BER Performance of Joint THP/pre-FDE

Abstract

Abstract-Recently, frequency-domain equalization (FDE) based on the minimum mean square error (MMSE) criterion has been attracting much attention to overcome the frequency-selective fading channel. The bit error rate (BER) performance of singlecarrier (SC) transmission is significantly improved by using MMSE-FDE by obtaining the frequency-diversity gain while suppressing the inter-symbol interference (ISI). However, the residual ISI after MMSE-FDE limits the performance improvement. Recently, we have proposed a joint use of Tomlinson-Harashima precoding (THP) and FDE reception (joint THP/FDE) to suppress the residual ISI. However, joint THP/FDE requires the channel state information (CSI) at both the transmitter and receiver. In this paper, we replace FDE reception by pre-FDE and propose joint THP/pre-FDE that requires the CSI at the transmitter only, while providing almost the same BER performance as joint THP/FDE.

Performance of joint MMSE-THP/Pre-FDE for single-carrier transmissions in a frequency-selective channel

“…(10) that the transmit signal block (d+2Mz t ) goes through the pre-equalization represented by B and passes through the equivalent channel L. In [10], B=L is used. In this case, Eq.…”

“…QPSK or 16QAM data modulation is used. We consider the pre-FDE based on the equal gain combining (EGC) criterion [10] for joint THP/pre-FDE. FFT block size N c =128 and GI length N g =16 are assumed.…”

“…In [10], we proposed a joint Tomlinson-Harashima precoding (THP) and pre-FDE (called joint THP/pre-FDE) to remove the residual ISI. However, it was found that the use of joint THP/pre-FDE is effective only for high level data modulation, e.g., 16QAM and 64 QAM.…”

Performance improvement of joint THP/pre-FDE with lattice reduction using LLL-algorithm

“…The received signal power depends on the diagonal elements of a lower triangular matrix B, obtained by LQ-decomposition of the equivalent channel matrix. As shown in [10], since the equivalent channel matrix is represented by a circulant matrix, the amplitude of the diagonal element of B closer to lower right position drops. This degrades the BER performance achievable with joint THP/pre-FDE.…”

“…A simpler mobile terminal is desirable. We proposed joint THP/frequency-domain preequalization (pre-FDE) (joint THP/pre-FDE) [10] for downlink data transmission. Since pre-FDE is carried out at the transmitter, joint THP/pre-FDE can alleviate the complexity problem of mobile terminals and suitable for downlink applications.…”