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Journal ArticleDOI

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.

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Citations
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Proceedings ArticleDOI
22 Apr 2008
TL;DR: In this paper, a FPGA implementation of single carrier (SC) wireless system with frequency domain equalization (FDE) to overcome the effects of multipath fading channels is presented.
Abstract: In this paper, we present a FPGA implementation of single carrier (SC) wireless system with frequency domain equalization (FDE) to overcome the effects of multipath fading channels. We propose a new packet format for this wireless system to reduce the error of channel estimation that occurs in the last part of the packet caused by time fluctuation of the channel. Our targets are veracity 15 km/h and 3 Mbps data rate under 1 MHz bandwidth. Simulation results show that our proposed system can work in severe multipath fading with 33 Hz Doppler shift (15 km/h) and 6 ppm frequency offset environment. The logic synthesis result meets the specification.
01 Jan 2006

Cites background from "Frequency domain equalization for s..."

  • ...Das in OFDM angewendete Prinzip der Frequenzbereichsentzerrung kann auch für die Einträgermodulation genutzt werden [18]....

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11 Dec 2013
TL;DR: It is confirmed that STBC-JTRD and MSE will not be competing for the CDP-CE contract.
Abstract: あらまし これまでに我々は,シングルキャリア(SC)周波数領域時空間符号化送受信ダイバーシチ (FD-STBC-JTRD)を対象に,1 符号語を構成する複数の符号ブロックの一つ一つに対応して複数の重みを用いる マルチブロックFDEを提案し,1符号語内で共通のFDE重みを用いる従来のFDEより優れた平均ビット誤り率(BER) 特性を達成できることを明らかにした.しかしながら,FD-STBC-JTRD におけるマルチブロック送信 FDE に関する これまでの検討では準静的フェージングを仮定しており,1 符号語内におけるチャネルの時間変動を考慮していな かった.そこで本稿では,SC 時分割複信(TDD)を対象に 1 符号語内におけるチャネルの時間変動を考慮した上 で,STBC 符号化前の送信信号を STBC 復号後の受信信号との平均二乗誤差(MSE)を最小とするように上りリン クマルチブロック受信 FDE 重みおよび下りリンクマルチブロック送信 FDE 重みを決定する.計算機シミュレーシ ョンにより,チャネル情報が理想的に得られる場合は,マルチブロック FDE を用いることによって,1 符号語内の チャネルの時間変動を考慮しない FDE を用いる場合より,常に優れた平均 BER 特性が得られることを明らかにし ている.また循環遅延パイロットチャネル推定(CDP-CE)および最小二乗法による予測を用いた場合の平均 BER 特性を明らかにし,チャネル推定の時間追従性がマルチブロック FDE に及ぼす影響について考察している. キーワード 時空間符号化,周波数領域等化,高速フェージング

Additional excerpts

  • ...まず周波数選択性フェージングを克服する技術と して,最小平均二乗誤差(MMSE)規範に基づく周波 数領域等化(FDE)が広く知られている [3,4]....

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20 Feb 2013
TL;DR: TS-SC 伝送では, ブロック毎に挿入されている TS を利用してチャネル推定に関する検討を行っていた; TS-SC-RLS-CEは、従来の限界があった.
Abstract: あらまし 本稿では,既知のトレーニング系列(TS)を周期的に挿入したシングルキャリアブロック伝送(TS-SC 伝 送)における周波数領域等化(FDE)のための周波数領域チャネル推定に関する検討を行っている.TS-SC 伝送では, ブロック毎に挿入されている TS を利用してチャネル推定を行うことができるから,チャネル推定のためにパイロ ットブロックを送信する必要がない.これまで筆者らは,TS-SC 伝送を対象に単純平均型繰り返しチャネル推定 (SA-CE)および RLS アルゴリズムに基づくチャネル推定(RLS-CE)を提案した.SA-CE は低速フェージング環境下に おいてチャネル推定精度を向上し,理想チャネル推定の場合に近い優れたビット誤り率(BER)特性を達成できるこ と,また,RLS-CE はフェージング変動が速い場合に,SA-CE よりも優れた BER 特性を実現できることを示してき た.しかし,従来の RLS-CE はフェージング変動への追従能力に限界があった.本稿では,フェージング追従能力 を更に向上するために最小 2 乗法による予測を導入した RLS-CE を提案し,2 重(時間および周波数)選択性フェージ ングチャネルにおける平均 BER 特性を計算機シミュレーションにより明らかにしている. キーワード シングルキャリア,周波数領域等化,既知系列,チャネル推定,RLS アルゴリズム,予測

Additional excerpts

  • ...まえがき 広帯域移動無線チャネルは,遅延時間の異なる複数 の伝搬路から構成される周波数選択性フェージングチ ャネルであるため,シングルキャリア (SC)伝送では, 厳しい符号間干渉が発生し伝送特性が大幅に劣化して しまう [1].最小平均二乗誤差 (MMSE)規範に基づく周 波数領域等化 (FDE)を用いれば,周波数ダイバーシチ 効果が得られるので厳しい周波数選択性フェージング 環境下においても優れた伝送特性を実現できる [2-4]. FDE は,離散フーリエ変換 (DFT)を用いて受信信号 を直交周波数分解して周波数領域で等化を行うブロッ ク信号処理である.DFT…...

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Proceedings ArticleDOI
01 Jan 2016
TL;DR: Simulation results suggest that SC-FrFDE is suitable for underwater acoustic channels with frequency selective fading, and the aim of eliminating ISI and meanwhile minimizing mean-square error caused by noise, without introducing the high computational complexity caused by complex technologies such as decision feedback.
Abstract: Single carrier frequency domain equalization (SC-FDE) is an important means of high data rate communication. Considering frequency selective fading in the underwater acoustic channel, there are some disadvantages with respect to the traditional SC-FDE. When using Frequency Domain Linear Equalization (FD-LE), the equalizer based on zero-forcing rules may magnify noise at deep fading points of frequency domain, while the equalizer based on the least mean-square error rule cannot completely eliminate Inter-Symbol Interference (ISI). Frequency domain decision feedback equalization (FD-DFE) and frequency domain equalization noise prediction (FDE-NP) can make up this insufficiency, but the computational complexity of these methods is greater. With the aim of eliminating ISI and meanwhile minimizing mean-square error caused by noise, but without introducing the high computational complexity caused by complex technologies such as decision feedback, we propose a single carrier fractional Fourier domain equalization (SC-FrFDE) technique. With this technique, the channel response and equalizer coefficients in optimal-order fractional Fourier domain (FrFD) are calculated, turning the equalization to an FrFD with flat fading. In the simulation experiment, two underwater acoustic channels — the channel of a laboratory pool and Quangang Harbour — are chosen in order to test the performance of SC-FDE and SC-FrFDE, with reference to correlation, convergence and bit error rate. The simulation results demonstrate that both of these two methods have nearly the same effects when signals transmitted through the channel of a laboratory pool, while the performance of SC-FrFDE has significant improvement gains over traditional SC-FDE in the channel of Quangang Harbour, whose frequency selective fading is much more serious than the latter. The simulation results suggest that SC-FrFDE is suitable for underwater acoustic channels with frequency selective fading.
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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Journal ArticleDOI
Jr. L.J. Cimini1
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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Book
Simon Haykin1
01 Mar 1991

2,447 citations

Journal ArticleDOI
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

Journal ArticleDOI
D. Chu1
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