X-Git-Url: https://gerrit.o-ran-sc.org/r/gitweb?p=o-du%2Fphy.git;a=blobdiff_plain;f=docs%2FxRAN-Library-Design_fh.rst;fp=docs%2FxRAN-Library-Design_fh.rst;h=07e2694c6b676242e1e1ab569dc98f6d62943f4e;hp=0000000000000000000000000000000000000000;hb=9d66fca5c45c8b3e0d6eab6d51a90c8e9d2614dc;hpb=2fbf70096f64af622da983e88c5a64e90ad9bdbd

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+..    Copyright (c) 2019 Intel
+..
+..  Licensed under the Apache License, Version 2.0 (the "License");
+..  you may not use this file except in compliance with the License.
+..  You may obtain a copy of the License at
+..
+..      http://www.apache.org/licenses/LICENSE-2.0
+..
+..  Unless required by applicable law or agreed to in writing, software
+..  distributed under the License is distributed on an "AS IS" BASIS,
+..  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+..  See the License for the specific language governing permissions and
+..  limitations under the License.
+
+.. |br| raw:: html
+
+   <br />
+
+xRAN Library Design
+===================
+
+.. contents::
+    :depth: 3
+    :local:
+
+The xRAN Library consists of multiple modules where different
+functionality is encapsulated. The complete list of all \*.c and \*.h
+files as well as Makefile for xRAN (aka FHI Lib Bronze Release) release is:
+
+├──fhi_lib
+
+│   ├── lib
+
+│   │   ├── api
+
+│   │   │   ├── xran_compression.h
+
+│   │   │   ├── xran_compression.hpp
+
+│   │   │   ├── xran_cp_api.h
+
+│   │   │   ├── xran_fh_o_du.h
+
+│   │   │   ├── xran_mlog_lnx.h
+
+│   │   │   ├── xran_pkt_cp.h
+
+│   │   │   ├── xran_pkt.h
+
+│   │   │   ├── xran_pkt_up.h
+
+│   │   │   ├── xran_sync_api.h
+
+│   │   │   ├── xran_timer.h
+
+│   │   │   ├── xran_transport.h
+
+│   │   │   └── xran_up_api.h
+
+│   │   ├── ethernet
+
+│   │   │   ├── ethdi.c
+
+│   │   │   ├── ethdi.h
+
+│   │   │   ├── ethernet.c
+
+│   │   │   └── ethernet.h
+
+│   │   ├── Makefile
+
+│   │   └── src
+
+│   │   │   ├── xran_app_frag.c
+
+│   │   │   ├── xran_app_frag.h
+
+│   │   │   ├── xran_common.c
+
+│   │   │   ├── xran_common.h
+
+│   │   │   ├── xran_compression.cpp
+
+│   │   │   ├── xran_cp_api.c
+
+│   │   │   ├── xran_frame_struct.c
+
+│   │   │   ├── xran_frame_struct.h
+
+│   │   │   ├── xran_lib_mlog_tasks_id.h
+
+│   │   │   ├── xran_main.c
+
+│   │   │   ├── xran_printf.h
+
+│   │   │   ├── xran_sync_api.c
+
+│   │   │   ├── xran_timer.c
+
+│   │   │   ├── xran_transport.c
+
+│   │   │   ├── xran_ul_tables.c
+
+│   │   │   └── xran_up_api.c
+
+│   ├── readme.txt
+
+│   ├── Licenses.txt
+
+│   ├── build.sh
+
+│   └── test
+
+│   │   ├── common
+
+│   │   │   ├── common.cpp
+
+│   │   │   ├── common.hpp
+
+│   │   │   ├── common_typedef_xran.h
+
+│   │   ├── xranlib_unit_test_main.cc
+
+│   │   └── xran_lib_wrap.hpp
+
+│   │   ├── master.py
+
+│   │   ├── readme.txt
+
+│   │   └── test_xran
+
+│   │   │   ├── chain_tests.cc
+
+│   │   │   ├── compander_functional.cc
+
+│   │   │   ├── conf.json
+
+│   │   │   ├── c_plane_tests.cc
+
+│   │   │   ├── init_sys_functional.cc
+
+│   │   │   ├── Makefile
+
+│   │   │   ├── prach_functional.cc
+
+│   │   │   ├── prach_performance.cc
+
+│   │   │   ├── unittests.cc
+
+│   │   │   ├── u_plane_functional.cc
+
+General Introduction
+--------------------
+
+The xRAN Library functionality is broken down into two main sections:
+
+-  XRAN specific packet handling (src)
+
+-  Ethernet and supporting functionality (Ethernet)
+
+External functions and structures are available via set of header files
+in the API folder.
+
+This library depends on DPDK primitives to perform Ethernet networking
+in userspace, including initialization and control of Ethernet ports.
+Ethernet ports are expected to be SRIOV virtual functions (VF) but also
+can be physical functions (PF) as well
+
+This library is expected to be included in the project via
+xran_fh_o_du.h, statically compiled and linked with the L1 application
+as well as DPDK libraries. The xRAN packet processing-specific
+functionality is encapsulated into this library and not exposed to the
+rest of the 5G NR pipeline. An abstract interface similar to the mmWave
+front haul interface is defined in xran_fh_o_du.h to be available for
+usage.
+
+This way, xRAN specific changes are decoupled from the 5G NR L1
+pipeline. As a result, the design and implementation of the 5G L1
+pipeline code and xRAN library can be done in parallel, provided the
+defined interface is not modified.
+
+Ethernet consists of two modules:
+
+-  Ethernet implements xRAN specific HW Ethernet initialization, close,
+   send and receive
+
+-  ethdi provides Ethernet level software primitives to handle xRAN
+   packet exchange
+
+The xRAN layer implements the next set of functionalities:
+
+-  Common code specific for both C-plane and U-plane as well as TX and
+   RX
+
+-  Implementation of C-plane API available within the library and
+   externally
+
+-  The primary function where general library initialization and
+   configuration performed
+
+-  Module to provide the status of PTP synchronization
+
+-  Timing module where system time is polled
+
+-  eCPRI specific transport layer functions
+
+-  APIs to handle U-plane packets
+
+-  A set of utility modules for debugging (printf) and data tables are
+   included as well.
+
+.. image:: images/Illustration-of-xRAN-Sublayers.jpg
+  :width: 600
+  :alt: Figure 24. Illustration of xRAN Sublayers
+
+Figure 24. Illustration of xRAN Sublayers
+
+A detailed description of functions and input/output arguments, as well
+as key data structures, can be found in the Doxygen file for the FlexRAN
+5G NR release. In this document supplemental information is provided
+with respect to the overall design and implementation assumptions.
+
+Initialization and Close
+------------------------
+
+An example of the initialization sequence can be found in the sample
+application code. It consists of the following steps:
+
+1.Setup structure struct xran_fh_init according to configuration.
+
+2.Call xran_init() to instantiate the xRAN lib memory model and
+threads. The function returns a pointer to xRAN handle which is used
+for consecutive configuration functions.
+
+3.Initialize memory buffers used for L1 and xRAN exchange of
+information.
+
+4.Assign callback functions for (one) TTI event and for the reception
+of half of the slot of symbols (7 symbols) and Full slot of symbols
+14 symbols).
+
+5.Call xran_open() to initialize PRACH configuration, initialize DPDK,
+and launch xRAN timing thread.
+
+6.Call xran_start() to start processing xRAN packets for DL and UL.
+
+After this is complete 5G L1 runs with xRAN Front haul interface. During
+run time for every TTI event, the corresponding call back is called. For
+packet reception on UL direction, the corresponding call back is called.
+OTA time information such as frame id, subframe id and slot id can be
+obtained as result synchronization of the L1 pipeline to GPS time is
+performed.
