In a video released at the beginning of the Consumer Electronics Show in Las Vegas, Clearwire clearly demonstrates that it is very close to achieving the 100M-bps download speeds required by the ITU definition of 4G wireless communications. The company released a YouTube video of the tests, which are being conducted in Phoenix on an ongoing basis.
The Clearwire tests, which were conducted in a mobile environment, showed that by using the 20MHz bandwidth, Clearwire's LTE and WiMax are currently capable of producing 90M- to 95M-bps download speeds, with uploads in the 30M-bps range. This is dramatically faster than anything demonstrated by any other carrier, and it shows that with a few tweaks, Clearwire will reach the ITU's 100M-bps requirement to actually be considered 4G.
There are a few caveats, however. As you can see in the Clearwire tests, the actual throughput is impacted by the network infrastructure. Clearwire's tests exceeded the network capacity in one set of tests, and only when it used its own servers was it able to reach full speed. It's also worth noting that the Clearwire test environment was essentially one mobile tester having the network to itself, something that would never happen in real life.
But as Clearwire points out, the company has massive spectrum resources. Providing lightly loaded 20MHz channels to a large number of users is easier for Clearwire than it might be for other companies. The fact that it can provide these speeds with both WiMax and LTE also means that Clearwire may have room to accommodate more than one carrier. So if T-Mobile contracts with the company for LTE as it moves beyond its current HSPA+, Clearwire may be able to handle both Sprint and T-Mobile.
But this isn't to suggest that T-Mobile is resting on its laurels. That company also produced a video of its own speed tests conducted in Las Vegas using the existing T-Mobile HSPA+ network. T-Mobile has just announced that it has doubled the speed of its network from a theoretical 21M bps to 42M bps. The speed tests conducted by T-Mobile did not show anything close to the speeds that Clearwire was able to show, but the T-Mobile tests were conducted on a live network using existing laptop wireless cards.
Clearly there are speed differences between T-Mobile's HSPA+ and Clearwire's LTE and WiMax. T-Mobile was only able to get speeds of just under 30M bps despite the theoretical 43M-bps capability. But T-Mobile was using its operational network that presumably was also being used by all of those other T-Mobile customers out there in Las Vegas at this huge trade show. Clearwire had the network to itself.