Wireless Technologies

Wireless Technologies

 

Abstract

 

                          This paper mainly introduces the development of mobile communication systems. In the first section, deals  the history of wireless communication and its applications. In the second section it focus on the wireless mobile communication and divide the development course of mobile communication into four generations. Then it shows the characteristics of each generation in detail. In the third section, the basic concept of CDMA by examples and discuss two famous standards of CDMA--IS 95 and CDMA2000. In the end, ideas about the future of the wireless mobile communication. the principles, advantages, challenges, and practical requirements of optical orthogonal frequency division multiplexing (OFDM)-based optical access are presented, with an emphasis on orthogonal frequency division multiple access (OFDMA) for application in next-generation passive optical networks (PON). General OFDM principles, including orthogonality, cyclic prefix use, frequency-domain equalization, and multiuser OFDMA are summarized, followed by an overview of various optical OFDM(A) transceiver architectures for next-generation PON. Functional requirements are outlined for high-speed digital signal processors (DSP) and data converters in OFDMA-PON. A techno-economic outlook for such a “software-defined,” DSP-based optical access platform is also provided.