UFMC - 5GNow

5G Waveform Approaches In Highly
Asynchronous Settings
Presenter: Gerhard Wunder, gerhard.wunder@hhi.fraunhofer.de
EuCNC Workshop “Enablers on the road to 5G”
June 23rd, 2014
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What is 5GNOW?
5GNOW (5th Generation Non-Orthogonal Waveforms for Asynchronous
Signalling) is an European collaborative research project supported by
the European Commission within FP7 ICT Call 8.
Who is in the consortium?

Fraunhofer HHI (coordinator), Germany, Dr. Gerhard Wunder
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Alcatel Lucent (technical coord.), Germany, Thorsten Wild
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Technische Universität Dresden, Germany, Prof. Gerhard Fettweis
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CEA-LETI, France, Dr. Dimitri Ktenas
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IS-Wireless, Poland, Dr. Slawomir Pietrzyk
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National Instruments, Hungary, Dr. Bertalan Eged
www.5gnow.eu, LinkedIn group
Vision:
• 5GNOW is the physical layer evolution of mobile communication network
technology such as LTE-Advanced towards emerging application challenges.
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(1) 5GNOW Application Challenges
(2) 5GNOW Frame Structure
Outline
(3) 5GNOW Waveform Approaches
(4) Conclusions
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Gigabit Wireless Connectivity

