AU2006201548A1 - Satellite communication method, and satellite communication apparatus, earth station, and gateway station for use with the satellite communication method - Google Patents
Satellite communication method, and satellite communication apparatus, earth station, and gateway station for use with the satellite communication method Download PDFInfo
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Description
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AUSTRALIA
Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT Applicant: MITSUBISHI DENKI KABUSHIKI KAISHA Invention Title: SATELLITE COMMUNICATION METHOD, AND SATELLITE COMMUNICATION APPARATUS, EARTH STATION, AND GATEWAY STATION FOR USE WITH THE SATELLITE COMMUNICATION
METHOD
The following statement is a full description of this invention, including the best method of performing it known to me: SATELLITE COMMUNICATION METHOD, AND SATELLITE COMMUNICATION SAPPARATUS, EARTH STATION, AND GATEWAY STATION FOR USE WITH THE SATELLITE COMMUNICATION METHOD BACKGROUND OF THE INVENTION Field of the Invention 00 The present invention relates to a satellite communication method of carrying out satellite C communications between a gateway station and an earth
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station by way of a plurality of communications satellites CI that are flying approximately in the zenith direction one after another, and a satellite communication apparatus, an earth station and a gateway station for use with the satellite communication method.
Description of Related Art Systems for carrying out communications by using a group of Earth-orbiting communications satellites include Iridium communication system, Globalstar communication system, and so on. In Iridium system, there are provided 66 low-Earth-orbiting communications satellites each having an exchange function and an intersatellite communication function so that communications between terminals far away from each other can be established via communications among a plurality of adjacent communications satellites. In other words, each communication terminal on the ground can establish a communication link with a communications satellite with which it can communicate so that it can communicate with a faraway terminal that establishes a communication link with another communications satellite through communications between communications satellites.
Because communications satellites orbit around the Earth, a communications satellite that establishes a communication link with each communication terminal on the ground is not always identical, and therefore each H:\Valma\Keep\Specfications\P50880.0306 I -AUdoc 30/09/03 communication terminal goes away from the cover area of one communications satellite and then moves to the cover area of another communications satellite. In this case, each C- communication terminal on the ground disconnects a communication link with one communications satellite, and then establishes a communication link with another 00 communications satellite. This process is called a handover between communications satellites.
CI In order to perform a handover between communications
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satellites in a prior art satellite communication system, CI each communication terminal on the ground monitors an electric wave transmitted thereto from a communications satellite with which it establishes a communication link, and, when the received electric wave has a level below a predetermined value, transmits a handover request signal to the communications satellite. Disconnecting of the communication link with the communications satellite and establishment of another communication link with another communications satellite are then carried out in response to this request signal.
Fig. 13 is a sequence diagram showing a handover between communications satellites as disclosed in Japanese patent application publication (TOKKAI) No. 2000-315972, for example. Fig. 13 shows a handover from a first Earthorbiting communications satellite to a second Earthorbiting communications satellite, which is intended for a subscriber that is a communication terminal on the ground.
In Fig. 13, an NOC an earth station) transmits the physical location (latitude and longitude) of a point that is located just under each communications satellite, a schedule indicating the time when the physical location is measured, the physical location (latitude and longitude) of a point that is located just under an immediately preceding communications satellite, a schedule indicating the time H:\Valma\Keep\Specifaion \PO880.0306 IAU.doc 30/09/03
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when the physical location is measured, the physical Slocation (latitude and longitude) of a point that is located just under an immediately following communications C- satellite, a schedule indicating the time when the physical location is measured, and the physical location (latitude and longitude) of a point that is located just under an 00 adjacent communications satellite, a schedule indicating In the time when the physical location is measured to each of CI all communications satellites. Those pieces of information
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are registered in each communications satellite (Al, A2).
CI The first communications satellite determines a start time when a handover is started and an end time when the handover is completed based on the information about communications satellites, adds those pieces of time information to a control signal, and transmits the control signal to the second communications satellite that is the target of the handover. When the second communications satellite receives the control signal and the additional information, a handover between the first communications satellite and the second communications satellite is started (A3) In addition, a downlink message to the subscriber is transmitted from the first communications satellite to the second communications satellite The first communications satellite transmits the last communication data to the subscriber by way of a communication link that is established with the subscribe After that, the second communications satellite transmits the first communication data to the subscriber by way of a communication link that is newly established with the subscriber Then an upward communication link from the subscriber to the second communications satellite is prepared, and the last uplink (A7) to the first communications satellite and the first uplink (A8) to the second communications satellite are provided.
H :\Valmso\Xcp\Specifcations\P5880.0306 IAU.doc 30/09/03 A problem with a prior art satellite communication Ssystem is that because each communication terminal on the ground monitors an electric wave transmitted thereto from a C- communications satellite with which it establishes a communication link, and, when the received electric wave has a level below a predetermined value, transmits a 00 handover request signal to the communications satellite, a In communication link between the communication satellite and (1 another communications satellite is established in response
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to this request signal and a handover between the (1 communications satellites is carried out, and transmission of communication data to each communication terminal is performed, the implementation of the series of handover processes requires transmission of a large amount of data.
Another problem is that because the handover processing is carried out between two communications satellites, and each communications satellite needs a transmitter/receiver intended for establishing a communication link with another communications satellite, a computer intended for performing the handover processing and a storage unit intended for storing processing information, each communications satellite increases in size and decreases in reliability. A problem with a prior art method of performing a handover between communications satellites as disclosed in Japanese patent application publication (TOKKAI) No. 2000-315972 is that though each communication terminal on the ground can omit a procedure for making a request for the handover processing by predicting a start time when a handover is started based on positional information about the positions of communications satellites in question, those communications satellites have to repeatedly determine a start time when the handover processing is started and therefore have a large load of performing the handover processing.
H:\Valma\Kep\Speciicatona\P50880.0306 I AUdoc 30/09/03 6 SSUMMARY OF THE INVENTION According to one aspect of the present invention Ci there is provided a satellite communication method of carrying out communications between a gateway station and 00 an earth station by way of a plurality of communications I satellites that fly approximately in zenith direction one after another, said method comprising the steps of: IND when switching from communication via a first communication satellite to communication via a second communication satellite that flies next, at least one of said gateway station and said earth stations continuously transmitting switching instruction information by way of a transmission line passing through said first communication satellite; and another one of said gateway station and said earth stations receiving said switching instruction information, and switching to communication via said second communication satellite while receiving said continuous transmission.
