.. See the License for the specific language governing permissions and
.. limitations under the License.
-.. |br| raw:: html
-
- <br />
Architecture Overview
=====================
:depth: 3
:local:
-This section provides an overview of the xRAN architecture.
+This section provides an overview of the O-RAN architecture.
.. _introduction-1:
Introduction
------------
-The front haul interface, according to the ORAN Fronthaul specification,
-performs communication between O-RAN Distributed Unit (O-DU) and O-RAN
-Radio Unit (O-RU) and consists of multiple HW and SW components.
+The front haul interface, according to the O-RAN Fronthaul
+specification, is part of the 5G NR L1 reference implementation provided
+with the FlexRAN software package. It performs communication between
+O-RAN Distributed Unit (O-DU) and O-RAN Radio Unit (O-RU) and consists
+of multiple HW and SW components.
+
+The logical representation of HW and SW components is shown in *Figure
+1*.
-The logical representation of HW and SW components is shown in Figure 1.
+The same architecture design is applicable for LTE; however, the FH
+library is not integrated with the PHY pipeline for FlexRAN LTE.
.. image:: images/Architecture-Block-Diagram.jpg
:width: 600
Figure 1. Architecture Block Diagram
-|br|
-|br|
+
+
From the hardware perspective, two networking ports are used to
communicate to the Front Haul and Back (Mid) Haul network as well as to
From the software perspective, the following components are used:
-* Linux PTP provides synchronization of system timer to GPS time:
+* Linux\* PTP provides synchronization of system timer to GPS time:
+ - ptp4l is used to synchronize oscillator on Network Interface Controller (NIC) to PTP GM.
+ - phc2sys is used to synchronize system timer to oscillator on NIC.
- - Ptp4l is used to synchronize oscillator on Network Interface
- Controller (NIC) to PTP GM.
+* The DPDK to provide the interface to the Ethernet port.
- - Phc2sys is used to synchronize system timer to oscillator on NIC.
+* O-RAN library is built on top of DPDK to perform U-plane and C-plane functionality according to the O-RAN Fronthaul specification.
-* DPDK to provide the interface to the Ethernet port.
+* 5GNR reference PHY uses the O-RAN library to access interface to O-RU. The interface between the library and PHY is defined to communicate TTI event, symbol time, C-plane information as well as IQ sample data.
-* xRAN library is built on top of DPDK to perform U-plane and C-plane
- functionality according to the ORAN Fronthaul specification.
+* 5G NR PHY communicates with the L2 application using the set of MAC/PHY APIs and the shared memory interface defined as WLS.
-* 5GNR reference PHY uses the xRAN library to access interface to O-RU.
- The interface between the library and PHY is defined to communicate
- TTI event, symbol time, C-plane information as well as IQ sample
- data.
+* L2, in turn, can use Back (Mid) Haul networking port to connect to the CU unit in the context of 3GPP specification.
-* 5G NR PHY communicates with the L2 application using the set of
- MAC/PHY APIs and the shared memory interface defined as WLS.
+In this document, we focus on details of the design and implementation
+of the O-RAN library for providing Front Haul functionality for both
+mmWave and Sub-6 scenarios as well as LTE.
-* L2, in turn, can use Back (Mid) Haul networking port to connect to
- the CU unit in the context of 3GPP specification.
-
-In this document, we focus on the details of the design and
-implementation of the xRAN library with respect to providing Front Haul
-functionality for both mmWave and Sub-6 scenarios.
-
-The xRAN M-plane is not implemented and is outside of the scope of this
+The O-RAN M-plane is not implemented and is outside of the scope of this
description. Configuration files are used to specify selected M-plane
level parameters.
-ORAN FH Threads
----------------
+5G NR L1 Application Threads
+----------------------------
+
+The specifics of the L1 application design and configuration for the
+given scenario can be found in document 603577, *FlexRAN 5G NR Reference
+Solution RefPHY* (Doxygen) (refer to *Table 2*) Only information
+relevant to front haul is presented in this section.
+
+Configuration of l1app with O-RAN interface for Front Haul is illustrated
+acting as an O-DU in *Figure 2*.
