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Table 2 Notations and definitions used for WF-MAC

From: Quality-of-service-aware weighted-fair medium access control protocol for coexisting cognitive radio networks



\(\mathcal {M}\)

Set of Licensed channels; { 1,2,3,…,m}

\(\mathcal {N}_{r}\)

Set of SUs of CRN r; { 1,2,3,…,n}


Set of traffic types


Priority value assigned to a specific traffic

H i

Status of channel i; { 0,1,2}


Time needed to sense a channel

σ s

Number of retransmissions for collision with SU

σ p

Number of retransmissions for PU appearance

\({\lambda ^{s}_{i}}\)

SU arrival rate over channel i

\({\lambda ^{p}_{i}}\)

PU arrival rate over channel i

\(\mathcal {E}\)

Channel availability vector

\(\mathcal {U}\)

Channel utility perception vector

\(\mathcal {O}\)

Channel usage outcome { o 1,o 2,o 3,o 4}

C W ρ

Contention window for packet priority type ρ