•Code-division multiple access (CDMA) is a channel access method used by various radio communication technologies. 
•CDMA  is an example of multiple access, where several transmitters can send information simultaneously over a single communication channel. This allows several users to share a band of frequencies (see bandwidth). 


                           Fig: CDMA

•All the user in a CDMA system use the same frequency and may transmit simultaneously. Unique orthogonal code is assigned to each channel in CDMA.
•for recover the signal the receiver need to know the code used by the transmitter.
•To permit this without undue interference between the users, CDMA employs spread spectrum technology and a special coding scheme (where each transmitter is assigned a code).
•channel data rate are very high. The near far CDMA receiver if an undesired user has high speed detected power as compared to the desired user.
•The technology is commonly used in ultra-high-frequency (UHF) cellular telephone systems, bands ranging between the 800-MHz and 1.9-GHz.
   

•The technology is commonly used in ultra high-frequency (UHF) cellular telephone systems, bands ranging between the 800-MHz and 1.9-GHz.