412 research outputs found
CogCell: Cognitive Interplay between 60GHz Picocells and 2.4/5GHz Hotspots in the 5G Era
Rapid proliferation of wireless communication devices and the emergence of a
variety of new applications have triggered investigations into next-generation
mobile broadband systems, i.e., 5G. Legacy 2G--4G systems covering large areas
were envisioned to serve both indoor and outdoor environments. However, in the
5G-era, 80\% of overall traffic is expected to be generated in indoors. Hence,
the current approach of macro-cell mobile network, where there is no
differentiation between indoors and outdoors, needs to be reconsidered. We
envision 60\,GHz mmWave picocell architecture to support high-speed indoor and
hotspot communications. We envisage the 5G indoor network as a combination of-,
and interplay between, 2.4/5\,GHz having robust coverage and 60\,GHz links
offering high datarate. This requires an intelligent coordination and
cooperation. We propose 60\,GHz picocellular network architecture, called
CogCell, leveraging the ubiquitous WiFi. We propose to use 60\,GHz for the data
plane and 2.4/5GHz for the control plane. The hybrid network architecture
considers an opportunistic fall-back to 2.4/5\,GHz in case of poor connectivity
in the 60\,GHz domain. Further, to avoid the frequent re-beamforming in 60\,GHz
directional links due to mobility, we propose a cognitive module -- a
sensor-assisted intelligent beam switching procedure -- which reduces the
communication overhead. We believe that the CogCell concept will help future
indoor communications and possibly outdoor hotspots, where mobile stations and
access points collaborate with each other to improve the user experience.Comment: 14 PAGES in IEEE Communications Magazine, Special issue on Emerging
Applications, Services and Engineering for Cognitive Cellular Systems
(EASE4CCS), July 201
Design and Development of HiperLAN/2 WLANs Based Multiwavelet Signals using Adaptive Antennas Algorithm
In this paper a simple adaptive antenna idea, consisting of multiple independent omni directional receiver antennas and the ZF (Zero Forcing) algorithm for the adaptive signal processing, is applied to the HiperLAN/2 WLANs based Orthogonal Frequency-Division Multiplexing OFDM, Discrete Multiwavelet Transform (DMWT) and its performance is evaluated at link level. MATLAB modeling demonstrated that the performance with adaptive receiver antennas has a remarkable degradation in the packet (PDU or PSDU) error rate (PER) compared to without using adaptive receiver antennas due to the considerable channel models. With adaptive receiver antennas, Carrier-to-Noise Ratio (C/N) improvement compared to without using adaptive receiver antennas is achieved. The performance of the system can more improve by increasing the number of antennas at receiver. Keywords: Network, HiperLAN/2, Adaptive, OFDM, DMWT, IDMWT
Review on NEXT Generation Technologies of Wireless Communication
Cellular communication has brought in an unparalleled revolution in the field of communication during the past two decades. The mobile communication industry growth has surpassed growth of all other fields. Even o ur own country is not left behind. The number of mobile subscribers in the country rose to over 9 11 m in Mar 201 2 . 3G system has been introduced in line with other countries. Talks have started about 4G / 5G. The implementation of 4G /5G will most probably be the ultimate goal in the field of communication
ACUTA Journal of Telecommunications in Higher Education
In This Issue
5G\u27s Promise: 1,000 x Capacity, 1,000 x Challenges
Higher-Speed WLANs About to Emerge
State of the Residential Network 2013
LTE: The Next Wave of Wireless Evolution
The 10 Most Costly Pitfalls of DAS Deployment and How to Avoid Them
DAS on Campus: Solutions for Wireless Service
Decision Criteria for Selecting a Wireless lntrusion Prevention System
lnstitutional Excellence Award
President\u27s Message
From the CE
Técnicas de equalização para MIMO massivo com amplificação não linear
The dawn of the new generation of mobile communications and the trafic
explosion that derives from its implementation pose great challenge. The
milimeter wave band and the use of massive number of antennas are technologies
which, when combined, allow the transmission of high data rate,
functioning in zones of the electromagnetic spectrum that are less explored
and with capability of allocation of dozens of GHz of bandwidth.
In this dissertation we consider a massive MIMO millimeter wave system
employing a hybrid architecture, i.e., the number of transmit and receive
antennas are lower than the number of radio frequency chains. As consequence,
the precoder and equalizers should be designed in both digital and
analog domains. In the literature, most of the proposed hybrid beamforming
schemes were evaluated without considering the effects of nonlinear amplifications. However, these systems face non-avoidable nonlinear effects due
to power amplifiers functioning in nonlinear regions. The strong nonlinear
effects throughout the transmission chain will have a negative impact on the
overall system performance and thus its study and the design of equalizers
that take into account these effects are of paramount importance.
