A sub-block orthogonal single carrier frequency domain equalization system in fast Rayleigh fading channel

Abstract

In this paper, we analyze the frequency domain linear equalization (FDLE) of single carrier block transmission (SCBT) systems under fast fading channel. First, we propose a new approximating model in which the channel is assumed to be static in sub-blocks vary each other. Based on this model, we derive a new 2-orthogonal-sub-blocked frequency domain equalization method. Then, we derive the conditions of the channel under which the equalization method can be applied to the 2-orthogonal-sub-blocked systems. Simulation demonstrates that the proposed method can improve the anti-Doppler ability of SC-FDLE and at the same time keep its high efficiency and low complexity. CitationLiu R, Gao X Q, Wang W J. A sub-block orthogonal single carrier frequency domain equalization system in fast Rayleigh fading channel.

MMSE SQRD based SISO detection for coded MIMO-OFDM systems

“…The other dominant computation of MMSE SQRD based SISO detection per transmit symbol involves performing soft interference cancellation with complexity O(n T n R ), computing the probabilities P (x j (k) = x|L pos j (k)) and P (x i (k) = x|L apr i (k)) with complexity O(M c 2 Mc ), computing the a posteriori LLR vector L pos j (k) with complexity O(M c 2 Mc ), and computing the estimate with complexity O(n R + n T ). Hence, the overall complexity of the proposed detection per turbo iteration is in the order of O(n 3 T…”

“…The number of the antennas is denoted by n. Since the operations required by the soft demodulation and soft modulation are the same for the two detections, they are not included in the following analysis for simplicity. At each iteration in the proposed detection, the MMSE SQRD at each frequency requires about 4n 3 + 1/2n 2 + 1/2n flops, computingx(k) requires about 3n 2 + n + 3 flops, and computing the symbol estimatesx i (k) and their error variances requires about 3 2 n 2 + 29 2 n + 1 flops. By adding the three components together, we get the number of total flops per iteration at each frequency in the proposed detection, it is 4n 3 + 5n 2 + 16n + 4.…”

“…MIMO wireless technology offers increased spectral efficiency and improved link reliability via spatial-multiplexing and diversity, respectively [1,2]. Meanwhile, OFDM signal transmission is an approach that efficiently suppresses the frequency selective fading [3]. Specifically, by converting a MIMO frequency selective channel to a set of flat fading channels, OFDM modulation simplifies channel equalization significantly at the receiver [4,5].…”

An Estimated δ-Based Iterative Block Decision Feedback Equalization in SC-FDE System

“…Common frequency domain equalization algorithms can be divided into two categories: linear equalization and nonlinear equalization. The equalization in which the decision output is not used for feedback is called linear equalization [9,10], such as the classic zero-force equalization (ZF) and minimum mean square error (MMSE) equalization. ZF equalization directly uses the inverse matrix of the channel impulse response matrix as the filter coefficient, which is small in computation and low in complexity.…”

From frequency domain to time domain: performance analysis on cyclic prefixed multi-user single-carrier transmission

“…Consequently, the computational complexity to realize the optimal TDE is exponential to the block size and becomes prohibitively high. By contrast, frequency domain equalization (FDE) [13,14] uses one-tap equalization on each frequency, its computational complexity increases linearly with the block size and thus is much lower than TDE. Also, when multiple antennas are available at the receiver side, multiple access interference can also be suppressed by frequency domain weight control.…”