After an introduction to radiomobile and radio systems deployed in the access network, the book describes cognitive radio concepts and capabilities, which are the basis for reconfigurable radio systems. The self-organizing network features introduced in 3GPP standards are discussed and before IEEE 802.22, the first standard based on cognitive radio, is described. Then the ETSI reconfigurable radio systems functional architecture and the IEEE 1900.4 standard for reconfigurable radio are examined. Finally, the author presents new scenarios and future visions that reconfigurable radio systems may bring.