yes, time multiplexing is the key… a same time-slot position will be used by different TBF at different time (or rather, at different frame).
it’s much easier to explain it with a drawing !
datarate in GSM and GPRS…
main difference is that in GSM, you are limited to the use of one timeslot. Whereas in GPRS, you can use up to 4 timeslots in downlink.
Then, you can use different coding schemes in GPRS, to make the usage of a timeslot more efficient (less protection code, more useful data).
In GPRS, you can reach about 40 to 80 kbps.
In EDGE, up to 220 kbps.
EDGE is using a different air modulation, sending more information within one signal. (you’ll need to goole it, because the explanations are long and complex)