A Comparative Study of Dynamic Bandwidth Allocation Algorithms for long Reach Passive Optical Networks
TL;DR: This paper investigates 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 and indicates that Multi-Thread Polling is most efficient in terms of packet delay.
Abstract: 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 a...
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TL;DR: It is found that online MTP and STP as well as DPP give significantly lower average packet delays than offline MTP.
Abstract: Multi-thread polling (MTP) with offline scheduling and offline excess bandwidth distribution has recently been proposed to overcome the long propagation delay of long-reach passive optical networks (LR-PONs). In this paper, we propose a complementary MTP approach with online scheduling and online excess bandwidth distribution. We evaluate the throughput-delay performance of offline and online MTP against offline and online single-thread polling (STP) with excess bandwidth distribution as well as double-phase polling (DPP) with excess bandwidth distribution. We find that online MTP and STP as well as DPP give significantly lower average packet delays than offline MTP.
74 citations
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TL;DR: It is found that for DBAs with offline sizing and scheduling of ONU upstream transmission grants at the end of a polling cycle, which processes requests from all ONUs, reporting at the beginning gives substantial reductions of mean packet delay at high loads.
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TL;DR: In this article, the impact of report message scheduling (RMS) either at the beginning (i.e., before the pay load data) or the end of an ONU upstream transmission on PON performance is investigated.
Abstract: A wide array of dynamic bandwidth allocation (DBA) mechanisms have recently been proposed for improving bandwidth utilization and reducing idle times and packets delays in passive optical networks (PONs). The DBA evaluation studies commonly assumed that the report message for communicating the bandwidth demands of the distributed optical network units (ONUs) to the central optical line terminal (OLT) is scheduled for the end of an ONU's upstream transmission, after the ONU's payload data transmissions. In this article, we conduct a detailed investigation of the impact of the report message scheduling (RMS), either at the beginning (i.e., before the pay load data) or the end of an ONU upstream transmission on PON performance. We analytically characterize the reduction in channel idle time with reporting at the beginning of an upstream transmission compared to reporting at the end. Our extensive simulation experiments consider both the Ethernet Passive Optical Networking (EPON) standard and the Gigabit PON (GPON) standard. We find that for DBAs with offline sizing and scheduling of ONU upstream transmission grants at the end of a polling cycle, which processes requests from all ONUs, reporting at the beginning gives substantial reductions of mean packet delay at high loads. For high-performing DBAs with online grant sizing and scheduling, which immediately processes individual ONU requests, or interleaving of ONUs groups, both reporting at the beginning or end give essentially the same average packet delays.
17 citations
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TL;DR: The proposed scheme eliminates this shortcoming by allocating excess bandwidth to each traffic class completely at the OLT and the UBW assignment mechanism of EBU is also improved.
Abstract: Dynamic bandwidth assignment (DBA) schemes for long reach PONs face a suffer from higher upstream channel idle time due to long round trip time (RTT) In ITU PONs, the DBA schemes; Immediate allocation with colorless grant (IACG), Efficient bandwidth utilization (EBU) and GPON redundancy eraser algorithm (GREAL) minimize idle time by sending bandwidth grants to the optical network units (ONUs) every downstream frame (DF) EBU further improves IACG by utilizing unused bandwidth (UBW) of other traffic classes Sending the grant results every DF requires optical line terminal (OLT) to remember all previous grants sent to ONU during RTT and subtract them from the received queue reports Since, both IACG and EBU assign the excess bandwidth equally to ONUs Therefore, the OLT is actually not aware of the complete grant to each traffic class and thus do not subtract these completely from receiving reports This leads to wastage of bandwidth and higher US delays due to over granting GREAL resolves this problem by not utilizing the excess bandwidth which also leads to increased US delays The proposed scheme in this study eliminates this shortcoming by allocating excess bandwidth to each traffic class completely at the OLT Moreover, the UBW assignment mechanism of EBU is also improved Simulation results show a 50-85 % reduction in delays of type-2 (T2) and type-3 (T3) traffic classes versus GREAL and IACG and up to 40 % reduction in delays for type-4 (T4) versus EBU
17 citations
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TL;DR: It is found that this combination of clustered and localized routing (CluLoR) gives good throughput-delay performance compared to routing schemes that transmit packets wirelessly through “transit zones” (that do not contain the packet source or destination) following minimum hop-count routing.
Abstract: The integration of passive optical networks (PONs) and wireless mesh networks (WMNs) into Fiber- Wireless (FiWi) networks can lead to effective access networks. Existing routing schemes for FiWi networks consider mainly hop-count and delay metrics over a flat WMN node topology and do not specifically prioritize the local network structure, i.e., the local wireless-optical network gateway. In this study, we explore a simple, yet effective routing algorithm for FiWi networks with a WMN organized into zones operating on different radio channels. We examine the effects of routing the traffic into and out of a zone through one or more cluster heads. We investigate the effectiveness of localized routing that prioritizes transmissions over the local gateway to the optical network and avoids wireless packet transmissions in zones that do not contain the packet source or destination. We find that this combination of clustered and localized routing (CluLoR) gives good throughput-delay performance compared to routing schemes that transmit packets wirelessly through “transit zones” (that do not contain the packet source or destination) following minimum hop-count routing.
