Multiplexed

Multiplexed describes signals, streams, or content that have been combined into a single medium for transmission or storage, with the ability for the original components to be separated later by a demultiplexer. Multiplexing increases capacity by sharing a channel among multiple sources.

The major multiplexing techniques are time-division multiplexing (TDM), which assigns distinct time slots to each signal; frequency-division multiplexing (FDM), which places signals in separate frequency bands; and, in optical networks, wavelength-division multiplexing (WDM), which uses multiple wavelengths on a single fiber. Code-division multiplexing (CDM) and space-division multiplexing (SDM) are alternative approaches that distinguish signals by code or spatial paths. Modern systems often combine methods in layered or hybrid schemes.

Applications include telecommunications, broadcasting, and data networks. TDM has historically supported telephone traffic; FDM is used for traditional radio and cable channels; WDM enables many channels on a single optical fiber. In digital media, multiple audio, video, and data streams are multiplexed into a single transport stream for delivery, such as MPEG-based formats and digital broadcasting standards.

Key considerations for multiplexed systems include synchronization, timing alignment, and overhead from multiplexing itself. Demultiplexing at the receiver restores the individual streams for processing. Multiplexing remains a foundational technique for efficient use of bandwidth across diverse technologies.