Frequency domain equalization for single-carrier broadband wireless systems
TL;DR: This article surveys frequency domain equalization (FDE) applied to single-carrier (SC) modulation solutions and discusses similarities and differences of SC and OFDM systems and coexistence possibilities, and presents examples of SC-FDE performance capabilities.
Abstract: Broadband wireless access systems deployed in residential and business environments are likely to face hostile radio propagation environments, with multipath delay spread extending over tens or hundreds of bit intervals. Orthogonal frequency-division multiplex (OFDM) is a recognized multicarrier solution to combat the effects of such multipath conditions. This article surveys frequency domain equalization (FDE) applied to single-carrier (SC) modulation solutions. SC radio modems with frequency domain equalization have similar performance, efficiency, and low signal processing complexity advantages as OFDM, and in addition are less sensitive than OFDM to RF impairments such as power amplifier nonlinearities. We discuss similarities and differences of SC and OFDM systems and coexistence possibilities, and present examples of SC-FDE performance capabilities.
Citations
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01 Sep 2016
TL;DR: A novel channel estimator for ZT DFT-s-OFDM is proposed which circumvents limitations by enabling the correlation of the received signal against the original sequence rather than its zero-padded version, and results prove the benefits in terms of mean square error (MSE) of the proposed channel estimators with respect to existing solutions.
Abstract: Zero-tail Discrete Fourier Transform-spread-Orthogonal Frequency Division Multiplexing (ZT DFT-s-OFDM) waveform is considered as an attractive candidate for a 5th Generation (5G) radio access technology given its flexibility and spectral containment properties. However, high quality channel estimation in ZT DFT-s-OFDM is compromised by the necessity of accommodating a zero head/tail in the transmit signal. This zero-insertion affects negatively reference sequence properties such as cyclic zero-autocorrelation and flat frequency response. In this paper, we propose a novel channel estimator for ZT DFT-s-OFDM which circumvents such limitations by enabling the correlation of the received signal against the original sequence rather than its zero-padded version. Simulation results prove the benefits in terms of mean square error (MSE) of the proposed channel estimator with respect to existing solutions.
9Â citations
Cites background from "Frequency domain equalization for s..."
...Equalization is then usually performed in the frequency domain given the computational complexity benefits [6]....
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TL;DR: Simulation results show that the proposed system with iterative receiver structure provides considerable performance gains over conventional MIMO techniques, thus improving error performance and increasing spectral efficiency compared to conventional spatial multiplexing and transmit diversity techniques, respectively.
Abstract: This letter proposes a multiple-input multiple-output (MIMO) technique for single carrier frequency-domain equalization (SC-FDE). The proposed system achieves spatial multiplexing and transmit diversity gains altogether, thus improving error performance and increasing spectral efficiency compared to conventional spatial multiplexing and transmit diversity techniques, respectively. In order to achieve both of the gains, independent data streams are transmitted simultaneously through all transmit antennas with different cyclic delay patterns for each data stream. Corresponding receiver structure is also presented, where a successive interference cancellation (SIC) algorithm without ordering process is introduced. Simulation results show that the proposed system with iterative receiver structure provides considerable performance gains over conventional MIMO techniques.
9Â citations
Cites background from "Frequency domain equalization for s..."
...Note that the proposed MIMO technique can also be applied to OFDM systems....
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...I. INTRODUCTION S INGLE-carrier frequency-domain equalization (SC-FDE)has similar performance and essentially the same overall complexity as orthogonal frequency division multiplexing (OFDM) [1]....
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...S INGLE-carrier frequency-domain equalization (SC-FDE) has similar performance and essentially the same overall complexity as orthogonal frequency division multiplexing (OFDM) [1]....
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...Recently, the SC-FDE has drawn a great attention as an alternative to the OFDM, especially in the uplink communications, because its transmit structure at mobile equipment is very simple and lower peak-to-average power ratio (PAPR) significantly benefits the transmitter in terms of power efficiency....
