Algoritmos de transferência de redes LTE em meios de transporte massivo

Handover in LTE occurs when a device moves from the cell coverage serving it towards another; a process where the user established session must not be interrupted due to this cell change. Handovers in LTE are classified as hard ones, since the link with the serving cell is interrupted before establishing the new link with the target cell. This entails a larger failure risk and, consequently, a potential deterioration in the quality of service. This article presents a review of the handover algorithms in LTE, focusing on the ones oriented to massive means of transport. We show how the new algorithms offer a larger success in handovers, increasing the networkdata rate. This indicates that factors such as speed, position, and direction should be included in the algorithms to improve the handover in means of transport. We also present the algorithms focused on mobile relays such as an important study field for future research works.El traspaso en LTE se presenta cuando un equipo pasa de la cobertura de una celda a la de otra, un proceso en el que se debe asegurar que el usuario no vea interrumpida su sesión, como efecto de ese cambio de celda. Los traspasos en LTE son del tipo duro, en ellos, el enlace con la celda servidora se interrumpe antes de establecer el nuevo enlace con la celda destino, lo que conlleva a un mayor riesgo de falla y con ello a un probable deterioro de la calidad del servicio al usuario. Este artículo revisa algoritmos de traspaso LTE, enfocándose en aquellos orientados a medios de trasporte masivo. Muestra cómo los nuevos algoritmos ofrecen una tasa mayor de traspasos exitosos y con ello una mejor tasa de transferencia de datos; evidencia que factores como la velocidad, la posición y la dirección deben ser incluidos en los algoritmos dirigidos a mejorar el traspaso en medios de transporte; y presenta a los algoritmos enfocados en relays móviles, como un importante campo de estudio para futuras investigaciones.A transferência em LTE ocorre quando um dispositivo passa da cobertura de uma célula para outra, um processo no qual deve ser assegurado que o usuário não veja sua sessão interrompida, como resultado dessa mudança de célula. As transferências em LTE são do tipo duro, nelas, o link com a célula do servidor é interrompido antes de se estabelecer o novo link com a célula alvo, o que leva a um maior risco de falha e, portanto, a uma provável deterioração da qualidade do serviço ao usuário. Este artigo revisa os algoritmos de transferência LTE, com foco naqueles orientados a meios de transporte massivo. Mostra como os novos algoritmos oferecem uma taxa maior de transferências bem-sucedidas e, com isso, uma melhor taxa de transferência de dados; evidencia de que fatores como a velocidade, a posição e a direção devem ser incluídos nos algoritmos que visam melhorar a transferência nos meios de transporte; e apresenta os algoritmos focados em relés móveis, como um importante campo de estudo para futuras pesquisas

Separation Framework: An Enabler for Cooperative and D2D Communication for Future 5G Networks

Soaring capacity and coverage demands dictate that future cellular networks need to soon migrate towards ultra-dense networks. However, network densification comes with a host of challenges that include compromised energy efficiency, complex interference management, cumbersome mobility management, burdensome signaling overheads and higher backhaul costs. Interestingly, most of the problems, that beleaguer network densification, stem from legacy networks' one common feature i.e., tight coupling between the control and data planes regardless of their degree of heterogeneity and cell density. Consequently, in wake of 5G, control and data planes separation architecture (SARC) has recently been conceived as a promising paradigm that has potential to address most of aforementioned challenges. In this article, we review various proposals that have been presented in literature so far to enable SARC. More specifically, we analyze how and to what degree various SARC proposals address the four main challenges in network densification namely: energy efficiency, system level capacity maximization, interference management and mobility management. We then focus on two salient features of future cellular networks that have not yet been adapted in legacy networks at wide scale and thus remain a hallmark of 5G, i.e., coordinated multipoint (CoMP), and device-to-device (D2D) communications. After providing necessary background on CoMP and D2D, we analyze how SARC can particularly act as a major enabler for CoMP and D2D in context of 5G. This article thus serves as both a tutorial as well as an up to date survey on SARC, CoMP and D2D. Most importantly, the article provides an extensive outlook of challenges and opportunities that lie at the crossroads of these three mutually entangled emerging technologies.Comment: 28 pages, 11 figures, IEEE Communications Surveys & Tutorials 201

Cell identity allocation and optimisation of handover parameters in self-organised LTE femtocell networks

