What is CDMA ?
The term “CDMA” (Code Division Multiple Access) refers to both a spread spectrum technique and a cellular standards. Initially it was restricted to the armed forces, this technology was commercially launched in 1995.
How it Works?
- Code: It refers to the string of binary sequence that the transmitter and the receiver share. This code encodes the information into a low frequency signal before it is transmitted over a channel. This same code is used by the receiver to decode the information. The receiver gets the code with the help of the nearest base station.
- Division: In CDMA a single channel is divided into numerous slots which can be used by multiple users. This is possible because of the use of unique code.
- Multiple Accesses: Due to code based communication, multiple users can communicate and access the same channel simultaneously without any undesirable interference and loses.
Characteristics of CDMA
- The goal of CDMA is to break up a finite radio frequency so that multiple users can access it at the same time.
- Through randomization of frequencies, CDMA divides the radio frequency spectrum to share the space for multiple users using a code to accomplish the multiplexing instead of time or frequency division.
- This ability to use codes to divide up the signal provides CDMA with a great advantage over GSM and other wireless technologies because it can support more users on the available bandwidth.
- CDMA networks have greater range and clarity than GSM.
- However, it is more difficult for users to switch phones and carriers, since subscriber information is programmed directly into the phone rather than on a SIM card.
- International roaming is also not possible, since CDMA has not been implemented in many countries.