+
+To stop and close the interface, perform this sequence of steps:
+
+7.Call xran_stop() to stop the processing of DL and UL.
+
+8.Call xran_close() to remove usage of xRAN resources.
+
+9.Call xran_mm_destroy() to destroy memory management subsystem.
+
+After this session is complete, a restart of the full L1 application is
+required. The current version of the library does not support multiple
+sessions without a restart of the full L1 application.
+
+
+~~~~~~~~~~~~~
+
+The xRAN library configuration is provided in the set of structures,
+such as struct xran_fh_init and struct xran_fh_config. The sample
+application gives an example of a test configuration used for mmWave.
+
+Some configuration options are not used in the Bronze Release and are reserved
+for future use.
+
+The following options are available: 
+
+**Structure** struct xran_fh_init\ **:**
+
+-  Number of CC and corresponding settings for each
+
+-  Core allocation for xRAN
+
+-  Ethernet port allocation
+
+-  O-DU and RU Ethernet Mac address
+
+-  Timing constraints of O-DU and 0-RU
+
+-  Debug features
+
+**Structure** struct xran_fh_config\ **:**
+
+-  Number of eAxC
+
+-  TTI Callback function and parameters
+
+-  PRACH 5G NR specific settings
+
+-  TDD frame configuration
+
+-  BBU specific configuration
+
+-  RU specific configuration
+
+**From an implementation perspective:**
+
+xran_init() performs init of the xRAN library and interface according to
+struct xran_fh_init information as per the start of application
+configuration.:
+
+-  Init DPDK with corresponding networking ports and core assignment
+
+-  Init mbuf pools
+
+-  Init DPDK timers and DPDK rings for internal packet processing
+
+-  Instantiate ORAH FH thread doing
+
+-  Timing processing (xran_timing_source_thread())
+
+-  ETH PMD (process_dpdk_io())
+
+-  IO XRAN-PHY exchange (ring_processing_func())
+
+**xran_open()** performs additional configuration as per run scenario:
+
+-  PRACH configuration
+
+-  C-plane initialization
+
+The Function **xran_close()** performs free of resources and allows potential
+restart of front haul interface with a different scenario.
+
+Start/Stop
+~~~~~~~~~~
+
+The Functions **xran_start()/xran_stop()** enable/disable packet processing for
+both DL and UL. This triggers execution of callbacks into the L1
+application.
+
+Data Exchange
+~~~~~~~~~~~~~
+
+Exchange of IQ samples, as well as C-plane specific information, is
+performed using a set of buffers allocated by xRAN |br|
+library from DPDK
+memory and shared with the l1 application. Buffers are allocated as a
+standard mbuf structure and DPDK pools are used to manage the allocation
+and free resources. Shared buffers are allocated at the init stage and
+are expected to be reused within 80 TTIs (10 ms).
+
+The xRAN protocol requires U-plane IQ data to be transferred in network
+byte order, and the L1 application handles IQ sample data in CPU byte
+order, requiring a swap. The PHY BBU pooling tasks perform copy and byte
+order swap during packet processing.
+
+C-plane Information Settings
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The interface between the xRAN library and PHY is defined via struct
+xran_prb_map and similar to the data plane. The same mbuf memory is used
+to allocate memory map of PRBs for each TTI.
+
+/\* Beamforming weights for single stream for each PRBs given number of
+Antenna elements \*/
+
+struct xran_cp_bf_weight{
+
+int16_t nAntElmTRx; /* num TRX for this allocation \*/
+
+int8_t\* p_ext_section; /* pointer to form extType \*/
+
+int16_t ext_section_sz; /* extType section size \*/
+
+};
+
+struct xran_cp_bf_attribute{
+
+int16_t weight[4];
+
+};
+
+struct xran_cp_bf_precoding{
+
+int16_t weight[4];
+
+};
+
+/\* section descriptor for given number of PRBs used on U-plane packet
+creation \*/
+
+struct xran_section_desc {
+
+uint16_t section_id; /* section id used for this element \*/
+
+int16_t iq_buffer_offset; /* Offset in bytes for the content of IQs
+with in main symb buffer \*/
+
+int16_t iq_buffer_len; /* Length in bytes for the content of IQs with
+in main symb buffer \*/
+
+uint8_t \*pData; /* optional pointer to data buffer \*/
+
+void \*pCtrl; /* optional poitner to mbuf \*/
+
+};
+
+/* PRB element structure \*/
+
+struct xran_prb_elm {
+
+int16_t nRBStart; /* start RB of RB allocation \*/
+
+int16_t nRBSize; /* number of RBs used \*/
+
+int16_t nStartSymb; /* start symbol ID \*/
+
+int16_t numSymb; /* number of symbols \*/
+
+int16_t nBeamIndex; /* beam index for given PRB \*/
+
+int16_t bf_weight_update; /* need to update beam weights or not \*/
+
+int16_t compMethod; /* compression index for given PRB \*/
+
+int16_t iqWidth; /* compression bit width for given PRB \*/
+
+int16_t BeamFormingType; /* index based, weights based or
+attribute-based beam forming*/
+
+struct xran_section_desc \* p_sec_desc[XRAN_NUM_OF_SYMBOL_PER_SLOT];
+/* section desctiptors to U-plane data given RBs \*/
+
+struct xran_cp_bf_weight bf_weight; /* beam forming information
+relevant for given RBs \*/
+
+union {
+
+struct xran_cp_bf_attribute bf_attribute;
+
+struct xran_cp_bf_precoding bf_precoding;
+
+};
+
+};
+
+/* PRB map structure \*/
+
+struct xran_prb_map {
+
+uint8_t dir; /* DL or UL direction \*/
+
+uint8_t xran_port; /* xran id of given RU [0-(XRAN_PORTS_NUM-1)] \*/
+
+uint16_t band_id; /* xran band id \*/
+
+uint16_t cc_id; /* componnent carrier id [0 - (XRAN_MAX_SECTOR_NR-1)]
+\*/
+
+uint16_t ru_port_id; /* RU device antenna portid [0 -
+(XRAN_MAX_ANTENNA_NR-1)*/
+
+uint16_t tti_id; /* xRAN slot id [0 - (max tti-1)] \*/
+
+uint8_t start_sym_id; /* start symbol Id [0-13] \*/
+
+uint32_t nPrbElm; /* total number of PRB elements for given map [0-
+(XRAN_MAX_PRBS-1)] \*/
+
+struct xran_prb_elm prbMap[XRAN_MAX_PRBS];
+
+};
+
+For the Bronze release C-plane sections are expected to be provided by L1
+pipeline. If 100% of RBs allocated at all times single element of RB map
+is expected to be allocated across all symbols. Dynamic RB allocation is
+performed base on C-plane configuration.
+
+The xRAN library will require that the content of the PRB map should be
+sorted in increasing order of PRB first and then symbols.
+
+Memory Management
+-----------------
+
+Memory used for the exchange of IQ data as well as control information,
+is controlled by the xRAN library. L1 application at the init stage
+performs:
+
+-  init memory management subsystem
+
+-  init buffer management subsystem (via DPDK pools)
+
+-  allocate buffers (mbuf) for each CC, antenna, symbol, and direction \
+   (DL, UL, PRACH) for XRAN_N_FE_BUF_LEN TTIs.
+
+-  buffers are reused for every XRAN_N_FE_BUF_LEN TTIs
+
+After the session is completed, the application can free buffers and
+destroy the memory management subsystem.
