1. OpenAirInterface 5G Training
Florian Kaltenberger & Raymond Knopp
Newcom# Summer School on Waveforms and Network Architectures for the IoT in 5G
, Eurecom, France

2. Outline OpenAirInterface Overview
Features
Use cases
The OpenAirInterface 5G Software Alliance
OpenAirInterface Software Architecture
Signal acquisition and transmission
Functional blocks and Interfaces
Some example procedures and data flows
Lab sessions
Scenario
Installation
Run eNB, connect UE, run iperf to measure TP
Analyze the output of logs, scope, and VCD plots
Analyze the spectrum usage using spectrum analyzer
Modify scheduler
Transmit secondary waveform
Measure TP again
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OpenAir5GLab

3. OpenAirInterface Overview
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4. What is Openairinterface?
Open-source software-based implementation of 4G LTE (Rel 10)
Spanning the full protocol stack of 3GPP standard
E-UTRAN (eNB, partial UE)
EPC (MME, S+P-GW, HSS)
Realtime RF and scalable emulation platforms
Targets EURECOM and National Instruments HW platforms (others in development)
Objectives
Bring academia closer to complex real-world systems
Open-source tools to ensure a common R&D and prototyping framework for rapid proof-of-concept designs
Other use cases
Interoperability with 3rd party components (UE, eNB, EPC)
Matlab/Octave tools for non real-time experimentation
Real-time channel sounding (EMOS)
802.11p Modem
Unitary simulations
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5. Use cases of OAI I Classical 3GPP setup:
OAI EPC + OAI eNB <--> COTS UE
Commercial/3rd party EPC + OAI eNB <-->COTS UE
OAI EPC + Commercial/3rd party eNB <--> COTS UE
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6. Use cases of OAI II Non-3GPP setup: OAI eNB <--> OAI UE
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7. Use cases of OAI III Simulation/Emulation (oaisim) Unitary simulators
OAI eNB <--> OAI UE
OAI EPC + OAI eNB <--> OAI UE
Comercial/3rd party EPC + OAI eNB <--> OAI UE
Unitary simulators
DLSCH simulator dlsim
ULSCH simulator ulsim
PUCCH simulator pucchsim
PRACH simulator prachsim
PDCCH simulator pdcchsim
PBCH simulator pbchsim
eMBMS simulator mbmssim
Other uses
EMOS (real-time channel sounding)
octave (simple experimentation)
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8. OpenAirInterface Features
Implements 4G LTE Rel10 Access Stratum (eNB & UE) and EPC (MME, S+P-GW, HSS)
All the stack (incl. PHY) runs entirely on a PC in real-time operating system (RTAI, Xenomai, low-latency kernel)
Works with ExpressMIMO (Eurecom) and USRP (Ettus/National Instruments)
More detailed feature list here:
Add sgi
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9. Key Ingredients (How does OAI work)
Real-time extensions to Linux OS
Today we rely on the lowlatency kernel provided by Ubuntu (since Ubuntu 14.04)
In earlier Ubuntu versions RTAI was used
Real-time data acquisition to/from PC
ExpressMIMO uses DMA to transfer signals in and out of PC memory without hogging CPU -> very efficient
USRP transfers data over USB and therefore requires extra CPU time for (de-)packetization of signals
Highly optimized DSP routines running on Intel GPP
Exploiting vector processing (SIMD)
64-bit MMX  128-bit SSE2/3/4  256-bit AVX2
OAI features fastest FFT and Turbo decoder of its kind
Multi-threaded parallel processing
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10. Collaborative Web Tools
New website will soon be released
OpenAirInterface SVN Repositories
Core development is available through our SVN repository
In transition to gitlab:
OpenAirInterface TWIKI
A TWIKI site for quick access by partners to our development via a collaborative HOW-TO
Mailing list
Anyone can subscribe (send an to with the subject "subscribe openair4G-devel firstname lastname“)
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11. The OpenAirInterface 5g Software Alliance
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12. Next Steps for OAI Ensure a path 4G5G through open-source policy
Work with new carrier candidates now, short packet low-latency carriers, contention-based access
VRAN, MEC architectures
Rapidly-deployable EPC/eNB (with LTE or other backhaul)
Become a reference implementation of Rel 13/14  5G
Serious contributors from outside Eurecom
“ready to use” for anybody on commodity hardware (PCs + National Instruments)
More global adoption for innovation and research (Vendor labs, University Labs, etc.)  common tool between industrial and academic research
Business adoption in test market (Keysight)
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13. The OpenAirInterface Software Alliance
Cellular systems are expected to converge from a proprietary and expensive HW/SW platforms towards an open SW platforms over commodity HW
Happened already for cloud service
Happened already for handsets
Happened already for 2G
To foster the innovation in wireless world, there is a need for an open cellular ecosystem for 4G towards 5G
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14. Goals Make trusted environment Increase quality & simplify access
Contributors and users need to secure themselves
Clear open source rules
Any individual person or non-profit organization can become a member for free
Membership conditions for companies
Increase quality & simplify access
Simple and well described binary build procedures for all the LTE components
Friendly to various RF systems (RRH, SmallCell, etc.)
