Does LTE use OFDM?

LTE uses OFDM as the basic signal format – OFDMA in the downlink and SC-FDMA in the uplink with various modulation formats. OFDM forms the basic signal format used within 4G LTE. Higher order modulation is used to achieve the higher data rates: the modulation order being determined by the signal quality.

What is windowing in OFDM?

A very similar technique is known as Windowed-OFDM (W-OFDM) in which windowing is applied in a manner that the window overlaps with the complete OFDM symbol as well as the CP and the cyclic suffix. Moreover, the window amplitude is −3 dB at the start and end of the OFDM symbol.

What is OFDM in networking?

Orthogonal Frequency Division Multiplexing (OFDM) is a digital multi-carrier modulation scheme that extends the concept of single subcarrier modulation by using multiple subcarriers within the same single channel. OFDM is based on the well-known technique of Frequency Division Multiplexing (FDM).

Why is OFDM not used in uplink?

OFDMA is used on the downling, but since it presents a high Peak-to-average Power Ratio it is not possible to use it on the uplink.

Why PAPR is high in OFDM?

The PAPR is rather high in OFDM due to the linear combination of many (pseudo-random) QAM symbols in the IFFT operation (5.3). Hence, due to the central limit theorem, some output OFDM symbols will have very large PAPR.

How do I choose a window function?

To choose a window function, you must estimate the frequency content of the signal. If the signal contains strong interfering frequency components distant from the frequency of interest, choose a smoothing window with a high side lobe roll-off rate.

What is the highest modulation scheme that is used in LTE?

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.