Polar Coded HARQ Scheme with Chase Combining

A hybrid automatic repeat request scheme with Chase combing (HARQ-CC) of polar codes is proposed. The existing analysis tools of the underlying rate-compatible punctured polar (RCPP) codes for additive white Gaussian noise (AWGN) channels are extended to Rayleigh fading channels. Then, an approximation bound of the throughput efficiency for the polar coded HARQ-CC scheme is derived. Utilizing this bound, the parameter configurations of the proposed scheme can be optimized. Simulation results show that, the proposed HARQ-CC scheme under a low-complexity SC decoding is only about $1.0$dB away from the existing schemes with incremental redundancy (\mbox{HARQ-IR}). Compared with the polar coded \mbox{HARQ-IR} scheme, the proposed HARQ-CC scheme requires less retransmissions and has the advantage of good compatibility to other communication techniques.Comment: Accepted by WCNC 201

Rcpp: Seamless R and C++ Integration

The Rcpp package simplifies integrating C++ code with R. It provides a consistent C++ class hierarchy that maps various types of R objects (vectors, matrices, functions, environments, . . . ) to dedicated C++ classes. Object interchange between R and C++ is managed by simple, flexible and extensible concepts which include broad support for C++ Standard Template Library idioms. C++ code can both be compiled, linked and loaded on the fly, or added via packages. Flexible error and exception code handling is provided. Rcpp substantially lowers the barrier for programmers wanting to combine C++ code with R.

Equity, Options and Efficiency in the Presence of Moral Hazard

This paper provides a general equilibrium analysis of an economy with production under uncertainty in which the firms' capital (ownership) structure creates a moral hazard problem for their managers. The paper studies the concept of an equilibrium with rational, competitive price perceptions (RCPP) in which investors correctly anticipate the optimal effort of entrepreneurs by observing their financial decisions, and entrepreneurs are aware that investors use their financial decisions as signals. The competitive element in the equilibrium valuation of firms comes from the fact that entrepreneurs cannot affect the market price of risks. It is shown that under appropriate spanning assumptions an RCPP is constrained Pareto optimal. Furthermore, if sufficiently many options are traded, then full optimality can be obtained despite the moral hazard problem: options serve both to increase the span of the market and to provide incentives for entrepreneurs.

R friendly multi-threading in C++

Calling multi-threaded C++ code from R has its perils. Since the R interpreter is single-threaded, one must not check for user interruptions or print to the R console from multiple threads. One can, however, synchronize with R from the main thread. The R package RcppThread (current version 0.5.3) contains a header only C++ library for thread safe communication with R that exploits this fact. It includes C++ classes for threads, a thread pool, and parallel loops that routinely synchronize with R. This article explains the package's functionality and gives examples of its usage. The synchronization mechanism may also apply to other threading frameworks. Benchmarks suggest that, although synchronization causes overhead, the parallel abstractions of RcppThread are competitive with other popular libraries in typical scenarios encountered in statistical computing

The Resonant Dynamics of Speech Perception: Interword Integration and Duration-Dependent Backward Effects

How do listeners integrate temporally distributed phonemic information into coherent representations of syllables and words? During fluent speech perception, variations in the durations of speech sounds and silent pauses can produce different pereeived groupings. For exarnple, increasing the silence interval between the words "gray chip" may result in the percept "great chip", whereas increasing the duration of fricative noise in "chip" may alter the percept to "great ship" (Repp et al., 1978). The ARTWORD neural model quantitatively simulates such context-sensitive speech data. In AHTWORD, sequential activation and storage of phonemic items in working memory provides bottom-up input to unitized representations, or list chunks, that group together sequences of items of variable length. The list chunks compete with each other as they dynamically integrate this bottom-up information. The winning groupings feed back to provide top-down supportto their phonemic items. Feedback establishes a resonance which temporarily boosts the activation levels of selected items and chunks, thereby creating an emergent conscious percept. Because the resonance evolves more slowly than wotking memory activation, it can be influenced by information presented after relatively long intervening silence intervals. The same phonemic input can hereby yield different groupings depending on its arrival time. Processes of resonant transfer and competitive teaming help determine which groupings win the competition. Habituating levels of neurotransmitter along the pathways that sustain the resonant feedback lead to a resonant collapsee that permits the formation of subsequent. resonances.Air Force Office of Scientific Research (F49620-92-J-0225); Defense Advanced Research projects Agency and Office of Naval Research (N00014-95-1-0409); National Science Foundation (IRI-97-20333); Office of Naval Research (N00014-92-J-1309, NOOO14-95-1-0657