Examples: 3D video streaming, large crowd gatherings
2005
2013
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4
Internet of Things (IoT)
■ Connecting the things of every day life, scalable connectivity for
billions of devices
Cost below 10$
Battery (10 years)
Coverage (deep indoor)
„Plug&secure“,
human in the loop
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Tactile Internet (TI)
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Real-time cyber-physical control applications
100ms
10ms
100 µs latency on physical layer!
1ms
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Fragmented Spectrum
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Spectrum paradox: spectrum scarce and expensive but
underutilized!
EC Digital Agenda forces the systems to deal with fragmented
spectrum and white spaces communication (PAPR, 100x better
localization)
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Application Challenges
Wireless Access:
•
•
•
•
flexible
scalable
fast
robust
• reliable
• efficient (energy, spectrum)
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Frame Structure
Concept
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Unified Frame Structure
Layer
Type III and Type IV
Target for 5G integrated air interface:
Efficiently combine various
types of service and
performance classes
within a radio frame
(from small packet service
to high rate ‘bit-pipe’)
Time
Type II
Type I
Frequency
Traffic Type
Synch?
Access Type
Properties
I
closed-loop
scheduled
classical high volume data services
II
open-loop
scheduled
HetNet and/or cell edge multi-layered
high data traffic
III
open-loop
sporadic, contention-based
few bits, supporting low latency,
e.g. smartphone apps
IV
open-loop/none*
contention-based
energy-efficient, high latency, few bits
*: none for maximal energy savings at Tx, open-loop for reduced complexity at Rx
Requirements
Some arguments against OFDM:
• Flexibility: Cyclic prefixes reduce spectral efficiency
and prohibit flexible handling of frame formats
• Scalable: Spectral localization is too bad, e.g. in
narrowband setting up to 4-6 subcarrier gain by
different waveforms
• Robust and Reliable: OFDM is very sensitive both in
time and frequency domain due to FFT
• Fast: Very difficult to support short symbols with given
channel delay spread
• Efficient (energy, spectrum): OFDM is not robust
under incomplete channel state information
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Asynchronous Reference
Scenario
Main observation: OFDM fails in highly asynchronous access
scenarios, e.g. for massive MTC communication.
-18
MSE [dB]
-20
-22
-24
-26
-28
-30
-0.5
UFMC, no CFO
UFMC, 5% CFO
UFMC, 10% CFO
CPOFDM, no CFO
CPOFDM, 5% CFO
CPOFDM, 10% CFO
-0.4
-0.3
-0.2
0
0.1
-0.1
relative delay
0.2
0.3
0.4
0.5
G. Wunder, P. Jung, M. Kasparick, T. Wild, F. Schaich, S. ten Brink, Y. Chen, I. Gaspar, N. Michailow, A. Festtag, G. Fettweis, N.
Cassiau, D. Ktenas, M. Dryjanski, S. Pietrzyk, B. Eged, P. Vago, and F. Wiedmann, “5GNOW: Non-Orthogonal, Asynchronous
Waveforms for Future Mobile Applications“, IEEE Communications Magazine, 5G Special Issue, Feb. 2014
Outside CP:
New waveforms really make a difference!
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Waveform
Concepts
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Filter Bank Multicarrier (FBMC)
Features:
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Non-orthogonal multicarrier modulation (in complex domain)  OQAM
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Prototype filter optimized for time and frequency localization trade-off
(PHYDYAS, K=4 optimized for ACLR)
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Non-adjacent subcarriers are almost perfectly separated
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Spectral efficiency improved as no cyclic prefix is required
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Efficient implementation with IFFT/FFT
Overlapping of time symbols: ISI
solved by OQAM modulation
FBMC transmitter with filtering in the frequency domain
Nicolas Cassiau, Dimitri Kténas, Jean Baptiste Doré, “Time and frequency synchronization for CoMP with FBMC”, Tenth International Symposium on Wireless
Communication Systems (ISWCS’13), Ilmenau, Germany, August, 2013
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High performance receiver for frequencyspreading FBMC
A receiver suited for asynchronous uplink multiuser access and fragmented spectrum
operation
One unique (larger) FFT for all
users
Relaxed synchro requirements
prototype filter
All treatments are realized in the frequency domain
BEFORE filtering by prototype filter
one-tap
equalizer
Low complexity CFO
Three interpolation filters (left,
correction
middle and right)
(see on next slide)
Performance of FBMC Multiple Access
with Relaxed Synchronization
•
•
Due to fair frequency localization e.g. with fragmented spectrum, only the carriers located at the edges
of the active spectrum are affected by interference (OFDM: interference is spread over all the active
carriers)
FBMC waveforms permit a simple way of sharing resources between cell-edge users without strict
synchronization between users due to the low level of uplink interference generated by the built-in
waveform filter.
Performance of FBMC Multiple Access
with Relaxed Synchronization
•
•
•
In case of QPSK, without guard carrier,
the capacity is close to synchronous
transmission and the level of
interference is much lower than the
required SNR to allow the decoding of
QPSK.
For 16-QAM modulation, FBMC gives
a significantly better capacity,
particularly in the range of [10-20]dB of
SNR. Due to the better frequency
localization, only the carriers located at
the border of the user spectrum are
affected by interference.
For 64-QAM, the FBMC waveform
clearly outperforms the OFDM
waveform. Interference dominates the
SINR for OFDM waveform and
consequently for a given capacity of 5
bits/s/carrier, the SNR loss is of around
5dB.
Universal Filtered Multicarrier (UFMC)
s1k
s2k
sBk
IDFT
spreader V1k
+ P/S
Filter F1k
with
length L
x1k
IDFT spreader
V2k
+ P/S
Filter F2k
with
length L
x2k
IDFT
spreader VBk
+ P/S
Filter FBk
with
length L
xBk
Frequency
domain
symbol
processing
(e.g. per
subcarrier
equalization)
+
•
Generalization of Filtered OFDM and FBMC (FMT)
•
UFMC complexity similar to OFDM
•
Huge knowledge base of OFDM processing can be re-applied
to UFMC
xk
Baseband
to RF
channel
Time
domain preprocessing
(e.g.
windowing)
+ S/P
2N pointFFT
0
0
noise n
+
other
users
RF to
Baseband
zeropadding
0
V. Vakilian, T. Wild, F. Schaich, S.t. Brink, J.-F. Frigon, "Universal-Filtered Multi-Carrier Technique for Wireless Systems Beyond LTE", IEEE
Globecom'13, Atlanta, December 2013
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Uplink CoMP: UFMC vs OFDM
• UFMC adds increased robustness in CoMP against timefrequency misalignments
•
CFO is estimated and
compensated.
•
CFO estimation error Δε
Parameters
UFMC
•
CFO 10% of subcarrier
spacing
•
QPSK
•
FFT size 128
•
12 subc. per PRB
•
6 PRBs allocated
•
Filter length / CP length
16
•
UFMC: DolphChebychev filters with
120 dB att.
•
Frequency-selective
fading channel (16 taps)
OFDM
Generalized Frequency Division
Multiplexing (GFDM)
Waveform Properties
Multidimensional block
structure with cyclic prefix:
Circular sub-carrier pulse shape:
Overlapping (non-orthogonal) sub-carriers:
I. Gaspar, N. Michailow, A. Navarro Caldevilla, E. Ohlmer, S. Krone and G. Fettweis, „Low Complexity GFDM Receiver Based On Sparse Frequency Domain
Processing“, 77th IEEE Vehicular Technology Conference (VTC Spring'13), Dresden, Germany, June 2013
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GDFM Successive
Interference Cancellation (SIC)
64QAM, RRC, a=0.2
64QAM, RRC, a=0.4
256QAM, RRC, a=0.4
AWGN
Rayleigh
multipath
Theoretical BER of orthogonal system can be reached with SIC
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19. September 2013
Nicola Michailow
21
Slide 21
Conclusions
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Conclusions
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5G visions like the IoT have very specific application demands and
require highly asynchronous access in time and frequency
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New waveforms such as FBMC, UFMC, GFDM have very desirable
properties and are significantly more robust to temporal and spectral
fragmentation of traffic
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Two major upcoming things:
 System simulation to show benefit for fragmented traffic
 Unifying theory to explore in terms of Gabor signaling
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Demonstration of multiuser uplink
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Thank you for your attention!
www.5gnow.eu
Contact
Dr. Gerhard Wunder – gerhard.wunder@hhi.fraunhofer,de
www.hhi.fraunhofer.de/wn
Fraunhofer Heinrich Hertz Institute
Berlin, Germany
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