A thesis submitted to the University of Bedfordshire in partial ful lment of the requirements for the degree of Doctor of PhilosophyFemtocell is a small cellular base station used by operators to extend indoor service coverage and enhance overall network performance. In Long Term Evolution (LTE), femtocell works under macrocell coverage and combines with the macrocell to constitute the two-tier network. Compared to the traditional single-tier network, the two-tier scenario creates many new challenges, which lead to the 3rd Generation Partnership Project (3GPP) implementing an automation technology called Self-Organising Network (SON) in order to achieve lower cost and enhanced network performance. This thesis focuses on the inbound and outbound handovers (handover between femtocell and macrocell); in detail, it provides suitable solutions for the intensity of femtocell handover prediction, Physical Cell Identity (PCI) allocation and handover triggering parameter optimisation. Moreover, those solutions are implemented in the structure of SON. In order to e ciently manage radio resource allocation, this research investigates the conventional UE-based prediction model and proposes a cell-based prediction model to predict the intensity of a femtocell's handover, which overcomes the drawbacks of the conventional models in the two-tier scenario. Then, the predictor is used in the proposed dynamic group PCI allocation approach in order to solve the problem of PCI allocation for the femtocells. In addition, based on SON, this approach is implemented in the structure of a centralised Automated Con guration of Physical Cell Identity (ACPCI). It overcomes the drawbacks of the conventional method by reducing inbound handover failure of Cell Global Identity (CGI). This thesis also tackles optimisation of the handover triggering parameters to minimise handover failure. A dynamic hysteresis-adjusting approach for each User Equipment (UE) is proposed, using received average Reference Signal-Signal to Interference plus Noise Ratio (RS-SINR) of the UE as a criterion. Furthermore, based on SON, this approach is implemented in the structure of hybrid Mobility Robustness Optimisation (MRO). It is able to off er the unique optimised hysteresis value to the individual UE in the network. In order to evaluate the performance of the proposed approach against existing methods, a System Level Simulation (SLS) tool, provided by the Centre for Wireless Network Design (CWiND) research group, is utilised, which models the structure of two-tier communication of LTE femtocell-based networks

Self organization in 3GPP long term evolution networks

Mobiele en breedbandige internettoegang is realiteit. De internetgeneratie vindt het immers normaal om overal breedbandige internettoegang te hebben. Vandaag zijn er al 5,9 miljard mobiele abonnees ( 87% van de wereldbevolking) en 20% daarvan hebben toegang tot een mobiele breedbandige internetverbinding. Dit wordt aangeboden door 3G (derde generatie) technologieën zoals HSPA (High Speed Packet Access) en 4G (vierde generatie) technologieën zoals LTE (Long Term Evolution). De vraag naar hoogkwalitatieve diensten stelt de mobiele netwerkoperatoren en de verkopers van telecommunicatieapparatuur voor nieuwe uitdagingen: zij moeten nieuwe oplossingen vinden om hun diensten steeds sneller en met een hogere kwaliteit aan te bieden. De nieuwe LTE-standaard brengt niet alleen hogere pieksnelheden en kleinere vertragingen. Het heeft daarnaast ook nieuwe functionaliteiten in petto die zeer aantrekkelijk zijn voor de mobiele netwerkoperator: de integratie van zelfregelende functies die kunnen ingezet worden bij de planning van het netwerk, het uitrollen van een netwerk en het controleren van allerhande netwerkmechanismen (o.a. handover, spreiding van de belasting over de cellen). Dit proefschrift optimaliseert enkele van deze zelfregelende functies waardoor de optimalisatie van een mobiel netwerk snel en automatisch kan gebeuren. Hierdoor verwacht men lagere kosten voor de mobiele operator en een hogere kwaliteit van de aangeboden diensten

Performance Modelling and Analysis of a New CoMP-based Handover Scheme for Next Generation Wireless Networks. Performance Modelling and Analysis for the Design and Development of a New Handover Scheme for Cell Edge Users in Next Generation Wireless Networks (NGWNs) Based on the Coordinated Multi-Point (CoMP) Joint Transmission (JT) Technique

Inter-Cell Interference (ICI) will be one of main problems for degrading the performance of future wireless networks at cell edge. This adverse situation will become worst in the presence of dense deployment of micro and macro cells. In this context, the Coordinated Multi-Point (CoMP) technique was introduced to mitigate ICI in Next Generation Wireless Networks (NGWN) and increase their network performance at cell edge. Even though the CoMP technique provides satisfactory solutions of various problems at cell edge, nevertheless existing CoMP handover schemes do not prevent unnecessary handover initialisation decisions and never discuss the drawbacks of CoMP handover technique such as excessive feedback and resource sharing among UEs. In this research, new CoMP-based handover schemes are proposed in order to minimise unnecessary handover decisions at cell edge and determine solution of drawbacks of CoMP technique in conjunction with signal measurements such as Reference Signal Received Power (RSRP) and Received Signal Received Quality (RSRQ). A combination of calculations of RSRP and RSRQ facilitate a credible decision making process of CoMP mode and handover mode at cell edge. Typical numerical experiments indicate that by triggering the CoMP mode along with solutions of drawbacks, the overall network performance is constantly increase as the number of unnecessary handovers is progressively reduced

