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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26 Dec 2007
TL;DR: A new approach for frequency-domain equalization of continuous phase modulated (CPM) signals is presented, which separates channel equalization on the one hand and CPM demodulation on the other to calculate independently of the CPM scheme a new low-complexity zero-forcing channel equalizer.
Abstract: A new approach for frequency-domain equalization of continuous phase modulated (CPM) signals is presented. In contrast with state-of-the-art receivers, we separate channel equalization on the one hand and CPM demodulation on the other. This separation enables us to calculate independently of the CPM scheme a new low-complexity zero-forcing channel equalizer. We also present a new high-performance minimum mean square error (MMSE) channel equalizer for any CPM scheme and a method to lower its complexity for a popular class of CPM schemes. Simulations show that our new MMSE equalizer significantly outperforms state-of-the-art linear receivers in a 60 GHz multipath environment.
7 citations
Cites background or methods from "Frequency domain equalization for s..."
...We consider a block-based communication system, where a cyclic prefix (CP) is attached to each transmitted block a to enable low-complexity equalization in the FD [2]....
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...Equalizing such channels in the frequency domain (FD) rather than in the time domain (TD) can significantly lower the computational complexity of the system [2]....
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...They have a perfectly constant envelope which makes them much more favorable than Orthogonal Frequency Division Multiplexing (OFDM) as cheap, power efficient nonlinear PA’s can be used instead of expensive, inefficient linear ones [2]....
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01 May 2004
TL;DR: In this article, adaptive coding is proposed for application in conjunction with adaptive sub-band allocation (ASBA) for MC-CDMA/FDMA systems, which is proved to yield a significant performance improvement, especially if a user-service prioritisation is considered in the ASBA.
Abstract: The MC-CDMA/FDMA scheme is a candidate for the air-interface of beyond 3G mobile communications. An efficient adaptive sub-band allocation (ASBA) approach has been recently shown to provide a considerable gain in the uncoded system performance. In this paper, adaptive coding is proposed for application in conjunction with ASBA. This is proved to yield a significant performance improvement, especially if a user-service prioritisation is considered in the ASBA.
7 citations
Cites methods from "Frequency domain equalization for s..."
...However, in this respect, some single carrier solutions employing frequency domain equalisation have been recently shown to represent valid alternatives to OFDM [ 2 ]....
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01 Jan 2011
TL;DR: The performance results obtained when modeling the density function by a weighted sum of Gaussians with those obtained with a single Gaussian using a SC-FDE (Single Carrier-Frequency Domain Equalizer) scheme are compared.
Abstract: A solution for the problem of estimating the PN (Phase Noise) from the observation of the channel output in burst communications is to establish a state-model for the PN and determine the a posteriori probability density function (pdf) of the state conditioned on all measurement data, thus providing the means to compute an optimal estimate with respect to any criterion, e.g., Minimum Mean-Squared Error (MMSE). However, except in the Gaussian case, it is extremely difficult to determine and propagate this density function. As a result,and since the observation model of the PN is non-linear, the a posteriori pdf becomes non-Gaussian, and a sub-optimal solution for the problem must be found. In this paper we approximate the non-Gaussian pdf by a weighted sum of Gaussians. Additionally, we compare the performance results obtained when modeling the density function by a weighted sum of Gaussians with those obtained with a single Gaussian using a SC-FDE (Single Carrier-Frequency Domain Equalizer) scheme.
7 citations
Cites background from "Frequency domain equalization for s..."
..., from the Mobile Terminal (MT) to the Base Station (BS), and experiences a lower Peakto-Average Power Ratio (PAPR), enabling the use of nonlinear power amplifiers [3], [4]....
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28 Jul 2014
TL;DR: A simple SC-FDE Packet Error Rate analytical model using FTN signaling, based on the Iterative Block with Decision Feedback Equalization technique, which achieves a performance similar to Nyquist signaling.
Abstract: Current wireless communication systems rely on the assumptions of the Nyquist theorem. Faster-Than-Nyquist (FTN) assumes that a bandwidth below the Nyquist bandwidth can be used with minimum loss, however the existing receivers are too complex. Single Carrier with Frequency-Domain Equalization (SC-FDE) has been proposed to handle multipath dispersive broadband channels, however the uplink of SC-FDE can be severely affected by deep-fades and/or poor channel conditions. To cope with such difficulties Diversity Combining (DC) Hybrid ARQ is a viable technique, since it combines the several packet copies sent by a Mobile Terminal to create reliable packet symbols at the receiver. This paper proposes a simple SC-FDE Packet Error Rate analytical model using FTN signaling, based on the Iterative Block with Decision Feedback Equalization technique, which achieves a performance similar to Nyquist signaling.
7 citations
Cites methods from "Frequency domain equalization for s..."
...Block transmission techniques combined with Frequency-Domain Equalization (FDE) such as Orthogonal Frequency Division Multiplexing (OFDM) [2] and Single-Carrier with FDE (SCFDE) [8] are widely recognized as the best candidates for the downlink and uplink, respectively [9], [10]....
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01 Oct 2006
TL;DR: It is shown that linear equalizers lose all frequency diversity in the classical outage-rate trade-off, except at constant rate, and decision-feedback equalizers on the other hand allow to capture most of the spatiofrequential diversity.
Abstract: The diversity-rate tradeoff was introduced by Zheng and Tse for ML reception in frequency-flat MIMO channels. Since then, some results have been obtained also for the diversity behavior of suboptimal receivers such as linear and decision-feedback equalizers for frequency-selective SIMO channels. However, these results are limited to infinite length equalizers or cyclic prefix systems. In this paper we analyze the diversity of more practical FIR equalizers. We show in particular that linear equalizers lose all frequency diversity in the classical outage-rate trade-off, except at constant rate. Decision-feedback equalizers on the other hand, even if equipped with FIR filters, allow to capture most of the spatiofrequential diversity.
7 citations
Cites background from "Frequency domain equalization for s..."
...The use of the DFE appears in [11] (FIR) and [12],[13] (SC-CP) where in the last two references diversity behavior is investigated through simulations....
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...The problem of in nite length non-causal feedforward lters (FFFs) in the DFE can be overcome by introducing a CP and performing the FFF’ing in the frequency domain (SC-CP) and the feedback ltering in the time domain, see [12],[13] (where oversampling leads to increased DFT size which is not necessary)....
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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