An efficient reservation MAC protocol with preallocation for high-speed WDM passive optical networks
ABSTRACT Wavelength division multiplexing passive optical networks (WDM PONs) can dynamically offer each end user a unique optical wavelength for data transmission as well as the possibility of wavelength reuse and aggregation, thereby ensuring scalability in bandwidth assignment. In this paper, we propose a new byte size clock (BSC) reservation MAC scheme that not only arbitrates upstream transmission and prevents optical collisions, but also varies bandwidth according to demand and priority, reduces request delay using pre-allocation and delta compression, and handles the addition/reconfiguration of network nodes efficiently. The new access scheme exploits both WDM and TDM to cater for both light and heavy bandwidth requirements and supports both Ethernet and ATM packets without segmenting or aggregating them. Our proposed protocol is not only backward compatible with APON and EPON, but also provides a better utilization of the access link in terms of the throughput and delay. In addition, the amount of pre-allocated bandwidth can be minimized using delta compression, which in turns reduces the latency due to the request and grant mechanism. We analyzed, evaluated, and simulated the performance and practicality of the proposed scheme.
- SourceAvailable from: Gerard Parr
- "The proposed model includes one module for OLT which is part of equipment for the service provider and located in central office, one module for 1: N splitter / combiner which is allocated between OLT and ONU in EPON's TDM access scheme as well as one module for ONU which is placed near or inside customer premises equipment and connects home and business subscribers to the OLT. We implemented our model based on PON physical characteristics and IEEE 802.3ah  standards. The implemented environment and its related components have been fully detailed in following sections. "
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- "Initial EPON designs considered a single wavelength channel for downstream transmission from the optical line terminal (OLT) to the optical network units (ONUs) and a single channel for the upstream ONU-to-OLT transmissions; see, e.g.,            . However, growing bandwidth demand increasingly motivates research on designs with multiple wavelength channels in each direction using wavelength division multiplexing (WDM); see, for instance ,         . We consider a WDM EPON architecture where each ONU can receive and transmit on any channel, as described in more detail in Subsection II.A. "
ABSTRACT: The fundamental stability limit and packet delay characteristics of offline scheduling, an elementary scheduling mechanism in recently proposed dynamic bandwidth allocation mechanisms for Ethernet passive optical networks (EPONs) with wavelength division multiplexing (WDM), are unknown. For Poisson packet traffic and gated grant sizing, we develop an analytical framework for characterizing the stability limit and packet delay of off-line scheduling in WDM EPONs. We consider two reporting strategies: immediate reporting, whereby the report is immediately attached to an upstream data transmission, and synchronized reporting, where all reports are sent at the end of a polling cycle. We find that our analytical framework correctly characterizes the stability limit and approximates the delay of (i) synchronized reporting with arbitrary traffic loading and (ii) immediate reporting with symmetric traffic loading (where the number of equally loaded ONUs is an integer multiple of the number of upstream channels). For immediate reporting with asymmetric traffic loading, we discover and analytically characterize multicycle upstream transmission patterns that may increase or decrease the stability limit from the limit for synchronized reporting. We complement the analysis and simulation for Poisson packet traffic with simulations for self-similar packet traffic and observe that self-similar traffic results in substantially higher delays at low to medium loads as well as slightly higher stability limits than Poisson traffic.Journal of Optical Communications and Networking 02/2010; DOI:10.1364/JOCN.2.000051 · 1.55 Impact Factor
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- "Furthermore, they applied strict priority scheduling to support QoS in WDM-PON. A byte-size clock (BSC) protocol  with QoS support that allocates wavelengths on a user-basis rather than ONU-basis is proposed. The approach is scalable in bandwidth assignment and achieves reduction in packet delays; however, in BSC, all nodes need to be synchronized and, as a result, the TDM frame does not comply with IEEE 802.3ah. "
ABSTRACT: We discuss a wavelength-division-multiplexed-based passive-optical-network (PON) architecture that allows for incremental upgrade from single-channel time-division multiple-access PONs in order to provide higher bandwidth in the access network. Various dynamic-wavelength and bandwidth-allocation algorithms (DWBAs) for wave-division multiplexed PON are presented; they exploit both interchannel and intrachannel statistical multiplexing in order to achieve better performance, especially when the load on various channels is not symmetric. Three variants of the DWBA are presented, and their performance is compared. While the first variant incurs larger idle times (and, hence, poor performance), the other two algorithms achieve better but different performance with critical dissimilarities. Our analysis also focuses on the fair assignment of excessive bandwidth in the upstream direction to highly loaded optical network units. We compare the performance of DWBA to another algorithm that relies on static-channel allocation. Furthermore, a study is presented wherein the number of wavelengths increases, and a comparison with interleaved polling with adaptive cycle time is shown. We use extensive simulations throughout this paperJournal of Lightwave Technology 02/2007; 25(1):277-286. DOI:10.1109/JLT.2006.886683 · 2.86 Impact Factor