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doc.: IEEE 802.15-19-0278—00-0thz_100 Gbs_Real-Time_THz_Wireless_Link
11 March 2019
July 2019
Carlos Castro, Fraunhofer HHISlide 1
Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)
Submission Title: 100 Gb/s Real-Time THz Wireless Link Demonstration
Date Submitted: 15 July 2019
Source: Carlos Castro Company: Fraunhofer Heinrich Hertz Institute
Address: Einsteinufer 37, 10587 Berlin, Germany
Voice: +49 30 31002-659 FAX: +49 30 31002-213, E-Mail: [email protected]
Re: n/a
Abstract: In order to demonstrate the feasibility of THz systems for a future beyond 5G networks, we have
constructed a 100 Gb/s real-time spatially-multiplexed THz wireless link, which operates at a carrier
frequency of 300 GHz, and investigated its transmission performance using a broadband digital-coherent
modem. In addition, we provide an overview of our previous >100Gb/s transmission experiments to
highlight the special characteristics and considerations for purely wireless and for hybrid optic-THz links.
Purpose: Information of the Technical Advisory Group THz
Notice: This document has been prepared to assist the IEEE P802.15. It is offered as a basis for
discussion and is not binding on the contributing individual(s) or organization(s). The material in this
document is subject to change in form and content after further study. The contributor(s) reserve(s) the right
to add, amend or withdraw material contained herein.
Release: The contributor acknowledges and accepts that this contribution becomes the property of IEEE
and may be made publicly available by P802.15.
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© Fraunhofer HHI | 16.07.2019 | 2
100 GB/S REAL-TIME THZ WIRELESS LINK DEMONSTRATION
IEEE 802 Plenary Session,
121st IEEE 802.15 WSN Meeting – Austria Congress Centre
Vienna, Austria – 16.07.2019
[email protected]
Carlos Castro1, Robert Elschner1, Thomas Merkle2, Colja Schubert1
1. Fraunhofer Heinrich Hertz Institute, Einsteinufer 37, 10587 Berlin, Germany
2. Fraunhofer-Institut für Angewandte Festkörperphysik, Tullastraße 72, 79108 Freiburg im Breisgau, Germany
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© Fraunhofer HHI | 16.07.2019 | 3
H2020 EU TERRANOVA: Terabit/s Wireless Connectivity by TeraHertz innovative technologies to deliver Optical Network Quality of Experience in Systems beyond 5G
[email protected]
Duration: 7/2017 – 12/2019
ICT-09-2017 – Networking research beyond 5G
grant agreement no. 761794
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© Fraunhofer HHI | 16.07.2019 | 4
OUTLINE
◼ Hybrid optical-THz wireless networks beyond 5G
◼ 100 Gb/s offline experiments
◼ 100 Gb/s real-time experiments
◼ Conclusions
[email protected]
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© Fraunhofer HHI | 16.07.2019 | 5
MotivationTHz communications as enabler for flexible hybrid networks beyond 5G
▪ THz wireless data transmission at carrier frequencies in the 100 – 500 GHz range
▪ Large bandwidth, compatible with state-of-the-art fibre-optical transmission systems
▪ This allows to design flexible hybrid optical-THz wireless networks beyond 5G with seamless interconnections and > 100 Gb/s link capacity
[email protected]
THz
300
B <= 1 GHz B <= 10 GHz B <= 100 GHz
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© Fraunhofer HHI | 16.07.2019 | 6
Applications for hybrid optical-THz wireless networks
[email protected]
▪ Applications can be classified in 3 generic technology scenarios:
▪ Point-to-Point (PtP)
▪ Point-to-Multi-Point (PtMP)
▪ Quasi-Omnidirectional
▪ We will focus on PtP in this talk
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Hybrid optical-THz wireless PtP Links
▪ Co-integration of optical frontends and THz frontends allows seamless interconnections between legacy fibre infrastructure and THz wireless links
