Currently the Tevatron is the only place where
$B_s$ mesons are produced. The mass difference of the $B_s$
and its antiparticle is not yet known. We present here
the development of a b-quark flavor tagger that largely
enhances the sensitivity power of the CDF experiment to
observe $B_s$ oscillations.
                                                                                     
This b-quark flavor tagging algorithm is based on
the charge correlation between the signal B meson and the
fragmentation tracks produced nearby. Relying on simulation
events, we evaluate the performance of the same side (flavor)
tagger on fully reconstructed Bu, Bd and Bs decay modes.