GSM stands for Global System for Mobile Communication and it operates on three frequencies 900,1800 and 1900 MHz.But in India we're using 900 and 1800 MHz.It uses time division multiple access(tdma) and frequency division multiple access(fdma).
CDMA stands for Code division multiple access.It operates on 450,800 and 1900 MHz.But we're using 800MHz.
But the main difference between GSM and CDMA is,in GSM the transmission media is air and in CDMA the transmission media is optical fibre cable and it works on the principle of total internal reflection.
gsm abbriviat the globle System for Mobile Communications..............
GSM is the “branded” term referring to a particular use of
TDMA (Time-Division Multiple Access) technology. GSM is the
dominant technology used around the globe and is available
in more than 100 countries. It is the standard for
communication for most of Asia and Europe. GSM operates on
four separate frequencies: You’ll find the 900MHz and
1,800MHz bands in Europe and Asia and the 850MHz and
1,900MHz (sometimes referred to as 1.9GHz) bands in North
America and Latin America. GSM allows for eight
simultaneous calls on the same radio frequency and
uses “narrowband” TDMA, the technology that enables digital
transmissions between a mobile phone and a base station.
With TDMA the frequency band is divided into multiple
channels which are then stacked together into a single
stream, hence the term narrowband. This technology allows
several callers to share the same channel at the same time.
2. CDMA abbriviat theC ode Division Multiple
Access.............................. CDMA takes an
entirely different approach from GSM/TDMA. CDMA spreads
data out over the channel after the channel is digitized.
Multiple calls can then be overlaid on top of one another
across the entire channel, with each assigned its
own “sequence code” to keep the signal distinct. CDMA
offers more efficient use of an analog transmission because
it allows greater frequency reuse, as well as increasing
battery life, improving the rate of dropped calls, and
offering far greater security than GSM/TDMA. For this
reason CDMA has strong support from experts who favor
widespread development of CDMA networks across the globe.
Currently, you will find CDMA mostly in the United States,
Canada, and North and South Korea. (As an interesting
aside, CDMA was actually invented for the military during
World War II for field communications.)
gsm used unique number throught word and coverage is very good.
cdma uses seperate code for each user so frequency is very
high for each user. entire bandwidth is dedicated to each
user.where as in gsm entire BW in divided into time slots
and frequency slot
a. Data Transfer Speed : With the advent of cellular phones
doing double and triple duty as streaming video devices,
podcast receivers and email devices, speed is important to
those who use the phone for more than making calls. CDMA
has been traditionally faster than GSM, though both
technologies continue to rapidly leapfrog along this path.
Both boast "3G" standards, or 3rd generation technologies.
EVDO, also known as CDMA2000, is CDMA's answer to the need
for speed with a downstream rate of about 2 megabits per
second, though some reports suggest real world speeds are
closer to 300-700 kilobits per second (kbps). This is
comparable to basic DSL. EVDO is in the process of being
deployed. It is not available everywhere and requires a
phone that is CDMA2000 ready.
GSM's answer is EDGE (Enhanced Data Rates for GSM
Evolution), which boasts data rates of up to 384 kbps with
real world speeds reported closer to 70-140 kbps. With
added technologies still in the works that include UMTS
(Universal Mobile Telephone Standard) and HSDPA (High Speed
Downlink Packet Access), speeds reportedly increase to
about 275—380 kbps. This technology is also known as W-
CDMA, but is incompatible with CDMA networks. An EDGE-ready
phone is required.
b. Subscriber Identity Module (SIM) cards : In most of the
countries only GSM phones use SIM cards. The removable SIM
card allows phones to be instantly activated, interchanged,
swapped out and upgraded, all without carrier intervention.
The SIM itself is tied to the network, rather than the
actual phone. Phones that are card-enabled can be used with
any GSM carrier.
The CDMA equivalent, a R-UIM card, is only available in
parts of Asia . CDMA carriers require proprietary handsets
that are linked to one carrier only and are not card-
enabled. To upgrade a CDMA phone, the carrier must
deactivate the old phone then activate the new one. The old
phone becomes useless
c. Roaming : For the most part, both networks have fairly
concentrated coverage in major cities and along major
highways. GSM carriers, however, have roaming contracts
with other GSM carriers, allowing wider coverage of more
rural areas, generally speaking, often without roaming
charges to the customer. CDMA networks may not cover rural
areas as well as GSM carriers, and though they may contract
with GSM cells for roaming in more rural areas, the charge
to the customer will generally be significantly higher.
d. International Roaming : If you need to make calls to
other countries, a GSM carrier can offer international
roaming, as GSM networks dominate the world market. If you
travel to other countries you can even use your GSM cell
GSM 900 & GSM 1800 are used in india, But, GSM 1900 used in
GSM and CDMA techniques can be explained with an example,
suppose there are 10 persons in a room and they want to
communicate with each other .How can they communicate?
First method:One persons speaks at one time that means we
have provided a definite time interval to that person.-GSM
Second method :all the peers speak at a time in a different
language which we call as CDMA
CDMA stands for Code Division Multiple Access and GSM
stands for Global system for Mobile Communication.
In CDMA phones the software is integral with the phone
instrument and in the case of GSM phones it is through the
CDMA phone instruments are dedicated to the service
provider. GSM phone instruments are portable across service
providers through SIM cards.
1.What is the difference between Diplexer and Duplexer and
2. What is the different between CDU C and CDU A
3. How do you link a T1 from the 1st BTS to 2nd BTS
4. What is the value for TEI 1st T1?
5. What is the SSI?
Which is the digital modulation used today in telecomn?
(whatever his question meant the answer was CDMA)
2) Why is walse code used? then, noncoherent detection,
coherent detection, Pn code(y it is used?) etc