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Showing papers on "SC-FDE published in 2013"


Journal ArticleDOI
TL;DR: A novel relay selection strategy, selective-to-flat fading relay selection (SFRS), in which from the effective frequency selective source-relay-destination channel link associated with the selected relay, only the channel tab with highest power is passed to the destination terminal.
Abstract: In this paper, we investigate several relay selection strategies for cooperative Single-Carrier Frequency-Domain Equalization (SC-FDE) with the amplify-and-forward protocol. We consider both maximum likelihood (ML)-SC-FDE and minimum mean square error (MMSE)-SC-FDE receivers. We provide a novel pairwise error probability (PEP)-based selection criterion (SHARM) for frequency selective channels. We further present several selection strategies for cooperative (C) MMSE-SC-FDE receivers, which are motivated by minimizing the instantaneous error rate. These are, norm-based relay selection (NBRS), instantaneous mutual information-based relay selection (CBRS), singular value based relay selection (SVRS), and equalizer output signal quality-based relay selection (EQRS) strategies. We further propose a novel relay selection strategy, selective-to-flat fading relay selection (SFRS), in which from the effective frequency selective source-relay-destination channel link associated with the selected relay, only the channel tab with highest power is passed to the destination terminal. Additionally, to tackle the multiple relay selection problem considering generic mobile scenarios with moderately fast fading channels, in order to select the near best relay subset within the minimum processing time, we apply estimation of distribution algorithm (EDA) and formulate a modified EDA for the relay selection problem. Our results show promising performance of EDA with comparable computational complexity.

27 citations


Journal ArticleDOI
TL;DR: The results show that the use of chaotic interleaving with CPM-OFDM andCPM-SC-FDE systems provides a good trade-off between system performance and bandwidth efficiency.
Abstract: In this paper, we present a chaotic interleaving scheme for both the Continuous Phase Modulation (CPM) based Orthogonal Frequency Division Multiplexing (CPM-OFDM) and CPM-based Single-Carrier Frequency-Domain Equalization (CPM-SC-FDE) systems. Chaotic interleaving is used to generate permuted versions from the sample sequences to be transmitted with low correlation among their samples, and hence a better Bit Error Rate (BER) performance can be achieved. The proposed CPM-OFDM and CPM-SC-FDE systems with chaotic interleaving combine the advantages of the frequency diversity and the high power efficiency of the CPM-based systems and the performance improvements due to chaotic interleaving. The BER performance of the both systems with and without chaotic interleaving is evaluated by computer simulations. Also, a comparison between chaotic interleaving and block interleaving is performed. Simulation results show that, the proposed chaotic interleaving scheme can greatly improve the performance of the CPM-OFDM system and the CPM-SC-FDE system. Furthermore, the results show that the chaotic interleaving scheme outperforms the traditional block interleaving scheme in both systems. The results also show that the use of chaotic interleaving with CPM-OFDM and CPM-SC-FDE systems provides a good trade-off between system performance and bandwidth efficiency.

18 citations


Proceedings ArticleDOI
01 Nov 2013
TL;DR: In this article, the authors proposed a burst single-carrier frequency domain equalization (SC-FDE) for data transmission, which co-exists with radar equipments in time-division multiplexing mode.
Abstract: Recently the radar-based communication has aroused a great interest in the military and academia due to its great potential in increasing performance and reducing costs. However, the application of high-speed data transmission over radar antennas requires a burst waveform robust to nonlinear power amplifiers and multipath propagation effects. Our solution is to apply burst single-carrier frequency domain equalization (SC-FDE) for data transmission, which co-exists with radar equipments in time-division multiplexing mode. In this paper, we present a system that contains a training preamble and lots of data blocks. Based on the training preamble, a joint algorithm is proposed for fast synchronization. Moreover, signals are phase-modulated to combat the effects of nonlinear analog circuits and unique words are inserted between data blocks as guard intervals to eliminate inter block interference. The proposed scheme is evaluated by both simulations and field experimental demonstrations, where bit error rate

