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The Joint Wireless @ Virginia Tech and BWAC Radio Waves Fall Newsletter, 2017

In the News!

Welcome to the Wireless @ Virginia Tech fall newsletter for 2017. In a continuing effort to streamline the news and make it easier to read, we have provided you with an easy to use index below.
Mohammed
Symposium News!

We will be having our annual symposium in the spring of 2018. We are still in the planning stage so stay tuned to our website and our LinkedIn group page for more details. If you are not a member of our LinkedIn group page, now is a great time to join!

New Faculty! Dr. Lingjia Liu

Wireless @ Virginia Tech welcomes new faculty member, Dr. Lingjia Liu. Read all about our newest member at ECE News!

Saad
Dr. Walid Saad Promoted to Associate Professor

Dr. Walid Saad has been promoted to Associate Professor with tenure by the Virginia Tech Board of Visitors.

Park
New Affiliate!

Wireless @ Virginia Tech welcomes its newest member of the Industrial Affiliate's Program, Analog Devices, Inc.

Park
New Location

Jerry Park has relocated to the Virginia Tech Research Center in Arlington, VA. His new address and phone number is located on the faculty page of the Wireless @ Virginia Tech website. Dr. Park's email will remain the same.

Mohammed
Good Luck, Mohammed!

Congratulations to post-doc Mohammed J. Abdel-Rahman on his new position as professor at Al Hussein Technical University in Amman, Jordan. Al Hussein Technical University is a new university founded by the Crown Prince Foundation that aims to support Jordanian youth’s pursuit of vocational, technical and applied education.

Mohammed
Demos!

Shem Kikamaze, an M.S. student advised by Dr. Carl Dietrich, gave a demonstration, “Spectrum Access System on Cognitive Radio Network Testbed,” on October 20 at the ACM WINTECH 2017 workshop, collocated with ACM MobiCom 2017 in Snowbird, Utah.

Mohammed
Tutorials and Podcasts

Recently, students have delivered tutorials at various conferences. Shem Kikamaze, Xavier Gomez, and Dimitri DeSources, (advisor - Dr. Carl Dietrich) are delivering tutorials at WINNFORUM, November 16 - 17, 2017 and previously delivered tutorials to SPAWAR Atlantic in Charleston, SC.

Dr. Jeff Reed and Dr. Nishith Tripathi, of Award Solutions, presented a tutorial for EE Times. and will be hosting a series of podcasts in the coming weeks on topics relevant to wireless technology and communications.

Mohammed
New Project Websites!

Interested in following one of Wireless @ Virginia Tech's projects? Here are some links to our newest project websites. Papers and research findings are posted here on a regular basis.

 

EARS: Towards Harmonious Coexistence

EARS: Automated Enforcement

NeTS: Implications of Receiver RF Front End NonLinearity

Mohammed
Venture Capital Funding

Federated Wireless, Inc., a Virginia Tech spin-off company, has raised $42 million dollars in venture capital funding to revolutionize spectrum sharing and reduce the costs of delivering wireless service. Wireless faculty members Dr. Jeff Reed, Charles Clancy, Robert McGwier and Joe Mitola (Hume Center of Virginia Tech) are the founding members of Federated Wireless. Read more at Business Wire.

Buehrer
IEEE Fellow

R. Michael Buehrer, Professor and Director of Wireless @ Virginia Tech is being recognized for his contributions to wideband signal processing in communications and geolocation. More specifically, his hard work had a direct impact on Second and Third Generation (2G and 3G) cellular phone systems during a critical time in the development of that technology. He is also an active participant and organizer of IEEE conferences and workshops and has served as an editor for several IEEE journals. Read more here.

Park
IEEE Fellow

Jung-Min "Jerry" Park  is being recognized for his contributions to dynamic spectrum sharing, cognitive radio networks, and security issues. He is currently the Site Director of a National Science Foundation (NSF) Industry-University Cooperative Research Center (I-UCRC) called Broadband Wireless Access & Applications Center (BWAC). Park is also an Executive Committee Member of the National Spectrum Consortium. He is currently serving on the editorial boards of the IEEE Transactions on Wireless Communications and the IEEE KICS Journal of Communications and Networks. Read more here.  

