Lte modulation structure

The digital modulation techniques used by 4G LTE networks are Quadrature Amplitude Modulation (QAM) and Quadrature Phase Shift Keying (QPSK) . Higher QAM modulation order, larger bandwidths and superior antenna techniques (MIMO) allow LTE to offer higher data rates. LTE Advanced networks use 256 QAM.

Orthogonal Frequency Division Multiplexing (OFDM) is an efficient modulation format used in modern wireless communication systems including 5G.16 Nis 2020

Unlike LTE, 5G NR also supports CP-OFDM in the uplink direction. But LTE’s discrete Fourier transform spread OFDM (DFT-s-OFDM) uplink scheme, better known as single carrier frequency division multiplex (SC-FDMA), is still a valid access scheme and support is mandatory for any 5G terminal.

Non-orthogonal multiple access, NOMA : NOMA is one of the techniques being considered as a 5G multiple access scheme. NOMA superposes multiple users in the power domain, using cancellation techniques to remove the more powerful signal.

OFDMA is already deployed in 4G and 5G . In the world of wireless LAN, the latest Wi-Fi standard (IEEE 802.11ax) uses OFDMA for both uplink and downlink data transfer. The IEEE 802.11 standard defines the commonly used wireless LAN technologies, with 802.11ax recently being released into the marketplace.