Precision Array for Probing the Epoch of Reionization (PAPER)[^4] [@parsons13], the Murchison Widefield Array (MWA)[^5] [@bowman13; @tingay13], the Giant Metrewave Radio Telescope (GMRT)[^6][@ghosh12; @paciga13] etc have dedicated a large amount of their observing resources to detect the signal from the epoch of reionization (EoR). While most of these telescopes are still not able to probe the very early stages of the EoR as they lack the very low-frequency detectors, the future radio telescope like the Square Kilometre Array (SKA)[^7] is expected to detect the signal even from the cosmic dawn. While the first generation telescopes are expected to detect the signal from the EoR statistically (e.g., in terms of the rms, power spectrum, skewness etc), the highly sensitive SKA1-low should be able to image the signal from cosmic [H [i ]{}]{} [@2015aska.confE..10M; @2015aska.confE..15W].

Recently, many studies have been done using analytical calculations [e.g., @furlanetto04; @2014MNRAS.442.1470P], semi-numerical simulations [@zahn2007; @mesinger07; @santos08; @Thom09; @choudhury09; @ghara15a; @ghara15b], and full numerical simulations involving radiative transfer [@Iliev2006; @mellema06; @McQuinn2007; @shin2008; @baek09] to understand the behaviour of the redshifted 21-cm signal from the cosmic dawn and EoR for different source models. Though most of these studies have concentrated in detecting the signal using statistical quantities, it 