12 citations


Proceedings ArticleDOI
Changming Zhang1, Zhenyu Xiao1, Bo Gao1, Li Su1, Depeng Jin1 
09 Jun 2013
TL;DR: Comprehensive simulations indicate that the proposed architecture employing the proposed ITR-PNC achieves competitive bit-error-rate (BER) performance with only two iterations, for the cases whether only RPN or both TPN and RPN are taken into consideration.
Abstract: Due to the extremely high oscillation frequency of 60 GHz systems, phase noise (PN) imported at both transmitter (Tx) and receiver (Rx) is significant, which degrades the transmission performance. This paper proposes an architecture employing iterative Tx and Rx PN compensation (ITR-PNC) for 60 GHz systems with single-carrier frequency-domain equalization (SC-FDE) transmission. The ITR-PNC iteratively performs PNC before equalization (PNC-BE) and PNC after equalization (PNC-AE), which are mainly set to manage Rx PN (RPN) and Tx PN (TPN), respectively. The PNC-BE and PNC-AE both exploit the one-tap least mean square (LMS) algorithm for PN extraction (PNE). In PNC-AE, the decision feedback result is used as the reference signal for PNE. And in PNC-BE, the reference signal is the signal replica, which is generated via the decision result and the estimated TPN of last iteration, and the estimated channel response. Comprehensive simulations indicate that the proposed architecture employing the proposed ITR-PNC achieves competitive bit-error-rate (BER) performance with only two iterations, for the cases whether only RPN or both TPN and RPN are taken into consideration.

11 citations


Patent
26 Jun 2013
TL;DR: In this article, a phase noise suppression method under the low-complexity channel estimation of an SC-FDE (single carrier-frequency domain equalization) system was proposed, which comprises the following steps of: forming a training sequence by virtue of special characters, obtaining the responses of a small amount of frequency points of CFR (crest factor reduction) and a CIR (channel impulse response) according to the received signal.
Abstract: The invention discloses a phase noise suppression method under the low-complexity channel estimation of an SC-FDE (single carrier-frequency domain equalization) system The phase noise suppression method comprises the following steps of: forming a training sequence by virtue of special characters, obtaining the responses of a small amount of frequency points of CFR (crest factor reduction) and a CIR (channel impulse response) by virtue of a LS (least square) algorithm according to the received signal, obtaining the initial CFR influenced by a phase noise CPE (common phase error) via a discrete Fourier transform interpolation filter, and performing time-domain noise power estimation and frequency-domain noise power estimation according to the training sequence; after an established channel is obtained, extracting the effective order of the CIR in a time domain, and calculating the copy of the special character received signal; using special characters as cyclic prefixes of transmission data blocks, estimating the ratio of the CPE on one cyclic prefix to the CPE in the initial established channel by virtue of an MMSE (minimum mean square error) algorithm, and then obtaining the ratio of the CPE of the whole data block to the CPE in the initial established channel via linear interpolation; and finally multiplying the CPE ratio with the initial CIR influenced by the phase noise CPE to track the whole channel of the present data block, and suppressing phase noise interference via the frequency-domain MMSE equalization The channel estimation algorithm disclosed by the invention is low in complexity, thus reducing the complexity of a phase noise suppression algorithm

7 citations


Journal ArticleDOI
TL;DR: In this article, a joint transceiver design for single-carrier frequency-domain equalization (SC-FDE) based multiple-input multiple-output (MIMO) relay systems is proposed.
Abstract: In this paper, we propose a joint transceiver design for single-carrier frequency-domain equalization (SC-FDE) based multiple-input multiple-output (MIMO) relay systems. To this end, we first derive the optimal minimum mean-squared error linear and decision-feedback frequency-domain equalization filters at the destination along with the corresponding error covariance matrices at the output of the equalizer. Subsequently, we formulate the source and relay precoding matrix design problem as the minimization of a family of Schur-convex and Schur-concave functions of the mean-squared errors at the output of the equalizer under separate power constraints for the source and the relay. By exploiting properties of the error covariance matrix and results from majorization theory, we derive the optimal structures of the source and relay precoding matrices, which allows us to transform the matrix optimization problem into a scalar power optimization problem. Adopting a high signal-to-noise ratio approximation for the objective function, we obtain the global optimal solution for the power allocation variables. We illustrate the excellent performance of the proposed system and compare it to that of conventional orthogonal frequency-division multiplexing MIMO relay systems based on computer simulations.

