IPV6 support for telnet socket binding
Now, the listening telnet socket is only bound to the dedicated interface IPs in
config file, both for V4 and V6
Closes#834
Fix handling of IPv4v6 PDU sessions
The code previously checked that the supplied PDU sessions's type is
exactly what we requested. However, at least OAI 5GC will only give us
an IPv4 PDU session if we request IPv4v6 (so the check would fail).
Extend the validation to either check exact match, or, if IPv4v6
requested, that it is either IPv4 or IPv6.
fix: removed the nssai_sd parameter in the ue.conf file
Following the tutorial in the RF simulator, the PDU session cannot
be established because the Slice Differentiator to request(nssai_sd)
parameter in the ue.conf file is 1(integer) but in the documentation
the default value of the nssai_sd is 0xFFFFF(meaning "no SD")
Now the nssai_sd parameter is removed in the ue.conf to establish the
PDU session.
NR UE: correctly compute writeTimestamp for SCS > 30 kHz with rf-simulator
Contains also two minor cleanups for nr-ue.c:
- make fp point to constant NR_DL_FRAME_PARMS where possible
- use c16_t type for I/Q sample arrays
print better message for rsrp: invalid doesn't mean it is not measured
print better message for rsrp: invalid doesn't mean it is not measured,
it means it is out of usable range
NR UE: fix PRACH k1 calculation at MAC when handover
The k1 for PRACH calculation in config_common_ue() should be the same as in
config_common_ue_sa(), otherwise k1 is wrong when handover to target cell if
msg1-FDM not 0 in reconfigurationWithSync.
Verified with 3rd-party gNB.
The code previously checked that the supplied PDU sessions's type is
exactly what we requested. However, at least OAI 5GC will only give us
an IPv4 PDU session if we request IPv4v6 (so the check would fail).
Extend the validation to either check exact match, or, if IPv4v6
requested, that it is either IPv4 or IPv6.
Following the tutorial in the RF simulator, the PDU session cannot
be established because the Slice Differentiator to request(nssai_sd)
parameter in the ue.conf file is 1(integer) but in the documentation
the default value of the nssai_sd is 0xFFFFF(meaning "no SD")
Now the nssai_sd parameter is removed in the ue.conf to establish the
PDU session.
gNB: Reset NDI only after usage in case of disable HARQ
Solves this warnings seen in the UE trace:
NDI indicates re-transmission but computed TBS 3968 doesn't match with what previously stored 3368
Issue happens only if feature disable_harq is enabled. GNB resets the harq
process (including NDI) as PUCCH will not be sent for this harq process, but
before the harq process is used in DCI payload preparation.
Fix is to reset the harq process after harq process in case of no PUCCH.
Fail early if configuration module can not initialize properly
In the case that the config module cannot load the driver for libconfig or yaml,
currently, there might be a cascade of errors that are difficult for users to
understand. For instance (partially redacted for clarity):
[CONFIG] Error calling dlopen(libparams_libconfig.so): libparams_libconfig.so: cannot open shared object file: No such file or directory
[CONFIG] config module "libconfig" couldn't be loaded
[CONFIG] config_get, section log_config skipped, config module not properly initialized
[LOG] init aborted, configuration couldn't be performed
[CONFIG] config_get, section (null) skipped, config module not properly initialized
[CONFIG] /home/francesco/openairinterface5g/common/config/config_userapi.c 68 nfapi has no processed integer availablle
[CONFIG] config_get, section (null) skipped, config module not properly initialized
Assertion (get_softmodem_params()->default_pdu_session_id == -1) failed!
In get_common_options() /home/francesco/openairinterface5g/executables/softmodem-common.c:161
Use uicc0.pdu_sessions.[0].id to change the requested PDU session ID (is 0)
Here, the error is the missing shared object, but a user is more likely to look
at the last error instead of the first.
This commit addresses it by checking early for CONFIG_ISFLAGSET(CONFIG_ABORT),
and stopping if it is set. Additionally changes include making functions static,
removing late CONFIG_ISFLAGSET() checks, and the CONFIG_ISFLAGSET() in
load_configmodule(), because at that time "uniqCfg" is not set yet and thus does
not do anything (this is likely a regression of an earlier cleanup).
