VollDuplex

Vollduplex, often written as full-duplex, is a mode of communication in which signals can be transmitted and received simultaneously over the same channel or link. This is in contrast to half-duplex, where transmission can occur in both directions but not at the same time, and simplex, where transmission is one-way.

In practice, vollduplex is achieved by separating the two directions of communication either through distinct physical paths (for example, a dedicated transmit and receive pair in copper or fiber) or by signaling techniques that partition the available bandwidth. Common approaches include frequency-division duplexing (FDD), which uses different frequency bands for upstream and downstream, and time-division duplexing (TDD), which shares a single band but alternates direction in time.

Applications are widespread in telephony and data networking. Traditional telephone systems use full-duplex speech channels, often supported by hybrid circuits that separate incoming and outgoing signals. Modern data networks typically operate in full-duplex mode on most switches and network interface cards, with Ethernet over copper or fiber links providing simultaneous two-way data transfer and eliminating collisions in switched configurations.

Advantages of vollduplex include higher effective throughput and better utilization of the link, reduced latency for two-way communication, and simpler contention handling in networks. Limitations involve the need for compatible hardware and cabling to support bidirectional transmission, potential interference and echo issues on some media, and higher system complexity or cost in older installations.

The term vollduplex is common in German-language documentation and literature as the equivalent of full-duplex.