56 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
Resource Sharing via Planed Relay for HWN
We present an improved version of adaptive distributed cross-layer routing algorithm (ADCR) for hybrid wireless network with dedicated relay stations () in this paper. A mobile terminal (MT) may borrow radio resources that are available thousands mile away via secure multihop RNs, where RNs are placed at pre-engineered locations in the network. In rural places such as mountain areas, an MT may also communicate with the core network, when intermediate MTs act as relay node with mobility. To address cross-layer network layers routing issues, the cascaded ADCR establishes routing paths across MTs, RNs, and cellular base stations (BSs) and provides appropriate quality of service (QoS). We verify the routing performance benefits of over other networks by intensive simulation
Performance analysis of a hybrid topology CDD/TDD-CDMA network architecture
Student Number : 0006936H -
MSc research report -
School of Electrical and Information Engineering -
Faculty of Engineering and the Built EnvironmentCode division duplexing (CDD) has steadily garnered attention in the telecommunication
community. In this project report we propose a physical layer implementation of CDD that
utilizes orthogonal Gold codes as the means of differentiating transmission directions, in
order to implement an ad-hoc networking infrastructure that is overlaid on a standard mobile
networking topology, and hence creating a hybrid networking topology. The performance of
the CDD based system is then comparatively assessed in two ways: from the perspective of
the physical layer using point-to-point simulations and from the perspective of the network
layer using an iterative snapshot based simulation where node elements are able to setup
connections based on predefined rules
Architecture design for disaster resilient management network using D2D technology
Huge damages from natural disasters, such as earthquakes, floods, landslide, tsunamis, have been reported in recent years, claiming many lives, rendering millions homeless and causing huge financial losses worldwide. The lack of effective communication between the public rescue/safety agencies, rescue teams, first responders and trapped survivors/victims makes the situation even worse. Factors like dysfunctional communication networks, limited communications capacity, limited resources/services, data transformation and effective evaluation, energy, and power deficiency cause unnecessary hindrance in rescue and recovery services during a disaster. The new wireless communication technologies are needed to enhance life-saving capabilities and rescue services. In general, in order to improve societal resilience towards natural catastrophes and develop effective communication infrastructure, innovative approaches need to be initiated to provide improved quality, better connectivity in the events of natural and human disasters.
In this thesis, a disaster resilient network architecture is proposed and analysed using multi-hop communications, clustering, energy harvesting, throughput optimization, reliability enhancement, adaptive selection, and low latency communications. It also examines the importance of mode selection, power management, frequency and time resource allocation to realize the promises of Long-term Evolution (LTE) Device to Device (D2D) communication. In particular, to support resilient and energy efficient communication in disaster-affected areas.
This research is examined by thorough and vigorous simulations and validated through mathematical modelling. Overall, the impact of this research is twofold: i) it provides new technologies for effective inter- and intra-agency coordination system during a disaster event by establishing a stronger and resilient communication; and ii) It offers a potential solution for stakeholders such as governments, rescue teams, and general public with new informed information on how to establish effective policies to cope with challenges before, during and after the disaster events
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Application priority framework for fixed mobile converged communication networks
This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.The current prospects in wired and wireless access networks, it is becoming increasingly important to address potential convergence in order to offer integrated broadband services. These systems will need to offer higher data transmission capacities and long battery life, which is the catalyst for an everincreasing variety of air interface technologies targeting local area to wide area connectivity. Current integrated industrial networks do not offer application aware context delivery and enhanced services for optimised networks. Application aware services provide value-added functionality to business applications by capturing, integrating, and consolidating intelligence about users and their endpoint devices from various points in the network. This thesis mainly intends to resolve the issues related to ubiquitous application aware service, fair allocation of radio access, reduced energy consumption and improved capacity. A technique that measures and evaluates the data rate demand to reduce application response time and queuing delay for multi radio interfaces is proposed. The technique overcomes the challenges of network integration, requiring no user intervention, saving battery life and selecting the radio access connection for the application requested by the end user. This study is split in two parts. The first contribution identifies some constraints of the services towards the application layer in terms of e.g. data rate and signal strength. The objectives