Littlewood--Paley--Rubio de Francia inequality in Morrey--Campanato spaces

Rubio de Francia proved the one-sided Littlewood--Paley inequality for arbitrary intervals in $L^p$, $2 \le p < \infty$. In this article, his methods are developed and employed to prove an analogue of such an inequality "beyond the index $p=\infty$", i.e., for spaces of H\"older functions and BMO.