In telecommunications and computer networking, CTS or “Clear to Send” is a control signal used in the RTS/CTS (Request to Send/Clear to Send) handshake. Here’s a brief overview of CTS:
Purpose: The main purpose of the RTS/CTS mechanism is to mitigate the Hidden Node Problem in wireless networks and to manage access to the shared communication medium, ensuring that only one device transmits data at a given time.
Functionality:
- A device wishing to send data first transmits an RTS (Request to Send) packet.
- If the receiving device or access point (in a Wi-Fi context) hears the RTS and determines that it’s okay for the sender to transmit its data, it replies with a CTS (Clear to Send) packet.
- Upon receiving the CTS, the sender knows it’s clear to begin data transmission without interference from other devices.
Benefits:
- Collision Avoidance: By ensuring that only one device transmits at a time, RTS/CTS helps avoid data collisions in the wireless medium.
- Efficient Use of Bandwidth: With fewer collisions, less bandwidth is wasted on retransmissions.
- Hidden Node Problem: In wireless networks, two devices might be in range of a common access point but not in range of each other. Using RTS/CTS ensures that if one device is transmitting, another hidden device will know not to transmit at the same time, reducing interference.
Usage: While RTS/CTS can provide several benefits, especially in busy networks, it introduces additional overhead because of the RTS and CTS packets. As a result, it’s not always used by default and is typically configurable depending on the network’s needs.
The CTS signal, in its essence, is an acknowledgment signal given by a receiving entity, indicating it is ready to accept data from a transmitting entity.