Communication device, communication method, and communication program

1. A communication device comprising:

interleaving circuitry configured to determine an interleaving length of transmit data to be transmitted through free-space optical communication, and interleave the transmit data based on the determined interleaving length; and

shaping circuitry configured to shape the interleaved transmit data so as to make the interleaving length detectable on a receiving side of the free-space optical communication,

wherein the interleaving circuitry is configured to determine the interleaving length based on information on a transmission characteristic of the free-space optical communication used for transmitting the transmit data, and

wherein the information on a transmission characteristic comprises information indicating that the free-space optical communication is:

communication performed between a ground station and a satellite station, or

communication performed between satellite stations, or

communication performed between ground stations.

2. The communication device according to claim 1 , wherein the shaping circuitry is configured to shape the interleaved transmit data based on a data format configured to make the interleaving length detectable on the receiving side of the free-space optical communication.

3. The communication device according to claim 2 , wherein

the data format is such that the transmit data includes synchronization codes, and

the shaping circuitry is configured to dispose at least two types of the synchronization codes in the transmit data so as to make the interleaving length detectable on the receiving side of the free-space optical communication.

4. The communication device according to claim 3 , wherein the shaping circuitry is configured to dispose either of a first synchronization code representing a start point or an end point of the interleaving and a second synchronization code representing a continuation point of the interleaving at intervals of a predetermined data length based on the determined interleaving length.

5. The communication device according to claim 4 , wherein

the data format is a block format including one or a plurality of data blocks,

the block format includes the data block or blocks each with a synchronization code disposed at a block boundary thereof, and

the shaping circuitry is configured to dispose either of the first synchronization code and the second synchronization code at the block boundary based on the determined interleaving length.

6. The communication device according to claim 5 , wherein the block format is a format including an error correction block encoded using a block code.

7. The communication device according to claim 6 , wherein the block format is a format including an error correction block encoded using a product code.

8. The communication device according to claim 7 , wherein the block format is a format including an error correction block encoded using a Reed-Solomon product code.

9. The communication device according to claim 1 , wherein:

based on the information on the transmission characteristic indicating that the free-space optical communication is the communication performed between the satellite stations, the interleaving length is determined to be a first interleaving length;

based on the information on the transmission characteristic indicating that the free-space optical communication is the communication performed between the ground station and the satellite station, the interleaving length is determined to be a second interleaving length longer than the first interleaving length; and

based on the information on the transmission characteristic indicating that the free-space optical communication is the communication performed between the ground stations, the interleaving length is determined to be a third interleaving length longer than the first interleaving length and shorter than the second interleaving length.

10. The communication device according to claim 1 , wherein the information on a transmission characteristic further comprises information on an error rate during the communication with the receiving side of the free-space optical communication.

11. The communication device according to claim 1 , wherein

the transmit data includes, in addition to first data serving as payload data, second data used for exchanging control information between communication devices for the free-space optical communication, and

the interleaving circuitry is configured to determine the interleaving length based on the second data.

12. A communication device comprising:

detection circuitry configured to detect an interleaving length of received data that has been received through free-space optical communication and has been shaped such that the interleaving length is detectable therefrom; and

deinterleaving circuitry configured to deinterleave the received data based on the detected interleaving length,

wherein the interleaving length is based on information on a transmission characteristic of the free-space optical communication used for transmitting the transmit data, and

wherein the information on a transmission characteristic comprises information indicating that the free-space optical communication is:

communication performed between a ground station and a satellite station, or

communication performed between the satellite stations, or

communication performed between ground stations.

13. The communication device according to claim 12 , wherein:

based on the information on the transmission characteristic indicating that the free-space optical communication is the communication performed between the satellite stations, the interleaving length is determined to be a first interleaving length;

based on the information on the transmission characteristic indicating that the free-space optical communication is the communication performed between the ground station and the satellite station, the interleaving length is determined to be a second interleaving length longer than the first interleaving length; and

based on the information on the transmission characteristic indicating that the free-space optical communication is the communication performed between the ground stations, the interleaving length is determined to be a third interleaving length (longer than the first interleaving length and shorter than the second interleaving length.

14. The communication device according to claim 12 , wherein the information on a transmission characteristic further comprises information on an error rate during the communication with the receiving side of the free-space optical communication.

15. A communication method comprising:

determining an interleaving length of transmit data to be transmitted through free-space optical communication;

interleaving the transmit data at the determined interleaving length; and

shaping the interleaved transmit data so as to make the interleaving length detectable on a receiving side of the free-space optical communication,

wherein the interleaving circuitry is configured to determine the interleaving length based on information on a transmission characteristic of the free-space optical communication used for transmitting the transmit data, and

wherein the information on a transmission characteristic comprises information indicating that the free-space optical communication is:

communication performed between a around station and a satellite station, or

communication performed between the satellite stations, or

communication performed between around stations.

16. The method according to claim 15 , wherein:

based on the information on the transmission characteristic indicating that the free-space optical communication is the communication performed between the satellite stations, the interleaving length is determined to be a first interleaving length;

based on the information on the transmission characteristic indicating that the free-space optical communication is the communication performed between the ground station and the satellite station, the interleaving length is determined to be a second interleaving length longer than the first interleaving length; and

based on the information on the transmission characteristic indicating that the free-space optical communication is the communication performed between the ground stations, the interleaving length is determined to be a third interleaving length (longer than the first interleaving length and shorter than the second interleaving length.

17. The method according to claim 15 , wherein the information on a transmission characteristic further comprises information on an error rate during the communication with the receiving side of the free-space optical communication.

18. A non-transitory computer readable medium containing instructions for causing a computer to function as:

interleaving circuitry that determines an interleaving length of transmit data to be transmitted through free-space optical communication, and interleaves the transmit data at the determined interleaving length; and

shaping circuitry that shapes the interleaved transmit data so as to make the interleaving length detectable on a receiving side of the free-space optical communication,

wherein the interleaving circuitry is configured to determine the interleaving length based on information on a transmission characteristic of the free-space optical communication used for transmitting the transmit data, and

wherein the information on a transmission characteristic comprises information indicating that the free-space optical communication is:

communication performed between a ground station and a satellite station, or

communication performed between the satellite stations, or

communication performed between ground stations.

19. The non-transitory computer readable medium according to claim 18 , wherein:

based on the information on the transmission characteristic indicating that the free-space optical communication is the communication performed between the satellite stations, the interleaving length is determined to be a first interleaving length;

based on the information on the transmission characteristic indicating that the free-space optical communication is the communication performed between the ground station and the satellite station, the interleaving length is determined to be a second interleaving length longer than the first interleaving length; and

based on the information on the transmission characteristic indicating that the free-space optical communication is the communication performed between the ground stations, the interleaving length is determined to be a third interleaving length (longer than the first interleaving length and shorter than the second interleaving length.

20. The non-transitory computer readable medium according to claim 18 , wherein the information on a transmission characteristic further comprises information on an error rate during the communication with the receiving side of the free-space optical communication.