Communications over the THz band: Challenges and opportunities

Transcription

1 Communications over the THz band: Challenges and opportunities Presented by: Vitaly Petrov, Researcher Nano Communications Center Tampere University of Technology

2 Devices miniaturization trend q Growing interest towards the THz band Suitability for bandwidth-oriented applications Feasible for micro- and nano-scale devices Adaptation of communication techniques is required Novel research challenges raise

3 TUT Nano Communications Center 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

4 IoNT Internet of Nano Things Services Layer Context Management layer Micro-gateway Sweat nanosensors on clothing s Blood Microgateway Phone surface sensors Molecular nanonetworks Query routing nanosensors nanosensors Pathogens nanosensors Nano-sensors For environmental monitoring Chemicals Allergens EM nano communicatio n

5 Part 1. Motivation to go for high frequencies

6 Path loss and capacity trade offs 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 L P ( f, d) =! # " 4π fd c 0 $ & % 2 C = Blog 2 (1+ SNR)

7 Practical benefits 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

8 Interest growth in numbers Industry 2008: IEEE THz Interest Group (IG) 2013: IG upgraded to a Study Group on 100G 2014: Task Group.3d has been established Academia Workshops at INFOCOM and ICC Symposiums at GLOBECOM and ICC IEEE Transactions on THz, 2 Special Issues in JSAC Over 300 contributions More than 500 articles Several proofs of concept for elements

9 Definition of the THz band Frequency range Wavelengths Industry, IEEE d THz 1 mm 100 µm Academia THz 3 mm 30 µm Smart academia THz 5 mm 30 µm Current presentation Major focus: THz Primary: 3 mm 100 µm

10 Part 2. Enabling technologies

11 Macro generators of the THz radiation 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. Size and power requirements Poor performance at room temperature *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

12 Graphene and Carbon Nano Tubes (CNTs) 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) Feasibility of micro- and nano-scale antennas

13 Proposal 1. Resonant-tunneling diode + voltage oscillator q Significantly decrease the size of THz signal generators and detectors By Rohm, Japan, 2011* Frequency: 300 GHz Estimated price: 1.3 USD Achieved rate: 1.5 Gbps Estimated rate: 30 Gbps Size: 1.5 x 3 cm * Rohm Semiconductor Press-release, November 2011

14 Proposal 2. Optical rectification for continuous-wave terahertz emission q Significantly decrease the size of THz antennas By Astar, Singapore and Imperial College, London in 2012* Size of few hundreds nanometers Operational at room temperature* Size: 255 х 341 nm *H. Tanoto et al., Greatly enhanced continuous-wave terahertz emission by nanoelectrodes in a photoconductive photomixer, Nature Photonics, January 2012

15 Proposal 3. SPP waves and plasmonic antennas q Enhance the performance of THz signal generators and detectors 1. Increase efficiency 2. Decrease losses In theory, operational at room temperature* By Georgia Tech, USA, 2012 * 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

16 Part 3. Prospective applications and user scenarios

17 Ubiquitous connectivity Converged infrastructure for Personal Area Networking

18 High speed data transmission Current: q E.g. HD, 4K, 8K video transmission Camera/Coder GHz channel Smartphone Proposed: Camera THz channel Smartphone ü Solution for head-on displays Cost and complexity minimisation Latency decrease

19 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

20 Security-sensitive communications q Health monitoring, E-payments, etc. Fast signal degradation with distance Substantial bandwidth for almost any handshakes Beneficial to study the suitability of: PHY layer security ID-based crypto systems

21 Part 4. Summary, open challenges and future research directions

22 Primary research challenges (1) 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

23 Primary research challenges (2) q Lower link: Principal selection of MCS type Limitations of On/Off keying modulation Applicability of IEEE ac-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 Applicability assessment for certain user scenarios

24 TUT ongoing activities 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