When what is called 'tethering' today first became fashionable to a few geeks at the end of the 1990's, Bluetooth was the technology of choice and it was well suited for the data rates in 2G mobile networks of a few tens of kilobits per second. But over time, mobile networks outgrew Bluetooth's capabilities when the technology could not evolve beyond around 2 Mbit/s. Here's an interesting post I published back in 2007 if you care for the historical perspective. Fortunately, Android pushed Wi-Fi tethering to the masses in around 2010 and for some time it looked like it could keep pace with theoretical peak data rates in mobile networks. At some point I had my doubts it could in such small devices when LTE data rates reached 100 Mbit/s and beyond. But it looks Wi-Fi chipset manufacturers were not sleeping as Anandtech reports in this post that they have measured a maximum throughput of over 400 Mbit/s in the Samsung Galaxy S5. And it's by far not the only device anymore going well beyond the 200 Mbit/s line with 802.11ac. Such speeds are likely to be only reached at close range but that's how tethering is mostly used anyway.