7 citations


Proceedings ArticleDOI
01 Nov 2013
TL;DR: This paper considers SC-FDE schemes (Single-Carrier with Frequency-Domain Equalization) combined with multilevel constellations that can be decomposed as the sum of BPSK (Binary Shift Keying) signals, which allows the definition of new efficient IB-DFE (Iterative Block Decision Feedback Feedback Equalization), with low impact on system complexity.
Abstract: Multilevel modulations have good spectral efficiency, although at the expense of power efficiency. In mobile wireless systems, where there are strict power and bandwidth constrains, we must maximize the power efficiency. This means the use of high-efficiency amplification schemes at the transmitter side and compact constellations combined with powerful equalizers at the receiver side. In this paper we consider SC-FDE schemes (Single-Carrier with Frequency-Domain Equalization) combined with multilevel constellations that can be decomposed as the sum of BPSK (Binary Shift Keying) signals. These components can be separately amplified and besides this decomposition allows the definition of new efficient IB-DFE (Iterative Block Decision Feedback Equalization) implementations suitable for multilevel constellations, with low impact on system complexity.

6 citations


Patent
08 May 2013
TL;DR: In this article, an integer frequency doubling offset and channel parameter joint estimation algorithm with an ultra-low complexity in a single carrier frequency domain equalization (SC-FDE) system is presented.
Abstract: The invention discloses an integer frequency doubling offset and channel parameter joint estimation algorithm with an ultra-low complexity in a single carrier frequency domain equalization (SC-FDE) system. The algorithm comprises the following steps: (1) generating a training sequence; (2) obtaining a frequency domain signal of a receiving end; (3) constructing a mutual fuzzy function Doppler zero section of a Chu sequence; (4) constructing a metric function: utilizing the zero section of the Chu sequence to conduct joint estimation for an integer frequency doubling offset and channel parameter, and constructing the metric function; (5) obtaining integer frequency doubling offset estimation from the metric function; (6) obtaining corresponding time domain channel swashing response estimation according to the integer frequency doubling offset estimation. Characters of a mutual fuzzy function of the Chu sequence are utilized by the algorithm, the algorithm just needs using the zero section to construct an estimation metric function, and the algorithm not only can conduct estimation for integer frequency doubling offset, but also simultaneously can conduct channel estimation. Compared with a traditional algorithm, the algorithm which does not need multi-group cross-correlation operation has the ultra-low complexity.

5 citations


Proceedings ArticleDOI
02 Jun 2013
TL;DR: A subspace decomposition approach for semi-blind channel estimation in SC-FDE systems is proposed as a means to reduce or eliminate the need for pilot symbols and increase their overall spectral efficiency.
Abstract: Single carrier frequency division multiple access (SC-FDMA), a multiple user access scheme based on the single carrier frequency domain equalization (SC-FDE) technique, has been proposed for the uplink in fourth generation (4G) mobile communications. SC- FDE requires reliable channel estimates to maintain an acceptable bit error rate (BER) performance. Much research focuses on the use of pilot symbols which reduces the spectral efficiency of SC-FDE systems. In this paper, we propose a subspace decomposition approach for semi-blind channel estimation in SC-FDE systems as a means to reduce or eliminate the need for pilot symbols and increase their overall spectral efficiency. Simulation results show that, under the conditions presented in this paper, a BER of 10-3 can be achieved with a power loss of roughly 1 dB compared to a system with perfect channel estimates. This result is achieved with channel estimates that have a normalized mean square error (NMSE) less than 1%.

5 citations


Proceedings ArticleDOI
09 Jun 2013
TL;DR: An interference cancellation receiver that exploits the unique characteristics of single-carrier frequency-division multiple access based systems is proposed and results indicate that proposed methods work particularly well for low overlap ratios compared to interference coordination and no cancellation methods.
Abstract: Interference cancellation is expected to have significant importance for next-generation wireless communication systems due to various co-channel deployment scenarios and dense frequency reuse. In this study, an interference cancellation receiver that exploits the unique characteristics of single-carrier frequency-division multiple access based systems is proposed. The proposed receiver suppresses the co-channel dominant interference by employing a soft window to the frequency-domain samples where the desired and interfering signals overlap. In order to improve the performance, demodulation and regeneration stages are repeated multiple times by initially accommodating a group of reliable symbols before the iterations. The simulation results indicate that proposed methods work particularly well for low overlap ratios compared to interference coordination and no cancellation methods.

