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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29 Nov 2004
TL;DR: The results show that the proposed receiver structure has a good performance, allowing BER close to the MFB (matched filter bound), even with moderate frequency offsets and severe time-dispersive channels.
Abstract: In this paper we consider a broadband wireless system employing SC (single-carrier) modulations combined with FDE (frequency-domain equalization). We propose a receiver structure for joint carrier synchronization and equalization which combines IB-DFE (iterative block decision feedback equalization) and post-equalization carrier synchronization schemes. The proposed receiver can be regarded as a modified IB-DFE where we perform a decision-directed frequency offset estimation within each iteration of the equalizer. Our results show that the proposed receiver structure has a good performance, allowing BER (bit error rate) close to the MFB (matched filter bound), even with moderate frequency offsets and severe time-dispersive channels.
26 citations
Cites methods from "Frequency domain equalization for s..."
...For this reason, a mixed SC/OFDM air interface was proposed [3, 5 ], with an OFDM scheme in the downlink and a SC scheme in the uplink....
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TL;DR: Analytical studies prove that HC modulation scheme achieves a trade-off between circularly prefixed orthogonal frequency division multiplexing and single-carrier systems in terms of resisting doubly-selective fading.
Abstract: A hybrid carrier (HC) system employing a frequency domain linear equalization based on minimum mean square error (MMSE) criterion is analyzed in this letter. The analytical studies prove that HC modulation scheme achieves a trade-off between circularly prefixed orthogonal frequency division multiplexing (OFDM) and single-carrier (SC) systems in terms of resisting doubly-selective fading. By dispersing the aggregated residual interference effectively, the HC system with particular modulation orders outperform OFDM and SC systems within a specific signal noise ratio (SNR) interval. Both analysis and simulation results over a typical double selective fading channel verify the superiority of HC modulation in suppressing residual interferences.
25 citations
Cites background from "Frequency domain equalization for s..."
...EFFORTS have been devoted to the comparisons of singecarrier frequency domain equalization (SC-FDE) and OFDM systems [1]–[3]....
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TL;DR: Simulation results show that in the mobile frequency selective channels the performance of the proposed receivers is comparable to the near optimal list sphere decoding based turbo receiver, and it is very close to that of the single-user in the Gaussian channel.
Abstract: Low complexity space-frequency turbo detection and decoding schemes are proposed for multi-user space-time block-coded (STBC) block transmission systems, including cyclic prefix based single-carrier block transmission (CP-SCBT) system and OFDM system. Using the algebraic properties of these systems, we give the implementation of MMSE- and match-filter-based (MF) turbo detector in the frequency domain. The detector complexity is independent of the channel memory and of the constellation size. To further reduce the complexity, a switched MMSE/MF detector is applied to the turbo receivers. Simulation results show that in the mobile frequency selective channels the performance of the proposed receivers is comparable to the near optimal list sphere decoding based turbo receiver, and it is very close to that of the single-user in the Gaussian channel
25 citations
Cites methods from "Frequency domain equalization for s..."
...Block transmission schemes such as CPSCBT and OFDM have been shown to be the attractive solutions [2], [3]....
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TL;DR: An iterative multiuser detection scheme using frequency-domain equalization (IMDFDE) which can be incorporated into a single carrier frequency division multiple access (SC-FDMA) framework and can obtain diversity gain without sacrificing spectral efficiency and approaches the single-user bound over time-varying and frequency-selective fading relay channels.
Abstract: In this paper, we present an iterative multiuser detection scheme using frequency-domain equalization (IMDFDE), which can be incorporated into a single carrier frequency division multiple access (SC-FDMA) framework. The IMD-FDE scheme employs a different interleaver for each user at the transmitter, and removes multiuser interference with an iterative detection method in the frequency domain at the receiver. The extrinsic information transfer (EXIT) charts and bit-error rate (BER) plots are presented to investigate the iterative behavior of the IMD-FDE over additive white Gaussian noise and multipath fading channels. In a conventional time-division multiple-access (TDMA)-based relay protocol, cooperative transmission over two time slots leads to a 50% loss in spectral efficiency. We propose two spectral efficient relay protocols, where multiple sources access a relay, destination, or both simultaneously. We also present a new iterative detection scheme that effectively removes multiuser interferences for the proposed relay protocols.With the proposed protocols and the aid of iterative multiuser detection scheme, the proposed relay-assisted SC-FDMA with IMD-FDE can obtain diversity gain without sacrificing spectral efficiency and approaches the single-user bound over time-varying and frequency-selective fading relay channels.
25 citations
Cites background from "Frequency domain equalization for s..."
...Single carrier frequency-domain equalization (SC-FDE) has similar performance and essentially the same overall complexity as orthogonal frequency division multiplexing (OFDM) [2], [3]....
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Patent•
03 Mar 2015
TL;DR: In this paper, the authors proposed a method for using a detector to monitor and detect channel occupancy in a network using a framed format having a periodic time structure, where non-cooperative transmissions are detected by the network, and the detector assesses the availability of a backup channel enabling migration of the network.
Abstract: Methods for using a detector to monitor and detect channel occupancy are disclosed. The detector resides on a station within a network using a framed format having a periodic time structure. When non-cooperative transmissions are detected by the network, the detector assesses the availability of a backup channel enabling migration of the network. The backup channel serves to allow the network to migrate transparently when the current channel becomes unavailable. The backup channel, however, could be occupied by another network that results in the migrating network interfering with the network already using the backup channel. Thus, the detector detects active transmission sources on the backup channel to determine whether the backup channel is occupied. Methods for using the detector include scheduling detection intervals asynchronously. The asynchronous detection uses offsets from a reference point within a frame.
25 citations
References
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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