OFDMA-PON with MQAM downlink for flexible allocation

In this paper, the 40-Gbps orthogonal frequency division multiple access (OFDMA) technology enabled by subcarrier allocation in the form of integrated architecture for the intra-cell is proposed in the downlink transmission passive broadband optical access system. The data-carrying subcarriers in the inverse fast Fourier transform/fast Fourier transform (IFFT/FFT) size of 1 024 points are successfully divided into three sub-channels, in which each sub-channel has 256 useful subcarriers, by using adaptive dynamic bandwidth allocation (DBA). Taking the inherent advantages of M-ary quadrature amplitude modulation (MQAM) modulation mechanism into account, the performance of the absolutely identical MQAM format over the different sub-channels for the downstream OFDMA-passive optical network (PON) is investigated based on the intensity modulation direct detection (IMDD) system by simulations. The results show that three parallel 4QAM or 16QAM or 64QAM OFDMA data, which are transmitted over three sub-channels, is more suitable for different sub-channel allocations, respectively. In addition, comparing with single port 4/16/64QAM OFDM over the same access system, the receiver sensitivity economizes -0.6 dBm, 0.6 dBm, 4.6 dBm at the bit error rate (BER) value of 10^-3 respectively.