The field of VANET is still on growing stage and need a lot of improvements in terms of routing, the internet, etc. If you have any novel idea to apply any kind of internet architecture, which is able to enhance the internet services, so you will go with that as your PhD topic. Different studies have been proposed a different kind of internet architectures for VANET. 

Information-centric networking (ICN)  provides a infrastructure for internet, which is away from a host-centric paradigm and based on perpetual connectivity and the end-to-end principle. 

A content-centric network is a network of data or files organized by their content or name, rather than by geo-location or domain address.

Named Data Networking (NDN) is also related with Content-Centric Networking (CCN).