If you want to perform IDoc inbound processing in the background, you require a background user in every child system that you can use instead of your own user name to schedule the background jobs in transaction SM37.
1. In the child system, choose Tools ® Administration ® User Maintenance ® User (transaction SU01).
2. Create a background user in accordance with the naming convention for system users (such as CUA_PRD_BACK).
3. Assign the user type System to the user, and deactivate the password (see Logon Data Tab Page).
4. Assign the role Z_SAP_BC_USR_CUA_CLIENT_BATCH to the user.
5. Save your entries.