Slot Cycle Index (SCI) in CDMA

In The CDMA System, Paging Channel ( the shared channel that all MS listen the paging channel for   system info like SID, NID, Zone, Time, PRL, PN etc), time is divided into "slots".  To conserve power, phones that are currently idle only "wake up" and listen for messages on the Paging Channel during their assigned slots.  The slot cycle index determines how often the phone's slot comes around.  If the slot cycle index is 0, the phone wakes up every 1.28 seconds.  If it's one, it wakes up every 2.56 seconds.  If it's two, it's every 5.12 seconds, and so on.  

The larger the setting of SCI, the more power is conserved, but the longer it takes to page the phone for an incoming call.  You can imagine that if it were set to 10.24 seconds, few callers would hang on the line long enough for you to answer your phone.

There are two settings that govern this.  One is the "preferred slot cycle index" in the phone, and can be set via service programming.  The other is the "maximum slot cycle index" set in the base station and broadcast in overhead messages on the Paging Channel.  The phone has to use whichever
number is smaller.

In Conclusion,

If this parameter is set to an excessively low value, the delay in call setup decreases, but the MS consumes more power and its standby time is shortened. If this parameter is set to an excessively high value, the delay in call setup increases, but the MS consumes less power.

Its value rage is 0~7.

The general default value is set to 1

Formula for SCI

Time period for MS to read its paging channel=16* 2 power SCI *80 ms.

Here 1 cycle = 16 slot = 1.28 sec

1 slot= 80 ms

If SCI =0

T=16 * 2 power 0 * 80 ms

= 1.28 sec

If SCI =1

T=16* 2 power 1*80 ms

=16*2*80 ms

=2560 ms

=2.56 sec.

Similarly ,

If SCI=2

T=5.12 Sec.