Application: USE YOUR BROWSER "BACK" BUTTON TO RETURN © 1999 DR. ERNEST SIMO - SPACE2000 
Example: The mobile first uses its hashing function to calculate a uniformly distri-buted random variable between zero and 2047. This number is PGSLOT. As-sume that PGSLOT equals 6. The mobile now specifies its preferred slot cycle. The minimum slot cycle is 1.28 seconds (16 slots) and the maximum slot cycle is 2048 slots of 80 msec each or 163.84 seconds (2.73 minutes). Suppose the mobile selects a slot cycle time equal to the minimum time of 1.28 seconds. Then the slots assigned to the mobile are defined by the equa-tion [ {t/4} -PGSLOT ] mod (16xT) =0 (1) where t is the system time in frames, {t/4} denotes the largest integer less than or equal to t/4 , T is the slot cycle time expressed in units of 1.28 sec., given by 2i, where i is the slot cycle index. In our example, T equals 1, which corresponds to the slot cycle index i equal to zero. Substituting values into Eq. (1) yields the slots assigned to the mobile as [ {t/4} -6 ] mod 16 =0 (2) With the 20 msec frames used in IS-95, {t/4} is actually a slot number. The slots in the paging channel are numbered zero to 2047, and then the number-ing repeats. When t equals 24 frames (6 slots), Eq. (2) is zero signifying that the first slot to be monitored is slot number 6, which equals PGSLOT. The next time that Eq. (2) is satisfied will be when {t/4} equals 22, or in slot number 22. Eq. (2) will thereafter be satisfied when the slot numbers equal 6+16m, where m is an integer from zero to 127. With m equal to 127, the assigned slot number equals 2038. The next slot assigned after slot 2038 will be slot number 6 again. USE YOUR BROWSER "BACK" BUTTON TO RETURN © 1999 DR. ERNEST SIMO - SPACE2000 |
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