45 research outputs found
Spectrum Sharing for LTE-A and DTT: Field Trials of an Indoor LTE-A Femtocell in DVB-T2 Service Area
(c) 2016 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works.In this paper, we study a particular case which goes a step beyond the previous ones, as it aims at sharing the same frequency band in the same area between long term evolution-advance (LTE-A) and digital video broadcasting-terrestrial second generation (DVB-T2) technologies. Those geographical areas that are not covered because the useful DTT signal is obstructed by the environment or it has a limited coverage by the network design can be called micro-TVWS. We assume that a DVB-T2 transmitter provides coverage for fixed rooftop reception as a primary service, to a building in which a LTE-A femtocell is installed indoors for local coverage, as a secondary service. The results have been obtained by laboratory emulation and validated through field measurements using professional equipment. Our results provide the technical restrictions of the LTE-A femtocell, mainly on the maximum allowable effective isotropic radiated power that could transmit on the DTT band in terms of carrier separation, from co-channel to adjacent band. These results meet the need of spectrum for IMT-Advanced technologies, so spectrum sharing is proposed in this paper as a new solution to make an efficient use of this resource.This work was supported in part by the Ministerio de Educacion y Ciencia, Spain, under Grant "DEFINE5G" TEC2014-60258-C2-1-R and Grant "ARCO5G" TEC2014-56469-REDT, and in part by the European FEDER Funds.MartĂnez PinzĂłn, G.; Cardona Marcet, N.; GarcĂa Pardo, C.; FornĂ©s Leal, A.; Ribadeneira-RamĂrez, JA. (2016). Spectrum Sharing for LTE-A and DTT: Field Trials of an Indoor LTE-A Femtocell in DVB-T2 Service Area. IEEE Transactions on Broadcasting. 62(3):552-561. https://doi.org/10.1109/TBC.2016.2582338S55256162
Impacto do comportamento transitório de sistemas de radiocomunicaçÔes na gestão do espectro
Doutoramento em Engenharia EletrotĂ©cnicaThis PhD Thesis falls within the domain of spectrum engineering and spectrum management, and intends to address current and concrete problems, with which, regulators have to deal. Particularly, the definition of technical conditions to be met by radio systems, which will operate in specific bands, selected to introduce novel concepts such as flexibility and technological neutrality. The Block Edge Mask approach was adopted to define technical conditions of operation, in those bands. However, this model, based on spectral masks, which are defined in the frequency domain, do not take into account the transient behavior or time-varying characteristics of signals used by emerging radio communication systems. Furthermore, measurement methodologies developed for validation of technical parameters associated to these models, which are recommended by international bodies, potentially lead to practical issues that must be scrutinized. Thus, alternative time-frequency mixed domain signal processing techniques are explored, in this thesis, to be used for assessing the compliance of radio systems operating under such constraints.Esta Tese de Doutoramento insere-se nos domĂnios da engenharia do espectro e da gestĂŁo do espectro radioelĂ©trico, e pretende abordar problemas atuais e concretos com que os reguladores se deparam. Em particular, a definição de condiçÔes tĂ©cnicas a serem cumpridas pelos sistemas rĂĄdio que irĂŁo operar em determinadas faixas de frequĂȘncias, selecionadas para a introdução de abordagens de gestĂŁo do espectro mais flexĂveis e tecnologicamente neutras. O modelo de MĂĄscara Delimitadora de Bloco (Block Edge Mask) foi adotado, a nĂvel europeu, como estratĂ©gia de definição