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OpenAirInterface 5G Training
Florian Kaltenberger & Raymond Knopp
Newcom# Summer School on Waveforms and Network Architectures for the IoT in
5G
15.9.2015, Eurecom, France
OpenAir5GLab 2
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
Outline
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OpenAir5GLab 4
Open-source software-based implementation of 4G LTE (Rel 10)– Spanning the full protocol stack of 3GPP standard
h E-UTRAN (eNB, partial UE) h 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
What is Openairinterface?
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OpenAir5GLab 5
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
Use cases of OAI I
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OpenAir5GLab 6
Non-3GPP setup:– OAI eNB <--> OAI UE
Use cases of OAI II
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OpenAir5GLab 7
Simulation/Emulation (oaisim)– 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)
Use cases of OAI III
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OpenAir5GLab 8
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: https://twiki.eurecom.fr/twiki/bin/view/OpenAirInterface/OpenAirFeatures
OpenAirInterface Features
UEs eNBs
3GPP layers
MAC
RLC
RRC S1-MME
SCTP
X2AP
IP
Ethernet
UDPPDCP
S1-URRC
NAS
MAC
RLC
Linux IP stack
PDCP
Data Plane, IP packetLinux stack
Control Plane
PHYPHY
Ethernet
IP
SCTP
S1-MME
NAS
MME Application
S11 Abstraction S1-U
S+P-GW Application
GTP-U
MME + S+P-GW
eNB Application
IP packets AT commands
UDP
SGiS6a/Diameter
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OpenAir5GLab 9
1. 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
2. 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
3. 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
4. Multi-threaded parallel processing
Key Ingredients (How does OAI work)
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OpenAir5GLab 10
www.openairinterface.org– New website will soon be released
OpenAirInterface SVN Repositories– Core development is available through our SVN repository
http://svn.eurecom.fr/openair4G/trunk– In transition to gitlab:
https://gitlab.eurecom.fr/oai/openairinterface5g
OpenAirInterface TWIKI– A TWIKI site for quick access by partners to our development via a
collaborative HOW-TO– https://twiki.eurecom.fr/twiki/bin/view/OpenAirInterface/WebHome
Mailing list– [email protected] – Anyone can subscribe (send an email to [email protected]
with the subject "subscribe openair4G-devel firstname lastname“)
Collaborative Web Tools
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OpenAir5GLab 12
Ensure a path 4G5G 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)
Next Steps for OAI
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OpenAir5GLab 13
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
The OpenAirInterface Software Alliance
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OpenAir5GLab 14
Make trusted environment– 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
Goals
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OpenAir5GLab 15
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
h 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.
Industrial Users
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OpenAir5GLab 16
“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
Current status
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OpenAir5GLab 18
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)
Hardware Targets for Openair4G
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OpenAir5GLab 19
Express MIMO 2
RF RX (4 way)
RF TX (4 way)
PCI Express (1 or 4 way)
4xLMS6002D RF ASICs250 MHz – 3.8 GHz GPIO for external RF control
Spartan 6 LX150T
12V from ATX power supply
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OpenAir5GLab 20
• 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)
Express MIMO 2
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OpenAir5GLab 21
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
USRP B210
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OpenAir5GLab 22
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 €1,130.00 EUR ~€2,000.00 EUR
Duplexing FDD FDD or TDD
Output power 10dBm 0dBm @ 2.6GHz10dBm @ 700MHz
Noise figure <8dB 10-15dB
Comparison
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OpenAir5GLab 24
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
L1/L2 block
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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OpenAir5GLab 25
…
Master thread architecture (ExpressMIMO)
