. . , b299), but only the first 288 bits are transmitted
and used. We can say the PICH frame consists of two parts: paging indicator and DTX.
In each PICH frame, the number of paging indicators transmitted is Np. Np can take on the following
values: 16, 36, 72, and 144. Which paging indicators to view, say Pq, is computed in the UE
with the help of the following variables: Paging indicator (PI) is calculated by the higher layers, the
System Frame Number (SFN) of the P-CCPCH radio frame that overlaps with the start of the PICH
frame, and lastly the number of paging indicators in the frame, Np. All of these values are used to
determine where in the frame to view the paging indicator bits. If the paging indicator was set to ???1,???
then the UE associated with this paging indicator should read the next frame of S-CCPCH; otherwise,
they should continue to sleep and wake up at the next scheduled time interval.
During idle mode operation, the UE will periodically wake up and demodulate the PICH bits. This
discontinuous reception is called a DRX cycle and takes on values of 5.12, 2.56, 1.28, 0.64, 0.32,
0.16, and 0.08 sec. Obviously, the larger the DRX cycle, the better your standby time will be for the
UE. However, the price to pay is the ability to control the time drifting of the locally generated timing
(time and frequency), as well as the potential of a service region change, if the UE is mobile.
Pages:
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631