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neels gerrit-no-reply at lists.osmocom.orgneels has uploaded this change for review. ( https://gerrit.osmocom.org/c/osmo-bsc/+/22265 ) Change subject: hodec2: fix congestion resolution on dyn TS ...................................................................... hodec2: fix congestion resolution on dyn TS For handover algorithm 2, properly figure out what effects the target cell will see for the *other* TCH kind when a handover would occupy a dynamic timeslot. Before this, only TCH/F or TCH/H would be regarded at a time. This introduces detection of whether a dynamic timeslot would be occupied by a handover, and how losing one unused dynamic timeslot affects the congestion situation for the TCH kind that is not targeted by the handover. In other words, if a handover to TCH/F causes congestion in TCH/H because of a dynamic timeslot becoming occupied, the handover will not be performed. Before this, oscillation situations could occur. A subsequent patch will do the same for congestion balancing. Related: SYS#5297 Change-Id: I1536b60f03cb0aeb6ba14a72b518aec82fa572fe --- M src/osmo-bsc/handover_decision_2.c M tests/handover/test_dyn_ts_congestion_tch_f_vs_tch_h.ho_vty 2 files changed, 37 insertions(+), 20 deletions(-) git pull ssh://gerrit.osmocom.org:29418/osmo-bsc refs/changes/65/22265/1 diff --git a/src/osmo-bsc/handover_decision_2.c b/src/osmo-bsc/handover_decision_2.c index 0362c9b..131a309 100644 --- a/src/osmo-bsc/handover_decision_2.c +++ b/src/osmo-bsc/handover_decision_2.c @@ -40,6 +40,7 @@ #include <osmocom/bsc/neighbor_ident.h> #include <osmocom/bsc/timeslot_fsm.h> #include <osmocom/bsc/bts.h> +#include <osmocom/bsc/lchan_select.h> #define LOGPHOBTS(bts, level, fmt, args...) \ LOGP(DHODEC, level, "(BTS %u) " fmt, bts->nr, ## args) @@ -118,6 +119,9 @@ int min_free_tchf; int free_tchh; int min_free_tchh; + /* Effects of occupying a dynamic timeslot: */ + int next_tchf_reduces_tchh; + int next_tchh_reduces_tchf; } target; }; @@ -637,11 +641,15 @@ /* the minimum free timeslots that are defined for this cell must * be maintained _after_ handover/assignment */ if (requirement & REQUIREMENT_A_TCHF) { - if (c->target.free_tchf - 1 >= c->target.min_free_tchf) + if (c->target.free_tchf - 1 >= c->target.min_free_tchf + && (!c->target.next_tchf_reduces_tchh + || c->target.free_tchh - c->target.next_tchf_reduces_tchh >= c->target.min_free_tchh)) requirement |= REQUIREMENT_B_TCHF; } if (requirement & REQUIREMENT_A_TCHH) { - if (c->target.free_tchh - 1 >= c->target.min_free_tchh) + if (c->target.free_tchh - 1 >= c->target.min_free_tchh + && (!c->target.next_tchh_reduces_tchf + || c->target.free_tchf - c->target.next_tchh_reduces_tchf >= c->target.min_free_tchf)) requirement |= REQUIREMENT_B_TCHH; } @@ -894,6 +902,8 @@ static void candidate_set_free_tch(struct ho_candidate *c) { + struct gsm_lchan *next_lchan; + c->current.free_tch = bts_count_free_ts(c->current.bts, c->current.lchan->ts->pchan_is); switch (c->current.lchan->ts->pchan_is) { case GSM_PCHAN_TCH_F: @@ -909,6 +919,21 @@ c->target.min_free_tchf = ho_get_hodec2_tchf_min_slots(c->target.bts->ho); c->target.free_tchh = bts_count_free_ts(c->target.bts, GSM_PCHAN_TCH_H); c->target.min_free_tchh = ho_get_hodec2_tchh_min_slots(c->target.bts->ho); + + /* Would the next TCH/F lchan convert a dynamic timeslot that currently