4 citations


Journal ArticleDOI
TL;DR: The optimal structure of the Tx-BF matrix is obtained in closed form and an efficient algorithm is proposed for computing the optimal power allocation and results validate the excellent performance of the proposed scheme in terms of uncoded bit-error rate and achievable bit rate.
Abstract: Transmit beamforming (Tx-BF) for multiple-input multiple-output (MIMO) channels is an effective means to improve system performance. In frequency-selective channels, Tx-BF can be implemented in combination with single-carrier frequency-domain equalization (SC-FDE) to combat inter-symbol interference. In this paper, we consider the optimal design of the Tx-BF matrix for a MIMO SC-FDE system employing a linear minimum mean square error (MSE) receiver. We formulate the Tx-BF optimization problem as the minimization of a general function of the stream MSEs, subject to a transmit power constraint. The optimal structure of the Tx-BF matrix is obtained in closed form and an efficient algorithm is proposed for computing the optimal power allocation. Our simulation results validate the excellent performance of the proposed scheme in terms of uncoded bit-error rate and achievable bit rate.

Posted Content
TL;DR: In this paper, the optimal design of the Tx-BF matrix for a MIMO SC-FDE system employing a linear minimum mean square error (MSE) receiver is considered.
Abstract: Transmit beamforming (Tx-BF) for multiple-input multiple-output (MIMO) channels is an effective means to improve system performance. In frequency-selective channels, Tx-BF can be implemented in combination with single-carrier frequency-domain equalization (SC-FDE) to combat inter-symbol interference. In this paper, we consider the optimal design of the Tx-BF matrix for a MIMO SC-FDE system employing a linear minimum mean square error (MSE) receiver. We formulate the Tx-BF optimization problem as the minimization of a general function of the stream MSEs, subject to a transmit power constraint. The optimal structure of the Tx-BF matrix is obtained in closed form and an efficient algorithm is proposed for computing the optimal power allocation. Our simulation results validate the excellent performance of the proposed scheme in terms of uncoded bit-error rate and achievable bit rate.

Proceedings ArticleDOI
01 Oct 2013
TL;DR: The 8-parallel high-speed structure has been implemented on a Xilinx Virtex-6 FPGA device, where the maximum throughput of channel-estimation and equalization modules can be up to 1.76 Gbps and 1.44 Gbps, respectively.
Abstract: In this paper, we design high-throughput structures of channel estimation and equalization modules for 60 GHz SC-FDE transmission based on the IEEE 802.11ad standard. In the implementations of high speed transmission, inter-symbol interference (ISI) is significant, which severely degrades the biterror-rate (BER) performance. So channel estimation and equalization are particularly important in receiver. In the channel-estimation module, efficient Golay correlator (EGC) that has low complexity is exploited. Radix-22 fast-Fourier-transform (FFT) algorithm and pipeline-processing method are adopted in the equalization module. The divider used in the calculation of equalizer coefficient is designed with lookup table (LUT). At last, the 8-parallel high-speed structure has been implemented on a Xilinx Virtex-6 FPGA device, where the maximum throughput of channel-estimation and equalization modules can be up to 1.76 Gbps and 1.44 Gbps, respectively.

Proceedings ArticleDOI
Deliang Liu, Qiang Huang, Dazhuan Xu1, Tong Cui, Yongli Zhu 
01 Oct 2013
TL;DR: A joint algorithm of iterative equalization and iterative channel estimation is proposed that makes use of the iterative block feedback equalization (IB-DFE) to combat the serious effect of the channel's deep frequency-selective fading for the single-carrier frequency domain equalization.
Abstract: The channel estimation accuracy has great impact on the bit error ratio performance of the single-carrier broadband wireless communication system. In order to enhance the channel estimation accuracy when the length of pilot is limited, a joint algorithm of iterative equalization and iterative channel estimation is proposed. This algorithm makes use of the iterative block feedback equalization (IB-DFE) to combat the serious effect of the channel's deep frequency-selective fading for the single-carrier frequency domain equalization. And the soft-modulated signal feeding back from the channel decoder will be used to obtain more accurate channel estimation. Then these estimated values will be available in the next iteration of equalization to achieve better equalization performance. So the equalizer and the channel estimator will build good relationship of improving performance between each other. The simulation results show that the joint algorithm exhibits superior performance in conditions of different channel in contrast to the iterative equalization algorithm only obtaining channel estimation from pilot sequence.

