In this paper we study the property of asymptotic direction for random walks
in random i.i.d. environments (RWRE). We prove that if the set of directions
where the walk is transient is non empty and open, the walk admits an
asymptotic direction. The main tool to obtain this result is the construction
of a renewal structure with cones. We also prove that RWRE admits at most two
opposite asymptotic directions.Comment: revised versio