said by Matt3:
WiMax can use TDD or FDD. Neither is "more compatible" with the 2.5GHz frequencies.
While theoretically true, FDD WiMAX has not been deployed anywhere in the world and is not commercially available. FDD requires paired channels while TDD does not. That probably isn't a problem in the US but some countries either don't allow or don't have paired channels available at 2.5 GHz.