neels has uploaded this change for review. (
https://gerrit.osmocom.org/c/osmo-bsc/+/21971 )
Change subject: hodec2: code dup / cosmetics
......................................................................
hodec2: code dup / cosmetics
In handover_decision_2.c, instead of repeating a similar loop four
times, put that loop in a function and parameterize it.
Prepare for a fix of two problems in handover decision 2, see
I2704899c85c35dfd4eba43468452483f40016ca2.
Change-Id: I7c32d08e490a88a7f044b0a71dc4b07d748dd572
---
M src/osmo-bsc/handover_decision_2.c
1 file changed, 133 insertions(+), 194 deletions(-)
git pull ssh://gerrit.osmocom.org:29418/osmo-bsc refs/changes/71/21971/1
diff --git a/src/osmo-bsc/handover_decision_2.c
b/src/osmo-bsc/handover_decision_2.c
index 477f1eb..7854f09 100644
--- a/src/osmo-bsc/handover_decision_2.c
+++ b/src/osmo-bsc/handover_decision_2.c
@@ -24,6 +24,7 @@
#include <stdbool.h>
#include <errno.h>
+#include <limits.h>
#include <osmocom/bsc/debug.h>
#include <osmocom/bsc/gsm_data.h>
@@ -1379,10 +1380,22 @@
return count;
}
+static bool is_intra_cell(const struct ho_candidate *c)
+{
+ return c->bts && (c->lchan->ts->trx->bts == c->bts);
+}
+
+static bool is_upgrade_to_tchf(const struct ho_candidate *c, uint8_t
for_requirement)
+{
+ return c->lchan
+ && (c->lchan->type == GSM_LCHAN_TCH_H)
+ && ((c->requirements & for_requirement) & (REQUIREMENT_B_TCHF |
REQUIREMENT_C_TCHF));
+}
+
/* Given two candidates, pick the one that should rather be moved during
handover.
* Return the better candidate in out-parameters best_cand and best_avg_db.
*/
-static void pick_better_lchan_to_move(bool want_highest_db,
+static bool pick_better_lchan_to_move(bool want_highest_db,
struct ho_candidate **best_cand_p,
unsigned int *best_avg_db_p,
struct ho_candidate *other_cand, unsigned
int other_avg_db)
{
@@ -1400,7 +1413,7 @@
/* If both are dynamic, prefer one that completely (or to a
higher degree) frees its timeslot. */
if (lchan_is_on_dynamic_ts((*best_cand_p)->lchan)
&& ts_usage_count((*best_cand_p)->lchan->ts) <
ts_usage_count(other_cand->lchan->ts))
- return;
+ return false;
/* If both equally satisfy these preferences, it does not
matter which one is picked.
* Give slight preference to moving later dyn TS, so that a
free dyn TS may group with following static
* PDCH, though this depends on how the user configured the TS
-- not harmful to do so anyway. */
@@ -1408,11 +1421,76 @@
}
/* keep the same candidate. */
- return;
+ return false;
return_other:
*best_cand_p = other_cand;
*best_avg_db_p = other_avg_db;
+ return true;
+}
+
+static struct ho_candidate *pick_best_candidate(int *applied_afs_bias,
+ struct ho_candidate *clist, int
clist_len,
+ bool want_highest_db,
+ bool
omit_intra_cell_upgrade_to_tchf,
+ bool
only_intra_cell_upgrade_to_tchf,
+ uint8_t for_requirement)
+{
+ struct ho_candidate *result = NULL;
+ unsigned int result_avg_rxlev;
+ int result_afs_bias = 0;
+ int i;
+
+ if (applied_afs_bias)
+ *applied_afs_bias = 0;
+
+ result_avg_rxlev = want_highest_db ? 0 : INT_MAX;
+
+ for (i = 0; i < clist_len; i++) {
+ struct ho_candidate *c = &clist[i];
+ bool intra_cell;
+ bool upgrade_to_tch_f;
+ int avg_rxlev;
+ int afs_bias;
+
+ /* For multiple passes of congestion resolution, already
handovered candidates are marked by lchan =
+ * NULL. (though at the time of writing, multiple passes of
congestion resolution are DISABLED.) */
+ if (!c->lchan)
