False.

Manors do not, but CDMA does.

False.

True.

GSM can hand off within a network, but with a few very minor exceptions,
not between networks without dropping the call.

False, although echo suppressors may make it seem that way some times.
Channel timing assignements are offset, so that timing slot 1 is not
the same time on the up link as it is on the downlink. I.E.
Transmitter and receiver are not actually operating simultaneously. In
addition, if there is nothing to transmit, nothing is transmitted. The
background noise you hear is actually generated in the phone by a
'noise' descriptor provided by the network.

On an AMPS phone, Duplexing is a problem, because it is tough to have
the receiver listen for picowatts, while the transmitter is operating
at watts and you are sharing the antenna. D-AMPS/TDMA avoids it
because like GSM, the timing slots are offset, so you don't actually
have to transmit and recieve at the same time.

FALSE.

False, both use power loop control. (however GSM at 1800 and 1900Mhz
is limited to 1 watt in hand helds), mobile installations (cars) are
actually defined up to 20 watts, but I don't think I have ever seen
one with more than 5 watts.

However the power loop control is crucial to the operation of CDMA,
whereas the major benefit in GSM is battery life. The down side for
CDMA is network capacity is actually defined not by the number of
users, but by the total power in the channel. CDMA is the digital
analog of synchronous detection. The receiver decides whether this
particular piece of data is part of your call by intergrating the
output. If you remember your calculus, the intergral of the product of
two signals is zero over time unless the two signals are the same
frequency. So by applying the spreading code, you are in effect
engaged in synchronous detection. Any spreading code other than one
the signal was transmitted with, will integrate over time (even very
short times) to ZERO, so it is discarded. The problem is that sudden
changes in signal level can cause it to be non-zero for brief periods.
To be polite, this is NOT good.

As a result, CDMA adjusts output  power by +/- 1db  960 times per
second, come hell or high water, and because total power in the band
determines capacity, CDMA uses as little as it can get away with. In
part this works because of the Shannon Theorem. Which says that the
capacity of a channel is related to both it's bandwidth, and the
signal to noise ratio. If you make the channel wide enough (GSM is
200Khz, CDMA is 1.23Mhz IIRC, CDMA can operate with much lower signal
to noise ratios than GSM can because it uses a much wide channel.

The other good news is CDMA has no implicit range limitations. GSM
does. There are 8 x 217 time slots per second, and not much time in
between. 1 microsecond at the speed of light is 300 meter, or about
1000 feet. You get more than a mile or so away the Base, is nothing is
done, you will slide into the next time slot. So GSM incorporates
someting called timing advance. The BTS is able to determine the
distance from the phone to the BTS based upon the timing it sees on
the control channel, and advances the start of transmit cycle in the
time slot, The adjustment ranges from 0-63, which allows the signal to
reach the BTS within the assigned slot at distances up to 35km.

Beyond that something has to give. If you are even in light aircraft,
or high in a building, a GSM phone may be able to see a BTS that is
more than 35 km away, but you cannot use it because you can never get
messages to the BTS within your assigned time slot, so you can never
register. While in Bahrain for example, In the upper floors of a
hotel, you can pick up BTS's in Saudi Arabia, but you cannot place
calls with them because you are more than 35km away.

In some parts of Rural Australia, the adjacent time slot is
'sacrificed', reducing the channel capacity from 8 to 4, to allow
signals to be received in the adjacent time slot, allowing the 35km
limit to be exceeded, however I am unaware of this being used anywhere
else.

GSM doesn't drop calls unless a priority call forces you out, or you
are handed off to a BTS at full capacity. If you try to initiate a
call in a cell that is at capacity, the call simply cannot be
established. As a result, dropped calls on GSM networks are rare.

In a CDMA network, just changing how you use the phone, or a new call
being established can cause other calls to be randomly dropped. A CDMA
network sees all calls other than yours as noise. If the background
noise level gets too high, your signal can no longer be reliably
decoded, and the call  is dropped.  The  other killer can be something
called fast Rayleigh fading, which is a type of
constructive/destructive interference from multipath reflections. If
it happens faster than the power loop can deal with it, the call will
be dropped. A fair number of drivers with CDMA in the PCS band and a
heavy foot have had this happen, and all they know is the call was
dropped.  GSM deals with fast rayleigh fading by havig much higher
signal to noise ratios to start with.

True, however the lastest CDMA phones support SIM's as well. It makes
International Roaming a lot simpler.

Wrong, the handoff occurs in a single time slot, about 600
microseconds. YOu will never talk to two BTS's at the same time, but
the period of non-contact is very short, and is transparent to the
point that you  are unlikely to  be able to detect it. The Phone
doesn't have to find the next BTS, it is told where it is, and simply
asks the new BTS to assign it a new channel and time slot. Meanwhile,
data is held at both ends for the few milliseconds it takes to do
this. The most you are likely to notice is a click.

However if you happen to move into a cell with no available time
slots, the call will indeed be dropped because it cannot be handed
off. That is a very rare event, because it is bad for business.