23 research outputs found
Software defined radio : a system engineering view of platform architecture and market diffusion
Thesis (S.M.)--Massachusetts Institute of Technology, System Design & Management Program, 2002.Includes bibliographical references (p. 179-181).As complexity and ambiguity in products and customer needs increase, existing companies are being forced toward new organizational models. New products require integrating knowledge across technologies, architectures, and functions in new ways, building product platforms that can adapt to changes in markets and product design throughout the product development process. In particular, the wireless telecommunications industry is plagued by multiple incompatible dominant second-generation standards, with each with separate migration paths to future third generation functionality. The high initial investments in spectrum and infrastructure, and corresponding switching costs, call out for a technological solution that can both evolve with the rapid advances in technology and potentially operates seamlessly across multiple incompatible networks to unify a highly fragmented system. In a system engineering context, this thesis investigates the use of software define radio technology (SDR) as a potential replacement for hardware solutions to the multiple air interface standard problem. This thesis investigates the role of product platform architectures in product market diffusion by studying the selection of appropriate system and product architectures, product market diffusion, and the formation of a system dominant design. Using software defined radio (SDR) technology in the wireless telecommunications industry as a case study, the emergence of SDR as a potential replacement for multiple mobile phone standards is investigated. Compared with interim compatibility solutions that combine multiple air interfaces through hardware. SDRs are an emerging technology that promises to combine multiple air-interfaces into a single wireless phone platform though software configuration. Market and organizational disruptions are determined, and how platform architecture concepts can be used to mitigate these disruptions. The history of the wireless telecommunications industry is presented to highlight the determinants of product and standards success in the wireless industry. The transition between first-generation (1G) wireless, second-generation (2G) wireless, and the interim high data rate second-generation (2.5 G) system currently being rolled out is discussed. Geographical differences in standards acceptance and the role of government policies are discussed. The strong network effects in the industry are illustrated by the late success of GSM technology in the United States market. The mode of technological standard interaction or competition is determined through the use of the Lotka-Volterra model of technological interaction and lessons learned applied to third generation systems. Plans for third generation (3G) wireless are presented, and the various transition paths from 2G to 3G are discussed. The challenges of transitioning between technologies (technological discontinuities) are highlighted through a discussion of the installed base of legacy equipment. Software defined radio (SDR) technology is presented, and a platform architecture is developed in the context of 3G market penetration. The use of appropriate flexible SDR system architectures in light of rapidly changing technological and market innovations is discussed.by Moise N. Solomon.S.M
Spectrum sharing and management techniques in mobile networks
Το φάσμα συχνοτήτων αποδεικνύεται σπάνιο κομμάτι για τους πόρους ενός κινητού
δικτύου το οποίο πρέπει να ληφθεί υπόψιν στη σχεδίαση τηλεπικοινωνιακών
συστημάτων 5ης γενιάς. Επιπλέον οι πάροχοι κινητών δικτύων θα πρέπει να
επαναπροσδιορίσουν επιχειρησιακά μοντέλα τα οποία μέχρι τώρα δεν θεωρούνταν
αναγκαία (π.χ., γνωσιακά ραδιοδίκτυα), ή να εξετάσουν την υιοθέτηση νέων
μοντέλων που αναδεικνύονται (π.χ., αδειοδοτούμενη από κοινού πρόσβαση) ώστε να
καλύψουν τις ολοένα αυξανόμενες ανάγκες για εύρος ζώνης. Ο μερισμός φάσματος
θεωρείται αναπόφευκτος για συστήματα 5G και η διατριβή παρέχει λύση για
προσαρμοστικό μερισμό φάσματος με πολλαπλά καθεστώτα εξουσιοδότησης, βάσει ενός
καινοτόμου αρχιτεκτονικού πλαισίου το οποίο επιτρέπει στα δικτυακά στοιχεία να
λαμβάνουν αποφάσεις για απόκτηση φάσματος. Η προτεινόμενη διαδικασία λήψης
αποφάσεων είναι μία καινοτόμα τεχνική προσαρμοστικού μερισμού φάσματος
βασιζόμενη σε ελεγκτές ασαφούς λογικής που καθορίζονν το καταλληλότερο σχήμα