Journal ArticleDOI
TL;DR: Simulation results show that the BER performance of the proposed scheme is better than QOSTBC for four transmit antennas, and isbetter than OSTBC (orthogonal space-time block code) in the low SNR regime.
Abstract: Conventional space-time block codes are normally designed and studied for Rayleigh flat fading channels. As Single Carrier Frequency-Domain Equalization (SC-FDE) can help to combat the Inter-Symbol Interference (ISI) caused by multipath radio channels, this paper investigates quasi- orthogonal space-time block code (QOSTBC) with Givens rotation in order to enhance the reliability of the SC-FDE transmission in the frequency selective fading channels. To use QOSTBC with Givens rotation for the SC-FDE system, the encoding is performed on the data block basis, and we derive the corresponding decoding method performing in the frequency domain at the receiver. With Givens rotation, the correlation of channel equivalent matrix is eliminated, and the decoding can be performed with linear combiner at the receiver. Such a proposed scheme can achieve full rate transmission and provide high diversity gain. Simulation results show that the BER performance of the proposed scheme is better than QOSTBC for four transmit antennas, and is better than OSTBC (orthogonal space-time block code) in the low SNR regime. 1

Proceedings ArticleDOI
25 Nov 2013
TL;DR: This paper investigates the use of subspace decomposition and derive a novel algorithm for the blind estimation of MU-MIMO channels in SC-FDE systems, as specified by the 3GPP LTE, and demonstrates the advantages of the proposed blind subspace-based channel estimation algorithm.
Abstract: Multiuser multiple-input multiple-output (MU-MIMO) wireless systems that employ single-carrier frequency-domain equalization (SC-FDE) for uplink transmissions can provide high data rates with increased spectral efficiency under severe channel conditions. However, the availability of accurate channel estimates at the base station (BS) receiver is crucial for achieving peak performance. In this paper, we investigate the use of subspace decomposition and derive a novel algorithm for the blind estimation of MU-MIMO channels in SC-FDE systems, as specified by the 3GPP LTE. By exploiting the long data blocks available in LTE standards, our proposed blind algorithm can obtain accurate estimates of the MU-MIMO channels over every block of transmitted data. This provides for a bandwidth-efficient solution in SC-FDE systems by eliminating (reducing) the need to allocate an entire block of pilot sequences for each active transmitter. Furthermore, since the channel estimation is deployed at the BS, the computational complexity is not considered to be a significant burden for future systems in exchange for the increased spectral efficiency. The results of simulations over fading channels, using realistic system parameters representative of LTE-Advanced, demonstrate the advantages of our proposed blind subspace-based channel estimation algorithm and support the feasibility of the resulting MU-MIMO SC-FDE scheme with reduced training.

Journal ArticleDOI
TL;DR: This study carries out theoretical analysis combined with computer simulations for performance comparisons between uncoded orthogonal frequency division multiplexing (OFDM) and single-carrier frequency-domain equalization (SC-FDE) systems on frequency- selective static channels as well as frequency-selective fading channels.
Abstract: In this study, we carry out theoretical analysis combined with computer simulations for performance comparisons between uncoded orthogonal frequency division multiplexing (OFDM) and single-carrier frequency-domain equalization (SC-FDE) systems on frequency-selective static channels as well as frequency-selective fading channels. We consider both zero-forcing and minimum mean square error equalizations for data detection. Theoretical evaluations for output signal-to-noise ratio and error rate performance are presented for both OFDM and SC-FDE systems. Then, error rate bounds for both systems are derived. Combining all the analytical results with computer simulations, we reach certain important conclusions on the superiority between OFDM and SC-FDE systems.

Proceedings ArticleDOI
25 Nov 2013
TL;DR: Under network total power constraint, this paper presents optimal relay beamforming for the multiuser two-way relay system, where the relay transceiver processor is designed based on the minimum mean-square-error (MMSE) criterion.
Abstract: In this paper, we investigate cooperative Single-Carrier Frequency-Domain Equalization (SC-FDE) for two-way relay networks, where multiple users each equipped with multiple antennas exchange their information through a multi-antenna relay node in a bi-directional manner. Under network total power constraint, we present optimal relay beamforming for the multiuser two-way relay system, where the relay transceiver processor is designed based on the minimum mean-square-error (MMSE) criterion. We drive a closed-form expression for the signal-to-interference noise ratio (SEVR) at each of the user terminals, and further present a joint user-relay antenna selection algorithm by applying the estimation of distribution algorithm (EDA). The proposed EDA has a low computational complexity, and its effectiveness is verified through simulation results.

