If you are searching online for information about multiple Authentication Providers in Oracle BI 11g, you could find references (even on my own blog) to Doc Id; 1428008.1 on My Oracle Support (MOS). Via this note you were able to obtain following: TechNote_LDAP_Auth_DB_Groups_V3.pdf.
If you try to find this note now, you won’t be able to find it. It seems that the note has been closed. You should be able to find the information you are looking for here (Configuring LDAP as the Authentication Provider and Storing Groups In a Database)