Lloyd Welch, an esteemed mathematician and electrical engineer, whose research career has had a profound impact on digital communications, coding theory, and signal processing, passed away on December 28, 2023, at the age of 96.
His seminal research contributions include the celebrated Baum-Welch algorithm that is used to find unknown parameters of a hidden Markov model, and which has found widespread application in many fields including speech processing, cryptanalysis, and bioinformatics; the Berlekamp-Welch algorithm used to efficiently decode Reed-Solomon codes; the McEliece-Rodemich-Rumsey-Welch best asymptotic upper bound on the rate of a binary code; the Welch lower bound on the maximum cross-correlation of signals; and the family of Gordon-Mills-Welch sequences having ideal autocorrelation and large linear span.
Dr. Welch worked at the Jet Propulsion Lab, the Institute for Defense Analysis, and as a professor at the USC Ming Hsieh Department of Electrical and Computer Engineering. He was named an Â鶹´«Ã½AV Fellow, elected to the National Academy of Engineering, and was awarded the 2003 Claude E. Shannon Award.