de condiçÔes tĂ©cnicas de operação, nessas faixas. Contudo, este modelo, que recorre a restriçÔes que sĂŁo apenas estabelecidas no domĂnio da frequĂȘncia, nĂŁo entra em linha de conta com comportamentos transitĂłrios ou com a variabilidade temporal de sinais inerentes aos sistemas de radiocomunicaçÔes atuais. Para alĂ©m disso, a medição e validação de parĂąmetros tĂ©cnicos associados a estes modelos, conforme definidas nas recomendaçÔes internacionais aplicĂĄveis, levantam problemas prĂĄticos que importa escalpelizar. Nesse sentido, sĂŁo exploradas, nesta tese, tĂ©cnicas alternativas de processamento de sinal no domĂnio misto tempo-frequĂȘncia, tendo em vista a sua utilização na avaliação de conformidade dos sistemas rĂĄdio em face das restriçÔes aplicĂĄveis
Models of Control Channels in the LTE System
DizertaÄnĂ prĂĄce se zabĂœvĂĄ zpracovĂĄnĂm signĂĄlu fyzickĂœch ĆĂdicĂch kanĂĄlĆŻ systĂ©mu LTE a vyĆĄetĆovĂĄnĂm bitovĂ© chybovosti pĆi pĆenosu ĆĂdicĂ informace z vysĂlaÄe do pĆijĂmaÄe v zĂĄvislosti na podmĂnkĂĄch pĆĂjmu. PrĂĄce je rozdÄlena do dvou hlavnĂch ÄĂĄstĂ. PrvnĂ ÄĂĄst prĂĄce je zamÄĆena na simulaci pĆenosu ĆĂdicĂ informace LTE v zĂĄkladnĂm pĂĄsmu. Jsou zde prezentovĂĄny vytvoĆenĂ© simulĂĄtory ĆĂdicĂch kanĂĄlĆŻ ve smÄru uplink i downlink. Simulace jsou provedeny pro vĆĄechny druhy nastavenĂ systĂ©mu a zĂĄkladnĂ modely pĆenosovĂ©ho prostĆedĂ. Jsou zde popsĂĄny vĂœsledky vlivu pouĆŸitĂ MIMO technologiĂ na kvalitu pĆĂjmu ĆĂdicĂ informace pĆedevĆĄĂm v ĂșnikovĂœch kanĂĄlech. DruhĂĄ ÄĂĄst prĂĄce je zamÄĆena na moĆŸnost nasazenĂ systĂ©mu LTE ve sdĂlenĂ©m pĂĄsmu ISM (2.4 GHz). Jsou zde pĆedstaveny zĂĄkladnĂ koncepce pouĆŸitĂ, na jejichĆŸ zĂĄkladÄ je vytvoĆen scĂ©nĂĄĆ simulacĂ. Kapitola dĂĄle popisuje tvorbu simulĂĄtoru koexistence LTE a systĂ©mu Wi-Fi v pĆenesenĂ©m pĂĄsmu ISM 2.4GHz. Jsou zde uvedeny vĂœsledky simulacĂ koexistence LTE a ruĆĄivĂ©ho systĂ©mu Wi-Fi provedenĂœch dle vytvoĆenĂ©ho scĂ©nĂĄĆe. VĂœsledky simulacĂ koexistence LTE a Wi-Fi jsou ovÄĆeny mÄĆenĂm v laboratornĂch podmĂnkĂĄch. Toto porovnĂĄnĂ je dĆŻleĆŸitĂ© z hlediska optimalizace simulĂĄtoru koexistence. Dle vĂœsledkĆŻ obou typĆŻ simulacĂ a mÄĆenĂ jsou stanovena provoznĂ doporuÄenĂ, kterĂĄ majĂ pĆispÄt k bezpeÄnĂ©mu a spolehlivĂ©mu vysĂlĂĄnĂ a pĆĂjmu ĆĂdicĂch informacĂ LTE i pĆi nepĆĂznivĂœch podmĂnkĂĄch pĆĂjmu.The doctoral thesis is focused on a signal processing in the LTE physical control channels and performance analysis of control information transmission according to receiving conditions. The thesis is divided into two parts. The first part deals with simulation of the transmission of control information in baseband. The created simulators for uplink and downlink are presented. The simulations are performed for all possible system settings and various channel models. The MIMO influence on a quality of control information reception under fading channels is also presented. The second part of the thesis is focused on LTE utilization in shared channel ISM (2.4 GHz). The basic LTE application concept for ISM band is presented. This concept is fundamental to created simulation scenario. The chapter also presents the LTE and Wi-Fi coexistence simulator in 2.4 GHz ISM passband. The coexistence simulation are presented according to simulation scenario and the results are shown. The simulated coexistence analysis results are verified in laboratory environment. The comparison of the simulated and the measured coexistence analysis results is crucial for further optimization of the coexistence simulator. Recommendations for optimal and reliable operation of LTE are specified according to the simulated and the measured results. Recommendations should be useful to the reliable transmission of LTE control information in bad receiving conditions.
