In this paper we revisit hybrid analog-digital precoding systems with emphasis on their modelling and radio-frequency (RF) losses, to realistically evaluate their benefits in 5G system implementations. For this, we decompose the analog beamforming networks (ABFN) as a bank of commonly used RF components and formulate realistic model constraints based on their S-parameters. Specifically, we concentrate on fully-connected ABFN (FC-ABFN) and Butler networks for implementing the discrete Fourier transform (DFT) in the RF domain. The results presented in this paper reveal that the performance and energy efficiency of hybrid precoding systems are severely affected, once practical factors are considered in the overall design. In this context, we also show that Butler RF networks are capable of providing better performances than FC-ABFN for systems with a large number of RF chains.
標(biāo)簽： Analog-Digital Precoding Hybrid
上傳時(shí)間： 2020-05-27
上傳用戶：shancjb
This is believed to be the first book that takes a view of nanotechnology from a telecommunications and networking perspective. Nanotechnology refers to the manip- ulation of materials at the atomic or molecular level. Nanotechnology is getting a lot of attention of late not only in academic settings and in laboratories around the world, but also in government and venture capitalists’ initiatives. There now is a major drive to commercialize the technology by all sorts of firms, ranging from start- ups to Fortune 100 companies.
標(biāo)簽： Nanotechnology Applications
上傳時(shí)間： 2020-05-31
上傳用戶：shancjb
Spread-spectrum communication is a core area within the field of digital communication. Originally used in military networks as countermeasures against the threats of jamming and interception, spread-spectrum systems are now widely used in commercial applications and are part of several wireless and mobile communication standards. Although spread-spectrum communication is a staple topic in textbooks on digital communication, its treatment is usually cursory. This book is designed to provide a more intensive examination of the subject that is suitable for graduate students and practicing engineers with a solid background in the theory of digital communication. As the title indicates, this book stresses principles rather than specific current or planned systems, which are described in manyotherbooks.My goal in this bookis to providea concisebut lucidexplanation of the fundamentals of spread-spectrum systems with an emphasis on theoretical principles.
標(biāo)簽： Spread-Spectrum Communication Systems 2nd
上傳時(shí)間： 2020-06-01
上傳用戶：shancjb
In the two years since this book was first published, ultra wideband (UWB) has advanced and consolidated as a technology, and many more people are aware of the possibilities for this exciting technology. We too have expanded and consolidated materials in this second edition in the hope that ‘Ultra Wideband: Signals and Systems in Communication Engineering’ will continue to prove a useful tool for many students and engineers to come to an understanding of the basic technologies for UWB.
標(biāo)簽： Wideband Signals Systems Ultra and
上傳時(shí)間： 2020-06-01
上傳用戶：shancjb
Micro-Electro-Mechanical Systems (MEMS) are miniature systems composed ofintegratedelectricalandmechanicalpartstosenseand/orcontrolthingsonaμmscale. The concept of MEMS is attributed to Richard Feynman’s famous talk on December 29th, 1959 [2,3]. Dr. Feynman foresaw many aspects of future MEMS development with his insight in microphysics. In particular, material properties in the μm scale are differentfrombulkpropertiesandthescalingdownofintegratedcircuits(IC)fabrication technology has been a major driving force of MEMS development.
標(biāo)簽： Performance High MEMS RF
上傳時(shí)間： 2020-06-06
上傳用戶：shancjb
Over many years, RF-MEMS have been a hot topic in research at the technology and device level. In particular, various kinds of mechanical Si-MEMS resonators and piezoelectric BAW (bulk acoustic wave) resonators have been developed. The BAW technology has made its way to commercial products for passive RF filters, in particular for duplexers in RF transceiver front ends for cellular communica- tions. Beyond their use in filters, micromachined resonators can also be used in conjunction with active devices in innovative circuits and architectures.
標(biāo)簽： MEMS-based Circuits Systems and
上傳時(shí)間： 2020-06-06
上傳用戶：shancjb
Since the 1990s the EU has been pursuing climate change mitigation targets. Following the international commitment to the legally binding greenhouse gas reduction under the Kyoto Protocol, the 2020 policy package consists of a set of binding legislation to ensure that the EU meets its climate and energy targets for the year 2020. The package sets three key targets: 20% reduction in greenhouse gas emissions (from 1990 levels), 20% of EU energy from renewables (as well as a 10% target for renewable fuels) and 20% improvement in energy efficiency. The targets were set by EU leaders in 2007 and enacted in legislation in 2009 3 . They are also headline targets of the Europe 2020 strategy for smart, sustainable and inclusive growth.
標(biāo)簽： Preparatory Ecodesign Study
上傳時(shí)間： 2020-06-06
上傳用戶：shancjb
Resource allocation is an important issue in wireless communication networks. In recent decades, cognitive radio technology and cognitive radio-based networks have obtained more and more attention and have been well studied to improve spectrum utilization and to overcomethe problem of spectrum scarcity in future wireless com- munication systems. Many new challenges on resource allocation appear in cogni- tive radio-based networks. In this book, we focus on effective solutions to resource allocation in several important cognitive radio-based networks, including a cogni- tive radio-basedopportunisticspectrum access network, a cognitiveradio-basedcen- tralized network, a cognitive radio-based cellular network, a cognitive radio-based high-speed vehicle network, and a cognitive radio-based smart grid.
標(biāo)簽： Cognitive Networks Radio
上傳時(shí)間： 2020-06-07
上傳用戶：shancjb
This book is intended for researchers, teachers, and students willing to ex- plore conceptual bridges between the fields of Automatic Control and Power Electronics. The need to bring the two disciplines closer has been felt, for many years, both by Power Electronics specialists and by Automatic Control theorists, as a means of fruitful interaction between the two scientific com- munities. There have, certainly, been many steps given in that direction in the last decade as evidenced by the number of research articles in journals, special sessions in conferences, and summer courses throughout the world.
標(biāo)簽： Techniques Control Design
上傳時(shí)間： 2020-06-07
上傳用戶：shancjb
This book provides a comprehensive overview of the technology behind the pico-solar revolution and offers guidance on how to test and choose quality products. The book also discusses how pioneering companies and initiatives are overcoming challenges to reach scale in the market- place, from innovative distribution strategies to reach customers in rural India and Tanzania, to product development in Cambodia, product assembly in Mozambique and the introduction of ‘pay as you go’ technology in Kenya.
標(biāo)簽： Pico-solar Electric Systems
上傳時(shí)間： 2020-06-07
上傳用戶：shancjb
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