Abstract
We discuss the use of orthogonal frequency-division multiplexing (OFDM)
for combating group-velocity dispersion (GVD) effects in amplified
direct-detection (DD) systems using single-mode fiber. We review known OFDM
techniques, including asymmetrically clipped optical OFDM (ACO-OFDM),
DC-clipped OFDM (DC-OFDM) and single-sideband OFDM (SSB-OFDM), and derive a
linearized channel model for each technique. We present an iterative
procedure to achieve optimum power allocation for each OFDM technique, since
there is no closed-form solution for amplified DD systems. For each
technique, we minimize the optical power required to transmit at a given bit
rate and normalized GVD by iteratively adjusting the bias and optimizing the
power allocation among the subcarriers. We verify that SSB-OFDM has the best
optical power efficiency among the different OFDM techniques. We compare
these OFDM techniques to on-off keying (OOK) with maximum-likelihood
sequence detection (MLSD) and show that SSB-OFDM can achieve the same
optical power efficiency as OOK with MLSD, but at the cost of requiring
twice the electrical bandwidth and also a complex quadrature modulator. We
compare the computational complexity of the different techniques and show
that SSB-OFDM requires fewer operations per bit than OOK with MLSD.
© 2010 IEEE
PDF Article
More Like This
Cited By
You do not have subscription access to this journal. Cited by links are available to subscribers only. You may subscribe either as an Optica member, or as an authorized user of your institution.
Contact your librarian or system administrator
or
Login to access Optica Member Subscription