The relation of sub-carrier and FDMA

1. What is subcarrier frequency?
2. What is the advantage of Single Carrier FDMA comparing to OFDMA?
3. What is the difference between OFDMA and SC-FDMA?
4. Why SC-FDMA is used in uplink?

What is subcarrier frequency?

A subcarrier is a secondary modulated signal frequency modulated into the main frequency (the carrier) to provide an additional channel of transmission. It allows for a single transmission to carry more than one separate signal.

What is the advantage of Single Carrier FDMA comparing to OFDMA?

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.

What is the difference between OFDMA and SC-FDMA?

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 SC-FDMA is used in uplink?

SC-FDMA is preferred for LTE uplink mainly due to its advantage of having low peak-to-average power ratio (PAPR) during signal transmission. The performance of SC-FDMA depends on modulation scheme used for it.