Le lemme fondamental pour les groupes unitaires

Let G be an unramified reductive group over a non archimedian local field F. The so-called "Langlands Fundamental Lemma" is a family of conjectural identities between orbital integrals for G (F) and orbital integrals for endoscopic groups of G. In this paper we prove the Langlands fundamental lemma in the particular case where F is a finite extension of Fₚ ( (t) ), G is a unitary group and p>rank (G). Waldspurger has shown that this particular case implies the Langlands fundamental lemma for unitary groups of rank