  In the context of a simple gauge-Higgs unification scenario based on the
gauge group SU(3) times U(1)' in a 5-dimensional flat spacetime, we investigate
a possibility to realize the Higgs boson mass of 125 GeV with a
compactification scale at the TeV. With the introduction of colored bulk
fermions in a certain representation under the gauge group with a half-periodic
boundary condition, we analyze the one-loop RGE of the Higgs quartic coupling
with the gauge-Higgs condition and successfully obtain 125 GeV Higgs boson mass
by adjusting a bulk mass for the fermions with a fixed compactification scale.
The Kaluza-Klein modes of the colored fermions contribute to the
Higgs-to-digluon effective coupling through the one-loop corrections. Since the
contribution is destructive to the Standard Model one and reduces the Higgs
boson production cross section, the recent LHC result gives a lower bound on
the mass of the lightest Kaluza-Klein mode fermion. We find the mass of the
lightest Kaluza-Klein mode fermion in the range of 2-3 TeV for 10%-5%
reductions of the Higgs boson production cross section through the gluon fusion
channel. Such Kaluza-Klein mode fermions can be discovered at the LHC run II
with sqrt{s}=13-14 TeV, and LHC phenomenology for the Kaluza-Klein fermions is
briefly discussed.
