Showing papers on "SC-FDE published in 2019"
TL;DR: This paper considers the downlink transmission of NOMA schemes combined with single-carrier (SC) signals and presents a multi-antenna transmission technique that is compatible with highly efficient power amplifiers without requiring any pre-processing.
12 citations
TL;DR: This work studies analytically the performance of mMIMO systems based on SC-FDE schemes employing low-complexity, iterative FDE receivers, and low-resolution ADCs and shows that the performance degradation associated to low- resolution ADCs can be tolerable.
Abstract: Massive multiple-input multiple-output (mMIMO) systems are very important for 5G since they are one of the main enablers of the targeted huge capacity gains. On the other hand, the power consumption at the mobile terminals should be as low as possible, making single-carrier waveforms, such as single carrier with frequency-domain equalization (SC-FDE), particularly interesting, since the transmit signals can have a low peak-to-average power ratio (PAPR), allowing a highly efficient power amplification. However, the combination of mMIMO systems with SC-FDE modulations gives rise to implementation difficulties at the receiver side. On one hand, the equalization procedure should avoid matrix inversions, but this might lead to performance degradation. On the other hand, low-resolution analog-to-digital converters (ADCs) should be employed in each receive branch to reduce the implementation complexity, which might lead to severe nonlinear distortion effects. In this work, we study analytically the performance of mMIMO systems based on SC-FDE schemes employing low-complexity, iterative FDE receivers, and low-resolution ADCs. It is shown that the performance degradation associated to low-resolution ADCs can be tolerable if the number of receive antennas is larger than the number of transmit antennas, even when low-complexity FDE receivers are employed.
11 citations
TL;DR: A new receiver for joint carrier frequency offset (CFO) and channel estimation on single-carrier modulations with frequency-domain equalization along with SWIPT implementation for EH by using the pilot signal.
Abstract: Radio-frequency energy harvesting (EH) is one of the enabling technologies for the next-generation wireless communication systems. EH techniques are specifically used to improve the energy efficiency of the system. Recently, the simultaneous wireless information and power transmission (SWIPT) protocol is adapted for EH. In this paper, we design a new receiver for joint carrier frequency offset (CFO) and channel estimation on single-carrier modulations with frequency-domain equalization along with SWIPT implementation for EH by using the pilot signal. The pilot signal is a highly energized signal, which is superimposed with the information signal. The superimposed signal is used not only to transmit power for EH purposes but also to estimate the CFO and channel conditions. The receiver is designed to accommodate the strong interference levels in the channel estimation and data detection. The proposed scheme offers a flexible design method and efficient resource utilization. We validate our analytical results using simulations.
9 citations
08 Sep 2019
TL;DR: A novel, mutual-information dependent learning cost function is proposed, suited to turbo detectors, and through learning, the detection performance of the deep EP network is optimized.
Abstract: This paper analyzes some emerging techniques from the broad area of Bayesian learning for the design of iterative receivers for single-carrier transmissions using bit-interleaved coded-modulation (BICM) in wideband channels. In particular, approximate Bayesian inference methods, such as expectation propagation (EP), and iterative signal-recovery methods, such as approximate message passing (AMP) algorithms are evaluated as frequency domain equalizers (FDE). These algorithms show that decoding performance can be improved by going beyond the established turbo-detection principles, by iterating over inner detection loops before decoding. A comparative analysis is performed for the case of quasistatic wideband communications channels, showing that the EP-based approach is more advantageous. Moreover, recent advances in structured learning are revisited for the iterative EP-based receiver by unfolding the inner detection loop, and obtaining a deep detection network with learnable parameters. To this end, a novel, mutual-information dependent learning cost function is proposed, suited to turbo detectors, and through learning, the detection performance of the deep EP network is optimized.
9 citations
TL;DR: Numerical simulation results show that the BER performance of MIMO-SC-FDE in Doppler distorted UWA channel environment is improved with acceptable increase of computational complexity, and the proposed partial FFT demodulation with interference rejection combining (IRC) algorithm has the ability to simultaneously suppress signal distortion.
