Nature is seldom kind. One of the most appealing uses for radio- telephone systems—communication with people on the move—must over- come radio transmission problems so difficult they challenge the imagina- tion. A microwave radio signal transmitted between a fixed base station and a moving vehicle in a typical urban environment exhibits extreme variations in both amplitude and apparent frequency.
标签： Communications Microwave Mobile
上传时间： 2020-05-28
上传用户：shancjb
Wireless is one of the most rapidly developing technologies in our time, with dazzling new products and services emerging on an almost daily basis. These developments present enormous challenges for communications engineers, as the demand for increased wireless capacity grows explosively. Indeed, the discipline of wireless communications presents many challenges to designers that arise as a result of the demanding nature of the physical medium and the complexities in the dynamics of the underlying network.
标签： Communications Wireless MIMO
上传时间： 2020-05-28
上传用户：shancjb
There are few technologies that have had a more profound effect on people’s lives than mobile communications. As recently as twenty years ago no one had a mobile phone, while today 1.4 billion men, women and children depend on them. This now exceeds the number of landline users, where it took the preceding one hundred years to reach the 1 billion mark. The ability to make mobile voice calls turns out to be the answer to a deeply felt need across different cultures who simply want to communicate.
标签： Communications Wireless Mobile and
上传时间： 2020-05-30
上传用户：shancjb
One of the very first books published on the social impact of the mobile phone was Timo Kopomaa’s The City in Your Pocket: Birth of the Mobile Information Society. The book, published in 2000, was based on research that Kopomaa had under- taken for Nokia and Sonera as part of his doctoral studies in the Centre for Urban and Regional Studies at the Helsinki University of Technology. The first line he writes in the book is peculiar: ‘Mobile communication is not a serious matter’. By this, we assume he is referring to a view of the world that would regard the mobile phone as little more than an unremarkable fact of everyday life – a simple play- thing for the young, or a productivity tool for the business executive and busy parent.
标签： Communications Wireless Mobile and
上传时间： 2020-05-30
上传用户：shancjb
Do you have a mobile phone? We think you probably do, one way or another. We would also guess that you might use it for many diff erent things in the course of your everyday life—as a telephone certainly, but also as an address book, as a clock or watch, as a camera, or now as a connection to your computer, email and the internet. Th ere will be a range of people you use it to contact (or not), and various strategies you use to take calls—or send texts, or take photos, or receive emails, or search online (or not, in diff erent situations). Th ere are also likely to be a range of social relation- ships in your life that your mobile phone helps to maintain—or disrupts, or inter- venes in, or makes possible, or complicates, or just plain helps to handle.
标签： Communications Introduction Mobile Media New An to
上传时间： 2020-05-30
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By definition, the term “mobile-radio communications” describes any radio communication link between two terminals of which one or both are in motion or halted at unspecified locations and of which one may actually be a fixed terminal such as a base station. This definition applies to both mobile-to-mobile and mobile-to-fixed radio communica- tion links. The mobile-to-mobile link could in fact consist of a mobile- to-fixed-to-mobile radio communication link.The term “mobile” applies to land vehicles, ships at sea, aircraft, and communications satellites. In tactical situations, mobile-radio systems may include any or all of these types of mobile terminals.
标签： Communications Engineering Mobile
上传时间： 2020-05-30
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Since the principle of multi-carrier code division multiple access (MC-CDMA) was simultaneously proposed by Khaled Fazel et al. and Nathan Yee et al. at the IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC) in the year 1993, multi-carrier spread spectrum (MC-SS) has rapidly become one of the most wide spread independent research topics on the field of mobile radio communications. Therefore, the International Workshop on Multi-Carrier Spread Spectrum (MC-SS) was initiated in the year 1997. Multi-carrier and spread spectrum systems with their generic air interface and adaptive technologies are considered as potential candidates to fulfill the requirements of next generation mobile communications systems.
标签： Multi-Carrier Spectrum Spread 2007
上传时间： 2020-05-31
上传用户：shancjb
Theartofcomputationofelectromagnetic(EM)problemshasgrownexponentially for three decades due to the availability of powerful computer resources. In spite of this, the EM community has suffered without a suitable text on the computational techniques commonly used in solving EM-related problems. Although there have been monographs on one particular technique or another, the monographs are written for the experts rather than students. Only a few texts cover the major techniques and dothatinamannersuitableforclassroomuse.Itseemsexpertsinthisareaarefamiliar with one or a few techniques but not many seem to be familiar with all the common techniques. This text attempts to fill that gap.
标签： Electromagnetics Techniques Numerical in
上传时间： 2020-05-31
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Ever since ancient times, people continuously have devised new techniques and technologies for communicating their ideas, needs, and desires to others. Thus, many forms of increasingly complex communication systems have appeared over the years. The basic motivations behind each new one were to improve the transmission fidelity so that fewer errors occur in the received message, to increase the transmission capacity of a communication link so that more infor- mation could be sent, or to increase the transmission distance between relay sta- tions so that messages can be sent farther without the need to restore the signal fidelity periodically along its path.
标签： Communications Essentials Optical
上传时间： 2020-05-31
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Recent decades have shown a tremendous expansion of the Internet. The number of connected terminals has increased by orders of magnitude, traffic has grown exponen- tially, coverage has become ubiquitous and worldwide, and today’s sophisticated Web 2.0 applications are increasingly providing services which hitherto have been the realm of telecommunications, such as Skype and video conferencing. This has even led to the thought that access to the Internet might one day be a universal right of every citizen. This evolution will accelerate in the coming decades.
标签： Networking Personal Networks Wireless
上传时间： 2020-05-31
上传用户：shancjb
