TABLE OF CONTENTS IMT-2000 has defined four 3G systems, only one of which, namely, UWC-136 is based upon the time division multiple access (TDMA) scheme, while the other three- Universal Mobile Telecommunications System (UMTS) W-CDMA Frequency Division Duplex (FDD), UMTS W-CDMA Time Division Duplex (TDD), and cdma2000-use direct-sequence code division multiple access (DS-CDMA). [1]In fact, CDMA appears to be the preferred technology for wireless communications because of the many advantages it offers including, for example, the multipath diversity and soft handoff [1], [31]. The purpose of this chapter is to provide the reader with a basic understanding of the principles of wideband CDMA technology. The chapter begins with an overview of the various access technologies. It next considers a wideband CDMA system architecture and presents some technical detail of its various physical layer components.
UMTS W-CDMA FDD is a direct-sequence CDMA system with a nominal bandwidth of 5 MHz [16], [19], [20]. The second system, UMTS W-CDMA TDD, also uses CDMA with a bandwidth of 5 MHz, but now the frequency band is time shared in both directions-one half of the time, it is used for transmission in the forward direction and the other half of the time in the reverse direction. cdma2000 is a multicarrier, direct-sequence CDMA FDD system. Like cdmaOne, its first phase is expected to use a single carrier with a bandwidth of 1.25 MHz. In the second phase, it may have as many as three carriers. In this system, even...
