Which type of MAC protocol keeps receivers always active?

The type of MAC protocol that keeps receivers always active is characterized by the method of contention-based communication. In contention-based MAC protocols, such as Carrier Sense Multiple Access with Collision Detection (CSMA/CD) and Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA), all devices listen to the channel and vie for access to the medium whenever they have data to transmit.

This approach necessitates that receivers maintain an active listening state to detect when a sender is transmitting, which enables them to capture the data and respond appropriately. The continuous activity of the receivers ensures they are ready to process incoming messages, leading to lower latency in data transmission, as there are fewer delays associated with waking up from a sleep state or waiting for time slots.

In contrast, time-division MAC protocols allocate specific time slots to each transmitter, which allows the receivers to potentially enter low-power states during inactive slots. Frequency-division MAC protocols similarly allocate different frequency bands for different transmissions, which can also result in receivers being inactive during certain periods. Hybrid MAC protocols combine elements of both contention-based and schedule-based access, further introducing potential inactive periods for receivers.

Thus, the contention-based MAC protocols maintain constant activity for receivers, facilitating immediate data reception and ensuring effective communication in scenarios where