-ORAN FH Thread Performs:
+.. image:: images/5G-NR-L1app-Threads.jpg
+ :width: 600
+ :alt: Figure 2. 5G NR L1app Threads
+
+Figure 2. 5G NR L1app Threads
+
+In this configuration of L1app, the base architecture of 5G NR L1 is not
+changed. The original Front Haul FPGA interface was updated with the
+O-RAN fronthaul interface abstracted via the O-RAN library.
+
+O-RAN FH Thread Performs:
-- Symbol base “time event” to the rest of the system based on System
- Clock synchronized to GPS time via PTP.
+- Symbol base “time event” to the rest of the system based on System Clock synchronized to GPS time via PTP
-- Baseline polling mode driver performing TX and RX of Ethernet packets.
+- Baseline polling mode driver performing TX and RX of Ethernet packets
-- Most of the packet processing such as Transport header, Application
- header, Data section header and interactions with the rest of the PHY
- processing pipeline.
+- Most of the packet processing such as Transport header, Application header, Data section header, and interactions with the rest of the PHY processing pipeline.
-- Polling of other call back function that was registered.
+- Polling of BBDev for FEC on PAC N3000 acceleration card
-ORAN FH thread created the independent of usage of xRAN as an interface
-to the Radio.
+The other threads are standard for the L1app and created the independent
+usage of O-RAN as an interface to the Radio.
-Communication between L1 and xRAN layer is performed using a set of
-callback functions where L1 assigned callback and xRAN layer executes
+Communication between L1 and O-RAN layer is performed using a set of
+callback functions where L1 assigned callback and O-RAN layer executes
those functions at a particular event or time moment. Detailed
-information on callback function options and setting as well as design,
+information on callback function options and setting, as well as design,
can be found in the sections below.
+Design and installation of the l1app do not depend on the Host, VM, or
+container environment and the same for all cases.
+
Sample Application Thread Model
-------------------------------
-Configuration of a sample application for both O-DU and O-RU follows the
-model of 5G NR l1app application in the section of xRAN only. No BBU or
-FEC related threads are needed as minimal xRAN functionality is used
+Configuration of a sample application for both the O-DU and O-RU follows
+the model of 5G NR l1app application in *Figure 2*, but no BBU or FEC
+related threads are needed as minimal O-RAN FH functionality is used
only.
.. image:: images/Sample-Application-Threads.jpg
Figure 3. Sample Application Threads
-|br|
-|br|
-
In this scenario, the main thread is used only for initializing and
closing the application. No execution happens on core 0 during run time.
Functional Split
----------------
-Figure 1 corresponds to the O-RU part of the xRAN split. Implementation
-of the RU side of the xRAN protocol is not covered in this document.
+Figure 1 corresponds to the O-RU part of the O-RAN split.
+Implementation of the RU side of the O-RAN protocol is not covered in
+this document.
.. image:: images/eNB-gNB-Architecture-with-O-DU-and-RU.jpg
:width: 600
Figure 4. eNB/gNB Architecture with O-DU and RU
-|br|
-|br|
+
+
More than one RU can be supported with the same implementation of the
-xRAN library and depends on the configuration of gNB in general. In this
-document, we address details of implementation for single O-DU – O-RU
+O-RAN library and depends on the configuration of gNB in general. In this
+document, we address details of implementation for a single O-DU – O-RU
connection.
-The ORAN Fronthaul specification provides two categories of the split of
-Layer 1 functionality between O-DU and O‑RU: Category A and Category B.
+The O-RAN Fronthaul specification provides two categories of the split
+of Layer 1 functionality between O-DU and O-RU: Category A and Category
+B.
.. image:: images/Functional-Split.jpg
:width: 600
Figure 5. Functional Split
-|br|
+
Data Flow
---------
-|br|
+
Table 3 lists the data flows supported for a single RU with a single
Component Carrier.
