You ask:

"How is it possible to estimate the amount an infringer should pay if we don't know the exact amount the infringer infringed?"

I'll offer you something more to think about. First, if the above question were precisely answerable, it would only open the door to the question "what is each solitary infringement, by unit, worth?".

Personally, I seriously doubt that get into such arguments during license negotiations expecting to get anywhere. The licensor (TPL) would never achieve 20/20 visibility of the degree of infringement, and probably wouldn't want to set a specific amount to each solitary infringement as a way of determining a license fee.

You have to think about how negotiations actually happen. TPL demands a number, the prospective licensee balks, and they ultimately achieve compromise.

How to come up with that initial number (and pre-determined fall-back positions)? Based on the preceived criticality of the tech to the prospective licensor's business.

Here, DirecTV is a good example. Some 15M units in use incorporating our tech. Not a lot in the scheme of things (when compared to the number of products sold by say a Sony). But how critical is the tech to DirecTV's business? It all falls apart without it.

JMHO,

SGE