▪ Baseband unit performs joint impairment mitigation for hybrid link
[email protected]
THz Wireless Link
Antenna(s)
BasebandUnit
Fibre
O/E RF Frontend
E/O RF Frontend
BasebandUnit
Fibre
MA
C
PH
Y
AD
C/D
AC
Modem
Signal Processing RF Integration
O/E
λ1
λ2
λ3
λ4
O/E
ᵠᵠᵠᵠ
Beam steering
Frontend Array antenna
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© Fraunhofer HHI | 16.07.2019 | 8
Techniques for THz upconversion
[email protected]
▪ Electrical THz upconversion
Electrical Mixer
Antenna
Data signal
Electr. LO (300 GHz)
THz channel
▪ Optical THz upconversion
Optical Modulation
Pin-PD
192.7 193.0 193.3
cw carrier
Opt
ical
Sig
nal
Frequency / THz
data
300 GHzData signal
Laser (193 THz)
THz channelLaser (193 THz + 300 GHz)
Antenne
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© Fraunhofer HHI | 16.07.2019 | 9
OUTLINE
◼ Hybrid optical-THz wireless networks beyond 5G
◼ 100 Gb/s offline experiments
◼ 100 Gb/s real-time experiments
◼ Conclusions
[email protected]
Page 10
© Fraunhofer HHI | 16.07.2019 | 10
275-325 GHz THz frontend waveguide modules (Tx/Rx)
[email protected]
(IF-I, IF-Q)
LO
RxM185X12W
Tx
(IF-I, IF-Q)
M185X12W
M170M03H-RX
LO
275-325
GHz
8.333 GHz 8.333 GHz
IF-I
IF-QRFout (300 GHz)
LOin (100 GHz)DC
TX MMIC
Fout
DC
Fin
Fout Fin
DC
Multiplier-by-12 Module
TX Frontend
M170M03H-TX
▪ All-electronic up- and down-conversion:LO generation using 2-stage multipliers (x12, x3) and direct-conversion architecture
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© Fraunhofer HHI | 16.07.2019 | 11
Hybrid optical-THz wireless link simulations
XIXQ
YIYQ
Tx Laser
TxDSP
Optical DP-IQ
Modulator
XI
XQYI
YQ
LO Laser
MIMO Fiber
Channel
Optical CoherentFrontend
LO
THz Up-Mixer
THz Up-Mixer
XIXQ
YIYQ
RxDSP
THz Down-Mixer
THz Down-Mixer
LOSISO THzChannel
(incl. antennas
SISO THzChannel
(incl. antennas10 km optical
THz 2x2 MIMO Wireless Channel
Simulation Parameter Value
Symbol rate 32 GBd
THz transmit power -14 dBm
Optical transmit power -3 dBm
OSNR at optical/THz interface 36 dB
Optical laser linewidth 100 kHz
Optical frequency offset [-1 GHz … 1 GHz]
Optical polarization rotation Full Poincaré sphere
Chromatic dispersion 17 ps/nm/km
Optical link length 10 km
THz phase noise Measured values
THz frequency offset [-100 MHz … 100 MHz]
[email protected]
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© Fraunhofer HHI | 16.07.2019 | 12
Hybrid optical-THz wireless link simulations
[email protected]
10 100 1,000
0
10
20
30
40
50
SN
R (
dB
)
Distance THz link (m)
Atm. loss
No atm. loss
34 dB OSNR0.1 nm
64-QAM
16-QAM
4-QAM
▪ For the most part, the overall SNRof the hybrid optical-THz wirelesswill be determined either by theTHz link or by the optical link.
▪ Based on SNR estimations, wirelesstransmission over 800 m can still beachieved with 16-QAM at thistransmit power
▪ Can we use a single DSP for jointmitigation of impairments from theoptical and the THz link?
-14 dBm THz Tx power / 55 dBi antennas
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DSP Algorithms and Modem Functions
▪ THz PtP LoS channel is very similar to fibre-optical channel
▪ Typical single-carrier PHY DSP for optical channels can also be used for THz PtP LoS channel (but additional adaptivity required), as well as for the combined fibre-optical / THz-wireless channel
[email protected]
Map
ping
Trai
ning
-seq
uenc
ein
sert
ion
Puls
e sh
apin
g
Pre-
emph
asis
Chan
nel
DAC
DAC
FE c
orre
ctio
ns
Fram
e Sy
nchr
oniz
atio
n
Carr
ier-
offs
et c
ompe
nsat
ion
Trai
ning
-Aid
edT/
2-sp
aced
Equ
aliz
er
Carr
ier-
Phas
e Es
timat
ion
Carr
ier-
Phas
e Es
timat
ion
T-sp
aced
I/Q
Equ
aliz
er
Dem
appi
ng&
Dec
isio
n
BER
coun
ting
Tx DSP Rx DSP
Rand
om b
itse
quen
cege
nera
tion
DA
Cs
AD
Cs
Hyb
rid
lin
k in
cl.