-|br|
-|br|
+
+
Table 3. Supported Data Flow
+---------+----+-----------------+-----------------+----------------+
| Plane | ID | Name | Contents | Periodicity |
-+---------+----+-----------------+-----------------+----------------+
++=========+====+=================+=================+================+
| U-Plane | 1a | DL Frequency | DL user data | symbol |
| | | Domain IQ Data | (PDSCH), | |
| | | | control channel | |
| | | | PRACH | |
| | | | scheduling | |
+---------+----+-----------------+-----------------+----------------+
-| S-Plane | S | Timing and | IEEE 1588 PTP | |
+| S-Plane | S | Timing and | IEEE 1588 PTP | - |
| | | Synchronization | packets | |
+---------+----+-----------------+-----------------+----------------+
-|br|
-|br|
-
.. image:: images/Data-Flows.jpg
:width: 600
:alt: Figure 6. Data Flows
Figure 6. Data Flows
-|br|
-|br|
+
+
Information on specific features of C-Plane and U-plane provided in
-Section 6.0. Configuration of S-plane used on test setup for simulation
-is provided in Appendix Appendix 2.
+Sample Application Section Configuration of S-plane used on
+test setup for simulation is provided in Appendix 2.
Data flow separation is based on VLAN (applicable when layer 2 or layer
3 is used for the C/U-plane transport.)
-#. The mechanism for assigning VLAN ID to U-Plane and C-Plane is assumed
-to be via the M-Plane.
+* The mechanism for assigning VLAN ID to U-Plane and C-Plane is assumed to be via the M-Plane.
-VLAN Tag is configurable via the standard Linux IP tool (refer to
-Appendix Appendix 1).
+* VLAN Tag is configurable via the standard Linux IP tool, refer to Appendix A, Setup Configuration.
-No Quality of Service (QoS) is supported.
-
-|br|
-|br|
+* No Quality of Service (QoS) is implemented as part of O-RAN library. Standard functionality of ETH port can be used to implement QoS.
.. image:: images/C-plane-and-U-plane-Packet-Exchange.jpg
:width: 600
Figure 7. C-plane and U-plane Packet Exchange
-|br|
-|br|
+
+
Timing, Latency, and Synchronization to GPS
-------------------------------------------
-The ORAN Fronthaul specification defines the latency model of the front
-haul interface and interaction between O-DU and O-RU. This
-implementation of the xRAN library supports only the category with fixed
-timing advance and Defined Transport method. It determines O-DU transmit
-and receive windows based on pre-defined transport network characteristics, and the delay characteristics of the RUs within the
+The O-RAN Fronthaul specification defines the latency model of the front
+haul interface and interaction between O-DU and 0-RU. This
+implementation of the O-RAN library supports only the category with fixed
+timing advance and Defined Transport methods. It determines O-DU
+transmit and receive windows based on pre-defined transport network
+characteristics, and the delay characteristics of the RUs within the
timing domain.
Table 4 below provides default values used for the implementation of
-O-DU – O-RU simulation with mmWave scenario. Table 5 and Table 6 below
+O-DU – O-RU simulation with mmWave scenario. Table 5 and *Table 6* below
provide default values used for the implementation of O-DU – O-RU
simulation with numerology 0 and numerology 1 for Sub6 scenarios.
-Configuration can be adjusted via configuration files for sample |br|
-application and reference PHY. However, simulation of the different
-range of the settings was not performed, and additional implementation changes might be required as well as testing with actual O-RU. The
-parameters for the front haul network are out of scope as a direct connection between O-DU and 0-RU is used for simulation.
+Configuration can be adjusted via configuration files for sample
+application and reference PHY.
-|br|
-|br|
+However, simulation of the different range of the settings was not
+performed, and additional implementation changes might be required as
+well as testing with actual O-RU. The parameters for the front haul
+network are out of scope as a direct connection between O-DU and 0-RU
+is used for simulation.
