Ship-centric direct communication system and operation method thereof

A method of operating a ship-centric direct communication system, the method comprising:

• transmitting, by a data transmission device to a data reception device through a link channel, a transmission frame composed of a plurality of slots generated according to slot time, a plurality of pilots provided for channel estimation and arranged in each of a front, middle, and back of the plurality of slots according to a pilot transmission period, and data symbols arranged between each of the plurality of pilots;
• performing, by the data reception device, channel compensation for data present between the plurality of pilots by using the plurality of pilots for each of the plurality of slots of the transmission frame in receiving the transmission frame and by performing linear interpolation after the channel estimation in a frequency domain;
• and
• converting, by the data reception device, channel-compensated signals back into time domain symbols,
• wherein performing, by the reception device, the channel compensation for the data present between the plurality of pilots by performing the linear interpolation after the channel estimation in the frequency domain includes,
• performing, for a first pilot, a first linear interpolation after the channel estimation in the frequency domain by using a first noise variance σ1 obtained from the first pilot and a first least squares (LS) operation result H1 obtained from the first pilot,
• performing, for a second pilot, a second linear interpolation after the channel estimation in the frequency domain by using a second noise variance σ2 obtained from the second pilot and a second LS operation result H2 obtained from the second pilot, and
• performing, for a third pilot, a third linear interpolation after the channel estimation in the frequency domain by using a third noise variance σ3 obtained from the third pilot and a third LS operation result H3 obtained from the third pilot,
• wherein a fourth liner interpolation results H12 determined from a time the first pilot is received until a time when the second pilot is received is calculated by using the first LS operation results H1, the second LS operation result H2, and a first number C1 obtained by adding 1 to a first number of data symbols between the first pilot and the second pilot,
• wherein a fifth linear interpolation result H23 determined from a time the second pilot is received until a time the third pilot is received is calculated by using the second LS operation result H2 the third LS operation result H3, and a second number C2 obtained by adding 1 to a second number of data symbols between the second pilot and the third pilot,
• wherein a fourth noise variance σ12 is calculated by using the first noise variance σ1, the second noise variance σ2, and a third number C3 obtained by adding 1 to a third number of data symbol between the first pilot and the second pilot,
• wherein a fifth noise variance σ23 is calculated by using the second noise variance σ2, the third noise variance σ3, and a fourth number C4 obtained by adding 1 to a number of data symbols between the second pilot and the third pilot.