| 摘要 |
An optical sender is disclosed that operates in a Differential Quadrature Phase Shift Keying modulation scheme for high speed optical transmission and is capable of performing logical calculations at a low speed. The optical sender transmits a Differential Quadrature Phase Shift Keying (DQPSK) signal generated with modulation signals rho<SUB>k </SUB>and eta<SUB>k </SUB>so that a signal directly output from a signal receiver corresponding to the optical sender is in agreement with data signals I<SUB>k </SUB>and Q<SUB>k </SUB>to be transmitted. The signal receiver is capable of modulation by DQPSK, and the modulation signals rho<SUB>k </SUB>and eta<SUB>k </SUB>are precoded by using the data signals I<SUB>k </SUB>and Q<SUB>k </SUB>and the modulation signals one symbol earlier (rho<SUB>k-1 </SUB>and eta<SUB>k-1</SUB>) . The optical sender includes plural precoders that perform logical calculation simultaneously and in parallel on plural data signals one period after another period.
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