Dynamic Bandwidth Allocation in Heterogeneous OFDMA-PONs Featuring Intelligent LTE-A Traffic Queuing

This work was supported by the ACCORDANCE project, through the 7th ICT Framework Programme. This is an Accepted Manuscript of an article accepted for publication in Journal of Lightwave Technology following peer review. © 2014 IEEE Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.A heterogeneous, optical/wireless dynamic bandwidth allocation framework is presented, exhibiting intelligent traffic queuing for practically controlling the quality-of-service (QoS) of mobile traffic, backhauled via orthogonal frequency division multiple access–PON (OFDMA-PON) networks. A converged data link layer is presented between long term evolution-advanced (LTE-A) and next-generation passive optical network (NGPON) topologies, extending beyond NGPON2. This is achieved by incorporating in a new protocol design, consistent mapping of LTE-A QCIs and OFDMA-PON queues. Novel inter-ONU algorithms have been developed, based on the distribution of weights to allocate subcarriers to both enhanced node B/optical network units (eNB/ONUs) and residential ONUs, sharing the same infrastructure. A weighted, intra-ONU scheduling mechanism is also introduced to control further the QoS across the network load. The inter and intra-ONU algorithms are both dynamic and adaptive, providing customized solutions to bandwidth allocation for different priority queues at different network traffic loads exhibiting practical fairness in bandwidth distribution. Therefore, middle and low priority packets are not unjustifiably deprived in favor of high priority packets at low network traffic loads. Still the protocol adaptability allows the high priority queues to automatically over perform when the traffic load has increased and the available bandwidth needs to be rationally redistributed. Computer simulations have confirmed that following the application of adaptive weights the fairness index of the new scheme (representing the achieved throughput for each queue), has improved across the traffic load to above 0.9. Packet delay reduction of more than 40ms has been recorded as a result for the low priority queues, while high priories still achieve sufficiently low packet delays in the range of 20 to 30msPeer reviewe

MAC Protocol Design for the Support of DBA in OFDMA-PON Networks

Wansu Lim, Ali Gliwan, Pandelis Kourtessis, Konstantinos Kanonakis, Ioannis Tomkos, John Senior, 'MAC Protocol Design for the Support of DBA in OFDMA-PON Networks', Paper presented at the Future Network and Mobile Summit, 15-17 June 2011, Warsaw, Poland.Original MAC frame formats have been developed to provide recommendations for new protocol designs in OFDMA-PONs. The portrayed scalability of the Dynamic Subcarrier Allocation (DScA) protocol is complemented by the granularity of hybrid OFDMA/TDMA topologies. Modelling of the DScA performance in OPNET has recorded the maximum 312.5 Mbits/s transmission rate capacity per ONU achieved at less than 2 ms packet delay and more than 95% network throughput depending on ONU offered load.Peer reviewe

Architectures and protocols of optical networks with emphasis on optical burst switched WDM networks

