Performance analysis of next generation 3-D OFDM based optical access networks under various system impairments

Passive optical network (PON) based on orthogonal frequency division multiplexing (OFDM-PON) is a promising candidate for high optical access network due to its greater resistance to fiber dispersion. High spectral efficiency is also achieved due to the orthogonality among all sub-carriers which overlap in the frequency domain. Two-dimensional (2-D) signal mapper and one-dimensional (1-D) inverse fast fourier transform (IFFT) are the major elements of the conventional OFDM communication system. In this paper, we use the concept of three-dimensional (3-D) signal mapper and 2-D IFFT which is called as 3-D OFDM communication system. The performance of 40 Gb/s 2-D OFDM-PON and 3-D OFDM-PON using multi-level modulation scheme under various system impairments is analytically analyzed for coherent optical orthogonal frequency division multiplexing (CO-OFDM) without using any optical dispersion compensation. As bit error rate (BER) depends on minimum Euclidean distance (MED) which is 15.46 % more in case of 3-D OFDM as compared to 2-D OFDM. Analytical result show that at BER of 10^-3 which is the limit of forward error correction (FEC), there is about 2.5 dB signal-to-noise ratio (SNR) gain. An optical budget (downstream) of 47.1 dB is obtained for 40 Gb/s optical access networks using 2-D OFDM and about 48.4 dB for 3-D OFDM with 16-QAM and corresponding values are 45.3 dB and 46.5 dB respectively for 64-QAM.