ExpressMIMO(LEON)
ExpressMIMO(LEON)
PC
Iexp
ress
Master eNB thread
(synchronization)
Master eNB thread
(synchronization)
User SpaceKernel Space
Linux driver(openair_rf.ko)Linux driver
(openair_rf.ko)
OctaveOctaveOctave
API
C API
targets/ARCH/EXMIMO/DRIVER/eurecom
targets/ARCH/EXMIMO/USERSPACE/OCTAVE
targets/ARCH/EXMIMO/USERSPACE/LIB
targ
ets
/AR
CH
/EX
MIM
O/
DE
FS
/pci
e_
inte
rfa
ce.h
Using real-time Linux extension (RTAI, Xenomai, lowlatency kernel)
L1/L2 thread N-1L1/L2 thread N-1
L1/L2 thread 0L1/L2 thread 0
lte-softmodem.c
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OpenAir5GLab 26
Master thread architecture (USRP)
…
USRPUSRPU
SB Master eNB
thread (synchronization)
Master eNB thread
(synchronization)
User Space
UHDUHD
C APItargets/ARCH/USRP/
USERSPACE/LIB
Using real-time Linux extension (RTAI, Xenomai, lowlatency kernel)
L1/L2 thread N-1L1/L2 thread N-1
L1/L2 thread 0L1/L2 thread 0
lte-softmodem.c
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OpenAir5GLab 27
Include vcd plot here
Example of real-time execution
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OpenAir5GLab 29
Experimentally study the impact of 5G waveforms on legacy 4G systems (replicating work in [1])
Lab Scenario and Goal
UE1
eNB1 eNB2
UExUE1Frequency 1
Frequency 2
LTE FDDDL: OFDMA
UL: SC-FDMA
5G TDDDL: OFDMUL: GFDM/
UFMC
Co-channelinterference
reduction
Uses spectrum holes in UL (through sensing or pre-allocated)
Inter-eNBinterference
Kaltenberger, F.; Knopp, R.; Danneberg, M. & Festag, A.Experimental Analysis and Simulative Validation of Dynamic Spectrum Access for Coexistence of 4G and Future 5G SystemsEuropean Conference on Networks and Communications (EuCnC 2015), 2015
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OpenAir5GLab 30
4G system: OpenAirInterface software radio and USRP5G system: emulated using a signal generator
Lab Setup (option 1)
eNB+EPC(OAI) eNB2
UEx
Frequency 1
Frequency 2
LTE FDDDL: OFDMA
UL: SC-FDMA
5G TDDDL: OFDMUL: GFDM/
UFMC
Signal generator
Spectrum Analyzer
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OpenAir5GLab 31
4G system: OpenAirInterface software radio and USRP5G system: emulated using a signal generator
Lab Setup (option 2)
eNB+EPC(OAI) eNB2
5G UE (OAI)
Frequency 1
Frequency 2
LTE FDDDL: OFDMA
UL: SC-FDMA
5G TDDDL: OFDMUL: GFDM/
UFMC
Spectrum Analyzer
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OpenAir5GLab 32
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
Outline
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OpenAir5GLab 33
Lab PC – login = computer name– Password = “linux”
If not already installed in ~/openairinterface5G– Get source from our gitlab server as described in https://
twiki.eurecom.fr/twiki/bin/view/OpenAirInterface/GetSources
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
Useful information
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OpenAir5GLab 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, 36.212, 36.213 3GPP 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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OpenAir5GLab 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
o downlink_frequency=2660000000o mme_ip_address=192.168.12.171o 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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OpenAir5GLab 36
Spectrum Analyzer (UL and DL)– 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
Debug tools
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OpenAir5GLab 37
Transmit secondary waveform in unused UL resources
Make sure the scheduler does not schedule them
Back to our scenario…
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OpenAir5GLab 38
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
The OAI UL scheduler
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OpenAir5GLab 39
OFDM, GFDM: – 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
Secondary waveforms
[1] https://cloudstore.zih.tu-dresden.de/public.php?service=files&t=4073588ff321c26cabf8137c6bc9a61a15/09/2015
OpenAir5GLab 40
For the first experiment we will use pre-generated waveforms– Can be downloaded from
http://www.eurecom.fr/~kaltenbe/5glab– Source can be found at
https://gitlab.eurecom.fr/florian.kaltenberger/5glab
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
First experiment: signal generator
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OpenAir5GLab 41
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 2660000000 -r50 -d -V --ue-scan-carrier --ue-txgain 90 --ue-rxgain 110 --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!
Second experiment: Use OAI UE
15/09/2015
