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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01 Sep 2006
TL;DR: An iterative frequency-domain successive interference cancellation (SIC) with two dimensional (2D) MMSE-FDE is proposed to suppress simultaneously the ISI and the interference from other antennas while obtaining antenna and frequency diversity gain.
Abstract: Broadband wireless packet access will be the core technology of the next generation mobile communication systems. For very high-speed and high-quality packet transmissions in a limited bandwidth, the joint use of multiple-input multiple-output (MIMO) multiplexing and hybrid ARQ (HARQ) is an effective method. However, if single-carrier (SC) transmission is used, the transmission performance significantly degrades due to a large inter-symbol interference (ISI) resulting from a severe frequency-selective fading. In this paper, we propose an iterative frequency-domain successive interference cancellation (SIC) with two dimensional (2D) MMSE-FDE. At each iteration stage, the successive signal detection/cancellation is performed according to the descending order of the signal reliability. However, since the interference from the other transmit antennas can be only partially cancelled by performing SIC, the residual interference is present at the output of SIC. In this paper, we propose to update the 2D MMSE-FDE weights at each signal detection in order to suppress simultaneously the ISI and the interference from other antennas while obtaining antenna and frequency diversity gain. However, since a single use of SIC with 2D MMSE-FDE is insufficient, it is repeated a sufficient number of times. The bit error rate (BER) and HARQ throughput performance in a frequency-selective Rayleigh fading channel are evaluated by computer simulation.
14 citations
Cites background from "Frequency domain equalization for s..."
...Recently, it has been shown that the use of frequency-domain equalization (FDE) can significantly improve the SC transmission performance [3,4]....
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TL;DR: A computer simulation is conducted to investigate the achievable bit error rate (BER) performance and the effectiveness of the proposed iterative transmit/receive equalization technique for single-carrier (SC) block transmission in a severe frequency-selective fading channel.
Abstract: In this paper, we propose a novel iterative transmit/receive equalization technique for single-carrier (SC) block transmission in a severe frequency-selective fading channel. Iterative frequency-domain inter-symbol interference (ISI) cancellation (FDIC) is introduced to the previously proposed joint iterative transmit/receive frequency-domain equalization (FDE) based on the minimum mean square error (MMSE) criterion. 1-tap FDE is employed at the transmitter. At the receiver, a 1-tap FDE and FDIC are jointly used and they are updated in an iterative manner. The transmit FDE weight is derived based on the MMSE criterion by taking into account the reduction of residual ISI in the receiver. To derive the weight, the transmitter assumes that the receiver can partially reduce the residual ISI after the FDIC. We conduct a computer simulation to investigate the achievable bit error rate (BER) performance to confirm the effectiveness of our proposed technique.
14 citations
Cites methods from "Frequency domain equalization for s..."
...We conduct a computer simulation to investigate the achievable bit error rate (BER) performance to confirm the effectiveness of our proposed technique. key words: frequency-domain equalization, interference cancellation, single-carrier...
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Patent•
13 Dec 2007TL;DR: In this paper, a method for generating a continuous phase modulated waveform based on the data symbols is described, and a plurality of coefficients are transmitted via a subcarrier.
Abstract: Various example embodiments are disclosed herein. According to an example embodiment, a method may include receiving a plurality of data symbols, generating a continuous phase modulated waveform based on the data symbols, generating a plurality of coefficients which represent the continuous phase modulated waveform, and wirelessly transmitting the plurality of coefficients via a plurality of subcarriers.
14 citations
Posted Content•
TL;DR: This paper proposes low complexity algorithms based on Markov chain Monte Carlo technique for signal detection and channel estimation on the uplink in large scale multiuser multiple input multiple output (MIMO) systems with tens to hundreds of antennas at the base station (BS) and similar number of uplink users.
Abstract: In this paper, we propose low complexity algorithms based on Markov chain Monte Carlo (MCMC) technique for signal detection and channel estimation on the uplink in large scale multiuser multiple input multiple output (MIMO) systems with tens to hundreds of antennas at the base station (BS) and similar number of uplink users. A BS receiver that employs a randomized sampling method (which makes a probabilistic choice between Gibbs sampling and random sampling in each iteration) for detection and a Gibbs sampling based method for channel estimation is proposed. The algorithm proposed for detection alleviates the stalling problem encountered at high SNRs in conventional MCMC algorithm and achieves near-optimal performance in large systems. A novel ingredient in the detection algorithm that is responsible for achieving near-optimal performance at low complexities is the joint use of a {\it randomized MCMC (R-MCMC) strategy} coupled with a {\it multiple restart strategy} with an efficient restart criterion. Near-optimal detection performance is demonstrated for large number of BS antennas and users (e.g., 64, 128, 256 BS antennas/users). The proposed MCMC based channel estimation algorithm refines an initial estimate of the channel obtained during pilot phase through iterations with R-MCMC detection during data phase. In time division duplex (TDD) systems where channel reciprocity holds, these channel estimates can be used for multiuser MIMO precoding on the downlink. Further, we employ this receiver architecture in the frequency domain for receiving cyclic prefixed single carrier (CPSC) signals on frequency selective fading between users and the BS. The proposed receiver achieves performance that is near optimal and close to that achieved with perfect channel knowledge.
14 citations
Cites background from "Frequency domain equalization for s..."
...We consider cyclic prefixed single-carrier (CPSC) signaling, where the ov rall channel includes a Fourier transform (FFT) operation so that the transmitted symbols are estimat ed from the received frequency-domain signal [39], [40], [41]....
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19 May 2008
TL;DR: Suboptimal SC- FDEs with much lower computational complexity are proposed that achieve the asymptotic MSE of the LMMSE SC-FDEs as the block length tends to infinity.
Abstract: In this paper, linear minimum mean-squared error (LMMSE) frequency domain equalizers (FDEs) are considered for single-carrier (SC) block transmission over additive wide- sense cyclostationary (WSCS) noise. Using the theory of asymptotically equivalent sequences of matrices, it is shown that the mean-squared error (MSE) of cyclic prefix (CP) appended SC- FDE and that of the unique word (UW) appended SC-FDE converge to the same limit as the block length tends to infinity. The closed-form expression of the limit is also derived. Unlike SC-FDEs in additive white Gaussian noise, the computational complexity of the FDEs are as high as that of the time domain equalizers in the presence of the WSCS noise. So, suboptimal SC- FDEs with much lower computational complexity are proposed that achieve the asymptotic MSE of the LMMSE SC-FDEs as the block length tends to infinity. Numerical results are also provided.
14 citations
Cites background from "Frequency domain equalization for s..."
...Lower peak-to-average power ratio (PAPR) and lower sensitivity to carrier frequency offset are most frequently referred ones [1], [2]....
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...Let H be the MN × MN overall channel response matrix that is circulant whose the first column is [h[0], h[1], · · · , h[L− 1], 0, · · · , 0]T , and let v be the MN × 1 WSCS noise vector observed at the output of the receive filter....
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...For the short block, either a cyclic prefix (CP) or a unique word (UW) is widely used [1]....
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...Especially in SC block transmission over frequency selective channels, frequency domain equalizers (FDEs) can be used to greatly reduce the computational complexity in equalizing the received signal [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]....
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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