Park
Outstanding New Professor

Dr. Harpreet Dhillon was awarded the Outstanding New Assistant Professor Award by the Virginia Tech College of Engineering in May, 2017.

Park
Torgersen Graduate Student Research Award

The College of Engineering's Paul E. Torgersen Graduate Student Research Excellence Award recognizes the top research performed by graduating masters and doctoral students across all engineering departments. Ph.D. candidate Jeffrey D. Poston received this award for his research entitled "I LoViT: Indoor Localization via Vibration Tracking. Jeffrey's advisor is Dr. R. Michael Buehrer.  

Junsung Choi
Congratulations, Junsung Choi!

Junsung Choi has passed his preliminary examination and is now a Ph.D. candidate. A letter that reports on some of Mr. Choi’s research related to intelligent transportation systems has been accepted for publication pending minor revisions.

Congratulations, Jennifer Dsouza!

Jennifer Dsouza has received her masters' degree for her thesis Analysis of RF Front-End Non-linearity on Symbol Error Rate in the Presence of M-PSK Blocking Signals, available here. Jennifer is currently employed by QualComm in San Diego.

El-Rahi
Congratulations, George!

Georges El Rahi defended his MS thesis entitled "Demand-Side Energy Management in the Smart Grid: Games and Prospects" in May 2017. He started his first job in engineering design in Washington DC.

Swarmy
Congratulations to Durga "Swamy" Inti!

Durga Laxmi Narayana Swamy Inti successfully defended his thesis "Time-Varying Frequency Selective IQ Imbalance Estimation and Compensation" in May, 2017. Swamy is currently employed as an engineer at Apple Wireless Division, Cupertino, CA.

Kim
Congratulations Dr. Kim!

Seungmo "Mo" Kim successfully defended his dissertation "Coexistence of wireless systems for spectrum sharing" this past summer. Mo has joined the Department of Electrical Engineering at Georgia Southern University as an assistant professor.

Said
Congratulations, Dr. Said!

Karim Abdel Fatah Said successfully defended his dissertation "Prolate Spheroidal Sequence Based Transceivers for Time-Frequency Dispersive Channels" in May, 2017. Dr. Said is currently an Assistant Professor at Mansoura University in Egypt.

Semiari
Congratulations, Dr. Semiari!

Omid Semiari successfully defended his PhD "Context-Aware Resource Management and Performance Analysis of Millimeter Wave and Sub-6 GHz Wireless Networks" dissertation in June, 2017 and joined the Electrical Engineering Department of Georgia Southern University as tenure-track Assistant Professor.

Sohul
Congratulations, Dr. Sohul!

Munawwar Sohul successfully defended his dissertation "Spectrum Opportunity Duration Assurance: A Primary-Secondary Cooperation Approach for Spectrum Sharing" which proposes a new primary-secondary cooperation framework for spectrum sharing. Dr. Sohul is currently working for Federated Wireless.

Ullah
Congratulations, Dr. Ullah!

Abid Ullah successfully defended his PhD in May, 2017. Abid is now a faculty member at a university in Pakistan..

Yao
Congratulations, Dr. Yao!

Miao Yao successfully defended his PhD "Exploiting Spatial Degrees-of-Freedom for Energy-Efficient Next Generation Cellular Systems". Dr. Yao's thesis is available here. He is currently working for Qualcomm.

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BWAC Spring Meeting!

The dates for the BWAC spring meeting have been set for April 24-25, 2018 at the University of Mississippi (Oxford, MS). Please mark your calendars.

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New Appointment for Dr. Jerry Park

Dr. Jerry Park has been appointed as a co-chair of the IEEE DySPAN's Steering Committee!

Park
New Affiliate!

BWAC welcomes its newest member of the Industrial Affiliate's Program, Analog Devices, Inc.

