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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27 Feb 2008
TL;DR: CDTD, FDE, DS-CDMA,周波数領域等化(FDE) ers, の直接拡散符号分割マルチアクセス(DS- CDMA) の伝送特性を改 善する技術として,
Abstract: あらまし 周波数選択性フェージング環境下での直接拡散符号分割マルチアクセス(DS-CDMA)の伝送特性を改 善する技術として,平均二乗誤差最小(MMSE)規範に基づく周波数領域等化(FDE)を用いる循環遅延送信ダイバーシ チ(CDTD)が知られている.CDTD は,アンテナ毎に異なる循環遅延を与えて同じデータシンボルを複数アンテナか ら同時送信する送信ダイバーシチ技術で,等価的にパス数を増加させることができるため,大きな周波数ダイバー シチ効果が得られる.MMSE-FDE の後に時間領域逆拡散を行う従来の信号検出法では,等化後に発生する残留チッ プ間干渉(ICI)がビット誤り率(BER)特性の改善に限界を与えている.そこで,本論文では,等化と逆拡散を周波数 領域で同時に行う FDEを提案し,そのときの平均BER特性を計算機シミュレーションによって明らかにしている. キーワード DS-CDMA,循環遅延送信ダイバーシチ(CDTD),周波数領域等化(FDE)
1 citations
01 Nov 2014
TL;DR: An adaptive frequency-domain (spectrum) puncturing method for turbo coded single-carrier transmission that adaptively selects the frequency components to be punctured for frequency efficiency enhancement assuming channel knowledge at the transmitter.
Abstract: This paper proposes an adaptive frequency-domain (spectrum) puncturing method for turbo coded single-carrier transmission. The proposed method is based on previous work on frequency-domain puncturing at the transmitter and turbo equalization at the receiver. While we previously assumed fixed frequency-component puncturing, the newly proposed method adaptively selects the frequency components to be punctured for frequency efficiency enhancement assuming channel knowledge at the transmitter. By selecting frequency components whose channel gains are relatively low for puncturing, the inter-symbol interference due to the frequency-domain channel variation caused by the frequency-selective fading is reduced and the received signal power is increased. As a result, the proposed adaptive frequency-domain puncturing method enhances the error rate at the receiver. Simulation results show the improvement in the error rate by using the proposed method compared to the conventional method.
1 citations
Cites background or methods from "Frequency domain equalization for s..."
...DFT-Spread OFDM allows us to change flexibly the transmission bandwidth and frequency, which accommodates frequencydomain channel-dependent scheduling....
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...Therefore, we applied frequency-domain turbo equalization [2, 7-9] at the receiver to mitigate the ISI....
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...One example is discrete Fourier transform (DFT)-spread orthogonal frequency division multiplexing (OFDM) [1-3], which generates a singlecarrier transmission signal in the frequency domain that has many commonalities to OFDM signal generation....
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...Assuming that the CP is appended to each DFT block [2, 3] and the length of the CP is sufficiently long so that it covers the entire multipath delay spread, the N × N-dimensional channel matrix, Hl, at the l-th receiver antenna (l = 1, ....
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...Thanks to the use of a cyclic prefix (CP) similar to the pure OFDM signal, computationally-efficient frequency-domain channel equalization [1, 2] is possible with DFT-Spread OFDM, which results in a significant performance improvement in a frequency-selective fading channel....
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03 Dec 2010
TL;DR: This paper has verified that the MLD with ZP exhibits the better BER characteristics than the conventional FDE with CP and decreased the computational complexity of MLD using M algorithm.
Abstract: In this paper, we have proposed the signal separation and equalization schemes for MFSK signals using FDE (Frequency Domain equalization) with CP (Cyclic Prefix) and the MLD (Maximum Likelihood Detection) with ZP (Zero Padding) on quasi-static MIMO frequency selective channels. Through computer simulations, we have verified that the MLD with ZP exhibits the better BER characteristics than the conventional FDE with CP [1]-[3]. Moreover, we have decreased the computational complexity of MLD using M algorithm.
1 citations
Cites methods from "Frequency domain equalization for s..."
...We have already shown that the FDE scheme using CP [4] is also applicable to the equalization of FSK signals [1]-[3] where the equalization is dome before the demodulation process of FSK [5], which includes nonlinear signal processing....
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01 Dec 2006
TL;DR: Simulations show that the proposed method performs close to the equalizers with perfect channel knowledge at the receiver, followed by a method which solves permutation problem.
Abstract: This paper considers an UWB (Ultra-wideband) SC-FDE (single-carrier input-multiple output with frequency domain equalization) system for multiuser The method exploits higher order statistics (HOS) in the received signals It is followed by a method which solves permutation problem The permutation problem is caused by the Fourier transform (FFT) operations Simulations show that the proposed method performs close to the equalizers with perfect channel knowledge at the receiver
1 citations
25 Nov 2013
TL;DR: An implementation of frequency domain equalizer (FDE) in the multimode receiver on an application specific integrated circuit (ASIC) that is useful to demodulate signals with different air interfaces while optimally selecting an appropriate air interface in the heterogeneous wireless system.
Abstract: Heterogeneous wireless systems such as a combination of mobile broadband wireless access (MBWA) and wireless local area network (WLAN) are candidates to attain higher throughput and wide coverage in the next generation mobile communication systems. A multimode receiver to demodulate signals with multiple air interfaces is required in the heterogeneous systems. In this paper, we discuss an implementation of frequency domain equalizer (FDE) in the multimode receiver on an application specific integrated circuit (ASIC). The proposed multimode FDE could realize adaptively demodulate two systems (single carrier and multi carrier) depending on propagation environment. A multimode FDE ASIC is designed and implemented on 180-nm complementary metal-oxide semiconductor (CMOS). Core size of multimode FDE chip is 17.6 mm2. The experimental results show that the ASIC yields a throughput of 48.1 Mbit/s at a sampling rate of 100 MHz. The results also show that the power penalty of the measured bit error rate (BER) performance is only 1 dB at a BER of 10-3 in a 4-paths Rayleigh fading channel. We consider that the implemented ASIC is useful to demodulate signals with different air interfaces while optimally selecting an appropriate air interface in the heterogeneous wireless system.
1 citations
Cites background from "Frequency domain equalization for s..."
...In [1], [2], the effect of single carrier (SC) FDE is shown by the computer simulation....
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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]....
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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