Portion Of Message Research Articles

Max–Min Fairness Beamforming With Rate-Splitting Multiple Access: Optimization Without a Toolbox

We propose a max-min fairness (MMF) design method in a multi-antenna downlink network, where rate-splitting multiple access (RSMA) is adopted. A main aim in the considered MMF problem is providing uniformly good rates to users, by carefully controlling the rate of each private and common message, respectively. Solving this problem is challenging since multiple optimization variables, i.e., beamforming vectors and common message portions, are intricately intertwined in a non-tractable objective function. To resolve these obstacles, we first split a whole problem into two stages. In the first stage, we identify beamforming vectors given common message portion by exploiting the LogSumExp (LSE) approximation technique and the novel generalized power iteration (GPI) framework. In the second stage, we determine common message portions under fixed beamforming vectors. Iterating these two stages, we jointly design beamforming vectors and common message portion accordingly. Via simulations, we demonstrate that our method outperforms existing other frameworks in terms of the minimum rate, while requiring extremely small computational complexity.

Types (Disinformation)

Types (Disinformation)

Evaluating Dynamic Approaches to Key (Re-)Establishment in Wireless Sensor Networks

Wireless sensor networks with a large number of cheap low-power interconnected devices bring up challenging tasks when considering the security of their communications. In our previous work, we presented two approaches for the design of dynamic protocols for link key (re-)establishment in ad hoc networks, using two elements studied earlier—secrecy amplification and key extraction from radio channel fading. The goal of this article is to provide a unified approach to the design of these protocols, together with their experimental verification, in a real network with various settings. The overall results of our experiments show that our dynamic combination of secrecy amplification and key extraction from radio channel fading saves a significant portion of messages with corresponding energy expenditure and can adapt to a much wider scale of environments when compared to previous solutions based on the exploitation of the individual elements of secrecy amplification and key extraction from radio channel fading.

Cued Speech Transliteration: Effects of Speaking Rate and Lag Time on Production Accuracy.

Many deaf and hard-of-hearing children rely on interpreters to access classroom communication. Although the exact level of access provided by interpreters in these settings is unknown, it is likely to depend heavily on interpreter accuracy (portion of message correctly produced by the interpreter) and the factors that govern interpreter accuracy. In this study, the accuracy of 12 Cued Speech (CS) transliterators with varying degrees of experience was examined at three different speaking rates (slow, normal, fast). Accuracy was measured with a high-resolution, objective metric in order to facilitate quantitative analyses of the effect of each factor on accuracy. Results showed that speaking rate had a large negative effect on accuracy, caused primarily by an increase in omitted cues, whereas the effect of lag time on accuracy, also negative, was quite small and explained just 3% of the variance. Increased experience level was generally associated with increased accuracy; however, high levels of experience did not guarantee high levels of accuracy. Finally, the overall accuracy of the 12 transliterators, 54% on average across all three factors, was low enough to raise serious concerns about the quality of CS transliteration services that (at least some) children receive in educational settings.

Peptide/benzodiazepine hybrids as ligands of CCK(A) and CCK(B) receptors.

The (neuro)hormones gastrin and cholecystokinin (CCK) share a common C-terminal tetrapeptide amide sequence that has been recognized as the message portion while the N-terminal extensions are responsible for the CCK(A) and CCK(B) receptor subtype selectivity and avidity. 1,4-Benzodiazepine derivatives are potent and selective antagonists of these receptors, and according to comparative molecular field analysis, the structures of these nonpeptidic compounds could well mimic the message sequence of the peptide agonists at least in terms of spatial array of the aromatic residues. Docking of a larger series of low molecular weight nonpeptide antagonists to a homology modeling derived CCK(B) receptor structure revealed a consensus binding mode that is further validated by data from site-directed mutagenesis studies of the receptors. Whether this putative binding pocket of the nonpeptide antagonists is identical to that of the message portion of the peptide agonists, or whether it is distinct and spatially separated, or overlapping, but with distinct interaction sites, is still object of debate. Using a 1,4-benzodiazepine core amino-functionalized at the C3 position, related tryptophanyl derivatives were synthesized as mimics of the tetrapeptide and subsequently extended N-terminally with gastrin and CCK address sequences. All hybrid constructs were recognized as antagonists by the CCK(A) and CCK(B) receptors, but their address portions were incapable of enhancing in significant manner selectivity and avidity. Consequently, the binding of the peptide/benzodiazepine hybrids has to be dictated mainly by the benzodiazepine moiety, which apparently prevents optimal interactions of the address peptides with extracellular receptor subdomains. These findings would strongly support the view of distinct binding sites for the message portion of the peptide agonists and the benzodiazepine-based nonpeptide antagonists.

Threading electronic mail: A preliminary study

Tools for processing email and other electronic messages should be able to recognize and manipulate threads, that is, conversations among two or more people carried out by exchange of messages. While user clients typically insert in messages structural information useful for recovering threads, inconsistencies between clients, loose standards, creative user behavior, and the subjective nature of conversation make threading systems based on structural information only partially successful. We propose that this situation is unlikely to change, and that threading of electronic messages be treated as a language processing task. Preliminary experiments show that a significant level of threading effectiveness can be achieved by applying standard text matching methods from information retrieval to the textual portions of messages.

