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pcu_l1_if.cpp: handle TLLI based IMMEDIATE ASSIGNMENT confirmation 

The IMMEDIATE ASSIGNMENT for downlink TBFs must be confirmed by the
receiving end (BSC/BTS) in order to set the timers in the PCU correctly.

When the PCU is used in a BSC co-located scheme (Ericsson RBS). The TLLI
is used as an identifier to confirm a specific IMMEDIATE ASSIGNMENT.

Change-Id: Icf7ca34500984239ee877ee71fd9c126b5eb3480
Related: OS#5198
This commit is contained in:
Philipp Maier 2023-02-01 16:10:52 +01:00
parent d8cea3c618
commit 7c3fd98c90
3 changed files with 61 additions and 11 deletions
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44
src/bts.cpp
View File

@ -668,13 +668,10 @@ int bts_tfi_find_free(const struct gprs_rlcmac_bts *bts, enum gprs_rlcmac_tbf_di
return best_first_tfi;
}
int bts_rcv_imm_ass_cnf(struct gprs_rlcmac_bts *bts, const uint8_t *data, uint32_t fn)
static int tlli_from_imm_ass(uint32_t *tlli, const uint8_t *data, uint32_t fn)
{
struct gprs_rlcmac_dl_tbf *dl_tbf;
const struct gsm48_imm_ass *imm_ass = (struct gsm48_imm_ass *)data;
uint8_t plen;
uint32_t tlli;
GprsMs *ms;
/* Move to IA Rest Octets: TS 44.018 9.1.18 "The L2 pseudo length of
* this message is the sum of lengths of all information elements
@ -692,12 +689,41 @@ int bts_rcv_imm_ass_cnf(struct gprs_rlcmac_bts *bts, const uint8_t *data, uint32
}
/* get TLLI from downlink assignment */
tlli = (uint32_t)((*data++) & 0xf) << 28;
tlli |= (*data++) << 20;
tlli |= (*data++) << 12;
tlli |= (*data++) << 4;
tlli |= (*data++) >> 4;
*tlli = (uint32_t)((*data++) & 0xf) << 28;
*tlli |= (*data++) << 20;
*tlli |= (*data++) << 12;
*tlli |= (*data++) << 4;
*tlli |= (*data++) >> 4;
return 0;
}
int bts_rcv_imm_ass_cnf(struct gprs_rlcmac_bts *bts, const uint8_t *data, uint32_t tlli, uint32_t fn)
{
struct gprs_rlcmac_dl_tbf *dl_tbf;
GprsMs *ms;
int rc;
/* NOTE: A confirmation for a downlink IMMEDIATE ASSIGNMENT can be received using two different methods.
* One way is to send the whole IMMEDIATE ASSIGNMENT back to the PCU and the TLLI, which we use as
* reference is extracted from the rest octets of this message. Alternatively the TLLI may be sent as
* confirmation directly. */
/* Extract TLLI from the presented IMMEDIATE ASSIGNMENT
* (if present and only when TLLI that is supplied as function parameter is valid.) */
if (data && tlli == GSM_RESERVED_TMSI) {
rc = tlli_from_imm_ass(&tlli, data, fn);
if (rc != 0)
return -EINVAL;
}
/* Make sure TLLI is valid */
if (tlli == GSM_RESERVED_TMSI) {
LOGP(DTBFDL, LOGL_ERROR, "FN=%u Got IMM.ASS confirm, but TLLI is invalid!\n", fn);
return -EINVAL;
}
/* Find related TBF and send confirmation signal to FSM */
ms = bts_ms_by_tlli(bts, tlli, GSM_RESERVED_TMSI);
if (!ms) {
LOGP(DTBFDL, LOGL_ERROR, "FN=%u Got IMM.ASS confirm for unknown MS with TLLI=%08x\n", fn, tlli);

2
src/bts.h
View File

@ -315,7 +315,7 @@ int bts_tfi_find_free(const struct gprs_rlcmac_bts *bts, enum gprs_rlcmac_tbf_di
int bts_rcv_rach(struct gprs_rlcmac_bts *bts, const struct rach_ind_params *rip);
int bts_rcv_ptcch_rach(struct gprs_rlcmac_bts *bts, const struct rach_ind_params *rip);
int bts_rcv_imm_ass_cnf(struct gprs_rlcmac_bts *bts, const uint8_t *data, uint32_t fn);
int bts_rcv_imm_ass_cnf(struct gprs_rlcmac_bts *bts, const uint8_t *data, uint32_t tlli, uint32_t fn);
void bts_send_gsmtap(struct gprs_rlcmac_bts *bts,
enum pcu_gsmtap_category categ, bool uplink, uint8_t trx_no,

26
src/pcu_l1_if.cpp
View File

@ -512,7 +512,7 @@ static int pcu_rx_data_cnf(struct gprs_rlcmac_bts *bts, struct gsm_pcu_if_data *
switch (data_cnf->sapi) {
case PCU_IF_SAPI_PCH:
if (data_cnf->data[2] == GSM48_MT_RR_IMM_ASS)
bts_rcv_imm_ass_cnf(bts, data_cnf->data, data_cnf->fn);
bts_rcv_imm_ass_cnf(bts, data_cnf->data, GSM_RESERVED_TMSI, data_cnf->fn);
break;
default:
LOGP(DL1IF, LOGL_ERROR, "Received PCU data confirm with "
@ -523,6 +523,26 @@ static int pcu_rx_data_cnf(struct gprs_rlcmac_bts *bts, struct gsm_pcu_if_data *
return rc;
}
static int pcu_rx_data_cnf_dt(struct gprs_rlcmac_bts *bts, struct gsm_pcu_if_data_cnf_dt *data_cnf_dt)
{
int rc = 0;
int current_fn = bts_current_frame_number(bts);
LOGP(DL1IF, LOGL_DEBUG, "Data confirm received: sapi=%d fn=%d cur_fn=%d\n",
data_cnf_dt->sapi, data_cnf_dt->fn, current_fn);
switch (data_cnf_dt->sapi) {
case PCU_IF_SAPI_PCH:
bts_rcv_imm_ass_cnf(bts, NULL, data_cnf_dt->tlli, data_cnf_dt->fn);
break;
default:
LOGP(DL1IF, LOGL_ERROR, "Received PCU data confirm with unsupported sapi %d\n", data_cnf_dt->sapi);
rc = -EINVAL;
}
return rc;
}
// FIXME: remove this, when changed from c++ to c.
int pcu_rx_rts_req_pdtch(struct gprs_rlcmac_bts *bts, uint8_t trx, uint8_t ts,
uint32_t fn, uint8_t block_nr)
@ -1133,6 +1153,10 @@ int pcu_rx(struct gsm_pcu_if *pcu_prim, size_t pcu_prim_length)
CHECK_IF_MSG_SIZE(pcu_prim_length, pcu_prim->u.data_cnf);
rc = pcu_rx_data_cnf(bts, &pcu_prim->u.data_cnf);
break;
case PCU_IF_MSG_DATA_CNF_DT:
CHECK_IF_MSG_SIZE(pcu_prim_length, pcu_prim->u.data_cnf_dt);
rc = pcu_rx_data_cnf_dt(bts, &pcu_prim->u.data_cnf_dt);
break;
case PCU_IF_MSG_RTS_REQ:
CHECK_IF_MSG_SIZE(pcu_prim_length, pcu_prim->u.rts_req);
rc = pcu_rx_rts_req(bts, &pcu_prim->u.rts_req);