Fundamentals of LTE

Chapter 4. Frequency Domain Multiple Access: OFDMA and SC-FDMA

The multiple access strategy is perhaps the defining choice of a cellular communication system. Previous generations of cellular systems have been popularly referred to simply as “FDMA”—First Generation (1G), notably AMPS—followed by “TDMA”—2G GSM or IS-54—and then “CDMA” for 2G IS-95 (Qualcomm) and 3G WCDMA.¹ LTE evolved from the 3G W-CDMA standards body but does not use CDMA. Rather, LTE employs two different multiple access approaches, both of which are effectively hybrids of TDMA and FDMA adapted to multicarrier modulation. In the downlink LTE utilizes Orthogonal Frequency Division Multiple Access (OFDMA), while in the uplink Single-Carrier Frequency Division Multiple Access ...