Development of a measurement system for spectrum awareness - DC estimation based on Welch-FFT

摘要

To resolve the spectrum scarcity problem, dynamic spectrum access (DSA) has been investigated recently. In DSA, an unlicensed user (secondary user: SU) can opportunistically access the unused spectrum (White Space: WS) owned by the licensed user (primary user: PU) while mitigating harmful interference from SU to PU. Key technique in DSA is spectrum sensing which is used to detect WS. However, implementing spectrum sensing in practice with reasonably low cost is very challenging due to the required detection accuracy and quickness. One possible approach to achieve the requirements is to use statistics regarding PU spectrum utilization in spectrum sensing. For this issue, it is necessary to develop a system for obtaining the statistical information, such as Duty Cycle (DC). In our previous work, DC estimation based on Welch-FFT has been investigated. In the DC estimation method, there is a trade-off relationship between DC estimation accuracy and WS detection accuracy with regard to the segment size of Welch-FFT. In this paper, we define the evaluation criteria for DC estimation accuracy and WS detection accuracy and provide the segment size design guideline in terms of DSA.