The Experts below are selected from a list of 2748 Experts worldwide ranked by ideXlab platform

Stephen V Hanly - One of the best experts on this subject based on the ideXlab platform.

  • precoding for the sparsely spread mc cdma downlink with Discrete Alphabet inputs
    arXiv: Information Theory, 2017
    Co-Authors: Chunshan Liu, Stephen V Hanly
    Abstract:

    Sparse signatures have been proposed for the CDMA uplink to reduce multi-user detection complexity, but they have not yet been fully exploited for its downlink counterpart. In this work, we propose a Multi-Carrier CDMA (MC-CDMA) downlink communication, where regular sparse signatures are deployed in the frequency domain. Taking the symbol detection point of view, we formulate a problem appropriate for the downlink with Discrete Alphabets as inputs. The solution to the problem provides a power-efficient precoding algorithm for the base station, subject to minimum symbol error probability (SEP) requirements at the mobile stations. In the algorithm, signature sparsity is shown to be crucial for reducing precoding complexity. Numerical results confirm system-load-dependent power reduction gain from the proposed precoding over the zero-forcing precoding and the regularized zero-forcing precoding with optimized regularization parameter under the same SEP targets. For a fixed system load, it is also demonstrated that sparse MC-CDMA with a proper choice of sparsity level attains almost the same power efficiency and link throughput as that of dense MC-CDMA yet with reduced precoding complexity, thanks to the sparse signatures.

  • precoding for the sparsely spread mc cdma downlink with Discrete Alphabet inputs
    IEEE Transactions on Vehicular Technology, 2017
    Co-Authors: Chunshan Liu, Stephen V Hanly
    Abstract:

    Sparse signatures have been proposed for the code-division multiple-access (CDMA) uplink to reduce multiuser detection complexity, but they have not yet been fully exploited for its downlink counterpart. In this paper, we propose multicarrier CDMA (MC-CDMA) downlink communication whereby regular sparse signatures are deployed in the frequency domain. Taking the symbol detection point of view, we formulate a problem appropriate for the downlink with Discrete Alphabets as inputs. The solution to the problem provides a power-efficient precoding algorithm for the base station (BS), subject to minimum symbol error probability (SEP) requirements at the mobile stations (MSs). In the algorithm, signature sparsity is shown to be crucial for reducing precoding complexity. Numerical results confirm system-load-dependent power reduction gain from the proposed precoding over the zero-forcing (ZF) precoding and the regularized ZF (RZF) precoding with optimized regularization parameter under the same SEP targets. For a fixed system load, it is also demonstrated that sparse MC-CDMA with a proper choice of sparsity level attains almost the same power efficiency and link throughput as that of dense MC-CDMA yet with reduced precoding complexity due to the sparse signatures.

Michelle Effros - One of the best experts on this subject based on the ideXlab platform.

  • on the equivalence of shannon capacity and stable capacity in networks with memoryless channels
    International Symposium on Information Theory, 2011
    Co-Authors: Hongyi Yao, Michelle Effros
    Abstract:

    An equivalence result is established between the Shannon capacity and the stable capacity of communication networks. Given a Discrete-time network with memoryless, time-invariant, Discrete-output channels, it is proved that the Shannon capacity equals the stable capacity. The results treat general demands (e.g., multiple unicast demands) and apply even when neither the Shannon capacity nor the stable capacity is known for the given demands. The result also generalize from Discrete-Alphabet channels to Gaussian channels.

  • Quantization as Histogram Segmentation: Optimal Scalar Quantizer Design in Network Systems
    IEEE Transactions on Information Theory, 2008
    Co-Authors: D Muresan, Michelle Effros
    Abstract:

    An algorithm for scalar quantizer design on Discrete-Alphabet sources is proposed. The proposed algorithm can be used to design fixed-rate and entropy-constrained conventional scalar quantizers, multiresolution scalar quantizers, multiple description scalar quantizers, and Wyner-Ziv scalar quantizers. The algorithm guarantees globally optimal solutions for conventional fixed-rate scalar quantizers and entropy-constrained scalar quantizers. For the other coding scenarios, the algorithm yields the best code among all codes that meet a given convexity constraint. In all cases, the algorithm run-time is polynomial in the size of the source Alphabet. The algorithm derivation arises from a demonstration of the connection between scalar quantization, histogram segmentation, and the shortest path problem in a certain directed acyclic graph.

  • quantization as histogram segmentation globally optimal scalar quantizer design in network systems
    Data Compression Conference, 2002
    Co-Authors: D Muresan, Michelle Effros
    Abstract:

    We propose a polynomial-time algorithm for optimal scalar quantizer design on Discrete-Alphabet sources. Special cases of the proposed approach yield optimal design algorithms for fixed-rate and entropy-constrained scalar quantizers, multi-resolution scalar quantizers, multiple description scalar quantizers, and Wyner-Ziv scalar quantizers. The algorithm guarantees globally optimal solutions for fixed-rate and entropy-constrained scalar quantizers and constrained optima for the other coding scenarios. We derive the algorithm by demonstrating the connection between scalar quantization, histogram segmentation, and the shortest path problem in a certain directed acyclic graph.

Chunshan Liu - One of the best experts on this subject based on the ideXlab platform.