According to another aspect of the invention there is provided a satellite communication apparatus comprising: a plurality of communications satellites that fly approximately in zenith direction one after another; and a gateway station and an earth station that communicate with each other by way of one of the plurality of communication satellites, wherein when switching from communication via a first communication satellites to communications via a second communication satellite that flies next, said gateway station continuously transmits switching instruction H:\Priyanka\Keep\epeci\2003248465 Amendments.doc 7/04/06 7 Qinformation and switches to communication via said second Scommunication satellite, and said earth station receives the switching instruction information and switches to communication via said second communication satellite while receiving said continuous 00 transmission n According to another aspect of the present invention there is provided a gateway station comprising: NO a transmitting unit for communicating with an earth station by way of a plurality of communication satellites that fly approximately in zenith direction one after another; a satellite switching instructing unit for instructing to switch from communication via a first communication satellite to communication via a second communication satellite that flies next; and a switching instruction packet generating unit for generating a packet including switching instruction information based on the instruction from said satellite switching instructing unit, wherein said transmitting unit continuously transmits said packet to said earth station for said earth station to be switched from communication via said first communication satellite to communication via said second communication satellite during the continuous transmission.
According to another aspect of the present invention there is provided A earth station comprising: a transmitting unit for communicating with a gateway station by way of a plurality of communication satellites that fly approximately in zenith direction one after another; a satellite switching instructing unit for H:\Priyanka\Keep\speci\2003248465 Amendments.doc 7/04/06 8 instructing to switch from communication via a first Scommunication satellites to communication via a second communication satellite that flies next; and a switching instruction packet generating unit for generating a packet including switching instruction 00 information based on the instruction from said satellite Sswitching instructing unit, wherein said transmitting unit continuously transmits said IND packet to said gateway station for said gateway station to be switched from communication via said first communication satellite to communication via said second communication satellite during tie continuous transmission.
According to another aspect of the present invention there is provided A satellite communication apparatus comprising: a plurality of communication satellites that fly approximately in zenith direction one after another; and a gateway station and an earth station that communicate with each other by way of one of the plurality of communication satellites, wherein when switching from a transmission line via a first communication satellite to a transmission line via a second communication satellite that flies next, said gateway station continuously transmits switching instruction information for switching to a transmission line via said second communication satellite, and said earth station switches from receiving communication from a transmission line via the first satellite to receiving communication from a transmission line via the second satellite during the continuous transmission and transmits switching instruction information for switching transmission by the earth H:\Priyanka\Keep\speci\2003248465 Amendments.doc 7/04/06 9 station from a transmission line via said first Scommunication satellite to a transmission line via said second communication satellite based on said switching CI instruction information received by the earth station.
According to another aspect of the present invention 00 there is provided An earth station comprising: In a transmitting unit and a receiving unit for CI communicating with a gateway station by way of a plurality
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of communication satellites that fly approximately in CI zenith direction one after another; a satellite switching instructing unit for instructing to switch from communications via a first communication satellite among said communication satellites to communication via a second communication satellite that flies next; and a switching instruction packet generating unit for generating a switching instruction packet including switching instruction information to switch transmission line based on the instruction from said satellite switching instructing unit, wherein said satellite switching instructing unit receives switching instruction information which is continuously transmitted from said gateway station and instructs switching of receive line while receiving said continuous transmission by the receiving unit, and instructs generating of said switching instruction packet to said switching instruction packet generating unit, and said transmitting unit continuously transmitting said generated switching instruction packet.
According to another aspect of the present invention there is provided A transmission method to transmit data packet to a receive station via communication satellites H:\Priyanka\Keep\speci\2003248465 Amendments.doc 7/04/06 10 that fly one after another, comprising the steps of: Stransmitting data packet to the receive station utilizing a first communication line via a first communication satellite; when switching from communication via said first 00 communication satellite to communication via a second n communication satellite, stopping the transmission of data O packet via said first communication line; IND continuously transmitting a switching instruction packet a plurality of times to instruct switching of communication line to the receive station, after the stopping if transmission of said data packet; and transmitting data packets which are not transmitted by the first communication line, by means of the second communication line via the second communication satellite, after said plurality of transmissions of the switching instruction packet have been completed.
According to another aspect of the present invention there is provided A receiving method to receive data packet from a transmitting station via communication satellites that fly one after another, comprising the steps of: receiving data packet from the transmitting station utilizing a first communication line via a first communication satellite; receiving a switching instruction packet to instruct switching of communication line a plurality of times from the transmitting station; starting switching from communication utilizing the first communication line via the first communication satellite to communication utilizing the second communication line via the second communication satellite, H;\Priyanka\Keep\speci\2003248465 Amendments.doc 7/04/06 \0 11
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O and completing the switching during receiving the Sswitching instruction packet a plurality of times; and receiving data packet which is not received by the first communication line, after said switching.
00 BRIEF DESCRIPTION OF THE DRAWINGS Fig. is a block diagram showing the structure of a Fig. 1 is a block diagram showing the structure of a
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0D 0q H:\Priyanka\Keep\speci\2003248465 Amendments.doc 7/04/06 satellite communication system that employs a satellite communication method in accordance with embodiment 1 of the present invention; C- Fig. 2 is a schematic diagram showing an example of a track that is formed on a ground by a communications satellite for use with the satellite communication method 00 in accordance with embodiment 1 of the present invention; Fig. 3 is a schematic diagram for explaining a CI handover that is carried out when switching between
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communications satellites is performed in accordance with Ci the satellite communication method in accordance with embodiment 1 of the present invention; Fig. 4 is a schematic diagram showing contents transmitted and received when a handover between communications satellites is carried out according to the satellite communication method of embodiment 1 of the present invention; Fig. 5 is a schematic diagram showing contents transmitted and received when a handover between communications satellites is carried out according to the satellite communication method of embodiment 1 of the present invention; Fig. 6 is a block diagram showing the structure of a gateway station for use with the satellite communication method in accordance with embodiment 1 of the present invention; Fig. 7 is a block diagram showing the structure of an earth station for use with the satellite communication method in accordance with embodiment 1 of the present invention; Fig. 8 is a schematic diagram showing contents transmitted and received when a handover between communications satellites is carried out according to a satellite communication method in accordance with H:\Valma\Keep\Spacfications\P880.03061AU.doc 30109/03 embodiment 2 of the present invention; SFig. 9 is a schematic diagram showing contents transmitted and received when a handover between C communications satellites is carried out according to a satellite communication method in accordance with embodiment 3 of the present invention; 00 Fig. 10 is a block diagram showing the structure of a switching instruction packet for use in the satellite Cl communication method in accordance with embodiment 3 of the
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0 10 present invention; C Fig. 11 is a schematic diagram showing contents transmitted and received when a handover between communications satellites is carried out according to the satellite communication method in accordance with embodiment 3 of the present invention; Fig. 12 is a schematic diagram showing time division frames included in a signal transmitted and received when a handover between communications satellites is carried out according to a satellite communication method in accordance with embodiment 4 of the present invention; and Fig. 13 is a sequence diagram showing a handover process performed by a prior art satellite communication system.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1.
