dexter has submitted this change. ( https://gerrit.osmocom.org/c/osmo-pcu/+/31145 ) Change subject: bts: add IMMEDIATE ASSIGNMENT via PCH transmission ...................................................................... bts: add IMMEDIATE ASSIGNMENT via PCH transmission In situations where the PCU is co-located to the BSC, the IMMEDIATE ASSIGNMENT for downlink TBFs must be sent via RSL and the BSC also must instruct the BTS to transmit the IMMEDIATE ASSIGNMENT via PCH instead of AGCH. Eventually the BSC must sent a confirmation message (follow-up patch) where the TLLI is used as an identifer. This new method will eventually replace the previous method that uses the MAC block as an identifier. To remain compatible with older versions of osmo-bsc, we will keep the old method until osmo-bts is migrated as well. This patch also requires new features to be added to the PCU socket interface the version number of the protocol is incremented from 0x0a to 0x0b. Version 0x0a will remain compatible and use the old method, while version 0x0b will use the new method introduced with this patch. Change-Id: I2a78651593323e8b9627c39918d949a33497b70f Related: OS#5198 --- M include/osmocom/pcu/pcuif_proto.h M src/bts.cpp M src/gprs_pcu.h M src/pcu_l1_if.cpp M src/pcu_l1_if.h 5 files changed, 77 insertions(+), 7 deletions(-) Approvals: Jenkins Builder: Verified pespin: Looks good to me, but someone else must approve laforge: Looks good to me, approved diff --git a/include/osmocom/pcu/pcuif_proto.h b/include/osmocom/pcu/pcuif_proto.h index 693a1d5..1dda160 100644 --- a/include/osmocom/pcu/pcuif_proto.h +++ b/include/osmocom/pcu/pcuif_proto.h @@ -3,10 +3,12 @@ #include <osmocom/gsm/l1sap.h> #include <arpa/inet.h> +#include <osmocom/gsm/protocol/gsm_04_08.h> +#include <osmocom/gsm/protocol/gsm_23_003.h> #define PCU_SOCK_DEFAULT "/tmp/pcu_bts" -#define PCU_IF_VERSION 0x0a +#define PCU_IF_VERSION 0x0b #define TXT_MAX_LEN 128 /* msg_type */ @@ -269,6 +271,17 @@ } cgi_ps; } __attribute__ ((packed)); +/* Struct to send a (confirmed) IMMEDIATE ASSIGNMENT message via PCH. The struct is sent as a data request + * (data_req) under SAPI PCU_IF_SAPI_PCH_DT. */ +struct gsm_pcu_if_pch_dt { + /* TLLI as reference for confirmation */ + uint32_t tlli; + /* IMSI (to derive paging group) */ + char imsi[OSMO_IMSI_BUF_SIZE]; + /* GSM mac-block (with immediate assignment message) */ + uint8_t data[GSM_MACBLOCK_LEN]; +} __attribute__((packed)); + struct gsm_pcu_if { /* context based information */ uint8_t msg_type; /* message type */ diff --git a/src/bts.cpp b/src/bts.cpp index 33ad4a6..504ba27 100644 --- a/src/bts.cpp +++ b/src/bts.cpp @@ -1103,7 +1103,6 @@ void bts_snd_dl_ass(struct gprs_rlcmac_bts *bts, const struct gprs_rlcmac_dl_tbf *tbf) { - uint16_t pgroup = ms_paging_group(tbf_ms(tbf)); int plen; const struct gprs_rlcmac_pdch *pdch; @@ -1129,7 +1128,10 @@ GSM_L1_BURST_TYPE_ACCESS_0); if (plen >= 0) { bts_do_rate_ctr_inc(bts, CTR_IMMEDIATE_ASSIGN_DL_TBF); - pcu_l1if_tx_pch(bts, immediate_assignment, plen, pgroup); + if (the_pcu->pcu_if_version >= 0x0b) + pcu_l1if_tx_pch_dt(bts, immediate_assignment, plen, tbf->imsi(), tbf->tlli()); + else + pcu_l1if_tx_pch(bts, immediate_assignment, plen, ms_paging_group(tbf_ms(tbf))); } bitvec_free(immediate_assignment); diff --git a/src/gprs_pcu.h b/src/gprs_pcu.h index a9e40ea..ca52c30 100644 --- a/src/gprs_pcu.h +++ b/src/gprs_pcu.h @@ -134,6 +134,8 @@ struct si_cache *si_cache; /* ARFC+BSIC -> CGI PS cache */ struct osmo_timer_list update_stats_timer; /* Used to update some time_cc stats periodically */ + + uint8_t pcu_if_version; }; diff --git a/src/pcu_l1_if.cpp