Methods and apparatus for non-simultaneous transmittal and storage of voice message and digital text for image

Apparatus and methods are provided for non-simultaneously creating and storing in electronic format a composite voice/data message having a recorded voice message portion and a facsimile transmittal portion. The method provides for creating a voice message and sending a time-wise separated facsimile transmittal to a voice message/data storage system, and then associating the separate voice message and facsimile transmittal portions to form a composite voice/data message. The methods include a message identification scheme wherein a message identification number is assigned to the first-received message portion, and the caller is prompted to provide that message identification number in connection with the later-received message portion. Apparatus to accomplish these methods steps is also provided.

Two distinct destabilizing elements in the c-fos message trigger deadenylation as a first step in rapid mRNA decay.

The mechanisms by which c-fos mRNA is targeted for decay have been examined. Rapid removal of the poly(A) tail occurs before the transcribed portion of the c-fos message is degraded. Identification of the determinants that mediate c-fos message deadenylation reveals that they coincide directly with previously characterized determinants of c-fos mRNA instability, one in the protein-coding region and the other an AU-rich element (ARE) in the 3'-untranslated region. Insertion of either of these c-fos instability elements into the stable beta-globin message confers the property of rapid deadenylation. Mutation of the ARE indicates that this sequence controls two steps in the process of c-fos mRNA degradation: removal of the poly(A) tail, which does not require intact AUUUA pentanucleotides within the ARE, and subsequent degradation of the transcribed portion of the message, which appears to be dependent on the AUUUA pentanucleotides. These results indicate that structurally distinct instability determinants within the transcribed portion of labile messages can function by promoting rapid removal of the poly(A) tail as a first step in the decay process.

Facsimile transmission via HF radio

The authors examine the feasibility of transmitting facsimile (FAX) over radio voice-channels using existing machines and existing radio installations. CCITT Groups 1, 2, and 3 FAX were tested on simulated high-frequency (HF) channels using the US government's HF simulator at Ft. Monmouth, NJ. Tests included both the premessage exchange and the message portion of the FAX transmission. Test results show that the FAX integral wire-line model used for Group 3 operation does not work well on realistic, long-haul, HF channels even at the minimum fallback rate of 2400 b/s. Group 2 FAX also fails for most of the cases simulated. Group 1 FAX produces documents on most simulated channels although the quality of the document degrades as the impairments become severe. The degraded documents, however, are usable in most cases. >

Supporting systolic and memory communication in iWarp

iWarp is a parallel architecture developed jointly by Carnegie Mellon University and Intel Corporation. The iWarp communication system supports two widely used interprocessor communication styles: memory communication and systolic communication . This paper describes the rationale, architecture, and implementation for the iWarp communication system. The sending or receiving processor of a message can perform either memory or systolic communication. In memory communication, the entire message is buffered in the local memory of the processor before it is transmitted or after it is received. Therefore communication begins or terminates at the local memory. For conventional message passing methods, both sending and receiving processors use memory communication. In systolic communication, individual data items are transferred as they are produced, or are used as they are received, by the program running at the processor. Memory communication is flexible and well suited for general computing; whereas systolic communication is efficient and well suited for speed critical applications. A major achievement of the iWarp effort is the derivation of a common design to satisfy the requirements of both systolic and memory communication styles. This is made possible by two important innovations in communication: (1) program access to communication and (2) logical channels. The former allows programs to access data as they are transmitted and to redirect portions of messages to different destinations efficiently. The latter increases the connectivity between the processors and guarantees communication bandwidth for classes of messages. These innovations have provided a focus for the iWarp architecture. The result is a communication system that provides a total bandwidth of 320 MBytes/sec and that is integrated on a single VLSI component with a 20 MFLOPS plus 20 MIPS long instruction word computation engine.

Application of surface-acoustic-wave technology to burst-format spread-spectrum communications

A hybrid direct-sequence/frequency-hopping spread-spectrum communication modem for burst format transmission of digital data has been developed. A burst consists of a short synchronisation preamble and the data packet. Data modulation is accomplished by assignment of pairs of pseudonoise sequences with low crosscorrelation for message ones and zeros. The spreading code chip pattern is changed from bit to bit in both the preamble and the message portion of a burst. Receiver signal processing is based on the application of surface-acoustic-wave (SAW) elastic convolvers to programmable matched filtering. The performance of the system in an additive white Gaussian noise channel is analysed, measures of performance being the probability of burst loss and the bit error probability in the case of ideal synchronisation. Evaluations for a particular design are presented, and some experimental results obtained with a test system are shown for comparison.

Transmitted-reference techniques for random or unknown channels

In this paper, a particular approach to the problem of communicating in certain random or unknown channels is considered. A particular set of signals is chosen, each member of which is partitioned into a known reference or sounding signal and a message signal. The channel is assumed to be linear, and is divided into a multiplicative and an additive portion. The multiplicative portion is assumed to have the same response to both message and reference components, while the additive noises associated with these components are assumed to be independent. The channel outputs and the additive noises are further assumed to be Gaussian. Under these circumstances, the optimum receiver is shown to cross-correlate the message portion of the received signal with a filtered version of the posterior mean of the channel output, which is merely a filtered combination of the prior mean and the perturbed reference signal. This is an interesting extension of the optimum receiver for known signals in additive Gaussian noise. Several special cases are considered which yield additional insight into the operation of the optimum receiver.