Disadvantage: Complex transmitters and receivers. They must be wide-band, which means they are more expensive and possibly less reliable.
In analog transmission, signals are commonly multiplexed using frequency-division multiplexing (FDM)
Downward multiplexing refers to distributing a single signal across multiple channels.
Multiplexing techniques vary widely based on what is being multiplexed. Modern telecommunications use a very wide array of techniques including: TDM - examples: TDMA, T-carrier FDM - examples: DWDM Spatial - example: MIMO Code division - examples: CDMA Phase or polarization division - cable/satellite TV Statistcal - examples: packet mode (STS), FHSS etc etc. This is far from a complete list. I think the question needs to be more specific.
SONET uses an inverse multiplexing technique called virtual concatenation. SONET, which is the standard used in the United States and most of Europe, stands for Synchronous Optical Network.
TDM
disadvantages of wavelenth division multiplexing
Frequency-division multiplexing, wavelength-division multiplexing, and time-division multiplexing.
Frequency-division multiplexing and wavelength-division multiplexing
What is multiplexing and its diagram
what is function of amplitude division multiplexing
application of multiplexing in data communication
In analog transmission, signals are commonly multiplexed using frequency-division multiplexing (FDM)
Downward multiplexing refers to distributing a single signal across multiple channels.
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.
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.
Multiplexing techniques vary widely based on what is being multiplexed. Modern telecommunications use a very wide array of techniques including: TDM - examples: TDMA, T-carrier FDM - examples: DWDM Spatial - example: MIMO Code division - examples: CDMA Phase or polarization division - cable/satellite TV Statistcal - examples: packet mode (STS), FHSS etc etc. This is far from a complete list. I think the question needs to be more specific.
nothing