2009-12-16 23:31:10 +00:00
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/* Handover Decision making for Inter-BTS (Intra-BSC) Handover. This
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* only implements the handover algorithm/decision, but not execution
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* of it */
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/* (C) 2009 by Harald Welte <laforge@gnumonks.org>
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*
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* All Rights Reserved
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*
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* This program is free software; you can redistribute it and/or modify
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2011-01-01 14:25:50 +00:00
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* it under the terms of the GNU Affero General Public License as published by
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* the Free Software Foundation; either version 3 of the License, or
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2009-12-16 23:31:10 +00:00
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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2011-01-01 14:25:50 +00:00
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* GNU Affero General Public License for more details.
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2009-12-16 23:31:10 +00:00
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*
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2011-01-01 14:25:50 +00:00
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* You should have received a copy of the GNU Affero General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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2009-12-16 23:31:10 +00:00
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*
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*/
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#include <stdlib.h>
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#include <errno.h>
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|
split 'libosmocore' from openbsc codebase
This library is intended to collect all generic/common funcitionality
of all Osmocom.org projects, including OpenBSC but also OsmocomBB
The library currently includes the following modules:
bitvec, comp128, gsm_utils, msgb, select, signal, statistics, talloc, timer,
tlv_parse, linuxlist
msgb allocation error debugging had to be temporarily disabled as it depends on
'debug.c' functionality which at the moment remains in OpenBSC
2010-02-20 15:24:02 +00:00
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|
#include <osmocore/msgb.h>
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2009-12-16 23:31:10 +00:00
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#include <openbsc/debug.h>
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#include <openbsc/gsm_data.h>
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#include <openbsc/meas_rep.h>
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#include <openbsc/signal.h>
|
split 'libosmocore' from openbsc codebase
This library is intended to collect all generic/common funcitionality
of all Osmocom.org projects, including OpenBSC but also OsmocomBB
The library currently includes the following modules:
bitvec, comp128, gsm_utils, msgb, select, signal, statistics, talloc, timer,
tlv_parse, linuxlist
msgb allocation error debugging had to be temporarily disabled as it depends on
'debug.c' functionality which at the moment remains in OpenBSC
2010-02-20 15:24:02 +00:00
|
|
|
#include <osmocore/talloc.h>
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2009-12-16 23:31:10 +00:00
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#include <openbsc/handover.h>
|
split 'libosmocore' from openbsc codebase
This library is intended to collect all generic/common funcitionality
of all Osmocom.org projects, including OpenBSC but also OsmocomBB
The library currently includes the following modules:
bitvec, comp128, gsm_utils, msgb, select, signal, statistics, talloc, timer,
tlv_parse, linuxlist
msgb allocation error debugging had to be temporarily disabled as it depends on
'debug.c' functionality which at the moment remains in OpenBSC
2010-02-20 15:24:02 +00:00
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#include <osmocore/gsm_utils.h>
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2009-12-16 23:31:10 +00:00
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2009-12-21 12:30:17 +00:00
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/* issue handover to a cell identified by ARFCN and BSIC */
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2009-12-16 23:31:10 +00:00
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static int handover_to_arfcn_bsic(struct gsm_lchan *lchan,
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u_int16_t arfcn, u_int8_t bsic)
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{
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struct gsm_bts *new_bts;
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/* resolve the gsm_bts structure for the best neighbor */
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new_bts = gsm_bts_neighbor(lchan->ts->trx->bts, arfcn, bsic);
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if (!new_bts) {
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2009-12-17 22:10:46 +00:00
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LOGP(DHO, LOGL_NOTICE, "unable to determine neighbor BTS "
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"for ARFCN %u BSIC %u ?!?\n", arfcn, bsic);
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2009-12-16 23:31:10 +00:00
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return -EINVAL;
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}
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/* and actually try to handover to that cell */
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return bsc_handover_start(lchan, new_bts);
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}
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2009-12-21 12:30:17 +00:00
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/* did we get a RXLEV for a given cell in the given report? */
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static int rxlev_for_cell_in_rep(struct gsm_meas_rep *mr,
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u_int16_t arfcn, u_int8_t bsic)
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2009-12-16 23:31:10 +00:00
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{
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int i;
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2009-12-21 12:30:17 +00:00
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for (i = 0; i < mr->num_cell; i++) {
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struct gsm_meas_rep_cell *mrc = &mr->cell[i];
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/* search for matching report */
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if (!(mrc->arfcn == arfcn && mrc->bsic == bsic))
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continue;
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mrc->flags |= MRC_F_PROCESSED;