See-also: f50d5f5a ("make multiple config instead of one implicit global")
Integration: `2026.w08`
* !3934 Fix Ubuntu build: reinstate -Werror
* !3803 remove cblas and atlas dependancy
* !3918 Add a simple GTP unit test
* !3924 T: macpdu2wireshark: gentle exit (and some other minor work in the T tracer)
* !3925 Fix race condition on double RA during RRC reestablishment
* !3930 bugfix: add PCell to serving_cells in fallback path and refactor update logic
* !3936 [FHI72] Remove support for xran E release
* !3893 NR Paging on CU
See merge request oai/openairinterface5g!3939
In the case that the config module cannot load the driver for libconfig
or yaml, currently, there might be a cascade of errors that are
difficult for users to understand. For instance (partially redacted for
clarity):
[CONFIG] Error calling dlopen(libparams_libconfig.so): libparams_libconfig.so: cannot open shared object file: No such file or directory
[CONFIG] config module "libconfig" couldn't be loaded
[CONFIG] config_get, section log_config skipped, config module not properly initialized
[LOG] init aborted, configuration couldn't be performed
[CONFIG] config_get, section (null) skipped, config module not properly initialized
[CONFIG] /home/francesco/openairinterface5g/common/config/config_userapi.c 68 nfapi has no processed integer availablle
[CONFIG] config_get, section (null) skipped, config module not properly initialized
Assertion (get_softmodem_params()->default_pdu_session_id == -1) failed!
In get_common_options() /home/francesco/openairinterface5g/executables/softmodem-common.c:161
Use uicc0.pdu_sessions.[0].id to change the requested PDU session ID (is 0)
Here, the error is the missing shared object, but a user is more likely
to look at the last error instead of the first.
This commit addresses it by checking early for
CONFIG_ISFLAGSET(CONFIG_ABORT), and stopping if it is set. Additionally
changes include making functions static, removing late
CONFIG_ISFLAGSET() checks, and the CONFIG_ISFLAGSET() in
load_configmodule(), because at that time "uniqCfg" is not set yet and
thus does not do anything (this is likely a regression of an earlier
cleanup).
See-also: f50d5f5a9b ("make multiple config instead of one implicit
global")
NR Paging on CU
Implements the NR paging path on the CU:
- NGAP Paging is decoded and passed to RRC
- RRC builds F1AP Paging, and distributes it to DUs via F1 callback
Changes:
- Refactor and extend F1AP Paging encode/decode libraries
* add missing enc/dec/eq/cp functions
* add unit test
* IEs: CN UE 5G-S-TMSI, RAN UE I-RNTI; optional DRX/priority/origin)
- Refactor CU callback CU_send_Paging
- Refactor DU handler DU_handle_Paging
- Refactor old F1 callback for Paging indication, extend it and align
with existing F1 callbacks in stack
- Refactor and extend NGAP Paging encode/decode lib
* add missing enc/dec/eq/cp functions
* add unit test
* Fixes NGAP paging to accept Paging only on SCTP stream 0 per TS
38.412
- Includes supporting refactors (PDU session split, shared 5G-S-TMSI
helpers, NGAP/F1AP cleanups)
Testing
- NGAP and F1AP Paging lib unit tests (enc/dec)
- Stream-0 fix validated with Open5GS AMF
This MR does not address the DU changes besides the F1 handler. F1AP
Paging does not have an RRC container to pass the PCCH message to the
DU, and F1 DL RRC Message Transfer does not apply to PCCH. PCCH-Message
shall be built at DU per TS 38.331 §5.3.2, with padding as per §8.5 and
delivered as RLC SDU per §8.2. For each cell in Paging Cell List that
belongs to this DU, queue for MAC. MAC schedules at PF/PO per TS 38.304
§7.
Refs:
- F1AP 3GPP TS 38.473 version 16.21.0 Release 16
- NGAP 3GPP TS 38.413 version 16.17.0 Release 16
[FHI72] Remove support for xran E release
All the use cases we tested with E release are working end-to-end with F release.
The near future plan is to support K release which is ongoing in the MR !3444.
bugfix: add PCell to serving_cells in fallback path and refactor update logic
Fix assertion failure in rrc_gNB_send_NGAP_NAS_FIRST_REQ() when RRC
Reestablishment falls back to RRC Setup. The fallback path was not
adding the PCell to the UE's serving_cells array, causing
rrc_get_pcell_for_ue() to return NULL.
