Institute of Electrical & Electronic Engineers
A low-rate turbo code can reduce the required average received Signal-to-Noise power Ratio (SNR) that satisfies the target BLock Error Rate (BLER) due to its high coding gain. When a low-rate turbo code is used however, Channel Estimation (CE) error becomes a bottleneck in bringing out the potential coding gain. Therefore, this paper presents the average BLER performance using Decision-Directed Channel Estimation (DDCE) for a low-rate turbo code in uplink Discrete Fourier Transform (DFT)-pre-coded Orthogonal Frequency Division Multiple Access (OFDMA). In the proposed DDCE, the authors employ soft-decision symbol estimation based on the Log-Likelihood Ratio (LLR) of an extrinsic probability at the Max-Log-MAP (maximum a posteriori probability) decoder output in addition to Reference Signals (RSs).