Anybody can build a fully open-source 4G network comprising a couple of eNBs + EPC for less than 10K€ and 1 human week of effort
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15. Industrial Users
Alcatel-Lucent Bell Labs (Paris, New Jersey, Stuttgart)
Running OAI systems (OAI eNB interconnected with ALU in-house EPC development)
Contributions to core access-stratum software
Integration with in-house CPRI-based solutions and commercial RRH
VRAN Architectures
5G-waveforms (soon)
ChinaMobile CRAN Project (Beijing)
Building demonstrator with OAI software for CloudRAN proof-of-concept, live real-time deployment, 20 MHz TD-LTE
OAI software on commodity computing equipmen t (IBM x86 servers) + commercial remote radio-heads
Keysight China (ex Agilent): interop testing for China Mobile CRAN
IBM China : parallelization architectures for China Mobile CRAN
National Instruments / Ettus Research
Support for porting OAI software to Ettus USRP platforms (B210, X310)
Roadmap for integration on PXIe high-end industrial platforms
Air-Lynx (SME, Paris)
Rapidly (and less rapidly)-deployable eNB/EPC
Currently evaluating EURECOM HW and OAI eNB/EPC/UE for public-safety applications
Software has been analyzed independently by Intel for maturity in CloudRAN context.
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16. Current status “Fonds de dotation” officially created
Ongoing discussions with first round of strategic members
First official board meeting expected in autumn
License switch from GPLv3 to a “modified Apache” licensed ongoing
Will allow non-contaminating interfacing with proprietary HW and SW
Will allow contributions from industry that are patented
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17. OpenAirInterface Hardware and Software
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18. Hardware Targets for Openair4G
ExpressMIMO2
Eurecom board, designed and maintained by EURECOM
1.5/5/10/20 MHz, FDD/TDD
4 channels (4x4 MIMO or 4 SISO Component Carriers)
Total aggregate bandwidth: full duplex 64Msps (Corresponds to 4x5MHz, 2x10MHz, or 1x 20MHz full duplex)
USRP B210/X300
Commercial Ettus/National Instruments boards
Platforms under development
PXIe (National Instruments)
Nutaq
Novena + Myriad RF (Lime Microsystems)
Blade RF (nuand)
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19. Express MIMO 2 RF RX (4 way) RF TX (4 way) PCI Express (1 or 4 way)
Spartan 6 LX150T
12V from ATX power supply
4xLMS6002D RF ASICs
250 MHz – 3.8 GHz
GPIO for external RF control
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20. Express MIMO 2
Integrated baseband/RF PCI Express board for x86-based software defined radio
Xilinx Spartan 6 FPGA
4 RF chains based on LIME LMS6002D Semiconductor zero-IF RF chipsets
Carrier frequencies: 300 MHz – 3.8 GHz
Bandwidth: 20MHz
FDD or TDD operation
~10 dBm output power
LTE RF compliance (UE, small-cell eNB)
Status:
more than 60 cards currently fabricated
used by many research institutes (academic and industrial)
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21. USRP B210 Designed by ETTUS (now part of NI)
Analog Devices AD9361 RFIC Dual Channel Transceiver (70 MHz - 6GHz)
Full duplex, MIMO (2 Tx & 2 Rx) operation with up to 56 MHz of real-time bandwidth (61.44MS/s quadrature)
Slightly less in our experiments
Data acquisition over USB3
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22. Comparison USRP B210 ExpressMIMO2 Data acquisition
USB: requires extra processing power
PCI using DMA: no overhead for CPU
MIMO and bandwidth capabilities
2x1 MIMO 20MHz or 2x2 MIMO 10MHz
4x4 MIMO 5 MHz, 2x2 MIMO 10Mhz, SISO 20MHz
RF performance
More sophisticated RF cleanup
Simple RF calibration
Frequency range
70MHz – 6GHz
300 MHz – 3.8GHz
Price
€1, EUR
~€2, EUR
Duplexing
FDD
FDD or TDD
Output power
10dBm
2.6GHz 700MHz
Noise figure
<8dB
10-15dB
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23. OAI software architecture
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24. L1/L2 block OAI follows 3GPP LTE architecture
Good knowledge of LTE is prerequisite to understand OAI
Each block has its own data structure and functions
Interfaces between most blocks are implemented as function calls
Following interfaces are implemented using the Intertask Interface (ITTI) framework
RRC ↔ PDCP,
RRC ↔ S1AP,
PDCP ↔ S1AP
L1/L2 thread instantiated multiple times
For each TX/RX subframe
