diff options
author | Neels Hofmeyr <nhofmeyr@sysmocom.de> | 2017-07-13 02:03:50 +0200 |
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committer | Neels Hofmeyr <neels@hofmeyr.de> | 2017-08-30 14:14:58 +0200 |
commit | ee6cfdc0d9710e3a69c8e1939eb21c8f2b759885 (patch) | |
tree | ed5aeb0979a1838778649078847a1ed6caa6b1a4 /src/libbsc/handover_decision.c | |
parent | 6c809185ee86d318d10205756bb6d91914d11fdf (diff) |
split off osmo-sgsn: remove files, apply build1.1.0
Change-Id: I5d27ff93e56cd13e0e70edd15e2080201e35e91f
Diffstat (limited to 'src/libbsc/handover_decision.c')
-rw-r--r-- | src/libbsc/handover_decision.c | 325 |
1 files changed, 0 insertions, 325 deletions
diff --git a/src/libbsc/handover_decision.c b/src/libbsc/handover_decision.c deleted file mode 100644 index 8d7e047b7..000000000 --- a/src/libbsc/handover_decision.c +++ /dev/null @@ -1,325 +0,0 @@ -/* Handover Decision making for Inter-BTS (Intra-BSC) Handover. This - * only implements the handover algorithm/decision, but not execution - * of it */ - -/* (C) 2009 by Harald Welte <laforge@gnumonks.org> - * - * All Rights Reserved - * - * This program is free software; you can redistribute it and/or modify - * it under the terms of the GNU Affero General Public License as published by - * the Free Software Foundation; either version 3 of the License, or - * (at your option) any later version. - * - * This program is distributed in the hope that it will be useful, - * but WITHOUT ANY WARRANTY; without even the implied warranty of - * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the - * GNU Affero General Public License for more details. - * - * You should have received a copy of the GNU Affero General Public License - * along with this program. If not, see <http://www.gnu.org/licenses/>. - * - */ - -#include <stdlib.h> -#include <errno.h> - -#include <osmocom/core/msgb.h> -#include <openbsc/debug.h> -#include <openbsc/gsm_data.h> -#include <openbsc/meas_rep.h> -#include <openbsc/signal.h> -#include <osmocom/core/talloc.h> -#include <openbsc/handover.h> -#include <osmocom/gsm/gsm_utils.h> - -/* Get reference to a neighbor cell on a given BCCH ARFCN */ -static struct gsm_bts *gsm_bts_neighbor(const struct gsm_bts *bts, - uint16_t arfcn, uint8_t bsic) -{ - struct gsm_bts *neigh; - /* FIXME: use some better heuristics here to determine which cell - * using this ARFCN really is closest to the target cell. For - * now we simply assume that each ARFCN will only be used by one - * cell */ - - llist_for_each_entry(neigh, &bts->network->bts_list, list) { - /* FIXME: this is probably returning the same bts again!? */ - if (neigh->c0->arfcn == arfcn && - neigh->bsic == bsic) - return neigh; - } - - return NULL; -} - - -/* issue handover to a cell identified by ARFCN and BSIC */ -static int handover_to_arfcn_bsic(struct gsm_lchan *lchan, - uint16_t arfcn, uint8_t bsic) -{ - struct gsm_bts *new_bts; - - /* resolve the gsm_bts structure for the best neighbor */ - new_bts = gsm_bts_neighbor(lchan->ts->trx->bts, arfcn, bsic); - if (!new_bts) { - LOGP(DHO, LOGL_NOTICE, "unable to determine neighbor BTS " - "for ARFCN %u BSIC %u ?!?\n", arfcn, bsic); - return -EINVAL; - } - - /* and actually try to handover to that cell */ - return bsc_handover_start(lchan, new_bts); -} - -/* did we get a RXLEV for a given cell in the given report? */ -static int rxlev_for_cell_in_rep(struct gsm_meas_rep *mr, - uint16_t arfcn, uint8_t bsic) -{ - int i; - - for (i = 0; i < mr->num_cell; i++) { - struct gsm_meas_rep_cell *mrc = &mr->cell[i]; - - /* search for matching report */ - if (!(mrc->arfcn == arfcn && mrc->bsic == bsic)) - continue; - - mrc->flags |= MRC_F_PROCESSED; - return mrc->rxlev; - } - return -ENODEV; -} - -/* obtain averaged rxlev for given neighbor */ -static int neigh_meas_avg(struct neigh_meas_proc *nmp, int window) -{ - unsigned int i, idx; - int avg = 0; - - idx = calc_initial_idx(ARRAY_SIZE(nmp->rxlev), - nmp->rxlev_cnt % ARRAY_SIZE(nmp->rxlev), - window); - - for (i = 0; i < window; i++) { - int j = (idx+i) % ARRAY_SIZE(nmp->rxlev); - - avg += nmp->rxlev[j]; - } - - return avg / window; -} - -/* find empty or evict bad neighbor */ -static struct neigh_meas_proc *find_evict_neigh(struct gsm_lchan *lchan) -{ - int j, worst = 999999; - struct neigh_meas_proc *nmp_worst = NULL; - - /* first try to find an empty/unused slot */ - for (j = 0; j < ARRAY_SIZE(lchan->neigh_meas); j++) { - struct neigh_meas_proc *nmp = &lchan->neigh_meas[j]; - if (!nmp->arfcn) - return nmp; - } - - /* no empty slot found. evict worst neighbor