+
+From an implementation perspective, the xRAN library uses a standard
+mbuf primitive and allocates a pool of buffers for each sector. This
+function is performed using rte_pktmbuf_pool_create(),
+rte_pktmbuf_alloc(), rte_pktmbuf_append() to allocate one buffer per
+symbol for the mmWave case. More information on mbuf and DPDK pools can
+be found in the DPDK documentation.
+
+In the current implementation, mbuf, the number of buffers shared with
+the L1 application is the same number of buffers used to send to and
+receive from the Ethernet port. Memory copy operations are not required
+if the packet size is smaller than or equal to MTU. Future versions of
+the xRAN library are required to remove the memory copy requirement for
+packets where the size larger than MTU.
+
+External Interface Memory
+~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The xRAN library header file defines a set of structures to simplify
+access to memory buffers used for IQ data.
+
+struct xran_flat_buffer {
+
+uint32_t nElementLenInBytes;
+
+uint32_t nNumberOfElements;
+
+uint32_t nOffsetInBytes;
+
+uint32_t nIsPhyAddr;
+
+uint8_t \*pData;
+
+void \*pCtrl;
+
+};
+
+struct xran_buffer_list {
+
+uint32_t nNumBuffers;
+
+struct xran_flat_buffer \*pBuffers;
+
+void \*pUserData;
+
+void \*pPrivateMetaData;
+
+};
+
+typedef struct {
+
+int32_t bValid ;
+
+int32_t nSegToBeGen;
+
+int32_t nSegGenerated;
+
+int32_t nSegTransferred;
+
+struct rte_mbuf \*pData[N_MAX_BUFFER_SEGMENT];
+
+struct xran_buffer_list sBufferList;
+
+} BbuIoBufCtrlStruct;
+
+There is no explicit requirement for user to organize a set of buffers
+in this particular way. From a compatibility |br|
+perspective it is useful to
+follow the existing design of the 5G NR l1app used for Front Haul FPGA
+and define structures shared between l1 and xRAN lib as shown:
+
+/\* io struct \*/
+
+BbuIoBufCtrlStruct
+sFrontHaulTxBbuIoBufCtrl[XRAN_N_FE_BUF_LEN][XRAN_MAX_SECTOR_NR]\
+[XRAN_MAX_ANTENNA_NR];
+
+BbuIoBufCtrlStruct
+sFrontHaulTxPrbMapBbuIoBufCtrl[XRAN_N_FE_BUF_LEN][XRAN_MAX_SECTOR_NR][XRAN_MAX_ANTENNA_NR];
+
+BbuIoBufCtrlStruct
+sFrontHaulRxBbuIoBufCtrl[XRAN_N_FE_BUF_LEN][XRAN_MAX_SECTOR_NR][XRAN_MAX_ANTENNA_NR];
+
+BbuIoBufCtrlStruct
+sFrontHaulRxPrbMapBbuIoBufCtrl[XRAN_N_FE_BUF_LEN][XRAN_MAX_SECTOR_NR][XRAN_MAX_ANTENNA_NR];
+
+BbuIoBufCtrlStruct
+sFHPrachRxBbuIoBufCtrl[XRAN_N_FE_BUF_LEN][XRAN_MAX_SECTOR_NR][XRAN_MAX_ANTENNA_NR];
+
+/\* Cat B \*/
+
+BbuIoBufCtrlStruct
+sFHSrsRxBbuIoBufCtrl[XRAN_N_FE_BUF_LEN][XRAN_MAX_SECTOR_NR][XRAN_MAX_ANT_ARRAY_ELM_NR];
+
+/\* buffers list \*/
+
+struct xran_flat_buffer
+sFrontHaulTxBuffers[XRAN_N_FE_BUF_LEN][XRAN_MAX_SECTOR_NR][XRAN_MAX_ANTENNA_NR][XRAN_NUM_OF_SYMBOL_PER_SLOT];
+
+struct xran_flat_buffer
+sFrontHaulTxPrbMapBuffers[XRAN_N_FE_BUF_LEN][XRAN_MAX_SECTOR_NR][XRAN_MAX_ANTENNA_NR][XRAN_NUM_OF_SYMBOL_PER_SLOT];
+
+struct xran_flat_buffer
+sFrontHaulRxBuffers[XRAN_N_FE_BUF_LEN][XRAN_MAX_SECTOR_NR][XRAN_MAX_ANTENNA_NR][XRAN_NUM_OF_SYMBOL_PER_SLOT];
+
+struct xran_flat_buffer
+sFrontHaulRxPrbMapBuffers[XRAN_N_FE_BUF_LEN][XRAN_MAX_SECTOR_NR][XRAN_MAX_ANTENNA_NR][XRAN_NUM_OF_SYMBOL_PER_SLOT];
+
+struct xran_flat_buffer
+sFHPrachRxBuffers[XRAN_N_FE_BUF_LEN][XRAN_MAX_SECTOR_NR][XRAN_MAX_ANTENNA_NR][XRAN_NUM_OF_SYMBOL_PER_SLOT];
+
+/\* Cat B SRS buffers \*/
+
+struct xran_flat_buffer
+sFHSrsRxBuffers[XRAN_N_FE_BUF_LEN][XRAN_MAX_SECTOR_NR][XRAN_MAX_ANT_ARRAY_ELM_NR][XRAN_MAX_NUM_OF_SRS_SYMBOL_PER_SLOT];
+
+Doxygen file and xran_fh_o_du.h provide more details on the definition
+and usage of these structures.
+
+xRAN Specific Functionality
+---------------------------
+
+Front haul interface implementation in the general case is abstracted
+away using the interface defined in xran_fh_o_du.h
+
+The L1 application is not required to access xRAN protocol primitives
+(eCPRI header, application header, and others) directly. It is
+recommended to use the interface to remove dependencies between
+different software modules such as the l1 pipeline and xRAN library.
+
+External API
+~~~~~~~~~~~~
+
+The U-plane and C-plane APIs can be used directly from the application
+if such an option is required. The set of header files can be exported
+and called directly.
+
+xran_fh_o_du.h – xRAN main header file for O-DU scenario
+
+xran_cp_api.h – Control plane functions
+
+xran_pkt_cp.h – xRAN control plane packet definition
+
+xran_pkt.h – xRAN packet definition
+
+xran_pkt_up.h – xRAN User plane packet definition
+
+xran_sync_api.h – api functions to check PTP status
+
+xran_timer.h – API for timing
+
+xran_transport.h – eCPRI transport layer definition and api
+
+xran_up_api.h – user plane functions and definitions
+
+xran_compression.h – interface to compression/decompression functions
+
+Doxygen files provide detailed information on functions and structures
+available.
+
+.. _c-plane-1:
+
+C-plane
+~~~~~~~
+
+Implementation of the C-plane set of functions is defined in
+xran_cp_api.c and is used to prepare the content of C-plane packets
+according to the given configuration. Users can enable/disable
+generation of C-plane messages using enableCP field in struct
+xran_fh_init structure during init of ORAN front haul. The time of
+generation of C-plane message for DL and UL is done “Slot-based,” and
+timing can be controlled using O-DU settings according to Table 4.
+
+The C-plane module contains:
+
+-  initialization of C-plane database to keep track of allocation of
+   resources
+
+-  code to prepare C-plane packet for TX (O-DU)
+
+-  eCPRI header
+
+-  append radio application header
+
+-  append control section header
+
+-  append control section
+
+-  parser of C-plane packet for RX (O-RU emulation)
+
+-  parses and checks Section 1 and Section 3 packet content
+
+Sending and receiving packets is performed using xRAN ethdi sublayer
+functions.
