Performance Analysis of the Limited Bandwidth Allocation Scheme With Excess Distribution

Power budget of direct-detection ultra-dense WDM-Nyquist-SCM PON with low-complexity SSBI mitigation

An ILP-based CapEx and OpEx efficient multi-stage TDM/TWDM PON design methodology

Energy-efficient passive optical networks (PONs) have gained significant interest since they are estimated to be the largest energy consumers among the wired access networks for the next ten years. In Ethernet PONs (EPONs), the equipment placed at the customer premises, i.e., the optical network units (ONUs), has been shown to be responsible for almost 65% of the total EPON power consumption. Sleep mechanisms, implemented at ONUs’ side, can contribute to the EPONs’ energy-efficiency. However, the tradeoff between energy saving and quality of service (QoS) requirements should be carefully tuned, especially when the downstream transmission is considered, to achieve the desirable results. In this paper, we propose a general framework that exploits formal methods as an approach for EPONs’ energy-efficiency. The idea is to build a holistic model representing both the state machine of the ONU in its details as well as the ONU’s communication with the optical line terminal under EPONs’ specifications. Verification results reveal that, guided by the QoS constraints and considering the transitions’ cost, an “aggressive” policy defining long sleep periods of the 100 ms order can be up to 24.9% beneficial for energy-efficiency compared to a “conservative” policy with sleep periods of the 10 ms order.

In this paper the end-to-end TCP performance of a hybrid network composed of multiple Ethernet Passive Optical Networks (EPONs) in the access segment connected to the same edge node of a core network is evaluated. Three possible core network paradigms are considered: Optical Circuit Switching (OCS), Optical Burst Switching (OBS) and Optical Packet Switching (OPS). TCP performance is evaluated through simulations with ns-2. The hybrid network scalability is assessed by varying the number of EPONs connected to the same edge node and the number of Optical Network Units (ONUs) per EPON. Interoperability issues between access and core are investigated and the impact of the most important network parameters is highlighted. The three transfer modes considered for the core network are properly compared under different input conditions, discussing the related trade-offs that may lead to the most suitable choice based on the specific application scenario. Finally, some design issues are investigated with reference to emerging Long-Range EPON (LR-EPON) solutions.

The evolution of the Ethernet passive optical network (EPON) to the enhanced 10G-EPON standard looks poised to maintain its position as the leading fiber to the home technology worldwide. Fair bandwidth allocation will be a challenge in the near future in plants where 1G and 10G customer premises equipment coexists. In this paper we propose a distributed algorithm, distributed dynamic scheduling for EPON (DDSPON), to dynamically allocate the bandwidth requested by the user equipment with quality of service (QoS) constraints. The proposed algorithm is scalable and simple to re-configure, which facilitates a smoother transition from legacy 1G to 10G networks. By using the DDSPON, enhanced optical network units (ONUs) will take full advantage of the 10 Gb/s rate while legacy 1G ONUs maintain their service level agreement; as a result, the individual performance is maximized for both groups of ONUs. We also present an analytical model to evaluate the algorithm performance in a coexistent 1G/10G network. Finally, we also illustrate the enhancement of the DDSPON to provision the QoS to different services under the DiffServ architecture. Analysis and simulation results validate the effectiveness of the proposed mechanisms.

We address the QoS (Quality of Services) bandwidth reservation and service work scheduling mechanism of how to fairly provide advance quality of service in polling based TDM networks like Ethernet PON (Passive Optical Networks). Unlike existing differentiated QoS supporting schemes, such as SP (Strict Priority) based DBA (Dynamic Bandwidth Allocation) or static work scheduling with min-max theory, proposed service quality pre-engagement (SQP) for prioritized packet scheduling and equal weighted fair bandwidth arbitration (EWF-BA) for fair services among access nodes reflect the dynamically changing service pattern of access node like ONU (Optical Network Unit). The performance results show that the service fairness and QoS are tightly coupled and proposed mechanisms achieve better QoS performances with high fairness and better network performances both in Poisson and Self-similar traffic environment.KeywordsQueue SizeOptical Network UnitAccess NodePassive Optical NetworkDynamic Bandwidth AllocationThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Traffic localization-based dynamic bandwidth allocation algorithm for improvement of QoS in peer-to-peer architecture of passive optical networks

