Department of Electronics and Communications Engineering

Feasibility Study of the THz Band for Communications between Wearable

Electronics

Presented by: Vitaly Petrov, Researcher

Nano Communications Center Tampere University of Technology

Department of Electronics and Communications Engineering

Ubiquitous connectivity

Converged infrastructure for Personal Area Networking

Department of Electronics and Communications Engineering

Molecular nanonetworks

Micro- gateway

nano-sensors

on clothing

s Phone surface sensors

–

Context Management layer

Query routing

EM – nano communication

Micro-gateway

Pathogens Chemicals

Sweat

Blood

Allergens

nano-sensors

nano-sensors

nano-sensors

Services Layer

Nano-sensors For

environmental monitoring

IoNT – Internet of Nano Things

Department of Electronics and Communications Engineering

q  Growing interest towards the THz band §  Feasible for micro- and nano-scale devices §  Smaller devices è smaller Tx/Rx è smaller

antennas è higher frequencies

Devices miniaturization trend

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§  Adaptation of communication techniques is required §  Novel research challenges raise

E. g. 1 THz è 0.3 mm wavelength

Department of Electronics and Communications Engineering

Definitions of the THz band

Frequency range Wavelengths Industry, IEEE 802.15.3d 0.3 – 3 THz 1 mm – 100 µm

Academia 0.1 – 10 THz 3 mm – 30 µm

Smart academia 0.06 – 10 THz 5 mm – 30 µm

Current presentation Major focus: 0.1 – 3 THz Primary: 3 mm – 100 µm

Department of Electronics and Communications Engineering

Industry 2008: IEEE 802.15 THz Interest Group (IG)

2013: IG upgraded to a Study Group on 100G

2014: Task Group .3d has been established

Over 300 contributions

Interest growth in numbers

Academia

§ Workshops at INFOCOM and ICC

§  Symposiums at GLOBECOM and ICC

§  IEEE Transactions on THz, 2 Special Issues in JSAC

More than 500 articles

Several proofs of concept for elements

Department of Electronics and Communications Engineering

q  One atom thick carbon material q  Produced by Andre Geim,

K. Novoselov in 2004 §  Nobel prize 2010

q  Major electrical property: §  Extremely high electrical conductivity

q  Derivatives: §  Carbon Nanotubes (CNT) §  Graphene Nanoribbons (GNR)

Enabling technologies Graphene and Carbon Nano Tubes (CNTs)

Feasibility of micro- and nano-scale antennas

Department of Electronics and Communications Engineering

q  Spatial loss §  E.g. free-space loss for

omnidirectional antennas q  Molecular absorption loss

§  Frequency-selective channel (!!!) §  Due to internally vibrating molecules on

frequencies similar to signal ones §  Feature of the THz Band §  Abs. coefficients è from HITRAN database

THz channel properties (1) Propagation and path loss

LP f ,d( ) = 4π fdc0

!

"#

$

%&

2

( )( )df

dfLA ,1,

τ= ( ) ( )dfkdfk IGIGeedf ,,)(, ∑==

−−τ

LT f ,d( ) = LP f ,d( )+ LA f ,d( )

Department of Electronics and Communications Engineering

q  Feature of the THz band §  Molecules convert part of the

absorbed energy into kinetic energy

THz channel properties (2) Molecular absorption noise

PN f ,d( ) = kBNM f( )= kBT 1−τ f ,d( )"# $%=

= kBT 1− e−k f( )d"

#$%2 4 6 8 10

260

240

220

200

d = 0.01m.

d = 0.1m.

Molecular noise, dB

f, frequency, THz

Noise highly fluctuates through the frequencies

Range of minimal noise level

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THz channel is frequency-selective

Window Frequency range Bandwidth Half pulse duration 1 0.10 – 0.54 THz 440 GHz 1.48 ps 2 0.63 – 0.72 THz 95 GHz 6.53 ps 3 0.76 – 0.98 THz 126 GHz 4.92 ps 4 7.07 – 7.23 THz 160 GHz 2.59 ps 5 7.75 – 7.88 THz 130 GHz 3.88 ps

0 2 4 6 8

50

100

150

200 d = 0.01m.

d = 0.1m.

d = 1m.