  • precoding for the sparsely spread mc cdma downlink with Discrete Alphabet inputs
    arXiv: Information Theory, 2017
    Co-Authors: Chunshan Liu, Stephen V Hanly
    Abstract:

    Sparse signatures have been proposed for the CDMA uplink to reduce multi-user detection complexity, but they have not yet been fully exploited for its downlink counterpart. In this work, we propose a Multi-Carrier CDMA (MC-CDMA) downlink communication, where regular sparse signatures are deployed in the frequency domain. Taking the symbol detection point of view, we formulate a problem appropriate for the downlink with Discrete Alphabets as inputs. The solution to the problem provides a power-efficient precoding algorithm for the base station, subject to minimum symbol error probability (SEP) requirements at the mobile stations. In the algorithm, signature sparsity is shown to be crucial for reducing precoding complexity. Numerical results confirm system-load-dependent power reduction gain from the proposed precoding over the zero-forcing precoding and the regularized zero-forcing precoding with optimized regularization parameter under the same SEP targets. For a fixed system load, it is also demonstrated that sparse MC-CDMA with a proper choice of sparsity level attains almost the same power efficiency and link throughput as that of dense MC-CDMA yet with reduced precoding complexity, thanks to the sparse signatures.

  • precoding for the sparsely spread mc cdma downlink with Discrete Alphabet inputs
    IEEE Transactions on Vehicular Technology, 2017
    Co-Authors: Chunshan Liu, Stephen V Hanly
    Abstract:

    Sparse signatures have been proposed for the code-division multiple-access (CDMA) uplink to reduce multiuser detection complexity, but they have not yet been fully exploited for its downlink counterpart. In this paper, we propose multicarrier CDMA (MC-CDMA) downlink communication whereby regular sparse signatures are deployed in the frequency domain. Taking the symbol detection point of view, we formulate a problem appropriate for the downlink with Discrete Alphabets as inputs. The solution to the problem provides a power-efficient precoding algorithm for the base station (BS), subject to minimum symbol error probability (SEP) requirements at the mobile stations (MSs). In the algorithm, signature sparsity is shown to be crucial for reducing precoding complexity. Numerical results confirm system-load-dependent power reduction gain from the proposed precoding over the zero-forcing (ZF) precoding and the regularized ZF (RZF) precoding with optimized regularization parameter under the same SEP targets. For a fixed system load, it is also demonstrated that sparse MC-CDMA with a proper choice of sparsity level attains almost the same power efficiency and link throughput as that of dense MC-CDMA yet with reduced precoding complexity due to the sparse signatures.

Pirandola Stefano - One of the best experts on this subject based on the ideXlab platform.

  • Continuous-variable quantum cryptography with Discrete Alphabets: Composable security under collective Gaussian attacks
    'American Physical Society (APS)', 2021
    Co-Authors: Papanastasiou Panagiotis, Pirandola Stefano
    Abstract:

    We consider continuous-variable quantum key distribution with Discrete-Alphabet encodings. In particular, we study protocols where information is encoded in the phase of displaced coherent (or thermal) states, even though the results can be directly extended to any protocol based on finite constellations of displaced Gaussian states. In this setting, we provide a composable security analysis in the finite-size regime assuming the realistic but restrictive hypothesis of collective Gaussian attacks. Under this assumption, we can efficiently estimate the parameters of the channel via maximum likelihood estimators and bound the corresponding error in the final secret key rate.Comment: REVTeX. Comments are welcom

  • Quantum key distribution with phase-encoded coherent states : Asymptotic security analysis in thermal-loss channels
    'American Physical Society (APS)', 2018
    Co-Authors: Papanastasiou Panagiotis, Lupo Cosmo, Weedbrook Christian, Pirandola Stefano
    Abstract:

    We consider Discrete-Alphabet encoding schemes for coherent-state quantum key distribution. The sender encodes the letters of a finite-size Alphabet into coherent states whose amplitudes are symmetrically distributed on a circle centered in the origin of the phase space. We study the asymptotic performance of this phase-encoded coherent-state protocol in direct and reverse reconciliation assuming both loss and thermal noise in the communication channel. In particular, we show that using just four phase-shifted coherent states is sufficient for generating secret key rates of the order of $4 \times 10^{-3}$ bits per channel use at about 15 dB loss in the presence of realistic excess noise

  • Quantum key distribution with phase-encoded coherent states: Asymptotic security analysis in thermal-loss channels
    'American Physical Society (APS)', 2018
    Co-Authors: Papanastasiou Panagiotis, Lupo Cosmo, Weedbrook Christian, Pirandola Stefano
    Abstract:

    We consider Discrete-Alphabet encoding schemes for coherent-state quantum key distribution. The sender encodes the letters of a finite-size Alphabet into coherent states whose amplitudes are symmetrically distributed on a circle centered in the origin of the phase space. We study the asymptotic performance of this phase-encoded coherent-state protocol in direct and reverse reconciliation assuming both loss and thermal noise in the communication channel. In particular, we show that using just four phase-shifted coherent states is sufficient for generating secret key rates of the order of $4 \times 10^{-3}$ bits per channel use at about 15 dB loss in the presence of realistic excess noise.Comment: REVTeX. 8 pages. 7 figure

B Porat - One of the best experts on this subject based on the ideXlab platform.

  • blind identification of fir systems excited by Discrete Alphabet inputs
    IEEE Transactions on Signal Processing, 1993
    Co-Authors: D Yellin, B Porat
    Abstract:

    An algorithm for the identification of finite-impulse-response (FIR) system parameters from output measurements, for systems excited by Discrete-Alphabet inputs, is described. The approach taken is algebraic. It does not rely directly on the statistical properties of the measurements, but rather it essentially solves the nonlinear equations appearing in the problem by converting them to equivalent linear equations, using the Discrete-Alphabet property of the input signal. The proposed algorithm was tested by computer simulations and some of these simulations are illustrated. >