Reach Passive Optical Networks Research Articles

FBMC-based dispersion compensation using artificial neural network equalization for long reach-passive optical network

This paper presents a Filter Bank Multicarrier (FBMC), a viable waveform candidate for fifth generation (5G) communications using Staggered-Modulated Multitone (SMT). FBMC is preferred in optical communication because of its ability to work without Cyclic Prefix (CP). In any case, the operation of FBMC in optical access systems with Artificial Neural Networks (ANNs) has not been broadly explored either downstream or upstream. This work presents an advanced Nonlinear Feed-Forward Equalizer (NFFE) that makes use of multilayer ANN for dispersion compensation. ANN is trained to act as a filter with an extensive equalizer training which has the ability to mitigate dispersion and increase the performance of the system. The simulation work is used to study the performance of intensity modulated FBMC system with direct detection in Long Reach-Passive Optical Networks (LR-PONs).The transmission data rate is varied between 8 and 10[Formula: see text]Gbps with the optical fiber length from 30 to 90[Formula: see text]km of Standard Single Mode Fiber (SSMF). The obtained result suggests that FBMC system with ANN-NFFE equalizer fundamentally builds the resilience to the Chromatic Dispersion (CD) distortion, and a CP-less transmission is possible upto 90[Formula: see text]km.

Dynamic Bandwidth Allocation Scheme In Lr-Pon With Performance Modelling And Analysis

We consider models of telecommunication systems that incorporate probability, dense real-time and data. We present a new formal abstraction method for computing minimum and maximum reachability probabilities for such models. Our approach uses strictly local formal abstract steps to reduce both the size of abstract specifications generated and the complexity of operations needed, in comparison to previous approaches of this kind. A selection of large case studies are implemented the techniques and evaluate, which include some infinite-state probabilistic real time models, demonstrating improvements over existing tools in several cases. The capacity of metro and access networks are extended the reach and split ratio of the conventional Long - Reach Passive Optical Networks (LR-PONs). The efficient solutions of LR-PONs are appeared in feeder distances around 100km and high split ratios up to 1000-way . Among many existing approaches, one of the most e ffective options to improve network performance in LR-PONs are the multi-thread based dynamic bandwidth allocation (DBA) scheme where several bandwidth allocation processes are performed in parallel is considered. Without proper intercommunication between the overlapped threads, multi-thread DBA may lose e fficiency and even perform worse than the conventional single thread algorithm. Real Time Probabilistic Systems are used to evaluate a typical PON systems performance. This approach is more convenient, flexible, and lower cost than the former simulation method, which do not need develop special hardware and software tools. Moreover, how changes in performance depend on changes in the particular modes can be easily analysis by supplying ranges for parameter values. The proposed algorithm with traditional DBA is compared, and shows its advantage on average packet delay. The key parameters of the algorithm are analysed and optimized, such as initiating and tuning multiple threads, inter -thread scheduling, and fairness among users. The algorithms advantage in numerical results are decreased the average packet delay and improve network throughput under varying offered loads.

A Multi-Threaded Dynamic Bandwidth and Wavelength Allocation Scheme With Void Filling for Long Reach WDM/TDM PONs

Dynamic Bandwidth Allocation (DBA) is a major research challenge in the migration of Passive Optical Networks (PON) systems towards Long Reach PON, especially when hybrid WDM/TDM is used (LR WDM/TDM PON). New solutions for Dynamic Bandwidth and Wavelength Assignment (DBWA) are sought to address two main critical issues of such PON systems: how to schedule the transmissions over multiple wavelengths and how to efficiently exploit the bandwidth in presence of long propagation delays of long reach scenarios. In this work, for the first time, we investigate the Multi-thread polling in a LR WDM/TDM PON. Then, we propose a new DBWA scheme, called EFT-partial-VF Multi-threaded, which effectively combines some of the features of, the Earliest Finish Time with Void Filling (EFT-VF) algorithm, with the Multi-thread algorithm. The two proposed solutions, namely the MT algorithm and the EFT-partial-VF Multi-threaded algorithm, provide significant improvement in terms of average delay, if compared with existing algorithms such as the EFT and the EFT-VF. Besides this, we extend the definition of polling cycle to hybrid WDM/TDM PON and we provide a method to calculate it.

