You're right that multipath is very different from SAM and OAM from a theoretical point of view. Not so much from a practical point of view though.
In current point-to-point systems you often use SAM to give you two "channels" across the link, most often referred to as horizontal and vertical polarity, but you then hook that up to the same MIMO technology that you would use for multipath.
I would expect OAM to be exploited in a similar maner for point-to-point.
The fact that SAM is very difficult to exploit for capacity in cellular applications makes me think it will be even more difficult to exploit OAM. IF you ever see it implemented my money would be on using MIMO to exploit multipath + SAM + OAM, where multipath would dominate in complex radio environments and SAM + OAM in simple more point-to-point like environments.
In current point-to-point systems you often use SAM to give you two "channels" across the link, most often referred to as horizontal and vertical polarity, but you then hook that up to the same MIMO technology that you would use for multipath.
I would expect OAM to be exploited in a similar maner for point-to-point.
The fact that SAM is very difficult to exploit for capacity in cellular applications makes me think it will be even more difficult to exploit OAM. IF you ever see it implemented my money would be on using MIMO to exploit multipath + SAM + OAM, where multipath would dominate in complex radio environments and SAM + OAM in simple more point-to-point like environments.
But that's just an educated guess of course.