O-RAN FAPI 5G TM Introduction

The ORAN FAPI 5G Translator Module (TM) is a standalone application that communicates with the ODU-High using the 5G FAPI protocol defined by the Small Cell Forum and communicates with the ODU Low using the Intel L2-L1 API using the Wireless Subsystem Interface Library (WLS) to handle the shared memory and buffer management required by the Interfaces. In addition the ORAN 5G FAPI TM requires the Data Plane Design Kit (DPDK) which is integrated with the WLS Library.

Table 1. Terminology

Term Description
API Application Platform Interface
BBU Baseband Unit
CORESET Control Resource Set
DOS Denial of Service Attack
DPDK Data Plane Design Kit
eNb Enode B
EPC Evolved Packet Core
EVM Error Vector magnitude
FAPI Functional Application Platform Interface
gNB Next generation eNB or g Node B
IQ In-phase and in-quadrature
ISA Intel Software Architecture i.e. AVX2, AVX256, AVX512
MAC Medium Access Control
MIB Master Information Block
nFAPI Network FAPI (Between VNF(L2/L3) and PNF(L1))
PDU Protocol Data Unit
PHY Physical Layer Processing
PMD Poll Mode Driver
PNF Physical Network Function
PSS Primary Synchronization Signal
QPSK Quadrature Phase Shift Keying
RAN Radio Access Network
RE Radio Equipment
REC Radio Equipment Control
ROE Radio Over Ethernet
RX or Rx Receive
SCF Small Cell Forum
SFN System Frame Number ∈ {0,…,1023}
SIB System Information Block
SSS Secondary Synchronization Signal
TLV Type Length Value
TX or Tx Transmit
U-Plane User Plane
URLLC Ultra Reliable Low Latency Coding
VNF Virtual Network Function
WLS Wireless Subsystem Interface
WLS_DPDK WLS that uses DPDK functions instead of accessing kernel functions

Reference Documents

Table 2. Reference Documents

Document Document No./Location
  1. FlexRAN 5G New Radio Reference Solution L1-L2 API Specification July 2019
CDI 603575 Intel Corp.
  1. 5G FAPI:PHY API Specification, Version 1.0.5, March 2020
222.10.02/ smallcellforum.org

Translator Module Top Level Design

The following diagram illustrates the different functions and components used by this module and how it interconnects to the L2 and L1 layers.

Figure 1. ORAN 5G FAPI Translator Module Top Level Architecture

Figure 1. ORAN 5G FAPI TM

Figure 1. ORAN 5G FAPI TM Top Level Diagram

The Translator Module consists of the following functions:

  • A 5G FAPI Parser facing the L2 interface.
  • An Inter API Mapper and Logic.
  • An Intel API Parser facing the L1 interface.
  • WLS dpdk based library supporting 2 instances.