CDMA (Code Division Multiple Access) is a digital cellular technology that uses spread-spectrum techniques. Unlike competing systems, such as GSM, that use TDMA, CDMA does not assign a specific frequency to each user. Instead, every channel uses the full available spectrum. Individual conversations are encoded with a pseudorandom digital sequence. CDMA is actually a military technology first used during World War II by the English allies to foil German attempts at jamming transmissions. Interestingly enough, the allies transmitted over several frequencies, not one, making it difficult for the Germans to pick up the complete signal. Because Qualcomm Inc. created communications chips for CDMA technology, it was privy to the classified information. Eventually as more of the information became public, Qualcomm claimed patents on the technology and became the first to commercialize it. Figure 4.1 depicts a graphical perspective of how CDMA functions in conversations.

The architecture of CDMA is such that multiple conversations are transpiring at the same time, sharing the same frequency as other CDMA conversations. The CDMA systems decipher each of the conversations so that each listener understands whom he or she is listening to. In Figure 4.1, imagine that all of the people in the room are all multilingual, and only the people talking to each other understand what the other person is saying, because they are speaking the same language. Advantages of CDMA over analog systems include:

  • Capacity gains of 8 to 10 times that of AMPS analog systems
  • Improved call quality, with better and more consistent sound as compared to AMPS systems
  • Simplified system planning through the use of the same frequency in every sector of every cell
  • Enhanced privacy through the spreading of voice signals
  • Improved coverage characteristics, allowing for fewer cell sites
  • Increased talk time for portables

Taken From : Enterprise Guide to Gaining Business Value from Mobile Technologies

Filed under: Generate Money

Like this post? Subscribe to my RSS feed and get loads more!