diff options
Diffstat (limited to 'src/host/trxcon/sched_lchan_rach.c')
| -rw-r--r-- | src/host/trxcon/sched_lchan_rach.c | 108 |
1 files changed, 108 insertions, 0 deletions
diff --git a/src/host/trxcon/sched_lchan_rach.c b/src/host/trxcon/sched_lchan_rach.c new file mode 100644 index 00000000..0e8d2e80 --- /dev/null +++ b/src/host/trxcon/sched_lchan_rach.c @@ -0,0 +1,108 @@ +/* + * OsmocomBB <-> SDR connection bridge + * TDMA scheduler: handlers for DL / UL bursts on logical channels + * + * (C) 2017 by Vadim Yanitskiy <axilirator@gmail.com> + * + * All Rights Reserved + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 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 General Public License along + * with this program; if not, write to the Free Software Foundation, Inc., + * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. + * + */ + +#include <errno.h> +#include <string.h> +#include <talloc.h> +#include <stdint.h> + +#include <arpa/inet.h> + +#include <osmocom/core/linuxlist.h> +#include <osmocom/core/logging.h> +#include <osmocom/core/bits.h> +#include <osmocom/core/msgb.h> +#include <osmocom/core/fsm.h> + +#include <osmocom/gsm/gsm_utils.h> +#include <osmocom/coding/gsm0503_coding.h> + +#include "l1ctl_proto.h" +#include "scheduler.h" +#include "sched_trx.h" +#include "logging.h" +#include "trx_if.h" +#include "trxcon.h" +#include "l1ctl.h" + +/** + * 41-bit RACH synchronization sequence + * GSM 05.02 Chapter 5.2.7 Access burst (AB) + */ +static ubit_t rach_synch_seq[] = { + 0, 1, 0, 0, 1, 0, 1, 1, 0, 1, 1, 1, 1, 1, + 1, 1, 1, 0, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, + 1, 0, 1, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, +}; + +/* Obtain a to-be-transmitted RACH burst */ +int tx_rach_fn(struct trx_instance *trx, struct trx_ts *ts, + uint32_t fn, enum trx_lchan_type chan, + uint8_t bid, uint16_t *nbits) +{ + struct trx_ts_prim *prim; + struct l1ctl_rach_req *req; + uint8_t burst[GSM_BURST_LEN]; + uint8_t payload[36]; + int rc; + + /* Get a message from TX queue */ + prim = llist_entry(ts->tx_prims.next, struct trx_ts_prim, list); + req = (struct l1ctl_rach_req *) prim->payload; + + /* Delay RACH sending according to offset value */ + if (req->offset-- > 0) + return 0; + + /* Encode payload */ + rc = gsm0503_rach_encode(payload, &req->ra, trx->bsic); + if (rc) { + LOGP(DSCH, LOGL_ERROR, "Could not encode RACH burst\n"); + return rc; + } + + /* Compose RACH burst */ + memset(burst, 0, 8); /* TB */ + memcpy(burst + 8, rach_synch_seq, 41); /* sync seq */ + memcpy(burst + 49, payload, 36); /* payload */ + memset(burst + 85, 0, 63); /* TB + GP */ + + LOGP(DSCH, LOGL_DEBUG, "Transmitting RACH fn=%u\n", fn); + + /* Send burst to transceiver */ + rc = trx_if_tx_burst(trx, ts->index, fn, 10, burst); + if (rc) { + LOGP(DSCH, LOGL_ERROR, "Could not send burst to transceiver\n"); + return rc; + } + + /* Confirm RACH request */ + l1ctl_tx_rach_conf(trx->l1l, fn); + + /* Remove primitive from queue and free memory */ + llist_del(&prim->list); + talloc_free(prim); + + return 0; +} |