Introduce SRS physical simulator and improvements
This MR consists of two parts:
- Introduces SRS physical simulator to test different configurations of
SRS
- Improvements in the SRS channel estimation (Addressing the comments
from old, unfinished MR !2875)
- rewrite nr_srs_channel_estimation() to loop over rx antennas and
antenna ports to be able to parallelize
- Improvements in timing_advance_offset and timing_advance_offset_nsec
computation
- Introduce SRS multi-symbol channel estimation
- The channel impulse response is estimated from the averaged
channel frequency response over multiple symbols
- The channel frequency estimates are left as they are to be able to
estimate doppler in the future
- Simplify SRS channel estimation to handle memory alignment in the
case of different SRS configurations (eg: comboffset)
To use multiple symbols when running gNB, the following parameters needs
to be edited in the function get_srs_resource()
- srs_res->resourceMapping.startPosition with a range from {0,1,..,5}
corresponds to the start symbol {13, 12, .. 8} with in a slot
- srs_res->resourceMapping.nrofSymbols indicates the number of symbols
{n1, n2, and n4}
Make sure the that start symbol + number of symbols is < 14
The timing results for SRS in develop and srs_phy_simulator are as follows:
Command used: sudo ./nr_ulsim -n1000 -s50 -S50 -R273 -W2 -y2 -z2 -E 1 -P
develop
|__ RX SRS time 124.94 us (1000 trials) (124.94 total [ms])
|__ Generate SRS sequence time 0.05 us (1000 trials) ( 0.05 total [ms])
|__ Get SRS signal time 19.41 us (1000 trials) ( 19.41 total [ms])
|__ SRS channel estimation time 89.11 us (1000 trials) ( 89.11 total [ms])
|__ SRS timing advance estimation time 13.10 us (1000 trials) ( 13.10 total [ms])
|__ SRS report TLV build time 2.80 us (1000 trials) ( 2.80 total [ms])
|__ SRS beam report build time 0.00 us ( 0 trials)
|__ SRS IQ matrix build time 2.73 us (1000 trials)
srs_phy_simulator
|__ RX SRS time 211.93 us (1000 trials) (211.93 total [ms])
|__ Generate SRS sequence time 0.04 us (1000 trials) ( 0.04 total [ms])
|__ Get SRS signal time 19.55 us (1000 trials) ( 19.55 total [ms])
|__ SRS channel estimation time 152.05 us (1000 trials) (152.05 total [ms])
|__ SRS timing advance estimation time 36.67 us (1000 trials) ( 36.67 total [ms])
|__ SRS report TLV build time 2.96 us (1000 trials) ( 2.96 total [ms])
|__ SRS beam report build time 0.00 us ( 0 trials)
|__ SRS IQ matrix build time 2.88 us (1000 trials)
Note that in srs_phy_simulator, to compute timing offset ns, an
oversampling factor of 2 is performed. Also, for peak detection, we
average the channel estimates for every port.
atoi() used previously does not capture all of unsigned long (so we
could not reproduce a high seed), and its use is discouraged as it does
not detect errors. Use strtoul() instead, which allows to also use other
bases (so we can e.g., write OAI_RNGSEED=0x1234)
Hide normal table initialization of Ziggurat generator from outside to
force the usage of randominit() for RNG initialization. In this step,
remove the randominit() seed parameter and only rely on OAI_RNGSEED for
a consistent RNG initialization, as this parameter was used differently
("0" as fixed number or to force a random seed).
Now, only use OAI_RNGSEED env variable to force the usage of a fixed
seed.
Since there is no UCI on PUSCH implementation in gNB, it is good to test
UE's implementation with matlab.
This commit allows to test with matlab in two ways:
1. generate OFDM waveform from ulsim and decode it in matlab using
uci_on_pusch_decode.m
2. generate codeword in matlab using uci_on_pusch_encode.m read it in
ulsim and compare the bits. ulsim option -o is used
Added a libary that can connect to a channel emulator and provide taps
as they are generated.
- Enable connection from vrtsim to channel emulation server
- Depends on flatbuffers definition file from raytracing-channel-emulator
- Depends on libanomsg-dev and flatbuffers-compiler (Ubuntu) or equivalent
- Added a compile time option ENABLE_TAPS_CLIENT to prevent other users
from being affected by additional dependencies
Use `rfsimu_channel_ue1`, `rfsimu_channel_ue2`, etc. if you want to
use different channel models for each client. The client connection
order determines its channel model name.
Added new command line option to channelmod: noise_power_dBFS. This options
allows the user to configure noise power in dBFS added instead of the per-channel
value.
This makes it so noise is not accumulated per channel reaching higher than expected
values.
The dBFS unit allows easy configuration. The gNB by default uses -36 dBFS setting.
To reach 3dB SNR one should set the noise_power_dBFS value to -39.
To configure using command line use --channelmod.noise_power_dBFS -50. Using this
setting the gNB and nrUE connect without issue.
Add the option `--rfsimulator.prop_delay` to specify the simulated receive-path (gNB: UL, UE: DL) propagation delay in ms.
This option can be used e.g. to simulate a simple GEO satellite channel by specifying `--rfsimulator.prop_delay 238.74` to both, the gNB and the UE.
This is part of the work developed by Fraunhofer IIS within the ESA-funded project 5G-GOA (https://connectivity.esa.int/projects/5ggoa).
- deleted: ../../../executables/rfsim.c
- removed unused command line options to set SINR and SNR
- removed unused functions to get SINR and SNR
- removed unused RFSIM struct members
Testing on Neoverse N1 (Ampere 3GHz). Tested only on a subset of phy-simulators.
- Changes:
- use SIMDE consistently
- adaptations of LDPC decoder generator for ARMv8 performance
- SIMDe modifications of Intel CRC to allow for aarch64 build.
optimizations for 128-bit to improve performance of LDPC encode/decode
on aarch64 (Neoverse 1)
- added BG2 files for 128-bit ldpc encoder (aarch64)
- testing on Xeon
- testing on x86
- minor changes to build/run on x86
- change in crc.h after returning to aarch64
- removed some warning in ldpc decoder generator for x86_64
- char
- Delete irrelevant constants
- Correctly declare variables
- Define stdbool for all architectures
- Remove definition of _MM_SHUFFLE and use SIMDE_MM_SHUFFLE
- Remove commented code
- Fix CMakeLists.txt
- Include SIMDE avx2 functions in tools_defs.h
This commit includes changes to the function
footprints for vaiours NR UE and gNB functions.
It does not updated the LTE code. For functions
shared by both LTE and 5G, we maintained the original
LTE footprint and argument structure.
Several of the simulators that use these functions
have been updated as well. The specific usage of these
functions which index into the int32_t buffers and
treat the first int16_t and the real and the second
as the complex should be modified in the near future.
Most targets don't need the symbols from the compiled RRC ASN.1
libraries, but only the headers. In particular when compiling individual
libraries (e.g., for tests), linking the full library makes the RRC
ASN.1 libraries compile and link, when they are not needed (only headers
are needed).
For libraries that can do without these headers, don't link them.
Robert Schmidt