Major changes:
- Add rrc_update_ue_pcell() helper function that handles PCell updates
for both new UEs (fallback) and existing UEs (normal reestablishment)
- Refactor normal reestablishment path to use rrc_update_ue_pcell()
helper instead of manual cleanup + add sequence
- Add PCell update to fallback_rrc_setup path using the same helper
- Move C-RNTI validation after current_cell fetch to ensure current_cell
is initialized before fallback_rrc_setup label
- Change error handling: return instead of fallback when PCell add fails
in normal reestablishment path
Fixes CI failure in !3908
All the use cases we tested so far, are supported with xran F release.
Therefore, we can proceed with removing the support with E release.
In addition, our plan is to bring the support for K release which is ongoing activity in
the MR https://gitlab.eurecom.fr/oai/openairinterface5g/-/merge_requests/3444.
Fix race condition on double RA during RRC reestablishment
Sometimes, especially in poor channel conditions, a UE can trigger
multiple RA procedures during RRC reestablishment, causing
reconfigCellGroup to be overwritten with a CellGroup that already has
spCellConfig removed, leading to an assertion failure in
update_cellgroup_for_reestablishment(). See logs below
[NR_MAC] 456.13 UE 991d: Received Ack of Msg4. CBRA procedure succeeded (UE Connected)
[NR_MAC] Adding new UE context with RNTI 0x991d
[NR_PHY] [RAPROC] 461.9 Initiating RA procedure with preamble 8, energy 48.0 dB (I0 274, thres 130), delay 21 start symbol 2 freq index 0
[NR_MAC] 461.9 UE RA-RNTI 0081 TC-RNTI ecd8: initiating RA procedure
[NR_MAC] UE ecd8: Sync beam index 0
[NR_MAC] UE ecd8: Msg3 scheduled at 462.3 (461.18 TDA 2) start 0 RBs 8
[NR_MAC] UE ecd8: 461.18 Generating RA-Msg2 DCI, RA RNTI 0x81, state 1, preamble_index(RAPID) 8, timing_offset = 21 (estimated distance 820.3 [m])
[NR_MAC] 462. 3 PUSCH with TC_RNTI 0xecd8 received correctly
[NR_MAC] Received a MAC CE for C-RNTI with 991d
[NR_MAC] Remove NR rnti 0xecd8
[NR_MAC] 462. 3 RA with C-RNTI 991d complete
[NR_PHY] [RAPROC] 471.19 Initiating RA procedure with preamble 6, energy 51.0 dB (I0 276, thres 130), delay 21 start symbol 2 freq index 0
[NR_MAC] 471.19 UE RA-RNTI 010d TC-RNTI 022d: initiating RA procedure
[NR_MAC] UE 022d: Sync beam index 0
[NR_MAC] UE 022d: Msg3 scheduled at 472.13 (472.8 TDA 2) start 0 RBs 8
[NR_MAC] UE 022d: 472.8 Generating RA-Msg2 DCI, RA RNTI 0x10d, state 1, preamble_index(RAPID) 6, timing_offset = 21 (estimated distance 820.3 [m])
[NR_MAC] 472.13 PUSCH with TC_RNTI 0x022d received correctly
[NR_MAC] Received a MAC CE for C-RNTI with 991d
[NR_MAC] Remove NR rnti 0x022d
[NR_MAC] 472.13 RA with C-RNTI 991d complete
[NR_RRC] [UL] (cellID 1, UE ID 1 RNTI 991d) Received RRCReestablishmentComplete
[NR_RRC] UE 1 Processing NR_RRCReestablishmentComplete from UE
[NR_MAC] UE 991d: gNB-DU Configuration Query received, will include CellGroupConfig in response
Assertion (new_CellGroup->spCellConfig) failed!
In update_cellgroup_for_reestablishment() /phy/openairinterface5g/openair2/LAYER2/NR_MAC_gNB/mac_rrc_dl_handler.c:666
This MR solves it by skipping the reconfigCellGroup overwrite when it
already holds a valid config with spCellConfig, and by replacing the
fatal assertion on missing spCellConfig with an early return.
T: macpdu2wireshark: gentle exit (and some other minor work in the T tracer)
When outputting to a file, typing ctrl+c exits the program without
calling fclose(), leading to loss of traces in the output file.