A satellite communication method in accordance with embodiment 1 of the present invention, and a satellite communication apparatus, an earth station and a gateway station for use with the satellite communication method will be explained with reference to Figs. 1 to 7. Fig. 1 is a block diagram showing the structure of a satellite communication system that employs the satellite communication method in accordance with embodiment 1. In H:\ValmaKeep\Specifications 08800306 IAU.doc 30I09/03 Fig. 1, reference numerals la to Ic denote communications Ssatellites, respectively, reference numeral 2 denotes a communication area formed by the communications satellite C la, reference numerals 3a to 3c denote gateway stations, respectively, and reference numerals 4a to 4e denote earth stations, respectively. Each of the earth stations 4a to oo 4e can be a fixed station fixed to the ground, or a mobile In station installed in a vehicle, ship, aircraft, or the CI like.
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Each of the three communications satellites la to ic CI is a non-stationary communications satellite that can fly approximately in the zenith direction of a specific region, and forms multiple beams on the communication area 2a including this specific region. Fig. 1 shows a case where Japan is the specific region. The three communications satellites la to ic stay one after another in a range having a predetermined elevation angle within the specific region for eight hours in such a manner that the communications satellite la stays in the range having a predetermined elevation angle within the specific region for eight hours, the communications satellite Ib then enters the range having a predetermined elevation angle and stays in the range for eight hours after the communications satellite la goes away from the range having a predetermined elevation angle, and the communications satellite Ic then enters the range having a predetermined elevation angle and stays in the range for eight hours after the communications satellite Ib goes away from the range having a predetermined elevation angle, and provide communication services one after another. As a result, the group of three communications satellites can ensure communications between gateway stations and earth stations at all times. The above-mentioned range having a predetermined elevation angle can be an elevation angle H:\Valma\Xeep\Spcification\P50880.03061IAU.doc 30109103 range having elevation angles of 70 to 90 degrees (zenith), Sfor example, and is defined depending upon an individual communication satellite system. Furthermore, each of the C- plurality of communications satellites la to ic that are flying approximately in the zenith direction can be an elliptic orbit satellite having a periodicity of 24 hours, oo an orbit tilt angle of 45 degrees, an eccentricity of 0.139, an apogee altitude of 41,650 km, and a perigee CI altitude of 29,930 km, for example. Fig. 2 shows an
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example of a track which is formed on the ground by a point CI located directly under each communications satellite that is flying in such an orbit, and each communications satellite might be called a semi-zenith satellite.
Although the satellite communication system of this embodiment has the three communications satellites, the number of communications satellites included in an individual communication satellite system can be determined independently.
In Fig. i, each of the gateway stations 3a to 3c establishes a communication link with a client by way of a communication network, and communicates with each of the earth stations 4a to 4e by way of any one of the communications satellites la to ic. As a usage pattern of such a communication system, there are a case in which the client is a broadcaster, each of the plurality of earth stations 4a to 4e is a vehicle-mounted earth station an SNG station: Satellite News Gathering station), and data about video and voice from each vehicle-mounted earth station are transmitted through any one of the plurality of communications satellites la to Ic and are then transmitted to the broadcaster by way of a gateway station, and a case in which the client is a broadcaster, each of the plurality of earth stations 4a to 4e is a receiving antenna station that can be mounted on a general vehicle, and data about H:\Valma\Xeep\Speciftcaiona\PS0880.03061IAU.doc 30109/03 video and voice from the broadcaster are transmitted through any one of the plurality of gateway stations 3a to a 3c and are then transmitted to each earth station by way of C any one of the plurality of communications satellites la to Ic. Furthermore, there can be various usage patterns such as a pattern in which the client is a hospital and each of 00 the plurality of earth stations 4a to 4e is an emergency vehicle, and data about video and voice from each emergency vehicle that is an earth station are transmitted through
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any one of the plurality of communications satellites la to C- ic and are then transmitted to the hospital by way of a gateway station.
Fig. 3 is a schematic diagram for explaining a handover that is carried out when switching between communications satellites is performed for a transmission line from a gateway station 3 to an earth station 4. In Fig. 3, reference numerals 5a and 5b denote communication lines used for transmission of data packets from the gateway station 3 to the communications satellites la and ib, respectively, and reference numerals 6a and 6b denote communication lines used for transmission of data packets from the communications satellite la and Ib to the earth station 4, respectively.
The gateway station 3 modulates data packets with a carrier signal having a frequency of fl and transmits them to the communications satellite la by way of the communication line 5a within a time period during which the communications satellite la provides a communication service during which the communications satellite la is staying in a range having a predetermined elevation angle within the specific region). The communications satellite la receives the data packets from the gateway station 3 by way of the communication line 5a, modulates the received data packets with a carrier signal having a H:\Vama\Kcp\Speficatios\P&0880.03061 AU.doc 30/09/03 frequency of f2, and then transmits them to the earth station 4 by way of the communication line 6a. The earth station 4 thus receives the data packets by way of the C- communication line 6a. When the time period during which the communications satellite la provides a communication service ends and the next time period during which the oo communications satellite lb provides a communication In service comes, the gateway station 3 modulates data packets CI with a carrier signal having a frequency of fl and
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transmits them to the other communications satellite lb by CI way of the other communication line 5b within the next time period. The other communications satellite Ib receives the data packets from the gateway station 3 by way of the other communication line 5b, modulates the received data packets with a carrier signal having a frequency of f3, and then transmits them to the earth station 4 by way of the other communication line 6b. The earth station 4 thus receives the data packets by way of the other communication line 6b.
Next, handover processing that is carried out when switching from communications via the communications satellite la to communications via the other communications satellite lb will be explained with reference to Fig. 4.
Fig. 4 is a schematic diagram showing contents transmitted and received between communications satellites when a handover is carried out. In Fig. 4, reference numeral 7 denotes a data packet including data about video, voice, and so on. Data packets 7 are transmitted from the gateway station 3 to the earth station in order of P1, P2, P3, and Reference numeral 8 denotes a switching instruction packet for instructing the earth station 4 that is a receiver to perform switching between communication lines.
