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 Jan 2007
TL;DR: The Thesis presents a method to build the linear space-time dispersion matrices to be used at the transmitter, as a function of the desired dispersionMatrices in the space and frequency domains.
Abstract: This Thesis work gives original contributions to the application of multi-antenna techniques to Frequency Domain Equalization (FDE)-based systems, in particular to Single Carrier Frequency Domain Equalization (SCFDE) systems, which are emerging as an attractive alternative/complement to Orthogonal Frequency Division Multiplexing (OFDM) in future wireless systems. The main focus of the Thesis is the proper application of multi-antenna techniques to SCFDE. In particular, in spite of the many similarities between OFDM and SCFDE systems, multi-antenna techniques operating in the space and frequency domains (either diversityonly, hybrid diversity-multiplexing and advanced Linear Dispersion Codes (LDC)), which represent an attractive solution for OFDM systems in specific propagation scenarios (i.e., highly time variable channels), cannot be easily (i.e., without increasing the transceiver complexity) extended to SCFDE systems. In fact, in SCFDE systems there is no direct access to subcarriers at the transmitter, unless Fast Fourier Transform (FFT) and Inverse Fast Fourier Transform (IFFT) operations are performed, thus greatly increasing the transceiver complexity. The present work overcomes this issue proposing new low-complexity pre-processing techniques (complexity comparable with the one of space-time techniques). Especially interesting it is the extension to SCFDE systems of LDC in the frequency domain: the Thesis presents a method to build the linear space-time dispersion matrices to be used at the transmitter, as a function of the desired dispersion matrices in the space and frequency domains. Performance comparisons prove their suitability in a wide range of propagation scenarios (level of frequency and time diversity of the channel). Moreover, iv
3 citations
Cites background from "Frequency domain equalization for s..."
...This arrangement OFDM in the downlink and SC in the uplink - has two potential advantages [16]: c © Nicola Marchetti, 2007...
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...The signal processing complexities of these two systems are essentially the same for equal FFT block lengths [16]....
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...For tens of Megasymbols per second and more than about 30-50 symbols ISI, the complexity and required digital processing speed become exorbitant, and this TDE approach becomes unattractive [16]....
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TL;DR: Reconfigurable air interfaces, based on frequency domain transmission and reception methods, best meet requirements, by adaptively selecting the uplink and downlink modulation and multiple access scheme that is most appropriate for the channel, interference, traffic and cost constraints.
Abstract: generation cellular wireless systems, transporting high bit rates in non-ideal radio propagation environments, must be robust to severe frequency selective multipath. Further requirements include moderate terminal and base station hardware costs, high spectral efficiency, and scalability of the cost of terminals with respect to their maximum bit rate capabilities. Reconfigurable air interfaces, based on frequency domain transmission and reception methods, best meet these requirements, by adaptively selecting the uplink and downlink modulation and multiple access scheme that is most appropriate for the channel, interference, traffic and cost constraints. This approach also leads to a general unified framework for possible air interfaces.
3 citations
19 May 2008
TL;DR: A symbol- level frequency domain equalizer and spread-spectrum mode are jointly designed to maximize the diversity gain with low complexity and can be applied to direct sequence code division multiple access (DS-CDMA), multi-carrier CDMA, and orthogonal frequency divisionmultiple access (OFDMA) systems.
Abstract: Design of equalizers and spread-spectrum modes or code allocation schemes is crucial for achieving good performance multi-code multiple access systems. In this paper, a symbol- level frequency domain equalizer and spread-spectrum mode are jointly designed to maximize the diversity gain with low complexity. Since the proposed transceiver scheme is independent of the orthogonal codes, it can be applied to direct sequence code division multiple access (DS-CDMA), multi-carrier CDMA (MC-CDMA) and orthogonal frequency division multiple access (OFDMA) systems. Simulation results are provided which validate the theoretical analysis.
3 citations
Cites background or methods from "Frequency domain equalization for s..."
...FDEs are well-known to be implemented with one-tap equalization using Fourier transforming [6–9]....
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...The system performance can be improved either by allocating the spreading codes in the transmitter [1–3] or by designing multi-user detection algorithms in the receiver [4,5], which are often referred to as equalizers in downlink systems [6–9]....
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24 Oct 2013
TL;DR: This paper describes the system architecture, design methodology and subsequent FPGA mapping of a millimeter wave digital baseband for wireless communication in the 60GHz spectral band to be compliant with the 802.11ad Single Carrier and Control PHY draft specifications.
Abstract: This paper describes the system architecture, design methodology and subsequent FPGA mapping of a millimeter wave digital baseband for wireless communication in the 60GHz spectral band. The baseband is designed to be compliant with the 802.11ad Single Carrier and Control PHY draft specifications and supports a data rate of 2.5Gbps at the physical layer. The demanding throughput and latency requirements are achieved with a parallel implementation. However, due to limited capacity of the FPGAs present in our prototype platform and complex partitioning requirements, only a scaled down version of the full single carrier baseband that operates at 1/10th the throughput of the specification could be mapped. A minimal real-time hardware MAC was also incorporated and coupled with a 60GHz RF beam-forming front-end to demonstrate file transfer between two independent FPGA prototyping systems. A system throughput of 59Mbps was achieved at the application layer using π/2 QPSK modulation with a 13/16 LDPC code rate.
3 citations
Cites methods from "Frequency domain equalization for s..."
...This paper described the design of a 60GHz single carrier digital baseband and trade-offs made to realize a nearly complete wireless system on an FPGA platform consisting of four Virtex5 devices....
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Proceedings Article•
01 Oct 2008TL;DR: The design of the precoding sequence which minimizes the noise effect and numerical error in covariance matrix estimation is proposed andSimulations are used to demonstrate the performance of the blind channel estimation method.
Abstract: We propose a blind channel estimation method for single carrier block transmission systems with frequency domain equalization. The method uses periodic precoding on the source signal before transmission. The estimation of the channel impulse response vector consists of two steps: (1) obtain the channel product matrix by solving a group of decoupled linear equations, and (2) obtain the channel impulse response vector by computing the maximal eigenvalue and the associated eigenvector of a Hermitian matrix formed from the channel product matrix. The identifiability condition is very simple. The design of the precoding sequence which minimizes the noise effect and numerical error in covariance matrix estimation is proposed. Simulations are used to demonstrate the performance of the method.
3 citations
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