Abstract: Multi-input multi-output single carrier frequency domain equalization (MIMO-SC-FDE) has been extensively researched in the past years as a technique to realize high data-rate underwater acoustic (UWA) communication. However, it will suffer from severe inter-symbol interference(ISI), frequency offset and co-channel interference (CoI) over Doppler distorted UWA channels. In order to solve the above problems introduced by UWA channels in MIMO communication scenario, partial FFT demodulation with interference rejection combining (IRC) algorithm is proposed in this letter. Compared with previous works, the proposed algorithm has the ability to simultaneously suppress signal distortion brought by ISI, Doppler shift and CoI by frequency domain processing. Numerical simulation results show that the BER performance of MIMO-SC-FDE in Doppler distorted UWA channel environment is improved with acceptable increase of computational complexity.
6 citations
TL;DR: The results show that the proposed ranging method can achieve unbiased estimate and its root mean square errors will reach the order of centimeter at medium-to-high signal- to-noise ratio region in flat-fading channels, whereas the observed performance degradation in frequency selective channel can be mitigated by using equalized oversampled signals.
Abstract: Ground-based positioning systems are necessary as the conventional satellite-based systems suffer from weak received signals. In this paper, we proposed a precise ranging method in single-carrier frequency domain equalization (SC-FDE) system using the amplitude nonlinearity of oversampled signals. A new pattern of the preamble and the unique word was designed for SC-FDE system, where the preamble can be exploited in correlation-based timing algorithm to obtain impulse-like timing metric. Combining with the coarse timing procedure, we proposed a fine ranging method relying on the oversampled signals in SC-FDE receiver employing Qth-power nonlinearity, and then analyzed its estimation mean and variance. The extensive simulations were conducted to validate the proposed method with distinct modulation schemes, rolling-off factors, block lengths, and nonlinearity factors. The results show that the proposed ranging method can achieve unbiased estimate and its root mean square errors will reach the order of centimeter at medium-to-high signal-to-noise ratio region in flat-fading channels, whereas the observed performance degradation in frequency selective channel can be mitigated by using equalized oversampled signals.
6 citations
TL;DR: A priori information aided scheme that effectively improves the reconstruction of probability, thereby improving the accuracy of channel estimation, meanwhile sacrificing less spectral efficiency is proposed.
Abstract: The channel of wireless broadband communication system usually features time domain sparsity. The channel estimation of single carrier frequency domain equalization (SC-FDE) system was modeled as compressive sensing (CS)-based reconstruction of sparse signal. Matching pursuit algorithms based on greedy search were adopted to reconstruct channel information. Under the premise of reduced reference signal overhead, the system reliability can be effectively enhanced. This paper proposes a priori information aided scheme. By inserting the cyclic prefix of the first training sequence to a SC-FDE transmission frame, which is used as guard interval, the priori information including more accurate channel length and sparsity can be obtained with inter-block-interference (IBI)-free training sequence. The proposed scheme shows obvious superiority in slow fading channels. It effectively improves the reconstruction of probability, thereby improving the accuracy of channel estimation, meanwhile sacrificing less spectral efficiency.
5 citations
TL;DR: In this article, a performance analysis of widely linear (WL) equalizers for single carrier systems using frequency domain equalization (SC-FDE) under multiple independent interferences is presented, and the expressions of the mean square error (MSE) and bit error rate (BER) for linear and WL equalizers in their regular and iterative versions for this scenario were derived.
Abstract: In this paper, a performance analysis of widely linear (WL) equalizers for single carrier systems using frequency domain equalization (SC-FDE) under multiple independent interferences is presented. In this context, the expressions of the mean square error (MSE) and bit error rate (BER) for linear and WL equalizers in their regular and iterative versions for this scenario were derived. It was seen that the results obtained with these expressions match the simulated ones. They also show that the performance of the WL equalizers is better when compared to their linear versions regardless of the number of interferences.
4 citations
Journal Article•
TL;DR: In the FPGA implementation of the timing synchronization algorithm, the sliding window accumulation, quantization processing and amplitude reduction techniques are adopted to reduce the complexity in the implementation of FPDA.
