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: This paper presents the average block error rate (BLER) performance of star 16/64QAM schemes using iterative decision-directed channel estimation (IDDCE) associated with the turbo frequency domain equalizer (FDE) for discrete Fourier transform-precoded Orthogonal Frequency Division Multiple Access (OFDMA).
Abstract: This paper presents the average block error rate (BLER) performance of star 16/64QAM schemes using iterative decision-directed channel estimation (IDDCE) associated with the turbo frequency domain equalizer (FDE) for discrete Fourier transform (DFT)-precoded Orthogonal Frequency Division Multiple Access (OFDMA). We show that the turbo FDE with the IDDCE based on the a posteriori log-likelihood ratio (LLR) decreases the required average received signal-to-noise power ratio (SNR) compared to that based on the extrinsic LLR. We also show that the turbo FDE is effective in decreasing the required average received SNR considering the cubic metric (CM) compared to the linear minimum mean-square error based FF-FDE for star 16/64QAM schemes. Moreover, we show that the (8, 8) star 16QAM and (16, 16, 16, 16) star 64QAM schemes decrease the required average received SNR considering the CM at the average BLER of 10 by approximately 0.8 and 0.3 dB compared to the square 16QAM and 64QAM schemes, respectively, with a low turbo coding rate such as R = 1/3 when using the turbo FDE associated with IDDCE.
1 citations
11 May 2015
TL;DR: This work proposes to use high order QAM constellations combined with envelope control Magnitude Modulation (MM) techniques and bit-interleaved coded modulation with LDPC codes to fulfill requirements for block-based single carrier transmissions.
Abstract: The development of new mobile communications systems faces several important challenges, namely demanding for high bit rates, high spectral efficiency, low energy consumption and the usage of hostile channels. In order to fulfill these requirements for block-based single carrier transmissions, we propose to use high order QAM constellations combined with envelope control Magnitude Modulation (MM) techniques and bit-interleaved coded modulation with LDPC codes. Also, the receiver uses powerful MM specialized IB-DFE solutions to combat the channel distortion and noise. The obtained results have shown significant improvements in terms of energy efficiency and bit error rate.
1 citations
Cites background from "Frequency domain equalization for s..."
...When considering also energy efficiency constraints, block-based SC transmissions, e.g., single-carrier with frequency-domain equalization (SC-FDE) [8], are advantageous because they have a lower PAPR compared to MC transmissions, such as orthogonal frequency division multiplex (OFDM) [9], making them of particular interest for the uplink transmission on mobile communications....
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..., single-carrier with frequency-domain equalization (SC-FDE) [8], are advantageous because they have a lower PAPR compared to MC transmissions, such as orthogonal frequency division multiplex (OFDM) [9], making them of particular interest for the uplink transmission on mobile communications....
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...The adoption of block-based transmission techniques, both singlecarrier (SC) and multi-carrier (MC), added with convenient cycle prefix, and combined with frequency domain equalization (FDE), are particularly suitable to this situation [8], since they can provide goodperformance in severely time-dispersive channels without requiring complex receiver implementations....
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...In this section we propose an IB-DFE system [10] for SC-FDE transmissions employing a general M -QAM constellation, channel coding and MM envelope control....
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16 May 2010
TL;DR: In this paper, the performance of random access in single carrier FDMA (SC-FDMA) system is analyzed in the multipath fading channel environments by exploiting the cross-correlation property of the random access code.
Abstract: In this paper we analyzed random access process of single carrier FDMA (SC-FDMA) system, which is one of uplink candidates in 3GPP long term evolution. In random access process each user equipments (UE) transmits randomly selected random access code and the Node B detects each UE's random access try by code identification. It is conducted by exploiting the cross-correlation property of random access code. Moreover, round trip time (RTT) is also estimated during random access detection process for uplink time synchronization utilizing the auto-correlation of random access code. This paper proposed random access detection scheme which adopts the frequency domain RTT estimation and the time domain code identification. The performance of random access of SC-FDMA system highly depends on correlation properties. However, they are susceptible to channel characteristics in the multipath fading channel environments. Thus, this paper analyzed the performance of random access in the multipath fading channel. Results of our analysis will be beneficial as the guideline in designing SC-FDMA based random access system.
1 citations
Patent•
15 Oct 2002TL;DR: In this paper, a soft-in-soft-out (SISO) equaliser for use in a receiver for receiving data from a transmitter configured to transmit from a plurality of transmit antennas simultaneously is described.
Abstract: The invention relates to apparatus, methods and computer program code for equalisation. A soft-in-soft-out (SISO) equaliser for use in a receiver for receiving data from a transmitter configured to transmit data from a plurality of transmit antennas simultaneously is described. The equaliser comprises at least one received signal input for inputting a received signal; a plurality of likelihood value inputs, one for each transmit antenna, for inputting a plurality of decoded signal likelihood values from a SISO decoder; a processor configured to determine from said plurality of signal likelihood values an estimated mean and covariance value for a signal from each of said transmit antennas; an expected signal determiner coupled to said processor to determine an expected received signal value using said mean values; a subtractor coupled to said received signal input to subtract said expected received signal value from said received signal to provide a compensated signal; a filter coupled to said subtractor to filter said compensated signal to provide a plurality of estimated transmitted signal values, one for each said transmit antenna; a filter coefficient determiner coupled to said processor to determine coefficients of said filter using said covariance values; and an output stage coupled to said filter to output a plurality of transmitted signal likelihood values, one for each said transmit antenna, for input to said SISO decoder.
1 citations
28 Jun 2010
TL;DR: A new joint transmit/receive equalization technique for single-carrier block transmissions in a severe frequency-selective fading channel is proposed and the bit error rate (BER) performance is significantly improved by using the proposed scheme.
Abstract: In this paper, we propose a new joint transmit/receive equalization technique for single-carrier (SC) block transmissions in a severe frequency-selective fading channel. An iterative frequency-domain inter-symbol interference cancellation (FDIC) is introduced to the joint transmit/receive (Tx/Rx) frequency-domain equalization (FDE) based on the minimum mean square error (MMSE) criterion which was previously proposed by authors. At a receiver, a 1-tap FDE and FDIC are jointly used and they are updated in an iterative manner to achieve larger frequency diversity gain. Since the transmit FDE weight cannot be updated, we introduce a virtual receiver having a receive FDE & FDIC into the transmitter. In the virtual receiver at the transmitter, the same degree of the residual ISI cancellation is assumed to compute the transmit FDE weight, based on the MMSE criterion, matched to the receive FDE & FDIC. The computer simulation results show that the bit error rate (BER) performance is significantly improved by using our proposed scheme.
1 citations
Cites background from "Frequency domain equalization for s..."
...Frequency-domain equalization (FDE) based on the minimum mean square error (MMSE) criterion is able to overcome the SC transmission problem arising from the severe channel frequency-selectivity [3, 4]....
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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