What technologies or techniques are practical for minimizing cheating and collaboration in a University final examination that is to be held online?

I have seen some third-party arrangement which requires the student to keep a webcam operating during the entire duration of the examination, and read here of using a Zoom teleconference to monitor all the students as kind of a remote proctoring.

As we get into the fall term with COVID-19 restrictions still in place in many countries, this has to be a common concern to ensure the value of the resulting credentials. My immediate question is triggered by a colleague teaching an advanced undergraduate 4th year online course in an engineering discipline, and the student body is pretty international both ethnically and probably (at that time) geographically, so time zone differences may be a factor. Questions are more theoretical than numerical so the MOOC techniques of randomizing are unlikely to be of much value.

My thought is that some form of remote proctoring (preferably by an as-yet unidentified trusted third party recording the webcams and flagging suspected transgressions) and to force the students into one compromise time period (regardless of their location and time zone) would suffice.