Resource allocation technique for powerline network using a modified shuffled frog-leaping algorithm

Resource allocation (RA) techniques should be made efficient and optimized in order to enhance the QoS (power & bit, capacity, scalability) of high-speed networking data applications. This research attempts to further increase the efficiency towards near-optimal performance. RA’s problem involves assignment of subcarriers, power and bit amounts for each user efficiently. Several studies conducted by the Federal Communication Commission have proven that conventional RA approaches are becoming insufficient for rapid demand in networking resulted in spectrum underutilization, low capacity and convergence, also low performance of bit error rate, delay of channel feedback, weak scalability as well as computational complexity make real-time solutions intractable. Mainly due to sophisticated, restrictive constraints, multi-objectives, unfairness, channel noise, also unrealistic when assume perfect channel state is available. The main goal of this work is to develop a conceptual framework and mathematical model for resource allocation using Shuffled Frog-Leap Algorithm (SFLA). Thus, a modified SFLA is introduced and integrated in Orthogonal Frequency Division Multiplexing (OFDM) system. Then SFLA generated random population of solutions (power, bit), the fitness of each solution is calculated and improved for each subcarrier and user. The solution is numerically validated and verified by simulation-based powerline channel. The system performance was compared to similar research works in terms of the system’s capacity, scalability, allocated rate/power, and convergence. The resources allocated are constantly optimized and the capacity obtained is constantly higher as compared to Root-finding, Linear, and Hybrid evolutionary algorithms. The proposed algorithm managed to offer fastest convergence given that the number of iterations required to get to the 0.001% error of the global optimum is 75 compared to 92 in the conventional techniques. Finally, joint allocation models for selection of optima resource values are introduced; adaptive power and bit allocators in OFDM system-based Powerline and using modified SFLA-based TLBO and PSO are propose

Internet Measurement

Nowadays, TCP channel estimation is a matter of great importance, being communication network metrology the core of network performance analysis field, since it allows to interpret and understand the network behaviour through the gathered metrics. In the context of this dissertation, an open source software project, available on GitHub, was developed. It uses a client-server architecture to estimate the Bulk Transfer Capacity (BTC) and provides portability due to Java and Android clients, being able to run on computers, tablets and mobile phones. Two algorithms to measure the BTC were deployed. Their measuring capacity was analysed and optimized, supported on studies about the influence of the TCP windows. The packet train dispersion algorithm was also implemented and analysed, but it did not allow measuring significant BTC results. The performance of the tool was tested for wired and cellular wireless networks, considering all the major Portuguese network operators. The results were compared to the ones measured by the iPerf3 reference tool, considering a stop criteria based on Jain’s Fairness Index [1] in order to inject the less possible traffic into the network. The measurement results are in line with the methodology proposed by ETSI and Ofcom to monitor the bandwidth, considering fixed time transmissions, and can contribute to reduce the transmission durations required to analyse each network

Peer-to-Peer Multimedia Distribution on Radio Channel and Asymmetric Channel

This chapter is organized as follows, the scenario and the main hypotheses of the chapter are explained in section 2. Section 3 describes the peer-to-peer algorithms used to build the peer-to-peer distribution networks. In section 4 we present how is estimated the maximum delay of a peer-to-peer distribution network. In this section we present the theoretical optimum in which it is maximized the average maximum number of peers and it is minimized the average maximum delay of the peer-to-peer distribution network. Moreover the simulation results for the asymmetric channel are reported in the last part of this section. In section 5 we analyse the behaviour of the peer-to-peer algorithms in a simple radio channel. In this section we present: the radio channel characterization; the model used to establish the bit error probability of each peer of a peer-to-peer distribution network; the peer-to-peer network simulator used to simulate the behaviour of the radio channel in the peer-to-peer distribution network; the validation of the model of the peer-to-peer network in an unreliable environment (radio channel) through the simulation results; the results used to establish which peer-to-peer algorithm builds the best peer-to-peer distribution network in an unreliable environment

