▁the ▁distance ▁increases ▁from ▁the ▁T ET RA ▁base ▁station . ▁ ▁From ▁this ▁illustr ation , ▁these ▁S RT ▁and ▁F RT ▁trigger ing ▁points ▁are ▁associated ▁to ▁the ▁decay ing ▁radio ▁signal ▁strength ▁of ▁the ▁respective ▁cell ▁carri ers . ▁The ▁th resh olds ▁are ▁situated ▁so ▁that ▁the ▁cell ▁res e lection ▁procedures ▁occur ▁on ▁time ▁and ▁ass ure ▁communication ▁continu ity ▁for ▁on - going ▁communication ▁calls . ▁ ▁Initial ▁cell ▁selection ▁▁ ▁The ▁next ▁diagram ▁illustr ates ▁where ▁a ▁given ▁T ET RA ▁radio ▁cell ▁initial ▁selection . ▁The ▁initial ▁cell ▁selection ▁is ▁performed ▁by ▁procedures ▁located ▁in ▁the ▁M LE ▁and ▁in ▁the ▁MAC . ▁When ▁the ▁cell ▁selection ▁is ▁made , ▁and ▁possible ▁registration ▁is ▁performed , ▁the ▁mobile ▁station ▁( MS ) ▁is ▁said ▁to ▁be ▁attached ▁to ▁the ▁cell . ▁The ▁mobile ▁is ▁allowed ▁to ▁initially ▁select ▁any ▁suitable ▁cell ▁that ▁has ▁a ▁positive ▁C 1 ▁value ; ▁i . e ., ▁the ▁received ▁signal ▁level ▁is ▁greater ▁than ▁the ▁minimum ▁receive ▁level ▁for ▁access ▁parameter . ▁ ▁The ▁initial ▁cell ▁selection ▁procedure ▁shall ▁ensure ▁that ▁the ▁MS ▁selects ▁a ▁cell ▁in ▁which ▁it ▁can ▁reli ably ▁decode ▁down link ▁data ▁( i . e ., ▁on ▁a ▁main ▁control ▁channel / MC CH ), ▁and ▁which ▁has ▁a ▁high ▁probability ▁of ▁u pl ink ▁communication . ▁The ▁minimum ▁conditions ▁that ▁shall ▁have ▁to ▁be ▁met ▁are ▁that ▁C 1 ▁> ▁ 0 . ▁Access ▁to ▁the ▁network ▁shall ▁be ▁conditional ▁on ▁the ▁successful