Enhanced Spectrum Sensing for Cognitive Cellular Systems
This dissertation aims at improving spectrum sensing algorithms in order to effectively apply
them to cellular systems. In wireless communications, cellular systems occupy a significant
part of the spectrum. The spectrum usage for cellular systems are rapidly expanding due to the
increasing demand for wireless services in our society. This results in radio frequency spectrum
scarcity. Cellular systems can effectively handle this issue through cognitive mechanisms for
spectrum utilization. Spectrum sensing plays the first stage of cognitive cycles for the adaptation
to radio environments.
This dissertation focuses on maximizing the reliability of spectrum sensing to satisfy
regulation requirements with respect to high spectrum sensing performance and an acceptable
error rate. To overcome these challenges, characteristics of noise and manmade signals are
exploited for spectrum sensing. Moreover, this dissertation considers system constraints, the
compatibility with the current and the trends of future generations. Newly proposed and existing
algorithms were evaluated in simulations in the context of cellular systems. Based on a prototype
of cognitive cellular systems (CCSs), the proposed algorithms were assessed in realistic scenarios.
These algorithms can be applied to CCSs for the awareness of desired signals in licensed and
unlicensed bands.
For orthogonal frequency-division multiplexing (OFDM) signals, this dissertation exploits
the characteristics of pilot patterns and preambles for new algorithms. The new algorithms
outperform the existing ones, which also utilize pilot patterns. Additionally, the new algorithms
can work with short observation durations, which is not possible with the existing algorithms. The
Digital Video Broadcasting - Terrestrial (DVB-T) standard is taken as an example application for
the algorithms. The algorithms can also be developed for filter bank multicarrier (FBMC) signals,
which are a potential candidate for multiplexing techniques in the next cellular generations. The
experimental results give insights for the reliability of the algorithms, taking system constraints
v
into account. Another new sensing algorithm, based on a preamble, is proposed for the DVBT2
standard, which is the second generation of of DVB system. DVB-T2 systems have been
deployed in worldwide regions. This algorithm can detect DVB-T2 signals in a very short
observation interval, which is helpful for the in-band sensing mode, to protect primary users (in
nearly real-time) from the secondary transmission.
An enhanced spectrum sensing algorithm based on cyclostationary signatures is proposed
to detect desired signals in very low signal-to-noise ratios (SNRs). This algorithm can be
developed to detect the single-carrier frequency division multiple access (SC-FDMA) signal,
which is adopted for the uplink of long-term evolution (LTE) systems. This detector substantially
outperforms the existing detection algorithms with the marginal complexity of some scalar
multiplications. The test statistics are explicitly formulated in mathematical formulas, which
were not presented in the previous work. The formulas and simulation results provide a useful
strategy for cyclostationarity-based detection with different modulation types.
For multiband spectrum sensing, an effective scheme is proposed not only to detect but
also to classify LTE signals in multiple channels in a wide frequency range. To the best of our
knowledge, no scheme had previously been described to perform the sensing tasks. The scheme is
reliable and flexible for implementation, and there is almost no performance degradation caused
by the scheme compared to single-channel spectrum sensing. The multiband sensing scheme was experimentally assessed in scenarios where the existing infrastructures are interrupted to
provide mobile communications.
