CREAM: Unauthorized Secondary User Detection in Fading Environments

Dynamic Spectrum Access (DSA) has emerged as a major technology in the future wireless system to alleviate the worldwide spectrum scarcity issue. Authorized secondary users can take advantages of underutilized spectrum for communication. However, due to the open nature of the wireless medium, the DSA system suffers spectrum misuse by unauthorized secondary users, and thus fewer users would participate in DSA. Although many existing works have implemented misuse detection schemes into DSA, practical concerns, such as channel fading issues, are not well addressed. Therefore, how to ensure the reliable communication among authorized secondary users in a practical channel model becomes a challenging issue. In this paper, we propose CREAM, a physical-layer based misuse detection scheme specifically in the fading environment, which conceals the unforgeable spectrum permit into the message by superposition modulation for verification. Given the pre-shared secret information, the third-party verifier can perform efficient detection on unauthorized spectrum access. Detailed analysis and simulation results demonstrate the security, accuracy, efficiency, and low intrusion to message transmission in fading environments.