GSM Physical and Logical Channels

Physical Channels:

A physical channel is specified by a specific time slot in a specific channel
carrier frequency

logical channels:

run over a physical channel, but not necessarily in all its time slots
are classified into traffic channels and control channels
have to be managed: set up, maintenance, tear down

Control channels:

Control channels are interspersed with traffic channels in well-specified
ways (e.g. every 26 TDMA frames a logical channel gets bandwidth in a
physical channel)