Industrial networks rely on Ethernet and its complementary Time Sensitive Networking standards to support critical application requirements such as bounded latency and low jitter. To meet these requirements, precise time synchronization across wired devices is typically achieved across the wired devices via the Precision Time Protocol (PTP). PTP as a UDP-based protocol can synchronize wireless devices as well, provided that these guarantee hardware-based timestamping. On the other hand, Wi-Fi integrates time synchronization mechanisms better suited to its shared medium, such as the the Fine Time Measurement (FTM) protocol. Aiming at contributing to the time synchronization solution across multi-AP industrial environments, this paper proposes a hiearchical FTM-based synchronization approach capable of supporting time synchronization in a way compatible with Ethernet/TSN. The evaluation of the proposed solution carried out with the ns-3 DetNetWiFi framework, shows that it successfully synchronizes all devices within the networ with an accuracy of less than 5 μs and providing fairness in terms of balancing FTM requests in dense networks effectively.

This paper addresses Wi-Fi 6 time-aware scheduling based on Target Wake Time (TWT) in a way that is compatible with the Time Sensitive Networking (TSN) Time-aware Shaper (TAS). The paper proposes novel mechanisms and describes a proof-of-concept implementation. The implemented solution has been evaluated in terms of latency and jitter in a testbed with operational Wi-Fi 6 equipment. Results achieved in terms of latency and jitter show that our proposal provides a way to isolate critical traffic from other types of traffic in an effective and flexible way.

After briefly introducing aspects concerning Mobile Augmented Reality Systems, this article delves into the evolution of these systems as pervasive technology. The work debates also on acceptance of this technology in the context of outdoor applications. The need to develop context-aware, close-to-real-time feedback mechanisms that take into consideration a continuous measurement of Quality of Experience is also discussed. For this purpose, the work goes over how to integrate user preferences into context-aware feedback systems, proposing a theoretical model for measuring Quality of Experience. The model is derived from an analysis of previous technology adoption models and incorporates the knowledge of user preferences. This knowledge has been gathered via a public questionnaire.

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This work evaluates three Fog Computing data placement algorithms via experiments carried out with the iFogSim simulator. The paper describes the three algorithms (Cloud-only, Mapping, Edge-ward) in the context of an Internet of Things scenario, which has been based on an e-Health system with variations in applications and network topology. Results achieved show that edge placement strategies are beneficial to assist cloud computing in lowering latency and cloud energy expenditure.

This paper contributes to the topic of mobility management anticipation via the exploitation of preferred network ranking utility functions. The work proposes, implements, and evaluates a set of ranking functions based on Quality of Service and Quality of Experience indicators. Such indicators are obtained via wireless overhearing, or via active network probing. The functions also take into consideration recommendations from neighboring nodes. The implementation of the functions has been integrated into open-source software. The proposed implementation is evaluated via experiments carried out on a wireless testbed in terms of handover time to completion, total handovers successfully achieved, and rejected handovers. Results obtained show that overhearing is relevant to estimate mobility, as it brings in more sensitivity and lowers the cost of active probing.

In the context of social well-being and context awareness several eHealth applications have been focused on tracking activities, such as sleep or specific fitness habits, with the purpose of promoting physical well-being with increasing success. Sensing technology can, however, be applied to improve social well-being, in addition to physical well-being. This paper addresses NSense, a tool that has been developed to capture and to infer social interaction patterns aiming to assist in the promotion of social well-being. Experiments carried out under realistic settings validate the NSense performance in terms of its capability to infer social interaction context based on our proposed computational utility functions. Traces obtained during the experiments are available via the CRAWDAD international trace repository.

Wireless networks are today employed as complementary access technology, implemented on the last hop towards the Internet end-user. The shared media that wireless deployments provide and which is relevant to interconnect multiple users has a limited technical design, as only one device can be served per unit of time, design aspect that limits the potential applicability of wireless in dense environments. This paper proposes and evaluates a novel MAC-layer mechanism that extends current wireless networks with the possibility to perform downstream transmission to multiple devices within a single transmission time-frame, resulting in improved fairness for all devices. The mechanism, which is software-defined, is backward-compatible with current wireless standards and does not require any hardware changes. The solution has been validated in a realistic testbed, and the paper provides details concerning the computational aspects of our solution; a description of the implementation; and results extracted under different realistic scenarios in terms of throughput, packet loss, as well as jitter.

This paper addresses the problematic of mobility management decomposition, as a first step towards the development of decentralized mobility management architectures. We propose and evaluate an IP mobility management solution based on the decoupling of data and control plane. We have carried out simulations, showing that the proposed approach can significantly reduce packet loss and reachability time for mobile nodes.

