demultiplexing

Demultiplexing is the process of separating multiplexed signals into their individual components so that each component can be processed, routed, or analyzed independently. It is the inverse operation of multiplexing and is essential in many communication, computing, and data-processing systems.

In telecommunications and signal processing, demultiplexing is used to recover separate channels carried together. For example, in time-division multiplexing (TDM), a demultiplexer selects the appropriate time slot to retrieve each channel; in frequency-division multiplexing (FDM) or wavelength-division multiplexing (WDM), filters or wavelength-selective devices isolate the different frequency or wavelength bands. Code-division multiplexing (CDM) uses correlation techniques to extract the intended signal. Hardware demultiplexers and software-based demultiplexing are both common, depending on the application.

In computer networking, demultiplexing refers to routing an incoming data packet to the correct higher-layer protocol or connection. This involves using fields such as IP addresses, transport protocol identifiers, and port numbers to deliver data to the appropriate socket or service on a host.

In genomics and bioinformatics, demultiplexing assigns sequencing reads to their source samples when multiple samples are pooled together with unique barcodes. This step separates reads by barcode to reconstruct individual sample datasets.

Challenges in demultiplexing include cross-talk between channels, timing and synchronization errors, barcode collisions or misreads, and noise or distortion. Effective demultiplexing relies on accurate channel separation, robust detection methods, and proper calibration of the underlying multiplexing scheme.