Let's intercept ctrl+c and exit gently, calling fclose().
Also include a small fix for compilation of _check_vcd, some work on
extract and hacks/plot-ofdm, minor stuff.
Add a simple GTP unit test
Add a simple unit test for GTP that as of now tests the main
functionality, i.e., for a single UE, set up a bearer between two
endpoints and checking that traffic sending works. This is a start to
extend it further, e.g., with API changes, extensions to support new
functionality such as IPv6, and refactorings.
A number of supporting cleanup has been done as well.
remove cblas and atlas dependancy
With new Fedora, we have again the cblas.h place not working
cblas+atlas dependancy is annoying for years
i start this MR to remove this dependancy
first commit: only cleaning: remove dead code, make static functions,
simplify code
after this commit, we see we use blas only in: conjugate_transpose()
that is a quite trivial function H_hermH_plus_sigma2I() a bit more
complex, but still possible to recode mutl_matrix_matrix_col_based() i
think we have the same elsewhere in OAI
atlas is used only in: lin_eq_solver() in don't know if replacement is
hard
We can observe all is related to MMSE, that is also coded in OAI 5G, so
maybe the solution is to use 5G code in 4G
Since nothing seems to be used, we can remove it.
The k1 for PRACH calculation in config_common_ue() should be the same as in config_common_ue_sa(),
otherwise k1 is wrong when handover to target cell if msg1-FDM not 0 in reconfigurationWithSync.
For unit testing, allow to remove endpoints such that we could reuse a
port/IP combination.
The function does not take care of endpoints that are still "dangling",
it is the user's responsibility to remove all existing TEIDs.
Add a simple unit test that tests sending unidirectional traffic. So
far, it merely replicates what is already in nr-cuup-load-test, but it's
a single executable (so easier to handle), and could be more easily
extended to further tests (e.g., IPv6).
A couple of ideas for refactoring/improvements have been added in
comments in the test.
Paging messages are classified as non-UE-associated signalling per
3GPP TS 38.412 clause 7 (TL), which requires them to be sent on
stream 0 (or a reserved stream pair).
Paging message is received when UE is in RRC_IDLE or RRC_INACTIVE
state, as the RAN has no active UE context and paging targets the
UE by 5G-S-TMSI rather than RAN-UE-NGAP-ID.
The previous implementation incorrectly rejected paging messages
received on stream 0, causing paging failures when using Open5GS AMF.
Changes:
- Accept paging on stream 0 (non-UE-associated signalling)
- Reject paging on non-zero streams (UE-associated streams)
- Add documentation
RRC now builds F1AP paging messages directly by calling F1AP/direct
callbacks and aligning the CU/DU intergace with the F1AP design in the CU.
Messages are forwarded based on TAI-based cell matching across DUs.
- Remove F1AP_PAGING_IND message def and f1ap_paging_ind_t.
RRC no longer sends ITTI F1AP_PAGING_IND; it builds f1ap_paging_t
and passes it to the DU path.
- rrc_gNB_process_PAGING_IND: new signature (rrc, instance, msg)
with const where appropriate; call in rrc_gnb_task() updated.
- NGAP handler logic: For each TAI, match (PLMN + TAC) to
rrc->configuration; collect matching TAIs. Build one f1ap_paging_t
(5G-S-TMSI via nr_construct_5g_s_tmsi(), identity type
F1AP_PAGING_IDENTITY_CN_UE, optional drx/priority/origin copied
from ngap_paging_ind_t), call rrc_send_paging_to_dus(), then
free_f1ap_paging(). Remove the previous AssertFatal stub, CC loop,
NODE_IS_CU branch, and UE lookup logic: it is now handled by
F1AP/direct CU callbacks.
- rrc_gNB_du: Add rrc_send_paging_to_dus(rrc, tais, n_tai, msg).
Iterate DUs with RB_FOREACH; for each DU, fill msg->cells from
du->cells whose (PLMN + TAC) matches any requested TAI, set
n_cells, then call rrc->mac_rrc.paging_transfer(du->assoc_id,
msg). Skip DUs with no matching cells. Prevents duplicate paging
when multiple TAIs map to the same PLMN.
Introduce paging_transfer in the mac_rrc_dl interface so the CU can pass
paging to the DU (F1 or direct). Use the F1AP paging lib on both CU and DU
for decode/free and to avoid leaking the message after send.