Fall, 2017 BWAC Meeting

The 2017 Fall BWAC (Broadband Wireless Access and Applications Center) Industrial Affiliate Board (IAB) meeting was held at the University of Notre Dame Oct. 26 - Oct. 27, 2017. The board meeting was attended by the BWAC Site Directors, IAB members, NSF program directors, and graduate students. Over the two days, attendees discussed major agenda items, which included evaluation and review of ongoing projects, proposals for new projects, facilitation of multi-site, collaborative projects, and strategies for the joint recruitment of industry affiliate members. On the first day, Prof. Nick Laneman moderated a panel on the NSF’s Platforms for Advanced Wireless Research (PAWR) program, which was followed by a discussion session in which the Site Directors and the IAB members exchanged their perspectives on large-scale wireless testbeds and experiments performed therein. The primary aim of the PAWR program is to support at-scale wireless research platforms conceived by the U.S. academic and industrial wireless research community. According to the NSF, “PAWR will enable experimental exploration of robust new wireless devices, communication techniques, networks, systems, and services that will revolutionize the nation’s wireless ecosystem, thereby enhancing broadband connectivity, leveraging the emerging Internet of Things (IoT), and sustaining US leadership and economic competitiveness for decades to come.” The spring 2018 meeting will be held at the University of Mississippi, April 24 - 25.


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United States Air Force Research Lab

Wireless @ Virginia Tech hosted the U.S. Air Force Research Lab (ARFL) on August 15, 2017.

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Samsung Research America

Wireless @ Virginia Tech hosted Dr. Charlie Zhang of Samsung Research America on November 10, 2017.

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Department of Energy

Wireless @ Virginia Tech hosted Hank Kenchington, the Undersecretary of the Department of Energy to discuss security for electrical grids.

Conferences

Upcoming | Previous

Upcoming

GLOBECOM 2017 is December 4-8, 2017 in Singapore. The following faculty and students will be presenting:

Dr. Walid Saad:

M. Chen, W. Saad, and C. Yin, "Liquid State Machine Learning for Resource Allocation in a Network of Cache-Enabled LTE-U UAVs", in Proc. of the IEEE Global Communications Conference (GLOBECOM), Next Generation Networking and Internet Symposium, Singapore, December 2017.


M. Chen, W. Saad, and C. Yin, "Resource Management for Wireless Virtual Reality: Machine Learning Meets Multi-Attribute Utility", in Proc. of the IEEE Global Communications Conference (GLOBECOM), Mobile and Wireless Networks Symposium, Singapore, December 2017.


U. Challita and W. Saad, "Network Formation in the Sky: Unmanned Aerial Vehicles for Multi-hop Wireless Backhauling", in Proc. of the IEEE Global Communications Conference (GLOBECOM), Next Generation Networking and Internet Symposium, Singapore, December 2017.


K. Hamidouche, W. Saad, and M. Debbah, "Popular Matching Games for Correlation-aware Resource Allocation in the Internet of Things", in Proc. of the IEEE Global Communications Conference (GLOBECOM), Selected Areas in Communications - Internet of Things (IoT) Track, Singapore, December 2017.


O. Semiari, W. Saad, M. Bennis, and B. Maham, "Mobility Management for Heterogeneous Networks: Leveraging Millimeter Wave for Seamless Handover", in Proc. of the IEEE Global Communications Conference (GLOBECOM), Mobile and Wireless Networks Symposium, Singapore, December 2017.


O. Semiari, W. Saad, M. Bennis, and M. Debbah, "Performance Analysis of Integrated Sub-6 GHz-Millimeter Wave Wireless Local Area Networks", in Proc. of the IEEE Global Communications Conference (GLOBECOM), Mobile and Wireless Networks Symposium, Singapore, December 2017.


M. Mozaffari, W. Saad, M. Bennis, and M. Debbah, "Performance Optimization for UAV-Enabled Wireless Communications under Flight Time Constraints", in Proc. of the IEEE Global Communications Conference (GLOBECOM), Mobile and Wireless Networks Symposium, Singapore, December 2017.


N. Sawyer, M. Naderi Soorki, W. Saad, and D. Smith, "Evolutionary Coalitional Game for Correlation-Aware Clustering in Machine-to-Machine Communications", in Proc. of the IEEE Global Communications Conference (GLOBECOM), Mobile and Wireless Networks Symposium, Singapore, December 2017.


Q. Zhang, W. Saad, M. Bennis, and M. Debbah, "Network Formation Game for Multi-Hop Wearable Communications over Millimeter Wave Frequencies", in Proc. of the IEEE Global Communications Conference (GLOBECOM), Mobile and Wireless Networks Symposium, Singapore, December 2017.


