From 9bffa87c1195d2977d49244fbc3e3c0c9b65c318 Mon Sep 17 00:00:00 2001 From: Stefan Sperling Date: Thu, 9 Aug 2018 20:14:19 +0200 Subject: send TCH/F fill frames in DTX mode (WIP) Send DTX TCH fill frames according to GSM 05.08, section 8.3. Change-Id: I7bff00b8cf41dc1b0e6e668173bebce23be0d253 Related: OS#1950 --- src/common/l1sap.c | 77 +++++++++++++++++++++++++++++++++++++++++++++--------- 1 file changed, 64 insertions(+), 13 deletions(-) (limited to 'src/common/l1sap.c') diff --git a/src/common/l1sap.c b/src/common/l1sap.c index b8cec0e7..5cc303b8 100644 --- a/src/common/l1sap.c +++ b/src/common/l1sap.c @@ -666,6 +666,31 @@ static int lchan_pdtch_ph_rts_ind_loop(struct gsm_lchan *lchan, return 0; } + /* Determine whether we need to send a DTX TCH fill frame according to GSM 05.08, section 8.3. */ +static bool is_required_tchf_fill_frame_dtx(uint32_t fn, struct gsm_time *g_time) { + /* On TCHF this subset of TDMA frames (mod 104) is always used for transmission during DTX: */ + const int tchf_required_fn_dtx[] = { 52, 53, 54, 55, 56, 57, 58, 59 }; + /* And the subset of those frames which corresponds to a TCH/F block boundary, + * which is the level at which L1SAP operates: */ + const int tchf_required_block_fn_dtx[] = { 52, 56 }; + int i; + + for (i = 0; i < ARRAY_SIZE(tchf_required_block_fn_dtx); i++) { + if (fn % 104 == tchf_required_block_fn_dtx[i]) + return true; + } + + /* We should only see block-level frame numbers here. Log a warning otherwise. */ + for (i = 0; i < ARRAY_SIZE(tchf_required_fn_dtx); i++) { + if (fn % 104 == tchf_required_fn_dtx[i]) + LOGPGT(DL1P, LOGL_NOTICE, g_time, + "Unexpected TCH/F frame number received in RTS.IND " + "(not at TCH/F block boundary): %u (mod 104: %u)\n", fn, fn % 104); + } + + return false; +} + /* PH-RTS-IND prim received from bts model */ static int l1sap_ph_rts_ind(struct gsm_bts_trx *trx, struct osmo_phsap_prim *l1sap, struct ph_data_param *rts_ind) @@ -725,14 +750,18 @@ static int l1sap_ph_rts_ind(struct gsm_bts_trx *trx, si = bts_sysinfo_get(trx->bts, &g_time); if (si) memcpy(p, si, GSM_MACBLOCK_LEN); - else + else { memcpy(p, fill_frame, GSM_MACBLOCK_LEN); + DEBUGPGT(DL1P, &g_time, "sending fill frame BCCH chan_nr=%d fn=%u\n", chan_nr, fn); + } } else if (!(chan_nr & 0x80)) { /* only TCH/F, TCH/H, SDCCH/4 and SDCCH/8 have C5 bit cleared */ + bool dtxd = false; lchan = get_active_lchan_by_chan_nr(trx, chan_nr); if (!lchan) { LOGPGT(DL1P, LOGL_ERROR, &g_time, "No lchan for PH-RTS.ind (chan_nr=%u)\n", chan_nr); return 0; } + dtxd = lchan->ts->trx->bts->dtxd; if (L1SAP_IS_LINK_SACCH(link_id)) { p = msgb_put(msg, GSM_MACBLOCK_LEN); /* L1-header, if not set/modified by layer 1 */ @@ -752,20 +781,39 @@ static int l1sap_ph_rts_ind(struct gsm_bts_trx *trx, if (si) { /* The +2 is empty space where the DSP inserts the L1 hdr */ memcpy(p + 2, si, GSM_MACBLOCK_LEN - 2); - } else + } else { memcpy(p + 2, fill_frame, GSM_MACBLOCK_LEN - 2); - } else if (L1SAP_IS_CHAN_SDCCH4(chan_nr) || L1SAP_IS_CHAN_SDCCH8(chan_nr) || - (lchan->rsl_cmode == RSL_CMOD_SPD_SIGN && !lchan->ts->trx->bts->dtxd)) { - /* - * SDCCH or TCH in signalling mode without DTX. - * - * Send fill frame according to GSM 05.08, section 8.3: "On the SDCCH and on the - * half rate speech traffic channel in signalling only mode DTX is not allowed. - * In these cases and during signalling on the TCH when DTX is not used, the same - * L2 fill frame shall be transmitted in case there is nothing else to transmit." - */ + DEBUGPGT(DL1P, &g_time, "sending fill frame SACCH chan_nr=%d fn=%u dtx=%s\n", chan_nr, fn, dtxd ? "enabled" : "disabled"); + } + } else if (L1SAP_IS_CHAN_SDCCH4(chan_nr) || L1SAP_IS_CHAN_SDCCH8(chan_nr)) { p = msgb_put(msg, GSM_MACBLOCK_LEN); memcpy(p, fill_frame, GSM_MACBLOCK_LEN); + DEBUGPGT(DL1P, &g_time, "sending fill frame SDCCH chan_nr=%d fn=%u dtx=%s\n", chan_nr, fn, dtxd ? "enabled" : "disabled"); + } else if (lchan->rsl_cmode == RSL_CMOD_SPD_SIGN) { + if (dtxd_facch) { + /* + * TCH in signalling mode with DTX. + * Send fill frame according to GSM 05.08, section 8.3. + */ + if (L1SAP_IS_CHAN_TCHF(chan_nr) && is_required_tchf_fill_frame_dtx(fn, &g_time)) { + p = msgb_put(msg, GSM_MACBLOCK_LEN); + memcpy(p, fill_frame, GSM_MACBLOCK_LEN); + DEBUGPGT(DL1P, &g_time, "sending fill frame TCH chan_nr=%d fn=%u dtx=%s\n", chan_nr, fn, dtxd ? "enabled" : "disabled"); + //dtx_dispatch(lchan, E_FACCH); /* XXX is this needed? */ + } + } else { + /* + * TCH in signalling mode without DTX. + * + * Send fill frame according to GSM 05.08, section 8.3: "On the SDCCH and on the + * half rate speech traffic channel in signalling only mode DTX is not allowed. + * In these cases and during signalling on the TCH when DTX is not used, the same + * L2 fill frame shall be transmitted in case there is nothing else to transmit." + */ + p = msgb_put(msg, GSM_MACBLOCK_LEN); + memcpy(p, fill_frame, GSM_MACBLOCK_LEN); + DEBUGPGT(DL1P, &g_time, "sending fill frame TCH chan_nr=%d fn=%u dtx=%s\n", chan_nr, fn, dtxd ? "enabled" : "disabled"); + } } /* else the message remains empty, so TCH frames are sent */ } else { /* The +2 is empty space where the DSP inserts the L1 hdr */ @@ -786,8 +834,10 @@ static int l1sap_ph_rts_ind(struct gsm_bts_trx *trx, rc = bts_ccch_copy_msg(trx->bts, p, &g_time, (L1SAP_FN2CCCHBLOCK(fn) < num_agch(trx, "PH-RTS-IND"))); - if (rc <= 0) + if (rc <= 0) { memcpy(p, fill_frame, GSM_MACBLOCK_LEN); + DEBUGPGT(DL1P, &g_time, "sending fill frame AGCH PCH chan_nr=%d fn=%u\n", chan_nr, fn); + } } DEBUGPGT(DL1P, &g_time, "Tx PH-DATA.req chan_nr=0x%02x link_id=0x%02x\n", chan_nr, link_id); @@ -1436,6 +1486,7 @@ int l1sap_chan_act(struct gsm_bts_trx *trx, uint8_t chan_nr, struct tlv_parsed * char name[32]; snprintf(name, sizeof(name), "bts%u-trx%u-ts%u-ss%u", lchan->ts->trx->bts->nr, lchan->ts->trx->nr, lchan->ts->nr, lchan->nr); + LOGP(DL1C, LOGL_NOTICE, "allocating DTX FSM for chan_nr=%d\n", chan_nr); lchan->tch.dtx.dl_amr_fsm = osmo_fsm_inst_alloc(&dtx_dl_amr_fsm, tall_bts_ctx, lchan, -- cgit v1.2.3