In telecommunications, duplex means "two-way" when referring to communications channels. Telecommunication is the extension of communication over a distance. ... A Communications channel (or channel for short), models the medium through which information is transmitted from a sender (or transmitter) to a receiver. ...

• A simplex channel is a one-way channel.
• A half-duplex channel is one that can carry information in both directions, but not at the same time.
• A full-duplex channel is a channel which can carry information in both directions at once.

These terms also apply to early PC sound cards, however almost all are now full-duplex. A simplex communication system is one where all signals flow in one direction. ... A sound card based on VIA Envy chip A sound card is a computer expansion card that can input and output sound under program control. ...

Where channel access methods are used for dividing forward and reverse communication channels on the same physical communications medium, they are known as duplexing methods, such as: In communications, a channel access method is used to share a communications channel or physical communications medium between multiple users. ...

• Time division duplex (TDD) is the application of time-division multiple access to separate outward and return signals
• Frequency division duplex (FDD) is the application of frequency-division multiple access to separate outward and return signals

Time Division Multiple Access (TDMA) is a technology for shared medium (usually radio) networks. ... FDMA, or frequency-division multiple access, is the oldest and most important of the three main ways for multiple radio transmitters to share the radio spectrum. ...

Usage in point-to-multipoint networks

In point to multipoint networks such as cellular networks, both TDD and FDD are used in communication between the base station and the mobile transmitter. A cellular radio network is a radio network made up of a number of radio cells (or just cells) each served by a fixed transmitter, normally known as a base station. ...

Time division duplex has a strong advantage in the case where the asymmetry of the uplink and downlink data speed is variable. As the amount of uplink data increases, more bandwidth can be allocated to that and as it shrinks it can be taken away. Another advantage is that the uplink and downlink radio paths are likely to be very similar in the case of a slow moving system. This means that techniques such as beam forming work well with TDD systems. Symmetry is a characteristic of geometrical shapes, equations and other objects; we say that such an object is symmetric with respect to a given operation if this operation, when applied to the object, does not appear to change it. ... This article deals with Uplink in the telecommunications terminology. ... 1. ...

Frequency division duplex is much stronger in the case of symmetric traffic. In this case TDD tends to waste bandwidth during switchover from transmit to receive, has greater inherent latency, and may require more complex, more power-hungry circuitry. // Analog For analog signals, bandwidth is the width, usually measured in hertz, of a frequency band f2 − f1. ... Latency is the time a message takes to traverse a system. ... There are many kinds of circuit An electric circuit interconnects electrical elements. ...