Traffic Performance of an Access Hybrid WDM/TDM PON with Colorless Reflective-ONUs under Different Distances OLT-ONUs

To reduce costs and cumbersome laser provisioning at the Optical Network Unit (ONU) user level in an access Passive Optical Network (PON), the use of a Reflective-ONU (R-ONU) is a good choice for up-data transmission. An optical carrier is sent by the Optical Line Terminal (OLT) at the Central Office, and a device at the ONU modulates the carrier with the upstream data. This allows all ONUs to be equal and colorless, without a light source in a Hybrid WDM/TDM architecture. The Dynamic Bandwidth Allocation (DBA) is placed at the OLT, where lasers and photodetectors are shared by all R-ONUs. The OLT laser and photodetector employed in an up-data transmission must be tuned for each ONU and a particular Round Trip Time (RTT) set, which is twice the propagation time from OLT to ONU. When an R-ONU is served by a laser, the photodetector must also be available after the RTT to demodulate the up-data. We investigate the importance of the impact of large different distances OLT-ONUs in the traffic characteristics under a DBA with a proposed novel nesting algorithm and Quality of Service (QoS).