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
TL;DR: This work considers a reconfigurable receiver architecture building on concepts from time-frequency (TF) signal analysis, which includes TF signal representations in form of a Gabor expansion along with a compatible parameterization of time-variant channels.
Abstract: There is a trend towards flexible radios which are able to cope with a range of wireless communication standards. For the integrated processing of widely different signals—including single-carrier, multicarrier, and spread-spectrum signals—monolithic baseband receivers need universal formats for the signal representation and channel description. We consider a reconfigurable receiver architecture building on concepts from time-frequency (TF) signal analysis. The core elements are TF signal representations in form of a Gabor expansion along with a compatible parameterization of time-variant channels. While applicable to arbitrary signal types, the TF channel parameterization offers similar advantages as the frequency domain channel description employed by orthogonal frequency-division multiplexing receivers. The freedom in the choice of the underlying analysis window function and the scalability in time and frequency facilitate the handling of diverse signal types as well as the adaptation to radio channels with different delay and Doppler spreads. Optimized window shapes limit the inherent model error, as demonstrated using the example of direct-sequence spread-spectrum signaling.
1 citations
Cites background from "Frequency domain equalization for s..."
...Optimized window shapes limit the inherent model error, as demonstrated using the example of direct-sequence spread-spectrum signaling. key words: reconfigurable radio, doubly dispersive channel, timefrequency analysis, Gabor expansion, waveform design...
[...]
Dissertation•
01 Mar 2019
TL;DR: This work analyses receivers that can handle the downsides of channel equalization algorithms and demonstrates that the SVD receiver can be appealing as a solution for Physical Layer Security (PLS) in mMIMO systems.
Abstract: As the demands for faster and cheaper telecommunication systems continue to grow, so to do the demands for more efficient and secure systems. There have been several solutions proposed, with the most commonly accepted ones employing Massive Multiple Input, Multiple Output (mMIMO), featuring large arrays of antennas. The downside of these systems lies mainly in the need for computationally heavy channel equalization algorithms and the high hardware requirements, namely due to the need of many Power Amplifiers (PAs), Analog-to-Digital Converters (ADCs) and Digital-to-Analog Converters (DACs). This work analyses receivers that can handle these downsides, beginning with the low complexity equalization receivers Maximal-Ratio Detector (MRD) and Equal-Gain Detector (EGD), that can lower the equalization’s computation time. Then a Singular Value Decomposition (SVD) receiver is studied, with a proposed interleaving scheme to allow for equal performance on all streams, combined with a scheme for estimating and cancelling the non-linear distortion to reduce the impact of cheaper and more powerefficient PAs. These receivers are then improved with the introduction of an error correcting convolutional code. Lastly, it is demonstrated that the SVD receiver can be appealing as a solution for Physical Layer Security (PLS) in mMIMO systems.
1 citations
Cites methods from "Frequency domain equalization for s..."
...To mitigate this problem we employ FDE, seen in [6]....
[...]
TL;DR: A single-carrier transmission/reception system to which an alternate time-switched space-time block coding technique is applied, includes a bit input unit, a symbol mapping unit, and a guard-period inputting unit for putting a guard period into a data block.
Abstract: The present invention relates to a single-carrier transmission/reception system to which an alternate time-switched space-time block coding technique is applied, and a method thereof. According to the present invention, a single-carrier transmission/reception system, to which an alternate time-switched space-time block coding technique is applied, includes a bit input unit, a symbol mapping unit, a guard-period inputting unit for putting a guard period into a data block, a D/A converting unit, a first wireless signal converting unit, a switch for alternately switching a wireless signal, a transmitter including a plurality of transmission antennas to transmit the wireless signal corresponding to the alternate switching, a reception antenna for receiving a wireless signal of the data block having the guard period, a second wireless signal converting unit, an A/D converting unit, a lapping-around addition unit, a fast Fourier transform (FFT) unit, a channel prediction unit, a maximum rate reception combination unit for receiving the predicted channel and a frequency region signal to perform a maximum rate reception combination according to the predicted channel, an inverse fast Fourier transform (IFFT) unit, and a receiver including a data determination unit.
1 citations
19 Apr 2010
TL;DR: A soft information calculation method for SC-FDE output symbol is proposed which increases the accuracy of information into the SISO decoder of Shannon limit codes and improves the transmission system.
Abstract: The hard decision symbol of conventional SC-FDE output is not perfect to the posterior SISO decoder of Shannon limit codes such as Turbo code and LDPC codes, which can achieve the Shannon limit performance on condition that the in-out information is soft. In this paper, a soft information calculation method for SC-FDE output symbol is proposed which increases the accuracy of information into the SISO decoder of Shannon limit codes and improves the transmission system. The numerical simulation results also show that the soft output SC-FDE gains an advantage over the hard one and the additional SNR gain can be obtained in frequency selective channel.
1 citations
Cites background from "Frequency domain equalization for s..."
...Therefore that has lead researchers to consider equalization on frequency domain....
[...]
05 Dec 2005
TL;DR: In this paper, a class of low complexity linear frequency domain precoders (multiple-beamformers) for spatially correlated frequency selective MIMO systems employing single carrier (SC) modulations employing frequency domain equalization (FDE) have been shown to be appropriate for severe time-dispersive channels, having similar or better performances than OFDM modulations, while offering the same complexity and lower peak to average power ratio.
Abstract: Single carrier (SC) modulations employing frequency domain equalization (FDE) have been shown to be appropriate for severe time-dispersive channels, having similar or better performances than OFDM modulations, while offering the same complexity and lower peak-to-average power ratio. In this paper we introduce a class of low complexity linear frequency domain precoders (multiple-beamformers) for spatially correlated frequency selective multiple-input-multiple-output MIMO systems employing SC modulations. The specific designs targets minimization of a lower bound on the mean-square-error (MSE) under the assumption that only second order statistics of channel (covariance matrix of channel and noise) is available at the transmitter. These precoders are designed for different wideband receivers such as BLAST, MIMO-DFE, linear FDE. The proposed designs are assessed and compared for relatively large correlations and severely frequency selective channels.
1 citations
Cites background from "Frequency domain equalization for s..."
...Single carrier modulations (SC) employing Frequency-Domain Equalization (FDE) schemes are another valuable candidate for highly dispersive channels in broadband wireless communications [2]–[4]....
[...]
..., the transmission from the mobile terminals to the base station) [3], [4]....
[...]
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]....
[...]
...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.
2,627 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. >
1,816 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