The first Third Generation Partnership Project (3GPP) Wideband Code Division Multiple Access (WCDMA) networks were launched during 2002. By the end of 2005 there were 100 open WCDMA networks and a total of over 150 operators having frequency licenses for WCDMA operation. Currently, the WCDMA networks are deployedinUniversalMobileTelecommunicationsSystem(UMTS)bandaround2GHz in Europe and Asia including Japan and Korea. WCDMA in America is deployed in the existing 850 and 1900 spectrum allocations while the new 3G band at 1700/2100 is expected to be available in the near future. 3GPP has defined the WCDMA operation also for several additional bands, which are expected to be taken into use during the coming years.
标签： HSDPAHSUPA Access Speed Radio UMTS High for
上传时间： 2020-05-27
上传用户：shancjb
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.
标签： Analog-Digital Precoding Hybrid
上传时间： 2020-05-27
上传用户：shancjb
Mobilenetworkoperatorswillmeetmanychallengesinthecomingyears.Itisexpectedthatthe numberofpeopleconnected,wirelineandwireless,willreachfivebillionby2015.Atthesame time, people use more wireless services and they expect similar user experience to what they can now get from fixed networks. Because of that we will see a hundred-fold increase in network traffic in the near future. At the same time markets are saturating and the revenue per bit is dropping.
标签： Self-Organising Networks LTE
上传时间： 2020-05-27
上传用户：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.
标签： Nanotechnology Applications
上传时间： 2020-05-31
上传用户：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.
标签： Wideband Signals Systems Ultra and
上传时间： 2020-06-01
上传用户：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.
标签： Performance High MEMS RF
上传时间： 2020-06-06
上传用户：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.
标签： MEMS-based Circuits Systems and
上传时间： 2020-06-06
上传用户：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.
标签： Preparatory Ecodesign Study
上传时间： 2020-06-06
上传用户：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.
上传时间： 2020-06-07
上传用户：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.
标签： Pico-solar Electric Systems
上传时间： 2020-06-07
上传用户：shancjb