M. Naderi Soorki, M. H. Manshaei, W. Saad, H. Saidi, R. Hasibi , A. Shafieyoun, and A. Hajrasouliha, "Collaborative Real-Time Content Download Application for Wireless Device-to-Device Communications", in Proc. of the IEEE Global Communications Conference (GLOBECOM), Communications Software, Services and Multimedia Apps Symposium, Singapore, December 2017.

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Previous Conferences

Dr. Walid Saad has given several tutorials on "Wireless Communications and Networking with Unmanned Aerial Vehicles", at the following conferences:

IEEE MILCOM 2017 | IEEE PIMRC 2017 | IEEE ISCC 2017 | IEEE GLOBECOM 2016

 

Dr. Louis A. A. Beex has had 2 papers published in 2017:

  1. Juan Lopez Marcano, Martha Ann Bell, and A. A. (Louis) Beex, Classification of ADHD and Non-ADHD Subjects Using a Universal Background Model, Biomedical Signal Processing and Control, 39C (2018) pp. 204-212, DOI 10.1016/j.bspc.2017.07.023, online 30 August 2017

  2. Asmaa Etman and A. A. (Louis) Beex), The effect of pitch tracking on automatic dialect identification, International Journal of Speech Technology, September 2017, Volume 20, Issue 3, pp 629-634, DOI 10.1007/s10772-017-9434-0, 23 June 2017.

Dr. Beex also had students present the follwing papers in conferences:


  1. Durga Laxmi Narayana Swamy Inti and A. A. (Louis) Beex, Optimal Blind-Adaptive Compensator for Time-Varying Frequency Selective IQ Imbalance, 51st Annual Asilomar Conference on Signals, Systems, and Computers, Pacific Grove, California, October 29 – November 1, 2017.

  2. Joel T. Kees, Joseph M. Ernst, William C. Headley, and A. A. (Louis) Beex, Robust Blind Spectral Estimation in the Presence of Non-Gaussian Noise, MILCOM 2017, Baltimore MD, 23-25 October 2017.

  3. Karim Said and A. A. (Louis) Beex, DPS Signaling with OFDM-like Complexity and Superior SER Performance in 5G Doubly Dispersive Scenarios, IEEE Int’l Symposium on Personal, Indoor and Mobile Radio Communications, Montreal QC, 8-13 October 2017.

  4. Avik Dayal and A. A. (Louis) Beex, Doppler Warp Correction for Wideband Burst Communications, 2017 IEEE Conference on Computer Communications (INFOCOM 2017), WCNEE workshop on Wireless Communications and Networking in Extreme Environments, 1-4 May 2017, Atlanta GA, pp. 525-530.

 

Dr. R. Michael Buehrer Ph.D. students presented at:

  1. Mahi Abdelbar and Raghunandan Rao, Indoor Localization Through Trajectory Tracking Using Neural Networks, MILCOM 2017, Baltimore, MD.

    Abstract: Positioning in indoor environments is an ongoing challenging problem. Currently deployed wireless and cellular positioning techniques are optimized for outdoor operation and cannot provide highly accurate location information in indoor environments. Meanwhile, new applications and services for mobile devices, including the recent Enhanced 911 (E911), require accurate indoor location information up to the room/suite level. In this work, a new system for improving indoor localization of mobile users is presented by exploiting trajectory tracking techniques using neural networks (NNs). The motion trajectories of indoor mobile users are tracked using conventional positioning algorithms, then a NN is applied to identify the current room location of a mobile user based on the tracked motion trajectory. Simulation results show that the trajectory-based NN is able to provide indoor location information at the room level with much higher accuracy in different scenarios, with an enhancement of up to 49% in correct room identification, as compared to positioning techniques based only on a single-point location estimate. In addition, miss-classification of the NN system will result in selecting one of the immediate neighboring rooms instead with at least 30% probability. This paper is to be published in the upcoming MILCOM Conference Precedings.

 

Dr. Harpreet Dhillon was invited to speak at Huawei University Days hosted by the Futurewei R&D Center in Chicago on August 3rd and 4th. Huawei University Days is Huawei’s annual event that brings together top experts from academia to speak on advanced wireless communications topics. Dr. Dhillon gave a talk on “3GPP-inspired Stochastic Geometry Models for Cellular Networks”. More details about this work can be found on: https://arxiv.org/abs/1705.01699.