The gateway station 3 (referred to as GW station in the figure) transmits data packets P1, P2, and P3 to the communications satellite la by way of the communication H:\Valma\eep\Spsdfcios\PO880.0306 I-AU.doc 30/09/03 line 5a (having a frequency of fl), and the communications Ssatellite la then transmits them to the earth station 4 by way of the communication line 6a (having a frequency of C- f2). Based on a notification from a communications satellite management station, the gateway station 3 can grasp a time when the communications satellite lb enters 00 the range having a predetermined elevation angle and starts providing a communication service. As an alternative, the C-i gateway station 3 can determine the time when the
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communications satellite lb enters the range having a Ci predetermined elevation angle and starts providing a communication service based on information about the orbit of the communications satellite lb or can grasp the time based on an absolute time when the communications satellite lb comes flying and the periodicity of the communications satellite lb. When switching from the communication line via which communications are being carried out to the other communication line Sb (having a frequency of fl) to the communications satellite ib, the gateway station 3 continuously transmits a switching instruction packet 8 to the earth station 4. This switching instruction packet 8 is continuously transmitted to the communications satellite la by way of the communication line 5a, and is further transmitted from the communications satellite la to the earth station 4 by way of the communication line 6a. The earth station 4 thus receives a series of switching instruction packets 8 by way of the communication line 6a.
When receiving a switching instruction packet 8, the earth station 4 switches to the other communication line (switches to another receive frequency) based on information included in the packet, or switches to a certain communication line that is provided in advance shifts to another channel by one channel, for example). In other words, the earth station 4 switches H:\Valma\ep\Specifcatiwu3\P50880.03061-AU.doc 30109/03 from the communication line 6a to the other communication Sline 6b (having a frequency of f3) so as to receive data packets from the gateway station 3 by way of the other C-i communication line 6b.
A handover between communications satellites is carried out as previously mentioned. Fig. 4 further shows
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that the gateway station 3 continuously transmits a switching instruction packet 8 to the earth'station by way (1 of both the communication line 5a and the other
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communication line 5b so that a series of switching (1 instruction packets 8 is overlappedly transmitted to the earth station when performing switching between transmission lines. In this case, after switching to the other communication line 6b, the earth station 4 can further receive a series of switching instruction packets 8. When 'receiving a series of switching instruction packets 8 immediately after switching to the other communication line 6b, the earth station 4 can determine that there is no loss of data packets received thereby within a time period during which the earth station 4 performs the switching to the other communication line 6b.
Next, a description will be made as to a handover between communications satellites that is carried out when the earth station 4 is a transmitting side and the gateway station 3 is a receiving side in contrast to the case of Fig. 4. Fig. 5 is a schematic diagram showing contents transmitted and received between communications satellites when a handover is carried out in a case where the gateway station and earth station of Fig. 4 change places. Like the gateway station 3 of Fig. 4, based on a notification from a communications satellite management station, the earth station 4 of Fig. 5 can grasp a time when the communications satellite lb enters the range having a predetermined elevation angle and starts providing a H.\Valma\Keep\Specihcations\P60880.0306 IAU.doc 30109/03 communication service. As an alternative, the earth station 4 can determine the time when the communications satellite lb enters the range having a predetermined C- elevation angle and starts providing a communication service based on information about the orbit of the communications satellite lb or can grasp the time based on 00 an absolute time when the communications satellite lb comes flying and the periodicity of the communications satellite Ci lb. Transmission of data packets P1, P2, and P3 from the
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earth station 4, a series of switching instruction packets, C and data packets P4, P5 and so on, and reception of those packets by the gateway station 3 are carried- out in the same way as previously explained with reference to Fig. 4.
In view of bidirectional communications between the earth station 4 and the gateway station 3, as shown in Fig. 5, a communication line 9a (having a frequency of f4) is used between the earth station 4 and the communications satellite la, another communication line 9b (having a frequency of f4) is used between the earth station 4 and the other communications satellite Ib, a communication line (having a frequency of f5) is used between the communications satellite la and the gateway station 4, and another communication line 10b (having a frequency of f6) is used between the other communications satellite lb and the gateway station 4.
Next, the structure of the gateway station 3 will be explained. Fig. 6 is a block diagram showing the structure of the gateway station 3. In Fig. 6, reference numeral 11 denotes a transmitting antenna, reference numeral 12 denotes a receiving antenna, reference numeral 13 denotes a transmitting unit for transmitting packets to the earth station 4 by communicating with a communications satellite by way of the transmitting antenna 11, reference numeral 14 denotes a packet sending unit for sending data packets to H:\Valma\Keep\Speciications\POB8.03061AU.doc 30/09103 the transmitting unit 13, reference numeral 15 denotes a switching instruction packet generating unit for generating a switching instruction packet, reference numeral 16 c- denotes an interface for interfacing with a communication network, reference numeral 17 denotes a data packet generating unit for generating data packets from 0O communication data transmitted thereto by way of the communication network, reference numeral 18 denotes a data CI packet storage unit for temporarily storing data packets to
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be sent out by the packet sending unit, reference numeral C 19 denotes a receiving unit for receiving a signal transmitted thereto from the earth station 4 by way of a communications satellite when the earth station 4 transmits the signal thereto, reference numeral 20 denotes a received signal processing unit for converting the received signal from the earth station 4 into a transmission signal according to a protocol used by the communication network, and reference numeral 21 denotes a satellite switching instructing unit for instructing each of the transmitting unit 13 and the receiving unit 19 to switch between communications satellites between communication lines) Next, an operation of the gateway station 3 will be explained with reference to Fig. 6. Communication data from each client are input to the network I/F unit 16 by way of the communication network. The network I/F unit 16 sequentially delivers the received communication data to the data packet generating unit 17. The data packet generating unit 17 generates data packets from the received communication data and delivers them to the packet sending unit 14. When the format of packets transmitted via the communication network is the same as that of packets transmitted via the satellite communication system, the data packet generating unit 17 can make the received H:\Volma\eep\Specifcation\P 080.0306 I AU.doc 30/09/03 communication data to pass therethrough and output them just as they are. Furthermore, when the communication data received from the network I/F unit 16 are stream data or the like, the data packet generating unit 17 generates data packets by time-based compressing the communication data when necessary. The data packets generated by the data packet generating unit 17 and a switching instruction packet from the switching instruction packet generating unit 15 are input to the packet sending unit 14. While a switching instruction packet is input, the packet sending unit 14 delivers the packet to the transmitting unit 13 and delivers the data packets generated by the.data packet generating unit 17 to the data packet storage unit 18. In contrast, while no switching instruction packet is input, the packet sending unit 14 delivers the data packets generated by the data packet generating unit 17 to the transmitting unit 13. When data packets are stored in the data packet storage unit 18, the packet sending unit 14 gives a higher priority to the data packets and then delivers them to the transmitting unit 13. Though the transmitting unit 13 transmits the generated data packets to the earth station one by one, the transmitting unit 13 continuously transmits the switching instruction packet to the earth station several times. As previously explained with reference to Fig. 4, when performing switching from the communication line 5a to the other communication line the transmitting unit 16 continuously transmits a switching instruction packet to the earth station by way of both the communication line 5a, which has been selected before the switching, and the other communication line which is selected after the switching, so that a series of switching instruction packets are overlappedly transmitted to the earth station. The satellite switching instructing unit 21 determines whether to perform this switching H:\Valma\K p\Specifcations\PS0880.0306 I'AU.dc 30/03 I between the communication lines, then sends an instruction for switching between the communication lines to the transmitting unit 13, and instructs the switching C instruction packet generating unit 15 to generate and output a switching instruction packet. The satellite switching instructing unit 21 grasps a time when the next 0O communications satellite lb enters the range having a predetermined elevation angle and starts providing a C communication service based on a notification from a
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communications satellite management station. As an CI alternative, the earth station 4 determines the time when the communications satellite lb enters the range having a predetermined elevation angle and starts providing a communication service based on information about the orbit of the communications satellite Ib or grasps the time based on an absolute time when the communications satellite lb comes flying and the periodicity of the communications satellite lb. The satellite switching instructing unit 21 then provides a sequence of instructions for switching to the next communications satellite lb.
