multiplexning

Multiplexning is a method for sending two or more signals over a single transmission path or channel by combining them into one signal that is transmitted and later separated into the original streams at the destination. The technique increases the capacity of a link without additional physical media and is widely used in communications, broadcasting, and data networks. A device called a multiplexer performs the combining, and a demultiplexer retrieves the individual signals at the receiving end.

Common forms of multiplexing include time-division multiplexing (TDM), which assigns discrete time slots to each signal; frequency-division multiplexing (FDM), in which each signal modulates a separate carrier frequency; wavelength-division multiplexing (WDM), used in optical networks where signals occupy different light wavelengths; code-division multiplexing (CDM), which spreads signals with distinctive codes; and space-division multiplexing (SDM), which uses multiple spatial paths such as fiber cores or antenna beams. Each method has characteristics related to bandwidth utilization, latency, and interference management.

Operation and components: A multiplexer combines inputs, and a demultiplexer separates them. In digital systems, synchronization and clocking align time slots; guard bands or codes minimize cross-talk; and error detection or correction schemes improve reliability. Standards and interfaces govern how signals are formatted and transmitted, enabling interoperability across equipment and networks.

Applications: Multiplexing is fundamental to modern communications, including telephone networks, broadcasting, satellite and cable systems, and optical and wireless data networks. By efficiently sharing a single medium, multiplexing enables higher aggregate throughput and flexibility in network design, while balancing complexity and cost.