+
+Creating a C-Plane Packet
+^^^^^^^^^^^^^^^^^^^^^^^^^
+
+API and Data Structures
+'''''''''''''''''''''''
+
+A C-Plane message can be composed using the following API:
+
+int xran_prepare_ctrl_pkt(struct rte_mbuf \*mbuf,
+
+struct xran_cp_gen_params \*params,
+
+uint8_t CC_ID, uint8_t Ant_ID, uint8_t seq_id);
+
+mbuf is the pointer of a DPDK packet buffer, which is allocated from the
+caller.
+
+params are the pointer of the structure which has the parameters to
+create the message.
+
+CC_ID is the parameter to specify component carrier index, Ant_ID is the
+parameters to specify the antenna port index (RU port index).
+
+seq_id is the sequence index for the message.
+
+params, the parameters to create a C-Plane message are defined as the
+structure of xran_cp_gen_params with an |br|
+example given below:
+
+struct xran_cp_gen_params {
+
+uint8_t dir;
+
+uint8_t sectionType;
+
+uint16_t numSections;
+
+struct xran_cp_header_params hdr;
+
+struct xran_section_gen_info \*sections;
+
+};
+
+dir is the direction of the C-Plane message to be generated. Available
+parameters are defined as XRAN_DIR_UL and XRAN_DIR_DL.
+
+sectionType is the section type for C-Plane message to generate, as ORAN
+specification defines all sections in a C-Plane message shall have the
+same section type. If different section types are required, they shall
+be sent with separate C-Plane messages. Available types of sections are
+defined as XRAN_CP_SECTIONTYPE_x. Please refer to the Table 5-2 Section
+Types in chapter 5.4 of ORAN specification.
+
+numSections is the total number of sections to generate, i.e., the
+number of the array in sections (struct xran_section_gen_info).
+
+hdr is the structure to hold the information to generate the radio
+application and section header in the C-Plane message. It is defined as
+the structure of xran_cp_header_params. Not all parameters in this
+structure are used for the generation, and the required parameters are
+slightly different by the type of section, as described in Table 10 and
+Table 11.
+
+Table 10. struct xran_cp_header_params – Common Radio Application Header
+
++------------+---------------------------------------------+---------+
+|            | Description                                 | Remarks |
++============+=============================================+=========+
+| filterIdx  | Filter Index. Available values are defined  | 5.4.4.3 |
+|            | as XRAN_FILTERINDEX_xxxxx.                  |         |
++------------+---------------------------------------------+---------+
+| frameId    | Frame Index. It is modulo 256 of frame      | 5.4.4.4 |
+|            | number.                                     |         |
++------------+---------------------------------------------+---------+
+| subframeId | Sub-frame Index.                            | 5.4.4.5 |
++------------+---------------------------------------------+---------+
+| slotId     | Slot Index. The maximum number is 15, as    | 5.4.4.6 |
+|            | defined in the specification.               |         |
++------------+---------------------------------------------+---------+
+| startSymId | Start Symbol Index.                         | 5.4.4.7 |
++------------+---------------------------------------------+---------+
+
+Table 11. struct xran_cp_header_params – Section Specific Parameters
+
++----------+----------+----------+---------+---+---+---+---+----------+
+|          | Des\     | Section  | Remarks |   |   |   |   |          |
+|          | cription | Type     |         |   |   |   |   |          |
+|          |          | ap\      |         |   |   |   |   |          |
+|          |          | plicable |         |   |   |   |   |          |
++==========+==========+==========+=========+===+===+===+===+==========+
+|          |          | 0        | 1       | 3 | 5 | 6 | 7 |          |
++----------+----------+----------+---------+---+---+---+---+----------+
+| fftSize  | FFT size | X        |         | X |   |   |   | 5.4.4.13 |
+|          | in frame |          |         |   |   |   |   |          |
+|          | st\      |          |         |   |   |   |   |          |
+|          | ructure. |          |         |   |   |   |   |          |
+|          | A\       |          |         |   |   |   |   |          |
+|          | vailable |          |         |   |   |   |   |          |
+|          | values   |          |         |   |   |   |   |          |
+|          | are      |          |         |   |   |   |   |          |
+|          | defined  |          |         |   |   |   |   |          |
+|          | as       |          |         |   |   |   |   |          |
+|          | X\       |          |         |   |   |   |   |          |
+|          | RAN_FFTS\|          |         |   |   |   |   |          |
+|          | IZE_xxxx |          |         |   |   |   |   |          |
++----------+----------+----------+---------+---+---+---+---+----------+
+| Scs      | Su\      | X        |         | X |   |   |   | 5.4.4.13 |
+|          | bcarrier |          |         |   |   |   |   |          |
+|          | Spacing  |          |         |   |   |   |   |          |
+|          | in the   |          |         |   |   |   |   |          |
+|          | frame    |          |         |   |   |   |   |          |
+|          | st\      |          |         |   |   |   |   |          |
+|          | ructure. |          |         |   |   |   |   |          |
+|          | A\       |          |         |   |   |   |   |          |
+|          | vailable |          |         |   |   |   |   |          |
+|          | values   |          |         |   |   |   |   |          |
+|          | are      |          |         |   |   |   |   |          |
+|          | defined  |          |         |   |   |   |   |          |
+|          | as       |          |         |   |   |   |   |          |
+|          | XRAN_SCS\|          |         |   |   |   |   |          |          
+|          | _xxxx    |          |         |   |   |   |   |          |
++----------+----------+----------+---------+---+---+---+---+----------+
+| iqWidth  | I/Q bit  |          | X       | X | X |   |   | 5.4.4.10 |
+|          | width in |          |         |   |   |   |   |          |
+|          | user     |          |         |   |   |   |   | 6.3.3.13 |
+|          | data     |          |         |   |   |   |   |          |
+|          | com\     |          |         |   |   |   |   |          |
+|          | pression |          |         |   |   |   |   |          |
+|          | header.  |          |         |   |   |   |   |          |
+|          | Should   |          |         |   |   |   |   |          |
+|          | be set   |          |         |   |   |   |   |          |
+|          | by zero  |          |         |   |   |   |   |          |
+|          | for      |          |         |   |   |   |   |          |
+|          | 16bits   |          |         |   |   |   |   |          |
++----------+----------+----------+---------+---+---+---+---+----------+
+| compMeth | Com\     |          | X       | X | X |   |   | 5.4.4.10 |
+|          | pression |          |         |   |   |   |   |          |
+|          | Method   |          |         |   |   |   |   | 6.3.3.13 |
+|          | in user  |          |         |   |   |   |   |          |
+|          | data     |          |         |   |   |   |   |          |
+|          | com\     |          |         |   |   |   |   |          |
+|          | pression |          |         |   |   |   |   |          |
+|          | header.  |          |         |   |   |   |   |          |
+|          | A\       |          |         |   |   |   |   |          |
+|          | vailable |          |         |   |   |   |   |          |
+|          | values   |          |         |   |   |   |   |          |
+|          | are      |          |         |   |   |   |   |          |
+|          | defined  |          |         |   |   |   |   |          |
+|          | as       |          |         |   |   |   |   |          |
+|          | XRAN\    |          |         |   |   |   |   |          |
+|          | _COMPMET\|          |         |   |   |   |   |          |
+|          | HOD_xxxx |          |         |   |   |   |   |          |
++----------+----------+----------+---------+---+---+---+---+----------+
+| numUEs   | Number   |          |         |   |   | X |   | 5.4.4.11 |
+|          | of UEs.  |          |         |   |   |   |   |          |
+|          | Applies  |          |         |   |   |   |   |          |
+|          | to       |          |         |   |   |   |   |          |
+|          | section  |          |         |   |   |   |   |          |
+|          | type 6   |          |         |   |   |   |   |          |
+|          | and not  |          |         |   |   |   |   |          |
+|          | s\       |          |         |   |   |   |   |          |
+|          | upported |          |         |   |   |   |   |          |
+|          | in this  |          |         |   |   |   |   |          |
+|          | release. |          |         |   |   |   |   |          |
++----------+----------+----------+---------+---+---+---+---+----------+
+| ti\      | Time     | X        |         | X |   |   |   | 5.4.4.12 |
+| meOffset | Offset.  |          |         |   |   |   |   |          |
+|          | Time     |          |         |   |   |   |   |          |
+|          | offset   |          |         |   |   |   |   |          |
+|          | from the |          |         |   |   |   |   |          |
+|          | start of |          |         |   |   |   |   |          |
+|          | the slot |          |         |   |   |   |   |          |
+|          | to start |          |         |   |   |   |   |          |
+|          | of       |          |         |   |   |   |   |          |
+|          | Cyclic   |          |         |   |   |   |   |          |
+|          | Prefix.  |          |         |   |   |   |   |          |
++----------+----------+----------+---------+---+---+---+---+----------+
+| cpLength | Cyclic   | X        |         | X |   |   |   | 5.4.4.14 |
+|          | Prefix   |          |         |   |   |   |   |          |
+|          | Length.  |          |         |   |   |   |   |          |
++----------+----------+----------+---------+---+---+---+---+----------+
+
+**Only sections types 1 and 3 are supported in the current release.**
+
+Sections are the pointer to the array of structure which has the
+parameters for section(s) and it is defined as below:
+
+struct xran_section_gen_info {
+
+struct xran_section_info info;
+
+uint32_t exDataSize;
+
+struct {
+
+uint16_t type;
+
+uint16_t len;
+
+void \*data;
+
+} exData[XRAN_MAX_NUM_EXTENSIONS];
+
+};
+
+info is the structure to hold the information to generate section and it
+is defined as the structure of xran_section_info. Like
+xran_cp_header_params, all parameters are not required to generate
+section and Table 12 describes which |br|
+parameters are required for each
+section.
