half duplex communication

Transmission Modes refer to the direction of data transmission between two devices. For example, your cell phone is a full-duplex device because both parties can talk at once, but a walkie-talkie device is a half-duplex device because only one party can transmit at a time. Radio is an example of simple communication, where radio can only receive a signal and never transmit it. Half-duplex communications limit the exchange of data to one direction at a time, while full-duplex allows the sending and receiving of data at the same time.

Simplex Communication

In simplex transmission, communication between sender and receiver occurs only in one direction. Simplex is one-way communication in which the signals can travel only in one direction. The sender can only send, and the receiver can only receive or send. Radio Broadcasting, television broadcasting, computer-to-printer communication, and keyboard-to-computer connections are examples of simple communication.

Half-duplex communication

In half-duplex communication, one side can talk at a time, and the other side should listen. When one side has completely transmitted its data, the other can reply. Only one node can talk at a time. If both try to talk at the same time, a collision will occur on the network. So, both devices can transmit and receive the media but cannot do so simultaneously.

Half-duplex mode is used in legacy bus topologies and with Ethernet hubs. WLANs also operate in half-duplex. Half-duplex is used with contention-based access methods. This method of communication is not very efficient and requires more time to send/receive larger amounts of data. Older networks are mostly based in half-duplex mode due to the constraints of the network medium (coax cable) and hardware equipment (hubs), as shown in the figure below.

Full-duplex communication

Full-duplex is the type of communication in which both devices can transmit and receive on the media at the same time. The data link layer assumes that the media is available for transmission for both nodes at any time without any danger of collision. So, the transfer of data occurs much faster.

Ethernet switches operate in full-duplex mode by default but can operate in half-duplex if connecting to a device such as an Ethernet hub. The figure below illustrates full-duplex communication.

Today, all networks use switches instead of hubs and UTP Ethernet cabling instead of co-axial cabling, which allows full-duplex communication between all connected hosts. Both interconnected interfaces must operate using the