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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01 Nov 2010
TL;DR: Numerical results show the mutual information of SC APP system is better than that of OFDM system over UWB channels, though SC FDE alone causes capacity loss of SC system due to residual ISI of linear MMSE processing, so a hybrid nonlinear or iterative SC system to eliminate the residual ISI is indispensable.
Abstract: In terms of information theory, in this paper, the maximum achievable information rates of modulation systems are investigated over ultra wideband (UWB) multi-path channels where channel state is only known at the receiver. The capacity and mutual information of multi-carrier and single-carrier systems with digital modulation are compared using different UWB channel parameters. Assuming the inputs are i.i.d. equiprobable, the mutual information of SC systems is evaluated with frequency domain equalization (FDE) and with an a posteriori probability (APP) detector, respectively. The capacity of multi-carrier systems is evaluated with orthogonal frequency-division multiplexing (OFDM). Numerical results show the mutual information of SC APP system is better than that of OFDM system over UWB channels, though SC FDE alone causes capacity loss of SC system due to residual ISI of linear MMSE processing. Therefore, a hybrid nonlinear or iterative SC system to eliminate the residual ISI is indispensable.
3Â citations
Cites methods from "Frequency domain equalization for s..."
...Blockwise signal transmission and cyclic prefix (CP) to eliminate inter-block interference are also utilized in FDE [2]....
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05 Dec 2005
TL;DR: It is shown, by computer simulation, that pre-FDE transmission can provide significant improvement in the bit error rate (BER) performance in a frequency-selective Rayleigh fading channel and can achieve a BER performance close to that attainable by FDE reception.
Abstract: Severe frequency-selective fading, encountered in broadband wireless mobile communication, significantly degrades the single-carrier (SC) signal transmission performance. Multi-antenna frequency-domain pre-equalization (called pre-FDE) is presented for spread-spectrum single-carrier (SC) systems. At the transmitter, pre-FDE, with a transmit power constraint, is applied for each transmit antenna; no equalization function is necessary at the receiver. It is shown, by computer simulation, that pre-FDE transmission can provide significant improvement in the bit error rate (BER) performance in a frequency-selective Rayleigh fading channel and can achieve a BER performance close to that attainable by FDE reception. For a mobile communication system, the pre-FDE transmission for the downlink (base-to-mobile) and FDE reception for the uplink (mobile-to-base) can be implemented at a base station. This allows a simple implementation of mobile transceivers.
3Â citations
Cites background from "Frequency domain equalization for s..."
...MC-CDMA can exploit the channel frequency-selectivity by utilizing simple one-tap frequency-domain equalization (FDE)....
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16 Dec 2013
TL;DR: Simulation results show that the combination of HDFE and IC exhibits a reduction of the computational complexity and provides an efficient solution with good performance for IDMA systems in dispersive channels.
Abstract: A low complexity hybrid decision feedback equalization (HDFE) for single carrier interleave-division multiple-access SC-IDMA systems is considered for practical intersymbol interference (ISI) channels HDFE filters and interference canceller (IC) are used in conjunction with channel coding to cancel the channel impairments from a received data and generate feedback symbols whose reliability increases iteratively Moreover, the feedforward (FF) filter is implemented by Fast Fourier transforms (FFTs), which yields much lower computational complexity than equivalent structures, yet achieve the performance of such systems in time domain Simulation results including comparisons and compatibilities with those of frequency domain equalization (FDE) SC-FDE-IDMA and multi-carrier OFDM-IDMA schemes, with cyclic prefixing (CP) and zero padding (ZP) techniques, show that the combination of HDFE and IC exhibits a reduction of the computational complexity and provides an efficient solution with good performance for IDMA systems in dispersive channels
3Â citations
Cites background from "Frequency domain equalization for s..."
...In fact, the frequency-domain filtering must be performed on a per-block basis, while the feedback section must be fed with the previous detected symbols whose decisions are performed in the TD [4] [9]....
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TL;DR: This paper investigates the transceiver design for asymmetric UWB links with a single transmitter and a single receiver and reveals the similarity between the asymmetric UWB links and the conventional multiantenna systems.
Abstract: In recent years, Ultra-Wideband (UWB) technology has emerged as a promising physical layer candidate for a wide range of wireless networks, especially due to its low operation power level and coexistence ability with traditional wireless systems. However, none of these physical layer realizations has specified the compatible operation among them (see, e.g.,). Therefore, the effective interoperability between asymmetric UWB transceivers needs to be considered for ubiquitous wireless communications. In this paper, we investigate the transceiver design for asymmetric UWB links with a single transmitter and a single receiver. We consider factors that can lead to the asymmetry between UWB transmitters and receivers such as different numbers of signal bands and different pulse rates. Our analysis reveals the similarity between the asymmetric UWB links and the conventional multiantenna systems. Then, MIMO signal processing approaches can be readily applied to achieve the optimal design in terms of channel throughput or bit error rate (BER). Analysis and simulations corroborate the effectiveness of our transceiver designs.
3Â citations
28 Oct 2010
TL;DR: Simulation results show that the proposed scheme can utilize the available CSIT efficiently and achieve significant performance gain.
Abstract: In this paper, we study the transmission problem in multiple-input multiple-output (MIMO) systems with imperfect channel state information at the transmitter (CSIT). A scheme based on joint FEC coding and linear precoding at the transmitter and iterative linear minimum mean squared error (LMMSE) detection at the receiver is considered. The new scheme combines the advantages of beamforming, water-filling, and diversity coding. Simulation results show that the proposed scheme can utilize the available CSIT efficiently and achieve significant performance gain.
3Â 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.
16,062Â 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.
2,627Â 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. >
1,816Â 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.
1,624Â citations