+
+Table 12. Parameters for Sections
+
++-------+-------+-------+-------+-------+-------+-------+-------+
+|       | D\    | Se\   | Re\   |       |       |       |       |
+|       | escri\| ction | marks |       |       |       |       |
+|       | ption | Type  |       |       |       |       |       |
+|       |       | appli\|       |       |       |       |       |
+|       |       | cable |       |       |       |       |       |
++=======+=======+=======+=======+=======+=======+=======+=======+
+|       |       | 0     | 1     | 3     | 5     | 6     |       |
++-------+-------+-------+-------+-------+-------+-------+-------+
+| Id    | Se\   | **X** | **X** | **X** | **X** | **X** | 5.\   |
+|       | ction |       |       |       |       |       | 4.5.1 |
+|       | I\    |       |       |       |       |       |       |
+|       | denti\|       |       |       |       |       |       |
+|       | fier. |       |       |       |       |       |       |
++-------+-------+-------+-------+-------+-------+-------+-------+
+| Rb    | Res\  | **X** | **X** | **X** | **X** | **X** | 5.\   |
+|       | ource |       |       |       |       |       | 4.5.2 |
+|       | Block\|       |       |       |       |       |       |
+|       | Indic\|       |       |       |       |       |       |
+|       | ator. |       |       |       |       |       |       |
+|       | Avai\ |       |       |       |       |       |       |
+|       | lable |       |       |       |       |       |       |
+|       | v\    |       |       |       |       |       |       |
+|       | alues |       |       |       |       |       |       |
+|       | are   |       |       |       |       |       |       |
+|       | de\   |       |       |       |       |       |       |
+|       | fined |       |       |       |       |       |       |
+|       | as    |       |       |       |       |       |       |
+|       | XRAN\ |       |       |       |       |       |       |
+|       | _\    |       |       |       |       |       |       |
+|       | RBI\  |       |       |       |       |       |       |
+|       | ND_xx\|       |       |       |       |       |       |
+|       | xx.   |       |       |       |       |       |       |
++-------+-------+-------+-------+-------+-------+-------+-------+
+| s\    | S\    | **X** | **X** | **X** | **X** | **X** | 5.\   |
+| ymInc | ymbol |       |       |       |       |       | 4.5.3 |
+|       | n\    |       |       |       |       |       |       |
+|       | umber |       |       |       |       |       |       |
+|       | Incr\ |       |       |       |       |       |       |
+|       | ement |       |       |       |       |       |       |
+|       | com\  |       |       |       |       |       |       |
+|       | mand. |       |       |       |       |       |       |
+|       | Avai\ |       |       |       |       |       |       |
+|       | lable |       |       |       |       |       |       |
+|       | v\    |       |       |       |       |       |       |
+|       | alues |       |       |       |       |       |       |
+|       | are   |       |       |       |       |       |       |
+|       | de\   |       |       |       |       |       |       |
+|       | fined |       |       |       |       |       |       |
+|       | as    |       |       |       |       |       |       |
+|       | XRA\  |       |       |       |       |       |       |
+|       | N_SYM\|       |       |       |       |       |       |
+|       | BOL\  |       |       |       |       |       |       |
+|       | NUMBE\|       |       |       |       |       |       |
+|       | R_xx\ |       |       |       |       |       |       |
+|       | xx.   |       |       |       |       |       |       |
++-------+-------+-------+-------+-------+-------+-------+-------+
+| star\ | Sta\  | **X** | **X** | **X** | **X** | **X** | 5.\   |
+| tPrbc | rting\|       |       |       |       |       | 4.5.4 |
+|       | PRB   |       |       |       |       |       |       |
+|       | of    |       |       |       |       |       |       |
+|       | data  |       |       |       |       |       |       |
+|       | se\   |       |       |       |       |       |       |
+|       | ction |       |       |       |       |       |       |
+|       | de\   |       |       |       |       |       |       |
+|       | scrip\|       |       |       |       |       |       |
+|       | tion. |       |       |       |       |       |       |
++-------+-------+-------+-------+-------+-------+-------+-------+
+| nu    | The   | **X** | **X** | **X** | **X** | **X** | 5.\   |
+| mPrbc | n\    |       |       |       |       |       | 4.5.6 |
+|       | umber |       |       |       |       |       |       |
+|       | of    |       |       |       |       |       |       |
+|       | conti\|       |       |       |       |       |       |
+|       | guous |       |       |       |       |       |       |
+|       | PRBs  |       |       |       |       |       |       |
+|       | per   |       |       |       |       |       |       |
+|       | data  |       |       |       |       |       |       |
+|       | se\   |       |       |       |       |       |       |
+|       | ction |       |       |       |       |       |       |
+|       | de\   |       |       |       |       |       |       |
+|       | scrip\|       |       |       |       |       |       |
+|       | tion. |       |       |       |       |       |       |
+|       | When  |       |       |       |       |       |       |
+|       | nu\   |       |       |       |       |       |       |
+|       | mPrbc |       |       |       |       |       |       |
+|       | is    |       |       |       |       |       |       |
+|       | gr\   |       |       |       |       |       |       |
+|       | eater |       |       |       |       |       |       |
+|       | than  |       |       |       |       |       |       |
+|       | 255,  |       |       |       |       |       |       |
+|       | it    |       |       |       |       |       |       |
+|       | will  |       |       |       |       |       |       |
+|       | be    |       |       |       |       |       |       |
+|       | conv\ |       |       |       |       |       |       |
+|       | erted |       |       |       |       |       |       |
+|       | to    |       |       |       |       |       |       |
+|       | zero  |       |       |       |       |       |       |
+|       | by    |       |       |       |       |       |       |
+|       | the   |       |       |       |       |       |       |
+|       | macro |       |       |       |       |       |       |
+|       | (XR\  |       |       |       |       |       |       |
+|       | AN_CO\|       |       |       |       |       |       |
+|       | NVERT\|       |       |       |       |       |       |
+|       | _NUMP\|       |       |       |       |       |       |
+|       | RBC). |       |       |       |       |       |       |
++-------+-------+-------+-------+-------+-------+-------+-------+
+| r\    | Res\  | **X** | **X** | **X** | **X** |       | 5.\   |