- Add f1_paging_transfer_func_t and paging_transfer to nr_mac_rrc_dl_if_s
(mac_rrc_dl.h, nr_rrc_defs.h).
- F1AP path: paging_f1ap() allocates F1AP_PAGING, copies with cp_f1ap_paging(),
sends via ITTI to TASK_CU_F1. Direct path: f1_paging_transfer_direct() stub
- CU task: call free_f1ap_paging() after CU_send_Paging() to release the message.
- DU: DU_handle_Paging() uses decode_f1ap_paging()/free_f1ap_paging() from lib,
returns on decode failure; remove inline ASN.1 IE parsing.
- cleanup outdated header comments in header files
- Left a TODO not in DU code to build PCCH (in F1 and direct paths)
- Add F1AP_PAGING message type and macro; F1AP defines Paging, not
Paging Indication. CU task now handles F1AP_PAGING instead of
F1AP_PAGING_IND.
- In CU_send_Paging(): take const f1ap_paging_t *; replace inline
ASN.1 encoding with encode_f1ap_paging(); refine memory management;
clean up in the process
Note: F1AP_PAGING_IND definitions left in place and still used in the
RRC callback - to be removed in a follow-up commit.
Add F1AP Paging library and new message type to follow the existing F1AP
library pattern and to support multi-cell paging and both RAN UE (I-RNTI)
and CN UE (5G-S-TMSI) paging identities at the library level per TS 38.473.
* New library (f1ap_paging.c/h, f1ap_lib_includes.h, CMakeLists.txt)
- Implement encode/decode/copy/eq/free for F1AP Paging (procedure 9.2.6).
- Add ASN.1 includes for Paging, PagingIdentity, CN/RAN UE identities.
- Enables unit testing of Paging enc/dec in f1ap_lib_test.c.
* New types in f1ap_messages_types.h (existing f1ap_paging_ind_t unchanged)
- f1ap_paging_t: UE Identity Index, paging identity (union + type enum),
optional paging_drx, paging_priority, paging_origin, and paging_cells[].
- f1ap_paging_cell_item_t, f1ap_paging_identity_type_t, f1ap_paging_identity_t
for multi-cell list and RAN/CN identity discrimination.
- Paging Origin IE is optional per F1AP 8.7.1.2.
Tests: test_f1ap_paging() roundtrip and copy for CN UE (5G-S-TMSI) and
RAN UE (I-RNTI) cases, with optional IEs.
- Refactor ngap_paging_ind_t (openair2/COMMON/ngap_messages_types.h):
- optional paging_drx and paging_priority as pointers
- TAI list as tai_list[] and n_tai
- add optional IEs: Paging Origin, Paging Attempt Information,
UE Radio Capability for Paging.
- Introduce nr_tai_t, ngap_paging_attempt_info_t, ngap_paging_origin_t;
- generate paging enums via FOREACH macros.
- Add NGAP Paging encode/decode/eq/free in openair3/NGAP/ngap_gNB_paging.c
(encode_ng_paging, decode_ng_paging, eq_ng_paging, free_ng_paging).
- Replace inline Paging decode in ngap_gNB_handle_paging() with
decode_ng_paging() and add error handling; add eq_ngap_plmn() in
ngap_common.
- Update rrc_gNB_NGAP.c to use tai_list/n_tai and optional paging_drx
when forwarding paging to F1AP.
- Add ASN.1 includes for Paging in ngap_msg_includes.h; register
ngap_gNB_paging.c in root CMakeLists.txt.
- Add NGAP unit test (openair3/NGAP/tests/ngap_lib_test.c): encode/decode
roundtrip for Paging; tests subdirectory and executable under
ENABLE_TESTS in openair3/NGAP/CMakeLists.txt.
ngap_common.h is for common IEs enc/dec functions, utilities
should go into a separate file. Changes in this commit:
* Add ngap_utils.h (utilities)
* Move helper macros (NGAP_ERROR, NGAP_DEBUG, NGAP_FIND_PROTOCOLIE_BY_ID, etc.) to ngap_utils.h
* Move equality check macros (_NGAP_EQ_CHECK_*) to ngap_utils.h
* Clean up includes
This change is preparatory to the introduction the paging lib with unit
tests, with the goal of reducing the inter-dependency between concurrent
NGAP libs.