Wavelength division multiplexing/time division multiplexing (WDM/TDM) passive optical networks (PON) is being viewed as a promising solution for delivering multiple services and applications. The hybrid WDM / TDM PON uses the wavelength and bandwidth allocation strategy to control the distribution of the wavelength channels in the uplink direction, so that it can ensure the high bandwidth requirements of multiple Optical Network Units (ONUs) while improving the wavelength resource utilization. Through the investigation of the presented dynamic bandwidth allocation algorithms, these algorithms can't satisfy the requirements of different levels of service very well while adapting to the structural characteristics of mixed WDM / TDM PON system. This paper introduces a novel wavelength and bandwidth allocation algorithm to efficiently utilize the bandwidth and support QoS (Quality of Service) guarantees in WDM/TDM PON. Two priority based polling subcycles are introduced in order to increase system efficiency and improve system performance. The fixed priority polling subcycle and dynamic priority polling subcycle follow different principles to implement wavelength and bandwidth allocation according to the priority of different levels of service. A simulation was conducted to study the performance of the priority based polling in dynamic resource allocation algorithm in WDM/TDM PON. The results show that the performance of delay-sensitive services is greatly improved without degrading QoS guarantees for other services. Compared with the traditional dynamic bandwidth allocation algorithms, this algorithm can meet bandwidth needs of different priority traffic class, achieve low loss rate performance, and ensure real-time of high priority traffic class in terms of overall traffic on the network.

An Ethernet passive optical network (EPON) is an optical access network that allows a higher data rate with low power consumption. To improve energy savings for an EPON, the sleep and doze modes for the optical network units (ONUs) play a pivotal role. Many prediction schemes have been proposed to control these modes. To increase the prediction accuracy, this study proposes an energy-efficient approach that uses a support vector regression (SVR) model. A dynamic bandwidth allocation (DBA) scheme called SVR-DBA is designed to allocate bandwidth to ONUs more efficiently and fairly. To determine the effectiveness of the proposed scheme, simulations are performed. The simulation results show that the proposed scheme decreases energy consumption for ONUs by up to 47% and fulfills the quality-of-service (QoS) requirements in terms of delay, jitter, and packet loss.

This paper describes a novel channel allocation and DBA (Dynamic Bandwidth Allocation) mechanism for ECDM-PON (Electric Code Division Multiplex — Passive Optical Network) systems. In the current ECDM-PON systems, each ONU (Optical Network Unit) is limited to 2 or 3 CDM channels. This is because (fixed channel) CDM transmitters are expensive, and tunable CDM transmitters even more expensive. With a small number of CDM channels, the bandwidth utilization ratio is restricted by channel blocking. Our proposed mechanisms can reduce the channel blocking ratio without increasing the number of CDM transmitters or using tunable CDM transmitters. To clarify the advantages of the proposed system performance, we have evaluated the channel non-blocking ratio (Rn) and wasted resource ratio (Rw) when some users request bandwidth more than 100%. Evaluation of the non-blocking ratio, Rn shows that the proposed mechanisms approach the performance of a system with tunable CDM transmitters when the number of ONUs with over 100% traffic load is small. We have also simulated throughput for uniform traffic. In addition to these evaluations, we implemented our proposed mechanism on an FPGA (Field Programming Gate Array) and evaluated the calculation speed to allocate timeslots on CDM channels and a timeline.

