SIMPS: Using Sociology for Personal Mobility

Assessing mobility in a thorough fashion is a crucial step toward more efficient mobile network design. Recent research on mobility has focused on two main points: analyzing models and studying their impact on data transport. These works investigate the consequences of mobility. In this paper, instead, we focus on the causes of mobility. Starting from established research in sociology, we propose SIMPS, a mobility model of human crowds with pedestrian motion. This model defines a process called sociostation, rendered by two complimentary behaviors, namely socialize and isolate, that regulate an individual with regard to her/his own sociability level. SIMPS leads to results that agree with scaling laws observed both in small-scale and large-scale human motion. Although our model defines only two simple individual behaviors, we observe many emerging collective behaviors (group formation/splitting, path formation, and evolution).     

Semaphore queues: modeling multilayered window flow controlmechanisms

An open queuing network for analyzing multilayered window flow control mechanisms consisting of different subnetworks is presented. The number of customers in each subnetwork is controlled by a semaphore queue. The queuing network is analyzed approximately using decomposition and aggregation. The approximation was validated against exact numerical and simulation data, and it was found to have an acceptable relative error. The queuing model is easy to implement, and it can be included in a software package. Using this queuing network, a case study involving the modeling and analysis of the ISO X25 flow control mechanism is presented     

Sensing Pollution on Online Social Networks: A Transportation Perspective

Transportation policy and planning strategies, as well as Intelligent Transportation Systems (ITS), can all play important roles in decreasing pollution levels and their negative effects. Interestingly, limited effort has been devoted to exploring the potential of social network analysis in such context. Social networks provide direct feedback from people and, hence, potentially valuable information. A post telling how a person feels about pollution at a given time at a given location, could be useful to policy-makers, planners or environmentally-aware ITS designers. This work verifies the feasibility of sensing air pollution from social networks and of integrating such information with real sensors feeds, unveiling how people advertise such phenomenon, acting themselves as smart objects, and how online posts relate to true pollution levels. This work explores a new dimension in pollution sensing for the benefit of environmental and transportation research in future smart cities, confronting over 1,500,000 posts and pollution readings obtained from governmental on-the-field sensors over a one-year span.     

Multicast for RSVP switching: An extended multicast model with QoS for label swapping in an IP over ATM environment

The ubiquity of IP associated with the acknowledgment of ATM as a key switching technology has motivated an increasing interest towards the design of a more efficient way of operating IP over ATM networks. This approach is known under the name Label Swapping. A few studies have addressed the primary issue of providing simultaneously quality of service and multicast. We propose a solution where we mix an RSVP architecture with one Label Swapping technique called IP Switching. We discuss problems that arise when using cut-through associated with an RSVP multicast model and propose an application for an IPv6 environment over an ATM switching hardware.     

A preferential attachment gathering mobility model

In this letter we propose a mobility model using preferential attachment via objects called attractors. We introduce a new kind of mobility we call Gathering Mobility, where nodes, although independent, exhibit a collective behavior. We show that this model, called Pragma, achieves a scale-free spatial distribution in the situation of population growth.     

Constraint-Based Geolocation of Internet Hosts

Geolocation of Internet hosts enables a new class of location-aware applications. Previous measurement-based approaches use reference hosts, called landmarks, with a well-known geographic location to provide the location estimation of a target host. This leads to a discrete space of answers, limiting the number of possible location estimates to the number of adopted landmarks. In contrast, we propose Constraint-Based Geolocation (CBG), which infers the geographic location of Internet hosts using multilateration with distance constraints to establish a continuous space of answers instead of a discrete one. However, to use multilateration in the Internet, the geographic distances from the landmarks to the target host have to be estimated based on delay measurements between these hosts. This is a challenging problem because the relationship between network delay and geographic distance in the Internet is perturbed by many factors, including queueing delays and the absence of great-circle paths between hosts. CBG accurately transforms delay measurements to geographic distance constraints, and then uses multilateration to infer the geolocation of the target host. Our experimental results show that CBG outperforms previous geolocation techniques. Moreover, in contrast to previous approaches, our method is able to assign a confidence region to each given location estimate. This allows a location-aware application to assess whether the location estimate is sufficiently accurate for its needs     

Reducing Latency and Overhead of Route Repair with Controlled Flooding

Ad hoc routing protocols that use broadcast for route discovery may be inefficient if the path between any source–destination pair is frequently broken. We propose and evaluate a simple mechanism that allows fast route repair in on demand ad hoc routing protocols. We apply our proposal to the Ad hoc On-demand Distance Vector (AODV) routing protocol. The proposed system is based on the Controlled Flooding (CF) framework, where alternative routes are established around the main original path between source–destination pairs. With alternative routing, data packets are forwarded through a secondary path without requiring the source to re-flood the whole network, as may be the case in AODV. We are interested in one-level alternative routing. We show that our proposal reduces the connection disruption probability as well as the frequency of broadcasts.     

Transport layer statistical multicast based on the XTP bucket algorithm

Multicast or point-to-multipoint transmission is becoming a major issue for supporting distributed multimedia applications. In this paper, we analyze the service provided by theXtp reliable multicast. We discover several problems and drawbacks, such as multiple retransmission of the same data packets or the protocol inefficiency when performing with large group size and non-broadcast networks. To overcome some of these problems, we introduce new constraints at the sender side to prevent any unnecessary retransmissions. We introduce the service semantic calledstatistical reliable to cope with large group size while keeping a high level of reliability (related to error recovery issues). The quality of service provided by this modified protocol is assessed by simulation experiments for two different network environments :Fddi andAtm. We show that the reliability is almost binary, i.e. all reliable or unreliable at all. If the parameters are correctly sized, we can expect to get an all reliable semantic while using the statistical reliable protocol with the benefit of low protocol overhead. We are now working on a modified version of the proposed protocol to specifically adressAtm based networks.     

An Underlay Strategy for Indirect Routing

The evolution of the Internet toward ubiquity, mobility, and independence of wired infrastructure requires revising routing in large dynamic clouds. The need for frequent address updates caused by node mobility suggests decoupling the permanent node identifier from its topological address. This paper proposes Tribe, an indirect and scalable routing protocol for self-organizing networks. Tribe provides an anchor-based abstraction, where the communication is split into two phases: location of the destination node and direct communication between source and destination, associated with appropriate addressing schemes. Tribe anchor nodes play the role of rendezvous points and are responsible for translating a node's identifier into a topology-dependent address. Tribe achieves high scalability by distributing location information among all nodes in the network using peer-to-peer concepts. By managing regions of a logical addressing space, Tribe nodes route in a hop-by-hop basis with small amount of information and communication cost. A qualitative analysis of the Tribe topology and a performance evaluation of the protocol behavior are provided. Tribe raises fundamental issues and triggers a high potential for future work.     

Integration of 3G Connectivity in PlanetLab Europe

Distributed research testbeds play a fundamental role in the evaluation of disruptive innovations for the Future Internet. In recent years, the main research funding agencies have promoted several initiatives aimed at designing and building open, large scale, realistic experimental facilities that could be used to evaluate innovative networking architectures, paradigms and services. In this paper, after discussing the main challenges in building such infrastructures, we present how, by leveraging the concept of federation, we managed to introduce a first degree of heterogeneity into PlanetLab Europe, a European testbed federated with PlanetLab, by providing UMTS connectivity to PlanetLab Europe nodes. Our contribution is just a first step of an evolutionary path whose further developments will lead to next generation large-scale heterogeneous testbeds for supporting experimentally-driven research on the Network of the Future (Preliminary results within the same framework of this work have been recently published in Canonico et al. (2007) and Botta et al. (2008)).