Enhancing The QoS in Energy Efficient Wdm/OFDM Passive Optical Networks

In this paper, we propose new methodology to enhance the QoS in cost and energy efficient WDM/OFDM PON system. In this, the WDM technique supports more number of ONU and the OFDM technique provides high spectral efficiency and flexible sub-channel bandwidth allocation. Here, we have reduce BER at ONU by using the post dispersion compensation technique inorder to reduce the chromatic dispersion which is a major issue in single mode fiber, when signal travels for a long distance. Also the DCF supports high data rate and long distance transmission. Cost efficiency can be achieved by using the arrayed waveguide grating instead of using WDM MUX/DEMUX and unpowered passive optical device. In WDM/OFDM PON system, 4-QAM is used because it is not that much susceptible to noise when compare to higher order modulation schemes. By using this, here we can increase the quality factor thereby the bit error rate gets decreases. The higher the quality factor indicates the better signal to noise ratio.