Table 4. Front Haul Interface Latency (numerology 3 - mmWave)
+------+------------+-------------------+-------------------+----------------+------------+
-| | Model | C-Plane | U-Plane | | |
-| | Parameters | | | | |
-+------+------------+-------------------+-------------------+----------------+------------+
+| | Model | C-Plane | U-Plane |
+| | Parameters | | |
++ + +-------------------+-------------------+----------------+------------+
| | | DL | UL | DL | UL |
+------+------------+-------------------+-------------------+----------------+------------+
| O-RU | T2amin | T2a_min_cp_dl=50 | T2a_min_cp_ul=50 | T2a_min_up=25 | NA |
-+------+------------+-------------------+-------------------+----------------+------------+
++ +------------+-------------------+-------------------+----------------+------------+
| | T2amax | T2a_max_cp_dl=140 | T2a_max_cp_ul=140 | T2a_max_up=140 | NA |
-+------+------------+-------------------+-------------------+----------------+------------+
++ +------------+-------------------+-------------------+----------------+------------+
| | | Tadv_cp_dl | NA | NA | NA |
-+------+------------+-------------------+-------------------+----------------+------------+
++ +------------+-------------------+-------------------+----------------+------------+
| | Ta3min | NA | NA | NA | Ta3_min=20 |
-+------+------------+-------------------+-------------------+----------------+------------+
++ +------------+-------------------+-------------------+----------------+------------+
| | Ta3max | NA | NA | NA | Ta3_max=32 |
+------+------------+-------------------+-------------------+----------------+------------+
| O-DU | T1amin | T1a_min_cp_dl=70 | T1a_min_cp_ul=60 | T1a_min_up=35 | NA |
-+------+------------+-------------------+-------------------+----------------+------------+
++ +------------+-------------------+-------------------+----------------+------------+
| | T1amax | T1a_max_cp_dl=100 | T1a_max_cp_ul=70 | T1a_max_up=50 | NA |
-+------+------------+-------------------+-------------------+----------------+------------+
++ +------------+-------------------+-------------------+----------------+------------+
| | Ta4min | NA | NA | NA | Ta4_min=0 |
-+------+------------+-------------------+-------------------+----------------+------------+
++ +------------+-------------------+-------------------+----------------+------------+
| | Ta4max | NA | NA | NA | Ta4_max=45 |
+------+------------+-------------------+-------------------+----------------+------------+
-|br|
-|br|
-|br|
-
Table 5. Front Haul Interface Latency (numerology 0 - Sub6)
+------+----------+----------+----------+----------+----------+
-| | Model | C-Plane | U-Plane | | |
+| | Model | C-Plane | | U-Plane | |
| | Pa | | | | |
| | rameters | | | | |
-+------+----------+----------+----------+----------+----------+
++ + +----------+----------+----------+----------+
| | | DL | UL | DL | UL |
+------+----------+----------+----------+----------+----------+
| O-RU | T2amin | T | T | T2a_mi | NA |
| | | 2a_min_c | 2a_min_c | n_up=200 | |
| | | p_dl=400 | p_ul=400 | | |
-+------+----------+----------+----------+----------+----------+
++ +----------+----------+----------+----------+----------+
| | T2amax | T2 | T2 | T2a_max | NA |
| | | a_max_cp | a_max_cp | _up=1120 | |
| | | _dl=1120 | _ul=1120 | | |
-+------+----------+----------+----------+----------+----------+
++ +----------+----------+----------+----------+----------+
| | | Ta | NA | NA | NA |
| | | dv_cp_dl | | | |
-+------+----------+----------+----------+----------+----------+
++ +----------+----------+----------+----------+----------+
| | Ta3min | NA | NA | NA | Ta3 |
| | | | | | _min=160 |
-+------+----------+----------+----------+----------+----------+
++ +----------+----------+----------+----------+----------+
| | Ta3max | NA | NA | NA | Ta3 |
| | | | | | _max=256 |
+------+----------+----------+----------+----------+----------+
| O-DU | T1amin | T | T | T1a_mi | NA |
| | | 1a_min_c | 1a_min_c | n_up=280 | |
| | | p_dl=560 | p_ul=480 | | |
-+------+----------+----------+----------+----------+----------+
++ +----------+----------+----------+----------+----------+
| | T1amax | T | T | T1a_ma | NA |
| | | 1a_max_c | 1a_max_c | x_up=400 | |
| | | p_dl=800 | p_ul=560 | | |
-+------+----------+----------+----------+----------+----------+
++ +----------+----------+----------+----------+----------+
