ECC6 EHP7 compatibility with BW 3.5

Hi,

We plan to upgrade from ECC6 EHP4 to EHP7. We would like to know EHP7 compatibility with the following SAP systems currently existing in the landscape:

SAP BW 3.5   (release 640)

SAP SCM4.10     (release 640)

SAP PI7.1   (release 710)

Do we have to consider upgrading above three systems also, is it mandatory.

I would really appreciate your suggestions and also if you can help with relevant document and notes.

Thanks

Ayush