Upgrade to BW 7.3

Hello there,

We are contemplating upgrade to BW 7.3 from BW 7.01 EHP 1 SPS 7. Is this possible to upgrade from this version, and more importantly do we have to upgrade R/3 to 7.3 or we can just go with upgrading BW to 7.3 without upgrading R/3 components?

Thank you