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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15 Oct 2007
TL;DR: Simulation results show that the proposed technique significantly outperforms the conventional frequency domain equalization by exploiting the frequency domain correlation of noise samples.
Abstract: The use of oversampling at the receiver results in colored noise when the bandwidth of the noise-limiting filter is not sufficiently large. This paper proposes a fractionally-spaced single-carrier linear MMSE frequency domain equalizer (LMMSE-FDE) over frequency-selective multiple input multiple output (MIMO) channels. The performance of the fractionally-spaced LMMSE-FDE with colored noise samples is analyzed and the relation between the time domain correlation and the frequency domain correlation of noise samples is presented. Simulation results show that the proposed technique significantly outperforms the conventional frequency domain equalization by exploiting the frequency domain correlation of noise samples.
11 citations
Cites background from "Frequency domain equalization for s..."
...INTRODUCTION Single-carrier frequency domain equalization (SC-FDE) has been shown to be an effective solution for broadband wireless channels characterized by long impulse response memory [1-3]....
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11 May 2009
TL;DR: In this paper, a low-complexity frequency domain turbo equalization (FDTE) based on linear minimum mean square error (LMMSE) criterion for single-carrier (SC) multiple-input multiple-output (MIMO) underwater acoustic communications (UAC) is proposed.
Abstract: This paper investigates a low-complexity frequencydomain turbo equalization (FDTE) based on linear minimum mean square error (LMMSE) criterion for single-carrier (SC) multiple-input multiple-output (MIMO) underwater acoustic communications (UAC). The receiver incorporates both the equalizer and the decoder which exchange the extrinsic information on the coded bits for each other to implement the iterative detection. The channel impulse responses (CIRs) required in the equalization are estimated in the frequency domain (FD) by inserting the well-designed pilot blocks which are frequency-orthogonal Chu sequences. The proposed SC-MIMO-FDTE architecture is applied to the fixed-to-fixed underwater data gathered during SPACE08 ocean experiments in October 2008, where multiple transducers and hydrophones are deployed in communication ranges of 200m and 1000m, and the channel bandwidth is 9.765625 kHz. The phase shift keying (PSK) signals are transmitted from multiple transducers in various block sizes. The proposed transceiver has been demonstrated to improve the bit-error-rate (BER) performance significantly by processing the QPSK data blocks with block length of 1024 in 200m and 1000m ranges. The average BERs obtained by turbo detection with 3 iterations can achieve approximately 1.4 × 10−4 for the 200m system and 4.4 × 10−5 for the 1000m system.
11 citations
TL;DR: This paper analytically obtain the symbol error rate (SER) of an SC-FDMA system impaired by time or frequency offsets when data is transmitted over a frequency selective Rayleigh fading channel and shows that the proposed analysis can accurately evaluate the SER performance of SC- FDMA systems in the presence of time and frequency uncertainties.
Abstract: In this paper, we consider a single carrier frequency division multiple access (SC-FDMA) system impaired by frequency instabilities and timing offset. In this system, both time and frequency offsets deteriorate the orthogonality of sub-carriers and generate multi-user interference which degrades the system performance. For fast and efficient design of such systems, it is crucial to have an analytical and accurate evaluation of the system performance. However, such closed-form expression for the error rate is available only for perfectly synchronized SC-FDMA systems in the literature. In fact, the performance of SC-FDMA systems in the presence of time or frequency offsets has only been evaluated based on simulations. In this paper, we analytically obtain the symbol error rate (SER) of an SC-FDMA system impaired by time or frequency offsets when data is transmitted over a frequency selective Rayleigh fading channel. Through comparative simulations, we show that our proposed analysis can accurately evaluate the SER performance of SC-FDMA systems in the presence of time and frequency uncertainties.
11 citations
Cites methods from "Frequency domain equalization for s..."
...Since OFDMA system is limited by high peak to average power ratio (PAPR) of transmitted signals which is not an issue in the base stations, this method is utilized in downlink transmission [3]–[7]....
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01 Jan 2003
TL;DR: The proposed error-adjustment scheme for semiblind channel estimation consists of a two-step iteration to achieve even better performance and offers good estimation behavior for MIMO systems.
Abstract: Multiple input multiple output (MIMO) systems have received considerable interest over the last decade because of high system capacity In this paper, we propose an error-adjustment scheme for semiblind channel estimation The algorithm consists of a two-step iteration to achieve even better performance The initial channel estimates are computed using a variant of cyclic prefix (CP): the know symbol padding only technique Then the estimate error of the received symbol is used to adjust the initial channel estimates Computer simulations show that the proposed algorithm offers good estimation behavior for MIMO systems
11 citations
TL;DR: An iterative block (IB) decision feedback equalization (DFE) algorithm is proposed for the intensity-modulation and direct-detection based OCDM system to effectively mitigate the chromatic-dispersion (CD) induced power fading in the fiber.
Abstract: Orthogonal chirp-division multiplexing (OCDM) has recently been proposed as an attractive modulation technique for high-speed fiber-optic systems in virtue of its resilience against system impairments. In this paper, we propose an iterative block (IB) decision feedback equalization (DFE) algorithm for the intensity-modulation and direct-detection (IM/DD) based OCDM system to effectively mitigate the chromatic-dispersion (CD) induced power fading in the fiber. An efficient algorithm is derived to simplify the IB-DFE at the receiver. Analysis is provided to show that the fading effect is compensated by recovering the noisy signals in the vicinity of frequency notches. Simulations were carried out to study the performance of the proposed system. The results show that the proposed system with IB-DFE is able to compensate severe fading effects and improves the bit error rate (BER) by several orders of magnitude. An experiment was implemented to realize 30.3-Gb/s IM/DD-OCDM signal over 50-km fiber, in which power fading due to CD over 20 dB was observed. The experiment results show that the proposed system further reduced the required optical signal-to-noise ratio by 8 dB to achieve a BER of 3 × 10−5.
11 citations
Cites methods from "Frequency domain equalization for s..."
...In order to compensate the CD-induced power fading effect, in this paper, the IB-DFE algorithm [19]–[21] is proposed for the IM/DD-OCDM system....
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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