The proposed algorithms and scheme facilitate cognitive capabilities to be applied to real
cellular communications. This enables the significantly improved spectrum utilization of CCSs
Adaptive Interference Removal for Un-coordinated Radar/Communication Co-existence
Most existing approaches to co-existing communication/radar systems assume
that the radar and communication systems are coordinated, i.e., they share
information, such as relative position, transmitted waveforms and channel
state. In this paper, we consider an un-coordinated scenario where a
communication receiver is to operate in the presence of a number of radars, of
which only a sub-set may be active, which poses the problem of estimating the
active waveforms and the relevant parameters thereof, so as to cancel them
prior to demodulation. Two algorithms are proposed for such a joint waveform
estimation/data demodulation problem, both exploiting sparsity of a proper
representation of the interference and of the vector containing the errors of
the data block, so as to implement an iterative joint interference removal/data
demodulation process. The former algorithm is based on classical on-grid
compressed sensing (CS), while the latter forces an atomic norm (AN)
constraint: in both cases the radar parameters and the communication
demodulation errors can be estimated by solving a convex problem. We also
propose a way to improve the efficiency of the AN-based algorithm. The
performance of these algorithms are demonstrated through extensive simulations,
taking into account a variety of conditions concerning both the interferers and
the respective channel states
Recommended from our members
Integration of unidirectional technologies into wireless back-haul architecture
This thesis was submitted for the degree of Docter of Philosophy and awarded by Brunel University.Back-haul infrastructures of today's wireless operators must support the triple-play services demanded by the market or regulatory bodies. To cope with increasing capacity demand, the EU FP7 project CARMEN has developed a cost-effective heterogeneous
multi-radio wireless back-haul architecture, which may also leverage the native multicast
capabilities of broadcast technologies such as DVB-T to off-load high-bandwidth broadcast
content delivery. However, the integration of such unidirectional technologies into a packet-switched architecture requires careful considerations. The contribution of this thesis is the investigation, design and evaluation of protocols and mechanisms facilitating the integration of such unidirectional technologies into the wireless
back-haul architecture so that they can be configured and utilized by the spectrum and
capacity optimization modules. This integration mainly concerns the control plane and, in particular, the aspects related to resource and capability descriptions, neighborhood, link and Multi Protocol Label Switching (MPLS) Label-Switched Path (LSP) monitoring, unicast and multicast LSP signalling as well as topology forming and maintenance. During the course of this study we have analyzed the problem space, proposed solutions to the resulting research questions and evaluated our approach. Our results show that the now Unidirectional Technology (UDT)-aware architecture can readily consider
Unidirectional Technologies (UDTs) to distribute, for example, broadcast content
Cooperative Radio Communications for Green Smart Environments
The demand for mobile connectivity is continuously increasing, and by 2020 Mobile and Wireless Communications will serve not only very dense populations of mobile phones and nomadic computers, but also the expected multiplicity of devices and sensors located in machines, vehicles, health systems and city infrastructures. Future Mobile Networks are then faced with many new scenarios and use cases, which will load the networks with different data traffic patterns, in new or shared spectrum bands, creating new specific requirements. This book addresses both the techniques to model, analyse and optimise the radio links and transmission systems in such scenarios, together with the most advanced radio access, resource management and mobile networking technologies. This text summarises the work performed by more than 500 researchers from more than 120 institutions in Europe, America and Asia, from both academia and industries, within the framework of the COST IC1004 Action on "Cooperative Radio Communications for Green and Smart Environments". The book will have appeal to graduates and researchers in the Radio Communications area, and also to engineers working in the Wireless industry. Topics discussed in this book include: âą Radio waves propagation phenomena in diverse urban, indoor, vehicular and body environmentsâą Measurements, characterization, and modelling of radio channels beyond 4G networksâą Key issues in Vehicle (V2X) communicationâą Wireless Body Area Networks, including specific Radio Channel Models for WBANsâą Energy efficiency and resource management enhancements in Radio Access Networksâą Definitions and models for the virtualised and cloud RAN architecturesâą Advances on feasible indoor localization and tracking techniquesâą Recent findings and innovations in antenna systems for communicationsâą Physical Layer Network Coding for next generation wireless systemsâą Methods and techniques for MIMO Over the Air (OTA) testin