In this paper, we introduce a new dynamic bandwidth allocation (DBA) algorithm for long-reach passive optical networks (LR-PON) based on the multi-threads (MT) polling algorithm. For the proposed new DBA algorithm, named as the Adaptive Multi-GAte polling with Void filling (AMGAV), the number of threads changes according to the traffic load of a PON in contrast to the static number of threads used in the MT polling algorithm. This makes the algorithm adaptive to load variations and it improves the delay performance for both higher and lower load scenarios. Moreover, the AMGAV algorithm requires no extra effort to enforce separation between threads which makes it simpler to implement than the MT polling algorithm. In the process, we also propose a novel bandwidth reporting scheme which does not have to keep track of the number of threads. Finally, through extensive simulations, we prove that for LR-PON, the AMGAV algorithm provides a better delay performance than the MT polling algorithm for a network load up to 90%, and a comparable performance at higher loads while improving the channel utilization. Keywords: Long Reach PON (LR-PON), Void Filling, Multi-threads, Adaptive Multi-Gate Polling. With the advances in optical technology, the reach of passive optical networks (PONs) has increased from 20 km to 100 km or more. A PON with an increased reach is referred to as SuperPON or Long-Reach PON (LR-PON) in the literature [1] . There are various reasons to investigate LR-PON. The LR-PON can simplify the network by minimizing the number of equipment interfaces, network elements and nodes. Also, it is worth to increase the network span to cover more users to make full use of the increased optical capacity delivered by higher line rates (e.g., 10 Gbps) in the time-division multiplexing (TDM) domain and/or the usage of wavelength-division multiplexing (WDM) technology. We propose a TDM based dynamic bandwidth allocation (DBA) algorithm which can be used in LR-PON using either a TDM PON or a hybrid WDM/TDM PON technology [2] . In TDM PON, several DBA algorithms have been proposed of which IPACT is the most important example for Ethernet PON (EPON) [3] . In traditional TDM PON DBA algorithms, a new communication (thread) between an optical line terminal (OLT) in the central office and an optical network unit (ONU) at the user end is only started after the completion of the previous one, and these algorithms are referred to as single-thread (ST). The authors in [4] have shown that ST DBA algorithms lead to a degraded performance (i.e. an increase in the average packet delay) in LR-PON because of the large round-trip time (RTT) between an OLT and an ONU. To mitigate this large RTT effect, the authors in [4] have proposed the multi-threads (MT) polling algorithm where many parallel communications (or threads) are started between an OLT and an ONU. In this paper, we propose the Adaptive Multi-GAte polling with Void filling (AMGAV) algorithm to overcome some problems of the current MT polling algorithm. In Section 2, we describe the problems of the MT polling algorithm and give a motivation for the proposal of a new DBA algorithm. In Section 3, we describe the AMGAV algorithm and in Section 4 we discuss the simulation results. Finally, Section 5 concludes the paper.
Dynamic adaption of the number of threads, e.g., according to the traffic load REF , which can reduce delays at the expense of increased complexity, is beyond the scope of this study.
Adaptive Multi-Gate polling with Void filling for long-reach passive optical networks
2011 13th International Conference on Transparent Optical Networks
2011 13th International Conference on Transparent Optical Networks
Computer Science