What is OFDM and SC-FDMA in LTE?
What is OFDM and SC-FDMA in LTE?
One of the key elements of LTE is the use of OFDM (Orthogonal Frequency Division Multiplex) as the signal bearer, as well as OFDM’s associated access schemes, OFDMA (Orthogonal Frequency Division Multiple Access) and SC-FDMA (Single Carrier Frequency Division Multiple Access).
Which QAM is used in 4G?
4G LTE networks use Quadrature Amplitude Modulation (QAM) and Quadrature Phase Shift Keying (QPSK). LTE Advanced networks employ 256-QAM, but the original LTE release in 2009 only supported 16 and 64-QAM.
What modulation scheme does 5G use?
Orthogonal Frequency Division Multiplexing (OFDM) is an efficient modulation format used in modern wireless communication systems including 5G.
Why LTE uses Ofdma for DL and SC-FDMA for UL?
In LTE, the OFDMA is used as downlink and SCFDMA as uplink modulation schemes; with OFDM as the basic building block. OFDMA is used for achieving high spectral efficiency in communication system; whereas, SC-FDMA for uplink multiple access scheme in LTE system.
What is modulation in LTE?
Modulation is the process of varying the properties of a carrier signal such as frequency, phase and amplitude with a modulating signal that contains the actual information to be transmitted. A modulator does the modulation of a signal and a demodulator does exactly the reverse of modulation.
What is MCS in LTE?
MCS (Modulation and Coding Scheme) defines how many useful bits can be transmitted per Resource Element (RE). MCS depends on radio link quality. The better quality the higher MCS and the more useful data can be transmitted.
What is F OFDM?
f-OFDM stands for ‘Filtered OFDM’. This term has confused me so much. Basically most of 5G waveform candidates use a kind of filter. As you see here, in f-OFDM.. a band can be devided into multiple subbands. Each of the bands can have different bandwidth.
What is modulation order in LTE?
LTE UE would use MCS (Modulation Coding Scheme) index for modulation order for both PDSCH and PUSCH. If modulation order is 2, 4 (2 powered by 2) different digit values come and it turns out QPSK in digital modulation scheme.
What is sub carrier spacing?
Subcarrier spacing is equal to the reciprocal of the symbol time. As a result of the longer symbol time, the subcarrier size and spacing decreases from 312.5 KHz to 78.125 KHz. The narrow subcarrier spacing allows better equalization and therefore enhanced channel robustness.
What is a modulation technique?
Modulation is the process of converting data into electrical signals optimized for transmission. Modulation techniques are roughly divided into four types: Analog modulation, Digital modulation, Pulse modulation , and Spread spectrum method.
How many types of modulation are there in LTE?
Within the OFDM signal it is possible to choose between four types of modulation for the LTE signal: The exact LTE modulation format is chosen depending upon the actual conditions. When there is a sufficient signal to noise ratio the higher order modulation format can be used and more data can be transferred.
What is the basic signal format used in LTE?
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.
What is the frame structure of LTE?
LTE Frame structure. As mentioned as per topologies, TDD and FDD there are two frame structures viz. type-1 and type-2 LTE frame structure. Total Frame duration is about 10ms. There are total 10 subframes in a frame. Each subframe composed of 2 time slots. Type 1 is used as LTE FDD frame structure.
What does it take to demodulate LTE signals?
Demodulating LTE signals requires a thorough understanding of the LTE signal structure as well as advanced algorithms to extract information from the raw signal. The complexity of the standard and the algorithms and concepts involved make developing an LTE product very challenging.
