  The Cosmic Far-Infrared Background (CFIRB) contains information about the
number and distribution of contributing sources and thus gives us an important
key to understand the evolution of galaxies. Using a confusion study to set a
fundamental limit to the observations, we investigate the potential to explore
the CFIRB with AKARI/FIS deep observations. The Far-Infrared Surveyor (FIS) is
one of the focal-plane instruments on the AKARI (formerly known as ASTRO-F)
satellite, which was launched in early 2006. Based upon source distribution
models assuming three different cosmological evolutionary scenarios (no
evolution, weak evolution, and strong evolution), an extensive model for
diffuse emission from infrared cirrus, and instrumental noise estimates, we
present a comprehensive analysis for the determination of the confusion levels
for deep far-infrared observations. We use our derived sensitivities to suggest
the best observational strategy for the AKARI/FIS mission to detect the CFIRB
fluctuations. If the source distribution follows the evolutionary models,
observations will be mostly limited by source confusion. We find that we will
be able to detect the CFIRB fluctuations and that these will in turn provide
information to discriminate between the evolutionary scenarios of galaxies in
most low-to-medium cirrus regions.
