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
More filters
23 Apr 2012
TL;DR: The linear minimum mean square error (LMMSE) frequency domain equalization structure of TFI block transmission is presented and each diversity branch can be combined with maximum ratio and the diversity gain and bit error rate (BER) performance are analyzed in a theoretical way.
Abstract: The time-frequency interleave (TFI) diversity method for single carrier block transmission with frequency domain equalization (SC-FDE) has been proposed. For single antenna wireless communication systems, it can provide frequency diversity in frequency selective channels by interleaving and retransmitting. In this article, the linear minimum mean square error (LMMSE) frequency domain equalization structure of TFI block transmission is presented and each diversity branch can be combined with maximum ratio. The diversity gain and bit error rate (BER) performance are analyzed in a theoretical way. Both theoretical analysis and simulation results show that for TFI block transmission with LMMSE FDE, full diversity gain can be obtained. Compared to another full diversity achieving scheme direct sequence spread spectrum (DSSS), a better BER performance can be obtained.
1Â citations
Cites background from "Frequency domain equalization for s..."
...Compared to orthogonal frequency division multiplexing (OFDM), SC-FDE has similar performance and implementation complexity but lower peakto-average power ratio (PARR) and less sensitivity to carrier frequency offset [1]....
[...]
05 Dec 2005
TL;DR: A pilot-assisted iterative channel estimation that uses a pilot which is time-multiplexed within each chip block for fast Fourier transform (FFT) and acts as a cyclic-prefix of FFT block as well.
Abstract: As the channel frequency selectivity becomes severer, the bit error rate (BER) performance of direct sequence spread spectrum (DSSS) with rake combining degrades due to increasing inter-path interference. Frequency-domain equalization (FDE) can replace rake combining with much improved BER performance in a severe frequency-selective fading channel. For FDE, accurate estimation of the channel transfer function is required. In this paper, we propose a pilot-assisted iterative channel estimation that uses a pilot which is time-multiplexed within each chip block for fast Fourier transform (FFT). The pilot acts as a cyclic-prefix of FFT block as well. The achievable BER performance is evaluated by computer simulation.
1Â citations
Cites methods from "Frequency domain equalization for s..."
...Pilot-assisted Channel Estimation for Frequencydomain Equalization of DSSS Signals Koichi Ishihara, Kazuaki Takeda and Fumiyuki Adachi Dept. of Electrical and Communications Engineering, Graduate School of Engineering Tohoku University, Sendai, Japan ishihara@mobile.ecei.tohoku.ac.jp Abstract—...
[...]
...At the receiver, the received spread signal is decomposed into Nc frequency components by applying Nc-point FFT and one-tap FDE is applied to each frequency component as in OFDM or MCCDMA....
[...]
03 Mar 2011
TL;DR: Simulation results show that the bit error rate performance of the proposed method is superior to the FD-LE and the conventional DFE, particularly at low signal to noise power ratio.
Abstract: In this paper, we propose an optimum decision feedback equalizer (DFE) scheme for single carrier frequency division multiple access (SC-FDMA) systems. The scheme is composed of a frequency domain linear equalizer (FD-LE) and a time domain DFE which is made up of a feedforward filter and a feedback filter. The feedforward linear filter is a noise whitening filter (NWF) which whitens the spectrum of the noise colored by the FD-LE. Since the spectrum of the noise is white at the input of the decision device, decision is optimum. Simulation results show that the bit error rate performance of the proposed method is superior to the FD-LE and the conventional DFE, particularly at low signal to noise power ratio.
1Â citations
TL;DR: Low complexity joint equalization and interference compensation (JEIC) schemes are proposed for the DCT-OFDM system with FFD decomposition utilizing the banded implementation of joint ICI matrix after DFRFT at the receiver.
1Â citations
01 Aug 2013
TL;DR: Computer simulations have shown that the proposed scheme is effective in mitigating the combined effects of I/Q imbalance and multipath fading for QPSK and 16-QAM modulation.
Abstract: It is well known that dual-branch receivers suffer from in-phase (I) and quadrature (Q) imbalance problems resulting in distortion and poor signal quality. This paper presents a novel technique, incorporating adaptive estimation and compensation, to mitigate the combined effects of I/Q imbalance and multipath channel on the received signal. Estimation of the channel and I/Q imbalance parameters is performed in time domain using a training sequence. Based on the estimated I/Q imbalance and channel parameters, signal compensation are performed in the frequency domain. Computer simulations have shown that the proposed scheme is effective in mitigating the combined effects of I/Q imbalance and multipath fading for QPSK and 16-QAM modulation. The Symbol Error Rate (SER) achieved for the compensated 16-QAM signal is 10-4, at an SNR of 20dB, which is the same for ideal 16-QAM signal, at an SNR of 19dB.
1Â 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]....
[...]
...Overlap-save or overlap-add signal processing techniques could also be used to avoid the extra overhead of the cyclic prefix [Fer85], [Hay96]....
[...]
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 ]....
[...]
...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 ]....
[...]
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