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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TL;DR: Simulation results show that the BER performance of the proposed scheme is better than QOSTBC for four transmit antennas, and isbetter than OSTBC (orthogonal space-time block code) in the low SNR regime.
Abstract: Conventional space-time block codes are normally designed and studied for Rayleigh flat fading channels. As Single Carrier Frequency-Domain Equalization (SC-FDE) can help to combat the Inter-Symbol Interference (ISI) caused by multipath radio channels, this paper investigates quasi- orthogonal space-time block code (QOSTBC) with Givens rotation in order to enhance the reliability of the SC-FDE transmission in the frequency selective fading channels. To use QOSTBC with Givens rotation for the SC-FDE system, the encoding is performed on the data block basis, and we derive the corresponding decoding method performing in the frequency domain at the receiver. With Givens rotation, the correlation of channel equivalent matrix is eliminated, and the decoding can be performed with linear combiner at the receiver. Such a proposed scheme can achieve full rate transmission and provide high diversity gain. Simulation results show that the BER performance of the proposed scheme is better than QOSTBC for four transmit antennas, and is better than OSTBC (orthogonal space-time block code) in the low SNR regime. 1
2 citations
Cites methods from "Frequency domain equalization for s..."
...Compared with OFDM, the transmission scheme of SC-FDE has the advantages of lower PAPR and less sensitivity to frequency offset [1]....
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24 Oct 2008
TL;DR: An expression for the received signal-to-interference plus noise power ratio (SINR) for a DS-CDMA wireless packet access using FDE and random TPC is derived and the throughput performance is evaluated by numerical computation to discuss the IPI suppression effect of FDE.
Abstract: Recently, we proposed a random transmit power control (TPC) to increase the uplink capacity of DS-CDMA wireless packet access using Rake combining. Furthermore, we evaluated the combined effect of random TPC and inter-path interference (IPI) cancellation and showed that a significant throughput improvement can be achieved if the IPI is sufficiently suppressed. Frequency-domain equalization (FDE) is a promising technique to suppress the IPI. In this paper, we derive an expression for the received signal-to-interference plus noise power ratio (SINR) for a DS-CDMA wireless packet access using FDE and random TPC. Using the derived SINR expression, we evaluate its throughput performance by numerical computation. We compare the throughput using Rake combining with that using FDE to discuss the IPI suppression effect of FDE. It is shown that the throughput using MMSE-FDE approaches that achievable using rake combining w/perfect IC.
2 citations
Cites methods from "Frequency domain equalization for s..."
...We have shown that a combined use of IPI canceller and random TPC provides a significant improvement in the throughput of DS-CDMA slotted ALOHA [6]....
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01 Dec 2013
TL;DR: Simulation results show that in frequency selective fading channels, the proposed scheme can obtain dramatic performance gain compared to the minimum mean square error (MMSE) single carrier frequency domain equalization(FDE) with low complexity.
Abstract: The frequency selective fading channels cause severe inter-symbol interference (ISI) and significantly degrade the bit error rate (BER) performance of broadband wireless communication systems. In this paper, a soft detection algorithm employing the idea of QR decomposition, data grouping and successive interference cancelation (SIC) is proposed for coded single carrier (SC) block transmission. We show that SC block transmission with unique word (UW) brings two unique features while employing the QRD detection method. We refer to them as the natural ordering property and the sparse property, respectively. The data block is divided into small groups and the log-likelihood ratio (LLR) of each element is derived from the bottom up. A flexible tradeoff between BER performance and detection complexity can be provided. Simulation results show that in frequency selective fading channels, the proposed scheme can obtain dramatic performance gain compared to the minimum mean square error (MMSE) single carrier frequency domain equalization(FDE) with low complexity.
2 citations
Cites background from "Frequency domain equalization for s..."
...Thus we can conclude that in frequency selective fading channels, using K = 3 or K = 4 can be enough to guarantee a much better performance than MMSE SC-FDE....
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...In order to combat the inter-symbol interference (ISI), single carrier block transmission with frequency domain equalization (SC-FDE) [2], where data is transmitted block by block in the time domain while equalization is carried out in the frequency domain, is an attractive technique....
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...However, in severe frequency selective fading channels, the noise enhancement problem significantly degrades the BER performance of SC-FDE....
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...Compared to MMSE SC-FDE, the performance gain for K = 3 is more than 4dB at BER=10−5....
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...We also compare the BER performance with that of MMSE SC-FDE....
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Journal Article•
TL;DR: GOFDM 受信では,従来の K 倍の長さの FFT 窓を用いて GOFDM 信号を周波数領 域等化した上で,OFDM 復調する.
