User satellite, relay satellite, satellite system and communication method

A relay satellite, comprising:

• a communicator that communicates with an earth station;
• an optical signal transceiver that, in response to a communication request for a satellite received from the earth station, transmits an optical beacon to the satellite and receives a response signal from the satellite detecting the optical beacon;
• an optical communicator that establishes inter-satellite optical communication with the satellite based on reception of the response signal;
• and
• a communication controller that uses the communicator to relay data received from the satellite in the inter-satellite optical communication to the earth station,
• wherein the optical communicator performs inter-satellite optical communication based on a predetermined communication schedule and upon receiving a communication request for a satellite from the earth station, uses spare time in the communication schedule to establish inter-satellite optical communication with the satellite.

A data relay method implemented by a relay satellite, the method comprising:

• transmitting, in response to a communication request for a satellite received from an earth station, an optical beacon to the satellite;
• receiving a response signal from the satellite detecting the optical beacon;
• establishing inter-satellite optical communication with the satellite based on reception of the response signal;
• and
• relaying data received from the satellite in the inter-satellite optical communication to the earth station,
• wherein the establishing comprises performing inter-satellite optical communication based on a predetermined communication schedule and upon receiving a communication request for a satellite from the earth station, using spare time in the communication schedule to establish inter-satellite optical communication with the satellite.

A data relay method implemented by a relay satellite, the method comprising:

• transmitting, in response to a communication request for a satellite received from an earth station, an optical beacon to the satellite;
• receiving a response signal from the satellite detecting the optical beacon;
• establishing inter-satellite optical communication with the satellite based on reception of the response signal;
• and
• relaying data received from the satellite in the inter-satellite optical communication to the earth station,
• wherein the establishing comprises performing inter-satellite optical communication based on a predetermined communication schedule and upon receiving a communication request for a satellite from the earth station, establishes inter-satellite optical communication with the satellite with priority over the communication schedule.

A data relay method implemented by a relay satellite, the method comprising:

• performing inter-satellite optical communication based on a predetermined communication schedule;
• upon receiving a communication request for a satellite received from an earth station, determining an instantly responsive communication time that is not scheduled in the predetermined communication schedule;
• in response to the communication request, transmitting an optical beacon to the satellite;
• receiving a response signal from the satellite detecting the optical beacon;
• establishing inter-satellite optical communication with the satellite based on reception of the response signal;
• receiving data from the satellite in the inter-satellite optical communication within the instantly responsive communication time;
• and
• relaying the data to the earth station.

A relay satellite, comprising:

• a communicator that communicates with an earth station;
• an optical signal transceiver that transmits an optical beacon to a satellite and receives a response signal from the satellite detecting the optical beacon;
• an optical communicator that in response to the response signal, establishes inter-satellite optical communication with the satellite based on a predetermined communication schedule;
• and
• a communication controller that receives data from the satellite in the inter-satellite optical communication and uses the communicator to relay the data to the earth station,
• wherein in response to a communication request for the satellite received from the earth station, the optical signal transceiver transmits the optical beacon to the satellite, and in response to the communication request, the optical communicator further determines an instantly responsive communication time that is not scheduled in the predetermined communication schedule to establish inter-satellite optical communication with the satellite in the instantly responsive communication time.

A data relay method implemented by a relay satellite, the method comprising:

• performing inter-satellite optical communication based on a predetermined communication schedule;
• upon receiving a communication request for a satellite received from an earth station, determining an instantly responsive communication time with priority over the predetermined communication schedule;
• in response to the communication request, transmitting an optical beacon to the satellite;
• receiving a response signal from the satellite detecting the optical beacon;
• establishing inter-satellite optical communication with the satellite based on reception of the response signal;
• receiving data from the satellite in the inter-satellite optical communication within the instantly responsive communication time;
• and
• relaying the data to the earth station.

A relay satellite, comprising:

• a communicator that communicates with an earth station;
• an optical signal transceiver that transmits an optical beacon to a satellite and receives a response signal from the satellite detecting the optical beacon;
• an optical communicator that in response to the response signal, establishes inter-satellite optical communication with the satellite based on a predetermined communication schedule;
• and
• a communication controller that receives data from the satellite in the inter-satellite optical communication and uses the communicator to relay the data to the earth station,
• wherein in response to a communication request for the satellite received from the earth station, the optical signal transceiver transmits the optical beacon to the satellite, and in response to the communication request, the optical communicator further determines an instantly responsive communication time with priority over the predetermined communication schedule to establish inter-satellite optical communication with the satellite in the instantly responsive communication time.