Faster, Smarter, Greener Intelligent Reflecting Surface for 6G - PowerPoint PPT Presentation

Faster, Smarter, Greener ： Intelligent Reflecting Surface for 6G Communications Qingqing Wu (e-mail: qingqingwu@um.edu.mo) Faster, Smarter, Greener Oct. 13, 2020 AIMCOM2, ICNP, 2020 1

Qingqing Wu, University of Macau Outline ❑ Part 1: Introduction of Intelligent Reflecting Surface (IRS) ➢ Motivation ➢ Hardware architecture ➢ Reflection and channel models ➢ Applications and industry initiatives ➢ Comparison with existing technologies ❑ Part 2: Major Challenges ➢ IRS reflection optimization ➢ IRS channel estimation ➢ IRS deployment ❑ Part 3: Conclusions and Future Work Directions AIMCOM2, ICNP, 2020 2

Qingqing Wu, University of Macau Outline ❑ Part 1: Introduction of Intelligent Reflecting Surface (IRS) ➢ Motivation ➢ Hardware architecture ➢ Reflection and channel models ➢ Applications and industry initiatives ➢ Comparison with existing technologies ❑ Part 2: Major Challenges ➢ IRS reflection optimization ➢ IRS channel estimation ➢ IRS deployment ❑ Part 3: Conclusions and Future Work Directions AIMCOM2, ICNP, 2020 3

Why 6G? Motivation Qingqing Wu, University of Macau One Decade for a Leap in Wireless One Decade for a Leap New Communication Requirements VR AR File transfers Cost, Energy, Complexity AIMCOM2, ICNP, 2020 4

Motivation Qingqing Wu, University of Macau What’s New in 6G? 𝐷 = log 1 + 𝐼𝑄 𝜏 2 Base station Wireless channel: H User 𝐼 Random  𝐼 Controllable in 6G ☺ Claude Shannon （ 1916-2001 ） “ the father of information theory ” ❑ Past decades: wireless channel H is only treated random and uncontrollable! ❑ Promising 6G paradigm: Smart and Reconfigurable Wireless Environment ➢ 6G: Highly controllable wireless channel ❑ Key enabling technology: Intelligent Reflecting Surface (IRS) AIMCOM2, ICNP, 2020 5

Hardware architecture Qingqing Wu, University of Macau What is IRS? Copper backplane Control circuit board Controllable reflection amplitude and phase shift! Smart IRS controller ： mode switching ❑ Intelligent: Reconfigurable element, software ❑ Reflecting: Passive, not active transmit/emit ❑ Surface: Massive elements, Conformal AIMCOM2, ICNP, 2020 6

Hardware architecture Qingqing Wu, University of Macau What is IRS? Copper backplane Control circuit board Controllable reflection amplitude and phase shift! Smart IRS controller ： mode switching ❑ Intelligent: Reconfigurable element, software ❑ Reflecting: Passive, not active transmit/emit ❑ Surface: Massive elements, Conformal AIMCOM2, ICNP, 2020 7

Hardware architecture Qingqing Wu, University of Macau What is IRS? Copper backplane Control circuit board Controllable reflection amplitude and phase shift! Smart IRS controller ： mode switching Energy Harvesting, Fully passive ❑ Intelligent: Reconfigurable element, software ❑ Reflecting: Passive, not active transmit/emit [S. Hu2017TSP] ❑ Surface: Massive elements, Conformal Large intelligent surface AIMCOM2, ICNP, 2020 8

Reflection model Qingqing Wu, University of Macau IRS: Reflection Model ❑ Baseband equivalent signal model at each IRS element 𝑜 = 1, … , 𝑂 : reflection amplitude where : phase shift 𝑂 : No. of elements : Absorption : Full reflection ❑ Vector form with N reflecting elements : diagonal reflecting matrix Q. Wu and R. Zhang, “ Towards Smart and Reconfigurable Environment: Intelligent Reflecting Surface Aided Wireless Networks ,” IEEE Communications Magazine, January 2020. AIMCOM2, ICNP, 2020 9

Reflection model Qingqing Wu, University of Macau Practical Model: Discrete Amplitude and Phase Shift ❑ Discrete values available at each element ❑ Uniformly quantize [0, 1] and [0, 2 π ] {0, 1} or {0.5, 1}? , ❑ Special cases: ❑ phase-shift control only: ❑ amplitude control only: Q. Wu and R. Zhang, “ Towards Smart and Reconfigurable Environment: Intelligent Reflecting Surface Aided Wireless Networks ,” IEEE Communications Magazine, January 2020. V. Arun and H. Balakrishnan, “ RFocus: Beamforming Using Thousands of Passive ,” arXiv:1905.05130, 2019. AIMCOM2, ICNP, 2020 10

Channel model Qingqing Wu, University of Macau IRS: Channel Model ❑ Baseband equivalent channel model (narrow band) complex reflection complex channel coefficient coefficients element 𝑜 𝑒 2𝑜 𝑒 1𝑜 𝑕 𝑜 ℎ 𝑜 ❑ Product-distance path loss model 𝑧 𝑦 ➢ 𝑦 : transmitted signal ➢ 𝑧 : received signal ➢ ℎ 𝑜 : first link channel ➢ g 𝑜 : second link channel Q. Wu and R. Zhang, “ Intelligent reflecting surface enhanced wireless network via joint active and passive beamforming ,” IEEE Transactions on Wireless Communications, November 2019. AIMCOM2, ICNP, 2020 11