fro
nte
nd
s
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© Fraunhofer HHI | 16.07.2019 | 14
XIXQ
YIYQ
Tx Laser
TxDSP
Optical DP-IQ
Modulator
XI
XQYI
YQ
LO Laser
MIMO Fiber
Channel
Optical CoherentFrontend
LO
THz Up-Mixer
THz Up-Mixer
XIXQ
YIYQ
RxDSP
THz Down-Mixer
THz Down-Mixer
LOSISO THzChannel
(incl. antennas
SISO THzChannel
(incl. antennas
Hybrid channelseems to be limitedby transmissionimpairments in theTHz link
1,00E-07
1,00E-06
1,00E-05
1,00E-04
1,00E-03
1,00E-02
1,00E-01
1,00E+00
0 5 10 15 20 25 30
BER
SNR at Rx (dB)
32 Gbd 16-QAM
Theory Es/N0 Hybrid optic-THz system
Only THz system Only optical system
SD-FEC
SNR at Rx (dB)
BE
R
32 GBd 16-QAM
hybrid
THz-only
optical-onlytheoretical
1,00E-07
1,00E-06
1,00E-05
1,00E-04
1,00E-03
1,00E-02
1,00E-01
1,00E+00
0 5 10 15 20
BE
R
SNR at Rx (dB)
32 GBd 4-QAM
Theory Es/N0 Hybrid optic-THz system
Only THz system Only optical system
SD-FEC
SNR at Rx (dB)
BE
R
32 GBd 4-QAM
theoretical
hybrid
THz-only
optical-only
SimulationsSimulations
Joint impairment mitigation for hybrid optical-THz Links
[email protected]
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© Fraunhofer HHI | 16.07.2019 | 15
All-electronic 100 Gb/s THz wireless transmission experiment (offline)
▪ 32 Gbaud – 16 QAM▪ Raw 128 Gb/s @ BER = 1.110-2
▪ Net 100 Gb/s FEC-corrected
DAC
Att.
Att.
x12 x3
f = 8.11 – 8.71 GHz
f = 2.625 GHz
φ
dlink
RT Scope
x12x3
Offline
DSP
Rx
module
Tx
module
[email protected]
300 GHz carrier / 23 dBi antennas
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© Fraunhofer HHI | 16.07.2019 | 16
Alternative setup: 100 Gb/s transmission using optical upconversion
◼ Tones are generated with a frequency separation of ~300 GHz in the C-band
[email protected]
192.7 193.0 193.3
cw carrier
Opt
ical
Sig
nal
Frequency / THz
data
Laser1
Laser2
DAC
3 dB Tx Rx
0.5 m
Scope
x12
8.368 GHz
Modulated signal
Continuous wave signal
PIN-PDEDFA
EDFA
EDFA
EDFAIQ mod
300 GHz
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© Fraunhofer HHI | 16.07.2019 | 17
Experimental setupPIN-PD THz emitter
◼ Flat frequency response at frequencies around 300 GHz
◼ Hyper-hemispherical silicon lens couples the THz radiation into free space
◼ Antenna gain = 21 dBi @ 300 GHz (optical input power: up to 15 dBm)
[email protected]
200 400 600 800 1000-30
-25
-20
-15
-10
-5
260 280 300 320 340
-18
-16
-14
THz-Emission at 12 dBm optical power
THz
po
wer
(d
Bm
)Frequency (GHz)
300 GHz band
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© Fraunhofer HHI | 16.07.2019 | 18
Experimental setupTHz receiver and complete setup
▪ ~50 GHz bandwidth centered around 300 GHz
▪ Horn antenna
▪ Antenna gain = 23 dBi @ 300 GHz
[email protected]
▪ Experimental setup with lenses between THz emitter and THz Rx
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© Fraunhofer HHI | 16.07.2019 | 19
100 Gb/s offline experiments: ResultsBER performance
