Adaptive Subcarriers Grouping Algorithm for SC-FDMA Systems

A new adaptive subcarrier grouping scheme is proposed to maximize capacity of single-carrier FDMA (SC-FDMA) system. In OFDM system, the SNR of each subcarrier is dependent on the frequency selective channel fading. While in SC-FDMA system, the SNR of each symbol is of the same value. Theoretical analysis shows that the SNR of the received SC-FDMA symbol is dominated by some few deepest fading subcarriers. With the sacrifice of not using these subcarriers, the whole system performance can be significantly improved. This characteristic inspires us to propose a new algorithm to maximize overall system capacity. Different from the conventional adaptive power allocation method, we only need to decide whether to use some of the deepest fading subcarrier by our proposed adaptive grouping algorithm, and indicate grouping decision to the receiver. Simulation results show that the capacity improved by our method compared with the conventional SC-FDMA system. The average grouping information is very small, and the indication overhead is negligible compared with the whole system capacity. The PAPR is increased slightly. Our method provides a flexible tradeoff between the system performance and PAPR.