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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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Patent
16 Apr 2015
TL;DR: In this article, a backhaul radio that operates in multipath propagation environments such as obstructed LOS conditions with uncoordinated interference sources in the same operating band is disclosed.
Abstract: A backhaul radio is disclosed that operates in multipath propagation environments such as obstructed LOS conditions with uncoordinated interference sources in the same operating band. Such a backhaul radio may use a combination of interference mitigation procedures across multiple of the frequency, time, spatial and cancellation domains. Such backhaul radios may communicate with each other to coordinate radio resource allocations such that accurate interference assessment and channel propagation characteristics assessment may be determined during normal operation.

37 citations

Journal ArticleDOI
TL;DR: A survey and tutorial is provided on the subject of multiple-input-multiple-output (MIMO) multicarrier (MC) systems relying on the space-time shift keying (STSK) concept, followed by the design of STSK systems in the context of MC modulation-based transmissions over dispersive wireless channels.
Abstract: A survey and tutorial is provided on the subject of multiple-input–multiple-output (MIMO) multicarrier (MC) systems relying on the space–time shift keying (STSK) concept. We commence with a brief review of the family of MIMO systems, which is followed by the design of STSK systems in the context of MC modulation-based transmissions over dispersive wireless channels. Specifically, the STSK scheme is amalgamated with orthogonal frequency-division multiplexing, MC code-division multiple access, orthogonal frequency-division multiple access (OFDMA), and single-carrier frequency-division multiple access. We also provide a rudimentary introduction to MC differential STSK employing both conventional differential detection and multiple-symbol differential sphere decoding for the sake of dispensing with channel estimation. We conclude with the design recipes of coherent versus noncoherent MC STSK schemes, complemented by a range of future research ideas.

37 citations

Journal ArticleDOI
TL;DR: These receivers have a hybrid structure with frequency-domain feedforward and time-domain feedback filters for intersymbol interference (ISI) and interference cancellation, and show the superiority of MIMO-SC approaches relative to MIMo-OFDM in terms of the BER performance for the simulated scenarios.
Abstract: Block transmission techniques, with appropriate cyclic prefix and frequency-domain processing schemes, have been shown to be excellent candidates for digital transmission over severely time-dispersive channels, allowing good performance with implementation complexity that is much lower than traditional time-domain processing schemes. Orthogonal frequency-division multiplexing (OFDM) modulation is the most popular block transmission technique. Single-carrier (SC) modulation using frequency-domain equalization (FDE) is an attractive alternative approach based on this principle. In this paper, we propose two new receiver structures for multiple-input-multiple-output (MIMO) channels employing SC (MIMO-SC) modulation and FDE schemes. These receivers have a hybrid structure with frequency-domain feedforward and time-domain feedback filters for intersymbol interference (ISI) and interference cancellation. The proposed schemes are compared with different MIMO systems employing OFDM modulation (MIMO-OFDM) receivers in terms of performance [bit error rate (BER) and throughput] and complexity. Our performance results show the superiority of MIMO-SC approaches relative to MIMO-OFDM in terms of the BER performance for the simulated scenarios. Also, the simulation results show that the proposed hybrid MIMO-SC receivers yield a higher throughput than a MIMO-OFDM system.

37 citations


Cites background or methods or result from "Frequency domain equalization for s..."

  • ...For this reason, a hybrid time-frequency SC-FDE was proposed in [2] and [9], employing a frequencydomain feedforward filter and a short time-domain feedback filter....

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  • ...This observation is different from the observation in [2], which shows for single-input–single-output systems and for low code rates that OFDM performance is slightly better than the SC....

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  • ...Single-carrier (SC) modulation using FDE techniques is another valuable candidate for highly dispersive channels in broadband wireless communications [2], [3]....

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Journal ArticleDOI
TL;DR: It is observed that fractionally spaced processing provides significant performance benefit, with a similar complexity to the symbol-rate system, when the baseband filtering is included.
Abstract: This paper investigates the use of complex-modulated oversampled filter banks (FBs) for frequency-domain equalization (FDE) in single-carrier systems. The key aspect is mildly frequency-selective subband processing instead of a simple complex gain factor per subband. Two alternative low-complexity linear equalizer structures with MSE criterion are considered for subband-wise equalization: a complex FIR filter structure and a cascade of a linear-phase FIR filter and an allpass filter. The simulation results indicate that in a broadband wireless channel the performance of the studied FB-FDE structures, with modest number of subbands, reaches or exceeds the performance of the widely used FFT-FDE system with cyclic prefix. Furthermore, FB-FDE can perform a significant part of the baseband channel selection filtering. It is thus observed that fractionally spaced processing provides significant performance benefit, with a similar complexity to the symbol-rate system, when the baseband filtering is included. In addition, FB-FDE effectively suppresses narrowband interference present in the signal band.

36 citations


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

  • ...In frequencydomain equalization, FSE can be done by doubling the number of subbands and the sampling rate at the filter bank input [1, 3, 6]....

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  • ...One central choice in the FDE design is between symbolspaced equalizers (SSE) and fractionally spaced equalizers (FSE) [3, 14]....

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Proceedings ArticleDOI
01 Dec 2003
TL;DR: This paper compares the theoretical performance of OFDM and SCFDE when each is implemented in one of two different multiple-input multiple-output (MIMO) architectures: spatial multiplexing and space-time block codes.
Abstract: Recent developments in orthogonal frequency division multiplexing (OFDM) and single-carrier frequency-domain equalization (SCFDE) have sparked debate about the superiority of one method over the other. In this paper, we further this debate by comparing the theoretical performance of OFDM and SCFDE when each is implemented in one of two different multiple-input multiple-output (MIMO) architectures: spatial multiplexing and space-time block codes. This study focuses on the use of MIMO-OFDM and MIMO-SCFDE in wireless local area network (WLAN) applications. Performance is given in terms of the packet error rate (PER) and the throughput of the systems.

36 citations


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

  • ...SCFDE, a PHY technique of similar complexity, has received much attention of late and has recently stimulated much “single-carrier vs multi-carrier” debate [2]....

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  • ...It is interesting to note that results published in [2] for single-input single-output (SISO) systems with linear equalization show that for a sufficiently strong channel code, OFDM systems outperform SCFDE systems....

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  • ...In [2], a comparison of these two technologies was conducted with a focus on single-antenna systems employed in fixed broadband wireless applications (IEEE 802....

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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