Abstract: あらまし OFDM は高速データ信号を多数の直交サブキャリアを用いて並列伝送する.遅延パスの影響を取り除く ため,ガードインターバル(GI)を付加する.しかし,GI を超える長遅延パスが存在すると,サブキャリア間干 渉(ICI)とシンボル間干渉(ISI)が発生し,OFDM 伝送特性が著しく劣化してしまう.そこで,本論文では,GI 付加前の OFDMシンボルを K個まとめて,K倍の長さの GIを付加する一般化 OFDM(GOFDM)を用いることを 提案している.GOFDM 受信では,従来の K 倍の長さの FFT 窓を用いて GOFDM 信号を周波数変換して周波数領 域等化した上で,OFDM 復調する.このような GOFDM では,従来の K 倍のパス遅延まで許容することができる. 本論文では,計算機シミュレーションにより,超遅延パスの存在下での GOFDM 伝送のビット誤り率特性を求め, 従来の OFDM伝送より優れた BER特性が得られることを明らかにしている. キーワード OFDM,周波数領域等化,周波数選択性フェージング.
2 citations
Cites methods from "Frequency domain equalization for s..."
...We use the FDE based on minimum mean square error (MMSE) criterion as used in single-carrier transmission [12], in multicarrier CDMA (MC-CDMA) [13]-[15], and recently in DS-CDMA [16], [17]....
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DOI•
01 Jan 2008
TL;DR: In this article, a low-cost 60 GHz transceiver for Gb/s transmission over short distances (a few meters) is presented, which is intended to support the design of lowcost 60-GHz transceivers for high-definition streaming video and high-speed download.
Abstract: The world-wide availability of the huge amount of license-free spectral space in the 60 GHz band provides wide room for gigabit-per-second (Gb/s) wireless applications. A commercial (read: low-cost) 60-GHz transceiver will, however, provide limited system performance due to the stringent link budget and the substantial RF imperfections. The work presented in this thesis is intended to support the design of low-cost 60-GHz transceivers for Gb/s transmission over short distances (a few meters). Typical applications are the transfer of high-definition streaming video and high-speed download. The presented work comprises research into the characteristics of typical 60-GHz channels, the evaluation of the transmission quality as well as the development of suitable baseband algorithms. This can be summarized as follows. In the first part, the characteristics of the wave propagation at 60 GHz are charted out by means of channel measurements and ray-tracing simulations for both narrow-beam and omni-directional configurations. Both line-of-sight (LOS) and non-line-of-sight (NLOS) are considered. This study reveals that antennas that produce a narrow beam can be used to boost the received power by tens of dBs when compared with omnidirectional configurations. Meanwhile, the time-domain dispersion of the channel is reduced to the order of nanoseconds, which facilitates Gb/s data transmission over 60-GHz channels considerably. Besides the execution of measurements and simulations, the influence of antenna radiation patterns is analyzed theoretically. It is indicated to what extent the signal-to-noise ratio, Rician-K factor and channel dispersion are improved by application of narrow-beam antennas and to what extent these parameters will be influenced by beam pointing errors. From both experimental and analytical work it can be concluded that the problem of the stringent link-budget can be solved effectively by application of beam-steering techniques. The second part treats wideband transmission methods and relevant baseband algorithms. The considered schemes include orthogonal frequency division multiplexing (OFDM), multi-carrier code division multiple access (MC-CDMA) and single carrier with frequency-domain equalization (SC-FDE), which are promising candidates for Gb/s wireless transmission. In particular, the optimal linear equalization in the frei quency domain and associated implementation issues such as synchronization and channel estimation are examined. Bit error rate (BER) expressions are derived to evaluate the transmission performance. Besides the linear equalization techniques, a low-complexity inter-symbol interference cancellation technique is proposed to achieve much better performance of code-spreading systems such as MC-CDMA and SC-FDE. Both theoretical analysis and simulations demonstrate that the proposed scheme offers great advantages as regards both complexity and performance. This makes it particularly suitable for 60-GHz applications in multipath environments. The third part treats the influence of quantization and RF imperfections on the considered transmission methods in the context of 60-GHz radios. First, expressions for the BER are derived and the influence of nonlinear distortions caused by the digital-to-analog converters, analog-to-digital converters and power amplifiers on the BER performance is examined. Next, the BER performance under the influence of phase noise and IQ imbalance is evaluated for the case that digital compensation techniques are applied in the receiver as well as for the case that such techniques are not applied. Finally, a baseline design of a low-cost Gb/s 60-GHz transceiver is presented. It is shown that, by application of beam-steering in combination with SC-FDE without advanced channel coding, a data rate in the order of 2 Gb/s can be achieved over a distance of 10 meters in a typical NLOS indoor scenario.
2 citations
Cites result from "Frequency domain equalization for s..."
...9 dB), but not at higher SNR, which is consistent with the observations in [91]....
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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