The document discusses security issues with 4G networks. It first provides an overview of 4G network architecture, including the IP Multimedia Subsystem security architecture and next generation network security architecture. It then discusses eight security dimensions for 4G networks: access control, authentication, non-repudiation, data confidentiality, communication security, data integrity, availability, and privacy. Finally, it outlines some specific security issues with 4G, including physical layer issues, WiMAX MAC layer issues, denial of service attacks, and Wi-Fi security issues.