+| eMask | ource\|       |       |       |       |       | 4.5.5 |
+|       | El\   |       |       |       |       |       |       |
+|       | ement\|       |       |       |       |       |       |
+|       | Mask. |       |       |       |       |       |       |
++-------+-------+-------+-------+-------+-------+-------+-------+
+| numS\ | N\    | **X** | **X** | **X** | **X** |       | 5.\   |
+| ymbol | umber |       |       |       |       |       | 4.5.7 |
+|       | of    |       |       |       |       |       |       |
+|       | Sym\  |       |       |       |       |       |       |
+|       | bols. |       |       |       |       |       |       |
++-------+-------+-------+-------+-------+-------+-------+-------+
+| b\    | Beam\ |       | **X** | **X** |       |       | 5.\   |
+| eamId | I\    |       |       |       |       |       | 4.5.9 |
+|       | denti\|       |       |       |       |       |       |
+|       | fier. |       |       |       |       |       |       |
++-------+-------+-------+-------+-------+-------+-------+-------+
+| freqO\| Freq\ |       |       | **X** |       |       | 5.4\  |
+| ffset | uency\|       |       |       |       |       | .5.11 |
+|       | Of\   |       |       |       |       |       |       |
+|       | fset. |       |       |       |       |       |       |
++-------+-------+-------+-------+-------+-------+-------+-------+
+| ueId  | UE\   |       |       |       | **X** | **X** | 5.4\  |
+|       | i\    |       |       |       |       |       | .5.10 |
+|       | denti\|       |       |       |       |       |       |
+|       | fier. |       |       |       |       |       |       |
+|       | Not   |       |       |       |       |       |       |
+|       | supp\ |       |       |       |       |       |       |
+|       | orted |       |       |       |       |       |       |
+|       | in    |       |       |       |       |       |       |
+|       | this  |       |       |       |       |       |       |
+|       | rel\  |       |       |       |       |       |       |
+|       | ease. |       |       |       |       |       |       |
++-------+-------+-------+-------+-------+-------+-------+-------+
+| regF\ | Regu\ |       |       |       |       | **X** | 5.4\  |
+| actor | lariz\|       |       |       |       |       | .5.12 |
+|       | ation |       |       |       |       |       |       |
+|       | Fa\   |       |       |       |       |       |       |
+|       | ctor. |       |       |       |       |       |       |
+|       | Not   |       |       |       |       |       |       |
+|       | supp\ |       |       |       |       |       |       |
+|       | orted |       |       |       |       |       |       |
+|       | in    |       |       |       |       |       |       |
+|       | this  |       |       |       |       |       |       |
+|       | re\   |       |       |       |       |       |       |
+|       | lease |       |       |       |       |       |       |
++-------+-------+-------+-------+-------+-------+-------+-------+
+| Ef    | Exte\ |       | **X** | **X** | **X** | **X** | 5.\   |
+|       | nsion |       |       |       |       |       | 4.5.8 |
+|       | Flag. |       |       |       |       |       |       |
+|       | Not   |       |       |       |       |       |       |
+|       | supp\ |       |       |       |       |       |       |
+|       | orted |       |       |       |       |       |       |
+|       | in    |       |       |       |       |       |       |
+|       | this  |       |       |       |       |       |       |
+|       | rel\  |       |       |       |       |       |       |
+|       | ease. |       |       |       |       |       |       |
++-------+-------+-------+-------+-------+-------+-------+-------+
+
+**Only sections types 1 and 3 are supported in the current release.**
+
+**The xran_section_info has more parameters – type, startSymId, iqWidth,
+compMeth. These are the same parameters as those of radio application
+or section header but need to be copied into this structure again for
+the section data base.**
+
+exDataSize and exData are used to add section extensions for the
+section.
+
+exDataSize is the number of elements in the exData array. The maximum
+number of elements is defined as XRAN_MAX_NUM_EXTENSIONS and it is
+defined by four in this release with the assumption that four different
+types of section extensions can be added to a section (section extension
+type 3 is excluded since it is not supported). exData.type is the type
+of section extension and exData.len is the length of structure of
+section extension parameter in exData.data. exData.data is the pointer
+to the structure of section extensions and different structures are used
+by the type of section extensions like below.
+
+struct xran_sectionext1_info {
+
+uint16_t rbNumber; /* number RBs to ext1 chain \*/
+
+uint16_t bfwNumber; /* number of bf weights in this section \*/
+
+uint8_t bfwiqWidth;
+
+uint8_t bfwCompMeth;
+
+int16_t \*p_bfwIQ; /* pointer to formed section extention \*/
+
+int16_t bfwIQ_sz; /* size of buffer with section extention information
+\*/
+
+union {
+
+uint8_t exponent;
+
+uint8_t blockScaler;
+
+uint8_t compBitWidthShift;
+
+uint8_t activeBeamspaceCoeffMask[XRAN_MAX_BFW_N]; /\* ceil(N/8)*8,
+should be multiple of 8 \*/
+
+} bfwCompParam;
+
+};
+
+For section extension type 1, the structure of xran_sectionext1_info is
+used. Please note that the xRAN library will use bfwIQ (beamforming
+weight) as-is, i.e., xRAN library will not perform the compression, so
+the user should provide proper data to bfwIQ.
+
+struct xran_sectionext2_info {
+
+uint8_t bfAzPtWidth;
+
+uint8_t bfAzPt;
+
+uint8_t bfZePtWidth;
+
+uint8_t bfZePt;
+
+uint8_t bfAz3ddWidth;
+
+uint8_t bfAz3dd;
+
+uint8_t bfZe3ddWidth;
+
+uint8_t bfZe3dd;
+
+uint8_t bfAzSI;
+
+uint8_t bfZeSI;
+
+};
+
+For section extension type 2, the structure of xran_sectionext2_info is
+used. Each parameter will be packed as specified bit width.
+
+struct xran_sectionext4_info {
+
+uint8_t csf;
+
+uint8_t pad0;
+
+uint16_t modCompScaler;
+
+};
+
+For section extension type 4, the structure of xran_sectionext4_info is
+used.
+
+struct xran_sectionext5_info {
+
+uint8_t num_sets;
+
+struct {
+
+uint16_t csf;
+
+uint16_t mcScaleReMask;
+
+uint16_t mcScaleOffset;
+
+} mc[XRAN_MAX_MODCOMP_ADDPARMS];
+
+};
+
+For section extension type 5, the structure of xran_sectionext5_info is
+used. Please note that current implementation supports maximum two sets
+of additional parameters.
+
+**Section extensions type 3 is not supported since it is LTE specific.**
+
+Section Extensions are not fully verified in this release.
+
+Detail Procedures in API
+''''''''''''''''''''''''
+
+xran_prepare_ctrl_pkt() has several procedures to compose a C-Plane
+packet.
+
+1. Append transport header
+
+-  Reserve eCPRI header space in the packet buffer
+
+-  eCPRI version is fixed by XRAN_ECPRI_VER (0x0001)
+
+-  Concatenation and transport layer fragmentation is not supported.
+
+   ecpri_concat=0, ecpri_seq_id.sub_seq_id=0 and ecpri_seq_id.e_bit=1
+
+-  The caller needs to provide a component carrier index, antenna index,
+   and message identifier through function arguments.
