Table of Contents
Functional Split Architecture
OpenAirInterface Block Diagram
OpenAirInterface 4G-LTE eNB Feature Set
eNB PHY Layer
eNB MAC Layer
eNB RLC Layer
eNB PDCP Layer
eNB RRC Layer
eNB X2AP
eNB/MCE M2AP
MCE/MME M3AP
OpenAirInterface 4G-LTE UE Feature Set
LTE UE PHY Layer
LTE UE MAC Layer
LTE UE RLC Layer
LTE UE PDCP Layer
LTE UE RRC Layer
OpenAirInterface 5G-NR gNB Feature Set
General Parameters
gNB Physical Layer
gNB Higher Layers
OpenAirInterface 5G-NR UE Feature Set
UE Physical Layer
UE Higher Layers
Functional Split Architecture
RCC: Radio-Cloud Center
RAU: Radio-Access Unit
RRU: Remote Radio-Unit
IF4.5 / IF5 : similar to IEEE P1914.1
FAPI (IF2) : specified by Small Cell Forum (open-nFAPI implementation)
IF1 : F1 in 3GPP Release 15
OpenAirInterface Block Diagram
OpenAirInterface 4G LTE eNB Feature Set
eNB PHY Layer
The Physical layer implements 3GPP 36.211, 36.212, 36.213 and provides the following features:
LTE release 8.6 compliant, and implements a subset of release 10
FDD and TDD configurations: 1 (experimental) and 3
Bandwidth: 5, 10, and 20 MHz
Transmission modes: 1, 2 (stable), 3, 4, 5, 6, 7 (experimental)
Max number of antennas: 2
CQI/PMI reporting: aperiodic, feedback mode 3 - 0 and 3 - 1
PRACH preamble format 0
Downlink (DL) channels are supported: PSS, SSS, PBCH, PCFICH, PHICH, PDCCH, PDSCH, PMCH, MPDCCH
Uplink (UL) channels are supported: PRACH, PUSCH, PUCCH (format 1/1a/1b), SRS, DRS
HARQ support (UL and DL)
Highly optimized base band processing (including turbo decoder)
Multi-RRU support: over the air synchro b/ multi RRU in TDD mode
Support for CE-modeA for LTE-M. Limited support for repeatition, single-LTE-M connection, legacy-LTE UE attach is disabled.
Performances
Transmission Mode, Bandwidth |
Expected Throughput |
Measured Throughput |
Measurement Conditions |
---|---|---|---|
FDD DL: 5 MHz, 25 PRBS/ MCS 28 |
16 - 17 Mbit/s |
TM1: 17.0 Mbits/s |
COTS-UE Cat 4 (150/50 Mbps) |
FDD DL: 10 MHz, 50 PRBS/ MCS 28 |
34 - 35 Mbit/s |
TM1: 34.0 Mbits/s |
COTS-UE Cat 4 (150/50 Mbps) |
FDD DL: 20 MHz, 100 PRBS/ MCS 28 |
70 Mbit/s |
TM1: 69.9 Mbits/s |
COTS-UE Cat 4 (150/50 Mbps) |
FDD UL: 5 MHz, 25 PRBS/ MCS 20 |
9 Mbit/s |
TM1: 8.28 Mbits/s |
COTS-UE Cat 4 (150/50 Mbps) |
FDD UL: 10 MHz, 50 PRBS/ MCS 20 |
17 Mbit/s |
TM1: 18.3 Mbits/s |
COTS-UE Cat 4 (150/50 Mbps) |
FDD UL: 20 MHz, 100 PRBS/ MCS 20 |
35 Mbit/s |
TM1: 18.6 Mbits/s |
COTS-UE Cat 4 (150/50 Mbps) |
TDD DL: 5 MHz, 25 PRBS/ MCS XX |
6.5 Mbit/s |
TM1: 6.71 Mbits/s |
COTS-UE Cat 4 (150/50 Mbps) |
TDD DL: 10 MHz, 50 PRBS/ MCS XX |
13.5 Mbit/s |
TM1: 13.6 Mbits/s |
COTS-UE Cat 4 (150/50 Mbps) |
TDD DL: 20 MHz, 100 PRBS/ MCS XX |
28.0 Mbit/s |
TM1: 27.2 Mbits/s |
COTS-UE Cat 4 (150/50 Mbps) |
TDD UL: 5 MHz, 25 PRBS/ MCS XX |
2.0 Mbit/s |
TM1: 3.31 Mbits/s |
COTS-UE Cat 4 (150/50 Mbps) |
TDD UL: 10 MHz, 50 PRBS/ MCS XX |
2.0 Mbit/s |
TM1: 7.25 Mbits/s |
COTS-UE Cat 4 (150/50 Mbps) |
TDD UL: 20 MHz, 100 PRBS/ MCS XX |
3.0 Mbit/s |
TM1: 4.21 Mbits/s |
COTS-UE Cat 4 (150/50 Mbps) |
Number of supported UEs
16 by default
up to 256 when compiling with dedicated compile flag
was tested with 40 COTS-UE
eNB MAC Layer
The MAC layer implements a subset of the 3GPP 36.321 release v8.6 in support of BCH, DLSCH, RACH, and ULSCH channels.
