

101 satellite 102 earth station 103 mobile terminal 104 location register (HLR) 105 communication path 201 communication satellite 202-205 zone 301 satellite 302-308 zone 401, 404, 408, 411, 414, 416 ... Antennas 402,045,409,412 ... Beam forming circuits 403,413,417 ... Demodulators 406,410,415 ... Modulators 407 ... Switching devices 418 ... Memory 419 ... CPU.

Claims (6)

[Claims] 1. A satellite communication system for routing a communication packet flowing in a network including a plurality of orbiting satellites, a plurality of mobile terminals, and a plurality of earth stations, wherein a header of the communication packet includes a header of the communication packet. As the information indicating the destination, zone information for specifying an area to which the destination of the communication packet belongs in a region (hereinafter, referred to as a zone) virtually dividing the surface on the earth is included, and the orbiting satellite A first link means for performing inter-satellite communication with another orbiting satellite, a second link means for performing communication with the mobile terminal or the earth station, and a routing for routing a communication packet using the zone information. Satellite communication system comprising: 2. The satellite communication system according to claim 1, wherein the orbiting satellite routing means, for each possible value of the zone information, transmits a communication packet to any orbiting satellite by using an inter-satellite communication channel. When storing the routing table that manages whether the packet can be delivered to the intended destination, and when transferring communication packets received by inter-satellite communication or transmitting communication packets from the own satellite, An inter-satellite communication channel selecting means for determining an inter-satellite communication channel to which a communication packet is to be transmitted by referring to the routing table. 3. The satellite communication system according to claim 1, further comprising: a position register storing a database for managing in which of said zones the mobile terminal is located, wherein One of the earth stations has a means for inquiring the location register of the zone information indicating the zone of the communication partner, and the zone information is transmitted after a predetermined time has elapsed or until it is externally notified that there is no other party. A satellite communication system characterized in that a packet transmission is performed by adding a packet. 4. The satellite communication system according to claim 2, wherein: a position calculation means for calculating and predicting the position of the orbiting satellite in the satellite communication system; Determining means for determining an orbiting satellite that can communicate with the zone, and a time signal obtained in the orbiting satellite or a time signal given from the outside, stored in the storage means of the orbiting satellite. Updating means for updating the routing table. 5. The satellite communication system according to claim 2, wherein: a table creating means for previously creating the routing table to be stored for each orbiting satellite; and a routing table obtained for each orbiting satellite. Further comprising a table distribution means for distributing to the orbiting satellite, wherein the orbiting satellite receives the distributed routing table, and converts the received routing table into a time signal obtained in the satellite itself or a time signal from outside. A satellite communication system further comprising table switching means for switching to a routing table stored at that time in response. 6. The satellite communication system according to claim 1, further comprising: a position register storing a database for managing in which zone the mobile terminal is located, wherein the orbiting satellite includes: Beam means for projecting a plurality of beams on the earth's surface, and common channel transmitting means for transmitting a common channel according to the shape of the zone corresponding to each of the plurality of beams simultaneously or in a time-division manner. The common channel transmitting means includes the zone information as information unique to a corresponding zone as the information on the common channel, and the mobile terminal receives the common channel from the orbiting satellite. A zone recognizing means for recognizing the zone information unique to a zone in which the mobile terminal is located; At the time of turning on the power, when the recognized zone information changes, and at least one of the constant time intervals, based on the recognized zone information, the information of the zone to which the mobile terminal belongs is based on the recognized zone information. A satellite communication system comprising: a position information registering unit that registers a position in a position register.