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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07 May 2006
TL;DR: The proposed CPS improves its bit error rate (BER) performance, without requiring unrealizable synchronization of transmission-timing control amongst all users, without compromising the multi-user interference (MUI)-free properties.
Abstract: This paper describes a new scrambling method that reduces multi-path interference (MPI), without compromising the multi-user interference (MUI)-free properties. The column-pair scrambling (CPS) method is suitable for iterative data transmission schemes, such as chip-interleaved block spread (CIBS) - code division multiple access (CDMA) or interleaved frequency domain multiple access (IFDMA). The proposed CPS improves its bit error rate (BER) performance, without requiring unrealizable synchronization of transmission-timing control amongst all users. This improvement depends on the number of active users, and the worst BER performance of the CPS will be the same as fully loaded conventional CIBS-CDMA or IFDMA systems. The simulation results also show that the proposed CPS improves BER performance under fading channels.
2 citations
Cites background from "Frequency domain equalization for s..."
...The FDE may be a powerful tool for wide bandwidth wireless access schemes [8], because the circuit size of the equalizer will not be changed depending on the number of multi paths generated by the high-time resolution....
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01 Aug 2015
TL;DR: A novel analog front-end architecture based on complex sub-nyquist sampling for the intermediate frequency (IF) stage of a mmWave receiver and it is shown that digital compensation of the impairments introduced by the non-ideal 90° hybrid coupler is required to use high modulation orders.
Abstract: A novel analog front-end architecture based on complex sub-nyquist sampling for the intermediate frequency (IF) stage of a mmWave receiver is proposed. With this front-end, the use of a wideband hybrid coupler and two half-rate analog-to-digital converters (ADCs) allow for a flexible placement of the IF. It is shown that digital compensation of the impairments introduced by the non-ideal 90° hybrid coupler is required to use high modulation orders. Further a digital signal processing (DSP) architecture is presented which performs equalization of a fractionally spaced sub-sampled IF signal in frequency domain (FD) and integrates the compensation of the impairments with low overhead. Based on this DSP architecture a working 60GHz single-carrier link is demonstrated. Measurement results show the feasibility of 256QAM modulated transmission with a bandwidth of up to 1.8 GHz and a resulting raw data rate of 12.8 Gb/s using our frontend architecture with the digital FD compensation.
2 citations
DOI•
01 Jan 2009
TL;DR: In this paper, the authors propose a method to solve the problem of "uniformity" and "uncertainty" in the context of data mining, and propose a solution.
Abstract: vii
2 citations
03 Dec 2010
TL;DR: Numerical results show that the proposed adaptive scheme always provides the best performance irrespective of the frequency selectivity in channels while itsfrequency selectivity gives some BER degradation in the periodic and non-periodic transmissions.
Abstract: This paper proposes an adaptive single-carrier modulation with frequency domain equalization (SC-FDE) scheme further enhancing frequency diversity benefit. We have so far proposed the periodic spectrum transmission realized by the even-numbered time domain samples, which further improves the bit error rate (BER) of SC-FDE in severe frequency selective fading channels. However, in frequency non-selective fading channels, the periodic spectrum transmission provides worse BER than the traditional non-periodic transmission. Therefore, the proposed adaptive transmission chooses the appropriate transmission mode by comparing the error vector magnitudes (EVM) of the periodic and non-periodic transmissions. Moreover, since the EVM is measured by the CAZAC-based pilot signals used for channel estimation, additional redundancy is not needed any more. Numerical results show that the proposed adaptive scheme always provides the best performance irrespective of the frequency selectivity in channels while its frequency selectivity gives some BER degradation in the periodic and non-periodic transmissions.
2 citations
Cites background from "Frequency domain equalization for s..."
...However, SC-FDE has a drawback of inter-bitinterference (IBI) caused by the loss of orthogonality among different frequency domain samples under the frequency selective fading channels, which leads to the degradation of the transmission performance [1]- [4]....
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TL;DR: Computer simulations confirm that the proposed scheme is effective in suppression of CCI, and frequency domain SC/MMSE Turbo equalizer is employed to suppress ISI due to spectrum nulling process in the transmitter as well as the multipath fading.
Abstract: SUMMARY This paper proposes a frequency domain nulling filter and Turbo equalizer to suppress interference in the uplink of one-cell reuse single-carrier time division multiple access (TDMA) systems. In the proposed system, the desired signal in a reference cell is interfered by interference signals including adjacent-channel interference (ACI), co-channel interference (CCI), and intersymbol interference (ISI). At the transmitter, after a certain amount of spectrum is nulled considering the expected CCI, the suppressed power due to nulling is reallocated to the remaining spectrum components so as to keep the total transmit power constant. In this process, when mitigation of ACI is necessary, after a certain amount of spectrum at both edges is nulled using an edge-removal filter, the aforementioned process is conducted. At the receiver, frequency domain SC/MMSE Turbo equalizer (FDTE) is employed to suppress ISI due to spectrum nulling process in the transmitter as well as the multipath fading. Computer simulations confirm that the proposed scheme is effective in suppression of CCI,
2 citations
Additional excerpts
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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