arXiv subjects

Juan M. Ramirez-Cortes

Publications and source records attributed to Juan M. Ramirez-Cortes.

3 recordsLinked to original sources

arXiv2011

Mathematical Model for the Optimal Utilization Percentile in M/M/1 Systems: A Contribution about Knees in Performance Curves

Performance curves of queuing systems can be analyzed by separating them into three regions: the flat region, the knee region, and the exponential region. Practical considerations, usually locate the knee region between 70-90% of the theoretical maximum utilization. However, there is not a clear agreement about where the boundaries between regions are, and where exactly the utilization knee is located. An open debate about knees in performance curves was undertaken at least 20 years ago. This historical debate is mainly divided between those who claim that a knee in the curve is not a well-defined term in mathematics, or it is a subjective and not really meaningful concept, and those who define knees mathematically and consider their relevance and application. In this paper, we present a mathematical model and analysis for identifying the three mentioned regions on performance curves for M/M/1 systems; specifically, we found the knees, or optimal utilization percentiles, at the vertices of the hyperbolas that relate response time as a function of utilization. Using these results, we argue that an adaptive and optimal queuing system could be deployed by keeping load and throughput within the knee region.

cs.PF↗

arXiv2011

Towards a Cognitive Handoff for the Future Internet: Model-driven Methodology and Taxonomy of Scenarios

A cognitive handoff is a multipurpose handoff that achieves many desirable features simultaneously; e.g., seamlessness, autonomy, security, correctness, adaptability, etc. But, the development of cognitive handoffs is a challenging task that has not been properly addressed in the literature. In this paper, we discuss the difficulties of developing cognitive handoffs and propose a new model-driven methodology for their systematic development. The theoretical framework of this methodology is the holistic approach, the functional decomposition method, the model-based design paradigm, and the theory of design as scientific problem-solving. We applied the proposed methodology and obtained the following results: (i) a correspondence between handoff purposes and quantitative environment information, (ii) a novel taxonomy of handoff mobility scenarios, and (iii) an original state-based model representing the functional behavior of the handoff process.

cs.NI↗

arXiv2011

Towards a Cognitive Handoff for the Future Internet: A Holistic Vision

Current handoffs are not designed to achieve multiple desirable features simultaneously. This weakness has resulted in handoff schemes that are seamless but not adaptive, or adaptive but not secure, or secure but not autonomous, or autonomous but not correct, etc. To face this limitation, we initiated a research project to develop a new kind of handoff system which attains multiple purposes simultaneously by using context information from the external and internal handoff environment. We envision a cognitive handoff as a multipurpose, multi-criteria, environment-aware, and policy-based handoff that trades-off multiple objectives to reach its intended goals. This paper presents a conceptual (soft) model of cognitive handoffs using a holistic approach. We applied the proposed model to identify cognitive handoff performance parameters and tradeoffs between conflicting objectives. We argue that cognitive handoffs are the archetype of handoffs for the future Internet.

cs.NI↗