Resource allocation in networks via coalitional games

The main goal of this dissertation is to manage resource allocation in network engineering problems and to introduce efficient cooperative algorithms to obtain high performance, ensuring fairness and stability. Specifically, this dissertation introduces new approaches for resource allocation in Orthogonal Frequency Division Multiple Access (OFDMA) wireless networks and in smart power grids by casting the problems to the coalitional game framework and by providing a constructive iterative algorithm based on dynamic learning theory.  Software Engineering (Software)Algorithms and the Foundations of Software technolog

Policy-Based Radio Resource Management in Multicast OFDMA Systems

Η ασύρματηφασματική αποδοτικότητα είναι ένας, όλο και περισσότερο, σημαντικός παράγοντας εξαιτίας της ταχείας ανάπτυξης των ασύρματων υπηρεσιών ευρείας ζώνης. Η σχεδίαση ενός συστήματος με πολλά φέροντα, όπως είναι ένα σύστημα OFDMA,επιτρέπει στα συστήματα να έχουν υψηλή χωρητικότητα για να ικανοποιήσουν τις απαιτήσεις των υπηρεσιών ευρείας ζώνης.Αυτή η αυξημένη χωρητικότητα των συστημάτων μπορεί να βελτιστοποιηθεί περαιτέρω εκμεταλλευόμενοι καλύτερα τα χαρακτηριστικά των ασύρματων καναλιών. Ηθεμελιώδηςιδέα ενός σχήματος κατανομής πόρων είναι η αποτελεσματική κατανομή των διαθέσιμων ασύρματων πόρων, όπως είναι οι υποφορείς και η ισχύς εκπομπής, μεταξύ των χρηστών του συστήματος. Σχετικά με τα προβλήματα της κατανομής πόρων σε ασύρματα συστήματα τηλεπικοινωνιών βασισμένα στην τεχνική OFDMA, η περισσότερη έρευνα επικεντρώνεται στην αναζήτηση πολιτικών ανάθεσης υποφορέων και ισχύος. Οι διαθέσιμες τεχνικές της βιβλιογραφίας δεν μπορούν να εφαρμοστούν όπως είναι σε συστήματα πολυεκπομπής. Επιπλέον, οι υπάρχουσες τεχνικές δεν μπορούν να εφαρμοστούν αμετάβλητες σε πραγματικά συστήματα στα οποία υπάρχει μεγάλος αριθμός OFDMυποφορέων, καθώς η υπολογιστική πολυπλοκότητα είναι πολύ μεγάλη. Ο βασικός στόχος της παρούσας διπλωματικής εργασίας είναι η πρόταση ικανών μηχανισμών κατανομής των διαθέσιμων υποφορέων σε ασύρματα συστήματα πολυεκπομπής χρησιμοποιώντας την τεχνολογία OFDMA. Πιο συγκεκριμένα, σχετικά με τα συστήματα πολυεκπομπής, θεωρούμε ότι τόσο ο σταθμός βάσης όσο και κάθε χρήστης είναι εφοδιασμένοι με μοναδική κεραία και η μονάδα κατανομής δεν είναι ο υποφορέας, όπως στα συμβατικά συστήματα OFDMA, αλλά μία ομάδα γειτονικώνυποφορέων, η οποία ονομάζεται τεμάχιο, με σκοπό τη μείωση της μεγάλης υπολογιστικής πολυπλοκότητας. Ένας αποτελεσματικός αλγόριθμος προτείνεται του οποίου ο στόχος είναι η μεγιστοποίηση του συνολικού ρυθμού μετάδοσης δεδομένων με περιορισμούς στη συνολική διαθέσιμη ισχύ, στο BERανά τεμάχιο και στους αναλογικούς περιορισμούς μεταξύ των ρυθμών μετάδοσης δεδομένων των ομάδων χρηστών. Η προσομοίωση και η ανάλυση της πολυπλοκότητας που παρουσιάζονται, υποστηρίζουν τα πλεονεκτήματα της κατανομής πόρων σε συστήματα πολυεκπομπήςOFDMA τα οποία βασίζονται σε κατανομή τεμαχίων και έχουν ως στόχος την εξασφάλιση της αναλογικότητας μεταξύ των ρυθμών μετάδοσης δεδομένων των ομάδων χρηστών.Wireless spectral efficiency is increasingly important due to the rapid growth of demand for high data rate wideband wireless services. The design of a multi-carrier system, such as an OFDMA system, enables high system capacity suited for these wideband wireless services. This system capacity can be further optimized with a resource allocation scheme by exploiting the characteristics of the wireless fading channels. The fundamental idea of a resource allocation scheme is to efficiently distribute the available wireless resources, such as the subcarriers and transmission power, among all admitted users in the system. Regarding the problems of resource allocation in OFDMA-based wireless communicationsystems, much of the research effort mainly focuses on finding efficient power controland subcarrier assignment policies. With systems employing multicast transmission,the available schemes in literature are not always applicable. Moreover, the existing approachesare particularly inaccessible in practical systems in which there are a large numberof OFDM subcarriers being utilized, as the required computational burden is prohibitivelyhigh. The ultimate goal of this Thesis is therefore to propose affordable mechanisms toflexibly and effectively share out the available resources in multicast wireless systems deployingOFDMA technology. Specifically, according to multicast system, it is assumed thatboth the BS and each user are equipped witha single antenna and the allocation unit is not the subcarrier,as in conventional OFDMA systems, but a set of contiguoussubcarriers, which is called chunk, in order to alleviate the heavy computational burden. An efficient algorithmis proposed whose aim is to maximize the total throughput subject to constraints on totalavailable power,BER over a chunk, and proportional data rates constraints among multicast groups. Simulation and complexity analysis are provided to support thebenefits of chunk-based resource allocation to multicast OFDMA systems with targeting proportional data rates among multicast groups