 

Dr. Harpreet Dhillon was also invited to speak in the Texas Wireless Summit organized by the Wireless Networking and Communications Group (WNCG) at the University of Texas (UT) at Austin. Dr. Dhillon spoke on the 3GPP-inspired stochastic geometry models for cellular networks that he has been building with his students at Virginia Tech. This year’s Texas Wireless Summit marked the fifteenth anniversary of WNCG. The technical session in this year’s Summit featured WNCG alumni speaking on diverse research topics. Dr. Dhillon completed his Ph.D. at in this research group in 2013. While in Austin, Dr. Dhillon also visited AT&T labs and gave a talk on his recent work on integrated access and backhaul. More details about this work can be found here: https://arxiv.org/abs/1710.06255.


Dr. Dhillon's students also presented at WCNC. The link to the students and their presentations is available here.

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Research | Student Research | Grants


Update: DARPA Challenge

A Virginia Tech team competing in the DARPA Spectrum Collaboration Challenge recently hosted the Defense Advanced Research Projects Agency (DARPA) program manager Paul Tilghman to present their work on collaborative intelligent radio network design. The purpose of the meeting was for the Virginia Tech team, Spectrum Without Borders, to update Mr. Tilghman on their recent progress.


DARPA is renowned for their futuristic competitions, such as the recent Grand Challenge for Autonomous Vehicles which made some huge strides in the autonomous vehicular technology realm, and the Robotics Challenge aimed at developing robots with enhanced capabilities. With that same spirit of innovation and technological advancements, DARPA kicked off the DARPA Spectrum Collaboration Challenge (SC2) at the start of this year. This collaborative machine-learning competition seeks to overcome spectrum scarcity in the radio frequency (RF) spectrum, addressing the very real problem of a rapid increase in wireless users and connected devices leading to spectrum access challenges and prices soaring to new highs.


This is a 3-year competition with a grand prize of $2,000,000 for the team whose radio design most reliably achieves successful communication in the presence of competing radios, and includes 30 contenders comprising 22 teams from academia as well as small and large companies and eight individuals.  Among the competitors, six teams, including Virginia Tech, were chosen to receive DARPA funding towards their research efforts.  The Virginia Tech team has members from both Wireless @ Virginia Tech  and the Hume Center for National Security and Technology.  The team is being led by Dr. R. Michael Buehrer, Director, Wireless @ Virginia Tech, and co-advised by Dr. Jeffrey H. Reed, Dr. Jung-Min “Jerry” Park, both Wireless @ Virginia Tech faculty, and Dr. Robert W. McGwier of the Hume Center for National Security and Technology. The team is divided into four sub groups, including students and faculty from across the College of Engineering:


The Cognitive Management Engine (CME) Group led by Dr. William C. Headley, and includes students Yue Xu and Jianyuan Yu. 
The Radio Environment Mapping (REM) Group is led by Dr. Vuk Marojevic and Ahmad Jauhar.
The Collaboration Group (Collab) is led by Dr. Hanif Rahbari and Taiwo Oyedare.
The Radio and Testing group is led by Daniel DePoy, Shem Kikamaze and Tahsin Mullick.


The program manager for the Virginia Tech team is Claude “Odge” Hutton of the Hume Center for National Security and Technology.
Over the past year, the VT team has built a radio system from the ground up including radio environment mapping features and collaboration protocol development. As part of the competition the various teams have an opportunity to play against each other in DARPA-organized scrimmages.  The Virginia Tech Team has taken part in four scrimmages allowing for testing and improvement of the system design paving the way through to the preliminary event. 


This material is based upon work supported by the United States Air Force  and the  Defense Advanced Research Project Agency (DARPA) under Contract No. FA8750-17C-0077.

Any opinions, findings and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the United States Air Force  and the  Defense Advanced Research Project Agency (DARPA).

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Student Research

 

Below is a list of new and current students' research projects. The advisor for these students is Dr. Jeff Reed.

 

Masters Level

Tarun Suman Cousik's research focus is radar data for coexistence experiments and indoor localization at 802.11ad.

Natalie Moore's research is in deep learning to overcome RF impairment.

Ahmad Jauhar is currently working on the DARPA spectrum challenge.

