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doc.: IEEE 802.15-19-0293—01-0thz_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.
© 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
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
© 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
Duration: 7/2017 – 12/2019
ICT-09-2017 – Networking research beyond 5G
grant agreement no. 761794
© 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
© 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 GHz – 1000 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
THz
300
B <= 1 GHz B <= 10 GHz B <= 100 GHz
© Fraunhofer HHI | 16.07.2019 | 6
Applications for THz wireless networks
Applications can be classified in 3 generic technology scenarios:
Quasi-Omnidirectional
Point-to-Multi-Point (PtMP)
Point-to-Point (PtP)
© Fraunhofer HHI | 16.07.2019 | 7
Techniques for THz upconversion
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
© Fraunhofer HHI | 16.07.2019 | 8
OUTLINE
Hybrid optical-THz wireless networks beyond 5G
100 Gb/s offline experiments
100 Gb/s real-time experiments
Conclusions
© Fraunhofer HHI | 16.07.2019 | 9
275-325 GHz THz frontend waveguide modules (Tx/Rx)
(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-convers ion
LO generation using 2-stage multipliers (x12, x3) and direct-conversion architecture
© Fraunhofer HHI | 16.07.2019 | 10
DSP Algorithms and Modem Functions
THz PtP LoS channel is very similar to fibre-optical channel: relatively flat within the bandwidth of a signal)
Typical single-carrier PHY DSP for optical channels can also be used for THz PtP LoS channel (but additional adaptivity required)
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. fr
on
ten
ds
© Fraunhofer HHI | 16.07.2019 | 11
All-electronic 100 Gb/s THz wireless transmission experiment (offline)
One spatial channel Distance (wireless link): 58 cm Radiated THz power at Tx: ~14 dBm 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
300 GHz carrier / 23 dBi antennas
© Fraunhofer HHI | 16.07.2019 | 12
Alternative setup: 100 Gb/s transmission using optical upconversion
Two tones are generated with a frequency separation of ~300 GHz in the C-band to generate a corresponding carrier through a process called ‘photomixing’
The input power into the THz transmitter determines the radiated THz power
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
© Fraunhofer HHI | 16.07.2019 | 13
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)
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
© Fraunhofer HHI | 16.07.2019 | 14
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)
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
© Fraunhofer HHI | 16.07.2019 | 15
100 Gb/s offline experiments: ResultsBER performance
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
© Fraunhofer HHI | 16.07.2019 | 16
100 Gb/s offline experiments: ResultsBER performance
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
© Fraunhofer HHI | 16.07.2019 | 17
100 Gb/s offline experiments: ResultsBER performance
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
© Fraunhofer HHI | 16.07.2019 | 18
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
-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 circleQuad
ratu
re c
om
ponen
t (a
.u.)
Inphase component (a.u.)
© Fraunhofer HHI | 16.07.2019 | 19
OUTLINE
Hybrid optical-THz networks beyond 5G
100 Gb/s offline experiments
100 Gb/s real-time experiments
Conclusions
© Fraunhofer HHI | 16.07.2019 | 20
100 Gb/s real-time THz wireless transmission2x2 MIMO setup
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
100 Gb/s Real-Time BBU
100 Gb/s Client
Interface
From/ToEthernet
Fibre-optical BBU, originally designed for 34 GBd PDM-QPSK, is used for a THz wireless link
To carry the 34 GBd PDM-QPSK data over a 50 cm-long wireless link, two pairs of Tx/Rx THz elements are used
Each Tx/Rx pair transports one spatial channel
The BBU’s DSP scheme is a standard approach used for contemporary fiber-based 100 Gb/s and 200 GB/s solutions
O/Einterface
© Fraunhofer HHI | 16.07.2019 | 21
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 ·10-3
During the duration of the experiment, noerroneous bits were found after decoding
Error-free transmission ensured by SD-FEC scheme
0 30 60 90 120 1501E-03
1E-02
1E-01
Pre
-FE
C B
ER
Elapsed time (hours)
Pre-FEC BER
SD-FEC
© Fraunhofer HHI | 16.07.2019 | 22
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) *
* This work has been submitted to IEEE Globecom 2019
© Fraunhofer HHI | 16.07.2019 | 23
Towards high-capacity THz wireless networks beyond 5GConclusions
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
Experimental demonstrations of error-free 100-Gb/s THz Wireless Transmiss ion 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
© Fraunhofer HHI | 16.07.2019 | 24
Towards the standardization of THz communicationsConclusions
Fraunhofer HHI would welcome 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 been experimentallydemonstrated for high-capacity data transmission (>100 Gb/s)
© Fraunhofer HHI | 16.07.2019 | 25
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.