◼ BER performance of a wireless 64 Gb/s QPSK and 128 Gb/s 16-QAM THz system
◼ SD-FEC threshold 2.2E-2: Net rates of 50 Gb/s (QPSK) and 100 Gb/s (16QAM)
[email protected]
6 9 12 15
-37.5 -33.0 -28.6 -24.1
1E-7
1E-6
1E-5
1E-4
0.001
0.01
0.1
THz power (dBm)
64 Gb/s QPSK
128 Gb/s 16QAM
FEC ThresholdBE
ROptical power (dBm)
"Error-free"
BER < 1E-7
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© Fraunhofer HHI | 16.07.2019 | 20
100 Gb/s offline experiments: ResultsBER performance
[email protected]
6 9 12 15
-37.5 -33.0 -28.6 -24.1
1E-7
1E-6
1E-5
1E-4
0.001
0.01
0.1
THz power (dBm)
64 Gb/s QPSK
128 Gb/s 16QAM
FEC ThresholdBE
ROptical power (dBm)
"Error-free"
BER < 1E-7
◼ BER performance of a wireless 64 Gb/s QPSK and 128 Gb/s 16-QAM THz system
◼ SD-FEC threshold 2.2E-2: Net rates of 50 Gb/s (QPSK) and 100 Gb/s (16QAM)
◼ Non-monotonic behavior:
▪ Increasing the Rx power does not always translate into better performance
◼ Three regions: noise-limited, optimum, non-linear
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© Fraunhofer HHI | 16.07.2019 | 21
100 Gb/s offline experiments: ResultsBER performance
[email protected]
6 9 12 15
-37.5 -33.0 -28.6 -24.1
1E-7
1E-6
1E-5
1E-4
0.001
0.01
0.1
THz power (dBm)
64 Gb/s QPSK
128 Gb/s 16QAM
FEC ThresholdBE
ROptical power (dBm)
"Error-free"
BER < 1E-7
◼ BER performance of a wireless 64 Gb/s QPSK and 128 Gb/s 16-QAM THz system
◼ SD-FEC threshold 2.2E-2: Net rates of 50 Gb/s (QPSK) and 100 Gb/s (16QAM)
◼ Non-monotonic behavior:
▪ Increasing the Rx power does not always translate into better performance
◼ Three regions: noise-limited, optimum, non-linear
Page 22
© Fraunhofer HHI | 16.07.2019 | 22
100 Gb/s offline experiments: ResultsBER performance
[email protected]
6 9 12 15
-37.5 -33.0 -28.6 -24.1
1E-7
1E-6
1E-5
1E-4
0.001
0.01
0.1
THz power (dBm)
64 Gb/s QPSK
128 Gb/s 16QAM
FEC ThresholdBE
ROptical power (dBm)
"Error-free"
BER < 1E-7
◼ BER performance of a wireless 64 Gb/s QPSK and 128 Gb/s 16-QAM THz system
◼ SD-FEC threshold 2.2E-2: Net rates of 50 Gb/s (QPSK) and 100 Gb/s (16QAM)
◼ Non-monotonic behavior:
▪ Increasing the Rx power does not always translate into better performance
◼ Three regions: noise-limited, optimum, non-linear
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© Fraunhofer HHI | 16.07.2019 | 23
100 Gb/s offline experiments: ResultsI/Q distortions
▪ The assumption that the performance worsens due to non-linearities is further investigated
▪ Modulation is turned off →unmodulated THz carrier
▪ Some non-linear compression can be observed at high received THz power levels
▪ Distortion of the circular shape
▪ Symmetric compression of the signal
▪ Improved component linearity required to support higher-order modulation formats
[email protected]
-1.5 -1.0 -0.5 0.0 0.5 1.0 1.5-1.5
-1.0
-0.5
0.0
0.5
1.0
1.5
-37,5 dBm
-33,5 dBm
-28,4 dBm
-24,1 dBm
Ideal circleQu
adra
ture
co
mp
on
ent
(a.u
.)
Inphase component (a.u.)
