Abstract : In this proceeding, I show some features of Loop Quantum Cosmology (LQC) through cosmological perturbations and their consequences on the Cosmic Microwave background (CMB). It has been known for quite a long time that tensor perturbations are a promising way to possibly investigate the predictions of theories of gravitation. However, we have recently understood -in particular thanks to the study of vector and scalar modes-that the algebra usually assumed was in fact not correct. The requirement of anomaly-freedom for vector and scalar perturbations leads to modifications of the tensor-mode algebra, especially for the two main corrections implied by LQC, namely the holonomy and inverse-triad terms. For the holonomy corrections in the bouncing scenario, it exists a possible generic way to derive the anomaly-free and gauge-invariant variables which revealing a specific scheme (the so-called mu-bar scheme), usually assumed for other reasons. This model shows finally an “effective” change of the metric signature (from lorentzian to euclidean) around the bounce, possibly bridging this approach with the Hartle-Hawking proposal and with the effect of Asymptotic Silence.