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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TL;DR: This letter proposes a simple but effective way of improving the performance of channel estimation by implementing the proposed method with slightly additional computational complexity in PCP-SC and MIMO systems.
Abstract: The pilot cyclic prefixed single carrier (PCP-SC) system has the ability to achieve channel estimation in a fast-fading environment. It also enables symbol recovery even when the frequency domain of the channel has nulls. This letter proposes a simple but effective way of improving the performance of channel estimation. Regardless of the signal-to-noise ratio (SNR) and the pilot type, the receiver can achieve about a 1.72 dB performance gain for the mean squared error (MSE) of channel estimation if it implements the proposed method with slightly additional computational complexity. The proposed method can also be utilized in any type of pilot in PCP-SC and MIMO systems.
13 citations
08 Dec 2008
TL;DR: Computer simulation including extrinsic information transfer (EXIT) analysis confirms that the proposed scheme can achieve high frequency selection diversity and realize flexible frequency domain resource management.
Abstract: This paper proposes a spectrum-overlapped resource management (SORM) technique using a dynamic spectrum control (DSC) and turbo equalizer for flexible frequency domain resource management under multiuser conditions. In the proposed technique, discrete spectrum of the transmitted signal is mapped onto spectrum components having the highest channel gain in the system band while accepting partial spectrum overlapping between users, and a frequency domain soft-canceller with minimum mean square error (FD-SC/MMSE) turbo equalizer is applied as the signal detection scheme for multiuser detection (MUD) in order to cancel not only inter-symbol interference (ISI) but also inter-user interference (IUI). Computer simulation including extrinsic information transfer (EXIT) analysis confirms that the proposed scheme can achieve high frequency selection diversity and realize flexible frequency domain resource management.
13 citations
Cites background from "Frequency domain equalization for s..."
...The received signal can be generally equalized by a linear frequency domain equalization [4]....
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TL;DR: A low-complexity adaptive frequency-domain DFE (AFD-DFE) for single-carrier frequency-division multiple-access (SC-FDMA) systems, where both the feedforward and feedback filters operate in the frequency domain and are adapted using the well-known block recursive least squares (RLS) algorithm.
Abstract: It is well known that, in the case of highly frequency-selective fading channels, the linear equalizer (LE) can suffer significant performance degradation compared with the decision feedback equalizer (DFE). In this paper, we develop a low-complexity adaptive frequency-domain DFE (AFD-DFE) for single-carrier frequency-division multiple-access (SC-FDMA) systems, where both the feedforward and feedback filters operate in the frequency domain and are adapted using the well-known block recursive least squares (RLS) algorithm. Since this DFE operates entirely in the frequency domain, the complexity of the block RLS algorithm can be substantially reduced when compared with its time-domain counterpart by exploiting a matrix structure in the frequency domain. Furthermore, we extend our formulation to multiple-input–multiple-output (MIMO) SC-FDMA systems, where we show that the AFD-DFE enjoys a significant reduction in computational complexity when compared with the frequency-domain nonadaptive DFE. Finally, extensive simulations are carried out to demonstrate the robustness of our proposed AFD-DFE to high Doppler and carrier frequency offset (CFO).
13 citations
Cites methods from "Frequency domain equalization for s..."
...In [14]– [16], a hybrid DFE structure is used for SC-FDE systems to perform equalization in the frequency domain....
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01 Apr 2012
TL;DR: A robust and non-iterative scheme to enhance both the estimation of, and compensation for, the PHN process and this also includes channel estimation is proposed.
Abstract: In this paper we study the effect of phase noise (PHN) in a single carrier cyclic prefix (SCCP) system operating with a known cyclic prefix. The PHN process is a limiting factor in high throughput communication systems as higher-order constellations are extremely sensitive to it. In this paper we propose a robust and non-iterative scheme to enhance both the estimation of, and compensation for, the PHN process and this also includes channel estimation. In contrast to existing approaches for PHN compensation, in this paper we use a known cyclic prefix, pilot bins and interpolation over the PHN estimates. Simulation results show that the performance of SCCP with a known cyclic prefix is superior to SCCP systems with conventional compensation schemes in the moderate and higher SNR region for all values of PHN.
13 citations
Cites background from "Frequency domain equalization for s..."
...It finds application in LTE and was proposed as a physical layer interface for fourth generation wireless communication standards [1]....
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...These N + G values map directly onto the N + G estimates for the PHN across two symbols: φ̂ = [φ̂[N2 ], φ̂ [N2 + 1], · · · , φ̂[N +G−1], φ̂[0], φ̂[1], · · · , φ̂[N2 −1]], (see Fig....
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TL;DR: The proposed optimal precoder aims to optimize solution robustness against deterministic error perturbation and also minimize the mean-square error when the data mismatch is modeled as a white noise.
Abstract: Relying on nonredundant diagonal precoding and independent and identically distributed (iid) source assumption, this paper proposes a blind channel estimation scheme for single-carrier frequency-domain equalization-based space-time block coded systems The proposed method exploits the precoding-induced linear signal structure in the conjugate cross correlation between the two temporal block received signals as well as the circulant channel matrix property and can yield exact solutions whenever the channel noise is circularly Gaussian and the receive data statistic is perfectly obtained The channel estimation formulation builds on rearranging the set of linear equations relating the entries of conjugate cross-correlation matrix and products of channel impulse responses into one with a distinctive block-circulant with circulant-block (BCCB) structure This allows a simple identifiability condition depending on precoder parameters alone and also provides a natural yet effective optimal precoder design framework for improving solution accuracy when imperfect data estimation occurs We consider two models of data mismatch, from both deterministic and statistical points of view, and propose the associated design criteria The optimization problems are formulated to take advantage of the BCCB system matrix property and are solved analytically The proposed optimal precoder aims to optimize solution robustness against deterministic error perturbation and also minimize the mean-square error when the data mismatch is modeled as a white noise Pairwise error probability analysis is conducted for investigating the equalization performance Numerical examples are used to illustrate the performance of the proposed method
13 citations
Cites background from "Frequency domain equalization for s..."
...The price to be paid for this approach, however, would be the loss in the effective data rate....
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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.
16,062 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.
2,627 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. >
1,816 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.
1,624 citations