OFDMA LTE

Modulation is a process of mixing signals with a sinusoid to produce a new form of signals . The newly produced signal has certain benefits over an un-modulated signal. Mixing of low-frequency signal with a high-frequency carrier signal is called Modulation.

Orthogonal frequency-division multiplexing (OFDM), is a frequency-division multiplexing (FDM) scheme used as a digital multi-carrier modulation method . OFDM meets the LTE requirement for spectrum flexibility and enables cost-efficient solutions for very wide carriers with high peak rates.

This is the most exciting time in the mobile industry since the switchover from analog to digital back in the early 1990s. LTE represents a paradigm shift from hybrid voice and data networks to data-only networks.

LTE is based on Orthogonal Frequency Division Multiplexing (OFDM) with cyclic prefix (CP) in the downlink, and on Single-Carrier Frequency Division Multiple Access (SC-FDMA) with cyclic prefix in the uplink. It supports both FDD and TDD duplex modes for transmission on paired and unpaired spectrum.

One of the LTE features introduced in Rel-12 is the support for higher order modulation , that is 256QAM for DL data transmission to enhance the spectral efficiency and the system throughput.

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

LTE devices use QPSK, 16QAM and 64QAM to modulate data and control information. The eNodeB supports all of these modulation techniques for the Down Link direction.