  The India-based Neutrino Observatory (INO) will host a 50 kt magnetized iron
calorimeter (ICAL) detector that will be able to detect muon tracks and hadron
showers produced by Charged-Current muon neutrino interactions in the detector.
The ICAL experiment will be able to determine the precision of atmospheric
neutrino mixing parameters and neutrino mass hierarchy using atmospheric muon
neutrinos through earth matter effect. In this paper, we report on the
sensitivity for the atmospheric neutrino mixing parameters
($\sin^{2}\theta_{23}$ and $|\Delta m^{2}_{32}|$) for the ICAL detector using
the reconstructed neutrino energy and muon direction as observables. We apply
realistic resolutions and efficiencies obtained by the ICAL collaboration with
a GEANT4-based simulation to reconstruct neutrino energy and muon direction.
Our study shows that using neutrino energy and muon direction as observables
for a $\chi^{2}$ analysis, ICAL detector can measure $\sin^{2}\theta_{23}$ and
$|\Delta m^{2}_{32}|$ with 13% and 4% uncertainties at 1$\sigma$ confidence
level for 10 years of exposure.
