Final report on the evaluation of RRM/CRRM algorithms

Deliverable public del projecte EVERESTThis deliverable provides a definition and a complete evaluation of the RRM/CRRM algorithms selected in D11 and D15, and evolved and refined on an iterative process. The evaluation will be carried out by means of simulations using the simulators provided at D07, and D14.Preprin

Gestão comum de recursos rádio em redes sem fios de próxima geração

Mestrado em Electrónica e TelecomunicaçõesA tecnologia de sinais de rádio frequência sobre fibra óptica involve o uso de links ópticos para transportar os sinais desde a unidade central de processamento até aos sites remotos (e vice-versa). A centralização do processamento dos sinais de rádio frequência permite a partilha de equipamentos, alocação dinâmica de recursos e uma manutenção mais simplificada do sistema. Embora o conceito de gestão comum dos recursos rádio tenha despertado grande interesse na comunidade científica em termos da melhor utilização desses recursos e de novos modelos de negócio, a verdade é que a sua implementação não tem sido fácil. A interligação entre diferentes componentes de rede, normalmente localizados em locais diferentes, introduz um grande atraso nas comunicações; por outro lado as implementações proprietárias e a escassez de informação global não satisfazem os requisitos de um ambiente extremamente dinâmico, como é o ambiente wireless. Uma topologia centralizada permite ultrapassar estas contrariedades, disponibilizando uma interligação eficiente entre as entidades locais e comuns de gestão de recursos rádio. Nesta dissertação é apresentada uma nova arquitectura de gestão comum de recursos rádio, baseada no conceito de interligação entre diferentes tecnologias de acesso. Esta arquitectura faz a gestão dos recursos rádio de forma centralizada, onde os sinais rádio chegam sem qualquer pré-processamento. Essa arquitectura é avaliada com a implementação de um algoritmo simples de balanceamento da carga que segue a politica de minimização da interferência e aumento da capacidade. As simulações com duas tecnologias de acesso, quando consideradas separas ou em agregado, mostraram um aumento do débito de pelo menos 51% para o mesmo valor de interferência enquanto que o erro de simbolo decresce pelo menos 20%.Radio over fibre technology involves the use of optical fibre links to distribute radio frequency signals from a central location to remote sites (and viceversa). The centralisation of radio frequency signals processing functions enables equipment sharing, dynamic allocation of resources, and simplified system operation and maintenance. Despite the unquestionable interest concept of common radio resource management from the point of view of resource usage and novel business models, its implementation has not been easy. The interworking between the different local radio resource management entities, usually located on different places will not satisfy the requirements of the wireless dynamic behaviour due to increase of delay in communication process, less information availability and proprietary implementations. A centralised topology can overcome the drawbacks of former wireless systems architecture interconnection by providing an efficient common radio communication flow with the local radio resource management entities. In this thesis a novel common radio resource management architecture is presented based on the concept of inter-working between different technologies. This is a centralised architecture where the radio frequency signals are delivered to the central location through the optical links. The new architecture is evaluated with a common policy that minimises interference while the overall system capacity is increased. The policy is implemented through the load balancing algorithm. The simulations of two radio access technologies when separately and jointly considered show that when the load balancing algorithm is applied the available throughput increases in at least 51% while the symbol error rate decreases at least 20%

Code-division multiplexing

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2004.Includes bibliographical references (p. 395-404).(cont.) counterpart. Among intra-cell orthogonal schemes, we show that the most efficient broadcast signal is a linear superposition of many binary orthogonal waveforms. The information set is also binary. Each orthogonal waveform is generated by modulating a periodic stream of finite-length chip pulses with a receiver-specific signature code that is derived from a special class of binary antipodal, superimposed recursive orthogonal code sequences. With the imposition of practical pulse shapes for carrier modulation, we show that multi-carrier format using cosine functions has higher bandwidth efficiency than the single-carrier format, even in an ideal Gaussian channel model. Each pulse is shaped via a prototype baseband filter such that when the demodulated signal is detected through a baseband matched filter, the resulting output samples satisfy the Generalized Nyquist criterion. Specifically, we propose finite-length, time overlapping orthogonal pulse shapes that are g-Nyquist. They are derived from extended and modulated lapped transforms by proving the equivalence between Perfect Reconstruction and Generalized Nyquist criteria. Using binary data modulation format, we measure and analyze the accuracy of various Gaussian approximation methods for spread-spectrum modulated (SSM) signalling ...We study forward link performance of a multi-user cellular wireless network. In our proposed cellular broadcast model, the receiver population is partitioned into smaller mutually exclusive subsets called cells. In each cell an autonomous transmitter with average transmit power constraint communicates to all receivers in its cell by broadcasting. The broadcast signal is a multiplex of independent information from many remotely located sources. Each receiver extracts its desired information from the composite signal, which consists of a distorted version of the desired signal, interference from neighboring cells and additive white Gaussian noise. Waveform distortion is caused by time and frequency selective linear time-variant channel that exists between every transmitter-receiver pair. Under such system and design constraints, and a fixed bandwidth for the entire network, we show that the most efficient resource allocation policy for each transmitter based on information theoretic measures such as channel capacity, simultaneously achievable rate regions and sum-rate is superposition coding with successive interference cancellation. The optimal policy dominates over its sub-optimal alternatives at the boundaries of the capacity region. By taking into account practical constraints such as finite constellation sets, frequency translation via carrier modulation, pulse shaping and real-time signal processing and decoding of finite-length waveforms and fairness in rate distribution, we argue that sub-optimal orthogonal policies are preferred. For intra-cell multiplexing, all orthogonal schemes based on frequency, time and code division are equivalent. For inter-cell multiplexing, non-orthogonal code-division has a larger capacity than its orthogonalby Ceilidh Hoffmann.Ph.D

