The Experts below are selected from a list of 78 Experts worldwide ranked by ideXlab platform
Rachel Ward - One of the best experts on this subject based on the ideXlab platform.
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on robustness properties of beta encoders and golden ratio encoders
IEEE Transactions on Information Theory, 2008Co-Authors: Rachel WardAbstract:The beta encoder was recently proposed as a quantization scheme for Analog-to-digital (A/D) conversion; in contrast to classical binary quantization, in which each Analog sample xisin[-1, 1] is mapped to the first N bits of its base-2 expansion, beta encoders replace each sample x with its expansion in a base beta between 1
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on robustness properties of beta encoders and golden ratio encoders
arXiv: Numerical Analysis, 2008Co-Authors: Rachel WardAbstract:The beta-encoder was recently proposed as a quantization scheme for Analog-to-digital conversion; in contrast to classical binary quantization, in which each Analog sample x in [-1,1] is mapped to the first N bits of its base-2 expansion, beta-encoders replace each sample x with its expansion in a base beta satisfying 1 < beta < 2. This expansion is non-unique when 1 < beta < 2, and the beta-encoder exploits this redundancy to correct inevitable errors made by the quantizer Component of its circuit design. The multiplier element of the beta-encoder will also be imprecise; effectively, the true value beta at any time can only be specified to within an interval [ beta_{low}, beta_{high} ]. This problem was addressed by the golden ratio encoder, a close relative of the beta-encoder that does not require a precise multiplier. However, the golden ratio encoder is susceptible to integrator leak in the delay elements of its hardware design, and this has the same effect of changing beta to an unknown value. In this paper, we present a method whereby exponentially precise approximations to the value of beta in both golden ratio encoders and beta encoders can be recovered amidst imprecise circuit Components from the truncated beta-expansions of a "test" number x_{test} in [-1,1], and its negative counterpart, -x_{test}. That is, beta-encoders and golden ratio encoders are robust with respect to unavoidable Analog Component imperfections that change the base beta needed for reconstruction.
Robert W Heath - One of the best experts on this subject based on the ideXlab platform.
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low complexity hybrid precoding strategies for millimeter wave communication systems
IEEE Transactions on Wireless Communications, 2016Co-Authors: Cristian Rusu, Roi Mendezrial, Nuria Gonzalezprelcic, Robert W HeathAbstract:Millimeter communication systems use large antenna arrays to provide good average received power and to take advantage of multi-stream MIMO communication. Unfortunately, due to power consumption in the Analog front-end, it is impractical to perform beamforming and fully digital precoding at baseband. Hybrid precoding/combining architectures have been proposed to overcome this limitation. The hybrid structure splits the MIMO processing between the digital and Analog domains, while keeping the performance close to that of the fully digital solution. In this paper, we introduce and analyze several algorithms that efficiently design hybrid precoders and combiners starting from the known optimum digital precoder/combiner, which can be computed when perfect channel state information is available. We propose several low complexity solutions which provide different trade-offs between performance and complexity. We show that the proposed iterative solutions perform better in terms of spectral efficiency and/or are faster than previous methods in the literature. All of them provide designs which perform close to the known optimal digital solution. Finally, we study the effects of quantizing the Analog Component of the hybrid design and show that even with coarse quantization, the average rate performance is good.
Gottfried Magerl - One of the best experts on this subject based on the ideXlab platform.
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equivalent complex baseband model for digital transmitters based on 1 bit quadrature pulse encoding
IEEE Transactions on Circuits and Systems, 2015Co-Authors: Henri Ruotsalainen, Holger Arthaber, Norbert Leder, Bernhard Pichler, Gottfried MagerlAbstract:In this paper an equivalent complex baseband representation of the Analog Component related non-linearity of digital transmitters relying on 1-bit complex baseband encoding is derived. By exploiting the properties of the pulsed RF encoding the novel behavioral modeling technique is able to represent accurately the non-linear memory effects of the power amplification stage. Furthermore, a band-limited kernel technique leads to more efficient modeling of the complete digital transmitter, and to relaxed sampling rate. For the parameter estimation the linear regression, common to Volterra model identification, can be employed. According to the simulation and measurement based verification results, the novel modeling technique excels the state-of-the-art in terms of modeling accuracy. It can be assumed that the given methodology serves both as a basis for future behavioral models and for the development of advanced encoding techniques for linearization purposes.
Cristian Rusu - One of the best experts on this subject based on the ideXlab platform.
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low complexity hybrid precoding strategies for millimeter wave communication systems
IEEE Transactions on Wireless Communications, 2016Co-Authors: Cristian Rusu, Roi Mendezrial, Nuria Gonzalezprelcic, Robert W HeathAbstract:Millimeter communication systems use large antenna arrays to provide good average received power and to take advantage of multi-stream MIMO communication. Unfortunately, due to power consumption in the Analog front-end, it is impractical to perform beamforming and fully digital precoding at baseband. Hybrid precoding/combining architectures have been proposed to overcome this limitation. The hybrid structure splits the MIMO processing between the digital and Analog domains, while keeping the performance close to that of the fully digital solution. In this paper, we introduce and analyze several algorithms that efficiently design hybrid precoders and combiners starting from the known optimum digital precoder/combiner, which can be computed when perfect channel state information is available. We propose several low complexity solutions which provide different trade-offs between performance and complexity. We show that the proposed iterative solutions perform better in terms of spectral efficiency and/or are faster than previous methods in the literature. All of them provide designs which perform close to the known optimal digital solution. Finally, we study the effects of quantizing the Analog Component of the hybrid design and show that even with coarse quantization, the average rate performance is good.
Roi Mendezrial - One of the best experts on this subject based on the ideXlab platform.
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low complexity hybrid precoding strategies for millimeter wave communication systems
IEEE Transactions on Wireless Communications, 2016Co-Authors: Cristian Rusu, Roi Mendezrial, Nuria Gonzalezprelcic, Robert W HeathAbstract:Millimeter communication systems use large antenna arrays to provide good average received power and to take advantage of multi-stream MIMO communication. Unfortunately, due to power consumption in the Analog front-end, it is impractical to perform beamforming and fully digital precoding at baseband. Hybrid precoding/combining architectures have been proposed to overcome this limitation. The hybrid structure splits the MIMO processing between the digital and Analog domains, while keeping the performance close to that of the fully digital solution. In this paper, we introduce and analyze several algorithms that efficiently design hybrid precoders and combiners starting from the known optimum digital precoder/combiner, which can be computed when perfect channel state information is available. We propose several low complexity solutions which provide different trade-offs between performance and complexity. We show that the proposed iterative solutions perform better in terms of spectral efficiency and/or are faster than previous methods in the literature. All of them provide designs which perform close to the known optimal digital solution. Finally, we study the effects of quantizing the Analog Component of the hybrid design and show that even with coarse quantization, the average rate performance is good.