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

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

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.

With the advances in optical technology, the span of a broadband access network using passive optical network (PON) technology can be increased from today's standard of 20 km to 100 km or higher, and thereby serve a lot more users. Such an extended-reach PON is known as SuperPON in the literature, and we call it a long-reach PON (LR-PON). A major challenge in LR-PON is that the propagation delay (for data as well as signals) between the telecom central office (CO) and the end user is increased by a very significant amount. Now, traditional PON algorithms for scheduling the upstream transmission, such as dynamic bandwidth allocation (DBA) algorithms, may not be sufficient; actually, they may lead to degraded performance because of the long delay of the CO-to- Users control loop. This challenge motivates us to propose and study a multi-thread polling algorithm to effectively and fairly distribute the upstream bandwidth dynamically. This algorithm exploits the benefits of having multiple polling processes running simultaneously and enabling users to send bandwidth requests before receiving acknowledgement from the CO. We compare the proposed algorithm with traditional DBA, and show its advantage on average packet delay. We then analyze and optimize key parameters of the algorithm, such as initiating and tuning multiple threads, inter-thread scheduling, and fairness among users. Numerical results demonstrate the algorithm's advantage to decrease the average packet delay and improve network throughput under varying offered loads.

WDM/TDM (wavelength-division multiplexing/time-division multiplexing) PON (passive optical network) appears to be an attractive solution for the next generation optical access networks. Dynamic bandwidth allocation (DBA) plays a crucial role in efficiently and fairly allocating the bandwidth among all users in WDM/TDM PON. In this paper, two dynamic bandwidth allocation schemes (DBA1 and DBA2) are proposed to eliminate the idle time of polling cycles (i.e. polling interval), improve bandwidth utilization and make full use of bandwidth resources. The two DBA schemes adjust the time slot of sending request information and make fair scheduling among users to achieve the effective utilization of polling interval in WDM/TDM PON. The simulation and theoretical analyses verify that the proposed schemes outperform the conventional DBA scheme. We also make comparisons between the two schemes in terms of bandwidth utilization and average packet delay to further demonstrate the effectiveness of the scheme of DBA2.

Ethernet passive optical networks (EPONs) have emerged as the one of the most promising candidates for next-generation access networks. These new architectures couple low-cost optics with advanced edge electronics to offer vastly improved scalability over competing digital subscriber line and cable modem offerings. This paper proposes several novel architectural enhancements for EPON, which will help increase the viability of optical access over a broader range of subscriber access scenarios. Specifically, this paper proposes a two-stage EPON architecture that allows more end-users to share an optical line terminal link, and enables longer access reach/distances (beyond the usual 25 km distance). In addition, a new dynamic bandwidth allocation (DBA) algorithm is proposed to effectively allocate bandwidths between end users. This DBA algorithm can support differentiated services in a network with heterogeneous traffic. We conduct detailed simulation experiments to study the performance and validate the effectiveness of the proposed architecture and algorithms.

In modern, competitive, and dynamic access networks the underlying bandwidth distribution mechanism has to be capable of understanding user requirements, meeting stringent quality of service (QoS) demands, and satisfying a broad spectrum of user traffic dynamics. Undoubtedly, optical fiber is the dominant transmission medium enabling practical and cost-effective optical infrastructures in the last mile. Passive optical networks (PONs) represent one of the most promising player towards the fiber to the home (FTTH) vision allowing users to experience high quality, demanding multimedia services and applications. The 10-gigabit-capable passive optical network (XG-PON), one of the latest PON standard, incorporates a set of profound conditions a contemporary PON should ensure. Fairness provisioning constitutes one of the most critical features a PON should provide. However, ensuring fairness in an access network with numerous different users, requesting multiple traffic flows in any time, is not a straightforward task. In this work, we focus on the fairness issue by devising an adaptive, efficient, and fair dynamic bandwidth allocation (DBA) scheme called Insistent FAIr STrategy prOcesS (IFAISTOS). IFAISTOS investigates and maintains user traffic profiles. Overloaded users are carefully treated by gaining greater granting windows than other users; however bandwidth monopolization is prevented. Fairness is ensured for all users in terms of traffic load and average delay. A steering, adaptive mechanism records user traffic profiles by changing and defining bandwidth weights proportional to individual traffic needs. Extensive simulation results reveal the efficacy of the proposed DBA in terms of fairness and average packet delay.

