Why CDMA is able to use whole band, when Wimax is subchanneled?
Why CDMA is able to use whole band, when Wimax is subchanneled?

Because code division is based on decorrelation (orthogonality) of signals as opposed to traditional separation across frequency spectrum and/or time. So CDMA allows to operate concurrently, the same time, in the same frequency band, in the same geographical spot.

To understand how it works, look at M-Sequencies.

From high level look at spectrum, code division, walsh patterns etc. as different types of orthogonality. They all are equally limited in terms of informational capacity with presence of noises. But frequency spectrum is simplier technically, because it is a scalar, not some "code space" thing.