[handover] Real handover algorithm
This implements the handover algorithm (and associated parameters)
as described in Chapter 8 of the book "Performance Enhancements in
a Frequency |Hopping GSM Network" by Thomas Toftegard Nielsen and Jeroen
Wigard.
The parameters such as averaging windows are configured in struct
gsm_network. We keep some state to trakc up to 10 neighbors as
they are being reported from the MS.
This has so far only been tested in a network with two BTS that
have each other as neighbor. Networks with morge neighbors might
encounter bugs.
diff --git a/openbsc/src/gsm_data.c b/openbsc/src/gsm_data.c
index 94ed91b..12f439b 100644
--- a/openbsc/src/gsm_data.c
+++ b/openbsc/src/gsm_data.c
@@ -210,6 +210,14 @@
net->T3113 = GSM_T3113_DEFAULT;
/* FIXME: initialize all other timers! */
+ /* default set of handover parameters */
+ net->handover.win_rxlev_avg = 10;
+ net->handover.win_rxqual_avg = 1;
+ net->handover.win_rxlev_avg_neigh = 10;
+ net->handover.pwr_interval = 6;
+ net->handover.pwr_hysteresis = 3;
+ net->handover.max_distance = 9999;
+
INIT_LLIST_HEAD(&net->trans_list);
INIT_LLIST_HEAD(&net->upqueue);
INIT_LLIST_HEAD(&net->bts_list);