Yoshihisa Okumura (Japanese: 奥村善久; 2 July 1926 – 18 February 2023) was a Japanese engineer, known for development of cellular telephone networks. His radio survey of signal strength as a function of distance as measured in drive tests in automobiles was critical to the system planning of mobile radio telephone systems.
Source: “Yoshihisa Okumura”, English Wikipedia (CC BY-SA 4.0), excerpt