Performance Analysis of Dynamic Wavelength Allocation Algorithm for TWDM PON with Inexpensive ONUs

In this paper, we introduce a new dynamic wavelength allocation algorithm for a TWDM PON (time and wavelength division multiplexed passive optical network) having inexpensive ONUs (optical network units). The inexpensive ONU has a cheap and low-speed wavelength tuner. The cheap tuner takes from few milliseconds to few seconds to change its wavelength. Most dynamic wavelength allocation algorithms assume that an ONU has a perfect tuner whose tuning time is zero. Unlike most existing algorithms, the proposed algorithm does not ignore the tuning time of an ONU tuner. In the proposed algorithm, an OLT (optical line termination) uses an average grant amount to predict the average packet arrival rates of all ONUs. The OLT decreases the number of active upstream wavelengths if the average grant amount is less than the bandwidth amount of the upstream wavelengths. Otherwise, the OLT increases the number of active upstream wavelengths. Using computer simulations, we show performance of the proposed algorithm and the average number of active upstream wavelengths.