 

Ph.D. Level

Raghu Rao is researching Massive MIMO and radar interference mitigation.

Kaleb Kleine's research is on analog discrete-time FRESH filtering with applications in STAR systems.

Brian Slosman concentration is in improving GPS. Brian is also a colonel in the US Army.

Matt Carrick is researching joint waveform interference rejection mitigation.

Mina Labib is researching security issues and coexistence of LTE and radar.

Thaddeus Czauski is researching the impact of human behavior in cellular resource management.

Sahana Raghunandan is researching interference between 5G and satellite systems.

Aditya Padaki is due to defend his dissertation in December, 2017. Aditya's research is on Impact of Receiver Front-End Nonlinearity on Efficient Spectrum Access and Co-existence.

Nistha Tandiya is researching strengthening cyber resilience of internet of things using bio-inspired artificial intelligence techniques.

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Service

Dr. Lingjia Liu is serving the wireless community in the following positions:

1. Leading Co-Chair of MASSIVE MIMO/FD-MIMO IN 5G MOBILE COMMUNICATIONS in conjunction of IEEE International Symposium on Personal, Indoor and Mobile Radio Communications

2. The Publicity Co-Chair of 2017 IEEE 86th Vehicular Technology Conference, the flagship conference IEEE Vehicular Technology Society.

3.The Co-Chair of Technical Program Committee of 6th International Workshop on Emerging Technologies for 5G and Beyond Wireless and Mobile Networks (ET5GB) in conjunction with IEEE Globecom’17.

4. The Co-Chair of the Wireless Communications Symposium of IEEE ICC 2018, the flagship conference of IEEE Communication Society.

5. The Fundraising Chair of 2018 IEEE Communication Theory Workshop

 

Dr. Jerry Park has been appointed to the steering committee of IEEE International Symposium on Dynamic Spectrum Access Networks (DySPAN).

Dr. Walid Saad has been elected as the Vice-Chair of the Americas for the IEEE Communications Society (ComSoc) Technical Committee on Cognitive Networks.

Dr. Harpreet Dhillon has been appointed to editorial boards of IEEE Transactions on Green Communications and Networking and the IEEE Wireless Communications Letters. Dr. Dhillon has also been named as the TPC Track Co-chair for Track 2: MAC and Cross Layer Design, IEEE PIMRC 2017, Montreal, QC, Canada.

Dr. Jeff Reed has been appointed to the committee to evaluate wireless communicatons in smart cities by Governor Terry McAuliffe of the Commonwealth of Virginia.

 

Journal Publications


For a complete list of journal and conference proceedings publications for 2017, please visit our updated Featured Publications page! You can sort by type, and by professor.

 

Coexistence between Communication and Radar Systems - A Survey


Authors: Mina Labib, Vuk Marojevic,Anthony F. Martone, Jeffrey H. Reed, Amir I. Zaghloul


Abstract: Data traffic demand in cellular networks has been tremendously growing and has led to creating congested RF environment. Accordingly, innovative approaches for spectrum sharing have been proposed and implemented to accommodate several systems within the same frequency band. Spectrum sharing between radar and communication systems is one of the important research and development areas. In this paper, we present the fundamental spectrum sharing concepts and technologies, then we provide an updated and comprehensive survey of spectrum sharing techniques that have been developed to enable some of the wireless communication systems to coexist in the same band as radar systems. Read more.

 


Extending LTE into the Unlicensed Spectrum: Technical Analysis of the Proposed Variants


Authors: Mina Labib, Vuk Marojevic, Jeffrey H. Reed, Amir I. Zaghloul


Abstract: The commercial success of the Long Term Evolution (LTE) and the resulting growth in mobile data demand have urged cellular network operators to strive for new innovations. LTE in unlicensed spectrum has been proposed to allow cellular network operators to offload some of their data traffic by accessing the unlicensed 5 GHz frequency band. Currently, there are three proposed variants for LTE operation in the unlicensed band, namely LTE-U, Licensed Spectrum Access (LAA), and MulteFire. This paper provides a comparative analysis of these variants and explains the current regulations of the 5 GHz band in different parts of the world. We present the technical details of the three proposed versions and analyze them in terms of their operational features and coexistence capabilities to provide an R\&D perspective for their deployment and coexistence with legacy systems.

