“Propagation Issues for Cognitive Radio” by Andreas F. Molisch, Larry J. Greenstein, and Mansoor Shafi, provides valuable information critical to the success of cognitive radio (CR), an important developing area of wireless communications. The paper, which appeared in the May 2009 issue of the Proceedings of the IEEE (vol. 97, no. 5, pp. 787-804), covers the essentials of wireless propagation issues in a format suitable for CR researchers, providing access to information limited previously to propagation researchers. CR aims to improve spectral efficiency of licensed communications frequencies by using unlicensed radios that can recognize usage or nonusage at a given frequency and be allowed to transmit at that frequency during intervals of nonusage. The paper gains its accessibility through extensive use of intuitive descriptions and analogies, using equations sparingly but maintaining a rigorous presentation. Its importance lies in its ability to enable CR researchers to choose good channel models, which is key to demonstrating low interference of the radios to primary spectrum users.
An IEEE Fellow, Dr. Shafi is currently a Telecom Fellow (Wireless) with Telecom New Zealand in Wellington, where he advises on future directions of wireless technologies and standards. He represents the New Zealand government in the meetings of the World Radio Conference and in the meetings of ITU and APT relating to wireless and spectrum standards.