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: In this article, a transmission of 112(4×28)-b/s PAM-4 signal is experimentally demonstrated within only 50GHz grid, achieving an optical spectral efficiency (SE) of 2.24 b/s/Hz.
4 citations
30 Oct 2009
TL;DR: UWB (Ultra Wide Band) systems employing SC-FDE techniques in the presence of strong interference signals that occupy a significant part of the transmission band are considered and a suitable soft combining ARQ schemes are proposed.
Abstract: SC-FDE (Single-Carrier with Frequency-Domain Equalization) together with soft packet combining ARQ techniques (Automatic Repeat reQuest) was shown to be effective for broadband wireless systems with deep fading effects such as those inherent to shadowing. However, they are not suitable to cope with strong interference effects, especially when the channel remains fixed. In this paper, we consider UWB (Ultra Wide Band) systems employing SC-FDE techniques in the presence of strong interference signals that occupy a significant part of the transmission band and we propose suitable soft combining ARQ schemes. Our techniques are able to cope with strong interference levels as well as deep fading, even for fixed channels.
4 citations
01 Nov 2015
TL;DR: A 3-tap Adaptive Frequency Domain Decision Feedback Equalizer (AFD- DFE) is designed in this work by exploiting the banded and sparse structure of the equivalent channel matrix to mitigate Inter-Carrier Interference (ICI) due to large Carrier Frequency Offset (CFO).
Abstract: To mitigate Inter-Carrier Interference (ICI) due to large Carrier Frequency Offset (CFO) in an uplink Single- Carrier Frequency Division Multiple Access system, a 3-tap Adaptive Frequency Domain Decision Feedback Equalizer (AFD- DFE) is designed in this work by exploiting the banded and sparse structure of the equivalent channel matrix. The block Recursive Least Squares (RLS) algorithm is used for adaptation and both the feedforward and feedback filters are implemented in the frequency-domain. Consequently, the complexity of the block RLS, by exploiting the matrix structure in the frequency-domain, is reduced substantially when compared to its time-domain counterpart. Ultimately, it will be shown that the proposed AFD- DFE exhibits significant excellent performance improvement when compared to a 1-tap AFD-DFE while still enjoying a low computational complexity.
4 citations
Cites background from "Frequency domain equalization for s..."
...Recently, unlike those in [4]–[9] adaptive equalization schemes (RLS [10]/Particle Swarm Optimization (PSO) [11] based) are proposed for SC-FDMA system [12]–[14] and impressive performance gains are achieved....
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...Several works studied the frequency-domain DFE [4]–[9]....
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24 Oct 2008
TL;DR: Simulation results show that the proposed new training sequence structure for channel estimation to reduce the estimation errors caused by residual CFO can efficiently reduce the channel estimation errors in FDE system, and improve the system performance.
Abstract: Frequency domain equalization (FDE) is an attractive solution for wireless broadband transmission because of its strong capability in handling multipath environment. However, frequency domain channel estimation suffers from the inter-carrier interference(ICI) caused by carrier frequency offset (CFO). In this paper, we proposed new training sequence structure for channel estimation to reduce the estimation errors caused by residual CFO. The proposed new training sequence structure can be easily obtained from any existing channel training sequences without introducing significant changes to their original property. Simulation results show that, this scheme can efficiently reduce the channel estimation errors in FDE system, and improve the system performance.
4 citations
Cites background from "Frequency domain equalization for s..."
...SC-FDE technique attracts more and more attention from both research and practical fields due to its low complexity equalization and the signals’ low peak to average power ratio (PAPR) [1]....
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...For detailed information of SC-FDE systems, the readers are referred to [1]....
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20 Jul 2008
TL;DR: The experimental results reveal the superiority of the BCH (15, 7) code to all other coding schemes if a large redundancy is accepted and the issue of redundancy is of major concern, the Hamming (7,4) code is the best.
Abstract: It is known that Bluetooth systems employ a Hamming (15, 10) code for error correction. In this paper, we propose different error correction coding schemes for this purpose. A comparison study between the Hamming (7, 4), the cyclic (15, 11) and the BCH (15, 7) codes is held in the paper to choose an alternative to the Hamming (15, 10) code. The simulation experiments are held over both an Additive White Gaussian Noise (AWGN) channel and a Rayleigh fading channel. The experimental results reveal the superiority of the BCH (15, 7) code to all other coding schemes if a large redundancy is accepted. If the issue of redundancy is of major concern, the Hamming (7,4) code is the best.
4 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