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
More filters
TL;DR: The simulation results demonstrate that the online LSTM estimator outperforms Le least Square (LS) and Recursive Least Square (RLS) estimators in terms of Bits Error Rate (BER) and Mean Square Error (MSE).
Abstract: The long distance high frequency (HF) communication suffers from time varying multipath fading. Multiple-Input Multiple-Output (MIMO) and Single-Carrier Frequency Domain Equalization (SC-FDE) have been introduced to HF communication system to combat fading. Because accurate channel estimation is essential for system operation, an architecture of signal flow chart has been designed for the HF MIMO SC-FDE system. In the architecture, an online Long Short-Term Memory (LSTM) estimator is proposed. Different from the channel responses time series created by the LSTM training and prediction loop, a corrected channel responses that are obtained through the received data symbols and the restored transmitting data symbols make up the channel responses time series. In order to evaluate the performance of channel estimators, a simulation system has been built. The uncorrelated and correlated channels are simulated referring to International Telecommunication Union (ITU)-R F.1487 standard and Kronecker model. The simulation results demonstrate that the online LSTM estimator outperforms Least Square (LS) and Recursive Least Square (RLS) estimators in terms of Bits Error Rate (BER) and Mean Square Error (MSE). The online LSTM estimator is capable of tracking the time varying HF MIMO channels. It has potentiality in actual long distance HF communication.
7 citations
Cites result from "Frequency domain equalization for s..."
...The conclusion that SC-FDE has the similar performance and complexity as OFDM was proved in [7], [8]....
[...]
TL;DR: This paper designs the channel shortener to maximize a mutual information lower bound based on a mismatched detection model for a reduced-state soft-output Viterbi equalizer (RS-SOVE) in single-carrier systems.
Abstract: We consider optimal channel shortener design for a reduced-state soft-output Viterbi equalizer (RS-SOVE) in single-carrier systems. To use RS-SOVE, three receiver filters need to be designed: a prefilter, a target response, and a feedback filter. The collection of these three filters are commonly referred to as the “channel shortener.” Conventionally, the channel shortener is designed to transform an intersymbol interference (ISI) channel into an equivalent minimum-phase equivalent form. In this paper, we design the channel shortener to maximize a mutual information lower bound based on a mismatched detection model. By taking the decision-feedback quality in the RS-SOVE into consideration, the prefilter and feedback filter are found in closed forms, while the target response is optimized via a gradient-ascending approach with the gradient explicitly derived. The information theoretical properties of the proposed channel shortener are analyzed. Moreover, we show through numerical results that the proposed channel shortener design achieves superior detection performance compared with previous channel shortener designs at medium and high code rates.
7 citations
Cites background from "Frequency domain equalization for s..."
...2685380 synchronization, and the absence of cyclic-prefix (CP) overhead favor its use in many low data rate scenarios over multicarrier (MC) systems [5], [6]....
[...]
19 May 2008
TL;DR: It is shown that the use of the linear precoding enhances the separability of the EXIT planes of the simultaneous streams over without precoding, which invokes the idea that different code rate be allocated to the each transmitted streams at the transmitter.
Abstract: In this the paper, impact of minimum mean squared error (MMSE) based linear precoding on the convergence of iterative multiuser detector in multiuser multiple input multiple output (MIMO) uplink single carrier communications is studied. The influence of linear precoding on iterative MMSE based multiuser detector is investigated via the multi-dimensional EXIT analysis. It is shown that the use of the linear precoding enhances the separability of the EXIT planes of the simultaneous streams over without precoding; This invokes the idea that different code rate be allocated to the each transmitted streams at the transmitter. Especially, in the case of multiuser communication precoding has significant roles in the convergence property of iterative detector.
7 citations
Cites background from "Frequency domain equalization for s..."
...Since the cyclic-prefix burst transmission technique is very well known [12], its details are not described in this paper....
[...]
10 Oct 2011
TL;DR: This paper analyzes the performance of MIMO-OFDM systems with independent phase noise at transmit and receive antennas using zero-forcing (ZF) detectors over frequency selective Rayleigh fading channels using approximation to the distribution of central complex Wishart distribution to derive signal-to-interference-plus-noise ratio (SINR) the system.
Abstract: in this paper we analyzes the performance of MIMO-OFDM systems with independent phase noise at transmit and receive antennas using zero-forcing (ZF) detectors over frequency selective Rayleigh fading channels. Approximation to the distribution of central complex Wishart distribution is used to derive signal-to-interference-plus-noise ratio (SINR) the system. So the bit error rate (BER) of the system can be denoted based on the analysis of the inter-carrier-interference (ICI) due to phase noise. Simulation results illustrate that the theoretical analysis is quite accurate in Rayleigh fading channels.
7 citations
TL;DR: The results show that, for current typical system parameters, the FD-MRC/OFDM scheme achieves higher total energy efficiency than that achieved by the TR-M RC/SC scheme, however, if the cell radius is less than 300 m and/or the computational efficiency increases by 30% regarding the current processors, the TR -MRC algorithm under SC waveform becomes a much more attractive alternative for the UL of maMIMO systems.
Abstract: This paper proposes a detailed investigation on the uplink (UL) performance of massive multiple-input-multiple-output (maMIMO) systems employing maximum-ratio combining (MRC) at the receiver. While most papers in maMIMO literature assume orthogonal frequency-division multiplexing (OFDM), current standards such as long-term evolution (LTE) employ single-carrier (SC) waveform in the UL because of several benefits. We, thus, perform a systemic comparison between two fundamental schemes: the time-reversal MRC (TR-MRC) operating under SC, and the frequency-domain MRC (FD-MRC) employed with OFDM. On the one hand, it was recently shown that the TR-MRC outperforms the FD-MRC in terms of achievable rates, since SC systems do not require the cyclic prefix of OFDM. On the other hand, the computational complexity of the TR-MRC algorithm is higher than that of the FD-MRC algorithm, even when efficient solutions are employed (e.g., fast convolution with the overlap-and-add method). Hence, the best scheme for the UL maMIMO systems still remains an open question. The main contribution of this paper is the comparison of the total energy efficiency of both the TR-MRC and FD-MRC algorithms when used in the UL of maMIMO systems. Our results show that, for current typical system parameters, the FD-MRC/OFDM scheme achieves higher total energy efficiency than that achieved by the TR-MRC/SC scheme. However, if the cell radius is less than 300 m and/or the computational efficiency increases by 30% regarding the current processors, the TR-MRC algorithm under SC waveform becomes a much more attractive alternative for the UL of maMIMO systems.
7 citations
Cites background from "Frequency domain equalization for s..."
...Several advantages of employing an SC in the UL instead of OFDM can be highlighted [6], [7], such as the following: 1) the transmit signal lower peak-to-average power ratio (PAPR), which results in cheaper and more energy-efficient mobile terminals (MTs)....
[...]
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]....
[...]
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