Aren't they considered "essential patents" that must be made available at a reasonable price?

Generally yes. But you would need to spend 3 years in court to get that to work.

Follow-on question for the sake of debate: what if you got a bunch of smaller wannabe startups and interests backing a group effort to do exactly this for a pool of things? Would the legal fees scale linearly? :/

Care to expand? Is that why Software Define Radio is still so much a niche and expensive?

Nearly all modern radio chipsets are mostly software defined. That includes WiFi, LTE and GPS.

The radio frontend is typically a downmixer and then straight into digital.

Some of the typically "software" bits like FFT's, various encodings, checksums, clock recovery etc. are frequently done in digital hardware acceleration blocks for performance, and saving power. If you were writing the firmware of the device, you needn't use them though.

With enough human years of effort, you could take almost any radio hardware for sale today and repurpose it to speak nearly any other radio protocol in similar frequency bands. Performance will probably be terrible though!

It's rare people do this though - all the chips don't have their firmware documented (again mostly to avoid publishing documentation that proves they are violating someone elses patents), and many have various cryptographic elements that makes reverse engineering hard.

The one exception to this is WiFi chips used in the Nexus 5 by Broadcom, which has had a reasonable amount of reverse engineering because Broadcom accidentally published the source code because the firmware code was in part shared with published Linux kernel driver source code.

> all the chips don't have their firmware documented (again mostly to avoid publishing documentation that proves they are violating someone elses patents)

:O

Enlightenment moment :(

There are a gazillion patents on radio related stuff. Nearly all standards have associated patents.

Companies already in the industry typically have cross-licensing agreements - ie. I can use your patents if you can use mine. Either that or they just violate each others patents knowing that a patent war would be mutual destruction and in neither companies interests.

But a newcomer has nothing to offer - the minute they release any product, every incumbent company will go through their patent portfolio and sue them out of the water.

Yikes, that sounds pretty harsh. So how would a new player be able do enter?

I thought only the hardware could be patented, not the software, and so SDR would level the playing field, but that's perhaps too naive?