Spectrum Database Aided Prior Vacant Frequency Band Detection for Spectrum Sharing

Spectrum sharing allows multiple users, i.e., a primary user (PU) and secondary users (SUs), to share the same frequency band while protecting the communication quality of the PU. Therefore, when an SU shares the same frequency band as the PU, it is necessary to protect the PU's communication temporally and spatially. In general, the protected area is constructed to guarantee the PU's transmission, by disabling frequency sharing within this area. However, this area is generally set to be wider than necessary, and the area that can be shared is limited. In addition, if the SU detects communication from the PU during frequency sharing, the SU must immediately switch to another frequency band to protect the PU communication. With existing technology, the presence or absence of PU communication is judged instantaneously, so the SU temporarily stops transmission at the moment of switching to another frequency band. A spectrum database (SD) stores measured values such as received signal strength (RSS) of the PU has been considered to be a solution for spectrum sharing. In this research, we develop an algorithm that uses the information stored in the SD to detect the vacant frequency in advance by taking into account the moving direction of SU.