Electronic Dispersion Pre-Compensation in PM-QPSK Systems over   Mixed-Fiber Links
  Dispersion pre-compensation is shown to potentially lead to a substantial non-linearity reduction in PM-QPSK links that use a mixture of high and low dispersion fibers. However, the much larger PAPR of the pre-compensated signal poses challenging requirements on the transmitter. 
A. Carena, Y. Jiang, P. Poggiolini, G. Bosco, V. Curri, F. Forghieri
physics.optics