Wireless spectrum in the US is carefully regulated to avoid interference, which is why mobile carriers pay out the nose to license slices of the airwaves. Naturally, T-Mobile was quite perturbed recently when it detected heavy interference with its network in Brooklyn. The FCC has investigated, and it turns out the culprit was a Bitcoin mining operation.
T-Mobile uses several wireless bands for its nationwide LTE network, but this interference affected its prized 700MHz spectrum. This is known as LTE band 12, and it’s present on all current T-Mobile phones and most unlocked devices. T-Mobile calls band 12 “extended range” LTE because of how well it propagates through obstacles like buildings.
The carrier told the FCC that signals from a local residence were disrupting its band 12 signals in Brooklyn, so the agency investigated. It turns out that one Victor Rosario had an at-home Bitcoin mining operation using the Antminer S5 (above). The Antminer is a purpose-built Bitcoin mining rig with ASIC (application specific integrated circuit) hardware. That means all it does is process Bitcoin transactions, but it’s faster at it than traditional computing hardware.
The Antminer S5 is not a wireless device, so it should not have been transmitting on the 700MHz band at all. There may have been a design flaw, or the owner of the devices might have made modifications that resulted in the spurious emissions. Either way, the FCC confirmed that when the miner was shut off, the interference stopped. It’s not uncommon for miners to modify their hardware to speed things up. The FCC doesn’t say if this device had been modified, but it seems unlikely every Antminer S5 could emit enough power to break T-Mobile’s network — this would have come up before now.
Okay, this @FCC letter has it all: #bitcoin mining, computing power needed for #blockchain computation and #wireless #broadband interference. It all seems so very 2018. https://t.co/EaXxmBAMXH
— Jessica Rosenworcel (@JRosenworcel) February 15, 2018
The Antminer S5 is no longer on sale (it was released in 2014), but the manufacturer has several newer versions. The S5 originally sold for $450, but some versions of the current Antminer S9 go for more than $2,000. A cheaper model will set you back under $300. These devices are intended to earn the owner Bitcoins in exchange for verifying transactions on the blockchain, but it’s hard to turn a profit on Bitcoin anymore. Most profitable mining operations are in countries with cheaper electricity.
The FCC hasn’t said all Antminers are illegal to operate, but the one in Brooklyn certainly is. Rosario has been barred from using the offending equipment. Continued usage could result in fines or seizure.