I used this several years ago (five or six, I think? Maybe more) with some of Ettus Research's USRPs. It's quite amazing. We used it for prototyping -- the gear

I used this several years ago (five or six, I think? Maybe more) with some of Ettus Research's USRPs. It's quite amazing. We used it for prototyping -- the gear wasn't (or we couldn't get it to be) fast enough to replace "real" LTE gear, but do bear in mind this was many years ago. But at the time, this was basically the best way to experiment with, and develop solutions for LTE, in a price range that was mostly affordable for a small company. I know cheaper options exist today, but I don't know much about them. And, of course, this warrants a shout out for Ettus Research's equipment. It's pricey but if you can afford it, or if you manage to strike a bargain, you'll love it. The higher-ups at the company I was working for at the time were kind enough to let me spend several evenings there using the equipment for my own hobby projects. I mostly used it with GNU Radio -- it worked without a glitch.