15 KiB
LDPC coding implementation
The LDPC encoder and decoder are implemented in a shared library, dynamically loaded at run-time using the oai shared library loader. Two types of library are available with two different interfaces. There are libraries implementing the encoder and decoder of code segments and libraries implementing the encoder and decoder of slots.
LDPC slot coding
The interface of the library is defined in nrLDPC_coding_interface.h.
The code loading the LDPC library is in nrLDPC_coding_interface_load.c, in function load_nrLDPC_coding_interface, which must be called at init time.
Selecting the LDPC library at run time
By default the function int load_nrLDPC_coding_interface(void) looks for libldpc.so.
This default behavior can be changed using the oai loader configuration options in the configuration file or from the command line as shown below:
Examples of ldpc shared lib selection when running nr softmodem's:
loading default libldpc.so:
./nr-softmodem -O libconfig:gnb.band78.tm1.106PRB.usrpx300.conf:dbgl5
.......................
[CONFIG] loader.ldpc.shlibversion set to default value ""
[LIBCONFIG] loader.ldpc: 2/2 parameters successfully set, (2 to default value)
shlib_path libldpc.so
[LOADER] library libldpc.so successfully loaded
........................
libldpc.so has its decoder implemented in nrLDPC_coding_segment_decoder.c.
Its encoder is implemented in nrLDPC_coding_segment_encoder.c.
Note: The segment coding library libldpc.so is an adaptation layer between the slot coding interface and a segment coding library.
The segment coding library is libldpc_optim8segmulti.so by default but it can be chosen with option --nrLDPC_coding_segment.segment_shlibversion followed by the library version - like with --loader.ldpc.shlibversion in the slot coding case -
loading libldpc_t2.so instead of libldpc.so:
make ldpc_t2
This command creates the libldpc_t2.so shared library.
Building C object CMakeFiles/ldpc_t2.dir/openair1/PHY/CODING/nrLDPC_coding/nrLDPC_coding_t2/nrLDPC_coding_t2.c.o
Linking C shared module libldpc_t2.so
At runtime, to successfully use the T2 board, you need to install vendor specific drivers and tools.
Please refer to the dedicated documentation at LDPC_T2_OFFLOAD_SETUP.md.
./nr-softmodem -O libconfig:gnb.band78.sa.fr1.106PRB.usrpb210.conf:dbgl5 --rfsim --rfsimulator.serveraddr server --log_config.gtpu_log_level info --loader.ldpc.shlibversion _t2 --nrLDPC_coding_t2.dpdk_dev 01:00.0 --nrLDPC_coding_t2.dpdk_core_list 0-1
.......................
[CONFIG] loader.ldpc.shlibversion set to default value ""
[LIBCONFIG] loader.ldpc: 2/2 parameters successfully set, (1 to default value)
[CONFIG] shlibversion set to _t2 from command line
[CONFIG] loader.ldpc 1 options set from command line
shlib_path libldpc_t2.so
[LOADER] library libldpc_t2.so successfully loaded
........................
libldpc_t2.so has its decoder and its encoder implemented in nrLDPC_coding_t2.c.
loading libldpc_xdma.so instead of libldpc.so:
make ldpc_xdma or ninja ldpc_xdma
This command creates the libldpc_xdma.so shared library.
ninja ldpc_xdma
[2/2] Linking C shared module libldpc_xdma.so
At runtime, to successfully use the xdma, you need to install vendor specific drivers and tools.
Please refer to the dedicated documentation at LDPC_XDMA_OFFLOAD_SETUP.md.
./nr-softmodem -O libconfig:gnb.band78.sa.fr1.106PRB.usrpb210.conf:dbgl5 --rfsim --rfsimulator.serveraddr server --log_config.gtpu_log_level info --loader.ldpc.shlibversion _xdma --nrLDPC_coding_xdma.num_threads_prepare 2
.......................
[CONFIG] loader.ldpc.shlibversion set to default value ""
[LIBCONFIG] loader.ldpc: 2/2 parameters successfully set, (1 to default value)
[CONFIG] shlibversion set to _xdma from command line
[CONFIG] loader.ldpc 1 options set from command line
shlib_path libldpc_xdma.so
[LOADER] library libldpc_xdma.so successfully loaded
........................
libldpc_xdma.so has its decoder implemented in nrLDPC_coding_xdma.c.
