Equalization apparatus, optical transmission system, and equalization method

1 . An equalization apparatus, comprising:

at least one memory configured to store instructions; and

at least one processor configured to execute the instructions to cause the equalization apparatus to:

perform a process associated with a signal using a transfer function with a coefficient, the signal propagating through each of at least three channels; and

generate the coefficient based on channel quality information on each of the at least three channels,

process first data and second data into a first processed signal and a second processed signal using a first transfer matrix as the transfer function,

wherein a coefficient of the first transfer matrix is a coefficient that gives more signal power to a channel with a lowest channel quality among the channels selected, in such a way to reduce a difference of quality between the channel with the lowest channel quality and the channel with a highest channel quality,

wherein the first processed signal is to be transmitted through a first channel of the at least three channels,

wherein the second processed signal is to be transmitted through a second channel of the at least three channels, and

wherein one of the first channel and the second channel is the channel with the lowest channel quality, and the other is the channel with the highest channel quality.

2 . The equalization apparatus according to claim 1 ,

wherein the at least one processor is further configured to execute the instructions to cause the equalization apparatus to:

restore the first processed signal after propagating through the first channel and the second processed signal after propagating through the second channel to the first data and the second data, using a second transfer matrix as the transfer function, and

wherein the second transfer matrix is an inverse matrix of the first transfer matrix.

3 . The equalization apparatus according to claim 2 , wherein the at least one processor is further configured to execute the instructions to cause the equalization apparatus to:

select the first processed signal for the first channel, select the second processed signal for the second channel, and select other data for other channel of the at least three channels, and

select the first data and the second data obtained by restoring the first processed signal and the second processed signal, and select the other data propagating through the other channel.

4 . An equalization apparatus, comprising:

at least one memory configured to store instructions; and

at least one processor configured to execute the instructions to cause the equalization apparatus to:

perform a process associated with a signal using a transfer function with a coefficient, the signal propagating through each of at least three channels;

generate the coefficient based on channel quality information on each of the at least three channels;

process first data and second data into a first processed signal and a second processed signal using a first transfer matrix as the transfer function,

wherein a coefficient of the first transfer matrix is a coefficient that gives more signal power to a channel with a lowest channel quality among the channels selected, in such a way to reduce a difference of quality between the channel with the lowest channel quality and the channel with a highest channel quality,

wherein the at least one processor is further configured to execute the instructions to cause the equalization apparatus to:

select the first processed signal for a first channel of the at least three channels, and select the second processed signal for a second channel of the at least three channels, and

wherein one of the first channel and the second channel is the channel with the lowest channel quality, and the other is the channel with the highest channel quality.

5 . The equalization apparatus according to claim 4 , wherein the at least one processor is further configured to execute the instructions to cause the equalization apparatus to:

select the first processed signal after propagating through the first channel and the second processed signal after propagating through the second channel,

restore the first processed signal and the second processed signal selected to the first data and the second data, using a second transfer matrix as the transfer function, and

wherein the second transfer matrix is an inverse matrix of the first transfer matrix.

6 . An equalization method, comprising:

performing a process associated with a signal using a transfer function with a coefficient, the signal propagating through each of at least three channels; and

generating the coefficient based on channel quality information on each of the at least three channels,

wherein the generating of the coefficient includes measuring channel quality of each of the at least three channels,

wherein a coefficient of the transfer function is a coefficient that gives more signal power to a channel with a lowest channel quality among the channels selected, in such a way to reduce a difference of quality between the channel with the lowest channel quality and the channel with a highest channel quality, and

wherein the performing of the process associated with the signal includes processing data to be transmitted through channels having a difference in the channel quality between the channel with the lowest channel quality and the channel with the highest channel quality in such a way as to give more signal power to the channel with lowest channel quality.