Sunday, January 2, 2011

Adv. & DisAdv. of GSM and IS-95

Advantages of 2G GSM

  • GSM is mature; this maturity means a more stable network with robust features.
  • Less signal deterioration inside buildings.
  • Ability to use repeaters.
  • Talktime is generally higher in GSM phones due to the pulse nature of transmission.
  • The availability of Subscriber Identity Modules allows users to switch networks and handsets at will, aside from a subsidy lock.
  • GSM covers virtually all parts of the world so international roaming is not a problem.
  • The 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.[citation needed]
  • GSM has a fixed maximum cell site range of 35 km, which is imposed by technical limitations.[2]
Advantages of IS-95

  • Capacity is IS-95'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.[3]
  • Consumes less power and covers large areas so cell size in IS-95 is larger.
  • Able to produce a reasonable call with lower signal (cell phone reception) levels.
  • Uses soft handoff, reducing the likelihood of dropped calls.
  • IS-95'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 IS-95

  • Most technologies are patented and must be licensed from Qualcomm.
  • 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 IS-95 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.
  • IS-95 covers a smaller portion of the world, and IS-95 phones are generally unable to roam internationally.
  • Manufacturers are often hesitant to release IS-95 devices due to the smaller market, so features are sometimes late in coming to IS-95 devices.
  • Even barring subsidy locks, CDMA phones are linked by ESN to a specific network, thus phones are typically not portable across providers.

0 comments :

Post a Comment

 
Design by Free WordPress Themes | Bloggerized by Lasantha - Premium Blogger Themes | Blogger Templates