This paper presents a summary of work aimed at making current multihop routing in mobile ad hoc networks more sensitive to node mobility and ultimately improve routing performance in the face of node mobility. We discuss the various existing mobility tracking parameters, how they capture node mobility and also their shortfalls. We propose some mobility tracking schemes(heuristics) based on one of the mobility tracking parameters(Link Duration) and also show the performance of one of the proposed heuristics.

This work is focused on explore different heuristics that may be applied to provide a link-based cost for energy-aware multihop routing for wireless environments which integrate heterogeneous devices that are carried or owned by Internet end-users. We propose to analyze based on simulations of the different heuristics when applied to both distance-vector and link-state approaches, namely the AODV and OLSR routing protocols.

Wireless networks growing popularity coupled with a wide availability of wireless-enabled personal devices is today the basis for user-centric Internet architectures to evolve. Central to this new paradigm of user-centricity is the fact that today the Internet end-user exhibits a highly nomadic behavior, where most of the portable devices are carried by humans. The thesis proposed relates to the recent trend of social mobility modeling as a way to improve mobile network operation. The work is focused on the analysis of social mobility models and how to propose new models having in mind an overall network optimization due to the possibility to predict adequately node movement on mobile networks.

Ethernet's plug-&-play feature is built on its use of flat (location independent) addresses and use of broadcasts to resolve unknown MAC addresses. While plug-&-play is one of Ethernet's most attractive features, it also affects its scalability. As the number of active MAC addresses in the network grows beyond the capacity of forwarding caches in bridges, the odds of "cache-misses," each triggering a broadcast, grow as well. The resulting increase in broadcast bandwidth consumption affects scalability. To address this problem, we propose a simple address resolution scheme based on an adaptation of distributed hash tables where a single query suffices in the steady state. The new scheme is implemented on advanced bridges maintaining backward compatibility with legacy bridges and eliminating reliance on broadcasts for address discovery. Comparisons with a legacy, broadcast-based scheme are carried out along several metrics that demonstrate the new scheme's robustness and ability to improve scalability.

The use of multiple interfaces to access heterogeneous networks is becoming a strong reality to end-users. Hence one realistic problem is how to select a specific access interface (and consequently network) as well as how to perform smooth and seamless handover among different types of technologies. In this paper we propose a dynamic and user-centric network selection and decision process which optimizes handover across heterogeneous networks. A satisfaction degree function (SDF) is used to evaluate, according to user's predefined criteria, available networks and select the best one(s) according to such criteria. The criteria consider incorporating user policies and information from several OSI layers, including dynamic network status and application requirements. Numerical results show that the proposed network selection process results in the choice of the best network according to the user's choices.

The Mobile WiMAX standard (IEEE 802.16e-2005) brings wireless broadband to a new level due to the support of nomadism. Still, handover latency in Mobile WiMAX is an issue that may affect real-time continuity of application sessions. This is partially due to the Layer 2 scanning/ranging, as well as the network re-entry procedure, which may result in a latency of hundreds of milliseconds, far exceeding the requirement of typical real-time services (e.g., 150 ms for Voice over IP). In this paper, we describe a mechanism which incorporates information from several OSI Layers to speed up the Layer 2 handover. We show by means of simulations that this new mechanism can decrease the handover latency significantly, to less than 100 ms in most cases.

In order to achieve better scalability, inter-domain signaling protocols rely on aggregation to reduce the amount of state information that routers are required to maintain. Nonetheless, they do not address another scalability key factor, the signaling load associated with establishing and maintaining reservations. Such load can be reduced if bandwidth is over-reserved. Over-reservation allows accommodating reservations without exchanging signaling messages, but may result in additional blocking. In this paper, we carry out a systematic investigation of the impact of over-reservation in different aggregation approaches, evaluating such impact in terms of the achieved signaling reduction, and blocking.

Current quality of service models such as those embodied in the differentiated services proposal, rely on data path aggregation to achieve scalability. Data path aggregation bundles into a single aggregate multiple flows with the same quality requirements, hence decreasing the amount of state to be kept. A similar scalability concern exists on the control path, where the state required to account for individual reservations needs to be minimized. There have been several proposals aimed at control path aggregation, and the goal of the paper is to expand on these works in an attempt to gain a better understanding of the various parameters that influence the efficiency of different approaches. In particular, we focus on inter-domain control aggregation, and compare an autonomous system (AS) sink-tree based approach with two examples of a shared AS segment based approach, in terms of the amount of state kept, both per AS and per edge router Our main contributions are in providing a greater understanding into the design of efficient control path aggregation methods.