Blind Carbon Copy on Dirty Paper: Seamless Spectrum Underlay made Practical

From smart homes to smart cars and highways, and from smart health to precision agriculture, emerging technologies will soon demand ubiquitous connectivity for billions of wireless devices. The demand for more spectrum has finally started to outweigh resistance to spectrum reuse. There is currently strong impetus for introducing innovative spectrum sharing modalities that enable improved spectrum utilization and seamless cohabitation, without requiring tight coordination across legacy, scientific, government, military, and commercial users.

Spectrum underlay is a promising paradigm towards this end. It provisions secondary transmissions that operate without disturbing the primary user. Practical means of accomplishing this without requiring tight coordination between the primary and the secondary system have remained elusive, however.

This project develops practical spectrum underlay solutions which enable reliable secondary communication in scenarios where this would otherwise seem untenable: without primary-secondary coordination or channel state information, under potentially strong and time-varying interference from the primary system. The scope of potential applications includes Internet of Things (IoT), vehicular, and local area (e.g., WiFi) networks in congested spectrum areas.

Ensuring United States leadership in spectrum research, technologies, and commercial/scientific applications requires investments in spectrum sharing innovations and developing a well-educated and diverse spectrum workforce. This projects makes contributions towards both of these goals. The proposed research builds upon the principal investigator's prior work on statistical signal processing, machine learning, and matrix theory, as well as practical communications engineering -- an ideal combination to educate and engage diverse graduate and undergraduate students on the board and in the lab.

The research will develop state-of-the-art theory and engineering solutions geared towards practical implementation. The scope of the work includes the following synergistic components, organized in five thrusts: T1) Incorporating finite alphabet and error control coding constraints into the basic algebraic framework. T2) Developing multi-access and random interleaving solutions to ``orthogonalize'' multiple secondary transmissions in multiuser settings.

T3) Analyzing performance under fading scenarios, with adaptive modulation and coding. T4) Addressing key engineering issues, namely, secondary user synchronization and analog-to-digital conversion, which are challenging when the secondary signal is much weaker than the interfering primary signal. T5) Developing a software radio testbed and conducting experiments to validate the proposed solutions.

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.