51,698 research outputs found
On Undetected Error Probability of Binary Matrix Ensembles
In this paper, an analysis of the undetected error probability of ensembles
of binary matrices is presented. The ensemble called the Bernoulli ensemble
whose members are considered as matrices generated from i.i.d. Bernoulli source
is mainly considered here. The main contributions of this work are (i)
derivation of the error exponent of the average undetected error probability
and (ii) closed form expressions for the variance of the undetected error
probability. It is shown that the behavior of the exponent for a sparse
ensemble is somewhat different from that for a dense ensemble. Furthermore, as
a byproduct of the proof of the variance formula, simple covariance formula of
the weight distribution is derived.Comment: 9 pages, a part of the paper was submitted to ISIT 200
Undetected error probability for data services in a terrestrial DAB single frequency network
DAB (Digital Audio Broadcasting) is the European successor of FM radio. Besides audio services, other services such as traffic information can be provided.\ud
An important parameter for data services is the probability of non-recognized or undetected errors in the system. To derive this probability, we propose a bound for the undetected error probability in CRC codes. In addition, results from measurements of a Single Frequency Network (SFN) in Amsterdam were used, where the University of Twente conducted a DAB field trial. The proposed error bound is compared with other error bounds from literature and the results are validated by simulations. Although the proposed bound is less tight than existing bounds, it requires no additional information about the CRC code such\ud
as the weight distribution. Moreover, the DAB standard has been extended last year by an Enhanced Packet Mode (EPM) which provides extra protection for data services. An undetected error probability for this mode is also derived. In a realistic user scenario of 10 million users, a 8 kbit/s EPM sub channel can be considered as a system without any undetected errors (Pud = 6 · 10−40). On\ud
the other hand, in a normal data sub channel, only 110 packets with undetected errors are received on average each year in the whole system (Pud = 5 · 10−13)
Reliable Transmission of Short Packets through Queues and Noisy Channels under Latency and Peak-Age Violation Guarantees
This work investigates the probability that the delay and the peak-age of
information exceed a desired threshold in a point-to-point communication system
with short information packets. The packets are generated according to a
stationary memoryless Bernoulli process, placed in a single-server queue and
then transmitted over a wireless channel. A variable-length stop-feedback
coding scheme---a general strategy that encompasses simple automatic repetition
request (ARQ) and more sophisticated hybrid ARQ techniques as special
cases---is used by the transmitter to convey the information packets to the
receiver. By leveraging finite-blocklength results, the delay violation and the
peak-age violation probabilities are characterized without resorting to
approximations based on large-deviation theory as in previous literature.
Numerical results illuminate the dependence of delay and peak-age violation
probability on system parameters such as the frame size and the undetected
error probability, and on the chosen packet-management policy. The guidelines
provided by our analysis are particularly useful for the design of low-latency
ultra-reliable communication systems.Comment: To appear in IEEE journal on selected areas of communication (IEEE
JSAC
Which Radial Velocity Exoplanets Have Undetected Outer Companions?
(Abridged) The observed radial velocity (RV) eccentricity distribution for
extrasolar planets in single-planet systems shows that a significant fraction
of planets are eccentric (). Here we investigate the effects on an RV
planet's eccentricity produced by undetected outer companions. We have carried
out Monte Carlo simulations of mock RV data to understand this effect and
predict its impact on the observed distribution. We first quantify the
statistical effect of undetected outer companions and show that this alone
cannot explain the observed distribution. We then modify the simulations to
consist of two populations, one of zero-eccentricity planets in double-planet
systems and the other of single planets drawn from an eccentric distribution.
Our simulations show that a good fit to the observed distribution is obtained
with 45% zero-eccentricity double-planets and 55% single eccentric planets.
Matching the observed distribution allows us to determine the probability that
a known RV planet's orbital eccentricity has been biased by an undetected
wide-separation companion. Our simulations show that moderately-eccentric
planets, with and , have a and probability, respectively, of having an undetected outer companion. We
encourage both high-contrast direct imaging and RV follow-up surveys of known
RV planets with moderate eccentricities to test our predictions and look for
previously undetected outer companions.Comment: 23 pages (12 text, 2 tables, 9 figures). Accepted to the
Astrophysical Journal 30 June 200
Improved error bounds for the erasure/list scheme: the binary and spherical cases
We derive improved bounds on the error and erasure rate for spherical codes
and for binary linear codes under Forney's erasure/list decoding scheme and
prove some related results.Comment: 18 pages, 3 figures. Submitted to IEEE Transactions on Informatin
Theory in May 2001, will appear in Oct. 2004 (tentative
Fault-tolerant sub-lithographic design with rollback recovery
Shrinking feature sizes and energy levels coupled with high clock rates and decreasing node capacitance lead us into a regime where transient errors in logic cannot be ignored. Consequently, several recent studies have focused on feed-forward spatial redundancy techniques to combat these high transient fault rates. To complement these studies, we analyze fine-grained rollback techniques and show that they can offer lower spatial redundancy factors with no significant impact on system performance for fault rates up to one fault per device per ten million cycles of operation (Pf = 10^-7) in systems with 10^12 susceptible devices. Further, we concretely demonstrate these claims on nanowire-based programmable logic arrays. Despite expensive rollback buffers and general-purpose, conservative analysis, we show the area overhead factor of our technique is roughly an order of magnitude lower than a gate level feed-forward redundancy scheme
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Assessing Asymmetric Fault-Tolerant Software
The most popular forms of fault tolerance against design faults use "asymmetric" architectures in which a "primary" part performs the computation and a "secondary" part is in charge of detecting errors and performing some kind of error processing and recovery. In contrast, the most studied forms of software fault tolerance are "symmetric" ones, e.g. N-version programming. The latter are often controversial, the former are not. We discuss how to assess the dependability gains achieved by these methods. Substantial difficulties have been shown to exist for symmetric schemes, but we show that the same difficulties affect asymmetric schemes. Indeed, the latter present somewhat subtler problems. In both cases, to predict the dependability of the fault-tolerant system it is not enough to know the dependability of the individual components. We extend to asymmetric architectures the style of probabilistic modeling that has been useful for describing the dependability of "symmetric" architectures, to highlight factors that complicate the assessment. In the light of these models, we finally discuss fault injection approaches to estimating coverage factors. We highlight the limits of what can be predicted and some useful research directions towards clarifying and extending the range of situations in which estimates of coverage of fault tolerance mechanisms can be trusted
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