Telecommunications Blog

 I want to speak about messages in CDMA , how it sent and what the call processing

**  In CDMA, most call processing events are driven by messages.
** Some CDMA channels exist for the sole purpose of carrying, they never carry user’s voice traffic.
          • Sync Channel (a forward channel).
          • Paging Channel (a forward channel).
          • Access Channel (a reverse channel).
          • On these channels, there are only messages, continuously all of the time.
** Some CDMA channels exist just to carry user traffic.
          • Forward Traffic Channel.
          • Reverse Traffic Channel.
          • On these channels, most of the time is filled with traffic and messages are sent only when there is something to do.
** All CDMA messages have very similar structure, regardless of the channel on which they are sent.

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]

    The evolution process of the CDMA standards is roughly divided into the following stages :

   CdmaOne namely, IS-95A and IS-95B It mainly supports the voice service, belonging to 2G communications.

   cdma2000 1X: It can support both voice and data services. The max. Data rate can reach 153 kbps, belonging to 3G mobile communications.

   cdma2000 1xEV-DO: As the enhanced version of cdma2000 1X at stage 1, it supports data services, with max. forward rate being up to 2.4 Mbps.

   cdma2000 1xEV-DV: As the enhanced version of cdma2000 1X at stage 2, it supports both voice and data services, with max. data rate being up to 4 Mbps, and even higher.