abstract: Structure and internal dynamics of cyclic polymer chains (ring polymers) in solution are influenced by excluded volume effects, which emerge either by mutual avoidance of spatially closed chains (geometrical entanglement), or as the result of the conservation of chain intrinsic topology. The present computational study discusses both effects in rings solutions of very different monomer concentration: in particular, we report on the crossover from dilute to semi-dilute conditions, i.e. above the transition concentration where nearby chains start overlapping.