Patent ID: 8699625
Filing Date: 2014-04-15
Classification: H04L

Abstract:
1. A high speed optical transport network, comprising: one or more low-density parity-check (LDPC) encoders each receiving a source channel; an interleaver coupled to the LDPC encoders; an N-dimensional mapper coupled to the interleaver; an inverse FFT (IFFT) block coupled to the N-dimensional mapper to generate N-dimensional pulse-amplitude modulation (ND-PAM) signal constellation points' coordinates; a cyclic extension insertion and parallel to serial (P/S) conversion block coupled to the IFFT block; means for adding all coordinates, upon multiplication with exp[j2nkt/T], to provide real and imaginary parts of a signal used as in-phase and quadrature signals for Mach-Zehnder modulators (MZMs); wherein an FFT block provides projections along subcarrier basis functions, and where a kth FFT output represents the projection along a kth coordinate; and wherein an a posteriori probability (APP) demapper comprises a symbol log-likelihood ratio (LLR) calculator to determine