+ continue;
+
+ /* Omit remote BSS */
+ if (!c->bts)
+ continue;
+
+ if (!(c->requirements & for_requirement))
+ continue;
+
+ intra_cell = is_intra_cell(c);
+ upgrade_to_tch_f = is_upgrade_to_tchf(c, for_requirement);
+
+ if (only_intra_cell_upgrade_to_tchf
+ && !(intra_cell && upgrade_to_tch_f))
+ continue;
+ if (omit_intra_cell_upgrade_to_tchf
+ && (intra_cell && upgrade_to_tch_f))
+ continue;
+
+ avg_rxlev = c->avg;
+
+ /* improve AHS */
+ if (upgrade_to_tch_f)
+ afs_bias = ho_get_hodec2_afs_bias_rxlev(c->bts->ho);
+ else
+ afs_bias = 0;
+ avg_rxlev += afs_bias;
+
+ if (pick_better_lchan_to_move(want_highest_db, &result,
&result_avg_rxlev, c, avg_rxlev))
+ result_afs_bias = afs_bias;
+ }
+
+ if (applied_afs_bias)
+ *applied_afs_bias = result_afs_bias;
+ return result;
}
/*
@@ -1472,10 +1550,7 @@
int i, j;
struct ho_candidate *clist;
unsigned int candidates;
- struct ho_candidate *best_cand = NULL, *worst_cand = NULL;
- struct gsm_lchan *delete_lchan = NULL;
- unsigned int best_avg_db, worst_avg_db;
- int avg;
+ struct ho_candidate *best_cand = NULL;
int rc = 0;
int any_ho = 0;
int is_improved = 0;
@@ -1571,55 +1646,19 @@
#if 0
next_b1:
#endif
- /* select best candidate that fulfills requirement B,
- * omit change from AHS to AFS */
- best_avg_db = 0;
- for (i = 0; i < candidates; i++) {
- /* delete subscriber that just have handovered */
- if (clist[i].lchan == delete_lchan)
- clist[i].lchan = NULL;
- /* omit all subscribers that are handovered */
- if (!clist[i].lchan)
- continue;
-
- /* Do not resolve congestion towards remote BSS, which would
cause oscillation if the
- * remote BSS is also congested. */
- /* TODO: attempt inter-BSC HO if no local cells qualify, and
rely on the remote BSS to
- * deny receiving the handover if it also considers itself
congested. Maybe do that only
- * when the cell is absolutely full, i.e. not only
min-free-slots. (x) */
- if (!clist[i].bts)
- continue;
-
- if (!(clist[i].requirements & REQUIREMENT_B_MASK))
- continue;
- /* omit assignment from AHS to AFS */
- if (clist[i].lchan->ts->trx->bts == clist[i].bts
- && clist[i].lchan->type == GSM_LCHAN_TCH_H
- && (clist[i].requirements & REQUIREMENT_B_TCHF))
- continue;
- /* omit candidates that will not solve/reduce congestion */
- if (clist[i].lchan->type == GSM_LCHAN_TCH_F
- && tchf_congestion <= 0)
- continue;
- if (clist[i].lchan->type == GSM_LCHAN_TCH_H
- && tchh_congestion <= 0)
- continue;
-
- avg = clist[i].avg;
- /* improve AHS */
- if (clist[i].lchan->tch_mode == GSM48_CMODE_SPEECH_AMR
- && clist[i].lchan->type == GSM_LCHAN_TCH_H
- && (clist[i].requirements & REQUIREMENT_B_TCHF)) {
- avg += ho_get_hodec2_afs_bias_rxlev(clist[i].bts->ho);
- is_improved = 1;
- } else
- is_improved = 0;
- LOGPHOCAND(&clist[i], LOGL_DEBUG, "candidate %d: avg=%d
best_avg_db=%d\n",
- i, avg, best_avg_db);
- pick_better_lchan_to_move(true, &best_cand, &best_avg_db,
&clist[i], avg);
- }
-
- /* perform handover, if there is a candidate */
+ /* select best candidate that does not cause congestion in the target.
+ * Do not resolve congestion towards remote BSS, which would cause
oscillation if the remote BSS is also
+ * congested.
+ * Treating specially below: upgrading TCH/H to TCH/F within the same
cell, so omit here.
+ */
+ /* TODO: attempt inter-BSC HO if no local cells qualify, and rely on
the remote BSS to
+ * deny receiving the handover if it also considers itself congested.
