diff options
| -rw-r--r-- | src/common/l1sap.c | 72 |
1 files changed, 56 insertions, 16 deletions
diff --git a/src/common/l1sap.c b/src/common/l1sap.c index 968237f3..0ce1e4a0 100644 --- a/src/common/l1sap.c +++ b/src/common/l1sap.c @@ -352,18 +352,67 @@ static int to_gsmtap(struct gsm_bts_trx *trx, struct osmo_phsap_prim *l1sap) return 0; } +/* Calculate the number of RACH slots that expire in a certain GSM frame + * See also 3GPP TS 05.02 Clause 7 Table 5 of 9 */ +static unsigned int calc_exprd_rach_frames(struct gsm_bts *bts, uint32_t fn) +{ + int rach_frames_expired = 0; + uint8_t ccch_conf; + struct gsm48_system_information_type_3 *si3; + unsigned int blockno; + + si3 = GSM_BTS_SI(bts, SYSINFO_TYPE_3); + ccch_conf = si3->control_channel_desc.ccch_conf; + + if (ccch_conf == RSL_BCCH_CCCH_CONF_1_C) { + /* It is possible to combine a CCCH with an SDCCH4, in this + * case the CCCH will have to share the available frames with + * the other channel, this results in a limited number of + * available rach slots */ + blockno = fn % 51; + if (blockno == 4 || blockno == 5 + || (blockno >= 15 && blockno <= 36) || blockno == 45 + || blockno == 46) + rach_frames_expired = 1; + } else { + /* It is possible to have multiple CCCH channels on + * different physical channels (large cells), this + * also multiplies the available/expired RACH channels. + * See also TS 04.08, Chapter 10.5.2.11, table 10.29 */ + if (ccch_conf == RSL_BCCH_CCCH_CONF_2_NC) + rach_frames_expired = 2; + if (ccch_conf == RSL_BCCH_CCCH_CONF_3_NC) + rach_frames_expired = 3; + if (ccch_conf == RSL_BCCH_CCCH_CONF_4_NC) + rach_frames_expired = 4; + else + rach_frames_expired = 1; + } + + /* Each Frame has room for 4 RACH slots, since RACH + * slots are short enough to fit into a single radio + * burst, so we need to multiply the final result by 4 */ + return rach_frames_expired * 4; +} + /* time information received from bts model */ static int l1sap_info_time_ind(struct gsm_bts *bts, - struct osmo_phsap_prim *l1sap, - struct info_time_ind_param *info_time_ind) + struct osmo_phsap_prim *l1sap, + struct info_time_ind_param *info_time_ind) { struct gsm_bts_trx *trx; struct gsm_bts_role_bts *btsb = bts->role; - - int frames_expired = info_time_ind->fn - btsb->gsm_time.fn; + int frames_expired; DEBUGP(DL1P, "MPH_INFO time ind %u\n", info_time_ind->fn); + /* Calculate and check frame difference */ + frames_expired = info_time_ind->fn - btsb->gsm_time.fn; + if (frames_expired > 1) { + LOGP(DL1P, LOGL_ERROR, + "Invalid condition detected: Frame difference is > 1!\n"); + } + /* Update our data structures with the current GSM time */ gsm_fn2gsmtime(&btsb->gsm_time, info_time_ind->fn); @@ -373,24 +422,15 @@ static int l1sap_info_time_ind(struct gsm_bts *bts, /* check if the measurement period of some lchan has ended * and pre-compute the respective measurement */ llist_for_each_entry(trx, &bts->trx_list, list) - trx_meas_check_compute(trx, info_time_ind->fn - 1); + trx_meas_check_compute(trx, info_time_ind->fn - 1); /* increment number of RACH slots that have passed by since the * last time indication */ - if (trx == bts->c0) { - unsigned int num_rach_per_frame; - /* 27 / 51 taken from TS 05.01 Figure 3 */ - if (bts->c0->ts[0].pchan == GSM_PCHAN_CCCH_SDCCH4) - num_rach_per_frame = 27; - else - num_rach_per_frame = 51; - - btsb->load.rach.total += frames_expired * num_rach_per_frame; - } + btsb->load.rach.total += + calc_exprd_rach_frames(bts, info_time_ind->fn) * frames_expired; return 0; } - /* measurement information received from bts model */ static int l1sap_info_meas_ind(struct gsm_bts_trx *trx, struct osmo_phsap_prim *l1sap, |