μερισμού φάσματος και σε ενισχυμένη μάθηση που ρυθμίζει τους κανόνες ασαφούς
λογικής, στοχεύοντας να βρει τη βέλτιστη πολιτική που πρέπει να ακολουθεί ο
πάροχος ώστε να προσφέρει την επιθυμητή ποιότητα υπηρεσιών στους χρήστες,
διατηρώντας πόρους (οικονομικούς ή ραδιοπόρους) όπου είναι εφικτό. Η τελευταία
συνεισφορά της διατριβής είναι ένας μηχανισμός που εξασφαλίζει δίκαιη πρόσβαση
σε φάσμα ανάμεσα σε χρήστες σε σενάρια στα οποία η εκχώρηση άδειας χρήσης
φάσματος δεν είναι προαπαιτούμενη.Radio spectrum has loomed out to be a scarce resource that needs to be
carefully considered when designing 5G communication systems and Mobile Network
Operators (MNOs) will need to revisit business models that were not of their
prior interest (e.g. Cognitive Radio) or consider adopting new business models
that emerge (e.g. Licensed Shared Access) so as to cover the extended capacity
needs. Spectrum sharing is considered unavoidable for 5G systems and this
thesis provides a solution for adaptive spectrum sharing under multiple
authorization regimes based on a novel architecture framework that enables
network elements to proceed in decisions for spectrum acquisition. The decision
making process for spectrum acquisition proposed is a novel Adaptive Spectrum
Sharing technique that uses Fuzzy Logic controllers to determine the most
suitable spectrum sharing option and reinforcement learning to tune the fuzzy
logic rules, aiming to find an optimal policy that MNO should follow in order
to offer the desirable Quality of Service to its users, while preserving
resources (either economical, or radio) when possible. The final contribution
of this thesis is a mechanism that ensures fair access to spectrum among the
users in scenarios in which conveying spectrum license is not prerequisite
Mobile and Wireless Communications
Mobile and Wireless Communications have been one of the major revolutions of the late twentieth century. We are witnessing a very fast growth in these technologies where mobile and wireless communications have become so ubiquitous in our society and indispensable for our daily lives. The relentless demand for higher data rates with better quality of services to comply with state-of-the art applications has revolutionized the wireless communication field and led to the emergence of new technologies such as Bluetooth, WiFi, Wimax, Ultra wideband, OFDMA. Moreover, the market tendency confirms that this revolution is not ready to stop in the foreseen future. Mobile and wireless communications applications cover diverse areas including entertainment, industrialist, biomedical, medicine, safety and security, and others, which definitely are improving our daily life. Wireless communication network is a multidisciplinary field addressing different aspects raging from theoretical analysis, system architecture design, and hardware and software implementations. While different new applications are requiring higher data rates and better quality of service and prolonging the mobile battery life, new development and advanced research studies and systems and circuits designs are necessary to keep pace with the market requirements. This book covers the most advanced research and development topics in mobile and wireless communication networks. It is divided into two parts with a total of thirty-four stand-alone chapters covering various areas of wireless communications of special topics including: physical layer and network layer, access methods and scheduling, techniques and technologies, antenna and amplifier design, integrated circuit design, applications and systems. These chapters present advanced novel and cutting-edge results and development related to wireless communication offering the readers the opportunity to enrich their knowledge in specific topics as well as to explore the whole field of rapidly emerging mobile and wireless networks. We hope that this book will be useful for students, researchers and practitioners in their research studies
Optimizing Network Access Selection in Wireless Heterogeneous Networks using Velocity, Location, Policy and Qos Details