Distributed multimedia systems

A distributed multimedia system (DMS) is an integrated communication, computing, and information system that enables the processing, management, delivery, and presentation of synchronized multimedia information with quality-of-service guarantees. Multimedia information may include discrete media data, such as text, data, and images, and continuous media data, such as video and audio. Such a system enhances human communications by exploiting both visual and aural senses and provides the ultimate flexibility in work and entertainment, allowing one to collaborate with remote participants, view movies on demand, access on-line digital libraries from the desktop, and so forth. In this paper, we present a technical survey of a DMS. We give an overview of distributed multimedia systems, examine the fundamental concept of digital media, identify the applications, and survey the important enabling technologies.published_or_final_versio

Optimization and Performance Analysis of High Speed Mobile Access Networks

The end-to-end performance evaluation of high speed broadband mobile access networks is the main focus of this work. Novel transport network adaptive flow control and enhanced congestion control algorithms are proposed, implemented, tested and validated using a comprehensive High speed packet Access (HSPA) system simulator. The simulation analysis confirms that the aforementioned algorithms are able to provide reliable and guaranteed services for both network operators and end users cost-effectively. Further, two novel analytical models one for congestion control and the other for the combined flow control and congestion control which are based on Markov chains are designed and developed to perform the aforementioned analysis efficiently compared to time consuming detailed system simulations. In addition, the effects of the Long Term Evolution (LTE) transport network (S1and X2 interfaces) on the end user performance are investigated and analysed by introducing a novel comprehensive MAC scheduling scheme and a novel transport service differentiation model

