Communication device, communication method, and communication program

1. A communication device comprising:

circuitry configured to:

based on information on a transmission characteristic of a free-space optical communication used for transmitting data, determine an interleaving length of the data;

interleave the data based on the determined interleaving length; and

transmit the interleaved data,

wherein the interleaving length is changeable, 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 circuitry is configured to shape the interleaved data based on a data format configured to make the interleaving length detectable on a receiving side of the free-space optical communication.

3. The communication device according to claim 2 , wherein

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

the circuitry is configured to dispose at least two types of the synchronization codes in the 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 at least two types of the synchronization codes includes:

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 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, a product code or a Reed-Solomon product code.

7. 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.

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

9. The communication device according to claim 1 , wherein

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

10. A communication device comprising:

circuitry configured to

received data through a free-space optical communication;

detect an interleaving length of the received data; and

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 data,

wherein the interleaving length is changeable;

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.

11. The communication device according to claim 10 , 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.

12. The communication device according to claim 11 , wherein the information on a transmission characteristic further comprises information on an error rate of the free-space optical communication.

13. A communication method performed by a communication device including a processor, the method comprising:

based on information on a transmission characteristic of a free-space optical communication used for transmitting data, determining an interleaving length of the data;

interleaving the data based on the determined interleaving length; and

transmitting the interleaved data,

wherein the interleaving length is changeable, 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.

14. The method according to claim 13 , 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.

15. The method according to claim 14 , wherein the information on a transmission characteristic further comprises information on an error rate of the free-space optical communication.