This paper proposes the utilization of GSM logical channels (RACH, AGCH and TCH) and UMTS signaling (MIB and SIBs) of the Broadcast Channel to transmit a Cognitive Beacon Channel (CBC). The CBC will help to improve spectrum awareness by conveying signalization to mobile users in a multiRadio Access Technology (RAT) environment (e.g. 3GPP, Wi-Fi, WiMAX and future cognitive radio systems). Taking advantage of this spectrum knowledge, the purpose of the CBC is to transmit the necessary information to allow Dynamic Spectrum Access (DSA) using a centralized architecture. The principal motivation of this proposition is to obtain benefit from existing 3GPP technologies proved to be efficient and accepted. Simulation results show that our proposals, using logical channels of GSM and UMTS outperform, respectively, the Ondemand and the Broadcast CPC implementations of the E2R II project. Keywords- Cognitive Beacon Channel (CBC); GSM; UMTS; Cognitive Radio Systems; Multi- Radio Access Technology;...