Multiplexing

Multiplexing is a method used in communications to combine multiple signals into a single transmission medium, allowing more efficient use of bandwidth. The basic idea is to share a common channel among several data streams and then separate them again at the destination. The process is designed to prevent signals from interfering with one another while occupying the same physical medium.

Common multiplexing schemes include:

- Time-division multiplexing (TDM), which assigns distinct time slots in a fixed cycle to different signals so they take turns using the channel.

- Frequency-division multiplexing (FDM), which allocates separate frequency bands to each signal within the same channel.

- Wavelength-division multiplexing (WDM), the optical equivalent of FDM, which uses different light wavelengths to carry separate data streams in fiber optics.

- Code-division multiplexing (CDM) or code-division multiple access (CDMA), which assigns unique codes to signals that share the same frequency band, allowing simultaneous transmission and separation by code.

Demultiplexing is the complementary process performed at the receiver, extracting the original signals using the corresponding multiplexing scheme. Multiplexing is widely used in telecommunications, including telephone networks, satellite links, and fiber-optic backbones, as well as in data centers, broadcasting, and wireless systems.

Advantages of multiplexing include increased channel capacity and more efficient use of physical media. Potential challenges involve synchronization between transmitter and receiver, possible interference or cross-talk, added system complexity, and the need for guard intervals or bandwidth management to maintain signal integrity.