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01 Oct 2010
TL;DR: This paper considers joint detection and channel estimation for SC-FDE schemes where a coarse channel estimate is obtained with the help of a training sequence and they employ iterative receivers where for each iteration the data estimates are used to improve the channel estimates.
Abstract: SC-FDE (Single-Carrier with Frequency-Domain Equalization) block transmission technique can have excellent performance in severely time-dispersive channels provided that accurate channel estimates are available at the receiver. In this paper we consider joint detection and channel estimation for SC-FDE schemes where a coarse channel estimate is obtained with the help of a training sequence and we employ iterative receivers where for each iteration the data estimates are used to improve the channel estimates. However, since the frequency-domain data blocks can have large envelope fluctuations, a decision-directed channel estimation might have significant noise enhancement effects. To overcome this problem, we combine channel estimates based on the training sequence with decision-directed channel estimates. Our performance results show that these techniques allow good performances without requiring high-power pilots or training blocks.
9Â citations
Cites methods from "Frequency domain equalization for s..."
...INTRODUCTION Block transmission techniques, with appropriate cyclic prefixes and employing FDE techniques (Frequency-Domain Equalization), are suitable to broadband wireless systems [1], [2]....
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01 Nov 2007
TL;DR: This paper investigates the performance degradation as a function of various circuit parameters for multi- carrier (MC) and single-carrier (SC) schemes, which can be useful for performing a system cost and performance tradeoff comparison and identifying main performance bottle necks for MC and SC based systems.
Abstract: The 60 GHz band, with a large unlicensed bandwidth, is an excellent choice for short distance high-speed communications. However, radio frequency (RF) circuit limitations at 60 GHz give rise to impairments such as phase noise, in-phase/quadrature-phase (I/Q) imbalance and amplifier nonlinearities. The candidate transmission schemes, in addition to multi-path fading, should therefore be fairly robust against RF circuit imperfections. This paper investigates the performance degradation as a function of various circuit parameters for multi-carrier (MC) and single-carrier (SC) schemes, which can be useful for:( i) performing a system cost and performance tradeoff comparison, (ii) identifying main performance bottle necks for MC and SC based systems.
9Â citations
Cites background from "Frequency domain equalization for s..."
...equalization (FDE) [1]....
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...While both schemes can counter inter-symbolinterference (ISI) at a reasonable implementation complexity [1], they have different tolerances to RF circuit imperfections....
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...ization (FDE) [1], their overall system complexity and a LOS 60 GHz transmission channel model....
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19 May 2008
TL;DR: In this article, the authors considered the frequency-domain channel equalization and symbol detection of multiple input multiple output (MIMO) single-carrier broadband wireless system in the presence of severe frequency-selective channel fading and multiple unknown carrier frequency offsets (CFOs).
Abstract: We consider the frequency-domain channel equalization and symbol detection of multiple input multiple output (MIMO) single-carrier broadband wireless system in the presence of severe frequency-selective channel fading and multiple unknown carrier frequency offsets (CFOs). We show that the constellation of the equalized data is rotating due to multiple CFOs, therefore, the equalized data can not be reliably detected without removing the rotating phases caused by the multiple unknown CFOs. Instead of estimating the CFOs, we propose a method to estimate the rotating phases caused by multiple CFOs, remove the rotating phases from the equalized data, and perform symbol detection. Numerical example indicates that the proposed method provide very good results for a 4 times 2 wireless system with 8PSK modulation and 75-tap Rayleigh fading channels.
9Â citations
References
More filters
Book•
01 Jan 1986
TL;DR: In this paper, the authors propose a recursive least square adaptive filter (RLF) based on the Kalman filter, which is used as the unifying base for RLS Filters.
