HO: New improved handover algorithm

The handover algorithm selects the best cell, tries to solve congestion
of cells and forces handover in case of bad radio link:

Handover shall ensure that the mobile station is always on the best cell
during a call. This results in best speech quality and allows a lower
TX level (up-link) to save battery and reduce interference.

Sometimes this is not desirable, especially if a cell with large coverage
becomes congested after handover. In this situation it makes sense to
balance the usage between cells to prevent congestion. If a cell is
congested, one or several mobile stations need to be handovered to a
different cell, even if that cell is not the best cell for these mobile
station.

In case that a mobile station needs to handover to prevent a loss of
radio link, it makes sense to handover it to a cell that is congested
afterwards. In this situation, a different mobile station on the congested
target cell can be handovered to a non-congested neighbor cell, to solve
or balance the congestion.

Because congestion of TCH/F and TCH/H is handled individually or bad
quality might require change from TCH/H to TCH/F, assignment instead
of handover might be used to change the channel within the same BTS. This
new algorithm handles both assigment and handover depending on the target
BTS.

1 files changed, 2 insertions, 1 deletions

diff --git a/src/libmsc/vty_interface_layer3.c b/src/libmsc/vty_interface_layer3.c
index 163e58e32..9e7a948da 100644
--- a/src/libmsc/vty_interface_layer3.c
+++ b/src/libmsc/vty_interface_layer3.c
@@ -631,7 +631,8 @@ DEFUN(ena_subscr_handover,
 	}
 
 	/* now start the handover */
-	ret = bsc_handover_start(conn->lchan, bts);
+	ret = bsc_handover_start(conn->lchan, bts,
+		(conn->lchan->type != GSM_LCHAN_TCH_H));
 	if (ret != 0) {
 		vty_out(vty, "%% Handover failed with errno %d.%s",
 			ret, VTY_NEWLINE);