Showing papers on "SC-FDE published in 2017"

Demonstration of 60 GHz millimeter-wave short-range wireless communication system at 3.5 Gbps over 5 m range

Abstract: Millimeter-wave communication has received considerable attention for use in new-generation broadband wireless communication because of the scarcity of microwave band spectrum resources. The unlicensed frequency band at 60 GHz is suitable for indoor short-range broadband communication. In this paper, we introduce a 60 GHz millimeter-wave short-range wireless communication demo system adhering to the IEEE 802.11ad standard and targeting high-definition video streaming transmission. The system uses single-carrier transmission with frequency-domain equalization. The hardware prototype consists of a 65-nm CMOS radio-frequency front-end and a baseband transceiver for the physical layer functions. Important baseband technologies such as carrier synchronization, phase noise compensation, frequency-domain equalization, and low-density parity-check decoding based on probability calculation are also discussed. The system performance is demonstrated in an experiment on high-definition video transmission, where a data rate of 3.52 Gbps is achieved with a quadrature phase-shift keying signal over a distance of 5.109 m.

Single Carrier with Frequency Domain Equalization for Synthetic Aperture Underwater Acoustic Communications

Abstract: Phase-coherent underwater acoustic (UWA) communication systems typically employ multiple hydrophones in the receiver to achieve spatial diversity gain. However, small underwater platforms can only carry a single transducer which can not provide spatial diversity gain. In this paper, we propose single-carrier with frequency domain equalization (SC-FDE) for phase-coherent synthetic aperture acoustic communications in which a virtual array is generated by the relative motion between the transmitter and the receiver. This paper presents synthetic aperture acoustic communication results using SC-FDE through data collected during a lake experiment in January 2016. The performance of two receiver algorithms is analyzed and compared, including the frequency domain equalizer (FDE) and the hybrid time frequency domain equalizer (HTFDE). The distances between the transmitter and the receiver in the experiment were about 5 km. The bit error rate (BER) and output signal-to-noise ratio (SNR) performances with different receiver elements and transmission numbers were presented. After combining multiple transmissions, error-free reception using a convolution code with a data rate of 8 kbps was demonstrated.

Compensation of Transmitter I/Q Imbalance in Millimeter-Wave SC-FDE Systems

Abstract: Due to imperfect analog processing, millimeter-wave communication is confronted with severe radio frequency impairments, such as in-phase/quadrature (IQ) imbalance. The presence of I/Q imbalance introduces image interference to the desired signal and can significantly degrade the performance if not compensated. In this paper, we propose a novel training-based compensation method for transmitter (TX) I/Q imbalance in millimeter-wave single carrier with frequency domain equalization (SC-FDE) systems. The novelty of the proposed method is that it can obtain the separate estimates of the TX I/Q imbalance and multipath channel. With the obtained estimates, we can easily conduct the FDE and compensate for the TX I/Q imbalance by simple operations. Simulations show that the proposed method can accurately estimate the TX I/Q imbalance and multipath channel and, thus, can achieve almost the same performance as the ideal case free of TX I/Q imbalance.

Frequency-Domain Detection without Matrix Inversions for mmWave Communications with Correlated Massive MIMO Channels

Abstract: Massive MIMO (m-MIMO) schemes operating at mmWave bands are being proposed to be used in next generation wireless systems, bringing new challenges both in terms of detection techniques and the definition of channel models. In this paper, frequency-domain iterative detection schemes which do not require matrix inversions and are suitable for m-MIMO systems employing Single- Carrier with Frequency-Domain Equalization (SC- FDE) modulations are considered. These techniques are evaluated using a general clustered channel model for multilayer m-MIMO systems. Performance results show that these techniques can approach the Matched Filter Bound (MFB) with just a few iterations, even with significant correlation between different antenna elements.

SC-FDE Based Full-Duplex Relay Communication Robust to Residual Loop Interference

Abstract: In this letter, we consider a full-duplex (FD) relay communication network on flat fading Rayleigh channels, where the relay is allowed to receive and transmit at the same time and over the same frequency band. Based on single carrier frequency domain equalization, we propose an amplify-and-forward protocol FD relaying scheme, which is robust to the residual loop interference. In this scheme, the relay only needs to amplify and forward the received signal by controlling the amplifying factor and as a result the processing at the relay is simple. The amplifying factor is optimized in terms of system parameters such as the length of cyclic prefix, noise power, and estimated channel state information. Simulation results are presented to evaluate the performance of the proposed scheme and verify the theoretical analysis.

