GSM Question:

The main difference between GSM and CDMA is: In GSM, the
entire frequency band is not available to the end-user,
while in CDMA the entire frequency band is available to the
end-user. So, the Frequency Re-use factor is 1 in CDMA.

GSM Works as follows:
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The entire frequency band is divided into chunks and
each such chunk is divided into timeslots and each such
portion is made available to a user.

CDMA Works as follows:
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The entire frequency band is available to the user. So,
in order to differentiate, the transmission from each user
is "spread" or coded using an unique code given to
individual user. At the receiving end, the spread
information is decoded.