Open Radio Access Network (O-RAN) Systems Architecture and Design, 2nd edition, gives a jump start to engineers developing O-RAN hardware and software systems, providing a top-down approach to O-RAN systems design from an author with a silicon, software, and system background. It gives an introduction into why wireless systems look the way they do today before introducing relevant O-RAN and 3GPP standards. The remainder of the book discusses hardware and software aspects of O-RAN system design, including dimensioning and performance targets, and some practical use case examples that include 5G advanced topics. This edition includes comprehensive updates in key areas such as postquantum security and radio unit design. Additionally, it addresses emerging 5G advanced topics, including Industrial & URLLC, nonterrestrial networking, the role of artificial intelligence, 5G reduced capabilities for IoT, and self-organizing networks.