Abstract

First responders operate in very challenging environments where access to the communications network infrastructure may be limited or even non-existent.  Device-to-Device (D2D) communications are essential for first responders to help them remain connected.  Users with D2D-enabled devices will be able to discover and communicate directly with each other without sending traffic through a base station.  This seminar presents some of the challenges and performance characteristics of D2D communications in Long Term Evolution (LTE) networks, called Proximity Services (ProSe).  The focus of this talk is on out-of-coverage device discovery, which allows devices to autonomously discover the identity of other devices and the services that they support.  The first half of the talk will describe the discovery mechanism and our work to optimize its performance, and the second half will discuss an algorithm that we developed that will let D2D devices tune their discovery function in response to information that they receive about their environment, such as the number of neighboring D2D devices. 

Biography

David Griffith is a member of the Wireless Networks Division in the Communications Technology Laboratory (CTL) at the National Institute of Standards and Technology (NIST).  His research focus is on developing mathematical models for future wireless communications systems, including analyzing control processes for Device-to-Device (D2D) communications.  He also has supported NIST’s research on wireless communications for the Smart Grid, and has modeled architectures for optical networks that aimed to improve the reliability of data flows over large backbone links.  His prior experience includes systems engineering and performance modeling for satellite communications networks for a number of companies.  He earned the PhD in electrical engineering at the University of Delaware, where his work focused on adaptive non-linear signal processing techniques, such as developing time-frequency representations for signals corrupted by impulsive noise.