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return mrc->rxlev;
|
2009-12-18 10:49:20 +00:00
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}
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2009-12-21 12:30:17 +00:00
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return -ENODEV;
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}
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2009-12-18 10:49:20 +00:00
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2009-12-21 12:30:17 +00:00
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/* obtain averaged rxlev for given neighbor */
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static int neigh_meas_avg(struct neigh_meas_proc *nmp, int window)
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{
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unsigned int i, idx;
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int avg = 0;
|
2009-12-16 23:31:10 +00:00
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2009-12-21 12:30:17 +00:00
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idx = calc_initial_idx(ARRAY_SIZE(nmp->rxlev),
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nmp->rxlev_cnt % ARRAY_SIZE(nmp->rxlev),
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window);
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for (i = 0; i < window; i++) {
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int j = (idx+i) % ARRAY_SIZE(nmp->rxlev);
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avg += nmp->rxlev[j];
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}
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return avg / window;
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}
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/* find empty or evict bad neighbor */
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static struct neigh_meas_proc *find_evict_neigh(struct gsm_lchan *lchan)
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{
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int j, worst = 999999;
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struct neigh_meas_proc *nmp_worst;
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/* first try to find an empty/unused slot */
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for (j = 0; j < ARRAY_SIZE(lchan->neigh_meas); j++) {
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struct neigh_meas_proc *nmp = &lchan->neigh_meas[j];
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if (!nmp->arfcn)
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return nmp;
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}
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/* no empty slot found. evict worst neighbor from list */
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for (j = 0; j < ARRAY_SIZE(lchan->neigh_meas); j++) {
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struct neigh_meas_proc *nmp = &lchan->neigh_meas[j];
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int avg = neigh_meas_avg(nmp, MAX_WIN_NEIGH_AVG);
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if (avg < worst) {
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worst = avg;
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nmp_worst = nmp;
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}
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}
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return nmp_worst;
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}
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/* process neighbor cell measurement reports */
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static void process_meas_neigh(struct gsm_meas_rep *mr)
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{
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int i, j, idx;
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/* for each reported cell, try to update global state */
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for (j = 0; j < ARRAY_SIZE(mr->lchan->neigh_meas); j++) {
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struct neigh_meas_proc *nmp = &mr->lchan->neigh_meas[j];
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unsigned int idx;
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int rxlev;
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/* skip unused entries */
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if (!nmp->arfcn)
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continue;
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rxlev = rxlev_for_cell_in_rep(mr, nmp->arfcn, nmp->bsic);
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idx = nmp->rxlev_cnt % ARRAY_SIZE(nmp->rxlev);
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if (rxlev >= 0) {
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nmp->rxlev[idx] = rxlev;
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nmp->last_seen_nr = mr->nr;
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} else
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nmp->rxlev[idx] = 0;
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nmp->rxlev_cnt++;
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}
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/* iterate over list of reported cells, check if we did not
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* process all of them */
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for (i = 0; i < mr->num_cell; i++) {
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struct gsm_meas_rep_cell *mrc = &mr->cell[i];
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struct neigh_meas_proc *nmp;
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if (mrc->flags & MRC_F_PROCESSED)
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continue;
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nmp = find_evict_neigh(mr->lchan);
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nmp->arfcn = mrc->arfcn;
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nmp->bsic = mrc->bsic;
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idx = nmp->rxlev_cnt % ARRAY_SIZE(nmp->rxlev);
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nmp->rxlev[idx] = mrc->rxlev;
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nmp->rxlev_cnt++;
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nmp->last_seen_nr = mr->nr;
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mrc->flags |= MRC_F_PROCESSED;
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}
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}
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/* attempt to do a handover */
|
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static int attempt_handover(struct gsm_meas_rep *mr)
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|
{
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struct gsm_network *net = mr->lchan->ts->trx->bts->network;
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struct neigh_meas_proc *best_cell = NULL;
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unsigned int best_better_db = 0;
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int i, rc;
|
2009-12-19 20:29:19 +00:00
|
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|
2009-12-16 23:31:10 +00:00
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|