The receiving unit 19 of the gateway station 3 receives a transmission signal transmitted thereto from the earth station 4 by way of the receiving antenna 12. The receiving unit 19 then converts the received RF signal into a signal having a lower frequency and delivers it to the received signal processing unit 20. The received signal processing unit 20 extracts data packets or a series of switching instruction packets from the signal having a lower frequency while distinguishing them from each other.
The received signal processing unit 20 then delivers the data packets to the network I/F unit 16, and the series of switching instruction packets 13 to the satellite switching instructing unit 21. Furthermore, the received signal processing unit 20 time-based expands compressed stream H:\Valma\Kmep\Specificaion\P880.03061-AU.doe 30/09/03 O data or the like when necessary so as to reproduce stream data, and delivers them to the network I/F unit 16. The a network I/F unit 16 then transmits the data packets from C the received signal processing unit 20 to a client on the communication network. On the other hand, when receiving a switching instruction packet, the satellite switching 00 instructing unit 21 instructs the receiving unit 19 to perform switching between communications satellites C- between communication lines)
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Next, the structure of the earth station 4 will be C- explained. Fig. 7 is a block diagram showing the structure of the earth station 4. In Fig. 7, reference numeral 22 denotes an input and output I/F unit for inputting or outputting data about voice and video stored in the earth station 4, or control data. In Fig. 7, circuit components designated by the same reference numerals as shown in Fig.
6 are the same as or similar to those of Fig. 6.
The earth station 4 has a structure that is nearly the same as that of the gateway station 3. However, because the gateway station 3 transmits and receives communication data to and from a plurality of clients, and also transmits and receives these communication data to and from a plurality of earth stations 4, the gateway station 3 has a large amount of processed signals and increases in circuit size. In contrast, because data transmitted and received by the earth station 4 are limited to data about voice, video and so on handled by the earth station 4, the earth station 4 has a smaller circuit size than the gateway station 3. When the earth station 4 is a station that carries out only reception of data andso on, the earth station 4 can be comprised of the receiving antenna 12, the receiving unit 19, the received signal processing unit the satellite switching instructing unit 21, and the input and output I/F unit 22.
H:\Valma\Xeep\Spificaion\P5O880.0306 2AU.do 30109/03 As previously mentioned, in accordance with Sembodiment 1, a transmitting station transmits switching instruction information indicating an instruction for Ci switching between communication lines to a receiving station at predetermined time when a handover is carried out, and the receiving station performs switching between
OO
communication lines in response to the switching In instruction information from the transmitting station. As CI a result, the time required for performing the handover
\O
processing can be reduced, and the size of circuitry CI intended for performing the handover processing can be reduced.
Embodiment 2.
A satellite communication method in accordance with embodiment 2 of the present invention, and a satellite communication apparatus, an earth station and a gateway station for use with the method will be explained hereafter with reference to Fig. 8. Fig. 8 is a schematic diagram showing contents transmitted and received between communications satellites in accordance with embodiment 2 when a handover is carried out. In Fig. 8, circuit components designated by the same reference numerals as shown in Figs. 4 and 5 are the same as or similar to those of Figs. 4 and In Fig. 8, the gateway station 3 and the earth station 4 transmit and receive data packets and so on bidirectionally to and from each other, and communication lines are used when the gateway station 3 transmits data packets and so on to the earth station and when the earth station 4 receives data packets and so on from the gateway station and contents are transmitted and received by each of the gateway station 3 and the earth station 4, as previously explained with reference to Fig. 4. In Fig. 8, H:\Valma\Kecp\Specifcationa\P0880.0306lIAU.doc 30109/03 data packets 7 transmitted from the gateway station 3 are Sdesignated as Pal, Pa2, and When receiving a switching instruction packet 8, the earth station 4 determines that a C- handover occurs between two communications satellites based on this reception, and starts handover processing for transmission. First of all, the earth station 4 transmits 00 data packet Pbl and Pb2 to a communications satellite la by In way of a communication line 9a (having a frequency of f4).
CI The communications satellite la then transmits the data
\O
packets to the gateway station 3 by way of a communication line 10a (having a frequency of f5). In a case where the earth station 4 determines that a handover between communications satellites occurs, as previously mentioned, when switching from the communication line 9a via which communications are being carried out to another communication line 9b (having a frequency of f4) associated with another communications satellite lb, the earth station 4 continuously transmits a switching instruction packet 8 to the gateway station 3. This switching instruction packet 8 is continuously transmitted to the communications satellite la by way of the communication line 9a, and is further transmitted from the communications satellite la to the gateway station 3 by way of the communication line (having a frequency of f5). The gateway station 3 thus receives the switching instruction packet 8 by way of the communication line 10a. When receiving the switching instruction packet 8, the gateway station 3 switches between communication lines between receive frequencies) based on information included in the switching instruction packet 8, or switches to a certain communication line that is provided in advance shifts to another channel by one channel). In other words, the gateway station 3 switches from the communication line to the other communication line 10b (having a frequency H:\Valma\Keep\Secification\P50880.0306 1AU.doc 30/09/03 of f6) and then receives subsequent data packets by way of Sthe other communication line Fig. 8 shows a case where a series of switching C-i instruction packets are overlappedly transmitted by way of both the communication line 10a and the other communication line o10b when the earth station 4 performs switching oo between transmission lines. In this case, after switching to the other communication line o10b, the gateway station 3 can receive the series of switching instruction packets 8.
\O
When receiving a switching instruction packet 8 immediately CI after switching to the other communication line o10b, the gateway station 3 can determine that there is no loss of received data packets within a time period during which the gateway station 3 performs the switching to the other communication line.
