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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Journal Article•
TL;DR: A pilot-assisted channel estimation scheme suitable for OFDM/TDM with MMSE-FDE is presented and the achievable BER performance is evaluated by computer simulation.
Abstract: Orthogonal frequency division multiplexing (OFDM) combined with time division multiplexing (TDM), called OFDM/TDM, can overcome the high peak-to-average-power ratio (PAPR) problem of the conventional OFDM. Its bit error rate (BER) performance in a frequency-selective fading channel is improved by adoption of frequency-domain equalization (FDE) based on minimum mean square error (MMSE) criterion. However, MMSE-FDE requires accurate channel estimation. In this paper, a pilot-assisted channel estimation scheme suitable for OFDM/TDM with MMSE-FDE is presented and the achievable BER performance is evaluated by computer simulation. Keyword: OFDM/TDM, frequency-domain equalization, pilot-assisted channel estimation.
2Â citations
Cites background from "Frequency domain equalization for s..."
...(2), H(k), Es and * represent the kth frequency channel gain, the symbol energy and the complex conjugate operation, respectively....
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TL;DR: The proposed hybrid scheme does not have channel codec but simulation results show it has better performances in comparison with the coded OFDM algorithm at the expense of algebraic calculations and FFT executions.
Abstract: This paper proposes a hybrid shortened transmission/expanding reception technique and single carrier modulation with a zero forcing frequency domain equalizer when a single carrier modulation with a guard period is transmitted. Regarding single carrier transmission data as shortened OFDM transmission data allows an expanding reception technique and a maximum ratio to be combined in the receiver, and a parallel single carrier modulation with a frequency domain equalizer is used as a secondary receiver. The proposed hybrid scheme does not have channel codec but simulation results show it has better performances in comparison with the coded OFDM algorithm at the expense of algebraic calculations and FFT executions.
2Â citations
Cites methods from "Frequency domain equalization for s..."
...This paper proposes a hybrid STT/ERT and SC-FDE technique for single carrier transmission data with a guard period, and its transmission symbols are derived analytically to be the same as shortened transmission technology’s OFDM transmission symbols....
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...Therefore hardware complexity is 64*(9/64)+2(SC-FDE) = 11 for channel A case and 24 for channel C case....
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...In this paper, we propose a hybrid STT/ERT and SC-FDE (ZF) technique for a single carrier transmission with a guard period, simulate it in HiperLAN/2 channel A and C, and show the results....
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...The second receiver is an SC-FDE (ZF) receiver which consists of wrapping around and addition, FFT, channel compensation, and an IFFT block....
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...Even though this modified ERT helps to reduce propagation errors, there is still an unresolved divergence problem in the ERT receiver, and so the conventional single carrier modulation with zero forcing frequency domain equalization technique, SC-FDE [5], is used as a secondary algorithm....
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TL;DR: The IVSS (Intelligent Voice Service System) is constituted with voice rafting business and fixed telephone business like the authors chat, which is constructed by voice acquisition, number identification, voice feedback and customer information processing module.
Abstract: Its based on the voice value-added business booming and combined with the value-added service of mobile and network so that the fixed telephone intelligent voice service system is put forward in the paper. The system is constituted with voice rafting business and fixed telephone business like we chat, which is constructed by voice acquisition, number identification, voice feedback and customer information processing module. The rafting business is devoted to solve the difficulty that the users have communication impediment in different time domain. And the business is used availably for work and amusement through orientation conveying or not. The applied range of we chat is broadened because of the fixed telephone business like we chat. The fixed telephone business like we chat is realized by the store-and-forward way to achieve the communication with real time and different time domain. The birth of the new business model will bring consumers the different experience and feelings. The general control scheme, general structure, software modules, business content and running process are included in the paper of the detailed content, and then make the analysis of the dominance of the IVSS (Intelligent Voice Service System).
2Â citations
01 Sep 2009
TL;DR: A new subcarrier mapping method is proposed by which one turbo coded stream is transmitted from multiple frequency bands of Nx SC-FDMA system to achieve multiple-branch frequency diversity gain.
Abstract: Nx SC-FDMA has been accepted as one of the main multiple access schemes for LTE-Advanced, which has been attracted much attention for supporting extended bandwidth. The classical transmit antenna diversity technique as Space-Frequency Block Coding (SFBC) will destroy the order and structure of the original symbols and thus enhance the peak-to-average power ratio (PAPR). To solve this problem, a modified scheme of SFBC compatible with low PAPR is proposed in this paper. In order to achieve more diversity gain, a new subcarrier mapping method is proposed by which one turbo coded stream is transmitted from multiple frequency bands of Nx SC-FDMA system. The proposed SFBC scheme is based on the groups rather than the symbols which remains the same signal distribution as the equivalent conventional transmission to reduce the PAPR. Due to the channel varying in frequency domain during one turbo coded stream, the new subcarrier mapping method has mapped the one turbo coded stream to the different frequency bands to achieve multiple-branch frequency diversity gain. Simulation results show that the proposed transmit diversity scheme has good PAPR and Block Error Rate (BLER) on frequency selective MIMO channels.
2Â citations
Cites background from "Frequency domain equalization for s..."
...INTRODUCTION Single carrier frequency division multiple access (SCFDMA) can be regarded as discrete Fourier transform (DFT)spread OFDMA, where time domain data symbols are transformed to frequency domain by DFT before going through OFDMA modulation [1-2]....
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Dissertation•
27 Sep 2017
TL;DR: This thesis has developed resource allocation and adaptive precoding schemes for both the downlink (DL) and uplink (UL) of the multiuser MIMO-OFDM CR network that are characterized by both computational and spectral efficiencies.
Abstract: In this thesis, we develop efficient resource allocation and adaptive precoding schemes for two scenarios: multiuser MIMO-OFDM and multiuser MIMO based CR networks. In the context of the multiuser MIMO-OFDM CR network, we have developed resource allocation and adaptive precoding schemes for both the downlink (DL) and uplink (UL). The proposed schemes are characterized by both computational and spectral efficiencies. The adaptive precoder operates based on generating degrees of freedom (DoF). The resource allocation has been formulated as a sum-rate maximization problem subject to the upper-limit of total power and interference at primary user constraints. The formulated optimization problem is a mixed integer programming having a combinatorial complexity which is hard to solve, and therefore we separated it into a two-phase procedure to elaborate computational efficiency: Adaptive precoding (DoF assignment) and subcarrier mapping. From the implementation perspective, the resource allocation of the DL is central based processing, but the UL is semi-distributed based. The DL and UL problems are sorted out using the Lagrange multiplier theory which is regarded as an efficient alternative methodology compared to the convex optimization theory. The solution is not only characterized by low-complexity, but also by optimality. Numerical simulations illustrate remarkable spectral and SNR gains provided by the proposed schemes.
2Â 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.
16,062Â 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.
2,627Â 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. >
1,816Â 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.
1,624Â citations