Proceedings ArticleDOI
21 Sep 2013
TL;DR: A novel time-frequency domain two-dimensional MMSE channel estimation (2D-MMSE) algorithm based on separation property of mobile wireless channels is proposed in this paper to provide the current channel state knowledge and improve the spectral efficiency in Single Carrier Frequency Domain Equalization (SC-FDE) systems over frequency-selective channels.
Abstract: A novel time-frequency domain two-dimensional MMSE channel estimation (2D-MMSE) algorithm based on separation property of mobile wireless channels is proposed in this paper in order to provide the current channel state knowledge and improve the spectral efficiency in Single Carrier Frequency Domain Equalization (SC-FDE) systems over frequency-selective channels. We use the Unique Word (UW) to be the cyclic prefix and the pilot just like IEEE802.16. The UW is not need to delete in receiver, so the overhead of system is low. The 2D-MMSE estimation is simplified as an MMSE interpolation in the frequency domain cascaded by an MMSE filter in the time domain. The SVD method is adopt to reduce the complexity and keep the estimation accuracy. We also make the noise variance estimation by UW. Finally, the simulation results show that the proposed algorithm has better performance than the LS and MMSE algorithms, and the complexity of our method is lower than traditional one-dimensional MMSE.

Journal ArticleDOI
TL;DR: A p-persistent Network Diversity Multiple Access (NDMA) random MAC protocol designed to cope with a total number of mobile terminals J, for a maximum decoding capability of Qmax simultaneous packets is proposed and evaluated.
Abstract: This paper presents a Medium Access Control (MAC) protocol solution designed to properly handle collisions when in the presence of a multi-packet detection receiver for Single-Carrier (SC) modulations with Frequency-Domain Equalization (FDE). It is considered an iterative frequency-domain receiver that jointly performs equalization, multi-packet separation and channel decoding operations, for up to Qmax mobile terminals transmitting in one slot. In this work, it is proposed and evaluated a p-persistent Network Diversity Multiple Access (NDMA) random MAC protocol designed to cope with a total number of mobile terminals J, for a maximum decoding capability of Qmax simultaneous packets. An accurate analytical model is presented to optimize two different scenarios: in the first one, a saturated network is considered and it is determined the packet transmission probability that maximizes the uplink throughput; the second represents a non-saturated network and the goal is to compute the optimal transmission probability associated to each mobile terminal that minimizes the packet transmission delay. In the end, analytical results obtained through physical and MAC layer simulations are discussed.

Journal ArticleDOI
TL;DR: A modified single-carrier frequency domain domain equalization scheme implemented in directly detected wavelength-division-multiplexed passive optical networks (WDM-PONs) is proposed and it is observed that the time-clipping scheme can bring roughly 1-dB power penalty improvement over conventional equalization schemes.
Abstract: We propose a modified single-carrier frequency domain equalization (SC-FDE) scheme implemented in directly detected wavelength-division-multiplexed passive optical networks (WDM-PONs). A time-clipping technique is used in FDE to perform noise filtering. In the simulation, where the channel is modeled with chromatic dispersion and direct detection, performance improvement is achieved by exploring the clipping position and retained gradient vector length. In the experiment, we investigate the time-clipping SC-FDE implemented in 10-Gb/s direct-detected WDM-PON using an uncooled free-running 1550-nm vertical cavity surface emitting laser. After 30-km transmission, it is observed that the time-clipping scheme can bring roughly 1-dB power penalty improvement over conventional equalization schemes.

Posted Content
TL;DR: Two adaptive detection schemes based on single-carrier frequency domain equalization for multiuser direct-sequence ultra-wideband (DS-UWB) systems are proposed, which are termed structured channel estimation (SCE) and direct adaptation (DA).
Abstract: In this paper, we propose two adaptive detection schemes based on single-carrier frequency domain equalization (SC-FDE) for multiuser direct-sequence ultra-wideband (DS-UWB) systems, which are termed structured channel estimation (SCE) and direct adaptation (DA). Both schemes use the minimum mean square error (MMSE) linear detection strategy and employ a cyclic prefix. In the SCE scheme, we perform the adaptive channel estimation in the frequency domain and implement the despreading in the time domain after the FDE. In this scheme, the MMSE detection requires the knowledge of the number of users and the noise variance. For this purpose, we propose simple algorithms for estimating these parameters. In the DA scheme, the interference suppression task is fulfilled with only one adaptive filter in the frequency domain and a new signal expression is adopted to simplify the design of such a filter. Least-mean squares (LMS), recursive least squares (RLS) and conjugate gradient (CG) adaptive algorithms are then developed for both schemes. A complexity analysis compares the computational complexity of the proposed algorithms and schemes, and simulation results for the downlink illustrate their performance.