On the other hand, when receiving a switching instruction packet, the earth station 4 determines that a handover occurs between communications satellites based on this reception, and then starts handover processing for transmission. A satellite switching instructing unit 21 as shown in Fig. 7 performs this handover processing. The gateway station 3 in accordance with embodiment 2 has the same structure as shown in Fig. 6, and the earth station 4 in accordance with embodiment 2 has the same structure as shown in Fig. 7.
As previously mentioned, in accordance with embodiment 2, in response to switching instruction information from the gateway station, the earth station performs switching between receive lines, and then transmits switching instruction information for instructing the gateway station to switch between receive lines to the gateway station. As a result, the earth station can omit a process of determining the time when a handover occurs between satellites, thereby reducing the time required for H:\Valma\Xeep\Sped&atioun\POB00.03O6 tAU1doc 30/09/03 performing the handover processing.
Embodiment 3.
A satellite communication method in accordance with embodiment 3 of the present invention, and a satellite communication apparatus, an earth station and a gateway 00 station for use with the method will be explained hereafter In with reference to Figs. 9 to 11. In accordance with CI embodiment 3, the satellite communication method includes
\O
the. step of continuously transmitting a switching C- instruction packet having a data section in which an already transmitted data packet is written and a header section in which switching instruction information is written so as to perform a handover between communications satellites. Fig. 9 is a schematic diagram showing contents transmitted and received between communications satellites in accordance with embodiment 3 when a handover is carried out. In Fig. 9, reference numeral 23 denotes a switching instruction packet having a data section in which an already transmitted data packet is written and a header section in which switching instruction information is written. In Fig. 9, circuit components designated by the same reference numerals as shown in Fig. 4 are the same as or similar to those of Fig. 4.
When switching from communications via a communications satellite la to communications via another communications satellite lb, handover processing is carried out as shown in Fig. 4, with the exception that a series of switching instruction packets 8 shown in Fig. 4 is replaced by a series of switching instruction packets 23 each having a header section in which switching instruction information is written, and the earth station 4 that is a receiver switches between communication lines in. response to a switching instruction packet 23. In addition, as shown in H:\Valma\Keep\SpecifcationsP588.03061AU.doc 30/09(03 Fig. 9, when switching between transmission lines, the Sgateway station 3 transmits a series of switching instruction packets 23 overlappedly to both a communication C- line 5a and another communication line 5b. In this case, after switching from a communication line 6a to another communication line 6b, the earth station 4 can receive a 00 series of switching instruction packets 23 from the gateway station 3. When receiving a series of switching (1 instruction packets 23 immediately after switching to the
\O
other communication line, the earth station 4 can determine (1 that there is no loss of received data packets within a time period during which the earth station switches to the other communication line. Even when the earth station 4 is a transmitting side and the gateway station 3 is a receiving side, a series of switching instruction packets 8 shown in Fig. 5 is replaced by a series of switching instruction packets 23 and handover processing is carried out between communications satellites as shown in Fig. Fig. 10 shows the structure of a switching instruction packet 23 in accordance with embodiment 3. A switching instruction packet 23 consists of a header section, in which a serial number N assigned to the packet and switching instruction information F are written, and a data section. The serial number N of a switching instruction packet 23 indicates the serial number of a previously transmitted data packet including data written in the data section of the switching instruction packet 23.
In the case of Fig. 10, because each switching instruction packet 23 stores data included in an immediately preceding data packet P3, the serial number of each switching instruction packet 23 is the same as that of the data packet P3. The switching instruction information F has a value that is either 0 indicating non-switching between communication lines or 1 indicating switching between H :\Valma\Keep\Specificationa\P5O88O0306 IAU.doc 30109/03 communication lines, for example. The serial number N is the same as that of a preceding packet that has already been transmitted. As a result, the receiving side can determine that each received switching instruction packet 23 is related to retransmission of an already transmitted data packet. In other words, the data section of each 00 received switching instruction packet 23 stores the In contents stored in the data section of a packet that has CI already been transmitted. The switching instruction
\O
information F is extracted from each received switching C instruction packet 23 by a received signal processing unit as shown in Figs. 6 and 7, and is then dqaivered to a satellite switching instructing unit 21. When the extracted switching instruction information F indicates an instruction for switching between communication lines F 1 in the above-mentioned example), the satellite switching instructing unit 21 performs a switching process of switching between communication lines. The received signal processing unit 20 then compares the serial number N of each received switching instruction packet 23 with that of each of packets which have already been transmitted thereto, and, when the serial number N is equal to that of a packet which has already been normally transmitted, discards data stored in the data section of each received switching instruction packet 23. In contrast, if the serial number N of each received switching instruction packet 23 is equal to that of a packet that has not been normally received, the received signal processing unit delivers data stored in the data section of each received switching instruction packet 23, as retransmitted data, to a network I/F unit 16 (see Fig. 6) when the received signal processing unit 20 is included in the gateway station 3, or to an input and output I/F unit 22 (see Fig. 7) when the received signal processing unit 20 is included in the earth H:\Vatma\Xeep\Specificatons\P50880.03061AU.doc 30/09/03 station 4.
SNext, another example of transmission and reception of packets will be explained with reference to Fig. 11. In C- Fig. 11, reference numeral 24 denotes a switching instruction packet having a data section in which an already transmitted data packet is written and a header 0O section in which switching instruction information is written. As illustrated in Fig. 11, while each switching CI instruction packet 23 includes the same data as an already
\O
transmitted data packet P3, each switching instruction CI packet 24 includes the same data as another already transmitted data packet P2. In Fig. 11, components or elements designated by the same reference numerals as shown in Fig. 4 are the same as or similar to those of Fig. 4.
It is clear from comparison between Fig. 9 and Fig.
11 that while in the case of Fig. 9 a switching instruction packet 23 is continuously transmitted from the gateway station 3 to the earth station 4, in the case of Fig. 11 a switching instruction packet 24 and a switching instruction packet 23 are mixedly transmitted from the gateway station 3 to the earth station 4. Thus, in the case of Fig. 11, because two switching instruction packets 24 and 23 respectively having data included in the two data packets P2 and P3, serial numbers, and a switching instruction are transmitted, not only data packet P3 but also data packet P2 can be retransmitted to the earth station. Each switching instruction packet 24 has the same structure (as shown in Fig. 10) as each switching instruction packet 23, and has a header section in which a serial number N and switching instruction information F are written, like each switching instruction packet 23.
As previously mentioned, in accordance with embodiment 3, each switching instruction packet has a data section in which already transmitted data are written. As H:\Valma\Keep\Specificaiiom\P50880.03061-AUdoc 00903 a result, retransmission of data can be carried out while a series of switching instruction packets for instructing switching between communication lines is transmitted.
Embodiment 4.