6 citations
References
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TL;DR: This work investigates design issues for access networks based on passive optical network technology and proposes an interleaved polling algorithm called IPACT and a scheme for in-band signaling that allows using a single wavelength for both downstream data and control message transmission.
Abstract: We investigate design issues for access networks based on passive optical network technology. A PON based on polling, with data encapsulated in Ethernet frames, possesses many desirable qualities, such as dynamic bandwidth distribution, use of a single downstream and a single upstream wavelength, ability to provision a fractional wavelength capacity to each user, and ease of adding a new user. To support dynamic bandwidth distribution, we propose an interleaved polling algorithm called IPACT. We also suggest a scheme for in-band signaling that allows using a single wavelength for both downstream data and control message transmission. To obtain realistic simulation results, we generated synthetic traffic that exhibits the properties of self-similarity and long-range dependence. We then analyzed the network performance under varying offered loads.
837 citations
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TL;DR: The evolutionary path of access networks is reviewed and the drivers from technology and business perspectives for high bandwidth and low cost are shown, and Dynamic Bandwidth Allocation algorithms that allow to mitigate the effect of the increased control-plane delay in an extended-reach network are investigated.
Abstract: Long-Reach optical access is a promising proposal for future access networks. This technology can enable broadband access for a large number of customers in the access/metro area, while decreasing capital and operational expenditures for the network operator. First, the paper reviews the evolutionary path of access networks and shows the drivers from technology and business perspectives for high bandwidth and low cost. A variety of research challenges in this field is reviewed, from optical components in the physical layer to the control and management issues in the upper layers. We discuss the requisites for optical sources, optical amplifiers, and optical receivers when used in networks with high transmission rate (10 Gbps) and large power attenuation (due to large split, transmission over 100 km and beyond, and propagation), and the key topological structures that allow to guarantee physical protection (tree-and-branch, ring-and-spur). Then, some relevant demonstrations of Long-Reach Optical Access Networks developed worldwide by different research institutes are presented. Finally, Dynamic Bandwidth Allocation (DBA) algorithms that allow to mitigate the effect of the increased control-plane delay in an extended-reach network are investigated.
222 citations
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10 Oct 2011
TL;DR: In this article, the authors provide an in-depth overview of PON technologies and the potential applications that they enable, as well as a comprehensive review of all major PON standards and architecture evolutions.
Abstract: Passive optical network (PON) technologies have become an important broadband access technology as a result of the growing demand for bandwidth-hungry video-on-demand applications. Written by the leading researchers and industry experts in the field, this book provides coherent coverage of networking technologies, fiber optic transmission technologies, as well as the electronics involved in PON system development.Features:* An in-depth overview of PON technologies and the potential applications that they enable* Comprehensive review of all major PON standards and architecture evolutions, as well as their pros and cons* Balanced coverage of recent research findings with economic and engineering considerations* Presents system issues of protocols, performance, management and protection* Extensive references to standards and research materials for further studiesThis book provides an authoritative overview of PON technologies and system requirements and is ideal for engineers and managers in industry, university researchers, and graduate students. *Balances treatment of the optical technologies with systems issues such as protocols, performance, management and protection*Covers latest developments in WDM-PONS, protection switching, dynamic bandwidth allocation*Practical coverage with a chapter on PON applications and deployment*Case studies on implementing PONs
195 citations
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TL;DR: A multi-thread polling algorithm to effectively and fairly distribute the upstream bandwidth dynamically and to decrease the average packet delay and improve network throughput under varying offered loads is proposed and studied.
Abstract: 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 control 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.
153 citations
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30 Nov 2004TL;DR: A new WDM PON system is proposed where multiple wavelength channels are established in both upstream and downstream directions and the MAC applied is based on an adaptive polling mechanism, and can be used as an upgrade solution for PON systems.
Abstract: A variety of passive optical network (PON) systems has been proposed to target the bottleneck problem in the local access. The medium access controls (MACs) of the PON systems are either based on cyclic rotation or polling mechanism. However, these MACs have inherited a potential problem; the cycle time (or polling cycle in the polling MACs) increases linearly as the number of attached ONUs scale up, which can be caused by increasing customer numbers. The longer cycle time means that the ONUs have to wait longer before the next transmission window arrives thus contributing to longer packet delays and poorer QoS. In this paper, a new WDM PON system is proposed where multiple wavelength channels are established in both upstream and downstream directions. The MAC applied is based on an adaptive polling mechanism, and can be used as an upgrade solution for PON systems
86 citations