Its encoder is implemented in nrLDPC_coding_segment_encoder.c.
Note: libldpc_xdma.so relies on a segment coding library for encoding.
The segment coding library is libldpc.so by default but it can be chosen with option --nrLDPC_coding_xdma.encoder_shlibversion followed by the library version - like with --loder.ldpc.shlibversion in the segment coding case above -
Examples of ldpc shared lib selection when running ldpctest:
Slot coding libraries cannot be used yet within ldpctest.
But they can be used within nr_ulsim, nr_dlsim, nr_ulschsim and nr_dlschsim.
In these PHY simulators, using the slot coding libraries is enabled in the exact same way as in nr-softmodem.
LDPC libraries
Libraries implementing the slotwise LDPC coding must be named libldpc<_version>.so. They must implement four functions: nrLDPC_coding_init, nrLDPC_coding_shutdown, nrLDPC_coding_decoder and nrLDPC_coding_encoder. The prototypes for these functions is defined in nrLDPC_coding_interface.h.
libldpc.so is completed.
libldpc_t2.so is completed.
libldpc_xdma.so is completed.
LDPC segment coding
The interface of the library is defined in nrLDPC_defs.h.
The code loading the LDPC library is in nrLDPC_load.c, in function load_nrLDPClib, which must be called at init time.
Note: LDPC segment coding libraries are not loaded directly by OAI but by the intermediate library libldpc.so which is implementing the LDPC slot coding interface using a LDPC segment coding library.
Selecting the LDPC library at run time
By default the function int load_nrLDPClib(void) looks for libldpc_optim8segmulti.so, this default behavior can be changed using the oai loader configuration options in the configuration file or from the command line as shown below:
Examples of ldpc shared lib selection when running nr softmodem's:
loading libldpc_optim8seg.so instead of libldpc_optim8segmulti.so:
./nr-softmodem -O libconfig:gnb.band78.tm1.106PRB.usrpx300.conf:dbgl5 --nrLDPC_coding_segment.segment_shlibversion _optim8seg
.......................
[CONFIG] nrLDPC_coding_segment.segment_shlibversion set to default value "_optim8segmulti"
[LIBCONFIG] nrLDPC_coding_segment: 1/1 parameters successfully set, (0 to default value)
[CONFIG] segment_shlibversion set to _optim8seg from command line
[CONFIG] nrLDPC_coding_segment 1 options set from command line
[LOADER] library libldpc_optim8seg.so successfully loaded
........................
loading libldpc_cl.so instead of libldpc_optim8segmulti.so:
make ldpc_cl
This command creates the libldpc_cl.so shared library. To perform this build successfully, only the OpenCL header (/usr/include/CL/opencl.h) and library (/usr/lib/x86_64-linux-gnu/libOpenCL.so)are required, they implement OpenCL API support which is not hardware dependent.
Scanning dependencies of target nrLDPC_decoder_kernels_CL
Built target nrLDPC_decoder_kernels_CL
Scanning dependencies of target ldpc_cl
Building C object CMakeFiles/ldpc_cl.dir/usr/local/oai/oai-develop/openairinterface5g/openair1/PHY/CODING/nrLDPC_decoder/nrLDPC_decoder_CL.c.o
In file included from /usr/include/CL/cl.h:32,
from /usr/include/CL/opencl.h:38,
from /usr/local/oai/oai-develop/openairinterface5g/openair1/PHY/CODING/nrLDPC_decoder/nrLDPC_decoder_CL.c:49:
/usr/include/CL/cl_version.h:34:9: note: #pragma message: cl_version.h: CL_TARGET_OPENCL_VERSION is not defined. Defaulting to 220 (OpenCL 2.2)
#pragma message("cl_version.h: CL_TARGET_OPENCL_VERSION is not defined. Defaulting to 220 (OpenCL 2.2)")
^~~~~~~
Building C object CMakeFiles/ldpc_cl.dir/usr/local/oai/oai-develop/openairinterface5g/openair1/PHY/CODING/nrLDPC_encoder/ldpc_encoder_optim8segmulti.c.o
Linking C shared module libldpc_cl.so
Built target ldpc_cl
At runtime, to successfully use hardware acceleration via OpenCL, you need to install vendor specific packages which deliver the required drivers and tools to make use of their GPU (Nvidia, Intel...) , fpga (Xilinx, Intel) or CPU (Intel, AMD, ARM...) through OpenCL.