A satellite communication method in accordance with 00 embodiment 4 of the present invention, and a satellite In communication apparatus, an earth station and a gateway CI station for use with the method will be explained hereafter
\O
with reference to Fig. 12. The satellite communication CI method in accordance with embodiment 4 includes the step of handling and processing data and switching;7 instruction information in the form of time division frames in each of the gateway station 3 and the earth station 4. Fig. 12 is a schematic diagram showing time division frames included in a signal transmitted and received when a handover occurs between communications satellites in accordance with embodiments 4. In Fig. 12, reference numeral 25 denotes a frame including significant data, each frame of this type being shown by an open box, reference numeral 26 denotes a frame having switching instruction information, each frame of this type being shown by a hatched box, reference numeral 27 denotes a synchronization bit included in each frame, reference numeral 28 denotes a switching instruction bit included in each frame, and reference numeral 29 denotes data included in each frame. Fig. 12 shows both a case where the gateway station is a transmitting station and the earth station is a receiving station and a case where the earth station is a transmitting station and the gateway station is a receiving station. Communication lines being used are the same as those as shown in Figs. 3 and 4.
The transmitting station transmits frames 25 in each of which significant data are stored to the receiving H:\Valma\Xeep\Speciflcaion,\P50880.0306 IAU.dcc 30109/03 station by way of a communication line 5a first, and then Stransmits frames 26 when performing a handover between communications satellites. In response to a frame 26 transmitted thereto by way of the communication line 6a, the receiving station switches to another communication line 6b. After that, the receiving station receives 00 subsequent frames by way of the other communication line 6b. When switching the other communication line, the receiving station performs switching between receive
\O
frequencies and resynchronization among frames. The CI switching instruction bit included in each frame has a value that is either 0 indicating non-switching between communication lines or 1 indicating switching between communication lines, for example. Each frame 26 including switching instruction information has no significant data.
Embodiment A satellite communication method in accordance with embodiment 5 of the present invention has the step of recovering switching information, such as a switching instruction packet, switching instruction information or a switching instruction bit, which is transmitted from a transmitting station, when the switching information cannot be normally received for some reason, in the satellite communication method of either of embodiments 1 to 4.
A receiving station an earth station or gateway station) fails in the reception of the switching information in the following case: when shielding occurs within the range of a predetermined elevation angle in the zenith direction of the receiving station, the receiving station enters a tunnel.
Based on a notification from a communications satellite management station, the receiving station can grasp the time when a communications satellite that comes H:\Valma'Jeep\Specifiations\P50880.0306G1AU.doc 30(09/03 flying in the zenith direction for the next time enters the Srange having a predetermined elevation angle and starts providing a communication service. As an alternative, the C- receiving station can determine the time when the communications satellite enters the range having a predetermined elevation angle and starts providing a 0 communication service based on information about the orbit of the communications satellite or can grasp the time based C-I on an absolute time when the communications satellite comes
\O
flying and the periodicity of the communications satellite.
CI When receiving no switching information from the transmitting station even if the time thus gasped by the receiving station comes, the receiving station can forcedly switch between communication lines. As an alternative, when the receiving station cannot receive the switching information while it is transmitting and receiving bidirectionally to and from the transmitting station and the grasped handover time elapses, the receiving station transmits a request for retransmission of the switching information to the transmitting station and the transmitting station transmits the switching information again to the receiving station in response to the retransmission request. In Figs. 6 and 7, when a satellite switching instructing unit 21cannot receive the switching information from a received signal processing unit 20 after the handover time elapses, the satellite switching instructing unit 21 forcedly instructs a receiving unit 19 to perform switching between communication lines or instructs a transmitting unit 13 to make a request for retransmission of the switching information, so that the process of switching between communication lines is carried out.
As previously mentioned, when the earth station cannot receive any switching instruction information from H:\Valma\Kep\SpecificationAP588.030 IAU.doc 30NW03 35 Q)the gateway station, the earth station forcedly performs Sswitching between communication lines or makes a request of the gateway station for retransmission of switching instruction information. As a result, even if there is a loss of received switching instruction information due to 00 shielding or the like that occurs over the earth station, I a handover between communications satellites can be recovered.
IND Many widely different embodiments of the present invention may be constructed without departing from the spirit and scope of the present invention. It should be understood that the present invention is not limited to the specific embodiments described in the specification, except as defined in the appended claims.
In the claims which follow and in the preceding description, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.
It is to be understood that, if any prior art publication is referred to herein, such reference does not constitute an admission that the publication forms a part of the common general knowledge in the art, in Australia or any other country.
H:\Priyanka\Keep\speci\2003248465 Amendments.doc 7/04/06
Claims (16)
1. A satellite communication method of carrying out C' communications between a gateway station and an earth station by way of a plurality of communications satellites 00 that fly approximately in zenith direction one after Sanother, said method comprising the steps of: when switching from communication via a first O communication satellite to communication via a second communication satellite that flies next, at least one of said gateway station and said earth stations continuously transmitting switching instruction information by way of a transmission line passing through said first communication satellite; and another one of said gateway station and said earth stations receiving said switching instruction information, and switching to communication via said second communication satellite while receiving said continuous transmission.
2. The satellite communication method according to Claim 1, wherein said at least one of said gateway station and said earth stations also continuously transmits the switching instruction information by way of the transmission line via said second communication satellite, during said continuous transmission via said first communication satellite.
3. A satellite communication apparatus comprising: a plurality of communications satellites that fly approximately in zenith direction one after another; and a gateway station and an earth station that communicate with each other by way of one of the plurality H:\Priyanka\Keep\speci\2003248465 Amendments.doc 7/04/06 37 Q)of communication satellites, wherein when switching from communication via a first communication satellites to communications via a second communication satellite that flies next, said gateway station continuously transmits switching instruction 00 information and switches to communication via said second I communication satellite, and said earth station receives the switching instruction IND information and switches to communication via said second communication satellite while receiving said continuous transmission.
4. A gateway station comprising: a transmitting unit for communicating with an earth station by way of a plurality of communication satellites that fly approximately in zenith direction one after another; a satellite switching instructing unit for instructing to switch from communication via a first communication satellite to communication via a second communication satellite that flies next; and a switching instruction packet generating unit for generating a packet including switching instruction information based on the instruction from said satellite switching instructing unit, wherein said transmitting unit continuously transmits said packet to said earth station for said earth station to be switched from communication via said first communication satellite to communication via said second communication satellite during the continuous transmission.
A earth station comprising: a transmitting unit for communicating with a gateway H:\Priyanka\Keep\speci\200324465 Amendments.doc 7/04/06 38 station by way of a plurality of communication satellites Sthat fly approximately in zenith direction one after another; (1 a satellite switching instructing unit for instructing to switch from communication via a first 00 communication satellites to communication via a second I communication satellite that flies next; and a switching instruction packet generating unit for IND generating a packet including switching instruction information based on the instruction from said satellite switching instructing unit, wherein said transmitting unit continuously transmits said packet to said gateway station for said gateway station to be switched from communication via said first communication satellite to communication via said second communication satellite during the continuous transmission.
