A QoS-Aware Dynamic Bandwidth Allocation Algorithm for Passive Optical Networks with Non-Zero Laser Tuning Time

Abstract

The deployment of new 5G services and future demands for 6G make it necessary to increase the performance of access networks. This challenge has prompted the development of new standardization proposals for Passive Optical access Networks (PONs) that offer greater bandwidth, greater reach and a higher rate of aggregation of users per fiber, being Time- and Wavelength-Division Multiplexing (TWDM) a promising technological solution for increasing the capacity by up to 40 Gbps by using several wavelengths. This solution introduces tunable transceivers into the Optical Network Units (ONUs) for switching from one wavelength to the other, thus addressing the ever-increasing bandwidth demands in residential broadband and mobile fronthaul networks based on Fiber to the Home (FTTH) technology. This adds complexity and sources of inefficiency, such as the laser tuning time (LTT) delay, which is often ignored when evaluating the performance of Dynamic Bandwidth Allocation (DBA) mechanisms. We present a novel DBA algorithm that dynamically handles the allocation of bandwidth and switches the ONUs’ lasers from one wavelength to the other while taking LTT into consideration. To optimize the packet delay, we introduce a scheduling mechanism that follows the Longest Processing Time first (LPT) scheduling discipline, which is implemented over the Interleaved Polling with Adaptive Cycle Time (IPACT) DBA. We also provide quality of service (QoS) differentiation by introducing the Max-Min Weighted Fair Share Queuing principle (WFQ) into the algorithm. The performance of our algorithm is evaluated through simulations against the original IPACT algorithm, which we have extended to support multi-wavelengths. With the introduction of LPT, we obtain an improved performance of up to 73% reduction in queue delay over IPACT while achieving QoS differentiation with WFQ.

A Distance-Weighted Dynamic Bandwidth Allocation Algorithm for Improved Performance in Long-Reach Passive Optical Networks for Next Generation Networks

“…Self-similar traffic [34] is generated by the traffic sources with a Hurst parameter H = 0.75, and the mean packet rate is adjusted based on the changing offered load. To realistically model Ethernet traffic, the frame size is uniformly distributed with a lower limit of 512 bits and an upper limit of 12,144 bits, as stated in [14].…”

“…Newer generations of PONs utilize multiple wavelengths through techniques such as Time and Wavelength Division Multiplexing (TWDM) [13,14]. This method is increasingly being used in the deployment of new LRPON systems to increase the capacity and bandwidth of PON systems.…”

“…In TWDM-based LRPON systems, tunable transceivers empower ONUs to switch between multiple wavelengths, improving the network flexibility and maximizing bandwidth utilization [14]. To efficiently manage shared resources, a sophisticated DBA scheme is employed, facilitating wavelength and time slot allocation for ONUs in TWDM LRPONs.…”

“…This involves wavelength switching at the ONUs and the dynamic assignment of time slots for upstream bandwidth sharing. However, the integration of tunable devices introduces complexities and potential delays due to the Laser Tuning Time (LTT) during wavelength switching [14]. The LTT, which is often overlooked, can impact the system performance.…”

Dynamic Spectrum Assignment in Passive Optical Networks Based on Optical Integrated Microring Resonators Using Machine Learning and a Routing, Modulation Level, and Spectrum Assignment Method

“…Despite their potential to enhance the network efficiency, the significant separation between wavelengths (200 GHz, 100 GHz, and 50 GHz) limits optimal spectrum utilization, particularly for requests that require a low transfer rate-as is the case for Internet of Things (IoT) devices. Additionally, these approaches do not account for the use of different multi-level modulation formats, which could help to reduce the portion of the spectrum needed [10,11].…”