Cell Reselection Process

Cell reselection for cells in same location area

If the C2 value of the target cell is higher than that of the serving cell and last for longer than 5 seconds, a cell reselection process will be performed and the MS tunes to the new cell.

Cell reselection for cells in different location areas

If the C2 value of the target cell is higher than that of the serving cell by at least the value of CRH and last for longer than 5 seconds, a location updating process and the cell reselection process will be performed.

Cell reselections caused by C2 have a time interval of 15 seconds

If current serving cell is prohibited, or down link fails, or C1 is less than 0 continuously for 5s, cell reselection will also be triggered.

MS starts a cell reselection if the access times exceed the  MAX retrans . 

 

 

C2=C1+CRO-TO*H(PT-T)

When PT is not equal to 31:

C2=C1-CRO

When PT is equal to 31.

Wherein:

1. Function H(x)=0, when x<0; H(x)=1, when x>0.

2. T is a timer with initial value 0. When a certain cell becomes of one of the six neighbor cells with highest signal level, T corresponding to this cell begins to count with accuracy of one TDMA frame (about 4.62ms). When it is out of the six strongest neighbor cells, the corresponding timer is reset.

3. CRO is used for manually correct the cell reselection parameter C2.

4. The function of TO is to reduce the value of C2 from the time when timer begins to count to the time when the value of timer reaches the stipulated PENALTY_TIME.

5. PT is the time TO acts on C2. But PT=31 is reserved as the symbol to change the CRO’s effect on C2.