 

Adaptive Pilot Patterns for CA-OFDM Systems in Nonstationary Wireless Channels


Authors: Raghunandan M. Rao, Vuk Marojevic, Jeffrey H. Reed


Abstract: In this paper, we investigate the performance gains of adapting pilot spacing and power for Carrier Aggregation (CA)-OFDM systems in nonstationary wireless channels. In current multi-band CA-OFDM wireless networks, all component carriers use the same pilot density, which is designed for poor channel environments. This leads to unnecessary pilot overhead in good channel conditions and performance degradation in the worst channel conditions. We propose adaptation of pilot spacing and power using a codebook-based approach, where the transmitter and receiver exchange information about the fading characteristics of the channel over a short period of time, which are stored as entries in a channel profile codebook. We present a heuristic algorithm that maximizes the achievable rate by finding the optimal pilot spacing and power, from a set of candidate pilot configurations. We also analyze the computational complexity of our proposed algorithm and the feedback overhead. We describe methods to minimize the computation and feedback requirements for our algorithm in multi-band CA scenarios and present simulation results in typical terrestrial and air-to-ground/air-to-air nonstationary channels. Our results show that significant performance gains can be achieved when adopting adaptive pilot spacing and power allocation in nonstationary channels. We also discuss important practical considerations and provide guidelines to implement adaptive pilot spacing in CA-OFDM systems. Read more.

 

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Grants

Wireless @ Virginia Tech continues to produce outstanding cutting edge research funded by the following grants:

 

Dr. Lingjia Liu

 

NeTS: Small: Spatial Spectrum Sensing-Based Device -to-Device (D2D) Networks:

Abstract:

The continuing growth of mobile data applications is expected to trigger a large increase in mobile traffic over the next decade. Direct device-to-device (D2D) communications between user devices that offload cellular network traffic has a great potential to be an integral part of the solution to address this mobile data challenge. In this project, the researchers will introduce a novel spectrum access model, called sensing-based D2D communication, to significantly improve the overall network spectral-efficiency of a mobile broadband network. In sensing-based D2D, users utilize spatial spectrum sensing to explore temporal and spatial spectrum transmission opportunities within the underlying cellular network bands. Equipped with spatial spectrum sensing, these users can efficiently utilize the available non-occupied cellular spectrum while providing enough protection to legacy base-station-to-device users. This project will result in a new enabling technology for future mobile broadband networks and will also effectively enrich educational materials by providing software and hardware-based implementation and experimental activities. The grant is for $352,819.00. Read more

 

SpecEES: Collaborative Research: Enabling Spectrum and Energy-Efficient Dynamic Spectrum Access Wireless Networks using Neuromorphic Computing

Abstract:

During the last two decades, the use of Radio Frequency (RF) spectrum has increased tremendously due to the ever growing demand for wireless connectivity. The existing network technologies that support the current wireless data demand are expected to increase their capacity significantly in the next decade, calling for spectrum and energy efficient communication strategies. There are two popular approaches to efficiently utilize the RF spectrum: One is the cognitive radio networks which allow mobile users to share the spectrum that has been primarily allocated to other services such as television broadcasting, global position system (GPS), radar, weather forecasting, etc., provided that the mobile users impose limited interference to existing services. Another approach is to enhance the mobile broadband networks via expanded bandwidth, massive Multiple-Input Multiple-Output (MIMO) systems, and densified heterogeneous networks (HetNets). However, both approaches have limitations and have different impacts on spectrum efficiency and energy efficiency. In addition, current hardware platforms exhibit formidable challenges in supporting high computational complexity and low power consumption. This project introduces a novel network architecture and its application-specific hardware optimization using neuromorphic computing devices. The new wireless network architecture allows mobile users to perform spatio-temporal spectrum sensing and actively search for dynamic spectrum access (DSA) opportunities to enable short-range and local communications. Meanwhile, neuromorphic computing devices that mimic bio-neurological processes will be designed to tackle the high computational complexity of the new dynamic spectrum access approach with extremely low power consumption. In this way, we will be able to enable our nation's next-generation wireless communications and networking that are intelligent, spectrum-efficient, and energy-efficient in a dynamic spectrum environment. The developed concepts and technologies will also help achieve National Broadband Plan which targets at significant improvements in the efficiency of RF spectrum utilization. The project has an extensive education and outreach plan which includes designing new course components on energy-efficient communications, analog neuron circuits, and computational intelligence for wireless networks, joint training of graduate and undergraduate researchers between the two collaborative institutions, and outreach to telecommunication industry and underrepresented students through seminars and diversity programs. The grant is worth $700,000.00 and is a joint project between Virginia Tech and the University of Rhode Island. Read more here and here.