As the interest in 4G communication systems continues to grow, both academia and industry agree that a symbiotic relationship between various wireless systems is required to provide continuous broadband coverage to mobile users. It is generally accepted that a single wireless access technology alone will be incapable of meeting the various requirements of mobility, data rate and coverage in the future. Future wireless systems are envisioned as being heterogeneous in that they will include a combination of various wireless access technologies such as 3G, WLAN, and WiMAX and will have a common IP core. To fully utilize the various resources and maintain seamless connectivity in the future heterogeneous wireless environment, intelligent handoff schemes that are flexible, scalable and proactive are essential. Therefore, a new handoff decision method, one that works in a novel business model--Heterogeneous Wireless Service Provider (HWSP)--was developed with an aim to improve the mobile user's user experience. More effort was spent to achieve a good level of user satisfaction, by making the entire selection process automatic, and the user oblivious of the underlying network selection intricacies. The algorithm is able to make the final network decision, based on any particular user's speed, location, QoS demands and preference policies. This allows the algorithm to prevent unwanted handoffs and reduce the cost associated with connecting to suboptimal networks
Técnicas de pré-codificação para sistemas multicelulares coordenados
Doutoramento em TelecomunicaçõesCoordenação Multicélula é um tópico de investigação em rápido
crescimento e uma solução promissora para controlar a interferência entre
células em sistemas celulares, melhorando a equidade do sistema e
aumentando a sua capacidade. Esta tecnologia já está em estudo no LTEAdvanced
sob o conceito de coordenação multiponto (COMP). Existem
várias abordagens sobre coordenação multicélula, dependendo da
quantidade e do tipo de informação partilhada pelas estações base, através
da rede de suporte (backhaul network), e do local onde essa informação é
processada, i.e., numa unidade de processamento central ou de uma forma
distribuída em cada estação base.
Nesta tese, são propostas técnicas de pré-codificação e alocação de
potência considerando várias estratégias: centralizada, todo o
processamento é feito na unidade de processamento central; semidistribuída,
neste caso apenas parte do processamento é executado na
unidade de processamento central, nomeadamente a potência alocada a
cada utilizador servido por cada estação base; e distribuída em que o
processamento é feito localmente em cada estação base. Os esquemas
propostos são projectados em duas fases: primeiro são propostas soluções
de pré-codificação para mitigar ou eliminar a interferência entre células,
de seguida o sistema é melhorado através do desenvolvimento de vários
esquemas de alocação de potência. São propostas três esquemas de
alocação de potência centralizada condicionada a cada estação base e com
diferentes relações entre desempenho e complexidade. São também
derivados esquemas de alocação distribuídos, assumindo que um sistema
multicelular pode ser visto como a sobreposição de vários sistemas com
uma única célula. Com base neste conceito foi definido uma taxa de erro
média virtual para cada um desses sistemas de célula única que compõem
o sistema multicelular, permitindo assim projectar esquemas de alocação
de potência completamente distribuídos.
Todos os esquemas propostos foram avaliados em cenários realistas,
bastante próximos dos considerados no LTE. Os resultados mostram que
os esquemas propostos são eficientes a remover a interferência entre
células e que o desempenho das técnicas de alocação de potência
propostas é claramente superior ao caso de não alocação de potência. O
desempenho dos sistemas completamente distribuídos é inferior aos
baseados num processamento centralizado, mas em contrapartida podem
ser usados em sistemas em que a rede de suporte não permita a troca de
grandes quantidades de informação.Multicell coordination is a promising solution for cellular wireless systems
to mitigate inter-cell interference, improving system fairness and
increasing capacity and thus is already under study in LTE-A under the
coordinated multipoint (CoMP) concept. There are several coordinated
transmission approaches depending on the amount of information shared
by the transmitters through the backhaul network and where the
processing takes place i.e. in a central processing unit or in a distributed
way on each base station.
In this thesis, we propose joint precoding and power allocation techniques
considering different strategies: Full-centralized, where all the processing
takes place at the central unit; Semi-distributed, in this case only some
process related with power allocation is done at the central unit; and Fulldistributed,
where all the processing is done locally at each base station.
