Irresponsible Forwarding Research Articles

DiSIF: A Distance-Based Silencing Technique for Multi-Hop Broadcast Communications in Pedestrian Ad-Hoc Networks

In this paper, we focus on a particular type of opportunistic ad-hoc networks, namely Pedestrian Ad-hoc NETworks (PANETs). In PANETs, nodes are densely distributed and each node may transmit information to all other nodes in the network via multi-hop broadcasting. Even though flooding is the simplest technique to broadcast information with multi-hop communications, it can be very inefficient because of redundant transmissions which may induce collisions. This problem is known, in the literature, as the “broadcast storm problem.” In this work, we present a novel probabilistic forwarding technique, denoted as Distance-based Silencing IF (DiSIF), which is derived from the probabilistic broadcasting protocol Irresponsible Forwarding (IF) and one of its extensions, denotes Silencing IF (SIF). The performance of the DiSIF protocol is analyzed and compared with those of other existing protocols, investigating the impact of fundamental network parameters. Lower bounds (exact and approximate) on the average number of hops, expedient to evaluate the propagation efficiency of DiSIF, are also derived. Finally, under the assumption that each node (e.g., a smartphone) relies on Global Positioning System (GPS) to estimate its position, the robustness of DiSIF against a GPS positioning error is investigated.

Clustering and sensing with decentralized detection in vehicular ad hoc networks

In the near future, vehicles will be more and more advanced sensing platforms: for instance, at least one smartphone (with several on-board sensors) is likely to be inside each vehicle. Smartphone-based inter-vehicle communications thus support the creation of vehicular sensor networks (VSNs). In this paper, we analyze the performance of clustered VSNs, where (hierarchical) decentralized detection schemes are used to estimate the status of an observed spatially constant phenomenon of interest. Clustering makes processing efficient and the architecture scalable. Our approach consists of the creation, during a downlink phase, of a clustered VSN topology through fast broadcast of control messages, started from a remote sink (e.g., in the cloud), through a novel clustering protocol, denoted as cluster-head election irresponsible forwarding (CEIF). This clustered VSN topology is then exploited, during an uplink phase, to collect sensed data from the vehicles and perform distributed detection. The performance of the proposed scheme is investigated considering mostly IEEE 802.11b (smartphone-based) as well as IEEE 802.11p (inter-vehicle) communications in both highway-like and urban-like scenarios. Our results highlight the existing trade-off between decision delay and energy efficiency. The proposed VSN-based distributed detection schemes have to cope with the “ephemeral” nature of clusters. Therefore, proper cluster maintenance strategies are needed to prolong the cluster lifetime and, as a consequence, the maximum amount of data which can be collected before clusters break. This leads to the concept of decentralized detection “on the move.”

Irresponsible Forwarding Under Real Intervehicle Spacing Distributions

One approach to the distribution of traffic information in a self-organizing traffic information system is multihop broadcasting. In this approach, each vehicle may simply rebroadcast an information packet that it receives from the others. However, rebroadcasting results in redundant retransmissions of the same information, leading to a useless occupation of the radio channel. Minimizing redundancy, while still guaranteeing reachability in the network, is a challenging task in multihop broadcasting. In our previous work, we introduced a new probabilistic-based broadcasting scheme, i.e., Irresponsible Forwarding (IF) , which could effectively reduce the redundancy. However, in the previous work, we only considered the scenario where the intervehicle spacing was exponentially distributed. In this paper, we generalize the concept of IF such that it can be applied to any intervehicle spacing distribution. In addition, we evaluate the performance of the IF protocol when it is applied in a realistic scenario (i.e., using real traffic traces). This paper shows that the IF protocol is able to limit packet redundancy all hours of the day effectively.

I2V Highway and Urban Vehicular Networks: A Comparative Analysis of the Impact of Mobility on Broadcast Data Dissemination

In this paper, we consider the problem of disseminating data in Infrastructure-to-Vehicular (I2V) IEEE 802.11 networks. We analyze, with acomparative approach, the performance in highway and urban scenarios.In particular, after characterizing the mobility in these scenarios we analyze the performance in terms of data dissemination from a fixed Road Side Unit (RSU) to the vehicles passing in its proximity through a recently proposed multihop probabilistic broadcasting protocol, namely Irresponsible Forwarding (IF). In the case of highway-like Vehicular Ad-Hoc NETworks (VANETs), we first characterize a mobile scenario in such a way to make a direct comparison with a static scenario meaningful, taking into account a physical characterization of the network (e.g., in termsof vehicle spatial density). Then, we consider a few mobile urban scenarios, characterized by the presence of junctions regulated byTraffic Lights (TLs) and Roundabouts (Rs). Our results show that, from a single packet perspective, the vehicles' mobility does not affect the behavior of the IF protocol, at least in the considered mobile scenarios (both highway and urban). However, different conclusions are reached when an information flow (i.e., a series of consecutive packets) is considered. In this context, we determine the maximum amount of data which can be transferred from the RSU to the mobile vehicles passing through a certain Region Of Interest (ROI) around the RSU.