Channel model Qingqing Wu, University of Macau IRS Path Loss Model: Product Distance or Sum Distance? ❑ Product-distance path loss model element 𝑜 𝑒 2𝑜 𝑒 1𝑜 𝑕 𝑜 ℎ 𝑜 ❑ Sum-distance path loss model 𝑧 𝑦 ✓ Applies to free-space propagation and infinitely large perfect conductor only ✓ Not applicable to IRS element-wise amplitude/phase shift control AIMCOM2, ICNP, 2020 12

IRS applications Qingqing Wu, University of Macau IRS Applications in Wireless Network ❑ IRS-enhanced coverage ❑ IRS-enhanced network throughput ❑ IRS-assisted interference cancelation ❑ IRS-aided secure communication ❑ IRS-aided SWIPT Q. Wu and R. Zhang, “ Towards Smart and Reconfigurable Environment: Intelligent Reflecting Surface Aided Wireless Networks ,” IEEE Communications Magazine, January 2020. AIMCOM2, ICNP, 2020 13

IRS applications Qingqing Wu, University of Macau IRS-enhanced Coverage ➢ Create LoS link by smart reflection to bypass obstacle ➢ Solve the “dead zone” problem in mmWave indoor coverage Prof. Erik G. Larsson: https://ma-mimo.ellintech.se/2020/01/09/intelligent-reflecting-surfaces- on-use-cases-and-path-loss-models/ AIMCOM2, ICNP, 2020 14

IRS applications Qingqing Wu, University of Macau IRS-enhanced Network Throughput ➢ A new hybrid network with active BSs/APs and passive IRSs ➢ Enhance signal power at “cell edge” or “hot spot” ➢ Boost network capacity without additional energy consumption ➢ Application scenario: eMBB for dense population areas (airport, stadium, shopping mall, etc.) Active AP/BS Passive IRS AIMCOM2, ICNP, 2020 15

IRS applications Qingqing Wu, University of Macau IRS-assisted Interference Cancelation ➢ Improve cell-edge user’s SINR by enhancing desired signal and suppressing interference at the same time ➢ Create a “signal hotspot” and “interference - free zone” in the vicinity of IRS Conventional Scheme: Coordination, low frequency factor AIMCOM2, ICNP, 2020 16

IRS applications Qingqing Wu, University of Macau IRS-aided Secure Communication Legitimate user 2 Eavesdropper Legitimate user 1 ➢ Enhance physical layer security by canceling the signal at Eve receiver AIMCOM2, ICNP, 2020 17

IRS applications Qingqing Wu, University of Macau IRS-aided SWIPT Power transfer Power transfer Information Transmission ➢ SWIPT: Simultaneous Wireless Information Power Transfer ➢ Performance bottleneck in SWIPT: Low energy efficiency of wireless power transfer (WPT) over long distance ➢ Enhance the WPT efficiency by creating an IRS-aided charging zone ➢ Application scenario: smart home/office, smart warehouse, and so on AIMCOM2, ICNP, 2020 18

IRS applications Qingqing Wu, University of Macau Smart Radio Environment achieved by IRS Scenarios: Indoor, outdoor Making Our Infrastructure Intelligent for 6G Communications! Q. Wu, S. Zhang, B. Zheng, C. You, and R. Zhang, “ Intelligent reflecting surface aided wireless communications: A tutorial ,” submitted to IEEE Trans. on Commun., Invited Paper, available on arXiv AIMCOM2, ICNP, 2020 19

IRS applications Qingqing Wu, University of Macau Industry Initiatives New startups ➢ Metawave Automotive radar, 5G wireless and AI, 28 GHz-band active repeaters (TURBO) and passive relays (ECHO) ➢ Greenerwave 4D imaging radar, millimeter wave 5G to broadband satellite communications, IoT solutions and RFID ➢ Pivotal Commware 5G mmWave technologies, systems and applications using holographic beam forming AIMCOM2, ICNP, 2020 20

IRS applications Qingqing Wu, University of Macau Industry Initiatives Q. Wu, S. Zhang, B. Zheng, C. You, and R. Zhang, “ Intelligent reflecting surface aided wireless communications: A tutorial ,” submitted to IEEE Trans. on Commun., Invited Paper, available on arXiv AIMCOM2, ICNP, 2020 21

IRS applications Qingqing Wu, University of Macau ❑ 6G White paper, published online in June 2020 6G White Paper Author Distribution: Finland, Sweden, China, USA, Australia, Germany, UK, France, … Nov. 4, 2020: 6G Research Visions Webinar Series: Deep Dive into the White Paper on Broadband Connectivity in 6G AIMCOM2, ICNP, 2020 22

Comparison with existing technologies Qingqing Wu, University of Macau IRS vs Massive MIMO/Large Intelligent Surface (LIS) IRS Massive MIMO IRS-aided Small MIMO (Non-scalable with increased frequency) (Scalable at any frequency) ➢ Need large # of RF chains due to large # ➢ No RF chains needed for IRS due of active elements to passive reflection only ➢ Increased energy consumption, hardware ➢ Low energy consumption and cost, and processing complexity at higher scalable cost frequencies (e.g., mmWave) ➢ Compatible with cellular/WiFi and can be densely deployed AIMCOM2, ICNP, 2020 23