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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12 Sep 2022
TL;DR: In this paper , an iterative equalization algorithm is proposed based on various equalization criteria in different iterative steps and shown to improve error performance in equalized symbol decision over Rician multipath channels.
Abstract: Iterative decision-feedback equalization is commonly employed in single-carrier frequency-division-multiplexing to suppress the intersymbol interference (ISI) caused during the equalized symbol decision process while avoiding significant noise enhancement, and thereby provides satisfactory error performance. Conventional algorithms have been designed based on the same equalization criterion in all iterative steps and thus leave the room for performance enhancement in that the reduced levels of residual ISI in ensuing iterative steps are not taken into account. In this paper, an iterative equalization algorithm is proposed based on various equalization criteria in different iterative steps and shown to improve error performance in equalized symbol decision over Rician multipath channels.
1 citations
01 Dec 2003
TL;DR: This work investigates the effect of convolutional coding, interleaving and Viterbi decoding, as they are used for OFDM in the IEEE 802.11a standard, for a single carrier system with frequency domain equalization (SC/FDE).
Abstract: In this work we investigate the effect of convolutional coding, interleaving and Viterbi decoding, as they are used for OFDM (orthogonal frequency division multiplexing) in the IEEE 802.11a standard, for a single carrier system with frequency domain equalization (SC/FDE). We will characterize the effect of decision length (maximal length of the trellis) and code rate in terms of bit error behavior, reliability of soft decisions and implementation effort for the classical Viterbi algorithm as well as for the soft output Viterbi algorithm (SOVA). The (coding) parameters of the simulated system are adapted to the IEEE 802.1 Ia standard for WLAN applications. In detail we will elaborate on the advantages of pilot symbols, that are multiplexed into the data stream as a method to reduce the necessary decision length as well as to reduce the implementation effort and to improve the SOVA output. It will be demonstrated that the use of pilot symbols shows significant advantages that dominate the disadvantages.
1 citations
01 Mar 2007
TL;DR: This paper presents a unified approach to blind channel estimation and interference suppression for block transmission using ZP or CP in both single-carrier (SC) and multicarrier (MC) systems, using a generalized multichannel minimum variance principle to design an equalizing filterbank.
Abstract: Block transmission has recently been considered as an alternative to the conventional continuous transmission technique. In particular, block transmission techniques with zero padding (ZP) and cyclic prefix (CP) are becoming attractive procedures for their ability to eliminate both inter-symbol interference (ISI) and inter-block interference (IBI). In this paper, we present a unified approach to blind channel estimation and interference suppression for block transmission using ZP or CP in both single-carrier (SC) and multicarrier (MC) systems. Our approach uses a generalized multichannel minimum variance principle to design an equalizing filterbank. Channel estimate is then obtained from an asymptotically tight lower bound of the filterbank output power. Numerical examples show that the proposed schemes approach the CRB as the signal-to-noise ratio (SNR) increases. Additionally, they exhibit low sensitivity to unknown narrowband interference and compare favorably with subspace blind channel estimators.
1 citations
Additional excerpts
...It was shown in [6] that block SC transmission, has similar equalization complexity and coded performance to that of OFDM....
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TL;DR: This work considers the uplink of BS cooperation schemes employing SC-FDE modulations and a detection performed through receivers based on the IB-DFE (Iterative Block Decision Feedback Equalization) concept, and presents accurate approaches for obtaining the spectral characterization of the quantization noise.
1 citations
Cites background from "Frequency domain equalization for s..."
...OFDM signals are much higher than the envelope of single-carrier signals with the same constellations, indicating that OFDM is clearly preferable for the downlink while SC-FDE is more suitable for the uplink transmission [8], [9]....
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01 Jan 2011
TL;DR: The 3GPP (3rd Generation Partnership Project) as mentioned in this paper ) is a project that aims to develop a 3G network for long-term evolution (LTE) technologies.
Abstract: 近年，スマートフォンのような高機能端末が一般層へ普及してきたことを起爆剤として，動画配信等のブロードバンドサービスを中心に無線ネットワークにおけるデータトラヒックが爆発的に増大している．本稿では，そのような背景の下，10年後の未来に向けて飛躍的な無線ネットワークの大容量化を実現する次世代の無線アクセス (将来無線アクセス) の要求条件を示すとともに，それを達成するための技術課題について，3GPP (3rd Generation Partnership Project) で標準化が行われているLTE (Long Term Evolution) 及びLTE-Advancedの技術動向を考慮しつつ考察する．
1 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