  N-extended massless arbitrary integer and half-integer spin supermultiplets
in four dimensional flat space are studied in the framework of light-cone gauge
formalism. For such multiplets, by using light-cone momentum superspace, we
build unconstrained light-cone gauge superfield formulation. The superfield
formulation is used to develop a superspace representation for all cubic
interactions vertices of the N-extended massless supermultiplets. Our suitable
treatment of the light-cone gauge superfields allows us to obtain attractively
simple superspace representation for the cubic interaction vertices. Superspace
realization of relativistic symmetries of the N-extended Poincare superalgebra
on space of interacting fields is also obtained.
