Research

Research Interests

Dr. Mitchell received the National Science Foundation CAREER award in 2022 — NSF's most prestigious award for early-career faculty — and the 2019 NMSU Early Career Award for Exceptional Achievements in Creative Scholarly Activity. He has received four best paper awards and is the recipient of the 2019 New Mexico EPSCoR Mentor Award. He currently holds the IFT Professorship in Telecommunications at New Mexico State University.

Digital Communications Information Theory Data Compression Coding Theory and Practice Machine Learning Circuit Design Quantum Error Correction Post-Quantum Cryptography

Current Research Projects

CCF-2145917 · National Science Foundation · Principal Investigator · 02/2022 – 01/2027

CAREER: Sparse Graph-Based Codes for Network Data Compression

SCALE W52P1J-22-9-3009 · Department of War (NMSU sub-award) · Co-Principal Investigator · 04/2024 – 03/2027

Radiation-Hardened Microelectronics Workforce Development Consortium

Previous Research Projects (5)
CNS-2148358 · National Science Foundation · Co-Principal Investigator · 05/2022 – 04/2026

RINGS: Resilient Edge Ecosystem for Collaborative and Trustworthy Disaster Response

HRD-1914635 · National Science Foundation · Co-Principal Investigator · 02/2020 – 01/2026

CREST: Interdisciplinary Center for Research Excellence in Design of Intelligent Technologies for Smartgrids Phase II

OIA-1757207 · National Science Foundation · Senior Personnel · 09/2018 – 08/2024

RII Track-1: The New Mexico SMART Grid Center: Sustainable, Modular, Adaptive, Resilient, and Transactive

CCSS-1710920 · National Science Foundation · Principal Investigator · 09/2017 – 08/2020

CCSS: Coding for 5G and Beyond: Limits and Efficient Algorithms

NNX15AL51H · National Aeronautics and Space Administration · Principal Investigator · 09/2017 – 09/2018

Hybrid UWB/Optical Communications for Distributed Space Systems

Project Highlights

Quantum Error Correction

Quantum computers promise to solve certain problems far faster than any supercomputer, but the fragile quantum states they rely on are easily disturbed by noise. Small errors build up quickly and can derail a computation entirely. This project develops new quantum error correcting codes and better decoding algorithms so that quantum computers can keep working reliably even as they scale up.

Impact

The group's quantum LDPC and quantum convolutional code designs, along with new decoding techniques including soft-hard decimation and reinforcement-learning-based decoders, outperform existing decoders across a range of noise levels, moving quantum hardware closer to reliable, fault tolerant operation.

Selected publications

Coded Discrete Variational Autoencoders (Coded-DVAEs)

AI tools that generate text, images, or audio, like large language models and diffusion based art generators, are usually overconfident: they report high certainty in their outputs even when they're wrong. This project asks whether ideas from error correcting codes, the same math used to keep data reliable on hard drives and over wireless links, can make these generative AI models both better at their core task and more honest about what they don't know.

Impact

Building redundancy borrowed from coding theory into a generative model's internal representation improved both the quality of its generated output and, critically, gave uncertainty estimates that better reflect the model's actual confidence, a step toward AI systems that know, and can communicate, the limits of what they know.

Selected publications

Machine Learning Techniques for 6G Communication Systems

Future 6G wireless networks will need extremely fast, extremely reliable communication for things like remote surgery and autonomous vehicles. This project uses reinforcement learning to speed up the decoders that correct transmission errors, teaching them to process the right pieces of data in the right order rather than a fixed sequence. It also looks at how machine learning models running on connected devices can be trained to tolerate noisy, error prone wireless links directly, instead of relying only on traditional error correction hardware.

Impact

The reinforcement learning approach sped up decoder convergence by 30 to 50 percent, directly cutting latency and power use in next generation wireless hardware. The companion technique for training AI models to tolerate channel noise cut power consumption by roughly 30 percent in IoT systems, an important gain for battery powered sensors and devices.