Abstract: The single carrier frequency domain equalization (SC-FDE) technology is an important part of the broadband wireless access communication system, which can effectively combat the frequency selective fading in the wireless channel. In SC-FDE communication system, the accuracy of timing synchronization directly affects the performance of the SC-FDE system. In this paper, on the basis of Schmidl timing synchronization algorithm a timing synchronization algorithm suitable for FPGA (field programmable gate array) implementation is proposed. In the FPGA implementation of the timing synchronization algorithm, the sliding window accumulation, quantization processing and amplitude reduction techniques are adopted to reduce the complexity in the implementation of FPGA. The simulation results show that the algorithm can effectively realize the timing synchronization function under the condition of reducing computational complexity and hardware overhead.
3 citations
TL;DR: The physical layer security issues of MIMO with Singular Value Decomposition (SVD) schemes, employed along with Single-Carrier with Frequency-Domain Equalization (SC-FDE) techniques are studied and it is shown that the higher the distance between the eavesdropper and the transmitter or receiver, the higherThe secrecy rate.
Abstract: Multi-Input, Multi-Output (MIMO) techniques are seeing widespread usage in wireless communication systems due to their large capacity gains. On the other hand, security is a concern of any wireless system, which can make schemes that implement physical layer security key in assuring secure communications. In this paper, we study the physical layer security issues of MIMO with Singular Value Decomposition (SVD) schemes, employed along with Single-Carrier with Frequency-Domain Equalization (SC-FDE) techniques. More concretely. the security potential against an unintended eavesdropper is analysed, and it is shown that the higher the distance between the eavesdropper and the transmitter or receiver, the higher the secrecy rate. In addition, in a scenario where there is Line of Sight (LOS) between all users, it is shown that the secrecy rate can be even higher than in the previous scenario. Therefore, MIMO-SVD schemes combined with SC-FDE can be an efficient option for highly secure MIMO communications.
3 citations
01 Apr 2019
TL;DR: This paper proposes a low complexity CFO estimation technique for single carrier frequency domain equalization (SC-FDE) and orthogonal frequency division multiplexing (OFDM) based Massive MIMO systems and uses pilots sent for channel estimation to estimate both the CFO and the channel, iteratively.
Abstract: Low complexity and spectral efficient carrier frequency offset (CFO) estimation in massive multiple input multiple output (MIMO) systems is a critical problem. Therefore, in this paper we propose a low complexity CFO estimation technique for single carrier frequency domain equalization (SC-FDE) and orthogonal frequency division multiplexing (OFDM) based Massive MIMO systems. In this technique, to increase the spectral efficiency, we use the pilots sent for channel estimation to estimate both the CFO and the channel, iteratively. Our analysis show that our proposed technique has better performance and lower complexity than previous techniques which utilize one pilot block for both CFO and channel estimation in massive MIMO systems.
TL;DR: This paper proposes a new space-frequency adaptive equalization method for single carrier frequency domain equalization systems that can deal with multipath interference from the highly delay-dispersive channel as well as the multiuser interference.
Abstract: In this paper, we propose a new space-frequency adaptive equalization (SFAE) method for single carrier frequency domain equalization (SC-FDE) systems that can deal with multipath interference from the highly delay-dispersive channel as well as the multiuser interference. Based on the minimum mean square error (MMSE) criterion, we derive the adaptive weights by combining the received multi-antenna signals in the frequency domain. The main computation burdens of the proposed SFAE and the conventional space-time adaptive equalization (STAE) lie in the calculation of the autocorrelation matrix R and its inversion. The autocorrelation matrix in the SFAE is exactly a block Toeplitz matrix whose calculation can be efficiently implemented by the fast Fourier transformation (FFT) and its inversion also has fast algorithms. Compared with the conventional STAE method, the proposed SFAE method has comparable interference suppression performance, but with a lower order computational complexity. Hence, the proposed SFAE should be more attractive from a practical point of view. The numerical results are provided to corroborate the proposed studies.
01 Sep 2019
TL;DR: This paper uses a low-complexity iterative frequency-domain equalizer based on the iterative block decision-feedback equalization (IB-DFE) concept for the channel equalization and an extended Kalman filter (EKF) for theChannel tracking procedure.
Abstract: In this paper we consider the use of a single- carrier with frequency-domain equalization (SC-FDE) scheme for the uplink in a cellular radio system. To cope with the doubly-selective nature of the channel we propose a receiver structure for the joint channel equalization and tracking. We use a low-complexity iterative frequency-domain equalizer based on the iterative block decision-feedback equalization (IB-DFE) concept for the channel equalization and an extended Kalman filter (EKF) for the channel tracking procedure. The tracking procedure works by, first, observing the channel through channel estimation based on training blocks and, then, by predicting the channel during data transmission. Alternatively, decision-directed channel estimation can be used also, resulting in an improved performance.
