Hi Reddy,
Using BODS (BusinessObjects Data Services) extract data from EXCEL File and transform them into meaningful information and load them into table in DB2 or MS Access system with ease (or any type of Data Sources as per you requirement). Then create a universe and build business layer or you can add this newly created table (having Excel Data) into the existing Universe. Hence you can achieve creating a semantic layer with less complexity on EXCEL and DB2 Data source.
Hope this information helps you...
--Raji. S