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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26 Dec 2007
TL;DR: A joint formulation of the frequency- domain OFDM and SC MMSE turbo equalizer is proposed which enable to bring out similarities and differences between the two transmission schemes.
Abstract: In this paper, performance comparison of frequency-domain (FD) minimum mean square error (MMSE) turbo equalization for OFDM and single-carrier (SC) transmission in ST-BICM systems is investigated. In particular, we propose a joint formulation of the frequency- domain OFDM and SC MMSE turbo equalizer which enable to bring out similarities and differences between the two transmission schemes. This provides a new view on the topic. The relevance of the proposed approach is confirmed by comparing the lower bound of the iterative equalizing process with the corresponding analytical results. Simulation results over multipath Rayleigh block fading channels for various MIMO configurations show the benefits provided by each scheme.
2 citations
01 Oct 2015
TL;DR: The proposed channel parameters estimation design for Single Carrier Frequency Domain Equalization (SC-FDE) in High Frequency (HF) wireless communications has much better precision and provides the safeguard for subsequent equalization algorithm.
Abstract: This paper proposes an efficient channel parameters estimation design for Single Carrier Frequency Domain Equalization (SC-FDE) in High Frequency (HF) wireless communications. This design is implemented to improve the performance of existing channel estimation by integrating and optimizing traditional channel statistical characteristics estimation. Based on the Synchronization Training Sequences (STS) structure of estimation, our design is able to overcome Inter-Symbol Interference (ISI) and reduce the signal-to-noise ratio (SNR). The proposed algorithm has much better precision and provides the safeguard for subsequent equalization algorithm. Meanwhile, the performance of the proposed algorithm has been compared with existing algorithms. The comparing results show that we can have excellent performance.
2 citations
Cites background from "Frequency domain equalization for s..."
...SC-FDE can combine advantages of Single Carrier (SC) and Orthogonal Frequency Division Multiplexing (OFDM) [1]....
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...Moreover SC-FDE has lower peak -to-average power ratio (PARP) and less sensitivity to carrier frequency errors than OFDM....
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Patent•
24 Jan 2020
TL;DR: In this paper, an enhanced discrete Fourier transform spread orthogonal frequency division multiplexing (DFT-s-OFDM) was proposed to increase processing gain and reduce peak-to-average power ratio (PAPR).
Abstract: Enhanced discrete Fourier transform spread Orthogonal Frequency Division Multiplexing (DFT-s-OFDM) selects spreading code roll-off factors based on available spectrum resources in a wireless network and power efficiency needs of at least one wireless device. Excess spectral resources can be used to increase processing gain and reduce peak-to-average power ratio (PAPR), both of which improve a wireless device's power efficiency. Each layer can employ a portion of the DFT-s-OFDM code space in an OFDM symbol for orthogonal multiple access or non-orthogonal multiple access, allowing multiple layers to share the same OFDM symbol. Both uplink and downlink transmissions can benefit from frequency diversity and low PAPR due to DFT-s-OFDM spreading. Since DFT-s-OFDM codes are cyclic shifts of each other, a DFT-s-OFDM discrete-time signal can be synthesized from cyclic shifts of a kernel discrete-time waveform.
2 citations
18 Jul 2015
TL;DR: In this article, a modified SCFDMA based on using Hadamard transform instead of Fast Fourier Transform (FFT) was proposed for uplink scenario of LTE and the proposed scheme reduced peak-to-average power ratio (PAPR) while the BER does not degraded.
Abstract: The power consumption is an essential issue for designers of mobile devices. Orthogonal Frequency Division Multiplexing (OFDM) suffers from its Peak – to – Average Power Ratio (PAPR) problem. The Discrete Fourier Transmission Spread OFDM (DFTS-OFDM) based on Single Carrier Frequency Division Multiple Access (SC-FDMA) has been widely adopted due to its lower peak-to-average power ratio (PAPR) of transmits signals compared with OFDM. There are three types of mapping in SCFDMA. These namely Localized FDMA (LFDMA), Distributed FDMA (DFDMA), and Interleaved FDMA (IFDMA). In this paper, we propose a modified SCFDMA. This is based on using Hadamard transform instead of Fast Fourier Transform (FFT). Utilizing LFDMA Mapping techniques this is proposed for uplink scenario of LTE. Simulation results show that the proposed scheme reduces PAPR compared to the conventional SCFDMA while the BER does not degraded.
2 citations
Cites background from "Frequency domain equalization for s..."
...Orthogonal frequency division multiple access (OFDMA) is an attractive technology to deal with the detrimental effects of multipath fading, but it has several inherent drawbacks such as the large peak-to-average-power ratio (PAPR) and the sensitivity to carrier frequency offsets [1, 2]....
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05 Jun 2011
TL;DR: An effective way of improving the performance of channel estimation for MIMO single-carrier block transmission (SCBT) systems by utilizing the property that the shift of the cyclic pilot signal of each antenna branch can also be utilized to catch the channel information as a new pilot.
Abstract: In this paper, we propose an effective way of improving the performance of channel estimation for MIMO single-carrier block transmission (SCBT) systems. The proposed method utilizes the property that the shift of the cyclic pilot signal of each antenna branch can also be utilized to catch the channel information as a new pilot. The receiver can continuously estimate the channel information by just shifting the received pilot signal. The channel estimation performance is improved by averaging all channel estimators because this averaging process can reduce the power of noise component. Regardless of the signal-to-noise ratio (SNR) and the pilot type, the proposed method can achieve about a 1.72 dB performance gain in term of the mean squared error (MSE) of channel estimation for each antenna branch with slightly computational complexity. The proposed method can be also utilized to most channel estimation methods for the MIMO SCBT system.
2 citations
Cites background from "Frequency domain equalization for s..."
...In addition, another broadband communication technique has been the focus of much attention, that is, single carrier (SC) with frequency domain equalization (FDE) [2]....
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..., xs,N−1] for sth transmit antenna and s ∈ [1, 2]....
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...The SC-FDE systems can realize equal complexity and performance to OFDM systems without the high peak-toaverage power (PAPR) problem that plagues OFDM systems....
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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 ]....
[...]
...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