2020 Volume 9 Issue 1 Pages 13-18
In order to achieve high-speed and large-capacity communication, efficient use of frequency resources even over different wireless communication systems is an important issue. We previously proposed the spectrum superposing scheme using subcarrier transmission power assignment (STPA) and blind adaptive array (BAA). Even when multiple systems use the same frequency band, the secondary system enables the both receivers to mitigate inter-system interference by STPA-BAA. However, STPA-BAA has a problem that the operational region of the secondary system is limited due to low-level subcarriers. This paper attempts to resolve this issue by introducing subcarrier modulation adaptation. It can effectively expand the operational region of our proposed approach even in the low signal-to-noise-power-ratio (SNR) situation.