Circuits, Systems and Computers, 1977. Conference Record. 1977 11th Asilomar Conference on

Publisher: Systems & Computers Asilomar Conference on Signals; Naval Postgraduate School (U.S.); IEEE Acoustics, Speech, and Signal Processing Society; Institute of Electrical and Electronics Engineers

Description

  • Impact factor
    0.00
  • 5-year impact
    0.00
  • Cited half-life
    0.00
  • Immediacy index
    0.00
  • Eigenfactor
    0.00
  • Article influence
    0.00
  • Website
    Conference Record - Asilomar Conference on Signals, Systems and Computers website
  • Other titles
    Conference record - Asilomar Conference on Signals, Systems, & Computers, Asilomar Conference on Signals, Systems, and Computers, Conference record of the ... Asilomar Conference on Signals, Systems & Computers
  • ISSN
    1058-6393
  • OCLC
    16620517
  • Material type
    Conference publication, Internet resource
  • Document type
    Journal / Magazine / Newspaper, Internet Resource

Publications in this journal

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Low-complexity precoding {algorithms} are proposed in this work to reduce the computational complexity and improve the performance of regularized block diagonalization (RBD) {based} precoding {schemes} for large multi-user {MIMO} (MU-MIMO) systems. The proposed algorithms are based on a channel inversion technique, QR decompositions{,} and lattice reductions to decouple the MU-MIMO channel into equivalent SU-MIMO channels. Simulation results show that the proposed precoding algorithms can achieve almost the same sum-rate performance as RBD precoding, substantial bit error rate (BER) performance gains{,} and a simplified receiver structure, while requiring a lower complexity.
    Circuits, Systems and Computers, 1977. Conference Record. 1977 11th Asilomar Conference on 04/2013;
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: In this paper we investigate stopping criteria for iterative decoding from a mutual information perspective. We introduce new iteration stopping rules based on an approximation of the mutual information between encoded bits and decoder soft output. The first type stopping rule sets a threshold value directly on the approximated mutual information for terminating decoding. The threshold can be adjusted according to the expected bit error rate. The second one adopts a strategy similar to that of the well known cross-entropy stopping rule by applying a fixed threshold on the ratio of a simple metric obtained after each iteration over that of the first iteration. Compared with several well known stopping rules, the new methods achieve higher efficiency.
    Circuits, Systems and Computers, 1977. Conference Record. 1977 11th Asilomar Conference on 02/2013;
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: This work tackles the problem of energy-efficient distributed power control in wireless networks with a large number of transmitters. The problem is modeled by a dynamic game. Each transmitter-receiver communication is characterized by a state given by the available energy and/or the individual channel state and whose evolution is governed by certain dynamics. Since equilibrium analysis in such a (stochastic) game is generally difficult and even impossible, the problem is approximated by exploiting the large system assumption. Under an appropriate exchangeability assumption, the corresponding mean field game is well defined and studied in detail for special cases. The main contribution of this work is to show how mean field games can be applied to the problem under investigation and provide illustrative numerical results. Our results indicate that this approach can lead to significant gains in terms of energy-efficiency at the resulting equilibrium.
    Circuits, Systems and Computers, 1977. Conference Record. 1977 11th Asilomar Conference on 01/2013;
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: A fully-asynchronous network with one target sensor and a few anchors (nodes with known locations) is considered. Localization and synchronization are traditionally treated as two separate problems. In this paper, localization and synchronization is studied under a unified framework. We present a new model in which time-stamps obtained either via two-way communication between the nodes or with a broadcast based protocol can be used in a simple estimator based on least-squares (LS) to jointly estimate the position of the target node as well as all the unknown clock-skews and clock-offsets. The Cram\'er-Rao lower bound (CRLB) is derived for the considered problem and is used as a benchmark to analyze the performance of the proposed estimator.
    Circuits, Systems and Computers, 1977. Conference Record. 1977 11th Asilomar Conference on 01/2013;
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: In cellular networks, admission control and beamforming optimization are intertwined problems. While beamforming optimization aims at satisfying users' quality-of-service (QoS) requirements or improving the QoS levels, admission control looks at how a subset of users should be selected so that the beamforming optimization problem can yield a reasonable solution in terms of the QoS levels provided. However, in order to simplify the design, the two problems are usually seen as separate problems. This paper considers joint admission control and beamforming (JACoB) under a coordinated multicell MISO downlink scenario. We formulate JACoB as a user number maximization problem, where selected users are guaranteed to receive the QoS levels they requested. The formulated problem is combinatorial and hard, and we derive a convex approximation to the problem. A merit of our convex approximation formulation is that it can be easily decomposed for per-base-station decentralized optimization, namely, via block coordinate decent. The efficacy of the proposed decentralized method is demonstrated by simulation results.
    Circuits, Systems and Computers, 1977. Conference Record. 1977 11th Asilomar Conference on 11/2012;
