| 摘要 |
PROBLEM TO BE SOLVED: To reduce a PAPR in a QAM multi-value signal greater than or equal to QPSK.SOLUTION: A digital signal processing circuit 1 includes: a bit-data generating circuit 11; a mapper circuit 12 converting bit data into a multi-value signal of an Ich signal and a Qch signal; and DACs 13 digital/analog-converting the Ich signal and the Qch signal. An optical transmitter 2 has a light source 22 outputting light functioning as a transmission carrier, an optical I/Q modulator 23 modulating the light by using transmission electric signals outputted from the DACs 13, and an SOA 24 amplifying the optical signal outputted from the optical I/Q modulator. The mapper circuit 12 has two kinds of mappers of a map (a) and a map (b), and performs modulation by alternately switching the two kinds of mappers for each transmission timing of the bit data. |
