290 research outputs found
A survey of self organisation in future cellular networks
This article surveys the literature over the period of the last decade on the emerging field of self organisation as applied to wireless cellular communication networks. Self organisation has been extensively studied and applied in adhoc networks, wireless sensor networks and autonomic computer networks; however in the context of wireless cellular networks, this is the first attempt to put in perspective the various efforts in form of a tutorial/survey. We provide a comprehensive survey of the existing literature, projects and standards in self organising cellular networks. Additionally, we also aim to present a clear understanding of this active research area, identifying a clear taxonomy and guidelines for design of self organising mechanisms. We compare strength and weakness of existing solutions and highlight the key research areas for further development. This paper serves as a guide and a starting point for anyone willing to delve into research on self organisation in wireless cellular communication networks
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
Load balancing using cell range expansion in LTE advanced heterogeneous networks
The use of heterogeneous networks is on the increase, fueled by consumer demand for more data. The main objective of heterogeneous networks is to increase capacity. They offer solutions for efficient use of spectrum, load balancing and improvement of cell edge coverage amongst others. However, these solutions have inherent challenges such as inter-cell interference and poor mobility management. In heterogeneous networks there is transmit power disparity between macro cell and pico cell tiers, which causes load imbalance between the tiers. Due to the conventional user-cell association strategy, whereby users associate to a base station with the strongest received signal strength, few users associate to small cells compared to macro cells. To counter the effects of transmit power disparity, cell range expansion is used instead of the conventional strategy. The focus of our work is on load balancing using cell range expansion (CRE) and network utility optimization techniques to ensure fair sharing of load in a macro and pico cell LTE Advanced heterogeneous network. The aim is to investigate how to use an adaptive cell range expansion bias to optimize Pico cell coverage for load balancing. Reviewed literature points out several approaches to solve the load balancing problem in heterogeneous networks, which include, cell range expansion and utility function optimization. Then, we use cell range expansion, and logarithmic utility functions to design a load balancing algorithm. In the algorithm, user and base station associations are optimized by adapting CRE bias to pico base station load status. A price update mechanism based on a suboptimal solution of a network utility optimization problem is used to adapt the CRE bias. The price is derived from the load status of each pico base station. The performance of the algorithm was evaluated by means of an LTE MATLAB toolbox. Simulations were conducted according to 3GPP and ITU guidelines for modelling heterogeneous networks and propagation environment respectively. Compared to a static CRE configuration, the algorithm achieved more fairness in load distribution. Further, it achieved a better trade-off between cell edge and cell centre user throughputs. [Please note: this thesis file has been deferred until December 2016
A Review of Cellular Networks: Applications, Benefits and Limitations
Over decades the world has witnessed stepwise evolution in Cellular networks technology and mobile network industry which have transformed nation’s economy and created job opportunities since 1970. The stepwise evolution of the cellular networks from first generation (1G) to fifth generation (5G) have shown tremendous increase in technology, benefits, user demand and applications. As new generation of cellular network unfold, the challenges and limitations of preceded generations are being tackled as always depicted in the design architecture of each new generation. The first generation (1G) cellular network was based on analogue and was able to cater for mobile voice transmission but posed some challenges in terms of quality of service and security of network. Second generation (2G) came with the introduction of digitally encrypted technology and greater security for sender and receiver with services such as text messages and MMS. Third generation (3G) was developed to offer high speed data and multimedia connections to subscribers. Fourth generation evolves from 3G with higher data rate, lower latency, greater spectral efficiency and simple protocol architecture with efficient multicast than its predecessors. Fifth-generation (5G) networks is being deployed to meet growing demands for data from consumer and industrial users and to enable the use of advanced technologies such as smart city applications, autonomous vehicles and navigation. The envisioned sixth generation (6G) of cellular network is expected to witness an unparalleled revolution that would significantly distinguish it from the existing generations and will drastically re-shape the wireless evolution from "connected thing to connected intelligence. This paper provides a comprehensive review of cellular networks applications and challenges from 1G to 6G. Keywords: 1G, 2G, 3G, 4G, 5G, 6G, Applications  Benefits, and Limitations DOI: 10.7176/NCS/11-04 Publication date: December 31st 202
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 Ăłpticos 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 cientĂfica 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
interferĂŞncia 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 interferĂŞncia 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%
Improving relay based cellular networks performance in highly user congested and emergency situations
PhDRelay based cellular networks (RBCNs) are the technologies that incorporate multi-hop communication into traditional cellular networks. A RBCN can potentially support higher data rates, more stable radio coverage and more dynamic services. In reality, RBCNs still suffer from performance degradation in terms of high user congestion, base station failure and overloading in emergency situations. The focus of this thesis is to explore the potential to improve IEEE802.16j supported RBCN performance in user congestion and emergency situations using adjustments to the RF layer (by antenna adjustments or extensions using multi-hop) and cooperative adjustment algorithms, e.g. based on controlling frequency allocation centrally and using distributed approaches. The first part of this thesis designs and validates network reconfiguration algorithms for RBCN, including a cooperative antenna power control algorithm and a heuristic antenna tilting algorithm. The second part of this thesis investigates centralized and distributed dynamic frequency allocation for higher RBCN frequency efficiency, network resilience, and computation simplicity. It is demonstrated that these benefits mitigate user congestion and base station failure problems significantly. Additionally, interweaving coordinated dynamic frequency allocation and antenna tilting is investigated in order to obtain the benefits of both actions. The third part of this thesis incorporates Delay Tolerate Networking (DTN) technology into RBCN to let users self-organize to connect to functional base station through multi-hops supported by other users. Through the use of DTN, RBCN coverage and performance are improved. This thesis explores the augmentation of DTN routing protocols to let more un-covered users connect to base stations and improve network load balancin
An intelligent-agent approach for managing congestion in W-CDMA networks
PhDResource Management is a crucial aspect in the next generation cellular networks
since the use of W-CDMA technology gives an inherent flexibility in managing the
system capacity. The concept of a “Service Level Agreement” (SLA) also plays a
very important role as it is the means to guarantee the quality of service provided to
the customers in response to the level of service to which they have subscribed.
Hence there is a need to introduce effective SLA-based policies as part of the radio
resource management.
This work proposes the application of intelligent agents in SLA-based control in
resource management, especially when congestion occurs. The work demonstrates the
ability of intelligent agents in improving and maintaining the quality of service to
meet the required SLA as the congestion occurs.
A particularly novel aspect of this work is the use of learning (here Case Based
Reasoning) to predict the control strategies to be imposed. As the system environment
changes, the most suitable policy will be implemented. When congestion occurs, the
system either proposes the solution by recalling from experience (if the event is
similar to what has been previously solved) or recalculates the solution from its
knowledge (if the event is new). With this approach, the system performance will be
monitored at all times and a suitable policy can be immediately applied as the system
environment changes, resulting in maintaining the system quality of service
- …