Wireless Oom

The paging occasion
is
the SFN of the frame of which the UE must monitor the PICH to see whether a paging message is being sent to the UE.
For FDD,
paging occasion (SFN) = (IMSI div K) mod (DRX cycle length) + n* DRX cycle length
where n=0, 1, 2, up to a maximu such that SFN is valid [...]