| | Ta4min | NA | NA | NA | T |
| | | | | | a4_min=0 |
-+------+----------+----------+----------+----------+----------+
++ +----------+----------+----------+----------+----------+
| | Ta4max | NA | NA | NA | Ta4 |
| | | | | | _max=360 |
+------+----------+----------+----------+----------+----------+
-|br|
-|br|
-|br|
+
+
+
Table 6. Front Haul Interface Latency (numerology 1 - Sub6)
+------+------------+-------------------+-------------------+----------------+------------+
| | Model | C-Plane | U-Plane | | |
| | Parameters | | | | |
-+------+------------+-------------------+-------------------+----------------+------------+
++ + +-------------------+-------------------+----------------+------------+
| | | DL | UL | DL | UL |
+------+------------+-------------------+-------------------+----------------+------------+
| O-RU | T2amin | T2a_min_cp_dl=285 | T2a_min_cp_ul=285 | T2a_min_up=71 | NA |
-+------+------------+-------------------+-------------------+----------------+------------+
++ +------------+-------------------+-------------------+----------------+------------+
| | T2amax | T2a_max_cp_dl=429 | T2a_max_cp_ul=429 | T2a_max_up=428 | NA |
-+------+------------+-------------------+-------------------+----------------+------------+
++ +------------+-------------------+-------------------+----------------+------------+
| | | Tadv_cp_dl | NA | NA | NA |
-+------+------------+-------------------+-------------------+----------------+------------+
++ +------------+-------------------+-------------------+----------------+------------+
| | Ta3min | NA | NA | NA | Ta3_min=20 |
-+------+------------+-------------------+-------------------+----------------+------------+
++ +------------+-------------------+-------------------+----------------+------------+
| | Ta3max | NA | NA | NA | Ta3_max=32 |
+------+------------+-------------------+-------------------+----------------+------------+
| O-DU | T1amin | T1a_min_cp_dl=285 | T1a_min_cp_ul=285 | T1a_min_up=96 | NA |
-+------+------------+-------------------+-------------------+----------------+------------+
++ +------------+-------------------+-------------------+----------------+------------+
| | T1amax | T1a_max_cp_dl=429 | T1a_max_cp_ul=300 | T1a_max_up=196 | NA |
-+------+------------+-------------------+-------------------+----------------+------------+
++ +------------+-------------------+-------------------+----------------+------------+
| | Ta4min | NA | NA | NA | Ta4_min=0 |
-+------+------------+-------------------+-------------------+----------------+------------+
++ +------------+-------------------+-------------------+----------------+------------+
| | Ta4max | NA | NA | NA | Ta4_max=75 |
+------+------------+-------------------+-------------------+----------------+------------+
-|br|
-|br|
-|br|
+
+
+
IEEE 1588 protocol and PTP for Linux\* implementations are used to
synchronize local time to GPS time. Details of the configuration used
-are provided in Appendix Appendix 2. Local time is used to get Top of
-the Second (ToS) as a 1pps event for SW implementation. Timing event is
-obtained by performing polling of local time using clock_gettime(CLOCK_REALTIME,..)
+are provided in Appendix B, PTP Configuration. Local time is used to get
+Top of the Second (ToS) as a 1 PPS event for SW implementation. Timing
+event is obtained by performing polling of local time using
+clock_gettime(CLOCK_REALTIME,..)
-All-time intervals are specified with respect to GPS time which
+All-time intervals are specified concerning the GPS time, which
corresponds to OTA time.
-|br|
-|br|
-|br|
-
Virtualization and Container-Based Usage
----------------------------------------
-xRAN implementation is deployment agnostic and does not require special
-changes to be used in virtualized or |br|
-container-based deployment options.
+O-RAN implementation is deployment agnostic and does not require special
+changes to be used in virtualized or container-based deployment options.
The only requirement is to provide one SRIOV base virtual port for
C-plane and one port for U-plane traffic per O-DU instance. This can be
achieved with the default Virtual Infrastructure Manager (VIM) as well
+To configure the networking ports, refer to the FlexRAN and Mobile Edge
+Compute (MEC) Platform Setup Guide (*Table 2*) and readme.md in O-RAN
+library or Appendix A.
Code Review / o-du / phy.git / blobdiff