The Samsung Galaxy Note 4 is already a speedy phone, but there's a new version that can download over LTE even faster than before. The current version of the Galaxy Note 4 includes LTE-A with dual-band carrier aggregation — the ability to combine two frequency bands (carrier, in this case, is frequency on which the tower is broadcasting) — for downloads up to 150Mbps. The new version, however, bundles together three bands for downloads that can reach up to 300Mbps.
Of course, actually getting downloads that fast requires that your phone be connected to a tower supporting tri-band carrier aggregation as well as having ideal conditions (i.e. you're standing right in front of the tower) and the line delivering bandwidth to the tower also being capable of such speeds. Carrier aggregation also reduces the number of available bands for users, so you'll want to be hooking up when there are fewer people around.
All of this falls under the umbrella of "Category 6" LTE service, and the tri-band Note 4 will also support LTE-A Category 9 with up to 450Mbps download speeds, but that's not expected until later in 2015 (and will see the same restrictions as noted above for Cat 6).
Apart from the enhanced radios, the Samsung Galaxy Note 4 LTE-A seems to be more or less the same Galaxy Note 4 we reviewed in October. There's no word on which processor the phone runs on, or when or where we can expect it to be released, and how much you'll have to pay for the privilege of owning a phone capable of such blisteringly-fast downloads.