418 research outputs found
Cross-layer performance control of wireless channels using active local profiles
To optimize performance of applications running over wireless channels state-of-the-art wireless access technologies incorporate a number of channel adaptation mechanisms. While these mechanisms are expected to operate jointly providing the best possible performance for current wireless channel and traffic conditions, their joint effect is often difficult to predict. To control functionality of various channel adaptation mechanisms a new cross-layer performance optimization system is sought. This system should be responsible for exchange of control information between different layers and further optimization of wireless channel performance. In this paper design of the cross-layer performance control system for wireless access technologies with dynamic adaptation of protocol parameters at different layers of the protocol stack is proposed. Functionalities of components of the system are isolated and described in detail. To determine the range of protocol parameters providing the best possible performance for a wide range of channel and arrival statistics the proposed system is analytically analyzed. Particularly, probability distribution functions of the number of lost frames and delay of a frame as functions of first- and second-order wireless channel and arrival statistics, automatic repeat request, forward error correction functionality, protocol data unit size at different layers are derived. Numerical examples illustrating performance of the whole system and its elements are provided. Obtained results demonstrate that the proposed system provide significant performance gains compared to static configuration of protocols
An Accurate Approximation of Resource Request Distributions in Millimeter Wave 3GPP New Radio Systems
The recently standardized millimeter wave-based 3GPP New Radio technology is
expected to become an enabler for both enhanced Mobile Broadband (eMBB) and
ultra-reliable low latency communication (URLLC) services specified to future
5G systems. One of the first steps in mathematical modeling of such systems is
the characterization of the session resource request probability mass function
(pmf) as a function of the channel conditions, cell size, application demands,
user location and system parameters including modulation and coding schemes
employed at the air interface. Unfortunately, this pmf cannot be expressed via
elementary functions. In this paper, we develop an accurate approximation of
the sought pmf. First, we show that Normal distribution provides a fairly
accurate approximation to the cumulative distribution function (CDF) of the
signal-to-noise ratio for communication systems operating in the millimeter
frequency band, further allowing evaluating the resource request pmf via error
function. We also investigate the impact of shadow fading on the resource
request pmf.Comment: The 19th International Conference on Next Generation Wired/Wireless
Networks and Systems (New2An 2019
Caching-Aided Collaborative D2D Operation for Predictive Data Dissemination in Industrial IoT
Industrial automation deployments constitute challenging environments where
moving IoT machines may produce high-definition video and other heavy sensor
data during surveying and inspection operations. Transporting massive contents
to the edge network infrastructure and then eventually to the remote human
operator requires reliable and high-rate radio links supported by intelligent
data caching and delivery mechanisms. In this work, we address the challenges
of contents dissemination in characteristic factory automation scenarios by
proposing to engage moving industrial machines as device-to-device (D2D)
caching helpers. With the goal to improve reliability of high-rate
millimeter-wave (mmWave) data connections, we introduce the alternative
contents dissemination modes and then construct a novel mobility-aware
methodology that helps develop predictive mode selection strategies based on
the anticipated radio link conditions. We also conduct a thorough system-level
evaluation of representative data dissemination strategies to confirm the
benefits of predictive solutions that employ D2D-enabled collaborative caching
at the wireless edge to lower contents delivery latency and improve data
acquisition reliability
Dynamic Modeling in Health Research as a framework for developing statistical applications free of misuse of statistics
We introduce a novel framework for developing statistical applications in health research, based on dynamic modeling of the investigated processes. We formulate the principles of dynamic modeling in health research, which are coherent to those in other fields of research. Dynamic models explicitly describe causal relations which are to be adequately accounted in statistical methods, making them free of misuse of statistics and statistical fallacy.
We propose the Dynamic Model of Population Health describing temporal changes in health indicators, having nature of state variables. The Dynamic Regression Method was developed as statistical method for the identification of the model. This method evaluates cohort trends for state variables at each age and calendar year. The method is illustrated by evaluating cohort trends for the Body Mass Index for men, using survey data collected in the years 1982, 1987, 1992, in North Karelia, Finland
Modeling local stationary behavior of Internet traffic
Non-stationary behavior of aggregated IP traffic patterns was demonstrated in a number of studies. However, noneof those did either consider practical aspects of this phenomenon or propose suitable model to capture it. Searching for model for IP traffic aggregates we introduce the concept of local stationarity and demonstrate that it allows to model traffic patterns measured in high-speed operational networks. The proposed model is on-line in nature and suitable for real-time estimation of the traffic state in terms of piecewise covariance stationary stochasticprocess. As a basic tool of the model we use change-pointstatistical test allowing us to dynamically and automaticallydetermine whether statistical characteristics of the traffic pattern changes and, if so, estimate new parameters of the traffic pattern. We provide numerical examples and discuss applications of the proposed model that include but not limited to dynamic resource reservation, routing with guaranteed bandwidth, etc
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