counts for free TCH/H timeslots? */ + next_lchan = lchan_avail_by_type(c->target.bts, GSM_LCHAN_TCH_F); + if (next_lchan && next_lchan->ts->pchan_on_init == GSM_PCHAN_TCH_F_TCH_H_PDCH) + c->target.next_tchf_reduces_tchh = 2; + else + c->target.next_tchf_reduces_tchh = 0; + + /* Would the next TCH/H lchan convert a dynamic timeslot that currently counts for free TCH/F timeslots? */ + next_lchan = lchan_avail_by_type(c->target.bts, GSM_LCHAN_TCH_H); + if (next_lchan && next_lchan->ts->pchan_on_init == GSM_PCHAN_TCH_F_TCH_H_PDCH + && next_lchan->ts->pchan_is != GSM_PCHAN_TCH_H) + c->target.next_tchh_reduces_tchf = 1; + else + c->target.next_tchh_reduces_tchf = 0; } /* add candidate for re-assignment within the current cell */ diff --git a/tests/handover/test_dyn_ts_congestion_tch_f_vs_tch_h.ho_vty b/tests/handover/test_dyn_ts_congestion_tch_f_vs_tch_h.ho_vty index bc2c884..c5890a5 100644 --- a/tests/handover/test_dyn_ts_congestion_tch_f_vs_tch_h.ho_vty +++ b/tests/handover/test_dyn_ts_congestion_tch_f_vs_tch_h.ho_vty @@ -20,12 +20,8 @@ expect-no-chan meas-rep lchan 0 0 1 0 rxlev 20 rxqual 0 ta 0 neighbors 40 -# FAIL: should not handover because that results in congestion on TCH/H in bts 1 -expect-ho from lchan 0 0 1 0 to lchan 1 0 5 0 - -expect-ts-use trx 0 0 states * - - - pdch pdch pdch * -expect-ts-use trx 1 0 states * TCH/F TCH/F TCH/F TCH/HH TCH/F pdch * - +# no handover because that results in congestion on TCH/H in bts 1 +expect-no-chan ### @@ -34,11 +30,9 @@ meas-rep lchan * * * * rxlev 40 rxqual 0 ta 0 neighbors 30 congestion-check -# FAIL: really weird: handover one TCH/H to the same cell to TCH/F, taking up another dyn TS. -# TCH/H congestion hence actually gets worse. -expect-ho from lchan 1 0 4 1 to lchan 1 0 6 0 -expect-ts-use trx 0 0 states * - - - pdch pdch pdch * -expect-ts-use trx 1 0 states * TCH/F TCH/F TCH/F TCH/H- TCH/F TCH/F * +expect-ho from lchan 1 0 4 1 to lchan 0 0 4 0 +expect-ts-use trx 0 0 states * - - - TCH/H- pdch pdch * +expect-ts-use trx 1 0 states * TCH/F TCH/F TCH/F TCH/H- TCH/F pdch * ### @@ -65,12 +59,9 @@ expect-no-chan meas-rep lchan 0 * * * rxlev 30 rxqual 0 ta 0 neighbors 40 -# FAIL: back to bts 1 because of rxlev, plus moving TCH/H to TCH/F!? -expect-ho from lchan 0 0 4 0 to lchan 1 0 4 0 - -expect-ts-use trx 0 0 states * - - - pdch pdch pdch * -expect-ts-use trx 1 0 states * TCH/F TCH/F TCH/F TCH/F TCH/F TCH/F * - +# no HO because the target is congested on TCH/H. Moving to TCH/F would also +# reduce TCH/H lchans because it would convert another dyn TS. +expect-no-chan ### @@ -78,5 +69,6 @@ set-ts-use trx 1 0 states * TCH/F TCH/F TCH/F TCH/F TCH/F TCH/F * congestion-check +# FAIL: TCH/F occupy dynamic timeslots -- should hand over to bts 0 to free a +# dyn TS and reduce TCH/H congestion. expect-no-chan -# Stable situation now only because TCH/F has min-free-slots set to 0 -- To view, visit https://gerrit.osmocom.org/c/osmo-bsc/+/22265 To unsubscribe, or for help writing mail filters, visit https://gerrit.osmocom.org/settings Gerrit-Project: osmo-bsc Gerrit-Branch: master Gerrit-Change-Id: I1536b60f03cb0aeb6ba14a72b518aec82fa572fe Gerrit-Change-Number: 22265 Gerrit-PatchSet: 1 Gerrit-Owner: neels <nhofmeyr at sysmocom.de> Gerrit-MessageType: newchange -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.osmocom.org/pipermail/gerrit-log/attachments/20210117/2cbf0fa9/attachment.htm>