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25. Master thread architecture (ExpressMIMO)
(LEON) …
lte-softmodem.c
PCIexpress
L1/L2 thread 0
Kernel Space
targets/ARCH/EXMIMO/ DEFS/pcie_interface.h
User Space
Master eNB thread (synchronization)
L1/L2 thread N-1
C API
Using real-time Linux extension (RTAI, Xenomai, lowlatency kernel)
Linux driver
(openair_rf.ko)
targets/ARCH/EXMIMO/ USERSPACE/LIB
targets/ARCH/EXMIMO/DRIVER/eurecom
Octave
API
Octave
targets/ARCH/EXMIMO/USERSPACE/OCTAVE
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26. Master thread architecture (USRP)
User Space …
lte-softmodem.c
USB
L1/L2 thread 0
Master eNB thread (synchronization)
L1/L2 thread N-1
C API
Using real-time Linux extension (RTAI, Xenomai, lowlatency kernel)
UHD
targets/ARCH/USRP/ USERSPACE/LIB
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27. Example of real-time execution
Include vcd plot here
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28. 4G/5G co-existance experiments
Lab session
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29. Lab Scenario and Goal
Experimentally study the impact of 5G waveforms on legacy 4G systems (replicating work in [1])
Inter-eNB interference
eNB1
eNB2
5G TDD DL: OFDM
UL: GFDM/
UFMC
LTE FDD
DL: OFDMA
UL: SC-FDMA
UE1
UE1
Co-channel interference reduction
UEx
Uses spectrum holes in UL (through sensing or pre-allocated)
Frequency 1
Frequency 2
Kaltenberger, F.; Knopp, R.; Danneberg, M. & Festag, A. Experimental Analysis and Simulative Validation of Dynamic Spectrum Access for Coexistence of 4G and Future 5G Systems European Conference on Networks and Communications (EuCnC 2015), 2015
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30. Lab Setup (option 1)
4G system: OpenAirInterface software radio and USRP 5G system: emulated using a signal generator
eNB+EPC
(OAI)
eNB2
Spectrum Analyzer
5G TDD DL: OFDM
UL: GFDM/
UFMC
LTE FDD
DL: OFDMA
UL: SC-FDMA
UEx
Signal generator
Frequency 1
Frequency 2
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31. Lab Setup (option 2)
4G system: OpenAirInterface software radio and USRP 5G system: emulated using a signal generator
eNB+EPC
(OAI)
eNB2
Spectrum Analyzer
5G TDD DL: OFDM
UL: GFDM/
UFMC
LTE FDD
DL: OFDMA
UL: SC-FDMA
5G UE (OAI)
Frequency 1
Frequency 2
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OpenAir5GLab

32. Outline OpenAirInterface Overview
Features
Use cases
The OpenAirInterface 5G Software Alliance
OpenAirInterface Software Architecture
Signal acquisition and transmission
Functional blocks and Interfaces
Some example procedures and data flows
Lab sessions
Scenario, setup and goals
Installation of OpenAirInterface
Run eNB, connect UE, run iperf to measure throughput
Analyze the output of logs, scope, and VCD plots
Analyze the spectrum usage using spectrum analyzer
Analyze and modify eNB scheduler
Generate and transmit secondary waveform
Measure impact of secondary waveform on throughput of primary system
15/09/2015
OpenAir5GLab

33. Useful information Lab PC
login = computer name
Password = “linux”
If not already installed in ~/openairinterface5G
Get source from our gitlab server as described in
Switch to branch and update
cd openairinterface5g
git checkout feature-23-ufmc
git pull
This branch is the same as the master but with some additional (but unfinished) features for UFMC
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34. OpenAirInterface5G directories
cmake_targets
New directory for building all the targets
Contains “mother” build_oai script
targets
Hardware specific code (drivers, tools, etc)
lte-softmodem, oaisim
openair1
Basic DSP routines for implementing subset of LTE specifications under x86 (36.211, , GPP specifications)
Channel simulation, sounding and PHY abstraction software,
openair2
MAC/RLC/PDCP/RRC
openair3
Pretty much unused
openair-cn
EPC related parts of the eNB: S1AP, X2AP
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35. Compiling and running Initialize environment variables
cd openairinterface5g
source oaienv
Compile lte-softmodem
cd cmake_targets
./build_oai –w USRP –-eNB –x -V
This creates
~/openairinterface5g/targets/bin/lte-softmodem.Rel10
Configuration files
targets/PROJECTS/GENERIC-LTE-EPC/CONF/
Open enb.band7.tm1.50PRB.usrpb210.conf and change
downlink_frequency=
mme_ip_address=
S1-MME and S1-U interfaces should be the ones of your PC
Run using
sudo ./lte-softmodem.Rel10 –O <file.conf> -d –V
Start the UE!
