Juan Luis Font

Analysis of source code metrics from ns-2 and ns-3 network simulators

Abstract Ns-2 and its successor ns-3 are discrete-event simulators which are closely related to each other as they share common background, concepts and similar aims. Ns-3 is still under development, but it offers some interesting characteristics for developers while ns-2 still has a large user base. While other studies have compared different network simulators, focusing on performance measurements, in this paper we adopted a different approach by focusing on technical characteristics and using software metrics to obtain useful conclusions. We chose ns-2 and ns-3 for our case study because of the popularity of the former in research and the increasing use of the latter. This reflects the current situation where ns-3 has emerged as a viable alternative to ns-2 due to its features and design. The paper assesses the current state of both projects and their respective evolution supported by the measurements obtained from a broad set of software metrics. By considering other qualitative characteristics we obtained a summary of technical features of both simulators including, architectural design, software dependencies or documentation policies.

Architecture, design and source code comparison of ns-2 and ns-3 network simulators

Ns-2 and its successor ns-3 are discrete-event simulators. Ns-3 is still under development, but offers some interesting characteristics for developers while ns-2 still has a big user base. This paper remarks current differences between both tools from developers point of view. Leaving performance and resources consumption aside, technical issues described in the present paper might help to choose one or another alternative depending of simulation and project management requirements.

Network traffic analysis and evaluation of a multi-user virtual environment

Abstract Virtual world applications allow users to interact within a simulated world. Network responsiveness and reliability contribute to the user experience, thus being able to model and reproduce certain network scenarios is a key issue to assure proper user experience and for being able to provide an estimation of the required network resources. The present study aims to model the client network traffic for the virtual world application Open Wonderland as the basis to tools for evaluating its network requirements. A micro scale modelling was performed, studying the outgoing network traffic from a black box approach that omits the details of traffic generation of the subcomponents and focuses on their overall combined traffic. The model obtained provides high goodness of fit for audio and object synchronisation traffic, reflected in a Pearson correlation coefficient close to its maximum value and low deviation figures measured by Root Mean Square Deviation.

Heuristic usability evaluation on games: a modular approach

Heuristic evaluation is the preferred method to assess usability in games when experts conduct this evaluation. Many heuristics guidelines have been proposed attending to specificities of games but they only focus on specific subsets of games or platforms. In fact, to date the most used guideline to evaluate games usability is still Nielsen’s proposal, which is focused on generic software. As a result, most evaluations do not cover important aspects in games such as mobility, multiplayer interactions, enjoyability and playability, etc. To promote the usage of new heuristics adapted to different game and platform aspects we propose a modular approach based on the classification of existing game heuristics using metadata and a tool, MUSE (Meta-heUristics uSability Evaluation tool) for games, which allows a rebuild of heuristic guidelines based on metadata selection in order to obtain a customized list for every real evaluation case. The usage of these new rebuilt heuristic guidelines allows an explicit attendance to a wide range of usability aspects in games and a better detection of usability issues. We preliminarily evaluate MUSE with an analysis of two different games, using both the Nielsen’s heuristics and the customized heuristic lists generated by our tool.

Experimental study and modelling of Networked Virtual Environment server traffic

The paradigm of virtual world environment arises as an useful tool in diverse fields such as e-Health or education, where they provide a new way of communication and interaction with end users. Networking capabilities play an important role in these systems, which motivates the study and understanding of the gaming network traffic. The present work focuses on Open Wonderland, a system that provides the basis for the development of Networked Virtual Environments with educational or health purposes. The goal of this paper is defining a testing environment and modelling the behaviour of the outgoing network traffic at the server side.

Design, implementation and validation of a simulation tool for Networked Virtual Environments

The popularisation of Networked Virtual Environment (NVE) applications in several context, including social interaction and e-Health fields, makes them an interesting subject of study. The proper estimation of their network requirements are key to ensure a good user experience, an important factor that determines the acceptance and success of the applications. The studies focused on NVE with an important social component are relatively scarce. This paper presents the design, implementation and validation of a simulation tool to assist in the study of the requirements of a NVE application, Open Wonderland. This tool will facilitate the study of several parameters that define the user experience. The study describes the overall structure, development framework and models that define the traffic generation patterns and validates the simulation results by comparing its traces with real traffic from previous studies.

A PCI AER Co-Processor Evaluation Based on CPUs Performance Counters

Image processing in digital computer systems usually considers the visual information as a sequence of frames. These frames are from cameras that capture reality for a short period of time. They are renewed and transmitted at a rate of 25-30 frames per second, in a typical real-time scenario. Digital video processing has to process each frame in order to obtain a filter result or detect a feature on the input. This processing is usually based on very complex and expensive (in resources) operations for an efficient real-time application. Brain can perform very complex visual processing in real-time using relatively simple cells, called neurons, which codify the information into spikes. Spike-based processing is a relatively new approach that implements the processing by manipulating spikes one by one at the time they are transmitted, like a human brain. The spike-based philosophy for visual information processing based on the neuro-inspired Address Event Representation (AER) is achieving nowadays very high performances. In this work we study the low level performance for real-time scenarios of a spike-based co-processor connected to a conventional PC and implemented through a PCI board. These low level lacks are focused both in the software conversion of static frames into AER format and in the bottleneck of the PCI interface.