O-DU Low Project Introduction¶
The O-DU low project focus on the baseband PHY Reference Design, which uses Xeon® series Processor with Intel Architecture. This 5GNR Reference PHY consists of a L1 binary and three kinds of interfaces which are validated on a Intel® Xeon® SkyLake / CascadeLake platforms and demonstrates the capabilities of the software running different 5GNR L1 features. It implements the relevant functions described in [3GPP TS 38.211, 212, 213, 214 and 215].
The L1 has three interfaces to communicate with other network functions as described below:
- Interface between L1 and Front Haul, it adopts the WG4 specification for the CUS plane communication.
- Interface between O-DU Low and O-DU High, it adopts the FAPI interface according to the WG8 AAL specification.
- Interface between O-DU Low and accelerator, DPDK BBDev was adopted as original contribution, it will follow the WG6 definition after the WG6 specification is finalized.
The following figure shows the ORAN O-CU, O-DU and O-RU blocks for a gNB implemetation. The O-DU Low projects implements the FAPI interface by a 5G FAPI TM module, the OFH-U and OFH-C by means of the FHI Library and the functionality of the High-PHY and a test MAC are available through github in the form of a binary blob for the current release. For the details refer to the Running L1 and Testmac section of this document
In this O-DU Low document, the details on how the build the modules supporting each interface, how to run the L1 and associated components, the architecture for each interface implementation and the release notes that describe each component release details are provided.
The intended audience for this document are software engineers and system architects who design and develop
5G systems using the O-RAN Specifications.
Table 1. Terminology
|5G NR||Fifth Generation New Radio|
|BOM||Bill of Materials|
|DPDK||Data Plane Development Kit|
|gNB||Next-generation NodeB also named as Base Station|
|HARQ||Hybrid Automatic Repeat Request|
|IQ||In-band and Quadrature|
|NIC||Network Interface Controller|
|O-DU||O-RAN Distributed Unit: a logical node hosting RLC/MAC/High-PHY layers based on a lower layer functional split.|
|O-RU||O-RAN Radio Unit: a logical node hosting Low-PHY layer and RF processing based on a lower layer functional split. This is similar to 3GPP’s “TRP” or “RRH” but more specific in including the Low-PHY layer (FFT/IFFT, PRACH extraction).|
|PDCCH||Physical Downlink Control Channel|
|PDSCH||Physical Downlink Shared Channel|
|PRACH||Physical Random Access Channel|
|PUCCH||Physical Uplink Control Channel|
|PUSCH||Physical Uplink Shared Channel|
|PTP||Precision Time Protocol|
|RAN||Radio Access Network|
|SR-IOV||Single Root Input/Output Virtualization|
|ToS||Top of the Second|
|VIM||Virtual Infrastructure Manager|
|VLAN||Virtual Local Area Network|
|xRAN||Extensible Radio Access Network|
Table 2. Reference Documents
|Document or Reference||Document No./ Location|
|3GPP* specification series||http://www.3gpp.org/DynaReport/38-series.htm|
|Wolf Pass Server Documentation||https://ark.intel.com/products/codename/80739/Wolf-Pass|
|Intel® C++ Compiler system Studio XE||https://software.intel.com/en-us/system-studio/choose-download|
|O-RAN Fronthaul Working Group Control, User and Synchronization Plane Specification (ORAN-WG4.CUS.0-v02.00)||https://www.o-ran.org/specifications|