Collaborative Research: CCSS: Towards Energy-Efficient Millimeter Wave Wireless Networks: A Unified Systems and Circuits Framework

Wireless communications has had a major impact on a diverse range of areas such as economy, education, health, entertainment, logistics, and travel. In order to satisfy the ever-growing demand for higher data-rates and bandwidth, the fifth generation (5G) of wireless networks envisions communication in a spectrum which includes frequencies above 6 GHz and especially the millimeter wave (mm-wave) bands. The application of high carrier frequencies in mm-wave systems allows for larger channel bandwidths compared to the current RF (radio frequency) systems which operate in lower frequency bands. However, the energy consumption of constituent circuit and system components such as analog to digital converters (ADCs) and digital to analog converters (DACs) increases significantly with bandwidth. The massive number of transceiver antennas and large bandwidth lead to substantial ADC/DAC energy consumption in mm-wave multiple-input multiple-output (MIMO) systems which is inconsistent with the limited energy budget in mobile devices and small-cell access points. This points to an urgent need for energy-aware solutions to mm-wave transceiver design. The project addresses these challenges by proposing novel transceiver architectures, circuit blocks and design techniques, and associated communication strategies. The project will tightly integrate research with a significant education and outreach program consisting of two focus areas: (i) Student training, and (ii) Disseminating research outcomes in the forms of new curricular development and student involvement. A concerted effort will be made to broaden the participation of women and students from under-represented communities in the project. The project investigates the use of nonlinear analog operators and delay elements to mitigate the coarse quantization rate-loss in mm-wave communication systems, and develops an interdisciplinary framework for investigating the theory and practice of energy-efficient mm-wave communication through three interrelated thrusts. The first thrust develops the theoretical techniques necessary to study the fundamental limits of communication, such as achievable rates, in MIMO systems with low resolution ADC/DACs and nonlinear analog processing at the transceivers. The second thrust focuses on energy-efficient circuit design and on-chip implementation of nonlinear analog components and delay elements of Thrust 1. In particular, the Volterra-Weiner series representation of transistor nonlinearity is used to design nonlinear analog operators and analyze their performance. The third thrust reconciles the practical limitations of circuitry developed in Thrust 2, with the assumptions made in the theoretical derivations in Thrust 1, and proposes practical, implementable communication protocols for mm-wave communications. This includes the design of channel estimation, multiuser scheduling, and ADC allocation mechanisms for the proposed communication systems. The proposed research effort leads to a unified framework to study the circuit design and implementation of mm-wave transceivers, along with multiuser beamforming, scheduling, and data transmission mechanisms matched with the transceiver circuit design. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.