A Zak transform is a effective method to investigate the theory of Gabor frames. Due to \(\mathbb R_{+}=[0,\,\infty )\) being not a group with usual addition, \(L^{2}(\mathbb R_{+})\) admits no usual Gabor frames and a usual Zak transform is not suitable for the study of \(L^{2}(\mathbb R_{+})\) -Gabor frames. However, \(\mathbb R_{+}\) is a group with “ \(\oplus \) ” addition. This paper addresses a class of multi-window Gabor systems associated with “ \(\oplus \) ” addition. Using a Zak transform associated with “ \(\oplus \) ” addition, we characterize “ \(\oplus \) ”-based Gabor frames (Riesz bases, orthonormal bases) and their (weak) Gabor dual frames. Also some examples are provided.