On Soft Decision Value Calculation for Linear-Dispersion Codes with SC-FDMA

Abstract

The capability of error correction codes is largely dependent on the calculation of soft decision values. In this letter, linear-dispersion (LD) code is applied to single-carrier frequency-division multiple access (SC-FDMA) and the closedform expression of soft decision values is derived. It is shown that the calculation of soft decision values generally depends on both time and space within an SC-FDMA symbol, as opposed to single-antenna transmission. In addition, a sufficient condition to guarantee the independence from time and space is presented. Index Terms-SC-FDMA, DFTS-OFDM, linear dispersion code, MIMO, soft decision value, LLR, MMSE.

Impact of Gain/Phase Variation on MIMO Precoder Selection for LTE UL

“…This is consistent with the fact that the TD SINR remains constant within an SC-FDMA symbol, i.e., it is independent of the time index n [4]. More importantly, (8) implies that the MIMO precoding maximizing the FD SINR tends to maximize the TD SINR, especially, in slightly-dispersive channels.…”

“…Here minimum mean square error (MMSE) equalization is used, which consists of frequency-domain (FD) MMSE equalization and inverse DFT (IDFT) despreading [4]. Defining the noise covariance matrix of the k-th subcarrier as…”