Selected publications

Spatially Coupled LDPC (SC-LDPC) Codes

Many modern error correcting codes trade off between decoding easily and getting close to the theoretical performance limit. This project showed that chaining together many small, identical coding structures into one long connected code, called spatial coupling, lets simple iterative decoders reach performance very close to that theoretical limit. The resulting codes also correct errors in a distinctive wave like pattern, with reliability spreading in from the ends of the chain toward the center as the decoder runs.

Impact

This work established spatially coupled codes as a practical way to get near optimal performance with low complexity decoding, and the approach has since been adopted well beyond communications, including in compressed sensing, quantum codes, and statistical physics.

Selected publications

Lossy Source Coding

Compressing speech, audio, and video always involves some loss of information, and the goal is to lose as little quality as possible for a given amount of compression. This project applies spatially coupled coding structures, originally developed for correcting transmission errors, to the compression problem itself, showing that these codes can compress data almost as efficiently as the theoretical best possible, with practical encoding delay.

Impact

The resulting codes close much of the gap to the theoretical compression limit and outperform existing joint source and channel coding schemes with comparable complexity and delay, useful wherever data must be both compressed and protected against transmission errors.

Selected publications

Generalized Codes for Ultra-reliable Low-Latency Communication

5G and future wireless networks need to support use cases, like industrial automation and vehicle to vehicle safety systems, that demand both very low error rates and very low delay. This project designs generalized low density parity check codes, which replace simple parity checks with stronger error correcting building blocks, tailored specifically for these ultra reliable, low latency requirements.

Impact

The resulting codes outperform a range of state of the art alternatives at the block lengths and code rates relevant to 5G URLLC, giving network designers a practical path to meeting these strict reliability and latency targets.

Selected publications

Low-Complexity Hardware Implementation of Codes

Turning an error correcting code into a real chip requires simplifying the math so it can run with limited hardware precision, without giving up too much performance. This project develops quasi cyclic LDPC codes that are easy to encode with simple shift register circuits, along with analysis tools that predict how a decoder will behave once its internal messages are rounded to a fixed number of bits. The group also builds and tests real decoder and encoder hardware, including circuits tuned for medical applications like heart rhythm monitoring.

Impact

This work produced performance bounds and design techniques now used to build efficient, low power LDPC hardware, plus a wearable sensor decoder that keeps over 99 percent classification accuracy even when a fifth of the incoming sensor data is corrupted.

Selected publications

Robust Error Control for Time-Varying Channels

Wireless and other communication links do not stay the same quality over time, so a single fixed error correcting code is rarely the best choice throughout a connection. This project studies puncturing, a technique that lets one code adapt to multiple transmission rates by selectively withholding some coded symbols, and works out exactly what makes a code well suited to this kind of adaptation.

Impact

The group derived a simple mathematical rule that predicts how well an LDPC code will perform after puncturing, and used it to design codes that stay reliable across a wide range of rates, useful for links where channel quality changes during a single connection.

Selected publications

High-rate Coupled Turbo/LDPC Codes for Optical/Streaming Applications

High speed optical networks need error correcting codes that run at very high code rates with hardware efficient decoding. This project studies braided convolutional codes, a family related to turbo codes where two encoders feed outputs into each other over time, and shows they perform well even close to the noise floor while tolerating the kind of rate adjustment optical systems need.

Impact

These braided codes match or beat other high rate code families proposed for optical communication while reusing decoding hardware similar to turbo codes, making them a practical option for next generation high speed optical links.

Selected publications

Acknowledgements

The research described above is based upon work supported in part by the National Science Foundation under Grant Nos. CCF-2145917, CCSS-1710920, CCF-1161754, OIA-1757207, and HRD-1914635, and in part by the National Aeronautics and Space Administration (NASA) Training Grant NNX15AL51H.