Maybe do that only
+ * when the cell is absolutely full, i.e. not only min-free-slots. (x)
*/
+ best_cand = pick_best_candidate(&is_improved, clist, candidates,
+ /* want_highest_db */ true,
+ /* omit_intra_cell_upgrade_to_tchf */
true,
+ /* only_intra_cell_upgrade_to_tchf */
false,
+ REQUIREMENT_B_MASK);
if (best_cand) {
any_ho = 1;
LOGPHOCAND(best_cand, LOGL_DEBUG, "Best candidate: RX level
%d%s\n",
@@ -1650,59 +1689,29 @@
#if 0
next_b2:
#endif
- /* select worst candidate that fulfills requirement B,
- * select candidates that change from AHS to AFS only */
- if (tchh_congestion > 0) {
- /* since this will only check half rate channels, it will
- * only need to be checked, if tchh is congested */
- worst_avg_db = 999;
- for (i = 0; i < candidates; i++) {
- /* delete subscriber that just have handovered */
- if (clist[i].lchan == delete_lchan)
- clist[i].lchan = NULL;
- /* omit all subscribers that are handovered */
- if (!clist[i].lchan)
- continue;
-
- /* Do not resolve congestion towards remote BSS, which
would cause oscillation if
- * the remote BSS is also congested. */
- /* TODO: see (x) above */
- if (!clist[i].bts)
- continue;
-
- if (!(clist[i].requirements & REQUIREMENT_B_MASK))
- continue;
- /* omit all but assignment from AHS to AFS */
- if (clist[i].lchan->ts->trx->bts != clist[i].bts
- || clist[i].lchan->type != GSM_LCHAN_TCH_H
- || !(clist[i].requirements & REQUIREMENT_B_TCHF))
- continue;
-
- avg = clist[i].avg;
- /* improve AHS */
- if (clist[i].lchan->tch_mode == GSM48_CMODE_SPEECH_AMR
- && clist[i].lchan->type == GSM_LCHAN_TCH_H) {
- avg +=
ho_get_hodec2_afs_bias_rxlev(clist[i].bts->ho);
- is_improved = 1;
- } else
- is_improved = 0;
- pick_better_lchan_to_move(false, &worst_cand,
&worst_avg_db, &clist[i], avg);
- }
- }
-
- /* perform handover, if there is a candidate */
- if (worst_cand) {
+ /* For upgrading TCH/H to TCH/F within the same cell, we want to pick
the *lowest* average rxlev: for staying
+ * within the same cell, give the MS with the worst service more
bandwidth. When staying within the same cell,
+ * the target avg rxlev is identical to the source lchan rxlev, so it
is fine to use the same avg rxlev value,
+ * but simply pick the lowest one.
+ * Upgrading TCH/H channels obviously only applies when TCH/H is
actually congested. */
+ if (tchh_congestion > 0)
+ best_cand = pick_best_candidate(&is_improved, clist, candidates,
+ /* want_highest_db */ false,
+ /*
omit_intra_cell_upgrade_to_tchf */ false,
+ /*
only_intra_cell_upgrade_to_tchf */ true,
+ REQUIREMENT_B_MASK);
+ if (best_cand) {
any_ho = 1;
- LOGPHOCAND(worst_cand, LOGL_INFO, "Worst candidate: RX level %d
from TCH/H -> TCH/F%s\n",
- rxlev2dbm(worst_cand->avg),
+ LOGPHOCAND(best_cand, LOGL_INFO, "Worst candidate: RX level %d
from TCH/H -> TCH/F%s\n",
+ rxlev2dbm(best_cand->avg),
is_improved ? " (applied AHS -> AFS rxlev bias)" :
"");
- trigger_ho(worst_cand, worst_cand->requirements &
REQUIREMENT_B_MASK);
+ trigger_ho(best_cand, best_cand->requirements &
REQUIREMENT_B_MASK);
#if 0
/* if there is still congestion, mark lchan as deleted
* and redo this process */
tchh_congestion--;
if (tchh_congestion > 0) {
- delete_lchan = worst_cand->lchan;
+ delete_lchan = best_cand->lchan;
best_cand = NULL;
goto next_b2;
}
@@ -1718,51 +1727,14 @@
#if 0
next_c1:
#endif
- /* select best candidate that fulfills requirement C,
- * omit change from AHS to AFS */
- best_avg_db = 0;
- for (i = 0; i < candidates; i++) {
- /* delete subscriber that just have handovered */
- if (clist[i].lchan == delete_lchan)
- clist[i].lchan = NULL;
- /* omit all subscribers that are handovered */
- if (!clist[i].lchan)
- continue;
-
- /* Do not resolve congestion towards remote BSS, which would
cause oscillation if
- * the remote BSS is also congested. */
- /* TODO: see (x) above */
- if (!clist[i].bts)
- continue;
-
- if (!(clist[i].requirements & REQUIREMENT_C_MASK))
- continue;
- /* omit assignment from AHS to AFS */
- if (clist[i].lchan->ts->trx->bts == clist[i].bts
- && clist[i].lchan->type == GSM_LCHAN_TCH_H
- && (clist[i].requirements & REQUIREMENT_C_TCHF))
- continue;
- /* omit candidates that will not solve/reduce congestion */
- if (clist[i].lchan->type == GSM_LCHAN_TCH_F
- && tchf_congestion <= 0)
- continue;
- if (clist[i].lchan->type == GSM_LCHAN_TCH_H
- && tchh_congestion <= 0)
- continue;
-
- avg = clist[i].avg;
- /* improve AHS */
- if (clist[i].lchan->tch_mode == GSM48_CMODE_SPEECH_AMR
- && clist[i].lchan->type == GSM_LCHAN_TCH_H
- && (clist[i].requirements & REQUIREMENT_C_TCHF)) {
- avg += ho_get_hodec2_afs_bias_rxlev(clist[i].bts->ho);
- is_improved = 1;
- } else
- is_improved = 0;
- pick_better_lchan_to_move(true, &best_cand, &best_avg_db,
&clist[i], avg);
- }
-
- /* perform handover, if there is a candidate */
+ /* Select best candidate that balances congestion.
