GSM vs CDMA

GSM

Advantages of 2G GSM

* GSM has more stable network with robust features.
* Less signal deterioration inside buildings.
* Ability to use repeaters.
* Higher talktime in GSM phones due to the pulse nature of transmission.
* The availability of Subscriber Identity Modules (SIM) allows users to switch networks
and handsets.
* GSM covers virtually all parts of the world so international roaming is not a problem.
* Much bigger number of subscribers globally creates a better network effect for GSM
handset makers, carriers and end users.

Disadvantages of 2G GSM

* Pulse nature of TDMA transmission used in 2G interferes with some electronics, especially
certain audio amplifiers. 3G uses W-CDMA now.
* Intellectual property is concentrated among a few industry participants, creating barriers to
entry for new entrants and limiting competition among phone manufacturers.
* GSM has a fixed maximum cell site range of 35 km, which is imposed by technical limitations

CDMA

Advantages of CDMA

* Capacity is CDMA's biggest asset; it can accommodate more users per MHz of bandwidth
than any other technology.
* Has no built-in limit to the number of concurrent users.
* Uses precise clocks that do not limit the distance a tower can cover.
* Consumes less power and covers large areas so cell size in CDMA is larger.
* Able to produce a reasonable call with lower signal (cell phone reception) levels.
* Uses soft handoff, reducing the likelihood of dropped calls.
* CDMA's variable rate voice coders reduce the rate being transmitted when speaker is not
talking, which allows the channel to be packed more efficiently.
* Has a well-defined path to higher data rates.

Disadvantages of CDMA

* Most technologies are patented and must be licensed.
* Breathing of base stations, where coverage area shrinks under load. As the number of
subscribers using a particular site goes up, the range of that site goes down.
* Because CDMA towers interfere with each other, they are normally installed on much
shorter towers. Because of this, IS-95 may not perform well in hilly terrain.
* CDMA covers a smaller portion of the world, and CDMA phones are generally unable to
roam internationally.
* Manufacturers are often hesitant to release CDMA devices due to the smaller market, so
features are sometimes late in coming to CDMA devices.
* Even barring subsidy locks, CDMA phones are linked by ESN to a specific network, thus
phones are typically not portable across providers.