./nr-softmodem -O libconfig:gnb.band78.sa.fr1.106PRB.usrpb210.conf:dbgl5 --rfsim --rfsimulator.serveraddr server --log_config.gtpu_log_level info --nrLDPC_coding_segment.segment_shlibversion _cl
------------------------------------------------
[LOADER] library libldpc_cl.so successfully loaded
[HW] Platform 0, OpenCL profile FULL_PROFILE
[HW] Platform 0, OpenCL version OpenCL 2.1 LINUX
[HW] Device 0 is available
[HW] Device 0, type 2 = 0x00000002: cpu
[HW] Device 0, number of Compute Units: 8
[HW] Device 0, max Work Items dimension: 3
[HW] Device 0, max Work Items size for dimension: 0 8192
[HW] Device 0, max Work Items size for dimension: 1 8192
[HW] Device 0, max Work Items size for dimension: 2 8192
[New Thread 0x7fffcc258700 (LWP 3945123)]
[New Thread 0x7fffc3e57700 (LWP 3945124)]
[New Thread 0x7fffcbe57700 (LWP 3945125)]
[New Thread 0x7fffcba56700 (LWP 3945126)]
[New Thread 0x7fffcb254700 (LWP 3945128)]
[New Thread 0x7fffcb655700 (LWP 3945127)]
[New Thread 0x7fffcae53700 (LWP 3945129)]
[HW] Platform 1, OpenCL profile FULL_PROFILE
[HW] Platform 1, OpenCL version OpenCL 2.0 beignet 1.3
[New Thread 0x7fffc965a700 (LWP 3945130)]
[Thread 0x7fffc965a700 (LWP 3945130) exited]
[HW] Device 0 is available
[HW] Device 0, type 4 = 0x00000004: gpu
[HW] Device 0, number of Compute Units: 20
[HW] Device 0, max Work Items dimension: 3
[HW] Device 0, max Work Items size for dimension: 0 512
[HW] Device 0, max Work Items size for dimension: 1 512
[HW] Device 0, max Work Items size for dimension: 2 512
-----------------------------------------------------------------
./nr-uesoftmodem -r 106 --numerology 1 --band 78 -C 3619200000 --rfsim -O libconfig:/usr/local/oai/conf/nrue_sim.conf:dbgl5 --nrLDPC_coding_segment.segment_shlibversion _cl --log_config.hw_log_level info
............................................................
[CONFIG] segment_shlibversion set to _cl from command line
[CONFIG] nrLDPC_coding_segment 1 options set from command line
[LOADER] library libldpc_cl.so successfully loaded
[HW] Platform 0, OpenCL profile FULL_PROFILE
[HW] Platform 0, OpenCL version OpenCL 2.1 LINUX
[HW] Device 0 is available
[HW] Device 0, type 2 = 0x00000002: cpu
[HW] Device 0, number of Compute Units: 8
[HW] Device 0, max Work Items dimension: 3
[HW] Device 0, max Work Items size for dimension: 0 8192
[HW] Device 0, max Work Items size for dimension: 1 8192
[HW] Device 0, max Work Items size for dimension: 2 8192
[New Thread 0x7fffecccc700 (LWP 3945413)]
[New Thread 0x7fffec8cb700 (LWP 3945415)]
[New Thread 0x7fffec4ca700 (LWP 3945414)]
[New Thread 0x7fffdf7fd700 (LWP 3945417)]
[New Thread 0x7fffdfbfe700 (LWP 3945418)]
[New Thread 0x7fffdffff700 (LWP 3945416)]
[New Thread 0x7fffd73fc700 (LWP 3945419)]
[HW] Platform 1, OpenCL profile FULL_PROFILE
[HW] Platform 1, OpenCL version OpenCL 2.0 beignet 1.3
[New Thread 0x7fffde105700 (LWP 3945420)]
[Thread 0x7fffde105700 (LWP 3945420) exited]
[HW] Device 0 is available
[HW] Device 0, type 4 = 0x00000004: gpu
[HW] Device 0, number of Compute Units: 20
[HW] Device 0, max Work Items dimension: 3
[HW] Device 0, max Work Items size for dimension: 0 512
[HW] Device 0, max Work Items size for dimension: 1 512
[HW] Device 0, max Work Items size for dimension: 2 512
------------------------------------------------------------
A mechanism to select ldpc implementation is also available in the ldpctest phy simulator via the -v option, which can be used to specify the version of the ldpc shared library to be used.
