1,874 research outputs found
A Comprehensive Tutorial for Mobility Management in Data Networks
No full textThe convergence towards the IP protocol has made Internet access available almost everywhere; this has leveraged new expectations about continuous and seamless communication, especially when portable devices are involved. Mobility management is a key issue in this context. The original IP specification does not account for mobility. Nevertheless, since the beginning of the Internet there has been a continuous interest in managing nomadic hosts; this has brought to a large number of approaches and protocols that have faced the problem from different perspectives. This paper reviews different approaches to mobility management that have arisen during the years. It is intended to serve as a tutorial for this topic, which draws out the lesson learned until now and depicts a comprehensive picture to foster new ideas and solutions while avoiding duplication of past work
Dynamic Bandwidth Allocation for Wireless Networks in High-Mobility Environments
No full textScarceness of bandwidth is a common problem to all radio networks. The cellular structure with frequency reuse has been the solution for many years in the past; however, decreasing cell sizes results in increasing handoff requests and this could be critical in high mobility environments. Moreover, the cellular structure cannot ensure the best utilization of resources when the distribution of the users inside the system is not constant in time. In this paper we focus on handoff protection and efficient dynamic bandwidth allocation for multi-service networks in high-mobility environments, in presence of very simple strategies for the Call Admission Control, in order to assure scalability. We propose to find an optimal solution by using a new simple heuristic which exploits the prediction of the system behaviour made by some suitable network model; moreover, a more traditional approach based on a stochastic algorithm is derived from the Montecarlo methods for comparison. Simulation results show that the proposed heuristic approach performs better, especially in critical situations
A Control Architecture for Quality of Service and Resource Allocation in Multiservice IP Networks
No full textA multiservice IP network based on the DiffServ paradigm is considered, composed by Edge Routers (ER) and Core Routers (CR), forming a domain that is supervised by a Bandwidth Broker (BB). The traffic in the network belongs to three basic categories: Expedited Forwarding (EF), Assured Forwarding (AF) and Best-Effort (BE). Consistently with the DiffServ environment, CRs only treat aggregate flows; on the other hand, ERs keep perflow information (from external sources or other network Domains), and convey it to the BB, which knows at each time instant the number (and the bandwidth requirements) of flows in progress within the domain for both EF and AF traffic categories. A global strategy for admission control, bandwidth allocation and routing within the domain is introduced and discussed in the paper. The approach adopted is based on the combination of analytical and simulation models of traffic with service guarantees and of TCP aggregated traffic. The global scheme (under different traffic patterns) is investigated and the results of its application under different traffic loads are studied on a test network with a ns-2 simulation tool
User-centric mobility management for multimedia content access
No full textCurrent mobility protocols and architectures aremainly targeted to devices or applications and they usually lack the ability to support user-centric paradigms; moreover, they usually face a single aspect of the problem, i.e., terminal handover or session mobility. Full mobility support is only available to specific applications or protocols (e.g., SIP) but these approaches do not exploit all facilities for movement detection at the network/link layers and do not allow to use the same framework for different applications. This paper proposes a generic mobility framework for terminal handover and session migration. It pursues the user-centric paradigm and builds a cross-layer architecture, yielding to a high level of generality, applicability and flexibility. Unlike other approaches, it does not require any modification in correspondent peers and works with a minimal network infrastructure. Software implementations are described for two representative real-time multimedia applications, i.e., media streaming and interactive conference. The effectiveness of the framework was analyzed by means of both performance measurements in local and Internet testbeds and user evaluation during a live demo conducted at a national science exhibitio
Economic and Energetic Analysis of a Distributed Micro-Generation System in the Savona University Campus
No full textThe present article describes an important outstanding project at the Savona University Campus: the research team has
planned and designed the installation of a distributed generation plant which consists of a set of micro-cogeneration gas
turbines and a solar system composed by photovoltaic modules. In particular, the paper deals with the energetic and
economic analysis of this cogeneration system that is going to be installed in the University Campus. About the
energetic analysis, the heat and electricity consumptions of the Campus have been evaluated, in terms of kWh