Nonorthogonal Multiple Access for 5G and Beyond

This work was supported in part by the U.K. Engineering and Physical Sciences Research Council (EPSRC) under Grant EP/N029720/1 and Grant EP/N029720/2. The work of L. Hanzo was supported by the ERC Advanced Fellow Grant Beam-me-up

3G Wideband CDMA : packet-based optimisation for high data-rate downlink transmission

A third generation (3G) of mobile communication systems, based on Wideband CDMA, are intended to offer high-speed packet-based services. Network operators wish to maximise the throughput in the downlink of3G systems, which requires efficient allocation ofresources. This thesis considers the problem ofmaximising throughput in an interference dominated channel. Cooperative broadcasting is a theoretical technique to mitigate this problem. Its implementation in practical systems requires efficient resource allocati.on to maximise the thr(oughput whilst meeting system and user-imposed constramts. A resource allocation approach is presented for implementing cooperative broadcasting. Users are paired and a teclmique for allocating resources between the pair is developed. Then, a method for pairing the users is considered. Simulation results are presented, which show a throughput improvement over existing resource allocation approaches. The problem ofcontrolling the distribution ofrandomly arriving data to meet the resource allocation specifications is examined. A single-threshold buffer is proposed, which requires fewer calculations than an existing double-threshold buffer. Simulation results are presented which show a throughput improvement may be realised, greater than that which would achievable using other rate control schemes. Cooperative broadcasting may lead to transmissions to some users being allocated low power. When full channel infonnation is available at the transmitter, a water filling solution may be used to maximise capacity. However, when combined with buffer management, erasure may result. This erasure may be overcome using an erasure protection code. Such a code is examined. When combined with Turbo coding, ajoint detector may be used for providing error and erasure protection. Analysis ofthis detector shows a lower limit on the error rate, dependent on the probability of erasure. Simulation results show that using this approach the error rate is significantly improved. This code can then be used to increase capacity, whilst achieving low error rates.Imperial Users onl

Adaptive scheduling in cellular access, wireless mesh and IP networks

Networking scenarios in the future will be complex and will include fixed networks and hybrid Fourth Generation (4G) networks, consisting of both infrastructure-based and infrastructureless, wireless parts. In such scenarios, adaptive provisioning and management of network resources becomes of critical importance. Adaptive mechanisms are desirable since they enable a self-configurable network that is able to adjust itself to varying traffic and channel conditions. The operation of adaptive mechanisms is heavily based on measurements. The aim of this thesis is to investigate how measurement based, adaptive packet scheduling algorithms can be utilized in different networking environments. The first part of this thesis is a proposal for a new delay-based scheduling algorithm, known as Delay-Bounded Hybrid Proportional Delay (DBHPD), for delay adaptive provisioning in DiffServ-based fixed IP networks. This DBHPD algorithm is thoroughly evaluated by ns2-simulations and measurements in a FreeBSD prototype router network. It is shown that DBHPD results in considerably more controllable differentiation than basic static bandwidth sharing algorithms. The prototype router measurements also prove that a DBHPD algorithm can be easily implemented in practice, causing less processing overheads than a well known CBQ algorithm. The second part of this thesis discusses specific scheduling requirements set by hybrid 4G networking scenarios. Firstly, methods for joint scheduling and transmit beamforming in 3.9G or 4G networks are described and quantitatively analyzed using statistical methods. The analysis reveals that the combined gain of channel-adaptive scheduling and transmit beamforming is substantial and that an On-off strategy can achieve the performance of an ideal Max SNR strategy if the feedback threshold is optimized. Finally, a novel cross-layer energy-adaptive scheduling and queue management framework EAED (Energy Aware Early Detection), for preserving delay bounds and minimizing energy consumption in WLAN mesh networks, is proposed and evaluated with simulations. The simulations show that our scheme can save considerable amounts of transmission energy without violating application level QoS requirements when traffic load and distances are reasonable

