Search results for "IEEE"
showing 10 items of 135 documents
Understanding 802.11e contention-based prioritization mechanisms and their coexistence with legacy 802.11 stations
2005
The IEEE 802.11e task group has reached a stable consensus on two basic contention-based priority mechanisms to promote for standardization: usage of different arbitration interframe spaces and usage of different minimum/maximum contention windows. The goal of this article is to provide a thorough understanding of the principles behind their operation. To this purpose, rather than limit our investigation to high-level (e.g. throughput and delay) performance figures, we take a closer look at their detailed operation, also in terms of low-level performance metrics (e.g., the probability of accessing specific channel slots). Our investigation on one hand confirms that AIFS differentiation prov…
The IEEE-FIPA Standard on the Design Process Documentation Template
2014
Nowadays, it is a matter of fact that a “one-size-fit-all” methodology or design process useful and fitting every kind of problem, situation, or design context does not exist. (Situational) Method Engineering (SME) discipline aims at determining techniques and tools for developing ad hoc design methodologies. SME mainly and highly focuses on the reuse of portion of existing design processes or methodologies (the method fragments). In order to have means for creating SME techniques and tools and for creating new design processes, some key elements are needed: a unique process metamodel for representing design processes and fragments, a proper template for the description of AO design process…
The OpenUp Process
2014
The Open Unified Process (OpenUp) is an iterative design process that structures the project lifecycle into four phases: Inception, Elaboration, Construction, and Transition. It is part of the Eclipse Process Framework and embraces a pragmatic, agile philosophy that focuses on the collaborative nature of software development. It is a tools-agnostic, low-ceremony process that can be extended to address a broad variety of project types. The project lifecycle provides stakeholders and team members with visibility and decision points throughout the project and makes them able to manage their work through micro-increments.
Guaranteed access mode for downlink traffic over IEEE 802.11 WLANs
2011
IEEE 802.11 networks present an unfairness problem between the downlink and uplink traffic, using the default settings of the Enhanced Distributed Channel Access (EDCA). In order to reduce this unfairness, the Access Point (AP) can adapt the standard parameters, but this is not enough. In this paper, we propose simple and efficient solutions, which are implemented at the AP, thus they are standard compatible and no modifications to the current hardware and protocol stacks are needed. These solutions aim at providing guaranteed access to the downlink traffic when the AP perceives the unfairness problem. Our simulation results show a reduction in the unfairness and an enhancement in network p…
A Network Protocol to Enhance Robustness in Tree-Based WSNs Using Data Aggregation
2007
This paper proposes a data gathering strategy for wireless sensor networks and an implementation based on the IEEE 802.15.4 standard. The algorithm combines the benefits of single-path and multi-path routing strategies in a hybrid solution which makes use of alternative paths when necessary. We adopt a caching and retransmission technique, which exploits some peculiar features of data aggregation, with the use of implicit acknowledgments of reception. The paper also discusses simulation results that show how the mentioned techniques, combined with exploitation of the features of the IEEE 802.15.4 standard have been used to obtain an efficient protocol that takes energy consumption into acco…
QoS Based Routing Protocol for Intra-Mesh Infrastructure Communications
2015
International audience; Mesh Networks (WMNs) have been considered as a promising alternative to conventional wired networks, thanks to its flexibility and easy deployment. Thus, to ensure a satisfying level of QoS guarantees for real-time and streaming applications such as Voice over IP (VoIP) and Video on Demand (VoD), we propose a novel QoS based routing protocol for wireless mesh environments, called Hybrid QoS Mesh Routing (HQMR), jointly with a clustering algorithm to enhance scalability issues within the mesh infrastructure. HQMR is composed of two routing sub-protocols: a reactive routing sub-protocol for intra-infrastructure communications and a proactive QoS based multi-tree routin…
On the Interaction Between IEEE 802.11e and Routing Protocols in Mobile Ad-Hoc Networks
2005
The upcoming IEEE 802.11e standard was developed to offer QoS capabilities to WLAN, offering significative improvements to multimedia traffic. MANETs also benefit from this new technology since the most widely deployed and used wireless interfaces are IEEE 802.11 based. In this paper we expose results relative to the interaction of reactive routing protocols for MANETs and the IEEE 802.11e technology. We find that very substantial improvements in terms of throughput and normalized routing overhead are achieved due to increased routing responsiveness. We also detail the relation between the behavior experienced in each case and the internal mechanisms of the routing protocol being used, offe…
Reliable Data Gathering in Tree-Based IEEE 802.15.4 Wireless Sensor Networks
2007
This paper describes a routing protocol for enhanced robustness in IEEE 802.15.4-based sensor networks, which also addresses typical MAC layer issues, including power management, synchronization and link reliability. The algorithm uses a single-path strategy in error-free scenarios and resorts to using alternative paths when communication errors are detected. Our proposal exploits implicit acknowledgement of reception, a feature which may be provided by data aggregation when a broadcast medium such as the wireless channel is used. Therefore MAC layer acknowledgements are not used and errors recovery relies on a caching and retransmission strategy. The protocol requires synchronization among…
Performance Analysis in Spatially Correlated IEEE 802.11 Networks
2012
Wireless mesh networks are difficult to be characterized, especially under multi-hop traffic streams. The problem is that the local view of the channel and the correlation between the buffers of consecutive nodes in a stream path make complicated the identification of the contention level perceived by each station along the time. Such a figure is used in the models based on the so called decoupling assumption for evaluating the final scheduling of simultaneous channel access grants. In this paper we propose a simplified mesh network model focused on capturing the correlation due to the network topology and traffic routes rather than the access protocol state at each node. To this purpose, w…
Introduction
2014
Nowadays, software engineers face a wide range of particular application domains such as electronic commerce, enterprise resource planning, mobile computing, self-organisation, pervasive and adaptive computing, etc. The resulting heterogeneity and required functionalities call for complex systems and open architectures that may evolve dynamically over time so as to accommodate new components and meet new requirements. This is probably one of the main reasons why the agent metaphor and agent-based computing are gaining momentum in these areas.