Self-organising network management for heterogeneous LTE-advanced networks

This thesis was submitted for the award of Doctor of Philosophy and awarded by Brunel University LondonSince 2004, when the Long Term Evolution (LTE) was first proposed to be publicly available in the year 2009, a plethora of new characteristics, techniques and applications have been constantly enhancing it since its first release, over the past decade. As a result, the research aims for LTE-Advanced (LTE-A) have been released to create a ubiquitous and supportive network for mobile users. The incorporation of heterogeneous networks (HetNets) has been proposed as one of the main enhancements of LTE-A systems over the existing LTE releases, by proposing the deployment of small-cell applications, such as femtocells, to provide more coverage and quality of service (QoS) within the network, whilst also reducing capital expenditure. These principal advantages can be obtained at the cost of new challenges such as inter-cell interference, which occurs when different network applications share the same frequency channel in the network. In this thesis, the main challenges of HetNets in LTE-A platform have been addressed and novel solutions are proposed by using self-organising network (SON) management approaches, which allows the cooperative cellular systems to observe, decide and amend their ongoing operation based on network conditions. The novel SON algorithms are modelled and simulated in OPNET modeler simulation software for the three processes of resource allocation, mobility management and interference coordination in multi-tier macro-femto networks. Different channel allocation methods based on cooperative transmission, frequency reuse and dynamic spectrum access are investigated and a novel SON sub-channel allocation method is proposed based on hybrid fractional frequency reuse (HFFR) scheme to provide dynamic resource allocation between macrocells and femtocells, while avoiding co-tier and cross-tier interference. Mobility management is also addressed as another important issue in HetNets, especially in hand-ins from macrocell to femtocell base stations. The existing research considers a limited number of methods for handover optimisation, such as signal strength and call admission control (CAC) to avoid unnecessary handovers, while our novel SON handover management method implements a comprehensive algorithm that performs sensing process, as well as resource availability and user residence checks to initiate the handover process at the optimal time. In addition to this, the novel femto over macro priority (FoMP) check in this process also gives the femtocell target nodes priority over the congested macrocells in order to improve the QoS at both the network tiers. Inter-cell interference, as the key challenge of HetNets, is also investigated by research on the existing time-domain, frequency-domain and power control methods. A novel SON interference mitigation algorithm is proposed, which is based on enhanced inter-cell interference coordination (eICIC) with power control process. The 3-phase power control algorithm contains signal to interference plus noise ratio (SINR) measurements, channel quality indicator (CQI) mapping and transmission power amendments to avoid the occurrence of interference due to the effects of high transmission power. The results of this research confirm that if heterogeneous systems are backed-up with SON management strategies, not only can improve the network capacity and QoS, but also the new network challenges such as inter-cell interference can also be mitigated in new releases of LTE-A network

Adaptive relay techniques for OFDM-based cooperative communication systems

Cooperative communication has been considered as a cost-effective manner to exploit the spatial diversity, improve the quality-of-service and extend transmission coverage. However, there are many challenges faced by cooperative systems which use relays to forward signals to the destination, such as the accumulation of multipath channels, complex resource allocation with the bidirectional asymmetric traffic and reduction of transmission efficiency caused by additional relay overhead. In this thesis, we aim to address the above challenges of cooperative communications, and design the efficient relay systems. Starting with the channel accumulation problem in the amplify-and-forward relay system, we proposed two adaptive schemes for single/multiple-relay networks respectively. These schemes exploit an adaptive guard interval (GI) technique to cover the accumulated delay spread and enhance the transmission efficiency by limiting the overhead. The proposed GI scheme can be implemented without any extra control signal. Extending the adaptive GI scheme to multiple-relay systems, we propose a relay selection strategy which achieves the trade-off between the transmission reliability and overhead by considering both the channel gain and the accumulated delay spread. We then consider resource allocation problem in the two-way decode-and-forward relay system with asymmetric traffic loads. Two allocation algorithms are respectively investigated for time-division and frequency-division relay systems to maximize the end-to-end capacity of the two-way system under a capacity ratio constraint. For the frequency-division systems, a balanced end-to-end capacity is defined as the objective function which combines the requirements of maximizing the end-to-end capacity and achieving the capacity ratio. A suboptimal algorithm is proposed for the frequency-division systems which separates subcarrier allocation and time/power allocation. It can achieve the similar performance with the optimal one with reduced complexity. In order to further enhance the transmission reliability and maintaining low processing delay, we propose an equalize-and-forward (EF) relay scheme. The EF relay equalizes the channel between source and relay to eliminate the channel accumulation without signal regeneration. To reduce the processing time, an efficient parallel structure is applied in the EF relay. Numerical results show that the EF relay exhibits low outage probability at the same data rate as compared to AF and DF schemes

