OAI is open-source software that is being used for the experimentation, evaluation, development of current 3GPP wireless communication standards such as LTE and 5G, and several 3GPP proposals towards 5G and beyond. The current OAI implementation provide the following:
- Open source implementation of Radio Access Network(RAN) that includes gNB, eNB, UEs (4G and 5G).
- Open source implementation for Core Network(CN) for 4G and 5G
Currently, the OAI platform includes a full software implementation of the 3GPP 4G-LTE and 5G-NR protocol stack for:
- the RAN (OpenAirInterface5G) for 4G, 5G-NSA, and 5G-SA
- the EPC (OpenAirCN) for 4G.
- the 5G-CORE (5GC) for 5G.
- OpenAirInterface 4G-LTE eNB Feature Set
- gNB PHY Layer
- gNB MAC Layer
- gNB RLC Layer
- gNB PDCP Layer
- gNB RRC Layer
- gNB SDAP Layer
- gNB X2AP Layer
- gNB NGAP
- gNB F1AP
- gNB GTP-U
INFO
The following features are valid for the gNB and the 5G-NR UE.
- Static TDD,
- FDD
- Normal CP
- 30 kHz subcarrier spacing
- Bandwidths: 10, 20, 40, 80, 100MHz (273 Physical Resource Blocks)
- Intermediate downlink and uplink frequencies to interface with IF equipment
- Single antenna port (single beam)
- Slot format: 14 OFDM symbols in UL or DL
- Highly efficient 3GPP compliant LDPC encoder and decoder (BG1 and BG2 supported)
- Highly efficient 3GPP compliant polar encoder and decoder
- Encoder and decoder for short blocks
- Support for UL transform precoding (SC-FDMA)
- 30KHz SCS for FR1 and 120 KHz SCS for FR2
- Generation of NR-PSS/NR-SSS
- NR-PBCH supports multiple SSBs and flexible periodicity
- Generation of NR-PDCCH (including generation of DCI, polar encoding, scrambling, modulation, RB mapping, etc)
- common search space
- user-specific search space
- DCI formats: 00, 10, 01 and 11
- Generation of NR-PDSCH (including Segmentation, LDPC encoding, rate matching, scrambling, modulation, RB mapping, etc).
- PDSCH mapping type A and B
- DMRS configuration type 1 and 2
- Single and multiple DMRS symbols
- PTRS support
- Support for 1, 2 and 4 TX antennas
- Support for up to 2 layers (currently limited to DMRS configuration type 2)
- NR-CSIRS Generation of sequence at PHY
- NR-PUSCH (including Segmentation, LDPC encoding, rate matching, scrambling, modulation, RB mapping, etc).
- PUSCH mapping type A and B
- DMRS configuration type 1 and 2
- Single and multiple DMRS symbols
- PTRS support
- Support for 1 RX antenna
- Support for 1 layer
- NR-PUCCH
- Format 0 (2 bits, for ACK/NACK and SR)
- Format 2 (up to 11 bits, mainly for CSI feedback)
- NR-SRS
- SRS signal reception
- Channel estimation (with T tracer real time monitoring)
- Power noise estimation
- NR-PRACH
- Formats 0,1,2,3, A1-A3, B1-B3
- Highly efficient 3GPP compliant LDPC encoder and decoder (BG1 and BG2 are supported)
- Highly efficient 3GPP compliant polar encoder and decoder
- Encoder and decoder for short block
- MAC -> PHY configuration using NR FAPI P5 interface
- MAC <-> PHY data interface using FAPI P7 interface for BCH PDU, DCI PDU, PDSCH PDU
- Scheduler procedures for SIB1
- Scheduler procedures for RA
- Contention Free RA procedure
- Contention Based RA procedure
- Msg3 can transfer uplink CCCH, DTCH or DCCH messages
- CBRA can be performed using MAC CE or C-RNTI
- Scheduler procedures for CSI-RS
- MAC downlink scheduler
- phy-test scheduler (fixed allocation and usable also without UE)
- regular scheduler with dynamic allocation
- MCS adaptation from HARQ BLER
- MAC header generation (including timing advance)
- ACK / NACK handling and HARQ procedures for downlink
- MAC uplink scheduler
- phy-test scheduler (fixed allocation)