Contribución a la planificación sistémica de redes móviles 4G

El objetivo de esta Tesis consiste en el diseño, implementación y prueba de algoritmos, tanto convencionales –utilizados actualmente en la industria– como otros novedosos basados en Computación Evolutiva, que constituyan una contribución novedosa a la planificación sistémica de redes móviles LTE. En particular, se centra en el dimensionamiento estratégico de la red de acceso de LTE, debido a que constituye aproximadamente el 60% de la inversión total, e incluso una parte más elevada de los gastos OPEX (operating expense). La Tesis establece una novedosa propuesta para el problema de asignación o asociación de usuarios a eNBs (evolved NBs) en LTE. La contribución es este aspecto es doble: por un lado, se plantea un nuevo método para asociar N_U usuarios a N_B eNBs en redes LTE. Consiste éste en modelar la asociación usuario-eNB como un problema de optimización combinatoria en el que la función a minimizar es una métrica novedosa conocida como “Tiempo de descarga total del sistema” –Download Time of the complete System (DTS). La minimización de DTS se traduce en una asignación de usuarios a celdas más eficiente que la que se consigue con métodos convencionales como el basado en maximizar CQI (Channel Quality Indicator) o en balanceo de carga (Load Balancing –LB–). Permite la asignación de usuarios desde celdas que, de otra forma, estarían sobrecargadas a otras con menos carga. Esto tiene un doble beneficio, tanto para el operador como para los usuarios. Por una parte, ayudar al operador de red a utilizar sus recursos de una manera más equilibrada y rentable. Por otra parte, la estrategia propuesta reduce el tiempo de descarga para la mayoría de los usuarios, e introduce cierta equidad en el reparto de recursos. La minimización de DTS es un problema de gran complejidad computacional. Ésta es justamente la razón que ha motivado la segunda contribución de esta Tesis: abordar el problema de la minimización de DTS mediante un algoritmo evolutivo (EA). El aspecto más interesante del EA propuesto es la forma en la que se realiza la codificación de las soluciones (asignaciones usuario-celda) candidatas. El cromosoma es un vector de dimensión N_U en el que cada elemento representa un usuario. El elemento en la posición j contiene cierta información sobre el usuario u_j. Esa información es un número entero que representa a qué eNB de los N_U disponibles se ha asignado dicho usuario. Los operadores de mutación, cruce y selección se han diseñado para que puedan trabajar con esta codificación. El operador de cruce, en particular, es un torneo de todos contra todos. El otro aspecto novedoso de la implementación del algoritmo evolutivo propuesto se encuentra en la población inicial. Como se tiene información de una solución sub-óptima del problema (la proporcionada por el método convencional basado en CQI –que asigna un usuario al eNB para el cual tiene mejor CQI–), se incluye ésta en la población inicial, y el resto de los individuos se genera, básicamente, aplicando los operadores de mutación y cruce sobre esa solución. En cualquier caso, la solución encontrada (asociación de cada usuario a un eNB) es mejor (menor DTS) que la asignación realizada con métodos convencionales. El segundo conjunto de contribuciones de la Tesis consiste en el diseño de una herramienta de planificación estratégica LTE, centrada en el proceso de dimensionado de red en un entorno multiusuario y multiservicio, y en la que se ha integrado en módulo EA de asociación usuario-eNB. Mediante esta integración, dicha herramienta, permite realizar comparativas entre el enfoque propuesto de asignación en base al EA y otros métodos convencionales, integrados en la herramienta, como los basados en CQI y en LB. En concreto, la herramienta tiene (1) una parametrización sencilla y eficaz de los múltiples parámetros de entrada y de la ubicación inicial de los eNB, que (2) permite simular un entorno multi-servicio y multi-usuario, empleando (3) diferentes algoritmos de asociación usuario-eNB –como el propuesto en la Tesis– y (4) varios algoritmos de scheduling, de forma que (5) se garantiza el cumplimiento del requisito de Velocidad de Descarga Mínima de cada servicio. Para cumplir los requisitos (1)–(5), la herramienta calcula la velocidad media de los servicios ofertados, teniendo en cuenta los tiempos de descarga de cada uno de los usuarios. Si con el número de eNB, calculados previamente, se cumple el requisito de velocidad demandada por los distintos servicios simulados, entonces se dará́ por válido dicho valor. En caso de incumplimiento, se añaden eNBs de forma iterativa hasta cumplir el requisito anterior. Ninguna de las herramientas disponibles en el mercado, tanto comerciales como basadas en software libre, es capaz de cumplir estos requisitos. Para cuantificar en qué medida la herramienta desarrollada, en general, y nuestra propuesta de asignación usuario-celda, en particular, son útiles en el dimensionamiento de LTE, se han llevado a cabo un conjunto amplio y variado de simulaciones, en diferentes escenarios realistas, tanto urbano como urbano denso, y se han comparado con dos métodos de asignación usuario-celda convencionales basados en CQI y en LB. Estos experimentos muestran que el método propuesto supera claramente a los convencionales, especialmente en áreas urbanas y urbana densa (entornos donde la asignación es más crítica en términos de capacidad) con macro-celdas de LTE, e incluso, en escenarios que modelan redes heterogéneas y ultra densas. La herramienta y los algoritmos que se proponen en esta tesis pueden ayudar a los operadores a mejorar sus diseños previos al despliegue y a cuantificar la mejora potencial que se conseguiría en la red al añadir un nuevo nodo. Los resultados de la investigación realizada en la Tesis se han publicando en varias revistas y congresos internacionales

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