Adopting the pay-as-you-grow approach to upgrade passive optical network (PON) facilities by WDM technology insures the smoothness of the upgrade, and also results in the coexistence of wavelength-fixed/tunable optical network units (ONUs) in WDM/TDM PONs. Dynamic bandwidth allocation (DBA) is the key to support such coexistence of heterogeneous ONUs. Thus, DBA is also the key to support the smooth evolution of PONs. To more fairly coordinate the bandwidth allocation among the coexisting heterogeneous ONUs, a differentiated grant sizing (DGS) scheme is proposed. In DGS, not only the fairness between the wavelength-fixed/tunable ONUs but also the fairness between the lightly/heavily loaded ONUs is taken into account. To further carry out load balancing among wavelengths, a grant scheduling scheme is also proposed to cooperate with the grant sizing scheme. In the grant scheduling scheme, a measure of the ONUs’ flexibility is given, and then the least flexible job first rule (LFJF) is adopted for joint wavelength and time-slot assignment. Finally, to demonstrate the effectiveness of the proposed algorithm, a series of comparative analyses is conducted based on simulation experiments.

Passive optical networks (PONs) are thought to be the next step in the development of access networks and providing broadband access in the ¿last mile¿ area. Ethernet PON (EPON) gains the most attention from the researchers as it offers highly flexible and cost effective solution. In this paper we propose two high level scheduler algorithms inside the optical line terminal (OLT) and optical network units (ONU). In the proposed dynamic bandwidth allocation (DBA) algorithm, the OLT allocates the bandwidth to the ONUs in proportion to the weight associated with the excess bandwidth available, while the ONU preferentially allocates its bandwidth to queues with a strict or non strict priority order. The algorithms provide dynamic bandwidth allocation and separate the burden of queue management fairly between the customer and the network. This led to less complicated and more intelligent equipment has been used on the customer's premises. We show the results of simulations to validate the effectiveness of algorithms presented and to provide quality of service (QoS) for triple play real time services in Ethernet passive optical networks (EPONs).

The potential for sharing infrastructure costs between a large number of customers and the high data rates allowed by optical fibres make passive optical networks (PONs) an attractive solution to the problem of upgrading current copper-based access networks. Optically-amplified, long reach, time division multiple access (TDMA) PONs or 'SuperPONs' offer the potential to further reduce bandwidth transport costs by enabling the direct connection of access networks and inner core networks, thereby eliminating the costs of the outer core/metro backhaul network. The use of dense wavelength division multiplexing (DWDM) could also allow sharing the same feeder fibre and PON head end equipment between a number of such TDMA SuperPONs, each working at different ITU-grid wavelengths. However, a cost effective access solution should employ a customer optical network unit (ONU), which is independent of the PON wavelength, or colorless, in order to reduce the high inventory and deployment costs of using expensive, wavelength-specified sources at the customer. In this paper we demonstrate for the first time the use of a monolithically-integrated, electroabsorption modulator-semiconductor optical amplifiers (EAM-SOAs) as a colorless ONU in a high performance DWDM SuperPON system. These compact devices offer the potential for low-cost optoelectronic integration with other ONU components together with the ability to modulate at rates up to 10Gbps and beyond. We have used this approach to investigate the feasibility of supporting up to 17 SuperPONs from a single feeder fibre and PON head end, each of 100km-reach accommodating 512 users at 2.5Gb/s or 128 at 10Gb/s.

We investigate FTTX (Fiber-to-the Home/Premises/Curb) Passive Optical Networks (PON) for the deployment of broadband access networks such that the opportunities of optical fiber enabled technologies as well as of passive switching equipment can be exploited. We focus on designing the best possible architectures of hybrid FTTX PONs, which embraces both TDM and WDM technology. Advantages of hybrid PONs are twofold: they can (i) offer increased data rate to each user by employing WDM technology, (ii) provide flexible bandwidth utilization by employing TDM technology. We propose a novel network design optimization scheme for greenfield deployment of a set of hybrid PONs. For a given geographical location of an optical line terminal (OLT), a set of optical network units (ONUs) and their corresponding aggregated traffic demand, our proposed optimization scheme determines the design and dimensioning of the most economical set of hybrid PON networks while satisfying unicast/multicast traffic demands and taking into account the signal attenuation constraints. Computational experiments have been conducted on a set of up to 512 ONUs in order to evaluate the performance of the proposed scheme.

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.