Table of Contents

  1. Functional Split Architecture

  2. OpenAirInterface Block Diagram

  3. OpenAirInterface 4G-LTE eNB Feature Set

    1. eNB PHY Layer

    2. eNB MAC Layer

    3. eNB RLC Layer

    4. eNB PDCP Layer

    5. eNB RRC Layer

    6. eNB X2AP

    7. eNB/MCE M2AP

    8. MCE/MME M3AP

  4. OpenAirInterface 4G-LTE UE Feature Set

    1. LTE UE PHY Layer

    2. LTE UE MAC Layer

    3. LTE UE RLC Layer

    4. LTE UE PDCP Layer

    5. LTE UE RRC Layer

  5. OpenAirInterface 5G-NR gNB Feature Set

    1. General Parameters

    2. gNB Physical Layer

    3. gNB Higher Layers

  6. OpenAirInterface 5G-NR UE Feature Set

    1. UE Physical Layer

    2. 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

Functional Split Architecture

OpenAirInterface Block Diagram

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 ; respects vrb_map_UL and vrb_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

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