Dario Maggiorini

Adaptive Routing in Underwater Delay/Disruption Tolerant Sensor Networks

As an emerging technique, underwater sensor network (UWSN) will enable a wide range of aquatic applications. However, due to the adverse underwater environmental conditions as well as some system constraints, an underwater sensor network is usually viewed as an intermittently connected network (ICN) (or delay/disruption tolerant network (DTN)), which requires specialized routing protocols. Moreover, applications may have different requirements for different types of messages, as demands a smart protocol to handle packets adaptively. In this paper, we propose a novel routing protocol where routing is performed adaptively based on the types of messages and application requirements. This is obtained by exploiting message redundancy and resource reallocation in order to achieve different performance requirements. We demonstrate through simulations that our protocol can satisfy different application requirements and achieve a good trade-off among delivery ratio, end-to-end delay and energy consumption.

Aggregated Multicast—A Comparative Study

Abstract Though IP multicast is resource efficient in delivering data to a group of members simultaneously, it suffers from scalability problem with the number of concurrently active multicast groups because it requires a router to keep forwarding state for every multicast tree passing through it. To solve this state scalability problem, we proposed a scheme, called aggregated multicast. The key idea is that multiple groups are forced to share a single delivery tree. In our earlier work, we introduced the basic concept of aggregated multicast and presented some initial results to show that multicast state can be reduced. In this paper, we develop a more quantitative assessment of the cost/benefit trade-offs. We propose an algorithm to assign multicast groups to delivery trees with controllable cost and introduce metrics to measure multicast state and tree management overhead for multicast schemes. We then compare aggregated multicast with conventional multicast schemes, such as source specific tree scheme and shared tree scheme. Our extensive simulations show that aggregated multicast can achieve significant routing state and tree management overhead reduction while containing the expense of extra resources (bandwidth waste and tunnelling overhead). We conclude that aggregated multicast is a very cost-effective and promising direction for scalable transit domain multicast provisioning.

Towards Highly Adaptive Services for Mobile Computing

The heterogeneity of device capabilities, network conditions and user contexts that is associated with mobile computing has emphasized the need for more advanced forms of adaptation of Internet services. This paper presents a framework that addresses this issue by managing distributed profile information and adaptation policies, solving possible conflicts by means of an inference engine and prioritization techniques. The profile information considered in the framework is very broad, including user preferences, device and network capabilities, and user location and context. The framework has been validated by experiments on the efficiency of the proposed conflict resolution mechanism, and by the implementation of the main components of the architecture. The paper also illustrates a specific testbed application in the context of proximity marketing.

A survey on interactive games over mobile networks

The mobile revolution has brought us the possibility to enjoy our favorite applications anywhere and anytime. In this context, interactive games over mobile networks embody a fascinating case study both for their commercial success and for their technical challenges, thus, sparking interest and development. The current state of the art of interactive games over mobile networks is captured in this article. We discuss main requirements and analyze possible combinations of existing solutions to provide better support for highly interactive game sessions with mobile players. Copyright

Adaptive MPEG-4 Video Streaming with Bandwidth Estimation

The increasing popularity of streaming video is a cause for concern for the stability of the Internet because most streaming video content is currently delivered via UDP, without any end-to-end congestion control. Since the Internet relies on end systems implementing transmit rate regulation, there has recently been significant interest in congestion control mechanisms that are both fair to TCP and effective in delivering real-time streams. In this paper we design and implement a protocol that attempts to maximize the quality of real-time MPEG-4 video streams while simultaneously providing basic end-to-end congestion control. While several adaptive protocols have been proposed in the literature [20,27], the unique feature of our protocol, the Video Transport Protocol (VTP), is the use of receiver side bandwidth estimation. We deploy our protocol in a real network testbed and extensively study its behavior under varying link speeds and background traffic profiles using the FreeBSD Dummynet link emulator [23]. Our results show that VTP delivers consistent quality video in moderately congested networks and fairly shares bandwidth with TCP in all but a few extreme cases. We also describe some of the challenges in implementing an adaptive video streaming protocol.

BEAM: a distributed aggregated multicast protocol using bi-directional trees

IP multicast confronts a severe scalability problem when there are large numbers of multicast groups in the network due to state explosion and control explosion. In backbone networks, this state scalability problem is exacerbated, since there are potentially enormous multicast groups crossing backbone domains, in this paper, we propose a scalable protocol, called BEAM (bi-directional aggregate multicast), which uses the concept of aggregated multicast. BEAM is a distributed protocol using bi-directional trees. It is simple and easy to implement. Through simulations, we show that BEAM can greatly improve state scalability with very low overhead: up to 98% state and tree setup and maintenance overhead reduction with less than 0.14 bandwidth waste in our experiments.

A protocol to improve the state scalability of source specific multicast

Source specific multicast (SSM) is a viable solution for current multicast applications, since the driving applications to date are one to many, including Internet TV, distance learning, file distribution, streaming media, etc. It brings many benefits in billing, address allocation, and security. However, SSM still confronts the serious state scalability problem when there are a large number of simultaneous on-going multicast groups in the network. We propose a protocol to improve the state scalability of source specific multicast, which is called aggregated source specific multicast (ASSM). We design the detailed ASSM protocol and show that our solution can obtain significant multicast state and tree management overhead reduction while achieving transparency to end-users, compatibility with existing multicast technologies and low overhead.

DroidGlove: An android-based application for wrist rehabilitation

Serious games embody a class of applications able to produce real world benefits for individuals, or for the society, through the entertainment of players engaged in a game. The peculiarity of a fun participation and the vast variety of real benefits which can be generated have recently attracted an increasing number of researchers and practitioners toward this field. In this paper, we focus on the specific context of serious games related to healthcare and propose a mobile-based application for wrist rehabilitation. The proposed solution represents a prototype for a new generation of ubiquitous gametherapies.

Distributed Context Monitoring for the Adaptation of Continuous Services

This paper describes a middleware designed for distributed context acquisition and reconciliation intended to support the adaptation of continuous Internet services, like e.g., multimedia streaming. These services persist in time, and are characterized by multiple transmissions of data by the service provider, as a result of a single request from the user. Adapting these services to the current context requires the continuous monitoring of context data, and a real-time adjustment of the adaptation parameters upon the detection of a relevant context change. The proposed solution is based on asynchronous context change notifications, and specific techniques have been designed to minimize the number of unnecessary updates and the re-evaluation of policies. The paper also provides experimental results obtained by developing an adaptive video streaming system and running it on top of the proposed middleware.

Aggregated Multicast - A Comparative Study

Multicast state scalability is among the critical issues which delay the deployment of IP multicast. In our previous work, we proposed a scheme, called aggregated multicast to reduce multicast state. The key idea is that multiple groups are forced to share a single delivery tree. We presented some initial results to show that multicast state can be reduced. In this paper, we develop a more quantitative assessment of the cost/benefit trade-offs. We introduce metrics to measure multicast state and tree management overhead for multicast schemes. We then compare aggregated multicast with conventional multicast schemes, such as source specific tree scheme and shared tree scheme. Our extensive simulations show that aggregated multicast can achieve significant routing state and tree management overhead reduction while containing the expense of extra resources (bandwidth waste and tunnelling overhead, etc.). We conclude that aggregated multicast is a very cost-effective and promising direction for scalable transit domain multicast provisioning.