Packet loss detection based on recent acknowledgement (RACK)

This disclosure describes techniques for packet loss detection in networks based on Recent ACKnowledgement (RACK). RACK technique uses the notion of time, instead of conventional approaches for packet loss detection such as packet or sequence counting. Packets are deemed lost if a packet that was sent sufficiently later has been cumulatively or selectively acknowledged. In example implementations, a sender that implements RACK technique records packet transmission times and infers losses using cumulative or selective acknowledgements

Sources of Dynamic Macroeconomic Fluctuations in Small Open Economies: The Case of Taiwan

Economic

A Study of Behavioral Intention for Mobile Commerce Using Technology Acceptance Model

Davis’s Technology Acceptance Model (TAM) suggests that perceived ease of use and perceived usefulness can predict user behavior and acceptance when using information technology. In this study we use it as a tool for evaluating the acceptance and usage for mobile commerce by employing data collected from 205 students selected proportionally from nine universities located at Taipei City. The results show that perceived ease of use and perceived usefulness are the fundamental determinants of user acceptance and have positive impact. They demonstrate positive impacts on attitude to use and behavioral intention to use. In addition, the attitude toward using m-commerce has a partial mediating effect on behavioral intention to use. Behavioral intention to use exerts a positive, though lesser, impact on actual use of m-commerce

Un aporte a la historia económica del Pacífico:: El Galeón de Manila de 1726

A complete register of merchants and merchandise associated with the Manila galleon trade in 1726, documentation both rare and difficult to locate, is subjected to scientific scrutiny. Findings help determine the type, origin, volume, and value of the goods that circulated in the Pacific during the modern age. This information clarifies and elucidates, thereby enhancing methodologically future research endeavours.Se propone poner a disposición de la comunidad científica el registro completo de mercancías y mercaderes del galeón de Manila de 1726, una información poco frecuente y de difícil localización. Con ella se pretende ayudar a explicar mejor el tipo, origen, volumen y valor de las mercancías que se intercambiaron en el comercio del océano Pacífico durante la Edad Moderna, pues se adelantan, además, algunas precisiones metodológicas que se creen necesarias para el análisis histórico de este tema

Model-based Network Congestion Control

Computer network congestion control algorithms control the sending rate for flows of data from sender network nodes to receiver network nodes. These algorithms attempt to utilize network bandwidth capacity efficiently, while keeping network data loss rates low, and allocating network capacity between different flows sharing the network in an approximately fair manner, or at least avoiding starvation of some flows. In addition, some congestion control algorithms attempt to keep network queues short, to reduce queuing delays and further reduce loss rates. This disclosure describes model-based congestion control, a technique that explicitly models the network conditions along the path(s) between senders and receivers. The algorithm updates the model using measurements obtained from the packets in the flow it is controlling. The algorithm uses those measurements as inputs to update the model and then uses that model to control its sending process. This model-based approach can allow the congestion control algorithm to achieve higher throughputs and/or lower delays and/or lower data packet loss rates than would be achievable by other techniques

Beyond socket options: making the Linux TCP stack truly extensible

The Transmission Control Protocol (TCP) is one of the most important protocols in today's Internet. Its specification and implementations have been refined for almost forty years. The Linux TCP stack is one of the most widely used TCP stacks given its utilisation on servers and Android smartphones and tablets. However, TCP and its implementations evolve very slowly. In this paper, we demonstrate how to leverage the eBPF virtual machine that is part of the recent versions of the Linux kernel to make the TCP stack easier to extend. We demonstrate a variety of use cases where the eBPF code is injected inside a running kernel to update or tune the TCP implementation. We first implement the TCP User Timeout Option. Then we propose a new option that enables a client to request a server to use a specific congestion control scheme. Our third extension is a TCP option that sets the initial congestion window. We then demonstrate how eBPF code can be used to tune the acknowledgment strategy.Comment: 9 pages, 8 figure

Compatibility of discrete conditional distributions with structural zeros

A general algorithm is provided for determining the compatibility among full conditionals of discrete random variables with structural zeros. The algorithm is scalable and it can be implemented in a fairly straightforward manner. A MATLAB program is included in the Appendix and therefore, it is now feasible to check the compatibility of multi-dimensional conditional distributions with constrained supports. Rather than the linear equations in the restricted domain of Arnold et al. (2002) [11] Tian et al. (2009) [16], the approach is odds-oriented and it is a discrete adaptation of the compatibility check of Besag (1994) [17]. The method naturally leads to the calculation of a compatible joint distribution or, in the absence of compatibility, a nearly compatible joint distribution. Besag's [5] factorization of a joint density in terms of conditional densities is used to justify the algorithm.Consecutive site Full conditionals Geometric average Incidence set Nearly compatible Odds Path

A simple algorithm for checking compatibility among discrete conditional distributions

A distribution is said to be conditionally specified when only its conditional distributions are known or available. The very first issue is always compatibility: does there exist a joint distribution capable of reproducing all of the conditional distributions? We review five methods-mostly for two or three variables-published since 2002, and we conclude that these methods are either mathematically too involved and/or are too difficult (and in many cases impossible) to generalize to a high dimension. The purpose of this paper is to propose a general algorithm that can efficiently verify compatibility in a straightforward fashion. Our method is intuitively simple and general enough to deal with any full-conditional specifications. Furthermore, we illustrate the phenomenon that two theoretically equivalent conditional models can be different in terms of compatibilities, or can result in different joint distributions. The implications of this phenomenon are also discussed.Connected site Consecutive site Full conditionals Support Odds Path

Canonical representation of conditionally specified multivariate discrete distributions

Most work on conditionally specified distributions has focused on approaches that operate on the probability space, and the constraints on the probability space often make the study of their properties challenging. We propose decomposing both the joint and conditional discrete distributions into characterizing sets of canonical interactions, and we prove that certain interactions of a joint distribution are shared with its conditional distributions. This invariance opens the door for checking the compatibility between conditional distributions involving the same set of variables. We formulate necessary and sufficient conditions for the existence and uniqueness of discrete conditional models, and we show how a joint distribution can be easily computed from the pool of interactions collected from the conditional distributions. Hence, the methods can be used to calculate the exact distribution of a Gibbs sampler. Furthermore, issues such as how near compatibility can be reconciled are also discussed. Using mixed parametrization, we show that the proposed approach is based on the canonical parameters, while the conventional approaches are based on the mean parameters. Our advantage is partly due to the invariance that holds only for the canonical parameters.primary, 62E10, 62E15 secondary, 62E17, 62H05 Canonical parameter Characterizing set of interactions Compatibility check Exponential family Near-compatible Pseudo-Gibbs sampler