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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Patent•
23 May 2017
TL;DR: In this paper, a transmitter/receiver apparatus and method provide adaptive data rate fading compensation that utilize dual-polarization transmissions at a constant modulation-symbol rate over a forward-scatter radio link and that employ adaptive receiver techniques that operate efficiently at the noisy uncoded signal-to-noise ratio threshold of present-day forward-error correction codes over the range of multipath widths in such forwardscatter environments.
Abstract: A transmitter/receiver apparatus and method provide adaptive data rate fading compensation that utilize dual-polarization transmissions at a constant modulation-symbol rate over a forward-scatter radio link and that employ adaptive receiver techniques that operate efficiently at the noisy uncoded signal-to-noise ratio threshold of present-day forward-error correction codes over the range of multipath widths in such forward-scatter environments. The dual-polarization transmissions support both dual transmission and dual diversity configurations. The adaptive receiver techniques include adaptive channel matched filtering and adaptive equalizing at the modulation-symbol rate.
4 citations
04 Dec 2014
TL;DR: A complexity-reduced per-antenna MAI cancellation before diversity combining is proposed, which is suitable for DAN using DS-CDMA and achieves almost the same uplink capacity as fullMAI cancellation after diversity combining.
Abstract: —DS-CDMA allows all accessing users to share the same carrier frequency and hence, can alleviate the sophisticated channel management problem. Recently, we investigated a distributed antenna network (DAN) using direct-sequence code division multiple access (DS-CDMA) with joint antenna diversity and equalization and showed that DAN achieves higher uplink capacity than centralized antenna network (CAN). The uplink capacity is limited due to multiple access interference (MAI). In this paper, to further improve the uplink capacity, we propose a complexityreduced per-antenna MAI cancellation before diversity combining, which is suitable for DAN using DS-CDMA. In the perantenna MAI cancellation, first, interfering users on each antenna are sorted in descending order of the instantaneous received power. Then, a predetermined number of interfering users having the highest received powers are selected on each antenna to be cancelled in the frequency-domain before diversity combining. It is shown by computer simulation that per-antenna MAI cancellation before diversity combining achieves almost the same uplink capacity as full MAI cancellation after diversity combining.
4 citations
Additional excerpts
...The use of the minimum mean square error (MMSE) based frequency-domain equalization (FDE) achieves a good transmission performance [6-9]....
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11 Dec 2009
TL;DR: It is shown thatSCM employing a frequency domain MMSE equalizer has a better bit error rate (BER) performance than OFDM, and the performance comparison of SCM and OFDM systems in the presence of NBI over additive white gaussian noise (AWGN) link shows that SCM is less sensitive to NBI.
Abstract: Orthogonal Frequency Division Multiplexing (OFDM) has the inherent problem of high peak to average power ratio (PAPR). Moreover, it suffers from high sensitivity to frequency offsets and narrowband interference (NBI). Contrary to this, Single Carrier Modulation (SCM) offers smaller PAPR and reduced sensitivity to NBI. However, it requires an efficient channel equalization technique. In literature, frequency domain channel equalization has been proposed for SCM systems in wireless communications. It also possesses the advantage of lower complexity in signal processing, as in the case of OFDM. This paper presents performance comparison between OFDM and SCM with frequency domain equalization for multipath wireless channel. SCM utilizes minimum mean square error (MMSE) algorithm for the training of the frequency domain equalizer. It is shown that SCM employing a frequency domain MMSE equalizer has a better bit error rate (BER) performance than OFDM. Also, the performance comparison of SCM and OFDM systems in the presence of NBI over additive white gaussian noise (AWGN) link shows that SCM is less sensitive to NBI.
4 citations
Cites background or methods from "Frequency domain equalization for s..."
...A frequency domain linear equalizer is the frequency domain counterpart of a conventional time domain equalizer [2]....
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...Therefore, SCM with frequency domain equalization has been proposed as an alternative to OFDM [2]....
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...Therefore, frequency domain equalization is proposed for multipath wireless channel in SCM systems [2]....
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...Moreover, it suffers from high sensitivity to carrier frequency offsets and NBI [2], [3]....
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...It offers reduced complexity than a time domain equalizer because equalization is performed on a block of data at a time and operation on this block involves an efficient FFT operation [2]....
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TL;DR: This paper presents a unified approach to blind-channel estimation and interference suppression for block transmission using ZP or CP in both single-carrier (SC) and multicarrier (MC) systems, using a generalized multichannel minimum variance principle to design an equalizing filterbank.
Abstract: Block transmission has recently been considered as an alternative to the conventional continuous transmission technique. In particular, block transmission techniques with zero padding (ZP) and cyclic prefix (CP) are becoming attractive procedures for their ability to eliminate both intersymbol interference (ISI) and interblock interference (IBI). In this paper, we present a unified approach to blind-channel estimation and interference suppression for block transmission using ZP or CP in both single-carrier (SC) and multicarrier (MC) systems. Our approach uses a generalized multichannel minimum variance principle to design an equalizing filterbank. The channel estimate is then obtained from an asymptotically tight lower bound of the filterbank output power. Through an asymptotic analysis of the subspace of the received signal, we determine an upper bound for the number of interfering tones that can be handled by the proposed schemes. As a performance measure, we derive an unconditional Cramer-Rao bound (CRB) that, similar to the proposed blind channel estimators, does not assume knowledge of the transmitted information symbols. Numerical examples show that the proposed schemes approach the CRB as the signal-to-noise ratio (SNR) increases. Additionally, they exhibit low sensitivity to unknown narrowband interference and favorably compare with subspace blind-channel estimators.
4 citations
Additional excerpts
...It was shown in [7] that block SC transmission has similar equalization complexity and coded performance to that of OFDM....
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TL;DR: DRPE and chaotic Baker interleaving are used for efficient video frame transmission over OFDM and channel equalization is implemented in the proposed scheme.
Abstract: Due to the need to transmit encrypted data and video securely through wireless channels, we suggest the application of the double random phase encryption (DRPE) algorithm for efficient video communication over orthogonal frequency division multiplexing (OFDM) system. Moreover, we use an efficient interleaving mechanism on the communicated data depending on chaotic Baker map to control the error level of the channel. In this paper, DRPE and chaotic Baker interleaving are used for efficient video frame transmission over OFDM. Channel equalization is implemented in the proposed scheme. Simulation results illustrate the good performance of the suggested scheme for secure video communication.
4 citations
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