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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TL;DR: In this paper , the authors investigated the system capacity of dual-polarized orbital angular momentum (OAM) multiplexing that employs single-carrier with frequency domain equalization (FDE) in urban street canyon environments.
Abstract: This study investigates the system capacity of dual-polarized orbital angular momentum (OAM) multiplexing that employs single-carrier with frequency domain equalization (FDE) in urban street canyon environments. To overcome the impact of multipaths, two types of FDE, designed with and without the consideration of the cross-polarization interference (XPI), are introduced. We derive the effects of the residual inter-mode interference (IMI), inter-symbol interference (ISI), and XPI when applying such FDE and incorporate their impacts into the system capacity analysis. Moreover, we adopt the urban street canyon model based on a ray-tracing simulation, which enables performance evaluation in a realistic multipath environment. The numerical results show that although the computational complexity is increased, the consideration of the XPI in the FDE weight design improves the system capacity, and its effectiveness is remarkable in the cases of short link distances.
1 citations
Dissertation•
01 Nov 2014
TL;DR: This work will consider offset modulation signals with quasi-constant envelope and develop receivers that will obtain good BER performance, but these signals require a bandwidth significantly above the Nyquist rate, which can be reduced by an overlap of different frequency channels.
Abstract: Future broadband wireless systems are expected to cope with severely time dispersive channels, due to multi-path signal propagation between the transmitter and the receiver while having high power and spectral efficiency. Thus, advanced Frequency Domain Equalization techniques are required. The implementation complexity in mobile terminals should be as low as possible to achieve highest possible efficiency. Therefore, most of the signal processing requirements will be shifted to the base station and we will employ signals compatible with an efficient, grossly nonlinear power amplification. For this reason, we will consider offset modulation signals with quasi-constant envelope and develop receivers that will obtain good BER performance. However, these signals require a bandwidth significantly above the Nyquist rate, which can be reduced by an overlap of different frequency channels.
1 citations
26 Dec 2006
TL;DR: In this paper, a multiple-input multiple-output (MIMO) system employing single-carrier (SC) transmission with frequency domain pre-and post-processing is presented, where the Dominant Eigenmode Transmission (DET) is deployed as a typical application for such a pre- and post-processed system.
Abstract: In this contribution, we present a Multiple-Input Multiple-Output (MIMO) system employing Single-Carrier (SC) transmission with frequency domain pre- and post-processing to allow a further adaptation of the transmission. The so-called Dominant Eigenmode Transmission (DET), which is based on the Singular Value Decomposition (SVD) algorithm, is deployed as a typical application for such a pre- and post-processed system. Furthermore, the MIMO SC-FDE based and the MIMO OFDM based schemes with and without DET are compared for equal data-rate systems by means of computer simulation, showing a significant performance advantage for MIMO SC-FDE based schemes.
1 citations
Cites background from "Frequency domain equalization for s..."
...frequency offsets and less sensitivity concerning phase noise are advantages, which make SC-FDE based schemes a reasonable alternative to OFDM based schemes [6]....
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...Note that strong channel coding is essential for OFDM to exploit frequency diversity [6], which yields lower efficiency in terms of the net data rate....
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Patent•
01 Mar 2017
TL;DR: An apparatus for quantized linear amplification with nonlinear amplifiers that performs a linear amplification of variable-envelope single carrier (SC) or multi-carrier (MC) bandpass signals, based on sampled and quantized versions of its complex envelope, where the quantizer generates bits that are mapped into Nm≤Nb polar components, in which the quantized symbol can be decomposed, that are modulated as Nm constant or quasi constant envelope signals and where each one is amplified by a nonlinear amplifier.
Abstract: An apparatus for quantized linear amplification with nonlinear amplifiers that performs a linear amplification of variable-envelope single carrier (SC) or multi-carrier (MC) bandpass signals, based on sampled and quantized versions of its complex envelope, where the quantizer generates Nb bits that are mapped into Nm≤Nb polar components, in which the quantized symbol can be decomposed, that are modulated as Nm constant or quasi constant envelope signals and where each one is amplified by a nonlinear amplifier.
1 citations
18 Mar 2008
TL;DR: The obtained results show a large performance improvement when using such an interference cancellation scheme in the receivers relative to the RAKE receiver, and frequency domain equalization (FDE) only.
Abstract: This paper presents four frequency domain interference cancellation receivers for the single-input single-output (SISO) as well as single-input multiple-output (SIMO) downlink CDMA systems. The proposed receivers employ an interference cancellation scheme to suppress the interference caused by the multipath fading channel. All filters in the proposed receivers are implemented in frequency domain. The performance of the suggested receivers is studied and compared to other traditional receiver schemes. The effects of channel estimation, and number of active users on the performance of the proposed schemes are also studied. The obtained results show a large performance improvement when using such an interference cancellation scheme in the receivers relative to the RAKE receiver, and frequency domain equalization (FDE) only.
1 citations
Cites background from "Frequency domain equalization for s..."
...Recently, single carrier block transmission with frequency domain equalization has proved to be a promising candidate for broadband wireless communications, especially when implementation issues such as the power consumption and the system complexity are taken into consideration [1-4]....
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...Conventional equalization in the time domain may become impractical because it requires one or more transversal filters with a tap number covering the maximum channel impulse response length [1]....
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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