Two-dimensional priority-based dynamic resource allocation algorithm for QoS in WDM/TDM PON networks

A survey of dynamic bandwidth allocation algorithms for Ethernet Passive Optical 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).

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.

Fiber To The Home (FTTH) is an infrastructure that provides a giant boost to the progress of technology driven applications, such as triple play, along with the required software and equipment for their implementation. It consists of an investment for the years to come that speeds development in more than one technological area and promotes overall growth. Nevertheless in a context of continuous effort for more cost effective and energy saving solutions, the need to invest in a structure that is free from excessive expenditure and at the same time is future-proof has become imperative. Deriving of this need, new technological solutions have begun to emerge and the tool for their financial evaluation could be proven of important value for optical network operators. This paper presents a techno-economic comparison of two different passive FTTH network technologies/architectures. The cases considered in this study are namely: i) metro ring in combination with gigabit passive optical networks (GPON) technology on the access part and ii) a new converged access-metro wavelength division multiplexing / time division multiplexing (WDM/TDM) passive optical network (PON) called: scalable advanced ring-based passive dense access network architecture (SARDANA). This work includes a quantitative modeling of the outside plant cost as well as of the active equipment cost of the two architectures. It is shown that the green solution of the PONs in combination with the expected energy savings guarantees a cost effective solution. Furthermore it is shown that the more elaborate design of the WDM/TDM PON provides a cost reduction of about 15% for densely populated areas and even greater for scarcely ones along with an ensured flexibility.

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 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.

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.

The use of passive optical networks (PONs) enables access rates of multi-Gbit/sec bandwidth and provision of quality of service for high definition multimedia services. In this paper, we consider and analyse a generic multi-priority dynamic bandwidth allocation (DBA) algorithm for TDM PONs serving multimedia traffic in an upstream link. PON traffic is served strictly according to its priority. We consider this DBA algorithm using two approaches: (i) the algorithm assigns a fixed service quantum to each priority service and (ii) different service quanta are assigned to different priority services. The mean message delay is evaluated using a multiqueue processor sharing (MPS) model and an MPS with Heterogeneous Traffic (MPS-HT) model for the two approaches respectively. The MPS model is a classical processor sharing model limited by the critical assumption that there is egalitarian service sharing among all users, which is inefficient for multimedia applications in PONs. We extend the MPS model to a general MPS-HT model that enables the analysis of message delay performance in the case where the service quanta may be different for different services.

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.

In this work we propose and analyze the performance of dynamic bandwidth allocation algorithms for optical passive networks (PON) in GPON standard (Gigabit PON). These algorithms use data from SLA (service level agreement) to manage bandwidth allocation and classify in 4 traffic containers (T-CONT) the traffic generated by 16 ONUs (optical network unit). In the upstream transmission the time division multiplexing (TDM) technique is used to manage the medium access, avoiding collisions. The first proposed algorithm allocates guaranteed bandwidth for the ONUs and distributes the bandwidth not used according to the criteria based on three SLAs. The upstream bit rate is 1.25 Gbps and the algorithm performance is analyzed based on the packets delay variation versus the traffic generated by ONUs. The second proposed algorithm uses weighted traffic. In this, we analyze the delay performance and the required bandwidth for each ONU and how much it is served when the guaranteed and extra bandwidth are changed. Finally, we added in our implementation an interval for the processing of the dynamic bandwidth allocation algorithm (DBA) and response of the hardware related to the interrogation cycle. In the end, we propose a preliminary solution to minimize these delays. The results obtained by means of computational simulation show the versatility of the algorithms.

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

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.

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.

To date, the mainstream ethernet passive optical network (EPON) bandwidth allocation schemes as well as the new IEEE 802.3ah Ethernet in the first mile Task Force specifications have been centralized, relying on a component in the central office [optical line termination (OLT)] to provision upstream traffic. Hence, the OLT is the only device that can arbitrate time-division access to the shared channel. Since the OLT has global knowledge of the state of the entire network, this is a centralized control plane in which the OLT has centralized intelligence. This paper proposes novel distributed EPON architectures, and in the process proves that these distributed networking architectures and the associated bandwidth allocation algorithms and protocols have characteristics that make them far better suited for provisioning quality of service (QoS) schemes necessary for properly handling data, voice, video, and other real-time streaming advanced multimedia services over a single line. Specifically, this paper proposes a novel ethernet over star coupler-based PON architecture that uses a fully distributed time-division multiple-access (TDMA) arbitration scheme. Supported by the decentralized scheme, this paper proposes several QoS-based dynamic bandwidth allocation (DBA) algorithms in which the OLT is excluded from the implementation of the time slot assignment. In contrast with the mainstream centralized EPON architectures that combine priority queuing [intra-optical network unit (ONU) scheduling] with DBA schemes (inter-ONU scheduling), the proposed distributed EPON architecture supports differentiated services through the integration of both scheduling mechanisms at the ONU (intra-ONU scheduling). The introduction of this integration feature that can only be supported by a decentralized architecture provides better QoS guarantees. Furthermore, in addition to the added flexibility and reliability, the overall performance of the proposed decentralized EPON architecture and the associated bandwidth allocation algorithms are shown to be at least as efficient as their centralized counterparts.

Hybrid wavelength division multiplexing/time division multiplexing (WDM/TDM) scheduling in multi-channel Ethernet passive optical networks (EPON) is gaining popularity compared to its only TDM or only WDM counterpart as they provide more flexibility, energy efficient load distribution and increased number of users and bandwidth support. In this paper, we have summarized the existing proposals for multi-channel EPON and proposed a novel scheme to further enhance the scheduling efficiency. For that purpose, a Modified Stable Matching Algorithm (MSMA) has been developed. We have also introduced a predictive just-in-time scheduling framework to dynamically evoke the MSMA in real time. We have provided extensive simulation results to prove the effectiveness of our proposed scheduling scheme compared to other existing schemes.