WiMAX

WiMAX is a wireless broadband access standard developed and maintained by the IEEE under the 802.16 designation.  As its name suggest,WiMAX can be thought of as an extension of Wi-Fi designed
to enable pervasive, high-speed mobile Internet access on a wide range of devices, from laptops to smartphones.The current implementation is based on the 802.16e specification which offers theoretical downlink rates upwards of 70Mbps and up to 30-mile ranges.

Again, "theoretical" is the keyword here as WiMAX, like all wireless technologies, can either operate at higher bitrates or over longer distances but not both. Production networks being operated in the United States are seeing average speeds go from 3 to 6Mb/s, with bursts up to 10Mb/s. Like LTE -- and Wi-Fi 802.11n for that matter -- WiMAX supports MIMO technology, which means that additional antennas can increase the potential throughput.

There is no uniform global licensed spectrum for WiMAX, but three have been listed: 2.3 GHz, 2.5 GHz and 3.5 GHz. In the U.S., the biggest segment available is around 2.5 GHz and is already assigned primarily to Clearwire, a wireless internet service provider in which Sprint Nextel holds a majority stake.

In terms of total available 4G spectrum to deploy their services, Clearwire has several times more than its competitors, which have smaller portions of the 700 MHz band. However, Verizon and AT&T are not too worried about this as they can re-utilize spectrum being used right now for 2G and 3G services by upgrading these to LTE when the demand is there.

Furthermore, as mentioned earlier, the 700 MHz band that both Verizon and AT&T plan to use has enormously better range and penetration of buildings than the same power of signal at 2.5 GHz. Some experts have said that 700MHz will require as few as one-quarter as many base stations to offer identical coverage to 2.5 GHz.
Source - IEEE