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36. Debug tools Spectrum Analyzer (UL and DL) Logs PHY scope Stats window
Shows RF performance and signal integrity
Logs
Verbosity can be adjusted in config file
Shows L2/L3 events
PHY scope
signals in time and frequency domain
Constellation plots of PUSCH, PUCCH
Stats window
eNB measurements (noise, signal power, etc)
UE feedback (CQI, etc.)
UL and DL HARQ statistics
VCD file
Analyze real-time behavior
gtkwave -a ~/openairinterface5g/targets/RT/USER/eNB_usrp.gtk
Wireshark
To analyze messages over S1 interface
Can also analyze MAC, RLC, PDCP, RRC if enables (see twiki for details)
Iperf/speedtest
Shows throughout for UDP and IP
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37. Back to our scenario…
Transmit secondary waveform in unused UL resources
Make sure the scheduler does not schedule them
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38. The OAI UL scheduler
Check function schedule_ulsch_rnti in file openair2/LAYER2/MAC/eNB_scheduler_ulsch.c
Scheduler will always start scheduling at RB1 (RB0 and RB24 are reserved for PUCCH)
Scheduler can only schedule N = 2a3b5c RBs per UE
 for 5MHz: Nmax = 20; for 10MHz: Nmax = 48
 for 5MHz, RBs 21,22,23 are free as long as there is only 1 UE connected
 for 10MHz, we need to reduce Nmax to 45 to keep RBs 46,47,48 free
 modify line 821 of eNB_scheduler_ulsch.c accordingly
 use this space for secondary waveform
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39. Secondary waveforms OFDM, GFDM: SCFDMA, UFMC:
may be generated with GFDMlib provided by TU-Dresden [1]
SCFDMA, UFMC:
may be generated with OpenAirInterface, branch feature-23-ufmc
UFMC is still in a very early development and only signal generation will work
Signals can be generated either offline with ufmcsim or in real-time with lte-softmodem
Folder also contains tool to convert to file for signal generator (mat2wv)
Build ufmcsim using ./build_oai --phy_simulators
Run using ./ufmcsim -a -s 12 -n 1 -m 9 -B 50 -r 3 -f 0 -u
[1]
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40. First experiment: signal generator
For the first experiment we will use pre-generated waveforms
Can be downloaded from
Source can be found at
Load the waveforms in the signal generator
Run a speedtest (or similar) on the UE
Adjust signal power until degradation can be seen
Take screenshots of the UL spectrum
Measure throughput as a function of TX power of secondary waveform
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41. Second experiment: Use OAI UE
Compile lte-softmodem without S1 interface
full integration with UE NAS not yet available
./build_oai –w USRP --eNB –x -V --noS1
This creates
targets/bin/lte-softmodem-nos1.Rel10
UE is also launched using lte-softmodem
. init_nas_nos1 UE
./lte-softmodem-nos1-Rel10 –U –C r50 -d -V --ue-scan-carrier --ue-txgain ue-rxgain no-L2-connect
This will make the UE synchronize to the eNB but UE will not try to connect
Add option -u to make the UE transmit UFMC signal
Repeat the same procedure as in experiment 1!
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