from list */ - for (j = 0; j < ARRAY_SIZE(lchan->neigh_meas); j++) { - struct neigh_meas_proc *nmp = &lchan->neigh_meas[j]; - int avg = neigh_meas_avg(nmp, MAX_WIN_NEIGH_AVG); - if (!nmp_worst || avg < worst) { - worst = avg; - nmp_worst = nmp; - } - } - - return nmp_worst; -} - -/* process neighbor cell measurement reports */ -static void process_meas_neigh(struct gsm_meas_rep *mr) -{ - int i, j, idx; - - /* for each reported cell, try to update global state */ - for (j = 0; j < ARRAY_SIZE(mr->lchan->neigh_meas); j++) { - struct neigh_meas_proc *nmp = &mr->lchan->neigh_meas[j]; - unsigned int idx; - int rxlev; - - /* skip unused entries */ - if (!nmp->arfcn) - continue; - - rxlev = rxlev_for_cell_in_rep(mr, nmp->arfcn, nmp->bsic); - idx = nmp->rxlev_cnt % ARRAY_SIZE(nmp->rxlev); - if (rxlev >= 0) { - nmp->rxlev[idx] = rxlev; - nmp->last_seen_nr = mr->nr; - } else - nmp->rxlev[idx] = 0; - nmp->rxlev_cnt++; - } - - /* iterate over list of reported cells, check if we did not - * process all of them */ - for (i = 0; i < mr->num_cell; i++) { - struct gsm_meas_rep_cell *mrc = &mr->cell[i]; - struct neigh_meas_proc *nmp; - - if (mrc->flags & MRC_F_PROCESSED) - continue; - - nmp = find_evict_neigh(mr->lchan); - - nmp->arfcn = mrc->arfcn; - nmp->bsic = mrc->bsic; - - idx = nmp->rxlev_cnt % ARRAY_SIZE(nmp->rxlev); - nmp->rxlev[idx] = mrc->rxlev; - nmp->rxlev_cnt++; - nmp->last_seen_nr = mr->nr; - - mrc->flags |= MRC_F_PROCESSED; - } -} - -/* attempt to do a handover */ -static int attempt_handover(struct gsm_meas_rep *mr) -{ - struct gsm_network *net = mr->lchan->ts->trx->bts->network; - struct neigh_meas_proc *best_cell = NULL; - unsigned int best_better_db = 0; - int i, rc; - - /* find the best cell in this report that is at least RXLEV_HYST - * better than the current serving cell */ - - for (i = 0; i < ARRAY_SIZE(mr->lchan->neigh_meas); i++) { - struct neigh_meas_proc *nmp = &mr->lchan->neigh_meas[i]; - int avg, better; - - /* skip empty slots */ - if (nmp->arfcn == 0) - continue; - - /* caculate average rxlev for this cell over the window */ - avg = neigh_meas_avg(nmp, net->handover.win_rxlev_avg_neigh); - - /* check if hysteresis is fulfilled */ - if (avg < mr->dl.full.rx_lev + net->handover.pwr_hysteresis) - continue; - - better = avg - mr->dl.full.rx_lev; - if (better > best_better_db) { - best_cell = nmp; - best_better_db = better; - } - } - - if (!best_cell) - return 0; - - LOGP(DHO, LOGL_INFO, "%s: Cell on ARFCN %u is better: ", - gsm_ts_name(mr->lchan->ts), best_cell->arfcn); - if (!net->handover.active) { - LOGPC(DHO, LOGL_INFO, "Skipping, Handover disabled\n"); - return 0; - } - - rc = handover_to_arfcn_bsic(mr->lchan, best_cell->arfcn, best_cell->bsic); - switch (rc) { - case 0: - LOGPC(DHO, LOGL_INFO, "Starting handover\n"); - break; - case -ENOSPC: - LOGPC(DHO, LOGL_INFO, "No channel available\n"); - break; - case -EBUSY: - LOGPC(DHO, LOGL_INFO, "Handover already active\n"); - break; - default: - LOGPC(DHO, LOGL_ERROR, "Unknown error\n"); - } - return rc; -} - -/* process an already parsed measurement report and decide if we want to - * attempt a handover */ -static int process_meas_rep(struct gsm_meas_rep *mr) -{ - struct gsm_network *net = mr->lchan->ts->trx->bts->network; - enum meas_rep_field dlev, dqual; - int av_rxlev; - - /* we currently only do handover for TCH channels */ - switch (mr->lchan->type) { - case GSM_LCHAN_TCH_F: - case GSM_LCHAN_TCH_H: - break; - default: - return 0; - } - - if (mr->flags & MEAS_REP_F_DL_DTX) { - dlev = MEAS_REP_DL_RXLEV_SUB; - dqual = MEAS_REP_DL_RXQUAL_SUB; - } else { - dlev = MEAS_REP_DL_RXLEV_FULL; - dqual = MEAS_REP_DL_RXQUAL_FULL; - } - - /* parse actual neighbor cell info */ - if (mr->num_cell > 0 && mr->num_cell < 7) - process_meas_neigh(mr); - - av_rxlev = get_meas_rep_avg(mr->lchan, dlev, - net->handover.win_rxlev_avg); - - /* Interference HO */ - if (rxlev2dbm(av_rxlev) > -85 && - meas_rep_n_out_of_m_be(mr->lchan, dqual, 3, 4, 5)) - return attempt_handover(mr); - - /* Bad Quality */ - if (meas_rep_n_out_of_m_be(mr->lchan, dqual, 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; - -} - -static int ho_dec_sig_cb(unsigned int subsys, unsigned int signal, - void *handler_data, void *signal_data) -{ - struct lchan_signal_data *lchan_data; - - if (subsys != SS_LCHAN) - return 0; - - lchan_data = signal_data; - switch (signal) { - case S_LCHAN_MEAS_REP: - process_meas_rep(lchan_data->mr); - break; - } - - return 0; -} - -void on_dso_load_ho_dec(void) -{ - osmo_signal_register_handler(SS_LCHAN, ho_dec_sig_cb, NULL); -} |