White Papers

© 2019 Dell Inc. or its subsidiaries.
18 | Whitepaper – Exploring Computing Platforms for Radio Access
Networks
 FEC Encoding
o Code Block CRC Generation, Turbo Encoding (4G), LDPC Encoding (5G) and
Rate Matching (Sub-block interleaving, Bit Selection/Collection).
 FEC Decoding
o HARQ Combining, Rate De-Matching (Sub-block de-interleaving, Turbo Decoder
(4G), LDPC decoder (5G) and Code Block CRC check.
Figure 20: 4G & 5G FEC Acceleration - Encoding Example.
5 FlexRAN test setup
Intel’s FlexRAN is a software reference solution that implements Layer 1 of the BBU function of
an LTE network (and includes a stack for 5G gNB as well). At Dell, an end-to-end test platform
was created using FlexRAN as the basis for the Layer 1 software of a radio equipment controller
baseband unit. The system running FlexRAN was a PowerEdge R740 equipped with a
predecessor version of the N3000 network card, an Intel X520 Ethernet network adapter, two
Intel® Xeon® Gold 6148 CPUs at 2.4GHz (microcode version 0200004D), and 256MB of RAM.
The server was running CentOS (7.5.1804) with a real time patch to the kernel (3.10.0-rt56),
and FlexRAN version 18.12, which required DPDK version 18.08. For the FPGA offload,
patches released in versions 19.03 were introduced along with DPDK patches for BBDev.
5.1 Components and System diagram
Figure 21 depicts the setup staged to test and characterize C-RAN software. Included in the
figure is a software pipeline for layer 1, showing the modules that were identified as beneficial
for an FPGA offload. Tests were run before and after the offload was introduced. The Turbo
Encoder and Decoder are computationally intensive tasks because of the bit-level interleaving.
To
Transmitter
FEC
MAC
From
Upper
Layers
TrBlk
&
CRC
Code
Block
Seg
Code
Block
Con
C
R
C
E
N
C
R
M
Encoder
SW
HW
Modem
Scrambling
&
Modulation
Layer
Mapping &
Precoding
Resource
Element
Mapping