The methods are designed in two phases: first the inter-cell interference is
removed by applying a set of centralized or distributed precoding vectors;
then the system is further optimized by centralized or distributed power
allocation schemes. Three centralized power allocation algorithms with
per-BS power constraint and different complexity tradeoffs are proposed.
Also distributed power allocation schemes are proposed by considering
the multicell system as superposition of single cell systems, where we
define the average virtual bit error rate (BER) of interference-free single
cell system, allowing us to compute the power allocation coefficients in a
distributed manner at each BS.
All proposed schemes are evaluated in realistic scenarios considering LTE
specifications. The numerical evaluations show that the proposed schemes
are efficient in removing inter-cell interference and improve system
performance comparing to equal power allocation. Furthermore, fulldistributed
schemes can be used when the amounts of information to be
exchanged over the backhaul is restricted, although system performance is
slightly degraded from semi-distributed and full-centralized schemes, but
the complexity is considerably lower. Besides that for high degrees of
freedom distributed schemes show similar behaviour to centralized ones
Proceedings of the Fifth International Mobile Satellite Conference 1997
Satellite-based mobile communications systems provide voice and data communications to users over a vast geographic area. The users may communicate via mobile or hand-held terminals, which may also provide access to terrestrial communications services. While previous International Mobile Satellite Conferences have concentrated on technical advances and the increasing worldwide commercial activities, this conference focuses on the next generation of mobile satellite services. The approximately 80 papers included here cover sessions in the following areas: networking and protocols; code division multiple access technologies; demand, economics and technology issues; current and planned systems; propagation; terminal technology; modulation and coding advances; spacecraft technology; advanced systems; and applications and experiments
Radio Communications
In the last decades the restless evolution of information and communication technologies (ICT) brought to a deep transformation of our habits. The growth of the Internet and the advances in hardware and software implementations modified our way to communicate and to share information. In this book, an overview of the major issues faced today by researchers in the field of radio communications is given through 35 high quality chapters written by specialists working in universities and research centers all over the world. Various aspects will be deeply discussed: channel modeling, beamforming, multiple antennas, cooperative networks, opportunistic scheduling, advanced admission control, handover management, systems performance assessment, routing issues in mobility conditions, localization, web security. Advanced techniques for the radio resource management will be discussed both in single and multiple radio technologies; either in infrastructure, mesh or ad hoc networks
Recent Advances in Wireless Communications and Networks
This book focuses on the current hottest issues from the lowest layers to the upper layers of wireless communication networks and provides "real-time" research progress on these issues. The authors have made every effort to systematically organize the information on these topics to make it easily accessible to readers of any level. This book also maintains the balance between current research results and their theoretical support. In this book, a variety of novel techniques in wireless communications and networks are investigated. The authors attempt to present these topics in detail. Insightful and reader-friendly descriptions are presented to nourish readers of any level, from practicing and knowledgeable communication engineers to beginning or professional researchers. All interested readers can easily find noteworthy materials in much greater detail than in previous publications and in the references cited in these chapters
Channel assembling policies for heterogeneous fifth generation (5G) cognitive radio networks.
Doctor of Philosophy in Electronic Engineering. University of KwaZulu-Natal, Durban 2016.Abstract available in PDF file
Advanced Trends in Wireless Communications
Physical limitations on wireless communication channels impose huge challenges to reliable communication. Bandwidth limitations, propagation loss, noise and interference make the wireless channel a narrow pipe that does not readily accommodate rapid flow of data. Thus, researches aim to design systems that are suitable to operate in such channels, in order to have high performance quality of service. Also, the mobility of the communication systems requires further investigations to reduce the complexity and the power consumption of the receiver. This book aims to provide highlights of the current research in the field of wireless communications. The subjects discussed are very valuable to communication researchers rather than researchers in the wireless related areas. The book chapters cover a wide range of wireless communication topics