The goal of this document is to analyse the functionality of Passive Optical Networks (PONs). The reason for focusing on these technique networks is due to their high efficiency in terms of high bandwidth, high rate, low energy consumption and low cost. PONs are composed of Optical Network Unit (ONU), Optical Line Terminal (OLT) and passive elements (splitters/combiners, optical fibres…). Specifically, this document analyses Ethernet Passive Optical Networks (EPONs) defined by Institute of Electrical and Electronics Engineers (IEEE) in the IEEE 802.3ah standard although there is another standard. The main difference between them is the framing protocol, being the EPONs compliance with Ethernet frames. The first PONs used a single optical carrier. That means that upstream channel is a shared resource and a scheduling is needed to avoid collisions between users’ transmissions, by using Time-Division Multiple Access (TDMA). In PONs the OLT plays an important paper, since it is the responsible of the dynamic bandwidth allocation (DBA). The DBA agent in the OLT has an algorithm that schedules the users’ transmissions. Since the deployment of the first PONs, the requirements of the users have increased, and users need high bandwidth and high rate. Thus, a new generation of PONs (NG-PON) have been designed. These next generation of PONs are multicarrier. That means that upstream channel that is a shared resource needs a Medium Access Protocol (MAC) based on wavelength/time-sharing known as Wavelength-Time Division Multiple Access (WTDMA). The algorithm placed on the DBA agent in the OLT increases its complexity. The algorithm should be able to schedule the transmissions based on time and wavelength. In the new generation of PON, in order to change the transmission wavelength, the ONUs have to retune their lasers. This wavelength change causes a tuning time delay. The target of this project is to design, implement and analyse an algorithm based on WTDMA and able to consider the tuning time delay and to minimize the global average delay of the system. Besides, the algorithm should apply the Just-In-Time (JIT) technique for increasing the system efficiency. All the simulations and implementations have been performed in the OPNET simulator, over a base code based on multicarrier EPON created by another student. In order to implement our algorithm a previous upgrading work has been realized for running the model and adapting it for the new requirements. We have succeeded in simulating an EPON with 4 channels where every channel has a 1 Gbps of bandwidth in OPNET simulator. In EPON we have introduced a laser tuning time control. Finally, we have implemented the designed algorithm. The algorithm schedules efficiently the network transmissions considering the laser tuning time delay. We have successfully simulated an EPON with 4 carriers, with 1 Gbps per carrier. Finally, we have implemented an algorithm able to schedule efficiently the network transmissions considering the laser tuning time delay