Patent
18 Jul 2013
TL;DR: In this paper, a signal processing method based on single carrier-frequency domain equalization (SC-FDE) is proposed, which includes an optical transmitter generating unique words (UW) sequence and a synchronous data block, providing a data frame with the unique words sequence, and transmitting the superframe as a baseband signal to an optical receiver.
Abstract: A signal processing method based on single carrier-frequency domain equalization(SC-FDE), includes: an optical transmitter generating unique words(UW) sequence and a synchronous data block, providing a data frame with the unique words sequence, generating a superframe by the synchronous data block and the data frame, and transmitting the superframe as a base-band signal to an optical receiver A signal processing system is based on SC-FDE Said solution enable simplifying a process of an optical transmitter hardware device, reducing manufacturing cost of the optical transmitter, improving accuracy of time synchronization and reducing processing resources of channel estimation

Patent
06 Mar 2013
TL;DR: In this paper, an adaptive modulation and coding method based on an SC-FDE (Single Carrier-Frequency Domain Equalization) system, relates to an AMC modulation and encoding method, and belongs to the field of wireless radio.
Abstract: The invention provides an AMC (Adaptive Modulation and Coding) method based on an SC-FDE (Single Carrier-Frequency Domain Equalization) system, relates to an AMC modulation and encoding method, and belongs to the field of wireless radio. In order to solve the problems that the a channel cost is increased and the spectrum efficiency is low under the condition that the SC-FDE system is at a time-varying multi-path channel, caused by that a channel needs to be subjected to estimation and policy exchange at any time when current information is transmitted, the invention provides the adaptive modulation and coding method by combining an AMC technology and self characteristics of an SC-FDE system theory; policy lasting time is introduced to restrict the utilization time of the policy and the switching frequency of the policy, so that the optimal policy which is matched with the current channel state is searched in a policy switching table; only if the average lasting time of the selected optimal policy is exceeded, the method can carry out the next time of the selection and the switching of the optimal transmission policy, so that the channel estimation and policy switching processing efficiencies are reasonably reduced, the spectrum efficiency is effectively improved and the system throughput is maximized. The AMC method based on the SC-FDE system is applicable to the field of a wireless radio communication technology.

Proceedings ArticleDOI
Xuefei Liao1, Yong Bai1
01 Nov 2013
TL;DR: Two symbol timing synchronization algorithms based on a novel structure of training symbol that can take advantage of the correlations of the four parts of the training symbol to efficiently improve the accuracy of timing synchronization and the anti-multipath capability are proposed.
Abstract: Symbol timing synchronization is a key technology for SC-FDE (Single Carrier Frequency Domain Equalization) systems. The traditional Schmidl & Cox's and Minn's algorithms have some shortcoming on the existence of timing metric plateau and redundant peaks. To overcome these shortcomings, two symbol timing synchronization algorithms based on a novel structure of training symbol are proposed for SC-FDE systems in this paper. The proposed methods can take advantage of the correlations of the four parts of the training symbol to efficiently improve the accuracy of timing synchronization and the anti-multipath capability. The simulation results confirm that the performances of the proposed algorithms are superior to Minn's algorithm in AWGN channel and 3GPP Vehicular A channel.

Proceedings ArticleDOI
25 Jul 2013
TL;DR: The paper shows the principle of SC-FDE and proposes a synchronization scheme applied in HF communication based on the analysis of timing synchronization and frequency offest compensation method and shows the simulation result of the system performance under the MATLAB tool.
Abstract: Synchronization technology is another key technology except for the equalization in SC-FDE,and it influences the performance of the communication system in a certain degree. The paper shows the principle of SC-FDE and propose a synchronization scheme applied in HF communication based on the analysis of timing synchronization and frequency offest compensation method. At last shows the simulation result of the system performance under the MATLAB tool.

