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Results 1 - 10
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2,708
Estimating standard errors in finance panel data sets: comparing approaches.
- Review of Financial Studies
, 2009
"... Abstract In both corporate finance and asset pricing empirical work, researchers are often confronted with panel data. In these data sets, the residuals may be correlated across firms and across time, and OLS standard errors can be biased. Historically, the two literatures have used different solut ..."
Abstract
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Cited by 890 (7 self)
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solutions to this problem. Corporate finance has relied on clustered standard errors, while asset pricing has used the Fama-MacBeth procedure to estimate standard errors. This paper examines the different methods used in the literature and explains when the different methods yield the same (and correct
Monotone Complexity
, 1990
"... We give a general complexity classification scheme for monotone computation, including monotone space-bounded and Turing machine models not previously considered. We propose monotone complexity classes including mAC i , mNC i , mLOGCFL, mBWBP , mL, mNL, mP , mBPP and mNP . We define a simple ..."
Abstract
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Cited by 2825 (11 self)
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We give a general complexity classification scheme for monotone computation, including monotone space-bounded and Turing machine models not previously considered. We propose monotone complexity classes including mAC i , mNC i , mLOGCFL, mBWBP , mL, mNL, mP , mBPP and mNP . We define a
Multi-Channel MAC for Ad Hoc Networks: Handling Multi-Channel Hidden Terminals Using a Single Transceiver
- In ACM MobiHoc
, 2004
"... This paper proposes a medium access control (MAC) protocol for ad hoc wireless networks that utilizes multiple channels dynamically to improve performance. The IEEE 802.11 standard allows for the use of multiple channels available at the physical layer, but its MAC protocol is designed only for a si ..."
Abstract
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Cited by 431 (6 self)
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single channel. A single-channel MAC protocol does not work well in a multi-channel environment, because of the multi-channel hidden terminal problem. Our proposed protocol enables hosts to utilize multiple channels by switching channels dynamically, thus increasing network throughput. The protocol
Loopy belief propagation for approximate inference: An empirical study. In:
- Proceedings of Uncertainty in AI,
, 1999
"... Abstract Recently, researchers have demonstrated that "loopy belief propagation" -the use of Pearl's polytree algorithm in a Bayesian network with loops -can perform well in the context of error-correcting codes. The most dramatic instance of this is the near Shannon-limit performanc ..."
Abstract
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Cited by 676 (15 self)
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propagation converges, it gives a surprisingly good ap proximation to the correct marginals. Since the dis tinction between convergence and oscillation is easy to make after a small number of iterations, this may sug gest a way of checking whether loopy propagation is appropriate for a given problem. Acknowl
X-mac: A short preamble mac protocol for duty-cycled wireless sensor networks
- in SenSys
, 2006
"... In this paper we present X-MAC, a low power MAC protocol for wireless sensor networks (WSNs). Standard MAC protocols developed for duty-cycled WSNs such as B-MAC, which is the default MAC protocol for TinyOS, employ an extended preamble and preamble sampling. While this “low power listening ” approa ..."
Abstract
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Cited by 360 (0 self)
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” approach is simple, asynchronous, and energy-efficient, the long preamble introduces excess latency at each hop, is suboptimal in terms of energy consumption, and suffers from excess energy consumption at nontarget receivers. X-MAC proposes solutions to each of these problems by employing a shortened
Implementation issues in spectrum sensing for cognitive radios
- in Proc. the 38th. Asilomar Conference on Signals, Systems, and Computers
, 2004
"... Abstract- There are new system implementation challenges involved in the design of cognitive radios, which have both the ability to sense the spectral environment and the flexibility to adapt transmission parameters to maximize system capacity while co-existing with legacy wireless networks. The cri ..."
Abstract
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Cited by 440 (7 self)
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. The critical design problem is the need to process multi-gigahertz wide bandwidth and reliably detect presence of primary users. This places severe requirements on sensitivity, linearity, and dynamic range of the circuitry in the RF front-end. To improve radio sensitivity of the sensing function through
Deafness: A MAC Problem in Ad Hoc Networks when using Directional Antennas
"... This paper addresses deafness – a problem that appears when MAC protocols are designed using directional antennas. Briefly, deafness is caused when a transmitter fails to communicate to its intended receiver, because the receiver is beamformed towards a direction away from the transmitter. Existing ..."
Abstract
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Cited by 105 (12 self)
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This paper addresses deafness – a problem that appears when MAC protocols are designed using directional antennas. Briefly, deafness is caused when a transmitter fails to communicate to its intended receiver, because the receiver is beamformed towards a direction away from the transmitter
Duality, achievable rates, and sum-rate capacity of Gaussian MIMO broadcast channels
- IEEE TRANS. INFORM. THEORY
, 2003
"... We consider a multiuser multiple-input multiple-output (MIMO) Gaussian broadcast channel (BC), where the transmitter and receivers have multiple antennas. Since the MIMO BC is in general a nondegraded BC, its capacity region remains an unsolved problem. In this paper, we establish a duality between ..."
Abstract
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Cited by 339 (21 self)
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We consider a multiuser multiple-input multiple-output (MIMO) Gaussian broadcast channel (BC), where the transmitter and receivers have multiple antennas. Since the MIMO BC is in general a nondegraded BC, its capacity region remains an unsolved problem. In this paper, we establish a duality
An Adaptive Energy-Efficient and Low-Latency MAC for Data Gathering
, 2004
"... In many sensor network applications the major traffic pattern consists of data collected from several source nodes to a sink through a unidirectional tree. In this paper, we propose DMAC, an energy efficient and low latency MAC that is designed and optimized for such data gathering trees in wireless ..."
Abstract
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Cited by 240 (7 self)
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in wireless sensor networks. We first show that previously proposed MAC protocols for sensor networks that utilize activation/sleep duty cycles suffer from a data forwarding interruption problem, whereby not all nodes on a multihop path to the sink are notified of data delivery in progress, resulting
Dual Busy Tone Multiple Access (DBTMA) - A Multiple Access Control Scheme for Ad Hoc Networks
- IEEE Transactions on Communications
, 2002
"... In ad hoc networks, the hidden- and the exposed-terminal problems can severely reduce the network capacity on the MAC layer. To address these problems, the ready-to-send and clear-to-send (RTS/CTS) dialogue has been proposed in the literature. However, MAC schemes using only the RTS/CTS dialogue can ..."
Abstract
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Cited by 302 (13 self)
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In ad hoc networks, the hidden- and the exposed-terminal problems can severely reduce the network capacity on the MAC layer. To address these problems, the ready-to-send and clear-to-send (RTS/CTS) dialogue has been proposed in the literature. However, MAC schemes using only the RTS/CTS dialogue
Results 1 - 10
of
2,708
