diff options
Diffstat (limited to 'src/common/handover.c')
| -rw-r--r-- | src/common/handover.c | 164 |
1 files changed, 164 insertions, 0 deletions
diff --git a/src/common/handover.c b/src/common/handover.c new file mode 100644 index 00000000..54b131ff --- /dev/null +++ b/src/common/handover.c @@ -0,0 +1,164 @@ +/* Paging message encoding + queue management */ + +/* (C) 2012-2013 by Harald Welte <laforge@gnumonks.org> + * Andreas Eversberg <jolly@eversberg.eu> + * (C) 2014 by Holger Hans Peter Freyther + * + * 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 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 <stdint.h> +#include <errno.h> + +#include <osmocom/gsm/protocol/gsm_04_08.h> +#include <osmocom/gsm/rsl.h> + +#include <osmo-bts/bts.h> +#include <osmo-bts/bts_model.h> +#include <osmo-bts/rsl.h> +#include <osmo-bts/logging.h> +#include <osmo-bts/handover.h> +#include <osmo-bts/l1sap.h> + +/* Transmit a handover related PHYS INFO on given lchan */ +static int ho_tx_phys_info(struct gsm_lchan *lchan) +{ + struct msgb *msg = msgb_alloc_headroom(1024, 128, "PHYS INFO"); + struct gsm48_hdr *gh; + + if (!msg) + return -ENOMEM; + + LOGP(DHO, LOGL_INFO, + "%s Sending PHYSICAL INFORMATION to MS.\n", + gsm_lchan_name(lchan)); + + /* Build RSL UNITDATA REQUEST message with 04.08 PHYS INFO */ + msg->l3h = msg->data; + gh = (struct gsm48_hdr *) msgb_put(msg, sizeof(*gh)); + gh->proto_discr = GSM48_PDISC_RR; + gh->msg_type = GSM48_MT_RR_HANDO_INFO; + msgb_put_u8(msg, lchan->rqd_ta); + + rsl_rll_push_l3(msg, RSL_MT_UNIT_DATA_REQ, gsm_lchan2chan_nr(lchan), + 0x00, 0); + + lapdm_rslms_recvmsg(msg, &lchan->lapdm_ch); + return 0; +} + +/* timer call-back for T3105 (handover PHYS INFO re-transmit) */ +static void ho_t3105_cb(void *data) +{ + struct gsm_lchan *lchan = data; + struct gsm_bts *bts = lchan->ts->trx->bts; + + LOGP(DHO, LOGL_INFO, "%s T3105 timeout (%d resends left)\n", + gsm_lchan_name(lchan), bts->ny1 - lchan->ho.phys_info_count); + + if (lchan->state != LCHAN_S_ACTIVE) { + LOGP(DHO, LOGL_NOTICE, + "%s is in not active. It is in state %s. Ignoring\n", + gsm_lchan_name(lchan), gsm_lchans_name(lchan->state)); + return; + } + + if (lchan->ho.phys_info_count >= bts->ny1) { + /* HO Abort */ + LOGP(DHO, LOGL_NOTICE, "%s NY1 reached, sending CONNection " + "FAILure to BSC.\n", gsm_lchan_name(lchan)); + rsl_tx_conn_fail(lchan, RSL_ERR_HANDOVER_ACC_FAIL); + return; + } + + ho_tx_phys_info(lchan); + lchan->ho.phys_info_count++; + osmo_timer_schedule(&lchan->ho.t3105, 0, bts->t3105_ms * 1000); +} + +/* received random access on dedicated channel */ +void handover_rach(struct gsm_lchan *lchan, uint8_t ra, uint8_t acc_delay) +{ + struct gsm_bts *bts = lchan->ts->trx->bts; + + /* Ignore invalid handover ref */ + if (lchan->ho.ref != ra) { + LOGP(DHO, LOGL_INFO, "%s RACH on dedicated channel received, but " + "ra=0x%02x != expected ref=0x%02x. (This is no bug)\n", + gsm_lchan_name(lchan), ra, lchan->ho.ref); + return; + } + + /* Ignore handover on channels other than DCCH and SACCH */ + if (lchan->type != GSM_LCHAN_SDCCH && lchan->type != GSM_LCHAN_TCH_H && + lchan->type != GSM_LCHAN_TCH_F) { + LOGP(DHO, LOGL_ERROR, "%s handover RACH received on %s?!\n", + gsm_lchan_name(lchan), gsm_lchant_name(lchan->type)); + return; + } + + LOGP(DHO, LOGL_NOTICE, + "%s RACH on dedicated channel type %s received with TA=%u, ref=%u\n", + gsm_lchan_name(lchan), gsm_lchant_name(lchan->type), acc_delay, ra); + + /* Set timing advance */ + lchan->rqd_ta = acc_delay; + + /* Stop handover detection, wait for valid frame */ + lchan->ho.active = HANDOVER_WAIT_FRAME; + if (l1sap_chan_modify(lchan->ts->trx, gsm_lchan2chan_nr(lchan)) != 0) { + LOGP(DHO, LOGL_ERROR, + "%s failed to modify channel after handover\n", + gsm_lchan_name(lchan)); + rsl_tx_conn_fail(lchan, RSL_ERR_HANDOVER_ACC_FAIL); + return; + } + + /* Send HANDover DETect to BSC */ + rsl_tx_hando_det(lchan, &lchan->rqd_ta); + + /* Send PHYS INFO */ + lchan->ho.phys_info_count = 1; + ho_tx_phys_info(lchan); + + /* Start T3105 */ + LOGP(DHO, LOGL_DEBUG, + "%s Starting T3105 with %u ms\n", + gsm_lchan_name(lchan), bts->t3105_ms); + lchan->ho.t3105.cb = ho_t3105_cb; + lchan->ho.t3105.data = lchan; + osmo_timer_schedule(&lchan->ho.t3105, 0, bts->t3105_ms * 1000); +} + +/* received frist valid data frame on dedicated channel */ +void handover_frame(struct gsm_lchan *lchan) +{ + LOGP(DHO, LOGL_INFO, + "%s First valid frame detected\n", gsm_lchan_name(lchan)); + handover_reset(lchan); +} + +/* release handover state */ +void handover_reset(struct gsm_lchan *lchan) +{ + /* Stop T3105 */ + osmo_timer_del(&lchan->ho.t3105); + + /* Handover process is done */ + lchan->ho.active = HANDOVER_NONE; +} |