Unbundling in Current Broadband and Next-Generation Ultra-Broadband Access Networks

This article overviews the methods that are currently under investigation for implementing multi-operator open-access/shared-access techniques in next-generation access ultra-broadband architectures, starting from the traditional "unbundling-of-the-local-loop" techniques implemented in legacy twisted-pair digital subscriber line access networks. A straightforward replication of these copper-based unbundling-of-the-local-loop techniques is usually not feasible on next-generation access networks, including fiber-to-the-home point-to-multipoint passive optical networks. To investigate this issue, the article first gives a concise description of traditional copper-based unbundling-of-the-local-loop solutions, then focalizes on both next-generation access hybrid fiber-copper digital subscriber line fiber-to-the-cabinet scenarios and on fiber to the home by accounting for the mix of regulatory and technological reasons driving the next-generation access migration path, focusing mostly on the European situation. © 2014 Taylor and Francis Group, LLC

Εισαγωγή της Τεχνολογίας Vectoring στην Ελλάδα: Τεχνολογική και Ρυθμιστική προσέγγιση

Το Ψηφιακό Θεματολόγιο για την Ευρώπη (Digital Agenda for Europe) έχει θέσει ως στόχο έως το 2020 κάθε Ευρωπαίος πολίτης να έχει πρόσβαση στο διαδίκτυο με ταχύτητα άνω των 30 Mbps και τουλάχιστον το 50% των ευρωπαϊκών νοικοκυριών να είναι συνδεδεμένο με τα ταχύτητες 100 Mbps και άνω. Σε αυτή την κατεύθυνση, οι ελληνικοί τηλεπικοινωνιακοί πάροχοι εκκίνησαν κύκλο επενδύσεων με σκοπό την αναβάθμιση του Δικτύου Πρόσβασης και την παροχή υπηρεσιών πρόσβασης επόμενης γενιάς. Η τεχνολογία Vectoring αποτελεί την κυρίαρχη επενδυτική επιλογή των παρόχων, Η τεχνολογία Vectoring απαιτεί υποδομές FFTCabinet ενώ παράλληλα αξιοποιεί μέρους του υφιστάμενου δικτύου χαλκού και προσφέρει ταχύτητες έως και 100 Mpbs ή 300 Mbps για την τεχνολογία Super Vectoring. Η τεχνική επίτευξης αυτών των ταχυτήτων βασίζεται στην real-time εξουδετέρωση των ηλεκτρομαγνητικών παρεμβολών που δέχεται κάθε ζεύγος χαλκού από τα γειτονικά του ζεύγη (crosstalk). Κάτι τέτοιο προαπαιτεί το σύστημα vectoring να ελέγχει το σύνολο των γραμμών VDSL2 που αλληλεπιδρούν, επιτρέποντας σε κάθε τοπικό κατανεμητή μικρονόμησης να υπάρχει αποκλειστικά ένας Πάροχος υπηρεσίας Vectoring και VDSL2, δημιουργώντας έτσι την αναγκαιότητα ενός νέου ρυθμιστικού πλαισίου. Αντικείμενο της παρούσης εργασίας αποτελεί η τεχνική ανάλυση της τεχνολογίας Vectoring καθώς και η διερεύνηση των κανονιστικών επιλογών της Εθνικής Επιτροπή Τηλεπικοινωνιών και Ταχυδρομείων για την εισαγωγή της τεχνολογίας Vectoring στο ελληνικό δίκτυο πρόσβασης.In the framework of the Digital Agenda for Europe (DAE), by the end of 2020, all European citizens must have an Internet access with bitrate higher than 30 Mbps, and the 50% of European household must have an active Internet connection with bitrate 100 Mbps at least. Corresponding to these targets, greek Internet Service Providers begin to invest in order to upgrade their fixed access network for provision of next generation broadband service. Vectoring makes up the main technological choice to achieve their target. FTTCabinet is the required infrastructure for the Vectoring employment, whereas the traditional copper access network extends its lifespan. The Vectoring technology provides access to the Internet with bitrate up to 100 Mbps and the Super Vectoring up to 300 Mbps. The basic concept of Vectoring technology is a real-time cancelation of FEXT crosstalk. In order to real-time cancelation be achieved, all VDSL2 lines (vectored and non-vectored) of a given Local Distribution Frame have to be controlled by a common Vectoring system. In this way, a single ISP should employ its Vectoring or VDSL system at this network point, creating the need of a new regulatory framework. The scope of this dissertation project is to analyze the technical specification of Vectoring and to investigate the policy that greek National Regulatory Author (EETT) applies for vectoring deployment at the greek access network