The main goal of this thesis is the proposal of a novel WDM optical core network architecture, as well as of the accompanying protocols. This novel approach offers solutions to the problems of existing proposals in this field. More specifically, optical burst-switched networks, though designed for compromising the increasing burstiness of traffic with available optical technology, show extremely high loss rates even at extremely low network loads, as well as a high degree of complexity and cost. The proposed approach is an efficient and viable solution. The main idea is to exploit the already available electronic buffers at the edge nodes of the optical network and the acceptance of a controlled increaser of delay. Using the concept of slotting, pipelined two-way reservations and a clever scheduling mechanism, this system eliminates loss (except from the loss due to buffer overflows) and at the same time guarantees features that favor quality of service. The various aspects of the proposed system are analyzed in depth and its increased efficiency is proved using computer simulation as well as analytical modeling. Since the aforementioned proposal is applies to limited areas, another architecture is also proposed that implements distributed, all-optical switching of payload by dividing the core network into a number of limited size clusters, inside which traditional two-way reservation schemes become meaningful. Thus, inside such a cluster loss is eliminated, while traffic from many nodes can be assembled into bursts, increasing network efficiency. The lossless aggregation of traffic from many core nodes allows the application of bufferless transmission between clusters, combined with the use of electronic buffering at the network periphery. The end result is a triple improvement in burst loss, efficiency and cost. Finally, another goal of the thesis is the proposal of a novel traffic aggregation technique for optical burst-switched core networks, as well as its analytical modeling. Such mechanisms are critical for the efficient operation of core networks, since they affect critical parameters, such as delay and network resource utilization. The proposed method manages to guarantee the quality of service of demanding traffic while keeping the utilization at high levels.Ο κυριότερος στόχος της διατριβής είναι η πρόταση μίας καινοτόμας αρχιτεκτονικής οπτικών δικτύων κορμού WDM μεταγωγής ριπών, καθώς και των πρωτοκόλλων που τη συνοδεύουν. Η νέα αυτή προσέγγιση έρχεται να δώσει λύσεις στα προβλήματα που εμφανίζουν οι ήδη υπάρχουσες προτάσεις στον τομέα αυτό. Πιο συγκεκριμένα, τα οπτικά δίκτυα κορμού μεταγωγής ριπών, αν και είναι σχεδιασμένα για να συμβιβάσουν την αυξανόμενη εκρηκτικότητα της κίνησης με τη διαθέσιμη οπτική τεχνολογία, παρουσιάζουν πολύ υψηλά ποσοστά απωλειών ακόμα και σε πολύ χαμηλά φορτία δικτύου, καθώς και υψηλό βαθμό πολυπλοκότητας και κόστους. Η προτεινόμενη προσέγγιση αποτελεί μία εξαιρετικά αποδοτική και εφαρμόσιμη λύση. Η βασική ιδέα έγκειται στην εκμετάλλευση της διαθέσιμής ηλεκτρονικής ενταμίευσης στους ακραίους κόμβους του οπτικού δικτύου και η αποδοχή μίας ελεγχόμενης αύξησης στην καθυστέρηση. Χρησιμοποιώντας την έννοια των χρονοσχισμών και κάνοντας χρήση παραλληλισμένων διμερών δεσμεύσεων και ενός έξυπνου μηχανισμού χρονοδρομολόγησης, το σύστημα αυτό καταργεί τις απώλειες (εκτός από αυτές που οφείλονται σε υπερχείλιση των ακραίων ηλεκτρονικών ενταμιευτών), αλλά ταυτόχρονα εξασφαλίζει χαρακτηριστικά που ευνοούν την ποιότητα των υπηρεσιών. Οι διάφορες πτυχές του προτεινόμενου συστήματος αναλύονται σε βάθος και η βελτιωμένη απόδοσή του αποδεικνύεται με τη βοήθεια προσομοιώσεων σε υπολογιστή, αλλά και με τη χρήση μαθηματικής μοντελοποίησης. Καθώς η προαναφερθείσα πρόταση αναφέρεται σε δίκτυα περιορισμένης χωρικής έκτασης, προτείνεται επιπλέον και μία αρχιτεκτονική η οποία υλοποιεί κατανεμημένη, αμιγώς οπτική μεταγωγή του φορτίου, διαιρώντας το δίκτυο κορμού σε ένα πλήθος περιφερειών ή ομάδων περιορισμένης γεωγραφικής έκτασης, μέσα στις οποίες παραδοσιακά σχήματα διμερούς δέσμευσης πόρων, αποκτούν νόημα. Έτσι, μέσα σε κάθε τέτοια ομάδα οι απώλειες εξαλείφονται, ενώ κίνηση από πολλούς κόμβους μπορεί να συσσωματωθεί σε ριπές, βελτιώνοντας την απόδοση του δικτύου. Η χωρίς απώλειες συγκέντρωση της κίνησης από αρκετούς κόμβους κορμού επιτρέπει τη χρήση συμφέρουσας μεταφοράς χωρίς ενταμίευση μεταξύ των περιφερειών, σε συνδυασμό με τη χρήση ηλεκτρονικής ενταμίευσης στην περιφέρεια του συστήματος. Το τελικό αποτέλεσμα είναι μία τριπλή βελτίωση, στις πιθανότητες απωλειών, στην απόδοση και στο κόστος. Τέλος, ένας ακόμα στόχος της διατριβής είναι η πρόταση μίας νέας τεχνικής για συγκέντρωση κίνησης σε οπτικά δίκτυα κορμού μεταγωγής ριπών καθώς και η αναλυτική μοντελοποίηση αυτής. Η σημασία των μηχανισμών αυτών είναι γενικά ζωτική για την αποδοτική λειτουργία των δικτύων κορμού, καθώς επηρεάζουν σημαντικές παραμέτρους, όπως η καθυστέρηση και η χρησιμοποίηση των πόρων του δικτύου. Η προτεινόμενη μέθοδος καταφέρνει να εξασφαλίζει την ποιότητα υπηρεσίας απαιτητικών μορφών κίνησης, διατηρώντας παράλληλα τη χρησιμοποίηση σε υψηλά επίπεδα

Flexible QoS Differentiation in Converged OFDMA-PON and LTE Networks

We propose a Weighted-DSA scheduling algorithm which allows efficient mapping of LTE QCIs over the optical queues of an OFDMA-PON. A 63ms end-end wireless packet delay has been demonstrated for QCI5 at highest network load

An OFDMA-Based Optical Access Network Architecture Exhibiting Ultra-High Capacity and Wireline-Wireless Convergence

This paper presents a novel optical access network architecture based on Orthogonal Frequency Division Multiple Access (OFDMA) technology and applied on a Passive Optical Network (PON) topology. In compliance with Next Generation Optical Access (NGOA) requirements, this architecture targets to outperform existing PON solutions in terms of total capacity, bandwidth allocation flexibility, number of users and network reach. Moreover, it provides the opportunity for convergence with wireless technologies and a smooth migration path from legacy access solutions like TDMA-PONs and DSL.Peer reviewedSubmitted Versio

Modeling of LTE back-hauling through OFDMA-PONs

This paper evaluates a novel mapping and scheduling scheme which allows efficient control over the quality-of-service (QoS) experienced by long term evolution (LTE) users when backhauled over an orthogonal frequency division multiple access-passive optical network (OFDMA-PON). With respect to mapping, the LTE QoS class identifiers (QCIs) are assigned to the OFDMA-PON priorities based on class-of-service (CoS) differentiation. Scheduling involves the allocation of subcarriers to each optical network unit/enhanced node B (eNB/ONU) ensuring that the bandwidth allocation accounts for the QoS requirements of the respective LTE wireless bearers. Since the transmission pipes allocated to each eNB/ONU are to be shared by all CoS queues, fairness across traffic priorities throughout the network is achieved by introducing a weighted dynamic subcarrier assignment (WDSA) algorithm. Simulations are based on a 10Gbps OFDMA-PON with 1024 subcarriers, 20km reach and 32 eNB/ONUs. Performance evaluation figures confirm that the end-end wireless packet delay and queue lengths of the high priority queues benefit significantly from the application of the WDSA algorithm without failing the rest of the network performanc