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 addresses the multiplexing approach, which effectively eliminates the interference between the additional alert channel and the TDMB channel, and confirms that the proposed signaling method effectively offers the emergency alert services in T-DMB1.
Abstract: Mobile broadcasting services are considered effective methods for emergency alert delivery. Terrestrial digital multimedia broadcasting (T-DMB) offers an emergency alert service called automatic emergency alert service (AEAS). However, the conventional AEAS is inefficient in the aspects of alert service channel, disabled T-DMB receiver, and location-based service. Therefore, this paper proposes a novel signaling method in order to overcome the drawbacks of the AEAS. The presented alert system exploits an additional alert channel, which is multiplexed with the conventional T-DMB channel. This paper also addresses the multiplexing approach, which effectively eliminates the interference between the additional alert channel and the TDMB channel. The simulation results confirm that the proposed signaling method effectively offers the emergency alert services in T-DMB1.
11 citations
Cites methods from "Frequency domain equalization for s..."
...[18] method is used in the MS as illustrated in Fig....
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TL;DR: A frequency domain state-space approach to the least squares (LS) estimation for finite impulse response (FIR) system identification is proposed by exploiting the Toeplitz structure of the data matrix, leading to two low-complexity FFT (fast Fourier transform)-based unbiased recursive estimators.
Abstract: A frequency domain state-space approach to the least squares (LS) estimation for finite impulse response (FIR) system identification is proposed by exploiting the Toeplitz structure of the data matrix, leading to two low-complexity FFT (fast Fourier transform)-based unbiased recursive estimators. The proposed recursive estimators are applied to the smoothing estimation of time-varying frequency selective channels in turbo equalization systems, and channel estimation approaches with complexity O(logL) per symbol are developed, where L is the number of channel taps.
11 citations
26 Jun 2006
TL;DR: Simulation results show that when partial CSI is utilized, SC-FDE systems can achieve much higher spectral efficiency than coded OFDM; if both SC- FDE and OFDM systems use one bit CSI per-subchannel, SC -FDE outperforms OFDM obviously.
Abstract: Single carrier with frequency domain equalization (SC-FDE) has been adopted by IEEE 802.16 standard as an alternative technique of orthogonal frequency division multiplexing (OFDM) in physical layer. Reference [1] proposed the SC-FDE system utilizing channel state information (CSI), which can improve the performance through transmitting information on available frequency-domain subchannels; that is, a part of spectrum in the system proposed in [1] is left unused. This paper compares the spectral efficiency of OFDM and SC-FDE, and gives some simulation results under IEEE 802.16 scenario [3]. Simulation results show that when partial CSI is utilized, SC-FDE systems can achieve much higher spectral efficiency than coded OFDM; if both SC-FDE and OFDM systems use one bit CSI per-subchannel, SC-FDE outperforms OFDM obviously.
11 citations
Cites methods from "Frequency domain equalization for s..."
...After that, the SC-FDE receiver converts the signal back to the time domain with IDFT, and accomplishes detection in the time domain [6][8]....
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TL;DR: A novel block-spread code-division multiple access (BS-CDMA) framework is presented whereby user-specific, channel-independent precoding is employed along with special spreading codes to ensure multi-user interference free reception with maximum user load.
Abstract: A novel block-spread code-division multiple access (BS-CDMA) framework is presented whereby user-specific, channel-independent precoding is employed along with special spreading codes to ensure multi-user interference free reception with maximum user load. This framework is presented in a general form, from which other BS-CDMA techniques can be derived. Finally, it is shown that specific precoder and spreading code designs facilitate low-complexity frequency-domain equalization at the receiver.
11 citations
Cites background or result from "Frequency domain equalization for s..."
...In this model, quasi-static fading is assumed; thus, IBI is removed and the block index i can be omitted....
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...In contrast to the system proposed in [3], a guard interval comprising at least L symbols, where L is the memory order of the channel impulse response, is then added to xμ,i prior to transmission to mitigate inter-block interference (IBI) [9]....
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...the precoder is nonredundant (P = K) since the precoding/decoding matrices are square) and the fact that any single-user linear or nonlinear frequencydomain equalizer can be applied to recover the transmitted signal [9]–[11]....
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09 Nov 2003
TL;DR: In this article, the authors quantify the effects of frequency and timing offsets in orthogonal frequency division multiplexing (OFDM) and single carrier systems and compare their relative sensitivities.
Abstract: The purpose of this paper is to quantify the effects of frequency and timing offsets in orthogonal frequency division multiplexing (OFDM) and single carrier systems and to compare their relative sensitivities This is done in two ways First, by simulation and second, by a numerical computation using a method first introduced by Beaulieu We show that the standard approach, which is based on approximating the ICI (or ISI) term as a Gaussian random variable, is inadequate to characterize performance degradation Our results show that the Gaussian approximation can be overly optimistic or overly pessimistic, depending upon the case In contrast the numerical method is shown to agree closely with simulation in all cases While the numerical method used here has been previously employed for calculation with OFDM, it has not been used in the comparison of single carrier and OFDM
11 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