A novel synchronization technique is proposed for a heterogeneous cognitive radio combining a public safety mobile communication system (PMCS) with a commercial mobile wireless communicationsystem (CMWCS). Since the PMCS is crucial in public safety activities such as search-and-rescue operations, we have implemented a heterogeneous cognitive technique to improve the communicationquality of the PMCS. To combine the PMCS with the CMWCS properly, the proposed synchronization technique enables not only the co-synchronization between the PMCS and the CMWCS but also the self-synchronization of the PMCS.
In this paper, we especially focus on the PMCS’s self-synchronization that is one of the most difficult parts of our proposed cognitive radio system. The proposed technique is utilized for systems employing differentially encoded 7t/4-shift QPSK modulation. The synchronization can be achieved by correlating the envelopes calculated from the PMCS’s received signals with subsidiary information (SI) sent via the CMWCS. In this study, the performance of the proposed synchronization technique is evaluated by computer simulation.