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Multiplexing is the process of combining multiple signals over one media line. There are several types of multiplexing: frequency division, time division, and wavelength division.
WDM (wavelength division multiplexing)
Andrea Borella has written: 'Wavelength division multiple access optical networks' -- subject(s): Multiplexing, Wave length, Congresses, Wavelength division multiplexing, Light, Optical communications
AM radio broadcasting uses frequency division multiplexing to allocate different frequencies to different radio stations. Cable television systems use frequency division multiplexing to transmit multiple channels simultaneously over a single cable. Cell phone networks use frequency division multiplexing to separate different users' calls on the same frequency band.
GSM - Global System for Mobile Communications (2G) uses TDMA - Time Division Multiple Access Multiplexing.
Currently the mobiles use GSM(Geo Synchronous Mobiles ) and CDMA(Code Division Multiple Accesss) techniques. GSM inturn uses TDMA(Time Division Multiplexing) or FDMA(Frequency Division Multiplexing) or sometimes both to fit in the required criteria.
Time Division Multiplexing and Frequency Division Multiplexing. Allows multiple data channels across a single medium by separating the data streams onto different frequencies (FDM), or by sending one stream, waiting, then sending the other stream (TDM).
DWDM (Dense Wavelength Division Multiplexing)
The bits associated with synchronization and framing increase the processing overhead in asynchronous time division multiplexing. These bits are necessary for maintaining the timing and alignment of data streams from multiple sources within the system.
The basic difference between fdm and fdma is that fdm is used in wired system where as fdma is used in wireless communication.
multiplexing refeers to the transmission of different signals in the same channel simultaneously. There are many forms of multiplexing that can be used, including frequency division multiplexing(FDM) where individual signals are transmitted over adjacent , non overlapping frequency bands. they are transmitted in parallel and simultaneously in time. In time division multiplexing(TDM) each signal is allowd to use the whole bandwidth for a certain period of time. Multiplexing is needed so that the available channel can be used efficiently and also to save costs. There is too much to know about multiplexing, here is just a short overview. One thing that one has to know is multiple access.
Downward multiplexing refers to distributing a single signal across multiple channels.