Because of the diversity of information types and the complexity of information characteristics

traditionally

the multisource heterogeneous information is described and modeled by the corresponding knew theories

so there is rarely an unified method to fusion them. For several years

researchers have explored the unification of theories enabling the fusion of heterogeneous information and have finally considered random set theory. This paper first classifies available information by qualities (uncertain

vague

imprecise

etc) and then presents common theories that can be used to cope with them. Random set theory is introduced as a possible framework for unification. The reasons why the individual theories can fit in this framework are detailed. Finally

this paper reviews applications of random set theory in information fusion and discusses the possible directions in the future.