Performance analysis of ONU-wavelength grouping schemes for efficient scheduling in long reach-PONs

Long Reach PONs (LR-PON) were proposed to extend the benefits of Passive Optical Networks (PON) to more users and to a larger area. This paper considers a Dynamic Bandwidth Allocation (DBA) based on a hybrid combination of Time Division Multiplexing (TDM) and Wavelength Division Multiplexing (WDM). The time complexity of the DBA algorithm is typically O(nlogn), where n denotes the number of ONUs. Since the maximum number of supported ONUs in an LR-PON can be as high as 2048, the computation time required for computing a schedule will be very high and directly impacts the overall network performance. In this paper, we have presented a grouping strategy to reduce the computation requirements. The number of ONUs is split into mutually exclusive groups with the OLT scheduling each group independently and in parallel. With the static grouping strategy every user is assigned to a group and the assignment of wavelength resources is fixed. However, with non-uniform loads, we observed that static grouping was not found to be suitable as the delay variation was significant across the groups. To address this gap, we introduce the concept of dynamic grouping and define three dynamic grouping heuristics that adapt to the current network load conditions and (re)allocate the ONUs and wavelength resources suitably. The proposed schemes have been compared in terms of delay variation and wavelength utilization. Of the three heuristics, ONU to Least Loaded wavelength group (OLL) and Least Wavelength Resources (LWR) heuristics balance the packet delay across ONUs assigned to different groups and Proportional Wavelength Usage (PWU) heuristic reduces power consumption by allocating fewer wavelength resources.

A midterm DBA algorithm for quality of service on aggregation layer EPON networks

This work presents a new approach on dynamic bandwidth allocation (DBA) for Ethernet Passive Optical Networks (EPONs). A brief introduction to the DBA area and major term definitions are given. The related research and standardization efforts are presented. Justification that EPONs can be used on the aggregation network is provided, based on their evolution and related research proposals. Focus is given to the Long Reach-Passive Optical Networks (LR-PONs) and their limitations which show the need for a non-polling, midterm DBA scheme for next-generation EPONs. The challenges arising, because of this new approach, are discussed along with possible solutions. Finally, this work proposes the EMDBA algorithm which is able to overcome the discussed issues. The correct operation of this algorithm is confirmed by a set of simulations using OMNet++ framework, and the outcome results show that EMDBA performance is satisfactory in terms of delay and service differentiation.

A Comparative Study of Dynamic Bandwidth Allocation Algorithms for long Reach Passive Optical Networks

Passive Optical Networks (PON) have emerged as an important fiber-based access network alternative to DSL, Cable, and other access networks. Some of the limitations of PONs are that it can support only up to 64 subscribers and reach up to 20 km. Dynamic Bandwidth Allocation (DBA) algorithms enable multiple subscriber nodes to efficiently share the upstream channel. In this paper, we investigate the performance of DBA algorithms for Long Reach passive optical networks (LR-PON) that support network coverage up to 200 km and up to 2 048 subscribers. Thus, LR-PONs can act as integrated metropolitan and access networks. Due to the increase in round trip time of the network from a few hundred ms in case of PON to few milliseconds in case of LR-PON, DBA algorithms proposed for PONs may not be applicable as is to LR-PONs. The algorithms studied are WDM-IPACT, Intelligent Gap Filling strategy, Multi- thread Polling, and Newly Arrived Frames Plus. The algorithms have been compared in terms of packet delay and consumed CPU resources, using discrete-event simulation modeling. The results indicate that Multi-Thread Polling is most efficient in terms of packet delay; however, WDM-IPACT leads to 20% increased delay while consuming only 50% of the CPU resources required for Multi-thread Polling.