  We present calculations of two-pion and two-kaon correlation functions in
relativistic heavy ion collisions from a relativistic transport model that
includes explicitly a first-order phase transition from a thermalized
quark-gluon plasma to a hadron gas. We compare the obtained correlation radii
with recent data from RHIC. The predicted R_side radii agree with data while
the R_out and R_long radii are overestimated. We also address the impact of
in-medium modifications, for example, a broadening of the rho-meson, on the
correlation radii. In particular, the longitudinal correlation radius R_long is
reduced, improving the comparison to data.
