Wireless technology is heading for a spectrum crunch with the proliferation of data-hungry devices and applications. Millimeter-wave (mmW) technology, operating between 30GHz to 300GHz, is a promising emerging solution that offers orders-of-magnitude larger bandwidth than current systems and efficient spectrum usage through beamforming. Wireless networks will soon require aggregate data capability of tens or hundreds of Gigabits/sec (Gbps). However, the currently used wireless spectrum is limited, due to technological, physical, and regulatory constraints. This has led to new approaches for efficient use of spectrum, such as interference management, multi-antenna technology, cognitive radio, and the current approach of small cell technology to maximize the spatial reuse of limited spectrum. However, there is a growing realization that current wireless networks, operating below 6 GHz, cannot meet the growing need–there is simply not enough spectrum in existing bands.
An integrated approach is needed to address the key issues of capacity, latency, complexity, energy consumption, and scalability to realize the potential of mmW technology. We propose the study of fundamental performance limits and design strategies for mmW wireless networks spanning radio hardware, communication and signal processing, and networking protocols. The approach is based on an innovative modular concept of a slice, defined by a mmW chain consisting of power efficient wideband circuits, and representing a unit of beam-frequency PHY resource, that enables scalability and reconfigurability.
The proposed research plan integrates key elements of mmW mixed hardware development, data-converter design, beam-frequency signal processing and communication techniques, and networking protocols for optimizing performance-complexity-energy tradeoffs. The results of this ambitious interdisciplinary project will lead to a new framework for the integrated design of scalable mmW MIMO network architectures for small cell mobile access and backhaul requiring Gigabit rates and low latency.
The figure (left) illustrates a two-level network architecture that will be enabled by the proposed research. The larger triangles represent access points (APs) that form the backhaul network and the smaller triangles represent small cell APs that provide access to mobile stations (MSs). The backhaul APs form a mesh network of point-to-multipoint links that connects to small cell APs on one end and to a fiber gateway and on the other end. Transceivers with high-dimensional antennas will be used at the APs, whereas transceivers with low-dimensional (4-16) antenna arrays will be used at MSs. We primarily consider time-division duplexed communication over a 6.25GHz band with a center frequency of 68GHz, which is split into channels of 250 MHz bandwidth each.
The research spans communication theory and signal processing, mmW hardware and data converter design, networking protocols, and experimental validation with a state-of-the-art testbed. The research is anchored on four goals: 1) Development of a multi-beam MIMO network architecture and communication/signal processing techniques for mobile access; 2) Investigation of a scalable and reconfigurable slice-based mmW transceiver design for multi-beam MIMO; 3) Investigation of medium access control and higher layer protocols to address mmW propagation challenges and to fully exploit the advanced physical layer capabilities; and 4) Integrated system modeling and assessment for performance-complexity-energy optimization and experimental validation.
This project is supported by National Science Foundation award (#1705026/1703389).
- Parmeswaran Ramanathan, University of Wisconsin-Madison (Lead PI) – Networking protocols
- Akbar Sayeed, University of Wisconsin-Madison (former lead PI) – signal processing/wireless communications
- Deukhyoun Heo, Washington State University (PI) – mmWave RF front-end transceiver
- Subhanshu Gupta, Washington State University (Co-PI) – mmWave data converters
- Zongshen Wu, Ph.D. student, University of Wisconsin
- Sheikh Nijam Ali, Ph.D. student, Washington State University
- Erfan Ghaderi, Ph.D. student, Washington State University
- Qiuyan Xu, Ph.D. student, Washington State University
- Chase Puglisi, Ph.D. student, Washington State University
Chris Hall, M.S., University of Wisconsin, Graduated – Dec 2017
Yifan Zhu, M.S., University of Wisconsin, Graduated – May 2018
Goal 1: Development of a multi-beam MIMO network architecture and communication/signal processing techniques for mobile access. -
Goal 2: Investigate scalable slice-based integrated wideband architectures for mmW hardware and data-converters. Design and optimization of low-complexity energy-efficient circuits and systems for reconfigurability, channel-aggregation, and MIMO. -
Goal 3: Develop PHY-MAC and higher layer networking protocols to exploit the advanced PHY functionality of wideband multi-beam MIMO.
Goal 4: Integrated system modeling and assessment for performance-complexity-energy optimization and experimental validation. , 
- Erfan Ghaderi, Ajith S. Ramani, Arya A. Rahimi, Deuk Heo, Sudip Shekhar and Subhanshu Gupta, “A 4-Element Wide Modulated Bandwidth MIMO Receiver with >35 dB Interference Cancellation,” under review.
- Erfan Ghaderi, Ajith S. Ramani, Arya A. Rahimi, Deuk Heo, Sudip Shekhar and Subhanshu Gupta, “An Integrated Discrete-Time Delay-Compensating Technique for Large-Array Beamformers,” IEEE Trans. on Circuits and Systems – I: Regular Papers, vol. 66, no. 9, pp. 3296-3306, Sept. 2019.
- Zhu, C. Hall, and A. Sayeed, I-Q Mismatch Estimation and Compensation in Millimeter-Wave Wireless Systems,2018 Global Symposium on Millimeter-Waves, May 22-24, 2018, Boulder, CO.
- Sayeed, C. Hall and Y. Zhu, A Lens Array Multi-beam MIMO Testbed for Real-Time mmWave Communication and Sensing,invited paper, First ACM mmNets workshop, Snowbird, UT, October 16, 2017.
- Sayeed, Millimeter-Wave Wireless: A Cross-Disciplinary View of Research and Technology Development,invited talk, First ACM mmNets workshop, Snowbird, UT, October 16, 2017.
- Sayeed, Multi-Aperture Phased Arrays Versus Multi-beam Lens Arrays for Millimeter-Wave Multiuser MIMO, Asilomar, CA, Oct. 31, 2017.slides. Copyright 2017 SS&C. Published in the Proceedings of the Asilomar Conference on Signals, Systems and Computers, Oct 29-Nov 1, 2017, Pacific Grove, CA.
- Gao, L. Dai, A. Sayeed, Low RF-Complexity Technologies for 5G Millimeter-Wave MIMO Systems with Large Antenna Arrays, IEEE Communications Magazine, February 2018.
- Gao, L. Dai, S. Zhou, A. Sayeed, and L. Hanzo,Beamspace Channel Estimation for Wideband Millimeter-Wave MIMO with Lens Antenna Array, IEEE ICC, May 20-24, 2018, Kansas City, MO.
- P. Agarwal, J. H. Kim, P. P. Pande, D. Heo, “Zero-Power Feed-Forward Spur Cancelation for Supply-Regulated CMOS Ring PLLs,”IEEE Transactions on Very Large Scale Integration (VLSI) Systems, vol. 26, no. 4, pp. 653-662, April 2018.
- S. N. Ali, P. Agarwal, J. Baylon, S. Gopal, L. Renaud, L. and D. Heo, “A 28GHz 41%-PAE linear CMOS power amplifier using a transformer-based AM-PM distortion-correction technique for 5G phased arrays,” IEEE International Solid – State Circuits Conference, San Francisco, CA, 2018, pp. 406-408.
- S. N. Ali, T. Johnson, D. Heo, “DC Polarity Control in Radio Frequency Synchronous Rectifier Circuits,” IEEE Microwave and Wireless Components Letters, vol. 27, no. 12, pp. 1107-1109, Dec. 2017.