01 Sep 2019
TL;DR: This paper derives the achievable rate of single-carrier frequency domain equalizer (SC-FDE) and orthogonal frequency division multiplexing (OFDM) systems, constrained on low resolution analog to digital converters (ADCs) from an ultra-wide band millimeter wave system with a frequency selective channel.
Abstract: In this paper, we derive the achievable rate of single-carrier frequency domain equalizer (SC-FDE) and orthogonal frequency division multiplexing (OFDM) systems, constrained on low resolution analog to digital converters (ADCs). We assume that there is a full knowledge of channels at both transmitter and receiver sides. We model low resolution ADCs with an additive uniform quantization noise. We consider an ultra-wide band millimeter wave (mm-Wave) system with a frequency selective channel. The channel is based on practical results at mm-Wave frequencies. Our numerical results show that SC-FDE systems with minimum mean square error (MMSE) equalizers outperform OFDM and SC-FDE systems with zero forcing (ZF) equalizers at high signal to noise ratio (SNR) regimes. Moreover, benefits of increasing the ADCs resolution are not significant due to exponentially increment in the power consumption of ADCs.
01 Dec 2019
TL;DR: A SC-FDE scheme with partial FFT demodulation for Doppler distorted UWA communication and further extend this demodulated strategy to multiple-input-multiple-output (MIMO) communication system, that MIMO-SC-Fde.
Abstract: Although single-carrier frequency domain equalization (SC-FDE) has been extensively researched in the past year as an alternative to orthogonal frequency-division multiplexing (OFDM), it still suffers severe performance degradation in Doppler distorted underwater acoustic (UWA) channels. Recently, partial Fast Fourier Transform (FFT) demodulation has been proposed to solve the inter-carrier interference problem in OFDM. In this letter, we propose a SC-FDE scheme with partial FFT demodulation for Doppler distorted UWA communication and further extend this demodulation strategy to multiple-input-multiple-output (MIMO) communication system, that MIMO-SC-FDE. Numerical simulations are conducted to demonstrate the effectiveness of SC-FDE and MIMO-SC-FDE systems with partial FFT demodulation. The results show that the bit error ratio performances can be improved satisfactorily with the increase of the number of the intervals for both the systems.
01 Jan 2019
TL;DR: The experimental results show that the SC-FDE scheme can achieve a communication rate of 80kbps, and the bit error rate is 1.56E-2, which lays a good foundation for the subsequent study.
Abstract: Single carrier frequency domain equalization (SC-FDE) technology is applied to ultrasonic wireless communication systems. The traditional cyclic prefix (CP) is replaced by the unique word (UW) sequence for channel estimation. The signal sequence is transmitted through an acoustic-electrical conversion channel composed of two piezoelectric transducers and a metal wall. And the received signal is decoded after least squares (LS) channel estimation and minimum mean square error (MMSE) channel equalization in the frequency domain. Finally the original signal is obtained. We use two 1MHz piezoelectric pieces and a 7mm copper plate as acoustic-electrical channel. The experimental results show that the scheme can achieve a communication rate of 80kbps, and the bit error rate is 1.56E-2, which lays a good foundation for the subsequent study.
01 Feb 2019
TL;DR: It is shown that the ZF matrix is approximated by a maximum ratio combining (MRC) one in a massive MIMO case, and that the MRC matrix requires almost no computations and the degradation of the BER performance is small.
Abstract: MIMO single-carrier frequency domain equalization (SC-FDE) can achieve high data-rate uplink transmission. We need, however, weight matrices for all the frequency points which separate spatially multiplexed signals and equalize channel distortion. In this paper, we deal with zero-forcing (ZF) matrices. To obtain them, we need matrix inverse calculations, and the computational complexity is heavy when the number of frequency points is large. It is possible to reduce the amount of calculations using an interpolation technique. We calculate ZF weight matrices for a part of frequency points, and for the remaining ones, we obtain the matrices by interpolation. This technique has been investigated for MIMO OFDM systems so far. In this paper, we consider computational complexity reduction for massive MIMO SC-FDE. We examine bit error rate (BER) performance of the linear and DFT interpolations. It is shown that the interpolation techniques achieve satisfactory BER with lower computational complexity. Also, we show that the ZF matrix is approximated by a maximum ratio combining (MRC) one in a massive MIMO case, and that the MRC matrix requires almost no computations and the degradation of the BER performance is small.
