The spread-spectrum technique is becoming increasingly important in wireless communication systems. In this work, the main advantages of this techniques are outlined, describing its key elements, presenting important code acquisition strategies for direct sequences (DS) and frequency hopping (FH) systems, comparing various code tracking loop systems, and detailing receiver configurations based on CCD, SAW and DSP matched filters. The authors also examine system capacity issues related to the CDMA cellular network, and explain the CDMA overlay, packetized transmission in CDMA networks, and the problems of multiuser detection.