Examples of ldpc shared lib selection when running ldpctest:
Loading libldpc_cuda.so, the cuda implementation of the ldpc decoder:
$ ./ldpctest -v _cuda
ldpctest -v _cuda
Initializing random number generator, seed 0
block length 8448:
n_trials 1:
SNR0 -2.000000:
[CONFIG] get parameters from cmdline , debug flags: 0x00400000
[CONFIG] log_config: 2/3 parameters successfully set
[CONFIG] log_config: 53/53 parameters successfully set
[CONFIG] log_config: 53/53 parameters successfully set
[CONFIG] log_config: 16/16 parameters successfully set
[CONFIG] log_config: 16/16 parameters successfully set
log init done
[CONFIG] loader: 2/2 parameters successfully set
[CONFIG] loader.ldpc: 1/2 parameters successfully set
[LOADER] library libldpc_cuda.so successfully loaded
...................................
Loading libldpc_cl.so, the opencl implementation of the ldpc decoder:
make ldpc_cl
$ ./ldpctest -v _cl
Initializing random number generator, seed 0
block length 8448:
n_trials 1:
SNR0 -2.000000:
[CONFIG] get parameters from cmdline , debug flags: 0x00400000
[CONFIG] log_config: 2/3 parameters successfully set
[CONFIG] log_config: 53/53 parameters successfully set
[CONFIG] log_config: 53/53 parameters successfully set
[CONFIG] log_config: 16/16 parameters successfully set
[CONFIG] log_config: 16/16 parameters successfully set
log init done
[CONFIG] loader: 2/2 parameters successfully set
[CONFIG] loader.ldpc: 1/2 parameters successfully set
[LOADER] library libldpc_cl.so successfully loaded
[HW] Platform 0, OpenCL profile FULL_PROFILE
[HW] Platform 0, OpenCL version OpenCL 2.1 LINUX
[HW] Device 0 is available
[HW] Device 0, type 2 = 0x00000002: cpu
[HW] Device 0, number of Compute Units: 8
[HW] Device 0, max Work Items dimension: 3
[HW] Device 0, max Work Items size for dimension: 0 8192
[HW] Device 0, max Work Items size for dimension: 1 8192
[HW] Device 0, max Work Items size for dimension: 2 8192
[HW] Platform 1, OpenCL profile FULL_PROFILE
[HW] Platform 1, OpenCL version OpenCL 2.0 beignet 1.3
[HW] Device 0 is available
[HW] Device 0, type 4 = 0x00000004: gpu
[HW] Device 0, number of Compute Units: 20
[HW] Device 0, max Work Items dimension: 3
[HW] Device 0, max Work Items size for dimension: 0 512
[HW] Device 0, max Work Items size for dimension: 1 512
[HW] Device 0, max Work Items size for dimension: 2 512
................................
LDPC libraries
Libraries implementing the LDPC algorithms must be named libldpc<_version>.so, they must implement three functions: nrLDPC_initcall nrLDPC_decod and nrLDPC_encod. The prototypes for these functions is defined in nrLDPC_defs.h.
libldpc_cuda.sohas been tested with the ldpctest executable, usage from the softmodem's has to be tested.
libldpc_cl.sois under development.