+ * Again no remote BSS.
+ * Again no TCH/H -> F upgrades within the same cell. */
+ best_cand = pick_best_candidate(&is_improved, clist, candidates,
+ /* want_highest_db */ true,
+ /* omit_intra_cell_upgrade_to_tchf */
true,
+ /* only_intra_cell_upgrade_to_tchf */
false,
+ REQUIREMENT_C_MASK);
if (best_cand) {
any_ho = 1;
LOGPHOCAND(best_cand, LOGL_INFO, "Best candidate: RX level
%d%s\n",
@@ -1796,62 +1768,29 @@
#if 0
next_c2:
#endif
- /* select worst candidate that fulfills requirement C,
- * select candidates that change from AHS to AFS only */
- if (tchh_congestion > 0) {
- /* since this will only check half rate channels, it will
- * only need to be checked, if tchh is congested */
- worst_avg_db = 999;
- for (i = 0; i < candidates; i++) {
- /* delete subscriber that just have handovered */
- if (clist[i].lchan == delete_lchan)
- clist[i].lchan = NULL;
- /* omit all subscribers that are handovered */
- if (!clist[i].lchan)
- continue;
-
- /* Do not resolve congestion towards remote BSS, which
would cause oscillation if
- * the remote BSS is also congested. */
- /* TODO: see (x) above */
- if (!clist[i].bts)
- continue;
-
- if (!(clist[i].requirements & REQUIREMENT_C_MASK))
- continue;
- /* omit all but assignment from AHS to AFS */
- if (clist[i].lchan->ts->trx->bts != clist[i].bts
- || clist[i].lchan->type != GSM_LCHAN_TCH_H
- || !(clist[i].requirements & REQUIREMENT_C_TCHF))
- continue;
-
- avg = clist[i].avg;
- /* improve AHS */
- if (clist[i].lchan->tch_mode == GSM48_CMODE_SPEECH_AMR
- && clist[i].lchan->type == GSM_LCHAN_TCH_H) {
- avg +=
ho_get_hodec2_afs_bias_rxlev(clist[i].bts->ho);
- is_improved = 1;
- } else
- is_improved = 0;
- LOGP(DHODEC, LOGL_DEBUG, "candidate %d: avg=%d
worst_avg_db=%d\n", i, avg,
- worst_avg_db);
- pick_better_lchan_to_move(false, &worst_cand,
&worst_avg_db, &clist[i], avg);
- }
- }
+ /* Look for upgrading TCH/H to TCH/F within the same cell, which
balances congestion, again upgrade the TCH/H
+ * lchan that has the worst reception: */
+ if (tchh_congestion > 0)
+ best_cand = pick_best_candidate(&is_improved, clist, candidates,
+ /* want_highest_db */ false,
+ /*
omit_intra_cell_upgrade_to_tchf */ false,
+ /*
only_intra_cell_upgrade_to_tchf */ true,
+ REQUIREMENT_C_MASK);
/* perform handover, if there is a candidate */
- if (worst_cand) {
+ if (best_cand) {
any_ho = 1;
- LOGPHOCAND(worst_cand, LOGL_INFO, "Worst candidate: RX level %d
from TCH/H -> TCH/F%s\n",
- rxlev2dbm(worst_cand->avg),
+ LOGPHOCAND(best_cand, LOGL_INFO, "Worst candidate: RX level %d
from TCH/H -> TCH/F%s\n",
+ rxlev2dbm(best_cand->avg),
is_improved ? " (applied AHS -> AFS rxlev bias)" :
"");
- trigger_ho(worst_cand, worst_cand->requirements &
REQUIREMENT_C_MASK);
+ trigger_ho(best_cand, best_cand->requirements &
REQUIREMENT_C_MASK);
#if 0
/* if there is still congestion, mark lchan as deleted
* and redo this process */
tchh_congestion--;
if (tchh_congestion > 0) {
- delete_lchan = worst_cand->lchan;
- worst_cand = NULL;
+ delete_lchan = best_cand->lchan;
+ best_cand = NULL;
goto next_c2;
}
#else
--
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Gerrit-Project: osmo-bsc
Gerrit-Branch: master
Gerrit-Change-Id: I7c32d08e490a88a7f044b0a71dc4b07d748dd572
Gerrit-Change-Number: 21971
Gerrit-PatchSet: 1
Gerrit-Owner: neels <[email protected]>
Gerrit-MessageType: newchange
