AWGN	Additive white Gaussian noise
CR	Cognitive radio
CRN	Cognitive radio networks
CSI	Channel state information
CSS	Cooperative spectrum sensing
DSA	Dynamic spectrum access
DT	Dynamic threshold
ED	Energy detection
EGC	Equal gain combining
IoT	Internet of Things
ISI	Inter-symbol interference
MIMO	Multiple-input multiple-output
MISO	Multiple-input single-output
NU	Noise uncertainty
OFDM	Orthogonal frequency division multiplexing
PDF	Probability density function
PU	Primary user
RF	Radio frequency
ROC	Receiver operating characteristic
SISO	Single-input single-output
SL	Square law
SLC	Square-law combining
SNR	Signal-to-noise ratio
SS	Spectrum sensing
STBC	Space–time block codes
SU	Secondary users