/* find the best cell in this report that is at least RXLEV_HYST
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|
|
* better than the current serving cell */
|
2009-12-21 12:30:17 +00:00
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for (i = 0; i < ARRAY_SIZE(mr->lchan->neigh_meas); i++) {
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struct neigh_meas_proc *nmp = &mr->lchan->neigh_meas[i];
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|
int avg, better;
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|
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|
/* skip empty slots */
|
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|
|
if (nmp->arfcn == 0)
|
2009-12-16 23:31:10 +00:00
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|
continue;
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|
2009-12-21 12:30:17 +00:00
|
|
|
/* caculate average rxlev for this cell over the window */
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|
avg = neigh_meas_avg(nmp, net->handover.win_rxlev_avg_neigh);
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|
|
/* check if hysteresis is fulfilled */
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|
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if (avg < mr->dl.full.rx_lev + net->handover.pwr_hysteresis)
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|
continue;
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better = avg - mr->dl.full.rx_lev;
|
2009-12-16 23:31:10 +00:00
|
|
|
if (better > best_better_db) {
|
2009-12-21 12:30:17 +00:00
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best_cell = nmp;
|
2009-12-16 23:31:10 +00:00
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best_better_db = better;
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|
}
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}
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|
2009-12-21 12:30:17 +00:00
|
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if (!best_cell)
|
2009-12-19 20:41:52 +00:00
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return 0;
|
2009-12-16 23:31:10 +00:00
|
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|
2009-12-21 12:30:17 +00:00
|
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|
LOGP(DHO, LOGL_INFO, "%s: Cell on ARFCN %u is better: ",
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gsm_ts_name(mr->lchan->ts), best_cell->arfcn);
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|
|
if (!net->handover.active) {
|
2009-12-19 20:41:52 +00:00
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|
LOGPC(DHO, LOGL_INFO, "Skipping, Handover disabled\n");
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|
return 0;
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|
|
}
|
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|
2009-12-21 12:30:17 +00:00
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|
rc = handover_to_arfcn_bsic(mr->lchan, best_cell->arfcn, best_cell->bsic);
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|
switch (rc) {
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case 0:
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|
LOGPC(DHO, LOGL_INFO, "Starting handover\n");
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|
|
break;
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|
|
case -ENOSPC:
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|
|
LOGPC(DHO, LOGL_INFO, "No channel available\n");
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|
|
break;
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|
|
case -EBUSY:
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|
|
LOGPC(DHO, LOGL_INFO, "Handover already active\n");
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|
|
break;
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|
|
default:
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|
|
LOGPC(DHO, LOGL_ERROR, "Unknown error\n");
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|
|
}
|
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|
return rc;
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|
|
}
|
|
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|
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|
|
|
/* process an already parsed measurement report and decide if we want to
|
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|
|
* attempt a handover */
|
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|
|
static int process_meas_rep(struct gsm_meas_rep *mr)
|
|
|
|
{
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|
|
struct gsm_network *net = mr->lchan->ts->trx->bts->network;
|
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|
|
int av_rxlev;
|
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|
|
|
|
|
|
/* we currently only do handover for TCH channels */
|
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|
|
switch (mr->lchan->type) {
|
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|
|
case GSM_LCHAN_TCH_F:
|
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|
|
case GSM_LCHAN_TCH_H:
|
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|
|
break;
|
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|
|
default:
|
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|
|
return 0;
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|
|
}
|
|
|
|
|
|
|
|
/* parse actual neighbor cell info */
|
|
|
|
if (mr->num_cell > 0 && mr->num_cell < 7)
|
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|
|
process_meas_neigh(mr);
|
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|
|
|
|
|
|
av_rxlev = get_meas_rep_avg(mr->lchan, MEAS_REP_DL_RXLEV_FULL,
|
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|
|
net->handover.win_rxlev_avg);
|
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|
|
|
|
|
|
/* Interference HO */
|
|
|
|
if (rxlev2dbm(av_rxlev) > -85 &&
|
|
|
|
meas_rep_n_out_of_m_be(mr->lchan, MEAS_REP_DL_RXQUAL_FULL,
|
|
|
|
3, 4, 5))
|
|
|
|
return attempt_handover(mr);
|
|
|
|
|
|
|
|
/* Bad Quality */
|
|
|
|
if (meas_rep_n_out_of_m_be(mr->lchan, MEAS_REP_DL_RXQUAL_FULL,
|
|
|
|
3, 4, 5))
|
|
|
|
return attempt_handover(mr);
|
|
|
|
|
|
|
|
/* Low Level */
|
|
|
|
if (rxlev2dbm(av_rxlev) <= -110)
|
|
|
|
return attempt_handover(mr);
|
|
|
|
|
|
|
|
/* Distance */
|
|
|
|
if (mr->ms_l1.ta > net->handover.max_distance)
|
|
|
|
return attempt_handover(mr);
|
|
|
|
|
|
|
|
/* Power Budget AKA Better Cell */
|
|
|
|
if ((mr->nr % net->handover.pwr_interval) == 0)
|
|
|
|
return attempt_handover(mr);
|
|
|
|
|
|
|
|
return 0;
|
|
|
|
|
2009-12-16 23:31:10 +00:00
|
|
|
}
|
|
|
|
|
|
|
|
static int ho_dec_sig_cb(unsigned int subsys, unsigned int signal,
|
|
|
|
void *handler_data, void *signal_data)
|
|
|
|
{
|
2010-12-27 12:28:20 +00:00
|
|
|
struct lchan_signal_data *lchan_data;
|
2009-12-16 23:31:10 +00:00
|
|
|
|
|
|
|
if (subsys != SS_LCHAN)
|
|
|
|
return 0;
|
|
|
|
|
2010-12-27 12:28:20 +00:00
|
|
|
lchan_data = signal_data;
|
2009-12-16 23:31:10 +00:00
|
|
|
switch (signal) {
|
|
|
|
case S_LCHAN_MEAS_REP:
|
2010-12-27 12:28:20 +00:00
|
|
|
process_meas_rep(lchan_data->mr);
|
2009-12-16 23:31:10 +00:00
|
|
|
break;
|
|
|
|
}
|
|
|
|
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
|
|
|
|
void on_dso_load_ho_dec(void)
|
|
|
|
{
|
|
|
|
register_signal_handler(SS_LCHAN, ho_dec_sig_cb, NULL);
|
|
|
|
}
|