About the boundedness of the Fourier–Haar multiplicators

The boundedness of the Fourier–Haar multiplicators defined by the sequence $\lambda_{k,i}=\varepsilon_k=\pm 1,\;i=m$ and $\lambda_{k,i}=1$, if $i\neq m$, $m\in \mathbb N$, $m\geqslant 2$ is considered.
The equivalent conditions to the unconditional basis of the Haar system are received.