  Cognitive radio allows unlicensed users to access licensed frequency bands
through dynamic spectrum access so as to reduce spectrum scarcity. This
requires intelligent spectrum sensing techniques. This paper investigates the
use of cyclo-stationary detector and performance evaluation for Digital Video
Broadcast-Terrestrial (DVB-T) signals. Generally, DVB-T is specified in IEEE
802.22 standard in VHF and UHF TV broadcasting spectrum. Simulations results
show that implementing co-operative spectrum sensing help in better utilization
of resources. The paper further proposes to find number of optimal users in a
scenario to optimize the detection probability and makes use of the particle
swarm optimization (PSO) technique to find an optimum value of threshold.