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.

Advances in high speed network communications have raised the bar of delivering demanding multimedia and data services through Ethernet passive optical networks (EPONs). At their relatively low cost, EPONs have become an attractive solution to providing essential services like voice, video, and data communications reliably, while at the same time providing expected guarantees of the delivery of those services in terms of defined quality of service measures. A continuous theme throughout EPON research has been the study of efficient dynamic bandwidth allocation (DBA) as a key factor in achieving fairness in distributing bandwidth amongst remote network units. In our research, we investigate another factor and its effect of network performance and service delivery: cycle demand proportionality (CDP). By observing the patterns of demand in the network on an individual network unit basis cycle after cycle, we can deduce load characteristics of some units over others. We can then make decisions about subsequent grant allocations based on this factor and aim to achieve better results in the process. We simulate EPONs under varying loads and incorporate the use of CDP in conjunction with currently used DBA schemes. In this paper we present results of achieving improvements in delay performance under light-load circumstances for the cyclic polling DBA scheme

We consider the problem of dynamic bandwidth allocation (DBA) for Ethernet passive optical networks (EPONs), subject to requirements of fairness, efficiency, and cost. The traffic from the access side is aggregated at ONUs and mapped to different classes of service queues. We employ credit pooling technique, together with weighted-share policy, that enables the OLT to partition the upstream bandwidth among different classes, and to prevent ONUs from monopolizing the bandwidth. We propose a packet scheduling algorithm, referred to as COPS (Class-of-service Oriented Packet Scheduling) that meets our requirements set out above. We compare COPS with a well-known scheduling algorithm which employed a standard priority-based scheduling, and we show that COPS is superior in terms of network utilization and maximum packet delay.

Online game's traffic becomes one of the important traffic over the Internet. In last decade, popularity of the Massively Multiplayer Online Game (MMOG) rapidly increased. Most of MMOG are constructed based on client-server architecture. MMOG needs a network with very low-latency point-to-point in upstream direction and low-latency broadcasted from server to client in downstream direction. In the broad-band access networks, passive optical network (PON) is one of the best solutions to meet the higher bandwidth demands with low-latency. Among PON system Ethernet Passive Optical Network (EPON) due to low cost, simplicity, and provide high bandwidth seems one of the best architecture for the MMOG. In this paper, we introduce a new Optical Network Unit (ONU) architecture and new Dynamic Bandwidth Allocation (DBA) for handling online game's traffic. The proposed ONU is able to classify MMOG game and pass it to new queue instead to send the MMOG traffic to the Best Effort (BE) queue. The DBA can delay MMOG queue for some cycle without effect to the delays. Simulation results depict that our propose architecture can improve the overall QoS in terms of mean packet delay and packet loss.

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.

Ethernet Passive Optical Network (EPON) is one of the most promising technologies for FTTX deployed by service providers at the access network. Dynamic Bandwidth Allocation (DBA) for the upstream traffic can help optimize the network bandwidth utilization. This paper discusses a centralized DBA called as Universal DBA (UDBA) algorithm that supports quality of service (QoS) of the upstream traffic. UDBA algorithm is compared with other DBA algorithm to prove its advantages. It shows that UDBA algorithm improves upon expedited forwarding, assured forwarding and best effort delay on average 62.2%, 36.3%, and 23.1% respectively. The fairness index of UDBA algorithm is improved as high as 5.4%.

The most promising technology in optical data transmission at the access network nowadays is the Ethernet passive optical network (EPON). In this paper, we study the delay performance of an intelligent fuzzy logic based dynamic bandwidth allocation (IFLDBA) algorithm for EPON. We evaluate the performance of EPONs from the simulation perspective, where IFLDBA will be compared with some other well known algorithms in terms of the packet delay and bandwidth utilization. This performance evaluation reveals that the IFLDBA shows significant improvement in terms of the packet delay and bandwidth utilization as compared to other hierarchical dynamic bandwidth allocation algorithms.

Broadband Passive Optical Access Networks

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).