Performance Evaluation of Low-Complexity FDE Receivers for Massive MIMO Schemes with 1-Bit ADCs

Abstract: Massive multiple input, multiple output (MIMO) schemes have been considered to support the physical layer of 5G systems and its combination with single-carrier with frequency-domain equalization (SC-FDE) schemes is particularly interesting for the uplink However, the receiver complexity increases with the number of antennas, and it is important to have low complexity massive MIMO schemes In this paper we consider the receiver design for the uplink of massive MIMO schemes where SC-FDE techniques are employed by the user terminals To achieve this, we empoly low resolution analog-to- digital converters (ADCs) at each receive branch of the BS, combined with low complexity FDE techniques It is shown that, although the nonlinear distortion levels inherent to the use of low resolution ADCs can be very high, we can have excellent performance, even with low complexity FDE receivers, provided that the number of receiver antennas is higher than the number of user terminals

Performance Analysis of OFDMA and SC-FDMA

Abstract: The main challenge in any high-speed digital communication system is how to maximize the data rate with minimizing the bit error rate. Several techniques have been developed to achieve this point. Some of these techniques are orthogonal frequency division multiplexing (OFDM), single-carrier frequency domain equalization (SC-FDE), orthogonal frequency division multiple access (OFDMA), and single-carrier frequency division multiple access (SC-FDMA). These four techniques are described briefly in this paper. Also, the paper measures the performances of OFDMA and SC-FDMA systems over international telecommunication union (ITU) vehicular-A channel using minimum mean square error (MMSE) equalization. Simulation results show that the performances with interleaved mapping outperform that with localized mapping. Also, the performances with quadrature phase shift keying(QPSK) are better than that with 16-ary quadrature amplitude modulation (16QAM). In addition, the performance of SC-FDMA is better than that of OFDMA, when QPSK is used, but the latter is little bit better than that of SC-FDMA when 16QAM is used

Nonlinear Effects of Radio over Fiber Transmission in Base Station Cooperation Systems

Abstract: In this paper we consider the uplink of Base Station (BS cooperation) systems, where each Mobile Terminal (MT) employs a Single-Carrier with Frequency-Domain Equalization (SC-FDE) modulation scheme The combined signals at each BS are detected and/or separated by a Central Processing Unit (CPU) with Iterative Block Decision Feedback Equalization (IB-DFE) receivers We consider a Radio-over-Fiber (RoF) link between the BS and the CPU, the electrical and optical conversions are performed by a Mach-Zehnder (MZ) modulator, which introduces nonlinear distortion We design robust receivers that take advantage of the statistical characteristics of the nonlinear distortion

A Simplified Massive MIMO Approach Using Precoding

Abstract: This paper considers the use of massive multiple input, multiple output (MIMO) combined with single-carrier with frequency-domain equalization (SC-FDE) modulations using a precoding approach. Although millimeter wave (mm-Wave) communications are expected to be a key part of 5G, these frequencies present considerable challenges due to high propagation free-space path losses and implementation difficulties. For this reason, it is desirable to have broadband mm-Wave communications with good power and spectral efficiencies that are compatible with high efficiency amplification. In this paper we propose a massive MIMO (m-MIMO) architecture for broadband mm-Wave communications using precoding approach. We consider three different types of precoding algorithms: Zero Forcing Transmitter (ZFT), Maximum Ratio Transmitter (MRT), and Equal Gain Combiner (EGT). The advantage of both MRT and EGT relies on avoiding the computation of pseudo-inverse of matrices. Their performance of MRT and EGT can be very close to the matched filter bound just after a few iterations of a new proposed interference cancellation, even when the number of receive antennas is not very high.

Novel Pilot Position Selection and Signal Reconstruction Methods for Frequency-Domain Pilot Multiplexing Techniques of SC-FDE

Abstract: The frequency-domain pilot multiplexing technique (FDPMT) has recently emerged as an appealing technique for channel estimation in single-carrier frequency-domain equalization (SC-FDE) systems due to the high spectral efficiency it promises. However, the performance of the FDPMT system is significantly affected by the signal distortion level, which depends on the pilot position selection (PPS) strategy at the transmitter and the signal reconstruction (SR) ability of the receiver. In this paper, the relationship between the interference pattern and the loss of equally spaced tones is discovered. By exploiting this relationship, we propose a novel PPS method and a novel SR method. The proposed PPS method, which is based on the minimization of the most severe intersymbol interference (ISI) experienced by those subblocks decimated from the transmitted signal block, dispenses with a priori knowledge of the channel statistics and imposes very low computational cost to the transmitter. The proposed SR method, which is based on the maximum-likelihood criterion, can be carried out subblock by subblock in parallel and sample by sample within each subblock, saving the computational complexity and time consumption of the receiver. Simulation results in terms of bit error rate (BER) corroborate the superiority of both proposed methods over their existing counterparts in various channels of interest.

