Cell Load Sharing

–The purpose of the Cell Load Sharing feature is to distribute some of a cells traffic load to surrounding cells during peaks in traffic.

−This is achieved by moving established connections to neighboring cells that have idle resources.

−Cell Load Sharing increases the number of handovers in the part of the network where the traffic load is unevenly distributed

-Cell Load Sharing is activated on the BSC level via parameter LSSTATE (Active/Inactive) and activated on cell level via parameter CLSSTATE (Active/Inactive)

–The traffic load (amount of idle full rate TCHs) on each cell is examined by the BSC every CLS time Interval defined by a parameter CLSTIMEINTERVAL (default=100msec)

−If the percentage of idle full rate traffic channels is ≤ parameter CLSLEVEL, then this cell will try to get rid of some traffic by initiating cell load sharing handovers to neighbors.

−For a neighbor cell to accept HOs due to cell load sharing then parameter HOCLSACC should be set to “ON”

−The traffic load on the neighbor cells should also be examined so handovers due to cell load sharing will only be done to neighbors having enough idle full rate TCHs ( percentage of idle full rate TCHs > CLSACC inorder to accept HO due to CLS)

–CLS evaluation is performed after normal locating evaluation for neighboring cells.

–The normal Basic ranking evaluation was done as follows:

Rankservingcell = SS_DLservingcell

Rankneighbor= SS_DLneighbor – OFFSETneighbor – HYSTneighbor

−Now when the % idle full rate TCHs < CLSLEVEL, then the HYST for neighbors will be recalculated with reduced values based on parameter RHYST

−Rankneighbor= SS_DLneighbor – OFFSETneighbor – HYSTnew neighbor

Where HYSTnew neighbor = HYSTneighbor [1-2 (RHYST/100)]