Code Division Multiple Access

Code Division Multiple Access

Abstract

This report discusses the application of CDMA technology to communicate input port sand output ports inside a switch. The emphasis is on high-speed optical applications. The report discusses 1)History 2)How signal is it generated,3)How/why does it travel,4)How is it modulated,5)How can it be coded/decoded, how can it be shared among several transmitters6)CDMA:basic principles,7)Advantages/disadvantages communications. At least 9 modes should be used for error-free transmission at 1 Gbit/s for the laser we investigated in this work.. The optic code division multiple access (OCDMA) technique, where different users are assigned different “signature codes”, is a promising candidate for next-generation broadband Access networks. As it allows many users to share the same transmission channel, it has unique advantages inherently allowing dynamic allocation of bandwidth, protocol transparency, and a fully asynchronous operation mode with low latency that is suitable for the burst traffic environment. It also offers robust signal security, permitting quality of service guarantees to be managed at the physical layer by assigning different weight codes to different users, and simplified management of large numbers of users by only requiring minimal network control and the coding operation in CDMA can be roughly optical source should have a relatively high speed for temporal spreading and broadband optical spectra for spectral coding, as well as a high time-bandwidth (TB) product. Access, a digital cellular technology that uses spread-spectrum techniques. Unlike competing systems, such as GSM, that use TDMA. CDMA does not assign a specific frequency to each user. Instead, every channel uses the full available spectrum. Individual conversations are encoded with a pseudo-random digital sequence. CDMA consistently provides better capacity for voice and data communications than other commercial mobile technologies, allowing more subscribers to connect at any given time, and it is the common platform on which 3G technologies are built. Once the information became public, Qualcomm claimed patents on the technology and became the first to commercialize it.