• PHP初级教程

    PHP初级教程,简单快速的入门教程。PHP 是一种创建动态交互性站点的强有力的服务器端脚本语言。 PHP 是免费的,并且使用广泛。对于像微软 ASP 这样的竞争者来说,PHP 无疑是另一种高效率的选项。

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    2015-08-15
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  • Cognitive.and.Cooperative.Broadband.Technologies

    Wireless communications continue to attract the attention of both the research community and industry. In the period since the book was published, significant research and industry activities have brought the fourth generation of wireless communications systems closer to implementation and standardization. Important results for this book, covering the components of common air interface, are in the area of space time coding and multicarrier modulation, especially OFDM. Within OFDM technology, for the application in high mobility environments, the most important problems are channel estimation, synchronization, and problems related to large peak-to-average power ratio. For this reason some new material has been added to Chapters 4 and 7. For the same reason, Chapter 9 is completely new and covers linear precoding in MIMO channels based on complex optimization theory. The third important component of common air interface is media access control. This includes problems of adjacent cell interference, flexible spectra sharing and cooperation between the nodes in ad hoc networks so new material based on game theory modelling is introduced in Chapter 16. This also includes material on cooperative diversity transmission, introduced in Chapter 11, which is an emerging technology that has attracted a lot of interest lately. In addition to this, the problem of coexistence of different wireless networks is also becoming more and more important and solutions other than frequency planning and standardizations are needed. For this reason Chapter 12 is completely replaced and now presents the latest schemes for interference suppression in ultra wide band (UWB) cognitive systems, like advanced personal area networks (PAN) and discusses its performance. The schemes can be used significantly to improve performance of UWB systems, e.g. high speed Bluetooth, in the presence of interference from mobile communication systems such as GSM and WCDMA. It is also effective in the presence of WLAN systems which are nowadays based on OFDMA technology (e.g. IEEE802.11, 16e, 20) or military communications where the interference is generated by intentional jamming. The chapter also discusses the effectiveness of the scheme to suppress MC CDMA, which is a candidate technology for 4G mobile communications. Chapter 13 is significantly modified to include more details on positioning. This is the result of anticipation that this technique will be gaining more and more space in advanced wireless communications. This is also supported by activities within the Galileo program in Europe. In order to keep the book within acceptable limits, a part of the material from the previous edition has been left out. Most of the material omitted is from the sections on software radio. It is believed that this choice will make the content of the book more compact. 1 Fundamentals. 2 Adaptive coding. 3 Adaptive and Reconfigurable Modulation 4 Space Time Coding. 5 Multiuser communication. . 6 Channel estimation and equalization. 7 Orthogonal Frequency Division Multiplexing and MC CDMA. 8 Ultra Wide Band Radio. 9 Antenna Array Signal Processing. 10 Cognitive Radio. 11 Wireless Networks. 12. Cognitive UWB Communications. 13. Positioning in Wireless Networks. 14 Channel Modeling and Measurements for 4G. 15 Adaptive 4G Networks. 16 Cognitive Networks and Game Theory.

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