Single Carrier Frequency Domain Equalization with Space-Time Trellis Codes

Abstract: Orthogonal Frequency Division Multiplexing (OFDM) is readily employed in wireless communication to combat the intersymbol interference (ISI) effect with limited success because as the capacity of MIMO systems increases, other destructive effects affect the propagation channels and/or overall system performance. As such, research interest has increased, on how to improve performance in the mediums where fading and ISI permeate, working on several combinatorial techniques to achieving improved effective throughput. In this study, we propose a combined model of the Space-Time Trellis Code (STTC) and Single-Carrier Frequency Domain Equalization (SC-FDE) to mitigate multiple-fading and interference effects. We present analytical performance results for the combined model over spatially correlated Rayleigh fading channels. We also show that it is beneficial to combine coding with equalization at the system’s receiving-end ensuring overall performance: a better performance over the traditional space-time trellis codes.

Frequency-Domain Receiver Design for Doubly Selective Channels

Abstract: This work is devoted to the broadband wireless transmission techniques, which are serious candidates to be implemented in future broadband wireless and cellular systems, aiming at providing high and reliable data transmission and concomitantly high mobility. In order to cope with doubly-selective channels, receiver structures based on OFDM and SC-FDE block transmission techniques, are proposed, which allow cost-effective implementations, using FFT-based signal processing. The first subject to be addressed is the impact of the number of multipath components, and the diversity order, on the asymptotic performance of OFDM and SC-FDE, in uncoded and for different channel coding schemes. The obtained results show that the number of relevant separable multipath components is a key element that influences the performance of OFDM and SC-FDE schemes. Then, the improved estimation and detection performance of OFDM-based broadcasting systems, is introduced employing SFN (Single Frequency Network) operation. An initial coarse channel is obtained with resort to low-power training sequences estimation, and an iterative receiver with joint detection and channel estimation is presented. The achieved results have shown very good performance, close to that with perfect channel estimation. The next topic is related to SFN systems, devoting special attention to time-distortion effects inherent to these networks. Typically, the SFN broadcast wireless systems employ OFDM schemes to cope with severely time-dispersive channels. However, frequency errors, due to CFO, compromises the orthogonality between subcarriers. As an alternative approach, the possibility of using SC-FDE schemes (characterized by reduced envelope fluctuations and higher robustness to carrier frequency errors) is evaluated, and a technique, employing joint CFO estimation and compensation over the severe time-distortion effects, is proposed. Finally, broadband mobile wireless systems, in which the relative motion between the transmitter and receiver induces Doppler shift which is different or each propagation path, is considered, depending on the angle of incidence of that path in relation to the ix

Efficient frequency-domain detection for massive MIMO systems

Abstract: Reduced-complexity implementations are critical for massive MIMO (Multiple Input, Multiple Output) systems. In this paper we consider the uplink of broadband massive MIMO systems employing SC-FDE (Single-Carrier with Frequency-Domain Equalization) schemes, where multiple users transmit to a single base station with a large number of antennas. We propose low-complexity frequency-domain detection schemes that allow excellent performance, but do not require matrix inversions.

On the performance of a widely linear SC-FDE system under multiple independent interferences

Abstract: In this paper, a new widely linear equalizer for single carrier systems using frequency domain equalization (SC-FDE) that takes into account up to K known interferers in the symbol estimation process is proposed It was found out that the error performance of the proposed widely linear equalizer is nearly immune to the effect of one interferer, regardless of its power; when compared to its strictly linear version, the proposed structure also has a better error performance for up to three interferers

Analytical BER Performance Evaluation in SISO and MIMO Environments with SC-FDE Modulations and IB-DFE Receivers

Abstract: This paper presents the analysis of the obtainment of the theoretical bit error rate (BER) performance in single-input–single-output and multiple-input–multiple-output systems with single-carrier with frequency-domain equalization modulations and iterative receivers based on the iterative block decision feedback equalization concept. Through the consideration of a Gaussian-based approach to obtain the BER performance, we present a simple and accurate model to improve such method by compensating the difference between the theoretical performance results and the ones obtained by simulation.

Robust Optimization of SC-FDE-Based Multihop DF Relay Systems With Imperfect CSI

Abstract: In this paper, we consider the robust transceiver optimization for a single-carrier frequency-domain equalization (SC-FDE)-based multihop half-duplex decode-and-forward (DF) relay system under imperfect channel state information (CSI). The goal is to maximize the system achievable bit rate (ABR) and to minimize the end-to-end bit error rate (BER) subject to a joint node power constraint. Due to the lack of analytical tractable expressions for ABR and BER under imperfect CSI, we resort to lower bounds of the hopwise ABRs and BERs and reformulate the original problem by using two approximated objective functions based on these lower bounds. For the reformulated problems, we show that the optimal equalization filters take the form of robust Wiener filters. Subsequently, we propose two efficient decentralized algorithms to obtain the optimal solutions for the resulting power-allocation problems. Numerical results are provided to confirm the ABR and BER performance of the proposed robust relaying schemes.

