What is the benefit of SC-FDMA compared to OFDMA?

SC- FDMA has a lower PAPR and lower sensitivity to carrier frequency errors while OFDMA provides better frequency diversity resulting in better immunity against multipath fading.

Why we are using SC-FDMA in LTE uplink instead of OFDMA?

SC-FDMA is preferred for LTE uplink mainly due to its advantage of having low peak-to-average power ratio (PAPR) during signal transmission. It is found that by increasing spreading factor symbol error rate is reduced for SC-FDMA system and for spreading factor of 64 for SNR=20 dB, SER is of the order of 10 -4 .

What is subcarrier mapping?

Sub-carrier mapping is one of the major considerations for LTE as multiple mobile terminals i.e. users are assigned by partitioned subcarriers in OFDMA system. In LTE uplink a subsets of subcarriers are used to transmit its own data.

Why LTE uses OFDMA for DL and SC-FDMA for UL?

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

Why SC-FDMA is single carrier?

SC-FDMA (Singe Carrier FDMA) presents the benefit of a single carrier multiplexing of having a lower Peak-to-average Power Ratio. On SC-FDMA before applying the IFFT the symbols are pre coded by a DFT (Discrete Fourier Transform). This way each subcarrier after de IFFT will contain part of each symbol.

Why is SC-FDMA?

SC-FDMA was chosen since it combines the low PAPR techniques of single-carrier transmission systems, such as GSM and CDMA, with the multipath resistance and flexible frequency allocation of OFDMA. A mathematical description of an SC-FDMA symbol in the time domain is given in 36.211 [6] sub-clause 5.6.

What is a subcarrier frequency?

A subcarrier is a sideband of a radio frequency carrier wave, which is modulated to send additional information. Examples include the provision of colour in a black and white television system or the provision of stereo in a monophonic radio broadcast.

What is subcarrier spacing in LTE?

In LTE, the channel spacing is 15 kHz. The symbol period therefore is 1/15 kHz = 66.7 µs. The high-speed serial data to be transmitted is divided up into multiple slower streams, and each is used to modulate one of the subcarriers. A 20-MHz channel might use 1024 carriers.

How does SC-FDMA work?

SC-FDMA is a hybrid modulation scheme that combines the low peak-to-average ratio (PAR) of traditional single-carrier formats such as GSM with the multipath resistance and in-channel frequency scheduling flexibility of orthogonal frequency-division multiplexing (OFDM).

What is the difference between OFDM and SC-FDMA?

OFDMA transmits 4 qpsk symbols in parallel, one data symbol per subcarrier. From the figure it is imperative that OFDMA is multi-carrier system with one data symbol carried over by one subcarrier; while SC-FDMA is a single carrier system where in each qpsk symbol is carried by one much wider bandwidth subcarrier.

What is the difference between SC-FDMA and OFDMA?

• From the figure it is imperative that OFDMA is multi-carrier system with one data symbol carried over by one subcarrier; while SC-FDMA is a single carrier system where in each qpsk symbol is carried by one much wider bandwidth subcarrier. Refer difference between SC vs OFDM page to understand concepts of Single Carrier (SC) vs OFDM.

Which is Single Carrier Division Multiple Access ( SC-FDMA )?

Single Carrier Frequency Division Multiple Access (SC-FDMA) is a promising technique for high data rate uplink communication and has been adopted by 3GPP for it next generation cellular system, called Long-Term Evolution (LTE). SC-FDMA is a modified form of OFDM with similar throughput performance and complexity.

Which is better, OFDM or single carrier FDMA?

The main advantage of OFDM, as is for SC-FDMA, is its robustness against multipath signal propagation, which makes it suitable for broadband systems. SC-FDMA brings additional benefit of low peak-to-average power ratio (PAPR) compared to OFDM making it suitable for uplink transmission by user-terminals. 3GPP Long Term Evolution

Which is better for broadband CDMA or SC-FDMA?

The major problem in extending GSM TDMA and wideband CDMA to broadband systems is the increase in complexity with the multipath signal reception. The main advantage of OFDM, as is for SC-FDMA, is its robustness against multipath signal propagation, which makes it suitable for broadband systems.