communications over the thz band: challenges and … over the thz band: challenges and opportunities...
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Department of Electronics and Communications Engineering
Communications over the THz band: Challenges and opportunities
Presented by: Vitaly Petrov, Researcher
Nano Communications Center Tampere University of Technology
Department of Electronics and Communications Engineering
q Growing interest towards the THz band § Suitability for bandwidth-oriented applications § Feasible for micro- and nano-scale devices
Devices miniaturization trend
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§ Adaptation of communication techniques is required § Novel research challenges raise
Department of Electronics and Communications Engineering
q Established in late 2012 via an Academy of Finland “Finnish Distinguished Professor (FiDiPro)” Program
q Co-supervised by Prof. Yevgeni Koucheryavy (TUT) and Prof. Ian F. Akyildiz (Georgia Tech, USA)
q Staff: § Currently 5 (Senior) researchers + MSc students
q Major focus: - Graphene-enabled networks (THz band) - Cross-connectivity with biological components
TUT Nano Communications Center
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
PathogensChemicals
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
Part 1. Motivation to go for high frequencies
Department of Electronics and Communications Engineering
q Spatial loss § E.g. free-space loss for
omnidirectional antennas q Shannon Capacity Limit
§ Link-level performance in case of “best” modulation and coding scheme
Path loss and capacity trade offs
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Department of Electronics and Communications Engineering
q Smaller antenna size
§ λ/2 and λ/4 for 10 MHz = 15 (7.5) m § λ/2 and λ/4 for 1 GHz = 15 (7.5) cm § λ/2 and λ/4 for 1 THz = 150 (75) mcm
q MIMO (!) § Massive MIMO è Higher capacity § Adaptive MIMO è Interference cancellation
q Devices miniaturization § Micro and Nano Scale networks
Practical benefits
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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
Definition 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
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Part 2. Enabling technologies
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q Equipment is available from late 1990s* 1. Lasers:
§ Quantum cascade lasers (QCL) § Far infrared lasers (FIR)
2. Free electron based: § Schottky diodes § Travelling Wave
Tubes (TWT), etc.
Macro generators of the THz radiation
*D. Grischkowsky et al., "Far-Infrared Time-Domain Spectroscopy with TeraHz Beams of Dielectrics and Semiconductors,” The Journal of the Optical Society of America B, October 1990
Poor performance at room temperature
Size and power requirements
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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)
Graphene and Carbon Nano Tubes (CNTs)
Feasibility of micro- and nano-scale antennas
Department of Electronics and Communications Engineering
q Significantly decrease the size of THz signal generators and detectors
§ By Rohm, Japan, 2011* § Frequency: 300 GHz § Estimated price: 1.3 USD
Proposal 1. Resonant-tunneling diode + voltage oscillator
* Rohm Semiconductor Press-release, November 2011
Achieved rate: 1.5 Gbps Estimated rate: 30 Gbps
Size: 1.5 x 3 cm
Department of Electronics and Communications Engineering
q Significantly decrease the size of THz antennas
§ By Astar, Singapore and Imperial College, London in 2012*
§ Size of few hundreds nanometers
Proposal 2. Optical rectification for continuous-wave terahertz emission
*H. Tanoto et al., “Greatly enhanced continuous-wave terahertz emission by nano-electrodes in a photoconductive photomixer”, Nature Photonics, January 2012
Size: 255 х 341 nm Operational at room temperature*
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q Enhance the performance of THz signal generators and detectors
1. Increase efficiency
2. Decrease losses
Proposal 3. SPP waves and plasmonic antennas
* J. M. Jornet and I. F. Akyildiz, "Graphene-based Plasmonic Nano-antenna for Terahertz Band Communication in Nanonetworks," IEEE Journal on Selected Areas in Communications (JSAC), December 2013
In theory, operational at room temperature* By Georgia Tech, USA, 2012
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Part 3. Prospective applications and user scenarios
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Ubiquitous connectivity
Converged infrastructure for Personal Area Networking
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High speed data transmission
Current:
q E.g. HD, 4K, 8K video transmission
Proposed:
Camera/Coder
Smartphone
Camera
Smartphone
GHz channel
THz channel
ü Solution for head-on displays § Cost and complexity minimisation § Latency decrease
Department of Electronics and Communications Engineering
Board-to-Board and Core-to-Cache communications
q Solves complexity and scalability issues q Homogeneous system structure q Capacity of the THz channel is sufficient for
core-to-cache communications as well
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q Health monitoring, E-payments, etc. § Fast signal degradation with distance § Substantial bandwidth for almost any
handshakes
Security-sensitive communications
Beneficial to study the suitability of: § PHY layer security § ID-based crypto systems
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Part 4. Summary, open challenges and future research directions
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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
Primary research challenges (1)
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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
Primary research challenges (2)
Applicability assessment for certain user scenarios
Department of Electronics and Communications Engineering
v First generation systems: primitive, pulse-based, 1-2 m coverage Released in fall 2014:
q Protocol-level simulator to explore system dynamics § COMSOL, etc. are too heavy § Referencing validated channel models § Feasibility study of different channel
access schemes and protocols q Enhanced analytical models
§ BER estimation, peer discovery, etc. To be released in 2015:
q System-level simulator q Assessment of the THz band for anticipated usage scenarios
§ Board-to-Board § HD video transmission
TUT ongoing activities