  Context. MHD waves are proposed to transport sufficient energy from the
photosphere to heat the transition-region (TR) and corona. However, various
aspects of these waves such as their nature, propagation characteristics and
role in the atmospheric heating process remain poorly understood and are a
matter of further investigation. Aims. We aim to investigate wave propagation
within an active-region (AR) plage using IRIS and AIA observations. The main
motivation is to understand the relationship between photospheric and TR
oscillations. We plan to identify the locations in the plage region where
magnetic flux tubes are essentially vertical, and further our understanding of
the propagation and nature of these waves. Methods. We have used photospheric
observations from AIA (i.e., AIA 1700 {\AA}) as well as TR imaging observations
(IRIS/SJI Si iv 1400.0 {\AA}). We have investigated propagation of the waves
into the TR from the photosphere using wavelet analysis (e.g., cross power,
coherence and phase difference) with inclusion of a customized noise model.
Results. Fast Fourier Transform(FFT) shows the distribution of wave power at
photospheric & TR heights. Waves with periods between 2.0- and 9.0-minutes
appear to be correlated between the photosphere and TR. We exploited a
customized noise model to estimate 95% confidence levels for IRIS observations.
On the basis of the sound speed in the TR and estimated propagation speed,
these waves are best interpreted as the slow magneto acoustic waves (SMAW). It
is found that almost all locations show correlation/propagation of waves over
broad range of period from photosphere to TR. It suggests the wave's
correlation/propagation spatial occurrence frequency is very high within the
plage area.