RRC interface for CCCH, DCCH, and DTCH
Proportional fair scheduler (round robin scheduler soon), with the following improvements:
Up to 30 users tested in the L2 simulator, CCE allocation in the preprocessor ; the scheduler was also simplified and made more modular
Adaptative UL-HARQ
Remove out-of-sync UEs
No use of the
first_rb
in the UL scheduler ; respectsvrb_map_UL
andvrb_map
in the DL
DCI generation
HARQ Support
RA procedures and RNTI management
RLC interface (AM, UM)
UL power control
Link adaptation
Connected DRX (CDRX) support for FDD LTE UE. Compatible with R13 from 3GPP. Support for Cat-M1 UE comming soon.
eNB RLC Layer
The RLC layer implements a full specification of the 3GPP 36.322 release v9.3.
RLC TM (mainly used for BCCH and CCCH)
Neither segment nor concatenate RLC SDUs
Do not include a RLC header in the RLC PDU
Delivery of received RLC PDUs to upper layers
RLC UM (mainly used for DTCH)
Segment or concatenate RLC SDUs according to the TB size selected by MAC
Include a RLC header in the RLC PDU
Duplication detection
PDU reordering and reassembly
RLC AM, compatible with 9.3
Segmentation, re-segmentation, concatenation, and reassembly
Padding
Data transfer to the user
RLC PDU retransmission in support of error control and correction
Generation of data/control PDUs
eNB PDCP Layer
The current PDCP layer is header compliant with 3GPP 36.323 Rel 10.1.0 and implements the following functions:
User and control data transfer
Sequence number management
RB association with PDCP entity
PDCP entity association with one or two RLC entities
Integrity check and encryption using the AES and Snow3G algorithms
eNB RRC Layer
The RRC layer is based on 3GPP 36.331 v15.6 and implements the following functions:
System Information broadcast (SIB 1, 2, 3, and 13)
SIB1: Up to 6 PLMN IDs broadcast
RRC connection establishment
RRC connection reconfiguration (addition and removal of radio bearers, connection release)
RRC connection release
RRC connection re-establishment
Inter-frequency measurement collection and reporting (experimental)
eMBMS for multicast and broadcast (experimental)
Handover (experimental)
Paging (soon)
RRC inactivity timer (release of UE after a period of data inactivity)
eNB X2AP
The X2AP layer is based on 3GPP 36.423 v14.6.0 and implements the following functions:
X2 Setup Request
X2 Setup Response
X2 Setup Failure
Handover Request
Handover Request Acknowledge
UE Context Release
X2 timers (t_reloc_prep, tx2_reloc_overall)
Handover Cancel
X2-U interface implemented
EN-DC is implemented
X2AP : Handling of SgNB Addition Request / Addition Request Acknowledge / Reconfiguration Complete
RRC : Handling of RRC Connection Reconfiguration with 5G cell info, configuration of 5G-NR measurements
S1AP : Handling of E-RAB Modification Indication / Confirmation
eNB/MCE M2AP
The M2AP layer is based on 3GPP 36.443 v14.0.1:
M2 Setup Request
M2 Setup Response
M2 Setup Failure
M2 Scheduling Information
M2 Scheduling Information Response
M2 Session Start Request
M2 Session Start Response
MCE/MME M3AP
The M3AP layer is based on 3GPP 36.444 v14.0.1:
M3 Setup Request
M3 Setup Response
M3 Setup Failure
M3 Session Start Request
M3 Session Start Response
OpenAirInterface 4G LTE UE Feature Set
LTE UE PHY Layer
The Physical layer implements 3GPP 36.211, 36.212, 36.213 and provides the following features:
LTE release 8.6 compliant, and implements a subset of release 10
FDD and TDD configurations: 1 (experimental) and 3
Bandwidth: 5, 10, and 20 MHz
Transmission modes: 1, 2 (stable)
Max number of antennas: 2
CQI/PMI reporting: aperiodic, feedback mode 3 - 0 and 3 - 1
PRACH preamble format 0
All downlink (DL) channels are supported: PSS, SSS, PBCH, PCFICH, PHICH, PDCCH, PDSCH, PMCH
All uplink (UL) channels are supported: PRACH, PUSCH, PUCCH (format 1/1a/1b), SRS, DRS
LTE MBMS-dedicated cell (feMBMS) procedures subset for LTE release 14 (experimental)
LTE non-MBSFN subframe (feMBMS) Carrier Adquistion Subframe-CAS procedures (PSS/SSS/PBCH/PDSH) (experimental)
LTE MBSFN MBSFN subframe channel (feMBMS): PMCH (CS@1.25KHz) (channel estimation for 25MHz bandwidth) (experimental)
LTE UE MAC Layer
The MAC layer implements a subset of the 3GPP 36.321 release v8.6 in support of BCH, DLSCH, RACH, and ULSCH channels.
