Contributions by the GTPG began with a revamped fundamental theory of small-scale fading in radio systems. As cellular communications exploded in the 1990s, engineering mobile radio links in fading channels was still built upon a 1960s understanding of radio wave propagation, developed by Bell Labs pioneers such as Clarke, Gans, and Jakes. However, with the proliferation of wireless communications into more varied environments, the emerging use of antenna arrays, and the advent of multiple-input, multiple-output (MIMO) systems, th 1990s understanding of small-scale fading processes and channel modeling needed significant revision and improvement.
Prof. Durgin invented a new type of probability density function – the Two-Wave with Diffuse Power (TWDP) distribution – to describe the general physics of multipath fading in RF systems. Durgin, Rappaport, and de Wolf’s 2002 IEEE Transactions on Communications journal article, “New analytical models and probability density functions for fading in wireless communications”, provided the original formulation of this distribution and the common K-Delta parameterization used by engineers today. This work was revolutionary because it captured physically realistic scenarios that produced Hyper-Rayleigh fading (or “worse-than-Rayleigh” fading statistics). As such, numerous researchers around the world now benchmark the performance of radio systems against TWDP channel models. The concept of TWDP fading invented by Durgin has been mainstreamed into modern research, as demonstrated by this Google Scholar search on the term “TWDP fading”.
Concurrently with the TWDP fading formulation, Prof. Durgin also invented multipath shape factors, afundamental relationship between the direction-of-arrivals of radio power and the statistics of fading radios. Published in the 2000 IEEE Transactions on Antennas and Propagation article “Theory of multipath shape factors for small-scale fading wireless channels”, this fundamental physical relationship has become a popular tool for both educators and researchers that study the radio channel. Much of this early work in channel modeling was incorporated into the book Space-Time Channel Modeling. Published in 2002, this work was the first text in its field to deal with emerging technologies of broadband and multiple input, multiple output (MIMO) radio systems.
In a 2008 Transactions on Antennas and Propagation article, along with researcher Joshua Griffin, Prof. Durgin also developed a family of new fading distributions for backscatter radio systems – particularly those involving multiple antennas. This work of fundamental physics has spawned a new generation of multi-antenna research in backscatter radio applications.
Active areas of backscatter radio research in the group include:
- theory and practice of RF channel modeling and measurement
- backscatter channel modeling
- self-tuning, large-scale propagation models
- electromagnetic theory applied to RF modeling
- measurement and modeling in extreme environments