Overall loss, dB

f, frequency, Hz

q  First transparency window is the most promising

Study 0.1 – 0.54 THz in-depth

Department of Electronics and Communications Engineering

q  ~20dB gain over 0.1 – 3 THz (!) §  (10 times in amplitude, 100 in power) §  Sufficient for decoding with major MCS §  Suggested for transmission over

“longer” distances: ≥1 cm

First transparency window, 0.1 – 0.54 THz

0.2 0.4 0.6 0.820

40

60

80

100

120d = 0.01m.

d = 0.1m.

d = 1m.

Overall loss, dB

f, frequency, Hz

Department of Electronics and Communications Engineering

Range/capacity trade off Small channels

1 103 0.01 0.1 1

1

10

1000.10-0.54Thz

0.44-0.54Thz

0.49-0.54Thz

0.10-0.20Thz

0.10-0.15Thz

SNR, dB

d, distance, m.

0.01 0.11 10

8

1 109

1 1010

1 1011

1 1012

1 1013

0.10-0.54Thz

0.44-0.54Thz

0.49-0.54Thz

0.10-0.20Thz

0.10-0.15Thz

C, capacity, bits/s.

d, distance, m.

q  For 10 cm distance: Frequency range (bandwidth) SNR Capacity

0.1 – 0.54 THz (440 GHz) 20 dB 500 Gbps

0.1 – 0.2 THz (100 GHz) 33 dB 300 Gbps

0.1 – 0.15 THz (50 GHz) 35 dB 200 Gbps

Enabling complex MCSs

Department of Electronics and Communications Engineering

Range/capacity trade off Tiny channels

0.01 0.1 1 10 1001

10

1001MHz

10MHz

100MHz

1000MHz

SNR, dB

d, distance, m.0.1 1 10

1 106

1 108

1 1010

1MHz

10MHz

100MHz

1000MHz

C, capacity

d, distance, m.

q  For SNR = 10 dB, Smart metering case Frequency range (bandwidth) Range Capacity (at 1 m)

~0.1 THz (1000 MHz) 2 m 8 Gbps

~0.1 THz (10 MHz) 6 m 0.1 Gbps (100 Mbps)

~0.1 THz (1 MHz) 15 m 0.01 Gbps (10 Mbps)

Applicable for sensing applications

Department of Electronics and Communications Engineering

q  Limitations of continuous-wave MCS: §  Generating carrier at 1-2THz and higher §  Filtering at higher frequencies §  Energy efficiency Advances in physics are needed

q  On/Off keying q  Transmitting s(t):

§  s(t)=1 è Pulse §  s(t)=0 è Silence

“Low-complex” hardware

Modulation and Coding On/Off Keying simple MCS

1 1 0 01

tt t t t t

...

v v v v

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q  Asymmetric channel: pE1 ≠ pE0 q  Set of threshold è optimisation problem q  BER can be lower than 0.001

BER and throughput estimation for OOK

FEC codes are applicable

0 0.2 0.4 0.6 0.8 10.16

0.18

0.2

0.22

0.24

0.26

Throughput, v=0.0ps

Throughput, v=0.4ps

Throughput, v=0.8ps

Throughput, v=1.2ps

T, thoughput, Tbps

TP, relative energy detection threshold0 0.2 0.4 0.6 0.8 1

1 104

1 103

0.01

0.1

1

v=0.0ps

v=0.4ps

v=0.8ps

v=1.2ps

pE, bit error probability

TP, relative energy detection threshold

Department of Electronics and Communications Engineering

q  Fundamental PHY: Feasibility of miniaturised components design and manufacturing §  THz signal generators §  Tx/Rx §  Antennas

q  Advanced PHY: Rapid improvements study §  Feasibility of carriers-based communications §  Directivity is vital and needed soon

(mitigation of high propagation losses) §  Antenna arrays and (massive) MIMO

Summary Primary research challenges (1)

Department of Electronics and Communications Engineering

q  Lower link: Principal selection of MCS type §  Limitations of On/Off keying modulation §  Applicability of IEEE 802.11ac-based

signaling (minimize time-to-market) §  Suitability of full-duplex MAC

q  Upper link and higher layers: System level §  Peers discovery (especially, with directional

antennas), angle of arrival, etc. §  Addressing for massive amount of devices §  Security and Privacy issues

Summary Primary research challenges (2)

Applicability assessment for certain user scenarios