+
+   CC_ID, Ant_ID and seq_id
+
+-  ecpriRtcid (ecpri_xtc_id) is composed with CC_ID and Ant_ID by
+   xran_compose_cid.
+
+-  DU port ID and band sector ID are fixed by zero in this release.
+
+-  The output of xran_compose_cid is stored in network byte order.
+
+-  The length of the payload is initialized by zero.
+
+2. Append radio application header:
+
+-  xran_append_radioapp_header() checks the type of section through
+   params->sectionType and determines proper function to append
+   remaining header components.
+
+-  Only section type 1 and 3 are supported, returns
+   XRAN_STATUS_INVALID_PARAM for other types.
+
+-  Each section uses a different function to compose the remaining
+   header and size to calculate the total length in the transport
+   header.
+
+For section type 1, xran_prepare_section1_hdr() and sizeof(struct
+xran_cp_radioapp_section1_header)
+
+For section type 3, xran_prepare_section3_hdr() and sizeof(struct
+xran_cp_radioapp_section3_header)
+
+-  Reserves the space of common radio application header and composes
+   header by xran_prepare_radioapp_common_header().
+
+-  The header is stored in network byte order.
+
+-  Appends remaining header components by the selected function above
+
+-  The header is stored in network byte order
+
+3. Append section header and section
+
+-  xran_append_control_section() determines proper size and function to
+   append section header and contents.
+
+-  For section type 1, xran_prepare_section1() and sizeof(struct
+   xran_cp_radioapp_section1)
+
+-  For section type 3, xran_prepare_section3() and sizeof(struct
+   xran_cp_radioapp_section3)
+
+-  Appends section header and section(s) by selected function above.
+
+-  If multiple sections are configured, then those will be added.
+
+-  Since fragmentation is not considered in this implementation, the
+   total length of a single C-Plane message shall not exceed MTU
+   size.
+
+-  The header and section(s) are stored in network byte order.
+
+-  Appends section extensions if it is set (ef=1)
+
+-  xran_append_section_extensions() adds all configured extensions by
+   its type.
+
+-  xran_prepare_sectionext_x() (x = 1,2,4,5) will be called by the
+   type from xran_append_section_extensions() and these functions
+   will create extension field.
+
+**Example Usage of API**
+''''''''''''''''''''''''
+
+There are two reference usages of API to generate C-Plane message in
+lib/src/xran_common.c
+
+-  generate_cpmsg_dlul()
+
+-  generate_cpmsg_prach()
+
+generate_cpmsg_dlul() is to generate the C-Plane message with section
+type 1 for DL or UL symbol data scheduling.
+
+This function has hardcoded values for some parameters such as:
+
+-  The filter index is fixed to XRAN_FILTERINDEX_STANDARD.
+
+-  RB indicator is fixed to XRAN_RBIND_EVERY.
+
+-  Symbol increment is not used (XRAN_SYMBOLNUMBER_NOTINC)
+
+-  Resource Element Mask is fixed to 0xfff
+
+The extension is not used.
+
+After C-Plane message generation, API send_cpmsg() is called. This
+function also includes the implementation for these capabilities:
+
+-  Send the generated packet to the TX ring after adding an Ethernet
+   header.
+
+-  Add section information of generated C-Plane packet to section
+   database, to generate U-plane message by C-Plane configuration
+
+send_cpmsg_prach() is to generate the C-Plane message with section type
+3 for PRACH scheduling.
+
+This functions also has some hardcoded values for the following
+parameters:
+
+-  RB indicator is fixed to XRAN_RBIND_EVERY.
+
+-  Symbol increment is not used (XRAN_SYMBOLNUMBER_NOTINC).
+
+-  Resource Element Mask is fixed to 0xfff.
+
+And similar to generate_cpmsg_dlul(), after this function generates the
+message, send_cpmsg() sends the generated packet to the TX ring and adds
+section information of the packet to the section database. Checking and
+parsing received PRACH symbol data by section information from the
+C-Plane are not implemented in this release.
+
+Example Configuration of C-Plane Messages
+'''''''''''''''''''''''''''''''''''''''''
+
+C-Plane messages can be composed through API, and the sample application
+shows several reference usages of the configuration for different
+numerologies.
+
+Below are the examples of C-Plane message configuration with a sample
+application for mmWave – numerology 3, 100 MHz bandwidth, TDD (DDDS)
+
+**C-Plane Message – downlink symbol data for a downlink slot**
+
+-  Single CP message with the single section of section type 1
+
+-  Configures single CP message for all consecutive downlink symbols
+
+-  Configures whole RBs (66) for a symbol
+
+-  Compression and beamforming are not used
+
+**C-Plane Message – uplink symbol data for uplink slot**
+
+-  Single CP message with the single section of section type 1
+
+-  Configures single CP message for all consecutive uplink symbols (UL
+   symbol starts from 3)
+
+-  Configures whole RBs (66) for a symbol
+
+-  Compression and beamforming are not used
+
+**C-Plane Message – PRACH**
+
+-  Single CP message with the single section of section type 3 including
+   repetition
+
+-  Configures PRACH format A3, config index 81, and detail parameters
+   are:
+
+-  Filter Index : 3
+
+-  CP length : 0
+
+-  Time offset : 2026
+
+-  FFT size : 1024
+
+-  Subcarrier spacing : 120KHz
+
+-  Start symbol index : 7
+
+-  Number of symbols : 6
+
+-  Number of PRBCs : 12
+
+-  Frequency offset : -792
+
+-  Compression and beamforming are not used
+
+Functions to Store/Retrieve Section Information
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+There are several functions to store/retrieve section information of
+C-Plane messages. Since U-plane messages must be generated by the
+information in the sections of a C-Plane message, it is required to
+store and retrieve section |br|
+information.
+
+**APIs and Data Structure**
+'''''''''''''''''''''''''''
+
+APIs for initialization and release storage are:
+
+-  int xran_cp_init_sectiondb(void \*pHandle);
+
+-  int xran_cp_free_sectiondb(void \*pHandle);
+
+APIs to store and retrieve section information are:
+
+-  int xran_cp_add_section_info(void \*pHandle, uint8_t dir, uint8_t
+   cc_id, uint8_t ruport_id, uint8_t ctx_id, struct xran_section_info
+   \*info);
+
+-  int xran_cp_add_multisection_info(void \*pHandle, uint8_t cc_id,
+   uint8_t ruport_id, uint8_t ctx_id, struct xran_cp_gen_params
+   \*gen_info);
+
+-  struct xran_section_info \*xran_cp_find_section_info(void \*pHandle,
+   uint8_t dir, uint8_t cc_id, uint8_t ruport_id, uint8_t ctx_id,
+   uint16_t section_id);
+
+-  struct xran_section_info \*xran_cp_iterate_section_info(void
+   \*pHandle, uint8_t dir, uint8_t cc_id, uint8_t ruport_id, uint8_t
+   ctx_id, uint32_t \*next);
+
+-  int xran_cp_getsize_section_info(void \*pHandle, uint8_t dir, uint8_t
+   cc_id, uint8_t ruport_id, uint8_t ctx_id);
+
+APIs to reset the storage for a new slot are:
+
+-  int xran_cp_reset_section_info(void \*pHandle, uint8_t dir, uint8_t
+   cc_id, uint8_t ruport_id, uint8_t ctx_id);
+
+The structure of xran_section_info is used to store/retrieve
+information. This is the same structure used to generate a C-Plane
+message. Please refer to Section 5.4.2.1.1 for more details.
+
+The storage for section information is declared as a multi-dimensional
+array and declared as a local static variable to limit direct access.
+Each item is defined as the structure of xran_sectioninfo_db, and it has
+the number of stored section information items (cur_index) and the array
+of the information (list), as shown below.
