I am starting the upgrade of  CA Datacom/AD, CA Ideal for DB2, CA DBC and CA IPC. I see that CA Datacom/AD is at Version 15.0 but that the other products are at version 15.1.

Is there a CA Datacom/AD Version 15.1?

z/OS

CA Datacom/AD 15.0 is the current version; release date for “AD” 15.1 date has not been announced yet (as of this writing in July 2018).

CA Ideal for DB2 Version 15.1 (or 15.0) requires CA Datacom/AD 15.0. 
The Datacom environment should be upgraded to CA Datacom/AD 15.0 first so that the new DOCUMENT table is then present.
Then upgrade to the 15.1 versions of CA Ideal for DB2, CA IPC, and CA DBC to be at the latest.
 

Refer to KB000011500 “Finding CA Datacom Product Life Cycle Information for”
CA Datacom/CA Ideal/CA IPC Release and Support Lifecycle Dates
https://support.ca.com/us/product-content/status/support-life-cycle/indexes/ca-datacom-ca-ideal-ca-ipc-release-and-support-lifecycle-dates.html
Refer to the "CA Datac om/CA Ideal/CA IPC Maintenance Grid for z/OS"
https://support.ca.com/us/product-content/status/detailed-service-pack-info/ca-datacom-ca-ideal-ca-ipc-maintenance-grid-for-zos.html