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What is LTE OFDM?
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.
How does OFDM modulation work?
OFDM is a form of multicarrier modulation. An OFDM signal consists of a number of closely spaced modulated carriers. As a result when signals are transmitted close to one another they must be spaced so that the receiver can separate them using a filter and there must be a guard band between them.
Which modulation scheme is used in LTE?
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.
How does the LTE OFDM modulator block work?
The LTE OFDM Modulator block implements an algorithm for modulating LTE resource grid samples specified by LTE standard TS 36.212 [1]. The block uses an orthogonal frequency-division multiplexing (OFDM) mechanism in its operation and converts the resource grid input samples to an equivalent time-domain signal output.
How is OFDM used in LTE downlink transmitter?
The block uses an orthogonal frequency-division multiplexing (OFDM) mechanism in its operation and converts the resource grid input samples to an equivalent time-domain signal output. OFDM is effective for communication over channels with high-frequency selectivity and is widely used in the development of the LTE downlink transmitter.
What are the different types of modulation in OFDM?
Within the OFDM signal it is possible to choose between three types of modulation for the LTE signal: QPSK (= 4QAM) 2 bits per symbol. 16QAM 4 bits per symbol. 64QAM 6 bits per symbol.
Why do we need higher order modulation for LTE?
Higher order modulation is used to achieve the higher data rates: the modulation order being determined by the signal quality. The use of OFDM is a natural choice for LTE. While the basic concepts of OFDM are used, it has naturally been tailored to meet the exact requirements for LTE.