Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) is a protocol used in WiFi networks to reduce the chances of collision between multiple devices trying to communicate over the same medium. Here’s how CSMA/CA employs several mechanisms to achieve this:

• Carrier Sensing: Devices monitor the wireless channel for ongoing transmissions before initiating their own. If busy, they delay transmission.
• Interframe Spacing (IFS): Defines short pauses between frames to prioritize them based on urgency:
  • SIFS (Short Interframe Space): Used for high-priority ACK and control frames.
  • PIFS (PCF Interframe Space): Medium priority, utilized during contention-free periods managed by Access Points.
  • DIFS (DCF Interframe Space): Lowest priority, employed during regular network contention.
• Random Backoff Timer: After detecting a busy channel, devices set a random timer within a Contention Window to avoid simultaneous transmission attempts.
• RTS/CTS (Request to Send/Clear to Send): This optional protocol helps address the hidden node problem. An RTS frame is sent and, if clear, a CTS reply is received, informing nearby devices to pause transmissions temporarily.

Further Readings

• CSMA/CA
• MAC Frame