Iterative Decision Feedback Equalization for SC-FDE Systems Without Fine Timing Synchronization

Abstract: This letter deals with frequency domain equalization (FDE) in the presence of residual timing offsets. A novel iterative decision feedback equalizer for single-carrier FDE systems is proposed. Different from conventional schemes based on explicit point time-delay estimates, the proposed scheme operates directly on the oversampled matched filter output. For each iteration, FDE is performed first, and based on which, joint posterior distribution of the channel and timing parameters is obtained. A set of weights obtained from the corresponding posterior distribution, rather than explicit point time-delay estimate, are utilized for the time-delay compensation, eliminating the need of fine timing synchronization. Simulation results show that the proposed scheme enables evident performance improvement in terms of symbol error rate compared with conventional schemes under relative low sampling rate.

Self-correction phase noise compensation based on decision feedback in SC-FDE satellite systems

Abstract: Single-carrier frequency-domain equalization (SC-FDE) occupies a concise transmitting structure and a low peak-to-average power ratio (PAPR). These advantages are conducive to the miniaturization of the satellite systems and increase the robustness to the non-linear distortion of amplifiers. Nowadays, satellite communication systems set out to work at Ka or higher frequency bands to support the high data rate links. With the continuously rising level of the frequency in satellite communications, the effect of phase noise (PHN) also keeps increasing. So it is important to estimate and compensate the PHN in the SC-FDE satellite systems. In this paper, we design a novel self-correction phase noise compensation (SC-PNC) algorithm which is based on decision feedback in SC-FDE satellite systems. In the initial stage of our algorithm, with the aid of the receiver, the rough estimation of PHN is calculated by using the pilot signal, then the pilot rough compensation (PRC) is implemented. In the following self-correction stage, the feedback PHN is computed by the received and feedback signals. The inappropriate values are replaced according to the proposed self-correction threshold afterwards. Finally, the revised PHN compensates the received signal and we execute the front processes iteratively. The DVB-S2 and Wiener PHN models are considered in this paper. Experimental results show that the proposed algorithm can effectively improve the bit error rate (BER) performance.

Sparse channel estimation based on BP-MF improved algorithm in SC-FDE system

Abstract: A low complexity sparse Bayesian channel estimation algorithm has been proposed for SC-FDE receiver. The algorithm of combined belief propagation with mean field (BP-MF) applied into the Bayesian Hierarchical prior Model is obtained at first, and then use the algorithm of an generalized approximate message passing (GAMP) by approximating the algorithm of BP. Then the channel estimated values that are obtained in first iteration are sorted from big to small, and these small values are deleted to further reduce the complexity of computational. Finally, the MF method is applied to the Frequency Domain Equalization. The experiment results demonstrate that the proposed method has nearly the same performance compared to the MF algorithm in estimation precision of the channel and Bit Error Rate (BER), and it also has much less computational complexity.

Sparse Channel Estimation Based on Improved BP-MF Algorithm in SC-FDE System

Abstract: A low complexity sparse Bayesian channel estimation algorithm was proposed for SC-FDE receiver The proposed algorithm firstly applies the combined belief propagation and mean field (BP-MF) algorithm to the Bayesian Hierarchical Prior Model and obtained by approximating some BP messages using generalized approximate message passing (GAMP) algorithm Then we put the channel estimated values that are acquired from the first iteration in such an order-from big to small and further reduce the computational complexity, we eliminate some small value to achieve this goal Finally, we applied the MF method to the Frequency Domain Equalization Numerical results demonstrate that the proposed method has nearly the same performance as compared to the MF algorithm in estimation precision of the channel and Bit Error Rate (BER) while it has much less computational complexity as compared to the MF algorithm

Robust design of SC-FDE based two-way relay systems under channel uncertainty

Abstract: In this paper, we consider the robust transceiver design for a single-carrier frequency-domain equalization (SC-FDE) based two-way amplify-and-forward (AF) relay system with imperfect channel state information (CSI). We formulate the optimization problem for the relay filter and destination equalizers as the maximization of the achievable bit rate (ABR) of the system subject to a relay transmit power constraint. Due to the lack of analytical tractable expression for the system ABR under imperfect CSI, solving the optimization problem directly is challenging. Thereby, a lower bound on the link ABR is first derived and adopted in the objective function. Based on the lower bound, the optimal equalizers at the two terminal nodes can be determined in closed form. Subsequently, the optimization of the relay filter is transformed into a convex power allocation problem and an efficient algorithm is proposed to find its global optimal solution. Numerical results are provided to confirm the ABR performance of the proposed robust two-way AF relaying strategy.