RRC interface for CCCH, DCCH, and DTCH
HARQ Support
RA procedures and RNTI management
RLC interface (AM, UM)
UL power control
Link adaptation
MBMS-dedicated cell (feMBMS) RRC interface for BCCH
eMBMS and MBMS-dedicated cell (feMBMS) RRC interface for MCCH, MTCH
LTE UE RLC Layer
The RLC layer implements a full specification of the 3GPP 36.322 release v9.3.
LTE UE PDCP Layer
The current PDCP layer is header compliant with 3GPP 36.323 Rel 10.1.0.
LTE UE RRC Layer
The RRC layer is based on 3GPP 36.331 v14.3.0 and implements the following functions:
System Information decoding
RRC connection establishment
MBMS-dedicated cell (feMBMS) SI-MBMS/SIB1-MBMS management
LTE UE NAS Layer
The NAS layer is based on 3GPP 24.301 and implements the following functions:
EMM attach/detach, authentication, tracking area update, and more
ESM default/dedicated bearer, PDN connectivity, and more
OpenAirInterface 5G-NR Feature Set
General Parameters
The following features are valid for the gNB and the 5G-NR UE.
Static TDD,
Normal CP
30 kHz subcarrier spacing
Bandwidths up to 80MHz (217 Physical Resource Blocks)
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
gNB PHY Layer
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 for SIB1 (including generation of DCI, polar encoding, scrambling, modulation, RB mapping, etc)
common search space configured by MIB
user-specific search space configured by RRC
DCI formats: 00, 10 (01 and 11 under integration)
Generation of NR-PDSCH (including Segmentation, LDPC encoding, rate matching, scrambling, modulation, RB mapping, etc).
Single symbol DMRS, DMRS-TypeA-Position Pos2, DMRS configuration type 1
PDSCH mapping type A
NR-CSI Generation of sequence at PHY (under integration)
NR-PUSCH (including Segmentation, LDPC encoding, rate matching, scrambling, modulation, RB mapping, etc).
NR-PUCCH
Format 0 (2 bits, mainly for ACK/NACK)
Format 2 (up to 64 bits, mainly for CSI feedback)
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
gNB Higher Layers
gNB RRC
NR RRC (38.331) Rel 15 messages using new asn1c
LTE RRC (36.331) also updated to Rel 15
Generation of CellGroupConfig (for eNB) and MIB
Application to read configuration file and program gNB RRC
RRC can configure PDCP, RLC, MAC
gNB X2AP
X2 setup with eNB
Handling of SgNB Addition Request / Addition Request Acknowledge / Reconfiguration Complete
gNB MAC
MAC -> PHY configuration using NR FAPI P5 interface
MAC <-> PHY data interface using FAPI P7 interface for BCH PDU, DCI PDU, PDSCH PDU
Scheduler for RA procedreat gNB
MAC downlink scheduler (fixed allocations)
MAC header generation (including timing advance)
ACK / NACK handling and HARQ procedures for downlink
As of May 2020 only DL was validated with COTS phone ; UL in progress, validated with OAI UE in noS1 mode
OpenAirInterface 5G-NR UE Feature Set
as of May 2020 only supporting “noS1” mode (DL):
Creates TUN interface to PDCP to inject and receive user-place traffic
Will only work with OAI gNB configured in the same mode
UE PHY Layer
Initial synchronization
Time tracking based on PBCH DMRS
Time tracking based on PBCH DMRS
Frequency offset estimation
PBCH RX
PDCCH RX
PDSCH RX, including a first version of dual stream receiver for PDSCH
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 for SIB1 (including generation of DCI, polar encoding, scrambling, modulation, RB mapping, etc)
common search space configured by MIB
user-specific search space configured by RRC
DCI formats: 00, 10 (01 and 11 under integration)
Generation of NR-PDSCH (including Segmentation, LDPC encoding, rate matching, scrambling, modulation, RB mapping, etc).
Single symbol DMRS, DMRS-TypeA-Position Pos2, DMRS configuration type 1
PDSCH mapping type A
NR-CSI Generation of sequence at PHY (under integration)
NR-PUSCH (including Segmentation, LDPC encoding, rate matching, scrambling, modulation, RB mapping, etc).
NR-PUCCH
Format 0 (2 bits, mainly for ACK/NACK)
Format 2 (up to 64 bits, mainly for CSI feedback)
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
UE Higher Layers
gNB MAC
Initial sync and MIB detection
MAC -> PHY configuration of PHY via UE FAPI P5 interface
Basic MAC to control PHY via UE FAPI P7 interface
Random access procedure
RLC
PDCP