Representations of unramified U(2,2) over a p-adic field I:   representations of non-integral level
  Let F_0 be a non-archimedean local field of odd residual characteristic and let G be the unramified unitary group U(2,2) defined over F_0. In this paper, we give a classification of the irreducible smooth representations of G of non-integral level using the Hecke algebraic method developed by Allen Moy for GSp(4). 
Michitaka Miyauchi