Home-work carpooling for social mixing Librino, Federico; Renda, M. Elena; Santi, Paolo ...
Transportation,
10/2020, Letnik:
47, Številka:
5
Journal Article
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Shared mobility is widely recognized for its contribution in reducing carbon footprint, traffic congestion, parking needs and transportation-related costs in urban and suburban areas. In this ...context, the use of carpooling in home-work commute is particularly appealing for its potential of lessening the number of cars and kilometers traveled, consequently reducing major causes of traffic in cities. Accordingly, most of the carpooling algorithms are optimized for reducing total travel time, cost, and other transportation-related metrics. In this paper, we analyze carpooling from a new perspective, investigating the question of whether it can be used also as a tool to favor social integration, and to what extent social benefits should be traded off with transportation efficiency. By incorporating traveler’s social characteristics into a recently introduced network-based approach to model ride-sharing opportunities, we define two social-related carpooling problems: how to maximize the number of rides shared between people belonging to different social groups, and how to maximize the amount of time people spend together along the ride. For each of the problems, we provide corresponding optimal and computationally efficient solutions. We then demonstrate our approach on two datasets collected in the city of Pisa, Italy, and Cambridge, US, and quantify the potential social benefits of carpooling, and how they can be traded off with traditional transportation-related metrics. When collectively considered, the models, algorithms, and results presented in this paper broaden the perspective from which carpooling problems are typically analyzed to encompass multiple disciplines including urban planning, public policy, and social sciences.
We analyze the performance of an interference-aware opportunistic relay selection protocol for multi-hop line networks which is based on the following simple rule: a node always transmits if it has a ...packet, except when its successive node on the line is transmitting. We derive analytically the saturation throughput and the end-to-end delay for two and three hop networks, and present simulation results for higher numbers of hops. In the case of three hops, we determine the throughput-optimal relay positions.
In this paper, we address the problem of packet forwarding in multi-hop wireless networks of nodes equipped with multiple antennas. Through the use of MIMO (multiple-input multiple-output) ...technology, the physical layer is able to superimpose multiple concurrent information flows, thereby increasing the communications parallelism in the network. We propose a cooperative cross-layer scheme that integrates distributed incremental redundancy hybrid automatic retransmission request (HARQ) error control with routing in order to increase the efficiency of the transmissions and decrease the interference load in the network. In the proposed scheme, next hop relays are opportunistically selected during the HARQ process in order to avoid overloaded receivers and guarantee the geographical advancement of the packets. Thus, cooperation is used to both strengthen weak links and select the path to the destination. Numerical results are presented for a specific instantiation where a layered space-time multiuser detection (LASTMUD) transmitter-receiver architecture with spread-spectrum signals is implemented at the physical layer and packets are encoded with a linear erasure code (LEC).
Infrastructure sharing has been recently investigated as a viable solution to increase the performance of coexisting wireless networks. In this paper, we analyze a scenario where two wireless ...networks are willing to share some of their nodes to gain benefits in terms of lower packet delivery delay and reduced loss probability. Bayesian Network analysis is exploited to compute the correlation between local parameters and overall performance, whereas the selection of the nodes to share is made by means of a game theoretic approach. Our results are then validated through use of a system level simulator, which shows that an accurate selection of the shared nodes can significantly increase the performance gain with respect to a random selection scheme.
The computation of the intersection area of a large number of circles with known centers and radii is a challenging geometric problem. Nevertheless, its resolution finds several applications in the ...analysis and modeling of wireless networks. Prior literature discusses up to three circles and even in this case there are many possible geometric configurations, each leading to a different involved close-form expression for the intersection area. In this paper, we derive two novel geometric results, that allow the check of the existence and the computation of the area of the intersection regions generated by more than three circles by simple algebraic manipulations of the intersection areas of a smaller number of circles. Based on these results, we construct an iterative algorithm based on a trellis structure that efficiently computes the intersection areas of an arbitrary number of circles. As an example of practical application of our results, we derive the probability that a fixed number of mobiles can be reliably allocated to a set of base stations in code division multiple access-based cellular networks.
Random access techniques have traditionally been used for the design of efficient medium access control protocols for wireless networks where the entire bandwidth is provided to the users as a single ...channel to be accessed for communication. In this paper we analyze the broadcast performance of several random access techniques in a multi channel system, where users can dynamically access portions of the available bandwidth at a given time and location. In order to compare these protocols we focus on metrics of interest such as the receiving probability, the system throughput and the network blocking probability. Our results show that these protocols can offer significant improvements in terms of increased system throughput provided that their operational parameters are carefully tuned to achieve near-optimal behavior in a multi channel setting.
Cooperative Network-Coded Hybrid ARQ (Coop-NC HARQ) has recently been proposed as a smart way to improve Decode & Forward (D&F) relaying. According to this idea, cooperators send HARQ redundancy on ...behalf of a source coded together with a data packet intended for the destination they are helping and taken from their own queue. This paper applies for the first time such a technique in ad hoc networks with Multi-User Detection (MUD) capabilities, allowing several terminals to simultaneously act as relays. In this context, we introduce a novel communication paradigm that leverages network-coded retransmissions to allow more efficient data exchanges among all terminals involved in a cooperative process, enabling inter-relay communications as well. Simulation results show that the proposed solution offers important gains over D&F as well as Coop-NC HARQ in both single- and multi-hop networks in terms of throughput and energy consumption.
Cooperation has proved to be an effective technique for improving the performance and the efficiency of wireless networks. Most of the existing work on cooperation focuses on the physical layer, with ...the aim of enhancing the capacity and the quality of a single link. In this paper we propose a cooperative protocol that melds physical, MAC and routing layers to increase the performance of a MIMO-BLAST ad hoc network, where nodes are allowed to transmit simultaneously. Nodes try to resolve in-range delivery of packets with an adaptive distributed Hybrid ARQ scheme to counteract interference from simultaneously active communications, while dynamic route selection is implemented for avoiding transmissions over links with harsh fading conditions. We assess the performance of our scheme through detailed simulations.
In this paper we address the deployment of cooperation in a cellular CDMA environment. In particular, we consider the use of amplify and forward to increase the maximum number of users that can be ...assigned to each base station. In our scenario, a certain number of fixed relay stations are positioned within the cell: each of them is assigned a group of mobile terminals, whose transmissions are received and retransmitted towards the base station. We study the rule for the assignment of mobile terminals to the fixed relay stations placed in the cell and we investigate the transmission power required by each user in order to reach a given average signal to interference plus noise ratio (SINR) level. We present numerical results quantifying the increased capability of a cell to accommodate users granted by cooperation in terms of coverage range and dropping probability.
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