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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31 Aug 2012
TL;DR: An iterative receiver with joint symbol detection and phase-noise decision-directed estimation where the a posteriori phase noise probability density function is approximate by a weighted sum of Gaussian functions.
Abstract: In this paper we consider the use of single carrier modulations combined with frequency-domain equalization schemes (SC-FDE) in doubly selective channels where the channel variations are due to both phase noise and carrier frequency offset (CFO). Since carrier phase variations within the block duration can compromise significantly the performance of block transmission techniques. We propose an iterative receiver with joint symbol detection and phase-noise decision-directed estimation where we approximate the a posteriori phase noise probability density function by a weighted sum of Gaussian functions.
5 citations
Cites background from "Frequency domain equalization for s..."
...OFDM is particularly interesting for broadcasting systems [1] and the downlink of cellular systems [2], while SC-FDE is especially interesting for the uplink transmission [3]....
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TL;DR: It is proved that the performance of the FDE-SUD is practically identical to that of linear MUD for a fully loaded UMTS cell and a common receiver structure for CDMA, time division multiple access (TDMA), orthogonal frequency division multiplexing (OFDM) and multi-carrier CDMA (MC-CDMA) systems is constructed.
Abstract: The present paper introduces frequency domain equalisation (FDE) as an efficient means for single-user detection (SUD) in universal mobile telecommunication systems (UMTS) handhelds. Such an SUD is, at least partially, able to remove multiple access interference (MAI) like a multi-user detector (MUD), however with several important advantages
the operation principle of an FDE-SUD is simple and easy to understand,
the FDE-SUD shows low numerical complexity and therefore,
it is not power hungry like an MUD.
The problem of applying FDE without zero-padding or cyclic-prefix insertion is solved by using the overlap-cut method. In this paper we also prove that the performance of the FDE-SUD is practically identical to that of linear MUD for a fully loaded UMTS cell. Furthermore, armed with the idea of FDE for code division multiple access (CDMA), we can construct a common receiver structure for CDMA, time division multiple access (TDMA), orthogonal frequency division multiplexing (OFDM) and multi-carrier CDMA (MC-CDMA) systems. This is an extremely useful idea in enabling a software-defined radio (SDR) which can operate seamlessly in several environments such as UMTS, the IEEE 802.11a and WiMaX. FDE based receivers could be one important building-block for the next generation mobile communications. Copyright © 2008 John Wiley & Sons, Ltd.
5 citations
16 May 2005
TL;DR: It is shown that the conventional time domain equalization can be implemented in the frequency domain, thus a multimode receiver that can handle both UMTS and OFDM systems in one equalization structure is feasible.
Abstract: In this paper, a new chip-level MMSE frequency domain equalizer (FDE) is investigated for the downlink frequency division duplex (FDD) mode in UMTS (Universal Mobile Telephone System) The multiple access interference (MAI) and inter chip interference (ICI) can be reduced at the chip level before despreading For frequency domain equalization, the cyclicity of the received block signal needs to be reconstructed if neither cyclic prefix nor zero-padding are used at the transmitter We exploit the relationship between the reconstructed part and the equalized signal itself and derive a self cyclic reconstruction scheme Performance of the proposed MMSE-FDE is shown by computer simulations, compared with performance of FDE with perfect reconstructions It is shown that the conventional time domain equalization can be implemented in the frequency domain, thus a multimode receiver that can handle both UMTS and OFDM systems in one equalization structure is feasible
5 citations
Cites background from "Frequency domain equalization for s..."
...Orthogonality of the signal from the basestation is restored at chip-level....
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...The number of pilot chips differs from 64 to 2048 according to different slot formats [3]....
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15 Oct 2007
TL;DR: A novel multiuser detection (MUD) technique that can separate the signals regardless of the difference in the arrival timing between MTs with an acceptable level of calculation complexity is proposed.
Abstract: Single-carrier (SC) transmission with frequency- domain equalization (FDE) is expected to expand the service area of wireless communication systems by taking advantage of its lower peak-to-average power ratio (PAPR) compared to when using orthogonal frequency division multiplexing (OFDM). In the uplink, the transmit timing difference among the signals from multiple mobile terminals (MTs) becomes significant in a large service area. If the difference in arrival timing among MTs exceeds the cyclic prefix (CP) length, it is difficult to separate the signal of each MT and the transmission quality is severely degraded. In this paper, we propose a novel multiuser detection (MUD) technique that can separate the signals regardless of the difference in the arrival timing between MTs with an acceptable level of calculation complexity. The achievable bit error rate (BER) performance is evaluated by computer simulation in a frequency selective fading channel and the results confirm the effectiveness of the proposed method.
5 citations
Cites result from "Frequency domain equalization for s..."
...Thus, SCFDE promises to support a larger service area than that of OFDM [3]....
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...Multiuser Detection Method for Single-Carrier Transmission in Uplink Multiuser MIMO Access Koichi ISHIHARA, Yasushi TAKATORI, and Shuji KUBOTA NTT Network Innovation Laboratories, NTT Corporation, Yokosuka, Japan E-mail: ishihara.koichi@lab.ntt.co.jp Abstract—Single-carrier (SC) transmission with frequencydomain equalization (FDE) is expected to expand the service area of wireless communication systems by taking advantage of its lower peak-to-average power ratio (PAPR) compared to when using orthogonal frequency division multiplexing (OFDM)....
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...SC-MIMO transmissions with FDE [2] can be applied to uplink multiuser MIMO systems....
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...Therefore, this paper focuses on the combination of SCFDE with multiuser MIMO in the uplink....
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...Keywords- Single-carrier, Frequency-domain equalization (FDE), Multiuser detection (MUD), Multiuser MIMO, Cyclic prefix (CP) I. INTRODUCTION Single-carrier (SC) transmission with frequency-domain equalization (FDE) [1]-[3] is an attractive candidate for the uplink in next generation wireless access systems because SCFDE attains a transmission quality level comparable to that of orthogonal frequency division multiplexing (OFDM) [4] while achieving a lower peak-to-average power ratio (PAPR) compared to that for OFDM....
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19 May 2008
TL;DR: Simulation results show that the proposed algorithm achieves the best trade-off between BER performance and computational complexity compared to other existing methods.
Abstract: This paper proposes an efficient turbo frequency domain equalizer (FDE) for single carrier systems with cyclic-prefix (CP). At each iteration, the proposed algorithm performs soft inter-symbol interference (ISI) cancellation and symbol-wise minimum mean-square error (MMSE) filtering both in the frequency domain to minimize the performance degradation caused by frequency-selective channels. After the one-tap frequency domain filtering, the assumption of an equivalent additive white Gaussian noise (AWGN) channel is used to compute the extrinsic log likelihood ratios (LLRs) of coded bits as the inputs of soft-in soft-out (SISO) decoder. Simulation results show that our proposed algorithm achieves the best trade-off between BER performance and computational complexity compared to other existing methods.
5 citations
Cites background from "Frequency domain equalization for s..."
...However, unlike OFDM, SC-FDE does not suffer high peak-to-average power ratio (PAPR) as well as sensitivity to frequency and phase offsets [1]....
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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]....
[...]
...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 ]....
[...]
...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 ]....
[...]
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