TO_ENUM/TO_TEXT are already used in NAS, and can be adopted in NGAP.
To avoid duplication, the following changes are introduced:
* Move text_info_t, TO_ENUM, TO_TEXT to common/utils/utils.h
* Include utils.h include to ngap_messages_types.h, fgs_nas_utils.h, and fgmm_lib.h
* RRC establishment cause: refactor to FOREACH_RRC_ESTABLISHMENT_CAUSE macro
* Cause Group: refactor to FOREACH_CAUSE_GROUP macro
* Radio Network Cause: refactor to FOREACH_CAUSE_RADIO_NETWORK macro
* Protocol Cause: refactor to FOREACH_CAUSE_PROTOCOL macro
This change is preparatory to the introduction the paging lib with unit
tests, with the goal of reducing the inter-dependency between concurrent
NGAP libs.
These conversion functions will be needed across different
NGAP libraries upon refactoring: tnl_to_bitstring, bitstring_to_tnl
Therefore, they are moved to the common lib.
PDU session related NGAP messages do not belong to NAS procedures lib.
* Create ngap_gNB_pdu_session_management.c and .h
* Move out ngap_gNB_pdusession_setup_resp, ngap_gNB_pdusession_modify_resp,
ngap_gNB_pdusession_release_resp from ngap_gNB_nas_procedures.c
* Move encode_ngap_pdusession_setup_response_transfer to ngap_common.c:
this transfer IE is common used both in PDU Session Management and
Initial Context Setup, so it's moved to the common lib
* Add ngap_gNB_pdu_session_management.c to CMakeLists.txt
This commit centralizes equality-check behavior and removes duplicated
macro implementations across protocol stacks.
Major changes:
- add `common/utils/eq_check.h` with shared `_EQ_CHECK_*`,
`EQ_CHECK_GENERIC`, and optional-IE pointer helpers
- replace E1AP/F1AP/NAS local equality macros and call sites with
the shared helpers
- remove duplicated layer-specific error/equality macro definitions from
common headers and switch includes to `eq_check.h`
- update CMake test flags to define `ENABLE_TESTS` for `e1ap_lib`,
and 5GS NAS libraries; drop `E1AP_LOG_ERRORS` - equality-check/error
printing is now consistently controlled by `ENABLE_TESTS`
Centralizes 5G-S-TMSI bit manipulation logic for consistency and
maintainability. All manual bit operations replaced with documented
helper functions following TS 23.003 bit layout specification.
- Add helper functions for 5G-S-TMSI operations:
* nr_construct_5g_s_tmsi_part1: 5G-S-TMSI construction is defined
in 3GPP TS 23.003 and relevant at both gNB and UE side
* Add helper functions to be later used in NG Paging
* Adopt in NAS UE
* nr_extract_5g_s_tmsi_part1() - extract Part1 (39 bits) from full
* nr_extract_5g_s_tmsi_part2() - extract Part2 (9 bits) from full
* nr_build_full_5g_s_tmsi() - reconstruct full from Part1+Part2
* nr_deconstruct_5g_s_tmsi() - deconstruct into components
- Refactor manual bit manipulation to use helper functions:
* asn1_msg.c: use nr_extract_5g_s_tmsi_part1() in RRCSetupRequest
* asn1_msg.c: use nr_extract_5g_s_tmsi_part2() in RRCSetupComplete
* rrc_gNB.c: use nr_build_full_5g_s_tmsi() when reconstructing from parts
* rrc_gNB.c: use nr_deconstruct_5g_s_tmsi() when extracting components
- Optimize nr_construct_5g_s_tmsi_part1() to reuse extract function
There is no such thing as NG Register message, the naming is
inaccurate, however the goal of this commit is only to clarify that
and major refactoring is not yet carried out.
Move rrc_update_ue_pcell() from static function in rrc_gNB.c to public
function in rrc_cell_management.c, making it reusable across RRC code
paths. Replace duplicate PCell addition logic in handover paths
(intra-CU and inter-CU) and RRCSetup path with calls to this shared
function.
This eliminates code duplication between handover and RRCSetup paths,
centralizes PCell update logic (including cleanup of old PCell's DU
serving cells) in a single reusable function and makes the function
available for future use in other RRC procedures
Robert Schmidt