This dissertation proposes a hybrid iterative equalizer for massive MIMO millimeter
wave SC-FDMA systems. The user terminals have low complexity,
just equipped with analog precoders based on average angle of departure,
each with a single radio frequency chain. At the base station it is designed
an hybrid analog-digital iterative equalizer with fully connected architecture
in order to eliminate both the multi-user interference and the nonlinear distortion
caused by signal amplification during the transmission. The equalizer
is optimized by minimizing the bit error rate, which is equivalent to minimize
the mean square error rate. The impact of the saturation threshold of the
amplifiers in the system performance is analysed, and it is demonstrated that
the iterative process can efficiently remove the multi-user interference and
the distortion, improving the overall system performance.O surgimento de uma nova geração de comunicaçÔes móveis e a explosão
de tråfego que advém da sua implementação apresenta grandes desafios. A
banda de ondas milimétricas e o uso massivo de antenas são tecnologias que,
combinadas, permitem atingir elevadas taxas de transmissĂŁo, funcionando
em zonas do espectro electromagnético menos exploradas e com capacidade
de alocação de dezenas de GHz para largura de banda.
Nesta dissertação foi considerado um sistema de MIMO massivo de ondas
milimĂ©tricas usando uma arquitectura hĂbrida, i.e., o nĂșmero de antenas para
transmissĂŁo e recepção Ă© menor que o nĂșmero de cadeias de radiofrequĂȘncia.
Consequentemente, o pré-codificador e equalizadores devem ser projectados
nos domĂnios digital e analĂłgico. Na literatura, a maioria dos esquemas
hĂbridos de beamforming sĂŁo avaliados sem ter em conta os efeitos de nĂŁo linearidade
da amplificação do sinal. No entanto, estes sistemas sofrem
inevitavelmente de efeitos nĂŁo lineares devido aos amplificadores de potĂȘncia
operarem em regiÔes não lineares. Os fortes efeitos das não-linearidades ao
longo da cadeia de transmissĂŁo tĂȘm um efeito nefasto no desempenho do
sistema e portanto o seu estudo e projecto de equalizadores que tenham em
conta estes efeitos sĂŁo de extrema importĂąncia.
Esta dissertação propĂ”e um equalizador hĂbrido para sistemas baseados em
ondas milimétricas para MIMO massivo com modulação SC-FDMA. Os terminais
de utilizador possuem baixa complexidade, equipados apenas com
pré-codificadores analógicos baseados no ùngulo médio de partida, cada um
com uma Ășnica cadeia de radiofrequĂȘncia. Na estação base Ă© projectado
um equalizador iterativo hĂbrido analĂłgico-digital com arquitectura completamente
conectada de modo a eliminar a interferencia multi-utilizador e a
distorção causada pela amplificação do sinal aquando da transmissão. O
equalizador Ă© optimizado minimizando a taxa de erro de bit, o que Ă© equivalente
a minimizar a taxa de erro quadråtico médio. O impacto do limiar
de saturação dos amplificadores no desempenho do sistema é analisado, e é
demonstrado que o processo iterativo consegue eliminar de modo eficiente
a interferĂȘncia multi-utilizador e a distorção, melhorando o desempenho do
sistema.Mestrado em Engenharia Eletrónica e TelecomunicaçÔe
Improving Frequency Reuse and Cochannel Interference Coordination in 4G HetNets
This report describes my M.A.Sc. thesis research work. The emerging 4th generation
(4G) mobile systems and networks (so called 4G HetNets) are designed as multilayered cellular topology with a number of asymmetrically located, asymmetrically powered, self-organizing, and user-operated indoor small cell (e.g., pico/femto cells and WLANs) with a variety of cell architectures that are overlaid by a large cell (macro cell) with some or all interfering wireless links. These designs of 4G HetNets bring new challenges such as increased dynamics of user mobility and data traffic trespassing over the multi-layered cell boundaries. Traditional approaches of radio resource allocation and inter-cell (cochannel) interference management that are mostly centralized and static in the network core and are carried out pre-hand by the operator in 3G and lower cellular technologies, are liable to increased signaling overhead, latencies, complexities, and scalability issues and, thus, are not viable in case of 4G HetNets. In this thesis a comprehensive research study is carried out on improving the radio resource sharing and inter-cell interference management in 4G HetNets. The solution strategy exploits dynamic and adaptive channel allocation approaches such as dynamic and opportunistic spectrum access (DSA, OSA) techniques, through exploiting the spatiotemporal diversities among transmissions in orthogonal frequency division multiple access (OFDMA) based medium access in 4G HetNets.
In this regards, a novel framework named as Hybrid Radio Resource Sharing (HRRS) is introduced. HRRS comprises of these two functional modules: Cognitive Radio Resource Sharing (CRRS) and Proactive Link Adaptation (PLA) scheme. A dynamic switching algorithm enables CRRS and PLA modules to adaptively invoke according to whether orthogonal channelization is to be carried out exploiting the interweave channel allocation (ICA) approach or non-orthogonal channelization is to be carried out exploiting the underlay channel allocation (UCA) approach respectively when relevant conditions regarding the traffic demand and radio resource availability are met. Benefits of CRRS scheme are identified through simulative analysis in comparison to the legacy cochannel and dedicated channel deployments of femto cells respectively. The case study and numerical analysis for PLA scheme is carried out to understand the dynamics of threshold interference ranges as function of transmit powers of MBS and FBS, relative ranges of radio entities, and QoS requirement of services with the value realization of PLA scheme.1 yea
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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
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