Code Division Multiple Access (CDMA)

CDMA is stands for Code Division Multiple Access. The CDMA technology spreads the information contained in a particular signal of interest over a much greater bandwidth than the original signal. This technology offers a number of benefits to the cellular operators as well as to the subscribers.

Following are the benefits of CDMA

• Capacity increases of 8 to 10 times that of an analog system
• Improved call quality with better and more consistent sound as compared to system or near-wire line quality voice service.
• Simplified system planning through the use of the same frequency in every sector of every cell.
• Reduced installation time, error rates, inventory of components, maintenance and many other related benefits.
• Enhanced privacy
• Improved coverage characteristics allowing for possibility of fewer cell sites or minimum number of fixed radio sites
• Increased connectivity time for portables
• Bandwidth available on demand
• Near-universal geographical coverage
• Low equipment cost, both subscriber stations and fixed plant.

CDMA falls under the category of spread-spectrum technology a family of digital communication techniques used in military applications for many years. The basic principle of behind the technology is the user of noise like carrier waves and bandwidths much wider than those used for point to point communication.

There are two philosophies behind the evolution of CDMA that has been derived from military application viz.
-> That the enemy efforts of jam communications system should be prevented by use of anti-jam of AJ techniques.
-> That the enemy should not even know that communication was even taking place, by use of concept sometimes called low probability of intercept (LPI).