Spectrum Handoff based on Imperfect Channel State Prediction Probabilities with Collision Reduction in Cognitive Radio Ad Hoc Networks

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. 2019 Oct 31;19(21):4741. doi: 10.3390/s19214741

Algorithm 1 Target channel selection.

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procedureTrue Prediction( $P r e d P r o b$ , $R e m P k t s$ )
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for $S U \in S y s t e m$ do /* existing SUs */
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$s o r t (a s c e n d)$ /* arrange SUs with respect to RemPkts in lowest to highest order*/
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end for
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for $C h$ $i = 1 : N_{c h}$ do
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$s o r t (d e c e n d)$ /* arrange all Channels with respect to prob of idleness in highest to lowest order*/
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end for
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for $j \leftarrow 1, l e n g t h (S U)$ do
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$C h_{j} \leftarrow S U_{j}$ /*Channel with jth highest prob of idleness is allotted to SU with jth shortest job*/
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if $C h_{j}$ $i s$ $s e n s e d i d l e$ then
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transmit $S U_{j}$ $u s i n g$ $C h_{j}$ /* contention free access as prediction is true*/
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remove $C h_{j}$ $f r o m$ $l i s t$ $o f$ $a v a i l a b l e$ $i d l e$ $c h a n n e l$
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else goto Procedure False Prediction
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end if
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end for
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end procedure
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$S U_{f p} =$ SUs unsuccessful in channel access due to false prediction
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$S U_{n} =$ new arriving SUs in the system
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$M_{n} =$ new arriving SUs in the system
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procedureFalse Prediction( $M_{n}$ , $S U_{n}$ , $S U_{f p}$ )
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$c o n t e n d e r s \leftarrow S U_{n} + S U_{f p}$
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$M_{n} \leftarrow l i s t o f a v a i l a b l e i d l e c h a n n e l s$
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begin contention for channel access/* All contenders contend for channel access in random access fashion*/
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if $c o l l i s i o n$ then
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wait until beginning of next $T_{c y c l e}$
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else
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transmit on channel accessed successfully during contention
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end if
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end procedure