Mitigation of impulsive noise for SISO and MIMO G.fast system

To address the demand for high bandwidth data transmission over telephone transmission lines, International Telecommunication Union (ITU) has recently completed the fourth generation broadband (4GBB) copper access network technology, known as G.fast. Throughout this thesis, extensively investigates the wired broadband G.fast coding system and the novel impulsive noise reduction technique has been proposed to improve the performance of wired communications network in three different scenarios: single-line Discrete Multiple Tone (DMT)- G.fast system; a multiple input multiple-output (MIMO) DMTG.fast system, and MIMO G.fast system with different crosstalk cancellation methods. For each of these scenarios, however, Impulsive Noise (IN) is considered as the main limiting factor of performance system. In order to improve the performance of such systems, which use higher order QAM constellation such as G.fast system, this thesis examines the performance of DMT G.fast system over copper channel for six different higher signal constellations of M = 32, 128, 512, 2048, 8192 and 32768 in presence of IN modelled as the Middleton Class A (MCA) noise source. In contrast to existing work, this thesis presents and derives a novel equation of Optimal Threshold (OT) to improve the IN frequency domain mitigation methods applied to the G.fast standard over copper channel with higher QAM signal constellations. The second scenario, Multi-Line Copper Wire (MLCW) G.fast is adopted utilizing the proposed MLCW Chen model and is compared to a single line G-fast system by a comparative analysis in terms of Bit-Error-Rate(BER) performance of implementation of MLCW-DMT G.fast system. The third scenario, linear and non-linear crosstalk crosstalk interference cancellation methods are applied to MLCW G.fas and compared by a comparative analysis in terms of BER performance and the complexity of implementation.University of Technology for choosing me for their PhD scholarship and The Higher Committee For Education Development in Iraq(HCED

Enhanced multi-user DMT spectrum management using polynomial matrix decomposition techniques

This thesis researches the increasingly critical roles played by intelligent resource management and interference mitigation algorithms in present-day input multiple output (MIMO) communication systems. This thesis considers the application of polynomial matrix decomposition (PMD) algorithms, an emerging broadband factorisation technology for broadband MIMO access networks. Present DSL systems’ performance is constrained by the presence of interference (crosstalk) between multiple users sharing a common physical cable bundle. Compared to the traditional static spectrum management methods that define their survival to the worst-case scenarios, DSM methods provides some degree of flexibility to both direct channel and noise parameters to improve evolvability and robustness significantly. A novel crosstalk-aware DSM algorithm is proposed for the efficient management of multi-user DSL systems. Joint power allocation procedures are considered for the proposed single-channel equalisation method in DSL access networks. This thesis then shows that DSM can also benefit overdetermined precoding-equalisation systems, when the channel state information (CSI) parameters call for a specific decision feedback criterion to achieve a perfect reconstruction. A reasonable redundancy is introduced to reformulate the original multi-user MIMO problem into the simplest case of power management problem. DSM algorithms are primarily applied to solve the power allocation problem in DSM networks with the aim of maximising the system attribute rather than meeting specific requirements. Also, a powerful PMD algorithm known as sequential matrix diagonalisation (SMD) is used for analysing the eigenvalue decomposition problem by quantifying the available system resource including the effects of the crosstalk and its parameters. This analysis is carried out through joint precoding and equalisation structures. The thesis also investigates dynamic interference mitigation strategies for improving the performance of DSL networks. Two different mitigation strategies through a decision feedback equalisation (DFE) criterion are considered, including zero-forcing (ZF) and minimum mean square error (MMSE) equalisers. The difference between ZF and MMSE equalisations is analysed. Some experimental simulation results demonstrate the performance of both ZF and MMSE equalisation under the DFE equalisation constraint settings. Model reduction on the MMSE equalisation is thus applied to balance the crosstalk interference and enhance the data-rate throughput. Finally, the thesis studies a multi-user MIMO problem under the utility maximisation framework. Simulation results illustrate that the power allocation of multi-user DSL transmission can be jointly controlled and the interference can often be mitigated optimally on a single user basis. Driven by imperfect CSI information in current DSL networks, the research presents a novel DSM method that allows not only crosstalk mitigation, but also the exploitation of crosstalk environments through the fielding of versatile, flexible and evolvable systems. The proposed DSM tool is presented to achieve a robust mitigating system in any arbitrary overdetermined multi-user MIMO environment. Numerical optimisation results show that the mitigation of crosstalk impairment using the proposed DSM strategy. The design and implementation of the proposed DSM are carried out in the environment of MATLAB