Energy-efficient dynamic resource allocation with energy harvesting nodes

The allocation of radio resources where nodes are battery constrained.[ANGLÈS] In wireless communications, there is a trend to deploy shorter-distance networks to cope with the high demanding necessities of bit-rate that current applications require. In such networks, the power needed for transmission is considerably low, due to proximity between base station and mobile terminals. As a consequence, complex baseband algorithms for signal processing and radio frequency circuitry require an amount of power that is comparable or even higher than the power for transmisson. Moreover, energy harvesting techniques, which allows user to collect energy from the environment, are being emerged as a potential solution for battery durability. In this master thesis, the allocation of radio resources in such a scenario is addressed. Nodes are considered to be battery-powered devices with an energy harvesting source that allows them to recharge their batteries. Nodes feed back their battery status information jointly with the channel state information to the scheduler, which makes a resource allocation based on all the energy constraints of the problem and not only taking the transmitted power and the channel state information as in classical approaches. The final objective is to carry out a design of scheduling algorithms able to provide a longer lifetime network, where lifetime is defined to be the period of time till the first node runs out of battery. In the first part of the thesis we consider some simplifications. Flat-fading channels are assumed and the classical rate-power Shannon's formula is used. As a result, continuous power assignment and Gaussian constellations are considered. Resource allocation problems are reformulated as convex optimization problems, which are solved using powerful software packages, or algorithms based on Lagrange duality developed in this master thesis. In the second part of the thesis, a more practical approach is carried out. Now, finite-size constellations, such as QAM constellations are considered. Therefore, a discrete rate-power function based on BER requirements is proposed. Generally, these allocation problems are not convex. Optimum solutions are computationally prohibited due to brute force search time consuming techniques. We propose greedy-like algorithms to cope this problem, where subcarriers, bit allocation and power are assigned dynamically, according to a given objective and energy constraints. From simulation results, we conclude that by using the techniques proposed in the master thesis, not only it is possible to enhance the network lifetime, but also the average bit-rate achieved by the network terminals compared with classical approaches.[CASTELLÀ] Existe una tendencia en comunicaciones sin cables a desplegar redes para cubrir distancias más cortas, con el objetivo de cubrir las necesidades de bit-rate que las actuales aplicaciones requieren. Sin embargo, en tales redes, la potencia necesitada en la transmisión es considerablemente baja, debido a la proximidad entre la estación base y los terminales móviles. Como consecuencia, los complejos algoritmos de procesado de señal de banda base y los circuitos de radio frecuencia requieren un consumo energético comparable o incluso mayor que el necesitado en transmisión. Además, técnicas de harvesting están siendo desarrolladas como soluciones potenciales a incrementar la durabilidad de las baterías. En esta máster tesis, se lleva a cabo el diseño de asignación de recursos radio en el escenario planteado anteriormente. Los terminales son considerados dispositivos con batería finita, previstos de una fuente de harvesting de energía que les permite recargar las baterías cada cierto tiempo. Los terminales envían sus estados de las baterías junto con la estimación del canal al scheduler, el cual realiza una asignación de recursos teniendo en cuenta todo el gasto energético tanto de los algoritmos de procesado como de la circuitería de RF además de la potencia en transmisión, y no sólo de la útlima junto con la estimación del canal, como sucede en diseños clásicos. El objetivo final es llevar a cabo un diseño de algoritmos de scheduling que sean capaces de alargar la vida útil de la red, donde vida útil se define como el periodo de tiempo transcurrido hasta que el primero terminal se queda sin batería. En la primera parte de la tesis se asumen algunas simplificaciones. Canales planos en frecuencia y una función continua de Shannon que relaciona bit-rate y potencia son utilizados. Como