Question

What is reactive handoff?

(a) xG user performs sensing and sensing is performed before the triggering event

(b) xG user performs sensing and sensing is performed after triggering event

(c) Primary user performs sensing and sensing is performed before the triggering event

(d) Primary user performs sensing and sensing is performed after triggering event

This question was addressed to me in an interview for internship.

This intriguing question originated from Next Generation Wireless Network topic in division Next Generation Wireless Network of Cognitive Radio

Answer 1

Correct answer is (b) xG user performs sensing and sensing is performed after triggering event

The explanation: In the reactive handoff, the xG user begins to sense for available spectrum bands for handoff only after the triggering event. The advantage of this method is that the best available spectrum band is selected. However this method exhibits longer handoff latency.