One traditional view of how wireless networks evolve is of a continuous, inevitable progres- sion to higher link speeds, combined with greater mobility over wider areas. This standpoint certainly captures the development from first and second generation cellular systems focused on voice support, and the early short-range wireless data networks, through to today’s 3G cellular and mobile broadband systems; there is every confidence that the trend will continue some way into the future.
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Mobile communication devices like smart phones or tablet PCs enable us to consume information at every location and at every time. The rapid development of new applications and new services and the demand to access data in real time create an increasing throughput demand. The data have to be transmitted reliably to ensure the desired quality of service. Furthermore, an improved utilization of the bandwidth is desired to reduce the cost of transmission.
標簽： Architectures Processing Baseband Signal for
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Traditional modulation methods adopted by space agencies for transmit- ting telecommand and telemetry data have incorporated subcarriers as a sim- ple means of separating different data types as well ensuring no overlap between the radio frequency (RF) carrier and the modulated data’s frequency spectra.
標簽： Bandwidth-Efficient Modulation Digital
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Since the telephone was invented in the late nineteenth century, there has been a steady development of telephone services, and the number of subscribers has con- tinuously increased. One of the most revolutionary developments in telephone serv- ice in the late twentieth century was the introduction of the cellular variety of mobile phone services.
標簽： Engineering Capacity Systems CDMA
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According to the statistics of the Federal Communications Commission (FCC), temporal and geographical variations in the utilization of the as- signed spectrum range from 15% to 85%. The limited available radio spec- trum and the inefficiency in spectrum usage necessitate a new commu- nication paradigm to exploit the existing spectrum dynamically.
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Cognitive radio has emerged as a promising technology for maximizing the utiliza- tion of the limited radio bandwidth while accommodating the increasing amount of services and applications in wireless networks. A cognitive radio (CR) transceiver is able to adapt to the dynamic radio environment and the network parameters to maximize the utilization of the limited radio resources while providing flexibility in wireless access. The key features of a CR transceiver are awareness of the radio envi- ronment (in terms of spectrum usage, power spectral density of transmitted/received signals, wireless protocol signaling) and intelligence.
標簽： Cognitive Wireless Network
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The term economics is generally understood to mean sound management. This is associated with openness, good faith, accurate figures and integrity in company accounts, with transparency ensured through satisfactory standards of good practice in relation to investors and the clients who have placed their trust in an organization’s managers.
標簽： Communication Networks Economy
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Many times I have been asked to explain “ briefl y ” how SDH, SONET, and the OTN “ exactly ” work. The questions came mainly from new colleagues, stu- dents, and users of these technologies, personally or via the usenet newsgroup comp.dcom.sdh - sonet. I could have referred them to the standards documents, but to provide a more consistent and clear answer I decided to write this pocket guide. The objective of this book is that it can be used both as an introduction as well as a reference guide to these technologies and their spe- cifi c standards documents.
標簽： Generation Transport Optical ComSoc Guide
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This chapter introduces concepts on cooperating objects and wireless sensor net- works that will be used in the following chapters. It also introduces the Embedded WiSeNts Coordination Action. Finally, it presents an overview of the book and the relations between the following chapters.
標簽： Cooperating Embedded Systems
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Mobile communication has gained significant importance in today’s society. As of 2010, the number of mobile phone subscribers has surpassed 5 billion [ABI10], and the global annual mobile revenue is soon expected to top $1 trillion [Inf10]. While these numbers appear promising for mobile operators at first sight, the major game-changer that has come up recently is the fact that the market is more and more driven by the demand for mobile data traffic [Cis10].
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