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: A sensing policy for the restless multi-armed bandit problem with stationary but unknown reward distributions is proposed. The work is presented in the context of cognitive radios in which the bandit problem arises when deciding which parts of the spectrum to sense and exploit. It is shown that the proposed policy attains asymptotically logarithmic weak regret rate when the rewards are bounded independent and identically distributed or finite state Markovian. Simulation results verifying uniformly logarithmic weak regret are also presented. The proposed policy is a centrally coordinated index policy, in which the index of a frequency band is comprised of a sample mean term and a confidence term. The sample mean term promotes spectrum exploitation whereas the confidence term encourages exploration. The confidence term is designed such that the time interval between consecutive sensing instances of any suboptimal band grows exponentially. This exponential growth between suboptimal sensing time instances leads to logarithmically growing weak regret. Simulation results demonstrate that the proposed policy performs better than other similar methods in the literature.
    Circuits, Systems and Computers, 1977. Conference Record. 1977 11th Asilomar Conference on 11/2012;
  • [Show abstract] [Hide abstract]
    ABSTRACT: Suppression of co-channel interference in the receiver of a MIMO-OFDM system is considered. The interference and noise spatial covariance matrix measured on the pilot subcarriers is used in data detection and channel estimation. The impact of the accuracy of the matrix decomposition on the structure of the covariance matrix is studied. An algorithm to adapt the accuracy of the matrix decomposition and the use of interference suppression is proposed. The complexity and performance of eigenspace tracking is also considered. The different interference mitigation methods are implemented and the performance-complexity tradeoffs are found out. Eigenspace tracking performs well in some scenarios but the complexity and memory requirements are higher than those of the unstructured model or the adaptive algorithm. A good performance is achieved with the adaptive algorithm in all interference scenarios and the power consumption of the receiver can be reduced by adapting the interference mitigation.
    Asilomar Conference on Signals, Systems and Computers; 11/2012
  • [Show abstract] [Hide abstract]
    ABSTRACT: The use of decision directed (DD) channel estimation in a multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) downlink receiver is studied in this paper. The 3GPP long term evolution (LTE) based pilot structure is used as a benchmark. The space-alternating generalized expectation-maximization (SAGE) algorithm is used to improve the performance from that of the pilot symbol based least-squares (LS) channel estimator. The DD channel estimation improves the performance with high user velocities, where the pilot symbol density is not sufficient. It can also be used to reduce the pilot overhead without any performance degradation. Minimum mean square error (MMSE) filtering can also be used in estimating the channel in between pilot symbols. The pilot based LS, MMSE and the SAGE channel estimators are implemented and the performance-complexity trade-offs are studied.
    Asilomar Conference on Signals, Systems and Computers; 11/2012
  • [Show abstract] [Hide abstract]
    ABSTRACT: Compressive sampling is a popular approach to relax the rate requirement on the analog-to-digital converters and to perfectly reconstruct wideband sparse signals sampled below the Nyquist rate. However, there are some applications, such as spectrum sensing for cognitive radio, that demand only power spectrum recovery. For wide-sense stationary signals, power spectrum reconstruction based on samples produced by a sub-Nyquist rate sampling device is possible even without any sparsity constraints on the power spectrum. In this paper, we examine an extension of our proposed power spectrum reconstruction approach to the case when multiple sensors cooperatively sense the power spectrum of the received signals. In cognitive radio networks, this cooperation is advantageous in terms of the channel diversity gain as well as a possible sampling rate reduction per receiver. In this work, we mainly focus on how far this cooperative scheme promotes the sampling rate reduction at each sensor and assume that the channel state information is available. We concentrate on a centralized network where each sensor forwards the collected measurements to a fusion centre, which then computes the cross-spectra between the measurements obtained by different sensors. We can express these cross-spectra of the measurements as a linear function of the power spectrum of the original signal and attempt to solve it using a least-squares algorithm.
    Signals, Systems and Computers (ASILOMAR), 2012 Conference Record of the Forty Sixth Asilomar Conference on; 11/2012
  • [Show abstract] [Hide abstract]
    ABSTRACT: In this paper, we analyze the effect of quantization on a multiuser MIMO OFDMA downlink employing heterogeneous partial feedback design method, which adapts users' feedback resources to their frequency domain channel statistics. This adaptive feedback design is investigated for the best-M partial feedback scheme, and the closed form expression for the sum rate under finite-rate quantization is derived for a system employing transmit antenna selection/maximum ratio combining (TAS/MRC) spatial diversity scheme under the generalized Nakagami fading channels. The sum rate provides a basis for determining the different quantization levels of an optimal non-uniform quantizer. For complexity reasons, a low complexity near optimal quantization strategy is proposed which employs uniform quantization with optimized intervals.
    Proc. Asilomar Conference on Signals, Systems, and Computers; 11/2012