Code Division Multiple Access

An alternative to frequency division and time division multiple access schemes is provided by code division multiple access (CDMA), which permits multiple users to transmit simultaneously over a channel while occupying the same frequency band. This is effected by assigning a unique code or signature to each user. As we will see, CDMA offers several advantages. Various schemes have been devised to generate the codes; this chapter will introduce the fundamentals of direct-sequence spread spectrum CDMA (DS-CDMA).