consumed, in order to establish how many micro-turbines and photovoltaic modules will have to be installed; from the
economic point of view, the article reports the investment analysis in order to evaluate the payback period, considering
both the fixed and variable costs
Performance evaluation of a DHT-based Integrated Mobility Architecture
No full textInternet population is growing quickly: 1.8 billion people were connected to the Internet at the end of 2009 [1] and this number is expected to grow to 2.2 billions within 2013. Right now, these people are, and will be even more surrounded by heterogeneous devices with advanced networking and rendering capabilities; in their daily life, they will demand a wide set of services and the opportunity to access more and more content in a fast, flexible and reliable way. Notwithstanding, the Internet infrastructure is showing more and more its architectural limitations for what concerns both advanced service provisioning and content fruition. The networking community is beginning to argue that one of the main issues of the current Internet is its own communication paradigm: despite users want to communicate with each other or retrieve content as fast as possible, the communication is still in terms of pair of devices that have to be located and connected to each other. There are two ways of coping with this sort of "ossification" of the Internet. The first one is a clean-slate re-thinking of the network layer aimed at the design of a new L3 protocol able to overcome most of the IP limitations. The second one is an incremental addition of functionalities, mainly at the application layer, on top of the current network infrastructure. In this paper we will focus on what we believe is the common element among these two approaches, namely Distributed Hash Tables (DHTs), able to offer distribution and replication of information, high levels of scalability, resilience and selfadaptation, fast access to time-critical information, and much more
Design of UPnP based cooperative network connectivity proxy
No full textThe Internet connected edge devices require active
participation by generating and responding to routine applications/
protocols heart-beat messages. Failing to do this will result
in loss of their presence over the Internet. A huge amount of
energy is wasted every year to keep idle or unused network
hosts powered-up 24/7 only to maintain the network presence for
remote access, file sharing and other administrative management
reasons. Thus, reducing the energy waste of ICT is becoming
increasingly important due to rising costs of electricity, limited
natural resources and environmental concerns. This extended abstract
presents a new design of cooperative Network Connectivity
Proxy (NCP) to reduce the network energy consumption. The
NCP uses a low power entity that can maintain the network
presence for the high power devices and smartly allows them
to transition into low power sleep/active modes. The Universal
Plug and Play (UPnP) protocol, that allows seamless discovery
and communication between the network hosts can be wellsuited
approach for the design of NCP. All the hosts in the
local network can seamlessly interact and use the services offered
by the NCP. The UPnP based NCP includes a connectivity
management service that implements the key network presence
and management protocols like DHCP, ICMP, ARP etc. Thus,
the NCP can reduce the network energy consumption by 60 to
70% depending on the network host’s time usage model
Handling Mobility over the Network
No full textFuture Internet is expected to evolve towards user-centric paradigms, which leverage ubiquitous and pervasive communications. Mobility will be one of the key issues in such evolution. Current mobility protocols have a number of limitations and drawbacks; until now, there is not any general solution that could face all aspects of mobility. The only notable examples are targeted to specific applications. We believe that mobility could be effectively managed through overlay networks at the application layer. In this paper, we motivate our idea and depict some preliminary scenario about this topic
User-Centric Mobility for Multimedia Communication: Experience and Evaluation from a Live Demo
No full textNowadays people claim and expect pervasive
communications, with continuous and seamless media access;
that requires new communication paradigms beyond
the legacy network- and device-centric approaches, and
leads to the user-centric concept.
Mobility is a key issue in pervasive communications, and
session migration is the most related aspect with the usercentric
vision; however, despite of the fact that the user
should be at the center of the system, no evidence of user
involvement in the design and evaluation phase can be found
in the literature for this topic.
In this paper we describe the user evaluation we carried
out by a live demo open to a large heterogeneity of potential
users at a national science exhibition. Our purpose was
twofold: on the one hand, to evaluate users’ feeling with
our user-centric networking mobility framework based on
the concept of Personal Address and, on the other hand,
to figure out general indications for the whole research
community about user’s expectations and requirements for session migration
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