- regular scheduler with dynamic allocation
- HARQ procedures for uplink
- Scheduler procedures for SRS reception
- MAC procedures to handle CSI measurement report
- evalution of RSRP report
- evaluation of CQI report
- MAC scheduling of SR reception
- Send/Receive operations according to 38.322 Rel.16
- Segmentation and reassembly procedures
- RLC Acknowledged mode supporting PDU retransmissions
- RLC Unacknowledged mode
- DRBs and SRBs establishment/handling and association with RLC entities
- Timers implementation
- Interfaces with PDCP, MAC
- Interfaces with gtp-u (data Tx/Rx over F1-U at the DU)
- Send/Receive operations according to 38.323 Rel.16
- Integrity protection and ciphering procedures
- Sequence number management, SDU dicard and in-order delivery
- Radio bearer establishment/handling and association with PDCP entities
- Interfaces with RRC, RLC
- Interfaces with gtp-u (data Tx/Rx over N3 and F1-U interfaces)
- Send/Receive operations according to 37.324 Rel.15
- Establishment/Handling of SDAP entities.
- Transfer of User Plane Data
- Mapping between a QoS flow and a DRB for both DL and UL
- Marking QoS flow ID in both DL and UL packets
- Reflective QoS flow to DRB mapping for UL SDAP data PDUs
- NR RRC (38.331) Rel 16 messages using new asn1c
- LTE RRC (36.331) also updated to Rel 15
- Generation of CellGroupConfig (for eNB) and MIB
- Generation of system information block 1 (SIB1)
- Generation of system information block 2 (SIB2)
- Application to read configuration file and program gNB RRC
- RRC can configure PDCP, RLC, MAC
- Interface with gtp-u (tunnel creation/handling for S1-U (NSA), N3 (SA) interfaces)
- Integration of RRC messages and procedures supporting UE 5G SA connection
- RRCSetupRequest/RRCSetup/RRCSetupComplete
- RRC Uplink/Downlink Information transfer carrying NAS messages transparently
- RRC Reconfiguration/Reconfiguration complete
- Support for master cell group configuration
- Interface with NGAP for the interactions with the AMF
- Interface with F1AP for CU/DU split deployment option
- Integration of X2AP messages and procedures for the exchanges with the eNB over X2 interface supporting the NSA setup according to 36.423 Rel. 15
- X2 setup with eNB
- Handling of SgNB Addition Request / Addition Request Acknowledge / Reconfiguration Complete
- Integration of NGAP messages and procedures for the exchanges with the AMF over N2 interface according to 38.413 Rel. 15
- NGAP Setup request/response
- NGAP Initial UE message
- NGAP Initial context setup request/response
- NGAP Downlink/Uplink NAS transfer
- NGAP UE context release request/complete
- NGAP UE radio capability info indication
- NGAP PDU session resource setup request/response
- Interface with RRC
- Integration of F1AP messages and procedures for the control plane exchanges between the CU and DU entities according to 38.473 Rel. 16
- F1 Setup request/response
- F1 DL/UL RRC message transfer
- F1 Initial UL RRC message transfer
- F1 UE Context setup request/response
- F1 gNB CU configuration update
- Interface with RRC
- Interface with gtp-u (tunnel creation/handling for F1-U interface)
- New gtp-u implementation supporting both N3 and F1-U interfaces according to 29.281 Rel.15
- Interfaces with RRC, F1AP for tunnel creation
- Interfaces with PDCP and RLC for data send/receive at the CU and DU respectively (F1-U interface)
- Interface with SDAP for data send/receive, capture of GTP-U Optional Header, GTP-U Extension Header and PDU Session Container.
Please, refer here https://openairinterface.org for more information.