3. SW Turbo Poll Mode Driver

The SW Turbo PMD (baseband_turbo_sw) provides a software only poll mode bbdev driver that can optionally utilize Intel optimized libraries for LTE and 5GNR Layer 1 workloads acceleration.

Note that the driver can also be built without any dependency with reduced functionality for maintenance purpose.

To enable linking to the SDK libraries see detailed installation section below.

This PMD supports the functions: FEC, Rate Matching and CRC functions detailed in the Features section.

3.1. Features

SW Turbo PMD can support for the following capabilities when the SDK libraries are used:

For the LTE encode operation:

  • RTE_BBDEV_TURBO_CRC_24A_ATTACH
  • RTE_BBDEV_TURBO_CRC_24B_ATTACH
  • RTE_BBDEV_TURBO_RATE_MATCH
  • RTE_BBDEV_TURBO_RV_INDEX_BYPASS

For the LTE decode operation:

  • RTE_BBDEV_TURBO_SUBBLOCK_DEINTERLEAVE
  • RTE_BBDEV_TURBO_CRC_TYPE_24B
  • RTE_BBDEV_TURBO_POS_LLR_1_BIT_IN
  • RTE_BBDEV_TURBO_NEG_LLR_1_BIT_IN
  • RTE_BBDEV_TURBO_DEC_TB_CRC_24B_KEEP
  • RTE_BBDEV_TURBO_EARLY_TERMINATION

For the 5G NR LDPC encode operation:

  • RTE_BBDEV_LDPC_RATE_MATCH
  • RTE_BBDEV_LDPC_CRC_24A_ATTACH
  • RTE_BBDEV_LDPC_CRC_24B_ATTACH

For the 5G NR LDPC decode operation:

  • RTE_BBDEV_LDPC_CRC_TYPE_24B_CHECK
  • RTE_BBDEV_LDPC_CRC_TYPE_24A_CHECK
  • RTE_BBDEV_LDPC_CRC_TYPE_24B_DROP
  • RTE_BBDEV_LDPC_HQ_COMBINE_IN_ENABLE
  • RTE_BBDEV_LDPC_HQ_COMBINE_OUT_ENABLE
  • RTE_BBDEV_LDPC_ITERATION_STOP_ENABLE

3.2. Limitations

  • In-place operations for encode and decode are not supported

3.3. Installation

3.3.1. FlexRAN SDK Download

As an option it is possible to link this driver with FleXRAN SDK libraries which can enable real time signal processing using AVX instructions.

These libraries are available through this link.

After download is complete, the user needs to unpack and compile on their system before building DPDK.

The following table maps DPDK versions with past FlexRAN SDK releases:

Table 3.1 DPDK and FlexRAN FEC SDK releases compliance
DPDK version FlexRAN FEC SDK release
19.08 to 22.07 19.04
22.11+ 22.11

3.3.2. FlexRAN SDK Installation

Note that the installation of these libraries is optional.

The following are pre-requisites for building FlexRAN SDK Libraries:
  1. An AVX2 or AVX512 supporting machine
  2. CentOS Linux release 7.2.1511 (Core) operating system is advised
  3. Intel ICC 18.0.1 20171018 compiler or more recent and related libraries ICC is available with a free community license.

The following instructions should be followed in this exact order:

  1. Set the environment variables:

    source <path-to-icc-compiler-install-folder>/linux/bin/compilervars.sh intel64 -platform linux

  2. Run the SDK extractor script and accept the license:

    cd <path-to-workspace>
./FlexRAN-FEC-SDK-19-04.sh

  3. Generate makefiles based on system configuration:

    cd <path-to-workspace>/FlexRAN-FEC-SDK-19-04/sdk/
./create-makefiles-linux.sh

  4. A build folder is generated in this form build-<ISA>-<CC>, enter that folder and install:

    cd build-avx512-icc/
make && make install

3.4. Initialization

In order to enable this virtual bbdev PMD, the user may:

  • Build the FLEXRAN SDK libraries (explained in Installation section).
  • Export the environmental variables FLEXRAN_SDK to the path where the FlexRAN SDK libraries were installed. And DIR_WIRELESS_SDK to the path where the libraries were extracted.
  • Point pkgconfig towards these libraries so that they can be automatically found by meson. If not, DPDK will still compile but the related functionality would be stubbed out.

Example:

export FLEXRAN_SDK=<path-to-workspace>/FlexRAN-FEC-SDK-19-04/sdk/build-avx2-icc/install
export DIR_WIRELESS_SDK=<path-to-workspace>/FlexRAN-FEC-SDK-19-04/sdk/build-avx2-icc/
export PKG_CONFIG_PATH=$DIR_WIRELESS_SDK/pkgcfg:$PKG_CONFIG_PATH
cd build
meson configure
  • For AVX512 machines with SDK libraries installed then both 4G and 5G can be enabled for full real time FEC capability. For AVX2 machines it is possible to only enable the 4G libraries and the PMD capabilities will be limited to 4G FEC. If no library is present then the PMD will still build but its capabilities will be limited accordingly.

To use the PMD in an application, user must:

  • Call rte_vdev_init("baseband_turbo_sw") within the application.
  • Use --vdev="baseband_turbo_sw" in the EAL options, which will call rte_vdev_init() internally.

The following parameters (all optional) can be provided in the previous two calls:

  • socket_id: Specify the socket where the memory for the device is going to be allocated (by default, socket_id will be the socket where the core that is creating the PMD is running on).
  • max_nb_queues: Specify the maximum number of queues in the device (default is RTE_MAX_LCORE).

3.4.1. Example:

./test-bbdev.py -e="--vdev=baseband_turbo_sw,socket_id=0,max_nb_queues=8" \
-c validation -v ./turbo_*_default.data