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Reply To: Cell Planning


Hi Daniel, may be this basic definition could help you (from some documentation):
A TDMA frame consist of eight timeslots or physical channels. Each timeslot
has a length of 0.577 ms. The length of a TDMA frame is therefore 4.615 ms.
A 26-TDMA multi-frame is defined as a succession of 26 TDMA frames, and
corresponds to exactly 120 ms (26 x 4.615ms) cycle used for the TCH/F and
A 51-TDMA multi-frame is defined as a succession of 51 TDMA frames, and
corresponds to a 235 ms (51 x 4.615ms) cycle.
A Super-frame is a succession of 51 x 26 TDMA frames (6.12 sec). This is
the smallest cycle for which the organization of all channels is repeated,
because of these smallest common denominators.
A Hyper-frame is a succession of 2048 x 51 x 26 TDMA frames (3 h, 28 min,
53 sec & 760 ms). It is a numbering period and determines all the cycles in the
transmission of the radio path. The frame number in the hyper-frame (absolute
TDMA frame number) is e.g. the smallest cycle used for frequency hopping
and ciphering.
We have seen that a physical channel is defined by a frequency and a timeslot
number. We have also seen that a physical channel can be used to carry various
logical channels. At any point in time, the MS must know on which logical channel to
send to the BTS and which logical channel is being sent from the BTS. For example
the timeslot allocated to a user is usually used for traffic (TCH) but sometimes is used
for signalling (either FACCH or SACCH). The MS and BTS must know when to
send/receive each of these logical channels.
In order to achieve this, sequences of logical channels are defined. They are called
‘multi-frames’. There are two types of multi-frames. The traffic channel multi-frame is
26-TDMA frames long, and the BTS signalling multi-frame is 51 TDMA frames long.
Each multi-frame can have different combinations of logical channels depending on
the configuration of the BTS.