resultado, asignación continuo de potencia y constelaciones Gaussianas son consideradas. Los problemas de asignación de recursos son reformulados como problemas de optimización convexa, los cuales son resueltos mediante paquetes de software o algoritmos basados en dualidad de Lagrange desarrollados en esta tesis de máster. En la segunda parte de la tesis se llevan a cabo diseños más realistas y prácticos. Ahora se consideran constelaciones de dimensión finita, como por ejemplo modulaciones del tipo QAM. Ello hace que, funciones rate-potencia sean discretas y basadas en requerimientos de BER. Generalmente, estos problemas de asignación de recursos no son convexos. Las soluciones óptimas suelen ser computacionalmente prohibitivas debido a la extensa búsqueda que se tiene que realizar. Es por ello que se proponen algoritmos de tipo greedy para solucionar el problema de la búsqueda exhaustiva, donde portadoras, asignación de bits y potencia son asignadas de forma dinámica, en función de un objetivo y de las restricciones de energía. Mediante los datos obtenidos en las simulaciones, podemos concluir que usando las técnicas propuestas en esta tesis, no sólo es posible incrementar el tiempo de vida de la red, sino que además es posible incrementar el bit-rate medio conseguido por los terminales de la red comparado con técnicas clásicas de asignación de recursos.[CATALÀ] Existeix una tendència en comunicacions sense cables que consisteix en desplegar xarxes per cobrir distàncies més curtes, amb l'objectiu d'assolir les necessitats de bit-rate que les aplicacions actuals requereixen. No obstant, en aquestes xarxes, la potència necessària en transmissió és considerablement més baixa a causa de la proximitat entre l'estació base i els terminals mòbils. Com a conseqüència, els complexos algorismes de processament del senyal de banda base i els circuits de ràdio freqüència requereixen un consum energètic comparable o fins i tot major al necessari en transmissió. A més a més, s'estan desenvolupant tècniques de harvesting com a una solució potencial en incrementar la durabilitat de les bateries. En aquesta tesis de màster, es du a terme el disseny d'assignació de recursos ràdio en l'escenari plantejat anteriorment. Els terminals són considerats dispositius amb bateria finita, proporcionats d'una font de harvesting d'energia que els permet recarregar les bateries cada cert període de temps. Els terminals envien els estats de les bateries juntament amb l'estimació del canal al sheduler. Aquest realitza una assignació de recursos considerant totes les despeses energètiques, tant dels algorismes de processament com dels circuits de ràdio freqüència com també de la potència de transmissió, i no solament de l'última juntament amb l'estimació del canal, com succeeix en dissenys clàssics. L'objectiu final és dur a terme un disseny d'algorismes de scheduling que siguin capaços d'allargar la vida útil a la xarxa, on vida útil es defineix com el període de temps transcorregut fins que el primer terminal esgota la bateria. En la primera part de la tesi s'assumeixen algunes simplificacions. Aquestes són, canals plans en freqüència i una funció contínua de Shannon que relaciona el bit-rate i la potència. Així doncs, es considera una assignació contínua d'ample de banda, de potència, bit-rate mitjançant constel·lacions Gaussianes. Els problemes d'assignació de recursos són reformulats com problemes d'optimització convexa, els quals es resolen mitjançant paquets de software o algorismes desenvolupats en aquesta tesi basats en la dualitat de Lagrange. En la segona part, s'estudien dissenys més realistes i pràctics. En aquesta segona part es consideren constel·lacions de dimensió finita, com per exemple, modulacions de tipus QAM. Com a conseqüència, funcions de rate-potencia esdevenen discretes i basades en requeriments de BER. Generalment, aquests problemes d'assignació de recursos no són convexos. Les solucions òptimes solen ser computacionalment prohibitives a causa de l'extensa cerca que s'ha de realitzar. És per aquesta raó que es proposen algorismes de tipus greedy per solucionar el problema de la cerca exhaustiva, on portadores, assignació de bits i potència s'assignen de forma dinàmica en funció de les restriccions d'energia. Mitjançant les dades obtingudes en les simulacions, es pot concloure que, utilitzant les tècniques proposades en aquesta tesi, no només és possible incrementar el temps de vida de la xarxa, sinó que, a més a més, és possible incrementar el bit-rate mitjà aconseguit pels terminals de la xarxa comparat amb les tècniques clàssiques d'assignació de recursos