 

DSA Policy Program of National Spectrum Consortium

This award is $14.2 million where Virginia Tech serves as a subcontractor and the lead is LGS Innovations. Virginia Tech's share is $950K with Dr. Liu as the PI and Prof. Yang Yi (ECE at VT, MICS group) serving as the Co-PI. Virginia Tech is focusing on the optimization aspect of the DSA project.

 

Dr. Harpreet Dhillon

 

Dr. Dhillon has received the following grants:

Statistical Performance Analysis and Resource Management for Cyber-Physical Internet of Things Systems

Abstract: Realizing the vision of pervasive Internet of Things (IoT) that will endow a myriad of physical objects that include sensors, wearables, mundane objects, and connected vehicles, with cyber capabilities, is contingent upon effectively managing the interwoven synergies across its cyber and physical realms. The overarching goal of this project is to develop a novel cyber-physical system (CPS) science that can enable effective modeling, optimization, and management of the IoT as a fully-fledged CPS. Developing this science will, in turn, catalyze the deployment of the IoT and its numerous services that range from smart healthcare, to smart buildings and intelligent transportation, thus having a broad societal impact. Enabling the IoT will also expedite the transformation of cities and communities, into truly smart environments thus enhancing the quality of life of their residents. The proposed research is coupled with an educational plan that includes substantial involvement of graduate and undergraduate students in cross-cutting CPS research, as well as IoT-centric outreach activities targeted at local high school students from the under-represented groups. This synergistic integration of research and education will contribute to training a new workforce that is equipped with the necessary CPS skills needed to work in the emerging IoT domains. This grant if for $500,000.00. Read more.

 

SpecEES: Collaborative Research: Stochastic Geometry Meets Channel Measurements: Comprehensive Modeling, Analysis, Fundamental Design-tradeoffs in Real-world Massive-MIMO Networks

Abstract: One promising solution to handle the ever-increasing demand for wireless capacity is to deploy significantly higher number of antenna elements at the base station compared to the number of users in the cell. This so called Massive MIMO approach creates extra degrees of freedom that can be used to "shape" beams, thus enhancing both the energy and spectral efficiency of communication links. Massive MIMO can be implemented in a variety of ways. One extreme is the concentrated implementation in which hundreds of antennas are deployed at a single location within a cell. On the other extreme is the fully distributed implementation in which hundreds of single-antenna remote radio heads, distributed throughout the cell, are connected to a common baseband processing unit, thus forming a distributed base station. In between these extremes is the relatively less-investigated case of semi-distributed implementation in which multi-antenna remote radio heads are distributed across the cell. While the massive MIMO idea has been around for several years now, our understanding of the performance of these systems is still limited. This is mainly due to the lack of real-world propagation models (especially for the semi-distributed implementations) as well as mathematical tools that can expose performance trends for different spatial distributions of the users and base stations, both of which are known to significantly impact the performance of these systems. The main goal of this research is to develop a transformative measurements-driven analytical approach to enable the efficient deployment of massive MIMO networks ultimately leading to better customer experience, via improved spectral efficiency, and greener wireless communications, via improved energy efficiency. All the key outcomes of this project will be widely disseminated through publications, tutorials, and industry collaborations. This grant if for $354,270.00. Read more.

 

Dr. Carl B. Dietrich

 

UAS Model City for RF Experimentation

Dr. Carl Dietrich is principal investigator of a Defense University Research Infrastructure Program (DURIP) grant, with co-PIs Drs. Vuk Marojevic, Jerry Park, and Jeff Reed. The grant was for $250,000.00. Read more.

 

Dietrich is also PI on three small projects with MITRE Corp. Dietrich is leading projects related to wireless network capacity and distributed MIMO systems. Dr. Nicholas Polys, Director of Visual Computing at Virginia Tech, is co-PI on the projects and is leading the third project.

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