are achieved by application controlled handover (ACH) mechanism in order to maintain acceptable data rate for real-time application services. It also looks into the impact of the radio link on the application and identifies elements and parameters like wireless link quality and handover that will influence the application type. It also identifies some enhanced traditional mechanisms such as distance controlled multihop and mesh topology required in order to support energy efficient multimedia applications. The second contribution unfolds an intelligent application priority assignment mechanism (IAPAM) for medical applications using wireless sensor networks. IAPAM proposes and evaluates a technique based on prioritising multiple virtual queues for the critical nature of medical data to improve instant transmission. Various mobility patterns (directed, controlled and random waypoint) has been investigated and compared by simulating IAPAM enabled mobile BWSN. The following topics have been studied, modelled, simulated and discussed in this thesis: 1. Application Controlled Handover (ACH) for multi radios over fibre 2. Power Controlled Scheme for mesh multi radios over fibre using ACH 3. IAPAM for Biomedical Wireless Sensor Networks (BWSN) and impact of mobility over IAPAM enabled BWSN. Extensive simulation studies are performed to analyze and to evaluate the proposed techniques. Simulation results demonstrate significant improvements in multi radios over fibre performance in terms of application response delay and power consumption by upto 75% and 15 % respectively, reduction in traffic loss by upto 53% and reduction in delay for real time application by more than 25% in some cases
Scalable and interference aware wi-fi mesh networks using cots devices
A crescente tendencia no acesso mĂłvel tem sido potenciada pela tecnologia IEEE 802.11. Contudo, estas redes tĂŞm alcance rádio limitado. Para a extensĂŁo da sua cobertura Ă© possĂvel recorrer a redes emalhadas sem fios baseadas na tecnologia IEEE 802.11, com vantagem do ponto de vista do custo e da flexibilidade de instalação, face a soluções cabladas.
Redes emalhadas sem fios constituĂdas por nĂłs com apenas uma interface tĂŞm escalabilidade reduzida. A principal razĂŁo dessa limitação deve-se ao uso do mecanismo de acesso ao meio partilhado Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) em topologias multi-hop. Especificamente, o CSMA/CA nĂŁo evita o problema do nĂł escondido levando ao aumento do nĂşmero de colisões e correspondente degradação de desempenho com impacto direto no throughput e na latĂŞncia.
Com a redução da tecnologia rádio torna-se viável a utilização de múltiplos rádios por nó, sem com isso aumentar significativamente o custo da solução final de comunicações. A utilização de mais do que um rádio por nó de comuniações permite superar os problemas de desempenho inerentes ás redes formadas por nós com apenas um rádio.
O objetivo desta tese, passa por desenvolver uma nova solução para redes emalhadas multi-cana, duar-radio, utilizando para isso novos mecanismos que complementam os mecanismos definidos no IEEE 802.11 para o estabelecimento de um Basic Service Set (BSS). A solução é baseada na solução WiFIX, um protocolo de routing para redes emalhadas de interface única e reutiliza os mecanismos já implementados nas redes IEEE 802.11 para difundir métricas que permitam à rede escalar de forma eficaz minimizando o impacto na performance. A rede multi-hop é formada por nós equipados com duas interfaces, organizados numa topologia hierárquica sobre múltiplas relações Access Point (AP) – Station (STA).
Os resultados experimentais obtidos mostram a eficácia e o bom desempenho da solução proposta face à solução WiFIX original.The increasing trend on mobile access has been mainly potentied for IEEE 802.11 technology. However these networks suffer from reduced radio range. The extension of coverage can be potentiated by mesh deployments since they provide an ease, robust, flexible and cost effective solution for this problem. These networks are built upon nodes scattered in a mesh topology that form the backbone of an extended basic service set.
Single radio Wireless Mesh Networks (WMN) however suffer from reduced scalability. The main reason to such limitation is the use of Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) in the multi-hop topology. Specifically, CSMA/CA fails to prevent the hidden and exposed node occurrence, which respectively, lead to an increase on the number of collisions and flow retentions. The direct impact on throughput and latency reduces the overall network performance to values that no longer match user increasing demands.
As radio technology becomes cheaper, it became possible to equip nodes with multiple interfaces and operate them in multiple channels in order the reduce interference from links operating on a common channel.
Therefore the goal of this thesis is to develop a new WMN Multi-Radio Multi-Channel (MRMC) solution addressing new mechanisms not yet covered in state of art. The proposed solution, is based on WiFIX, a Single Radio (SR) WMN routing protocol and reuses the mechanisms already implemented in IEEE 802.11 networks to broadcast metrics that enable the network to auto-configure efficiently and to scale with minimum overhead. The multi-hop backbone is formed by nodes equipped with two interfaces disposed in a hierarchical topology, under multiple Access Point (AP) - Station (STA) relations.
The results obtained from an experimental testbed clearly show the effectiveness of the solution compared with the original WiFIX and its capability to scale resulting from the overhead control and co-channel interference reduction
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