+
+/*
+
+\* This structure to store the section information of C-Plane
+
+\* in order to generate and parse corresponding U-Plane \*/
+
+struct xran_sectioninfo_db {
+
+uint32_t cur_index; /* Current index to store for this eAXC \*/
+
+struct xran_section_info list[XRAN_MAX_NUM_SECTIONS]; /* The array of
+section information \*/
+
+};
+
+static struct xran_sectioninfo_db
+sectiondb[XRAN_MAX_SECTIONDB_CTX][XRAN_DIR_MAX][XRAN_COMPONENT_CARRIERS_MAX][XRAN_MAX_ANTENNA_NR*2
++ XRAN_MAX_ANT_ARRAY_ELM_NR];
+
+The maximum size of the array can be adjusted if required by system
+configuration. Since transmission and reception window of U-Plane can be
+overlapped with the start of new C-Plane for next slot, functions have
+context index to identify and protect the information. Currently the
+maximum number of context is defined by two and it can be adjusted if
+needed.
+
+8. Since the context index is not managed by the library and APIs are
+expecting it from the caller as a parameter, the caller shall
+consider a proper method to manage it to avoid corruption. The
+current reference implementation uses a slot and subframe index to
+calculate the context index.
+
+**Example Usage of APIs**
+'''''''''''''''''''''''''
+
+There are references to show the usage of APIs as below.
+
+-  Initialization and release:
+
+-  xran_cp_init_sectiondb(): xran_open() in lib/src/xran_main.c
+
+-  xran_cp_free_sectiondb(): xran_close() in lib/src/xran_main.c
+
+-  Store section information:
+
+-  xran_cp_add_section_info(): send_cpmsg_dlul() and
+   send_cpmsg_prach()in lib/src/xran_main.c
+
+-  Retrieve section information:
+
+-  xran_cp_iterate_section_info(): xran_process_tx_sym() in
+   lib/src/xran_main.c
+
+-  xran_cp_getsize_section_info(): xran_process_tx_sym() in
+   lib/src/xran_main.c
+
+-  Reset the storage for a new slot:
+
+-  xran_cp_reset_section_info(): tx_cp_dl_cb() and tx_cp_ul_cb() in
+   lib/src/xran_main.c
+
+**Function for RU emulation and Debug**
+'''''''''''''''''''''''''''''''''''''''
+
+xran_parse_cp_pkt() is a function which can be utilized for RU emulation
+or debug. It is defined below:
+
+int xran_parse_cp_pkt(struct rte_mbuf \*mbuf,
+
+struct xran_cp_gen_params \*result,
+
+struct xran_recv_packet_info \*pkt_info);
+
+It parses a received C-Plane packet and retrieves the information from
+its headers and sections.
+
+The retrieved information is stored in the structures:
+
+struct xran_cp_gen_params: section information from received C-Plane
+packet
+
+struct xran_recv_packet_info: transport layer header information (eCPRI
+header)
+
+These functions can be utilized to debug or RU emulation purposes.
+
+.. _u-plane-1:
+
+U-plane
+~~~~~~~
+
+Single Section is the default mode of xRAN packet creation. It assumes
+that there is only one section per packet, and all IQ samples are
+attached to it. Compression is not supported.
+
+A message is built in mbuf space given as a parameter. The library
+builds eCPRI header filling structure fields by taking the IQ sample
+size and populating a particular packet length and sequence number.
+
+Currently, the supported IQ bit width is 16.
+
+Implementation of a U-plane set of functions is defined in xran_up_api.c
+and is used to prepare U-plane packet content according to the given
+configuration.
+
+The following list of functions is implemented for U-plane:
+
+-  Build eCPRI header
+
+-  Build application header
+
+-  Build section header
+
+-  Append IQ samples to packet
+
+-  Prepare full symbol of xRAN data for single eAxC
+
+-  Process RX packet per symbol.
+
+The time of generation of a U-plane message for DL and UL is
+“symbol-based” and can be controlled using O-DU settings (O-RU),
+according to Table 4.
+
+Supporting Code
+---------------
+
+The xRAN library has a set of functions used to assist in packet
+processing and data exchange not directly used for xRAN packet
+processing.
+
+Timing
+~~~~~~
+
+The sense of time for the xRAN protocol is obtained from system time,
+where the system timer is synchronized to GPS time via PTP protocol
+using the Linux PHP package. On the software side, a simple polling loop
+is utilized to get time up to nanosecond precision and particular packet
+processing jobs are scheduled via the DPDK timer.
+
+long poll_next_tick(int interval)
+
+{
+
+struct timespec start_time;
+
+struct timespec cur_time;
+
+long target_time;
+
+long delta;
+
+clock_gettime(CLOCK_REALTIME, &start_time);
+
+target_time = (start_time.tv_sec \* NSEC_PER_SEC + start_time.tv_nsec +
+interval \* NSEC_PER_USEC) / (interval \* NSEC_PER_USEC) \* interval;
+
+while(1)
+
+{
+
+clock_gettime(CLOCK_REALTIME, &cur_time);
+
+delta = (cur_time.tv_sec \* NSEC_PER_SEC + cur_time.tv_nsec) -
+target_time \* NSEC_PER_USEC;
+
+if(delta > 0 \|\| (delta < 0 && abs(delta) < THRESHOLD))
+
+{
+
+break;
+
+}
+
+}
+
+return delta;
+
+}
+
+Polling is used to achieve the required precision of symbol time. For
+example, in the mmWave scenario, the symbol time is 125µs/14=~8.9µs.
+Small deterministic tasks can be executed within the polling interval
+provided. It’s smaller than the symbol interval time.
+
+DPDK Timers
+~~~~~~~~~~~
+
+DPDK provides sets of primitives (struct rte_rimer) and functions
+(rte_timer_reset_sync() rte_timer_manage()) to |br|
+schedule processing of
+function as timer. The timer is based on the TSC clock and is not
+synchronized to PTP time. As a |br|
+result, this timer cannot be used as a
+periodic timer because the TSC clock can drift substantially relative to
+the system timer which in turn is synchronized to PTP (GPS)
+
+Only single-shot timers are used to schedule processing based on
+particular events such as symbol time. The packet |br|
+processing function
+calls rte_timer_manage() in the loop, and the resulting execution of
+timer function happens right |br|
+after the timer was “armed”.
+
+xRAN Ethernet
+~~~~~~~~~~~~~
+
+xran_init_port() function performs initialization of DPDK ETH port.
+Standard port configuration is used as per reference example from DPDK.
+
+Jumbo Frames are used by default. Mbufs size is extended to support 9600
+bytes packets.
+
+Mac address and VLAN tag are expected to be configured by Infrastructure
+software. See Appendix A.4.
+
+From an implementation perspective, modules provide functions to handle:
+
+-  Ethernet headers
+
+-  VLAN tag
+
+-  Send and Receive mbuf.
+
+xRAN Ethdi
+~~~~~~~~~~
+
+Ethdi provides functionality to work with the content of an Ethernet
+packet and dispatch processing to/from the xRAN layer. Ethdi
+instantiates a main PMD driver thread and dispatches packets between the
+ring and RX/TX using rte_eth_rx_burst() and rte_eth_tx_burst() DPDK
+functions.
+
+For received packets, it maintains a set of handlers for ethertype
+handlers and xRAN layer register one xRAN ethtype |br|
+0xAEFE, resulting in
+packets with this ethertype being routed to the xRAN processing
+function. This function checks the message type of the eCPRI header and
+dispatches packet to either C-plane processing or U-plane processing.
+
+Initialization of memory pools, allocation and freeing of mbuf for
+Ethernet packets occur in this layer.
+
+
+
+
+