That's the hard part ... what of the 4.5 billion relates to LTE ... We could find out later this week as more information is disclosed with or without any objections from the losing parties. IMO, most of it, likely, given how this auction was advertised. Backing out the RIM's tax loss share, networking patents, storage patents and others in my opinion would be immaterial so a guesstimate that 80% of 4.5 billion relates to LTE may be high, low and/or close to the actual.
If you want to have fun with numbers, a quick and dirty way is to go with the idea that $2.1 billion came from Ericsson, Sony, Microsoft and RIM for a paid-up LTE license from Apple. Treat that as cash flow in year-one. Determine what the percentage of those four represent in the future LTE market (less exact, assume the current market statistics will be the same as LTE), extrapolate the $2.1 billion over the unlicensed remainder (Samsung, LG, NEC etc.) as future cash flow in years 2-5 to be received from the remaining market which has not yet licensed. Net present value the cash flow to an approximate valuation. It will be more than $2 billion.