Abstract: Background and Overview. 1. Stochastic Processes and Models. 2. Wiener Filters. 3. Linear Prediction. 4. Method of Steepest Descent. 5. Least-Mean-Square Adaptive Filters. 6. Normalized Least-Mean-Square Adaptive Filters. 7. Transform-Domain and Sub-Band Adaptive Filters. 8. Method of Least Squares. 9. Recursive Least-Square Adaptive Filters. 10. Kalman Filters as the Unifying Bases for RLS Filters. 11. Square-Root Adaptive Filters. 12. Order-Recursive Adaptive Filters. 13. Finite-Precision Effects. 14. Tracking of Time-Varying Systems. 15. Adaptive Filters Using Infinite-Duration Impulse Response Structures. 16. Blind Deconvolution. 17. Back-Propagation Learning. Epilogue. Appendix A. Complex Variables. Appendix B. Differentiation with Respect to a Vector. Appendix C. Method of Lagrange Multipliers. Appendix D. Estimation Theory. Appendix E. Eigenanalysis. Appendix F. Rotations and Reflections. Appendix G. Complex Wishart Distribution. Glossary. Abbreviations. Principal Symbols. Bibliography. Index.
16,062Â citations
"Frequency domain equalization for s..." refers methods in this paper
...Adaptation can be done with LMS (least mean square), RLS, or least squares minimization (LS) techniques, analogous to adaptation of time domain equalizers [Hay96], [Cla98]....
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...Overlap-save or overlap-add signal processing techniques could also be used to avoid the extra overhead of the cyclic prefix [Fer85], [Hay96]....
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TL;DR: The analysis and simulation of a technique for combating the effects of multipath propagation and cochannel interference on a narrow-band digital mobile channel using the discrete Fourier transform to orthogonally frequency multiplex many narrow subchannels, each signaling at a very low rate, into one high-rate channel is discussed.
Abstract: This paper discusses the analysis and simulation of a technique for combating the effects of multipath propagation and cochannel interference on a narrow-band digital mobile channel. This system uses the discrete Fourier transform to orthogonally frequency multiplex many narrow subchannels, each signaling at a very low rate, into one high-rate channel. When this technique is used with pilot-based correction, the effects of flat Rayleigh fading can be reduced significantly. An improvement in signal-to-interference ratio of 6 dB can be obtained over the bursty Rayleigh channel. In addition, with each subchannel signaling at a low rate, this technique can provide added protection against delay spread. To enhance the behavior of the technique in a heavily frequency-selective environment, interpolated pilots are used. A frequency offset reference scheme is employed for the pilots to improve protection against cochannel interference.
2,627Â citations
"Frequency domain equalization for s..." refers background in this paper
...OFDM transmits multiple modulated subcarriers in parallel [ 1 ]....
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...Several variations of orthogonal frequency-division multiplexing (OFDM) have been proposed as effective anti-multipath techniques, primarily because of the favorable trade-off they offer between performance in severe multipath and signal processing complexity [ 1 ]....
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TL;DR: In this contribution the transmission of M-PSK and M-QAM modulated orthogonal frequency division multiplexed (OFDM) signals over an additive white Gaussian noise (AWGN) channel is considered and the degradation of the bit error rate is evaluated.
Abstract: In this contribution the transmission of M-PSK and M-QAM modulated orthogonal frequency division multiplexed (OFDM) signals over an additive white Gaussian noise (AWGN) channel is considered. The degradation of the bit error rate (BER), caused by the presence of carrier frequency offset and carrier phase noise is analytically evaluated. It is shown that for a given BER degradation, the values of the frequency offset and the linewidth of the carrier generator that are allowed for OFDM are orders of magnitude smaller than for single carrier systems carrying the same bit rate. >
1,816Â citations
TL;DR: This correspondence describes the construction of complex codes of the form exp i \alpha_k whose discrete circular autocorrelations are zero for all nonzero lags.
Abstract: This correspondence describes the construction of complex codes of the form exp i \alpha_k whose discrete circular autocorrelations are zero for all nonzero lags. There is no restriction on code lengths.
1,624Â citations