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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
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Proceedings ArticleDOI
11 Jul 2004
TL;DR: A class of SC-FDE receivers for a layered space-time architecture (LST) with a hybrid structure with frequency domain feedforward and time domain feedback filters is introduced.
Abstract: Single carrier modulations (SC) combined with frequency domain equalization (FDE) techniques have been shown to be a valuable alternative to the popular OFDM modulations, especially in regard to its robustness to RF implementation impairments. We introduce a class of SC-FDE receivers for a layered space-time architecture (LST). These receivers have a hybrid structure with frequency domain feedforward and time domain feedback filters. The performance of the proposed receivers are evaluated for severe time-dispersive channels.

18 citations

Journal ArticleDOI
TL;DR: In this paper, the authors proposed asymmetric orthogonal frequency-division multiplexing (OFDM) systems that bridge general OFDM and single carrier systems, and showed how effects of noise enhancement and frequency diversity counteract each other in asymmetric OFDM systems.
Abstract: In this letter, we first extend the convolution theory of discrete Fourier transform (DFT) and introduce a structure of layered fast Fourier transform (FFT). Based on this framework, we propose novel asymmetric orthogonal frequency-division multiplexing (OFDM) systems that bridge general OFDM and single carrier systems. Adaptive to the capability of the transceiver, asymmetric OFDM systems provide significant flexibility in system design and operation. We show how effects of noise enhancement and frequency diversity counteract each other in asymmetric OFDM systems. Performance comparison with general OFDM and single carrier systems is also given.

18 citations

Proceedings ArticleDOI
19 May 2008
TL;DR: This work presents a new symbol block construction which yields a cyclic continuous phase modulated (CPM) signal to enable frequency domain equalization, and proposes a new subblock, called intrafix, valid for any CPM scheme.
Abstract: We present a new symbol block construction which yields a cyclic continuous phase modulated (CPM) signal to enable frequency domain equalization. It is known that in addition to a cyclic prefix, a subblock of data-dependent symbols has to be inserted in each block to cope with the memory in the CPM signal. We propose a new subblock, called intrafix, valid for any CPM scheme. Our intrafix is shorter than what is currently known in the literature, reducing the overhead. Moreover, it can be calculated on a per-block basis, without knowledge of previous blocks. We also prove that there are constraints on the length of both the intrafix and the total block by studying the influence of the modulation index. Simulation results in a 60 GHz environment show that our new block construction satisfies all requirements.

18 citations


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

  • ...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, power inefficient linear ones [2]....

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  • ...The channel can then be equalized in the FD with one complex multiplication per sample [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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Proceedings ArticleDOI
06 Mar 2011
TL;DR: Two FDE configurations for coherent optical transmission over fiber-optic channels are presented and some applications are also described.
Abstract: Frequency-domain equalization (FDE) has been attracting much attention for high-speed long-haul transmission over fiber-optic channels. Two FDE configurations for coherent optical transmission are presented and some applications are also described.

18 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.

16,062 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