  In this article, we utilize the scale-invariant Strichartz estimate on
waveguide which is developed recently by Barron \cite{Barron} based on
Bourgain-Demeter $l^2$ decoupling method \cite{BD} to give a unified and
simpler treatment of well-posedness results for energy critical nonlinear
Schr\"odinger equation on waveguide when the whole dimension is three and four.
