4

Orthogonal Frequency Division Multiple Access

The technique used for radio transmission and reception in LTE is known as orthogonal frequency division multiple access (OFDMA). OFDMA carries out the same functions as any other multiple access technique, by allowing the base station to communicate with several different mobiles at the same time. However, it is also a powerful way to minimize the problems of fading and inter-symbol interference that we introduced in Chapter 3. In this chapter, we will describe the basic principles of OFDMA, and show how it is applied to a mobile cellular network. We will also cover a modified radio transmission technique, known as single carrier frequency division multiple access (SC-FDMA), which is used for the LTE uplink.