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Journal ArticleDOI

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.

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Citations
More filters
01 Jan 2006
TL;DR: The proposed receiver is suitable for broadband wireless systems, with performances that can be close to the single-user MFB (Matched Filter Bound), even for fully loaded systems and/or in the presence of strong interfering signals.
Abstract: In this paper we consider the uplink transmission within CP-assisted (Cyclic Pre x) DS-CDMA (Direct Sequence Code Division Multiple Access) systems and we present a frequency-domain MUD (MultiUser Detection) receiver with iterative estimation and compensation of residual frequency errors. The proposed receiver is suitable for broadband wireless systems, with performances that can be close to the single-user MFB (Matched Filter Bound), even for fully loaded systems and/or in the presence of strong interfering signals. The receiver is powerful enough for typical asynchronous scenarios, requiring only a coarse synchronization between users.

1 citations


Cites methods from "Frequency domain equalization for s..."

  • ...CP-assisted (Cyclic Prefix) block transmission techniques are known to be appropriate for severely timedispersive channels, since they allow low-complexity, FFTbased (Fast Fourier Transform) receiver implementations [1, 2]....

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Proceedings ArticleDOI
01 Nov 2012
TL;DR: 2-step QRM-MLBD is applied to TS inserted SC (TS-SC) transmission in order to further reduce the complexity of QRM -MLBD and it is shown by computer simulation that 2-stepQRM- MLBD can reduce thecomplexity compared to conventional Q RM-ML BD while keeping almost the same BER performance.
Abstract: Near maximum likelihood block signal detection using QR decomposition and M-algorithm (QRM-MLBD) can improve a bit error rate (BER) performance of cyclic prefix inserted single-carrier (CP-SC) transmissions. However, it requires a fairly large number M of surviving paths in the M-algorithm and leads to very high computational complexity. Replacing the CP by training sequence (TS) was shown to reduce the number of M. Another approach to reduce the complexity of QRM-MLBD is to modify the tree structure constructed by QR decomposition for ML detection. Recently, we proposed a 2-step QRM-MLBD which prunes unreliable symbol candidates before tree search by using the minimum mean square error based frequency-domain equalization (MMSE-FDE) output. In this paper, we apply the 2-step QRM-MLBD to TS inserted SC (TS-SC) transmission in order to further reduce the complexity of QRM-MLBD. We show by computer simulation that 2-step QRM-MLBD can reduce the complexity compared to conventional QRM-MLBD while keeping almost the same BER performance.

1 citations


Cites background from "Frequency domain equalization for s..."

  • ...A cyclic prefix inserted SC (CP-SC) block transmission with minimum mean square error based frequency-domain equalization (MMSE-FDE) can improve the BER performance of CP-SC transmission with a low computational complexity [2, 3]....

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  • ...2-STEP QRM-MLBD FOR TS-SC TRANSMISSION...

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Proceedings ArticleDOI
01 Dec 2011
TL;DR: By applying the proposed iterative DFCE in the turbo SIC, the required average received signal-to-noise power ratio (SNR) at the average block error rate (BLER) of 10−2 is decreased and the ICI due to non-orthogonality in the QO-STBC improves, which leads to improvement in the achievable performance.
Abstract: This paper proposes using iterative decision-feedback channel estimation (DFCE) in a turbo soft interference canceller (SIC) for a quasi-orthogonal (QO) - space-time block code (STBC) with four antennas in discrete Fourier transform (DFT)-precoded orthogonal frequency division multiple access (OFDMA). In the proposed method, channel estimation (CE) is updated at each turbo SIC iteration loop by using soft-symbol estimation based on the log-likelihood ratio (LLR) of an extrinsic probability at the Max-Log-MAP (maximum a posteriori probability) decoder output. Hence, the accuracy of the generated residual inter-code interference (ICI) due to non-orthogonality in the QO-STBC improves in the turbo SIC, which leads to improvement in the achievable performance. Computer simulation results show that by applying the proposed iterative DFCE in the turbo SIC, the required average received signal-to-noise power ratio (SNR) at the average block error rate (BLER) of 10−2 is decreased by approximately 1.5 and 1.0 dB compared to those for STBC using reference signal (RS) based CE and DFCE, respectively, for the coding rate of R = 1/3 in turbo code. Hence, the iterative DFCE works cooperatively in the turbo SIC to decrease the ICI in the full rate QO-STBC.

1 citations

Journal ArticleDOI
Liang Dong1
TL;DR: Simulation results show superior receiving performance of the proposed system compared with the OFDM system with a similar complexity.
Abstract: Single-carrier block transmission is an alternative scheme to orthogonal frequency-division multiplexing (OFDM) for wireless broadband communications. In this paper, a receiver is designed for single-carrier block transmission with cyclic prefix for mobile broadband communications. As the wireless transmission is over doubly selective channels, a basis expansion model is used to capture both the time- and frequency-selectivity of the channel and is parameterized for the receiver design. The receiver estimates the channel model coefficients in the time domain and uses these coefficients for equalization in the frequency domain. The channel estimation is assisted by time-domain pilot insertion. The structure of the frequency-domain channel matrix is exploited and a linear minimum mean-square error equalizer is used for the equalization. When the basis expansion model well matches the physical channel, simulation results show superior receiving performance of the proposed system compared with the OFDM system with a similar complexity.

1 citations

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.

1 citations


Cites background from "Frequency domain equalization for s..."

  • ...Single Carrier frequency domain equalization (SC-FDE) has been shown to be an attractive scheme for broadband wireless channels which have long response memory [1, 2]....

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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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Journal ArticleDOI
Jr. L.J. Cimini1
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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Book
Simon Haykin1
01 Mar 1991

2,447 citations

Journal ArticleDOI
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

Journal ArticleDOI
D. Chu1
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