Which protocol helps mitigate hidden node problems by coordinating transmissions?

Which protocol helps mitigate hidden node problems by coordinating transmissions?

• A. DHCP.
• B. ARP.
• C. RTS/CTS.
• D. DNS.

Answer: (C)

Hidden node problems arise in wireless networks when two stations can reach the same receiver but cannot hear each other, so they may transmit at the same time and cause a collision at the destination. RTS/CTS, a handshake used in many 802.11 networks, coordinates access to the wireless medium to prevent that scenario. A station wanting to send first sends a Request to Send, asking for permission. If the receiver agrees, it replies with a Clear to Send. Other devices that hear the CTS know the channel will be used and defer their own transmissions for the duration of the upcoming data transfer. This helps even stations that didn’t hear the original RTS but can hear the CTS, effectively reducing collisions caused by hidden terminals. Of course, this adds some signaling overhead, so RTS/CTS is typically used for larger frames or in networks where hidden-node problems are likely. DHCP, ARP, and DNS serve different roles—allocating IP addresses, mapping IP to MAC addresses, and translating hostnames to IPs, respectively—and do not address medium access coordination.