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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TL;DR: This study presents a multiple-input multiple-output (MIMO) architecture utilising polarisation diversity to increase the capacity of high-frequency (HF) radio links through the ionospheric channel, and introduces the original idea of diversity in the transmitted polarisations to replace the classical space diversity for MIMO applications.
Abstract: This study presents a multiple-input multiple-output (MIMO) architecture utilising polarisation diversity to increase the capacity of high-frequency (HF) radio links through the ionospheric channel. A summary of physics focuses on the polarisation of radio waves propagated in the ionosphere. This preliminary step introduces the original idea of diversity in the transmitted polarisations to replace the classical space diversity for MIMO applications. This solution enables a reduction of the inter antenna spacing which is convenient in the context of decametric wavelengths. Simulations, referring to the theoretical expression of channel capacity and involving realistic models of ionospheric radio links, underline a significant increase in performances for this particular MIMO structure if compared to a single-input single-output system. Additionally, the trade-off between capacity gain and complexity appears balanced with the development of a 2 x N MIMO system transmitting two complementary circular polarisations. More specifically, the design of a 2 x 2 MIMO system is described in the context of a single carrier waveform and frequency-domain equalisation, resorting to classical solutions for the different signal processing modules. A global simulation, involving the entire transmission system, is carried out and gives an estimate of the maximal data transfer rate compatible with a requested quality of service.
11 citations
20 Jun 2004
TL;DR: In this article, the authors investigate the meaning of decision feedback equalization for a single carrier system with frequency domain equalization in an overall system approach, based on the parameters of the IEEE 802.11a standard.
Abstract: In this work we investigate the meaning of decision feedback equalization for a single carrier system with frequency domain equalization (SC/FDE) in an overall system approach, based on the parameters of the IEEE 802.11a standard. The concept of SC/FDE allows an advantageous combination of feed forward frequency domain equalization and feed back equalization in the time domain, that combines low signal processing complexity and powerful equalization. Although the concept of decision feedback equalization (DFE) is a well known and developed theory, this nonlinear equalization is rarely investigated in an overall system approach. Based on that the possible performance gain will be characterized under the constraints of channel characteristics, error propagation, higher order modulation schemes and channel coding. It will be demonstrated that these elements have significant influence on the possible performance of DFE and may reduce the propagated high performance gain.
11 citations
TL;DR: This letter designs iterative receiver algorithms for joint frequency-domain equalization and decoding in a single carrier system assuming perfect channel state information and proposes two receiver algorithms with, respectively, parallel and sequential message-passing schedules in the MF part.
Abstract: In this letter, we design iterative receiver algorithms for joint frequency-domain equalization and decoding in a single carrier system assuming perfect channel state information. Based on an approximate inference framework that combines belief propagation (BP) and the mean field (MF) approximation, we propose two receiver algorithms with, respectively, parallel and sequential message-passing schedules in the MF part. A recently proposed receiver based on generalized approximate message passing (GAMP) is used as a benchmarking reference. The simulation results show that the BP-MF receiver with sequential passing of messages achieves the best BER performance at the expense of higher computational complexity compared to that of the GAMP receiver. The parallel BP-MF receiver has complexity similar to that of GAMP, but its low convergence rate yields poor performance, especially under high signal-to-noise ratio conditions.
11 citations
Cites background from "Frequency domain equalization for s..."
...It has theperformance, efficiencyand lowcomplexityadvantagesover itsorthogonal frequency division multiplexing (OFDM) counterpart, while being less sensitive to power amplifier nonlinearities and carrier frequency offsets, in addition to exhibiting a lower peak-to-average transmitted power ratio [1]....
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TL;DR: A comparison of pre and post-processing methodology, using the same algorithms for the use of massive multiple input, multiple output (MIMO) combined with single-carrier with frequency-domain equalization (SC-FDE) modulations, associated to millimeter wave (mm-Wave) communications using precoding.
11 citations
TL;DR: Computer simulation shows that the throughput performance of SCFDE is superior to that of OFDM around the edge of the service area when both amplifier nonlinearity and adaptive modulation and coding are taken into account.
Abstract: The throughput performance of single-carrier transmission with frequency-domain equalisation (SCFDE) and of orthogonal frequency division multiplexing (OFDM) in a nonlinear fading channel are compared. Their transmission performance when transmission power control (TPC) is used with adaptive modulation and coding is presented. Computer simulation shows that the throughput performance of SCFDE is superior to that of OFDM around the edge of the service area when both amplifier nonlinearity and adaptive modulation and coding are taken into account.
11 citations
References
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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