David Griffith Email & Phone Number

Gaithersburg, Md, Us

I lead a team of scientists and engineers working on two major projects to develop measurement tools and data sets to support the next generation of wireless communications systems. Our research in channel measurement and modeling (CMM) at millimeter wave frequencies (28 GHz, 60 GHz, and 140 GHz) helps develop quasi-deterministic (Q-D) channel models for a variety of indoor and outdoor deployment scenarios. We sponsor the NextG Channel Model Alliance (https://nextg.nist.gov/), which maintains a large and growing millimeter wave channel data database. In 2025, we will collect channel measurement data in Frequency Range 3 (FR3), the band of frequencies from 7.125 GHz to 24.25 GHz, which is of interest to manufacturers and service providers as a good candidate to support next-generation wireless systems.Our recent work on incorporating sensing functions into next-generation communications systems analyzed the performance of the IEEE 802.11bf Wi-Fi standard. Our new work focuses on cellular standards and includes a collaboration with the Alliance for Telecommunications Industry Solutions (ATIS) Joint Communications and Sensing (JCAS) subgroup, which published its Phase I report, "Channel Measurements and Modeling for Joint/Integrated Communication and Sensing, as well as 7-24 GHz Communication" in July 2024. (Link: https://nextgalliance.org/white_papers/channel-measurements-and-modeling-for-joint-integrated-communication-and-sensing-as-well-as-7-24-ghz-communication/)

I was detailed to NIST's Program Coordination Office (PCO), where I assisted with the preparation and planning of the NIST budget for the upcoming fiscal year. I provided technical content for briefing memos for senior NIST leadership to aid them in preparing for meetings with heads of other federal agencies, members of Congress, and leaders in academia and industry. I supported NIST leadership offsite meetings and provided technical content for briefings by NIST leadership to NIST's Visiting Committee on Advanced Technology (VCAT). I also chaired NIST's Colloquium Organizing Board and helped transition from the virtual colloquium presentations necessitated by the COVID-19 pandemic back to in-person and hybrid presentations. NIST colloquium talks deal with a variety of timely science/engineering subjects at a level that is accessible to non-specialists, and videos of the talks are available here: https://www.nist.gov/video-category/nist-colloquium-series

I led a team of four engineers working on a variety of projects in the Wireless Networks Division in CTL. Their work ranged from supporting the rollout of broadband communications for first responders via FirstNet to working on the National Advanced Spectrum and Communications Test Network (NASCTN), which allows commercial wireless operators to use the federally owned bands around 3.5 GHz when they are idle.My duties included regular meetings with the team members to discuss progress and help them get the resources they needed to complete their work, and helping them to develop project and performance plans.

When I started working at NIST in 1999 in the Information Technology Laboratory (ITL), I researched advanced optical network architectures that partitioned data traffic by using different wavelengths of light to carry various information streams. My work focused on optical network resiliency, including how to allocate wavelengths to create backup paths. This work included all-optical switches; instead of converting optically encoded data transmissions into electrical form to switch it from one location to another, these switches route the light waves themselves.Around 2006, I transitioned to research on wireless communications. My first area of focus was the "smart grid," a newer iteration of the power infrastructure that incorporates better information processing, new types of energy sources, and greater resiliency. I examined issues such as how to simulate the interactions between the electrical distribution network and the communications network that has to transport information about the distribution network's performance.Starting around 2012, my work shifted to public safety communications networks, with an emphasis on device-to-device communications, including performance modeling of control and communications channels for performance optimization and the use of statistical models and reinforcement learning (RL) training for controllers to allocate spectrum resources to co-existing Radio Access Networks (RANs). RL is a type of artificial intelligence algorithm that can be trained to respond to changes in its environment. RL is probably best known for achieving feats like beating human chess and go players, but it is also used in a lot of engineering applications like control systems.My current research involves incorporating radar-like sensing functions into communications networks.