6. A satellite communication apparatus comprising: a plurality of communication satellites that fly approximately in zenith direction one after another; and a gateway station and an earth station that communicate with each other by way of one of the plurality of communication satellites, wherein when switching from a transmission line via a first communication satellite to a transmission line via a second communication satellite that flies next, said gateway station continuously transmits switching instruction information for switching to a transmission line via said second communication satellite, and said earth station switches from receiving communication from a transmission line via the first satellite to receiving communication from a transmission H \Priyanka\Keep\apeci\2003248465 Amendments.doc 7/04/06 39 line via the second satellite during the continuous transmission and transmits switching instruction information for switching transmission by the earth station from a transmission line via said first communication satellite to a transmission line via said 00 second communication satellite based on said switching n instruction information received by the earth station. ID
7. An earth station comprising: O 10 a transmitting unit and a receiving unit for communicating with a gateway station by way of a plurality of communication satellites that fly approximately in zenith direction one after another; a satellite switching instructing unit for instructing to switch from communications via a first communication satellite among said communication satellites to communication via a second communication satellite that flies next; and a switching instruction packet generating unit for generating a switching instruction packet including switching instruction information to switch transmission line based on the instruction from said satellite switching instructing unit, wherein said satellite switching instructing unit receives switching instruction information which is continuously transmitted from said gateway station and instructs switching of receive line while receiving said continuous transmission by the receiving unit, and instructs generating of said switching instruction packet to said switching instruction packet generating unit, and said transmitting unit continuously transmitting said generated switching instruction packet. H\Priyaka\Keep\speci\2003248465 Amendments.doc 7/04/06 40
8. The gateway station according to Claim 4, wherein said switching instruction packet generating unit stores data of data packet before the transmission of switching I instruction packet in a data section of generating switching instruction packet. 00 I
9. The earth station according to Claim 5, wherein said switching instruction packet generating unit stores O data of data packet before the transmission of switching instruction packet in a data section of generating switching instruction packet.
A transmission method to transmit data packet to a receive station via communication satellites that fly one after another, comprising the steps of: transmitting data packet to the receive station utilizing a first communication line via a first communication satellite; when switching from communication via said first communication satellite to communication via a second communication satellite, stopping the transmission of data packet via said first communication line; continuously transmitting a switching instruction packet a plurality of times to instruct switching of communication line to the receive station, after the stopping if transmission of said data packet; and transmitting data packets which are not transmitted by the first communication line, by means of the second communication line via the second communication satellite, after said plurality of transmissions of the switching instruction packet have been completed.
11. A receiving method to receive data packet from a transmitting station via communication satellites that fly H \Priyanka\Keep\speci\2003248465 Amendments.doc 7/04/06 41 F, one after another, comprising the steps of: receiving data packet from the transmitting station utilizing a first communication line via a first communication satellite; receiving a switching instruction packet to 00 instruct switching of communication line a plurality of times from the transmitting station; O starting switching from communication utilizing the IND first communication line via the first communication satellite to communication utilizing the second communication line via the second communication satellite, and completing the switching during receiving the switching instruction packet a plurality of times; and receiving data packet which is not received by the first communication line, after said switching.
12. Transmitting method according to claim wherein said switching instruction packet is transmitted by means of first communication line on which said transmission of data packet is stopped.
13. A method as claimed in any one of claims 1, 2, 11 or 12, and substantially as herein described with reference to the accompanying drawings.
14. A satellite communication apparatus as claimed in claims 3 or 6, and substantially as herein described with reference to the accompanying drawings.
15. A gateway station as claimed in any one of claims 4, 8 or 9, and substantially as herein described with reference to the accompanying drawings. H:\Priyanka\Keep\speci\2003248465 Anendents.doc 7/04/06 42
-16. An earth station as claimed in claim 5 or 7, and Ssubstantially as herein described with reference to the accompanying drawings. (N Dated this 5 th day of January 2006 00 MITSUBISHI DENKI KABUSHIKI KAISHA By their Patent Attorneys GRIFFITH HACK C Fellows Institute of Patent and Trade Mark Attorneys of Australia Trade Mark Attorneys of Australia HA\Priyanka\Keep\speci\2003248465 Amendments.doc 7/04/06
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AU2006201548A AU2006201548A1 (en) | 2000-05-12 | 2006-04-12 | Satellite communication method, and satellite communication apparatus, earth station, and gateway station for use with the satellite communication method |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AU48465/00A AU4846500A (en) | 1999-05-13 | 2000-05-12 | Methods for cleaning microelectronic substrates using ultradilute cleaning liquids |
| JP2002-286620 | 2002-09-30 | ||
| AU2006201548A AU2006201548A1 (en) | 2000-05-12 | 2006-04-12 | Satellite communication method, and satellite communication apparatus, earth station, and gateway station for use with the satellite communication method |
Related Parent Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| AU2003248465A Division AU2003248465A1 (en) | 2002-09-30 | 2003-09-30 | Satellite communication method, and satellite communication apparatus, earth station, and gateway station for use with the satellite communication method |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| AU2006201548A1 true AU2006201548A1 (en) | 2006-05-04 |
Family
ID=36406720
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| AU2006201548A Abandoned AU2006201548A1 (en) | 2000-05-12 | 2006-04-12 | Satellite communication method, and satellite communication apparatus, earth station, and gateway station for use with the satellite communication method |
Country Status (1)
| Country | Link |
|---|---|
| AU (1) | AU2006201548A1 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20170127323A1 (en) * | 2014-04-27 | 2017-05-04 | Novelsat Ltd. | Handover between satellites using a single modem |
| CN115854782A (en) * | 2022-12-05 | 2023-03-28 | 湖南航天有限责任公司 | Vehicle-mounted multi-connected-installation launching control device based on flying round and operation method |
-
2006
- 2006-04-12 AU AU2006201548A patent/AU2006201548A1/en not_active Abandoned
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20170127323A1 (en) * | 2014-04-27 | 2017-05-04 | Novelsat Ltd. | Handover between satellites using a single modem |
| EP3138323A4 (en) * | 2014-04-27 | 2018-01-17 | Novelsat Ltd. | Handover between satellites using a single modem |
| CN115854782A (en) * | 2022-12-05 | 2023-03-28 | 湖南航天有限责任公司 | Vehicle-mounted multi-connected-installation launching control device based on flying round and operation method |
| CN115854782B (en) * | 2022-12-05 | 2024-05-24 | 湖南航天有限责任公司 | Vehicle-mounted multi-joint loading launching control device based on fly-round projectile and operation method |
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