Page 24
© Fraunhofer HHI | 16.07.2019 | 24
OUTLINE
◼ Hybrid optical-THz networks beyond 5G
◼ 100 Gb/s offline experiments
◼ 100 Gb/s real-time experiments
◼ Conclusions
[email protected]
Page 25
© Fraunhofer HHI | 16.07.2019 | 25
100 Gb/s real-time THz wireless transmission2x2 MIMO setup
[email protected]
Carrier frequency:
8.31 GHz x 36 = 300 GHz
Tx THz
Tx THz
Rx THz
Rx THz
THz- @ 300 GhzTransmission ~
X pol
Y pol
TrafficPlatform
Breakout
Karte
LO @
8.31 GHz
over 50 cm
100Gb/s Real-Time BBU
100 Gb/s Client
Interface
From/ToEthernet
100 Gb/s Real-Time BBU2x2 MIMO Tx 2x2 MIMO RxBB AMP
◼ Fibre-optical BBU, originally designed for 34 GBdPDM-QPSK, is used for a THz wireless link
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© Fraunhofer HHI | 16.07.2019 | 26
100 Gb/s real-time THz wireless transmissionEvaluation of pre-FEC BER
▪ Long-term stable (>150h hours) pre-FEC belowSD-FEC threshold (3.4·10-2)
▪ 34.34 GBd PDM QPSK
▪ 50 cm THz transmission at 300 GHz
▪ Mean pre-FEC BER around 8.2 ·10-2
▪ During the duration of the experiment, noerroneous bits were found after decoding
▪ Error-free transmission ensured by SD-FEC scheme
[email protected]
0 30 60 90 120 1501E-03
1E-02
1E-01
Pre
-FE
C B
ER
Elapsed time (hours)
Pre-FEC BER
SD-FEC
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© Fraunhofer HHI | 16.07.2019 | 27
100 Gb/s real-time THz wireless transmissionExperiments using a 100 GbE traffic generator
▪ Latency from BBU (cross-connection + DSP) and THz system: ~8.5 µs *
▪ Frame loss rate: 1.8 frames per minute (0.03 fps) *
▪ Measured throughput: 86.5 – 98.08 Gb/s (depending on the frame size) *
[email protected]
* This work has been submitted to IEEE Globecom 2019
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© Fraunhofer HHI | 16.07.2019 | 28
Conclusions
Towards high-capacity hybrid optical-THz wireless networks beyond 5G
▪ A wide range of applications can be envisioned for THz wireless links with high capacity and high range, in particular in hybrid optical-THz wireless networks beyond 5G
▪ Simulations indicate potential for >100 Gb/s capacity over ~ 1 km in such links
▪ Experimental demonstrations of error-free 100-Gb/s THz Wireless Transmission over 0.5 m
▪ Offline: SISO 32-GBd 16QAM offline
▪ Real time: 2x2 MIMO 32-GBd QPSK
▪ Required next steps in order to increase capacity, range and flexibility:
▪ Use high-gain antennas (55 dBi)
▪ Design highly linear, high output power electronic front-ends for larger constellation sizes
▪ Adaptive PHY DSP to cope with channel dynamics
▪ Next research goal: Use 100 Gb/s real-time THz link demonstrator in real network scenarios
[email protected]
Page 29
© Fraunhofer HHI | 16.07.2019 | 29
Conclusions
Towards the standardization of hybrid optic-THz communications
▪ Fraunhofer would support the formation of a Study Group on THz communications
▪ Objective: High-capacity (>100 Gb/s) THz links in the range of hundreds of meters within a hybridoptic-THz wireless network scenario
▪ Use cases: Wireless fronthaul/backhaul links to provide an alternative point-to-point link in casefiber deployment is too complicated/expensive due to the terrain‘s characteristics
▪ Technical SotA: Stability and technical feasibility of THz transmission link has beenexperimentally demonstrated for high-capacity data transmission (>100 Gb/s)
[email protected]
Page 30
© Fraunhofer HHI | 16.07.2019 | 30
Contact:
MSc. Carlos [email protected] +49 30 31002 659
Einsteinufer 3710587 Berlin
Fraunhofer Institute for Telecommunications, Heinrich Hertz Institute, HHI
WE PUT SCIENCE INTO ACTION.
This work was supported by the Fraunhofer Internal Programs under Grant No. MAVO 836 966 and by the EC Horizon 2020 Research and Innovation Program under grant agreement No. 761794.
[email protected]
