US 11,736,127 B2
Optical transmission device and likelihood generation circuit
Yoshiaki Konishi, Tokyo (JP); Kenji Ishii, Tokyo (JP); Hideo Yoshida, Tokyo (JP); Takashi Sugihara, Tokyo (JP); and Tsuyoshi Yoshida, Tokyo (JP)
Assigned to MITSUBISHI ELECTRIC CORPORATION, Tokyo (JP)
Filed by MITSUBISHI ELECTRIC CORPORATION, Tokyo (JP)
Filed on Aug. 18, 2021, as Appl. No. 17/405,461.
Application 17/405,461 is a continuation of application No. PCT/JP2019/009621, filed on Mar. 11, 2019.
Prior Publication US 2021/0384921 A1, Dec. 9, 2021
Int. Cl. H03M 13/45 (2006.01); H04B 10/61 (2013.01); H04L 27/38 (2006.01)
CPC H03M 13/45 (2013.01) [H04B 10/6165 (2013.01); H04L 27/38 (2013.01)] 2 Claims
OG exemplary drawing
 
1. An optical reception device, comprising:
a symbol demapping circuitry to convert reception signals, which are acquired via transmission over an optical transmission line, said reception signals being selectively modulated for transmission according to
low-order rectangular QAM,
low-order non-rectangular QAM, and
high-order non-rectangular QAM,
to a signal of an I-axis component and a signal of a Q-axis component on a phase plane, and a signal being a concatenation of the signal of the I-axis component and the signal of the Q-axis component;
a likelihood generating circuitry to generate likelihoods relating to each of the reception signals based on the corresponding signal of the I-axis component and the corresponding signal of the Q-axis component converted by the symbol demapping circuitry and on the signal being the concatenation of the signal of the I-axis component and the signal of the Q-axis component; and
an error correction decoding circuitry to execute soft decision decoding on each of the reception signals based on the likelihoods generated by the likelihood generating circuitry,
wherein the likelihood generating circuitry includes:
a first one-dimensional-modulation lookup table configured to input the signal of the I-axis component of each of the reception signals as an argument to output a first likelihood;
a second one-dimensional-modulation lookup table configured to input the signal of the Q-axis component of each of the reception signals as an argument to output a second likelihood; and
a two-dimensional-modulation lookup table configured to input, as an argument, the signal being the concatenation of the signal of the I-axis component and the signal of the Q-axis component of each of the reception signals, to generate a third likelihood, and
wherein the error correction decoding circuitry is configured to execute the soft decision decoding based on the first likelihood, the second likelihood, and the third likelihood,
wherein the first one-dimensional-modulation lookup table and the second one-dimensional-modulation lookup table are used for the likelihood generation for each of the reception signals modulated according to the low-order rectangular QAM,
wherein the two-dimensional-modulation lookup table is used for the likelihood generation for each of the reception signals modulated according to the low-order non-rectangular QAM, and
wherein the first one-dimensional-modulation lookup table, the second one-dimensional-modulation lookup table, and the two-dimensional-modulation lookup table are shared to be used for the likelihood generation for each of the reception signals modulated according to the high-order non-rectangular QAM.