Data rates for each user in ADSL with discrete multitone technique
ADSL is a point-to-point link. There's no &quot;multiple users&quot;; different telephone lines are different links, and the influence of one on the other is modeled as noise/inavoidable crosstalk.
So, every user gets all channels - or as many as the subscriber equipment (&quot;DSL modem&quot;) and the DSL access device negotiate (some channels are not usable due to e.g. interference from radio devices, and other aren't usable due to spectrum regulation laws, and maybe the ISP just limits the number of channels based on the contract the subscriber has – but that'd be unusual).
Only in the latest standards (G.fast and on), there's a notion of multiuser access and MIMO; it's called &quot;vectoring&quot; in the context of DSL. Your text doesn't concern itself with that at all. (And even if it were, that's cooperative multiuser-MIMO, not OFDMA as you're hinting at.)