15 Apr 2019
TL;DR: This paper shows that the minimum bit-error rate (BER) transceiver design for multiple-input multiple-output (MIMO) decode-and-forward (DF) relay systems employing single-carrier transmission with frequency-domain equalization can be reduced to the optimization of two equivalent point-to-point MIMO systems.
Abstract: In this paper, we consider minimum bit-error rate (BER) transceiver design for multiple-input multiple-output (MIMO) decode-and-forward (DF) relay systems employing single-carrier transmission with frequency-domain equalization (SC-FDE). The problem is formulated as the minimization of the end to-end (e2e) BER subject to a joint source and relay transmit power constraint. Since the e2e-BER is highly non-convex in terms of the complex matrix optimization variables, solving the optimization problem directly is challenging. By resorting to an upper bound on the e2e-BER and by assuming an optimal sum power budget splitting for the source and relay, we show that the problem can be reduced to the optimization of two equivalent point-to-point MIMO systems. This enables us to derive the optimal eigen-structure of the precoders and the matrix optimization problem simplifies into a convex power allocation problem involving real scalar variables. Primal decomposition is further applied to solve the resulting convex problem in a layered manner, where closed-form solutions are obtained for the inner subproblems. Simulation results are provided to confirm the BER performance of the proposed transceiver design for SC-FDE based MIMO DF relay systems.
01 Nov 2019
TL;DR: It is shown through simulations that the error performance when using the proposed widely linear structure is better when compared to the regular widely linear one and the strictly linear versions.
Abstract: In this work, we analyze the effect of channel estimation errors on the bit error rate (BER) of a novel widely linear frequency domain iterative equalizer for single carrier systems under the effect of multiple interferences. It is shown through simulations that the error performance when using the proposed widely linear structure is better when compared to the regular widely linear one and the strictly linear versions.
29 Jan 2019
TL;DR: In this article, a time domain matrix interleaved with a single carrier frequency domain equalizer (SC-FDE) is proposed to reduce the deleterious effects of impulsive noise.
Abstract: Impulsive noise is considered as one of the major source of disturbance in the state-of-the-art multicarrier (MC) communication systems. Therefore, several techniques are being constantly proposed to eliminate the effect of such noise. In this work, a time domain matrix interleaved is compiled with a single carrier frequency domain equalizer (SC-FDE) is proposed to reduce the deleterious effects of impulsive noise. A mathematical model for the proposed scheme is also presented in this paper. Simulation results show that the proposed technique superiors the interleaved multicarrier system where the proposed scheme can completely avoid the error floors not only at high signal-to-noise ratio (SNR) but also at heavily distributed impulsive noise. The bit-error-rate (BER) of the alternative proposed scheme decreases as the signal-to-noise ratio (SNR) increases whereas the BER of the standard system suffers from error-floors with a constant BER at about 10-3 for about 8 dB SNR for medium and heavily impulsive noise.
01 Dec 2019
TL;DR: This paper proposes a receiver structure for the joint channel equalization and tracking of the V2X channel and uses a low-complexity iterative frequency-domain equalizer based on the iterative block decision-feedback equalization (IB-DFE) concept for the channelequalization and an extended Kalman filter (EKF) for theChannel tracking.
Abstract: In this paper we consider the use of a single- carrier with frequency-domain equalization (SC-FDE) scheme for vehicle-to-everything (V2X) communications. To cope with the doubly-selective nature of the V2X channel we propose a receiver structure for the joint channel equalization and tracking. We use a low-complexity iterative frequency-domain equalizer based on the iterative block decision-feedback equalization (IB-DFE) concept for the channel equalization and an extended Kalman filter (EKF) for the channel tracking. The tracking procedure works by, first, observing (estimating) the channel state using training symbols and then predicting the channel state using a state-transition model during the transmission of the data symbols. Alternatively, decision-directed channel estimation also can be used, resulting in improved performance.