b/src/pcu_l1_if.cpp index 6c4ed22..14cc778 100644 --- a/src/pcu_l1_if.cpp +++ b/src/pcu_l1_if.cpp @@ -294,6 +294,24 @@ pcu_tx_data_req(bts, 0, 0, PCU_IF_SAPI_PCH, 0, 0, 0, data, sizeof(data)); } +/* Send a block via the paging channel and require a confirmation by the receiving end */ +void pcu_l1if_tx_pch_dt(struct gprs_rlcmac_bts *bts, bitvec *block, int plen, const char *imsi, uint32_t tlli) +{ + /* NOTE: This is in practice only used to transmit IMMEDIATE ASSIGNMENT messages through the paging channel and + * it is not guaranteed to work with other message types. The prepended TLLI will be used as an identifier in + * the confirmation message. */ + + struct gsm_pcu_if_pch_dt pch_dt; + + pch_dt.tlli = tlli; + strcpy(pch_dt.imsi, imsi); + + pch_dt.data[0] = (plen << 2) | 0x01; + bitvec_pack(block, pch_dt.data + 1); + + pcu_tx_data_req(bts, 0, 0, PCU_IF_SAPI_PCH_DT, 0, 0, 0, (uint8_t*)&pch_dt, sizeof(pch_dt)); +} + int pcu_tx_neigh_addr_res_req(struct gprs_rlcmac_bts *bts, const struct neigh_cache_entry_key *neigh_key) { struct msgb *msg; @@ -734,14 +752,22 @@ if (llist_count(&the_pcu->bts_list) > 1) LOGP(DL1IF, LOGL_ERROR, "more than one BTS regsitered at this PCU. This PCU has only been tested with one BTS! OS#5930\n"); - if (info_ind->version != PCU_IF_VERSION) { - fprintf(stderr, "PCU interface version number of BTS (%u) is " - "different (%u).\nPlease re-compile!\n", + LOGP(DL1IF, LOGL_DEBUG, "Info indication received:\n"); + + /* NOTE: The classic way to confirm an IMMEDIATE assignment is to send the whole MAC block payload back to the + * PCU. So it is the MAC block itsself that serves a reference for the confirmation. This method has certain + * disadvantages so it was replaced with a method that uses the TLLI as a reference ("Direct TLLI"). This new + * method will replace the old one. The code that handles the old method will be removed in the foreseeable + * future. (see also OS#5927) */ + if (info_ind->version == 0x0a) { + LOGP(DL1IF, LOGL_NOTICE, "PCUIF version 10 is deprecated. OS#5927\n"); + } else if (info_ind->version != PCU_IF_VERSION) { + fprintf(stderr, "PCU interface version number of BTS/BSC (%u) is different (%u).\nPlease use a BTS/BSC with a compatble interface!\n", info_ind->version, PCU_IF_VERSION); exit(-1); } - LOGP(DL1IF, LOGL_DEBUG, "Info indication received:\n"); + the_pcu->pcu_if_version = info_ind->version; if (!(info_ind->flags & PCU_IF_FLAG_ACTIVE)) { LOGP(DL1IF, LOGL_NOTICE, "BTS not available\n"); diff --git a/src/pcu_l1_if.h b/src/pcu_l1_if.h index e7080d5..1827d84 100644 --- a/src/pcu_l1_if.h +++ b/src/pcu_l1_if.h @@ -149,6 +149,7 @@ void pcu_l1if_tx_agch(struct gprs_rlcmac_bts *bts, bitvec *block, int len); void pcu_l1if_tx_pch(struct gprs_rlcmac_bts *bts, bitvec *block, int plen, uint16_t pgroup); +void pcu_l1if_tx_pch_dt(struct gprs_rlcmac_bts *bts, bitvec *block, int plen, const char *imsi, uint32_t tlli); #endif #ifdef __cplusplus -- To view, visit https://gerrit.osmocom.org/c/osmo-pcu/+/31145 To unsubscribe, or for help writing mail filters, visit https://gerrit.osmocom.org/settings Gerrit-Project: osmo-pcu Gerrit-Branch: master Gerrit-Change-Id: I2a78651593323e8b9627c39918d949a33497b70f Gerrit-Change-Number: 31145 Gerrit-PatchSet: 24 Gerrit-Owner: dexter &lt;pmaier(a)sysmocom.de&gt; Gerrit-Reviewer: Jenkins Builder Gerrit-Reviewer: dexter &lt;pmaier(a)sysmocom.de&gt; Gerrit-Reviewer: fixeria &lt;vyanitskiy(a)sysmocom.de&gt; Gerrit-Reviewer: laforge &lt;laforge(a)osmocom.org&gt; Gerrit-Reviewer: pespin &lt;pespin(a)sysmocom.de&gt; Gerrit-CC: neels &lt;nhofmeyr(a)sysmocom.de&gt; Gerrit-MessageType: merged