Efficient upstream bandwidth utilization with minimum bandwidth waste for time and wavelength division passive optical network

摘要

For an efficient bandwidth management among the optical network units in the upstream link of a passive optical network (PON), it is necessary to use a dynamic bandwidth assignment (DBA) scheme at the optical line terminal. This is really helpful for the PON service providers in meeting their delay guarantees and bandwidth commitments as per the service level agreements (SLAs). It also enables them to increase their revenue by accommodating more users in the available bandwidth. This study investigates the weaknesses of existing ITU compliant DBA schemes. The study reviews the earlier reported work on DBA with a focus on the ITU compliant schemes. The study argues that the existing reported schemes suffer from a few deficiencies such as inefficient bandwidth reporting in their polling process and borrow refund problem while utilizing the unused bandwidth (UBW). To overcome these shortcomings, an efficient bandwidth assignment (EBA) scheme is presented. Extensive simulations are performed to test the performance of the proposed scheme with both Poisson distributed and self-similar traffic patterns. The results show that the EBA scheme efficiently utilizes the UBW and RSB leading up to 80%, 90%, 60% and 99% lesser upstream delays with Poisson traffic pattern and up to 80%, 77% and 99% lesser delay with self-similar traffic compared to GREAL, IACG, and GIANT schemes. However, compared to EBU it shows up to 12% higher delay values due to reduction of its RSB share because of the utilization of UBW by T3 and T4. Overall, compared to other schemes, EBA exhibits least bandwidth waste per cycle resulting in least US delays. The bandwidth waste in EBA is also minimized due to least unallocated bandwidth ratio and frame loss rate. The maximum US delays of all traffic classes for EBA remains under 2 ms for T2 and T3 till the traffic load of 1 and till the load of 0.8 for T4 traffic class.