Patent
22 Mar 2013
TL;DR: In this paper, a phase noise suppression method under the low-complexity channel estimation of an SC-FDE (single carrier-frequency domain equalization) system was proposed, which comprises the following steps of: forming a training sequence by virtue of special characters, obtaining the responses of a small amount of frequency points of CFR (crest factor reduction) and a CIR (channel impulse response) according to the received signal.
Abstract: The invention discloses a phase noise suppression method under the low-complexity channel estimation of an SC-FDE (single carrier-frequency domain equalization) system. The phase noise suppression method comprises the following steps of: forming a training sequence by virtue of special characters, obtaining the responses of a small amount of frequency points of CFR (crest factor reduction) and a CIR (channel impulse response) by virtue of a LS (least square) algorithm according to the received signal, obtaining the initial CFR influenced by a phase noise CPE (common phase error) via a discrete Fourier transform interpolation filter, and performing time-domain noise power estimation and frequency-domain noise power estimation according to the training sequence; after an established channel is obtained, extracting the effective order of the CIR in a time domain, and calculating the copy of the special character received signal; using special characters as cyclic prefixes of transmission data blocks, estimating the ratio of the CPE on one cyclic prefix to the CPE in the initial established channel by virtue of an MMSE (minimum mean square error) algorithm, and then obtaining the ratio of the CPE of the whole data block to the CPE in the initial established channel via linear interpolation; and finally multiplying the CPE ratio with the initial CIR influenced by the phase noise CPE to track the whole channel of the present data block, and suppressing phase noise interference via the frequency-domain MMSE equalization. The channel estimation algorithm disclosed by the invention is low in complexity, thus reducing the complexity of a phase noise suppression algorithm.

Proceedings ArticleDOI
02 Jun 2013
TL;DR: A low complexity linear FDE is proposed which incorporates knowledge of the channel estimation error variance and derive analytical BER expressions and it is shown that its performance becomes more robust in the presence of strongChannel estimation error components compared with a conventional FDE receiver.
Abstract: Imperfect channel estimation can have a severe impact on the performance of coherent detection systems. In this paper we study the effect of imperfect channel knowledge in the performance of SC-FDE (Single Carrier with Frequency Domain Equalization). We propose a low complexity linear FDE which incorporates knowledge of the channel estimation error variance and derive analytical BER expressions. It is shown that its performance becomes more robust in the presence of strong channel estimation error components compared with a conventional FDE receiver. We also compare the degradation caused by imperfect channel estimation in SC-FDE and in OFDM schemes (Orthogonal Frequency Division Multiplexing) and show that the channel estimation requirements for SC-FDE are higher than for OFDM.

Proceedings ArticleDOI
01 Jan 2013
TL;DR: This paper considers the use of Single Carrier Frequency-Domain Equalization (SC-FDE) scheme in Single Frequency Network (SFN) broadcasting systems and proposes a set of receiver structures which are able to compensate the variations of the equivalent channel.
Abstract: In this paper we consider the use of Single Carrier Frequency-Domain Equalization (SC-FDE) scheme in Single Frequency Network (SFN) broadcasting systems, with the objective of studying the impact of distinct Carrier Frequency Offset (CFO) between the local oscillator at each transmitter and the local oscillator at the receiver. We consider a specific scenario in order to propose an efficient method for estimating the channel frequency response and CFO associated to each transmitter. We also propose a set of receiver structures which are able to compensate the variations of the equivalent channel. The performance results show that we can have excellent performance, even when the considered transmissions have substantially different CFOs.

Proceedings ArticleDOI
01 Nov 2013
TL;DR: A high-accuracy closed-loop frequency offset tracking algorithm based on the differential correlation between the pilot sequences in two adjacent frames is proposed and by means of unique word (UW) sequence the robust timing tracking is implemented in early-late phase-locked loop.
Abstract: The performance of the broadband wireless communication system with single carrier frequency domain equalization (SC-FDE) will be affected seriously by the tracking accuracy of frequency offset and timing offset. Especially when the length of the frame is high the frequency tracking must be very accurate. But in multi-path fading channel if the general frequency tracking loop is used the stable tracking error will occur. In order to solve this problem a high-accuracy closed-loop frequency offset tracking algorithm based on the differential correlation between the pilot sequences in two adjacent frames is proposed. And by means of unique word (UW) sequence the robust timing tracking is implemented in early-late phase-locked loop. The simulation results show that the frequency tracking and timing tracking algorithm given by this paper has good tracking performance even when SNR is very low.