Optimierung der Handover Entscheidung in Infrastrukturnetzen unter Verwendung von realistischen Simulationsumgebungen

The development of mobile communication services and technologies in recent years boosts the importance and ubiquity of terminal equipments in our everyday life. The main drivers for this development are the reliability of the offered services and the user friendliness, allowing a huge variety of communication services with a single device. To assure a high communication quality and the usability of the services a seamless connectivity is beneficial or even mandatory, e.g. for voice calls, video streaming, gaming or safety-critical application based on car-to-car communication. Due to the cellular nature of infrastructure networks, mobile users will cross cell boundaries and need to switch the serving cell with the help of a handover procedure. The timing of the handover is essential to keep the mobile devices connected to the network. The introduction of measurement based optimisation in the context of self-organising networks enables the optimisation of the handover decision. The key enabler for the optimisation are a cost function that incorporates the relevant handover performance indicators, a reasonable observation time to evaluate the performance and an optimisation algorithm that reliably improves the handover performance in various, ever-changing network conditions. In the recent years several handover optimisation algorithms have been investigated. Nevertheless, the influence of the target function on the optimisation, the dimensioning of the observation window and the impact of network condition changes have not been investigated so far. In this dissertation a detailed analysis of the handover performance indicators is presented. Beyond that, additional system information or measurements are valued as potential candidates to allow further improvement of the handover performance. Particular attention is paid to the ability to adapt to changing network conditions since the introduction of new cell layers (small cells), new techniques like adaptive antenna systems or spectrum sharing or the introduction of new communication technologies like LTE-Advanced increases the complexity of future mobile communication networks. Finally, we develop an optimisation algorithm that reliably and quickly optimises the handover performance in various and fast-changing network conditions.Mobile Endgeräte gewinnen in unserem täglichen Leben zunehmend an Bedeutung. Dieser Trend wird vorangetrieben durch die rasante Entwicklung der Mobilfunktechnologien und neu angebotene Dienste in den letzten Jahren. Immer mehr Dienstleistungen werden über ein einzelnes Endgerät bereitgestellt. Um eine hohe Übertragungsqualität zur Nutzung der Dienste sicherzustellen, ist eine nahtlose Verbindung zum Kommunikationsnetzwerk wünschenswert oder sogar obligatorisch, z.B. für Sprachverbindungen, Video-Streaming, Onlinespiele oder sicherheitsrelevante Anwendungen der Car-to-Car-Kommunikation. Bedingt durch die zellulare Struktur der Mobilfunknetze ist zur Aufrechterhaltung der Kommunikation ein Zellwechsel (Handover) im Randbereich des Versorgungsgebietes einer Zelle notwendig. Der genaue Zeitpunkt des Zellwechsels ist dabei von besonderer Bedeutung. Die Einführung der messungsbasierten Selbst-Optimierung für Mobilfunknetze ermöglicht die Optimierung der Zellwechsel-Entscheidung. Die wesentlichen Voraussetzungen für eine Optimierung sind eine Optimierungszielfunktion auf Basis der Leistungsindikatoren, eine angemessene Beobachtungszeit sowie die Entwicklung eines möglichst allgemeingültigen Optimierungsverfahrens. In den letzten Jahren sind viele solcher Verfahren untersucht und veröffentlicht worden. Dennoch sind der Einfluss der Zielfunktion auf die Optimierung, die Dimensionierung des Beobachtungszeitraums und die Auswirkungen von Netzzustandsänderungen auf die Optimierung bisher weitgehend vernachlässigt worden. In dieser Arbeit wird eine detaillierte Analyse der Zellwechsel-Leistungsindikatoren in LTE durchgeführt. Darüber hinaus wird die Eignung zusätzlicher Systeminformationen oder Messungen zur weiteren Verbesserung der Zellwechsel-Entscheidung untersucht. Durch die Einführung neuer Zelltypen (z.B. Small Cells), moderner Übertragungstechniken wie adaptive Antennensysteme oder die Einführung neuer Technologien wie LTE Advanced nimmt die Komplexität der zukünftigen Mobilfunknetze stetig zu. Das in dieser Arbeit entwickelte Optimierungsverfahren ermöglicht eine schnelle und zuverlässige Anpassung der Zellwechselparameter an die veränderlichen Bedingungen in den Mobilfunknetzen und kann daher auch in komplexeren Systemen eingesetzt werden

Handover Control Parameters Optimisation in LTE Networks

In the past few years, the demand for data traffic has increased explosively, in order to meet such a demand in traffic volume, small cell networks have been introduced. With the wide adoption of small cells, the densification of small cell deployment has become an unavoidable trend. However, such density in small cell deployment brings various problems for the network operators, among which the handover issue is one of the most critical. In order to tackle the handover problem in heterogeneous networks (HetNets), this thesis was mainly concerned with the system-level handover control parameters optimisation