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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TL;DR: A blind identification method for MIMO single carrier zero padding block transmission systems using periodic preceding on the source signal before transmission and the design of the precoding sequence to minimize the noise effect in covariance matrix estimation is proposed.
Abstract: We propose a blind identification method for multiple-input multiple-output (MIMO) single-carrier zero-padding block-transmission systems. The method uses periodic precoding on the source signal before transmission. The estimation of the channel impulse response matrix consists of two steps: 1) obtain the channel product matrix by solving a lower-triangular linear system; 2) obtain the channel impulse response matrix by computing the positive eigenvalues and eigenvectors of a Hermitian matrix formed from the channel product matrix. The method is applicable to MIMO channels with more transmitters or more receivers. A sufficient condition for identifiability is simply that the channel impulse response matrix is full column rank. The design of the precoding sequence which minimizes the noise effect in covariance matrix estimation is proposed and the effect of the optimal precoding sequence on channel equalization is discussed. Simulations are used to demonstrate the performance of the method.
28 citations
15 May 2016
TL;DR: An overview and preliminary comparison of several multi-car carrier and single-carrier waveforms that are potential candidates for future 5G mobile radio communications above 6 GHz and a common framework for synthesizing different waveform candidates is developed.
Abstract: This paper provides an overview and preliminary comparison of several multi-carrier and single- carrier waveforms that are potential candidates for future 5G mobile radio communications above 6 GHz. The waveforms are assessed primarily based on the established and known results as well as recent findings keeping in view the design requirements that are relevant to using frequencies above 6 GHz, especially the millimeter wave frequencies. The Key Performance Indicators and degrees of freedom in the design of different waveforms and their potential applications for mm-wave communications are discussed. Certain features that are particularly interesting for mm-wave communication and require further investigations are also highlighted. Furthermore, a common framework for synthesizing different waveform candidates has been developed. Finally, a preliminary qualitative comparison of different multi-carrier and single carrier waveforms has been derived.
28 citations
Cites background from "Frequency domain equalization for s..."
...The total complexity however remains the same as CP-OFDM [28]....
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TL;DR: This work evaluates multicarrier modulation methods for 100 Gb/s single-wavelength data center interconnects using two different orthogonal frequency-division multiplexing techniques: DC-biased OFDM and asymmetrically clipped optical OFDM (ACO-OFDM).
Abstract: We evaluate multicarrier modulation methods for 100 Gb/s single-wavelength data center interconnects. We consider two different orthogonal frequency-division multiplexing (OFDM) techniques: DC-biased OFDM (DC-OFDM) and asymmetrically clipped optical OFDM (ACO-OFDM). We also consider two different techniques for bit loading and power allocation: fixed bit loading with preemphasis and optimized bit loading and power allocation. We first present a semianalytical performance and complexity evaluation of these OFDM methods including the effects of linear filtering, clipping, and quantization. We then include the effects of chromatic dispersion and chirp, as well as intensity and shot noises. Performance is quantified in terms of the required average optical power to achieve a target bit-error probability for a given modulator bandwidth. Complexity is quantified in terms of the resolution and sampling rate required of digital-to-analog (DAC) and analog-to-digital (ADC) converters, as well as the number of signal processing operations required. For each OFDM technique, we adjust the clipping ratio to minimize the optical power requirement. For DC-OFDM, taking into account the DAC frequency response reduces the optical power requirement up to 2 dB. ACO-OFDM is more power efficient and requires lower DAC/ADC resolution than DC-OFDM, but ACO-OFDM requires prohibitively high sampling rates owing to its poor spectral efficiency.
28 citations
Additional excerpts
...Counterpart [28], [29]....
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19 Apr 2015
TL;DR: A probabilistic approach to the LMS filter is introduced, which provides an adaptable step-size LMS algorithm together with a measure of uncertainty about the estimation and preserves the linear complexity of the standard LMS.
Abstract: We introduce a probabilistic approach to the LMS filter. By means of an efficient approximation, this approach provides an adaptable step-size LMS algorithm together with a measure of uncertainty about the estimation. In addition, the proposed approximation preserves the linear complexity of the standard LMS. Numerical results show the improved performance of the algorithm with respect to standard LMS and state-of-the-art algorithms with similar complexity. The goal of this work, therefore, is to open the door to bring somemore Bayesian machine learning techniques to adaptive filtering.
28 citations
Cites background from "Frequency domain equalization for s..."
...This approach is widely understood and applied to several problems such as echo cancellation [4], noise cancellation [5], and channel equalization [6]....
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TL;DR: It is shown that the use of frequency-domain equalization (FDE) based on minimum mean-square error (MMSE) criterion for the reception of multicode DS-CDMA packet gives an improved throughput irrespective of the channel's frequency-selectivity.
Abstract: The next-generation mobile communications system is anticipated to support very high-speed data rates exceeding several tens megabits per second. In this paper, we consider high-speed downlink packet access for direct-sequence code-division multiple access (DS-CDMA) as in third-generation wideband code-division multiple-access systems. Adaptive modulation and coding (AMC), multicode operation and hybrid automatic repeat request (HARQ) will be the enabling technologies. With such high-speed data transmissions, however, multicode operation severely suffers from the loss of orthogonality among the spreading codes since the wireless channel becomes severely frequency-selective. In this paper, we apply frequency-domain equalization (FDE) based on minimum mean-square error (MMSE) criterion instead of conventional rake combining for receiving the packet. A new MMSE-FDE weight is derived for packet combining. The throughput in a frequency-selective Rayleigh-fading channel is evaluated by computer simulation for Chase combining and incremental redundancy (IR) packet combining. It is shown that the use of MMSE-FDE for the reception of multicode DS-CDMA packet gives an improved throughput irrespective of the channel's frequency-selectivity.
28 citations
Cites methods from "Frequency domain equalization for s..."
...A new MMSE-FDE weight is derived for frequency-domain packet combining and the packet throughput is evaluated under full load conditions over a severe frequency-selective channel....
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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