The evolution of cellular based mobile communication systems, from the first generation (analogue) to the second generation (digital), has been made possible by solving many technical issues along the way. Efforts to develop a global standard for providing high-speed, high quality multimedia services have crystallised in the form of the third generation (3G) systems under the IMT 200 standard.The world's first 3G system has been implemented by Japan based on the latest research results and other countries are expected to follow from 2002 onwards. 3G systems are expected to bring about radical socio-economic and cultural changes that would affect people around the world.This volume reviews in detail the basic technologies applied to W-CDMA, a standard 3G mobile communications technology. The focus is to explain in layman's language the technologies that will play an important part in future developments, with reference to the latest research results.