Digital coherent quadrature phase-shift-keying (QPSK)
U.-V. Koc, A. Leven, Y. Chen, Noriaki Kaneda · 2006
Conventional coherent detection attempts to synchronize local lasers with transmit lasers indiscriminately without considering individual noise contributors. Handling each contributor properly, we proposed a novel approach for quadrature-phase-shift-keying to enable realization of coherent communication without need of synchronization