Pietro Manzoni

Routing mechanisms for mobile ad hoc networks based on the energy drain rate

Untethered nodes in mobile ad hoc networks strongly depend on the efficient use of their batteries. In this paper, we propose a new metric, the drain rate, to forecast the lifetime of nodes according to current traffic conditions. This metric is combined with the value of the remaining battery capacity to determine which nodes can be part of an active route. We describe new route selection mechanisms for MANET routing protocols, which we call the minimum drain rate (MDR) and the conditional minimum drain rate (CMDR). MDR extends nodal battery life and the duration of paths, while CMDR also minimizes the total transmission energy consumed per packet. Using the ns-2 simulator and the dynamic source routing (DSR) protocol, we compare MDR and CMDR against prior proposals for energy-aware routing and show that using the drain rate for energy-aware route selection offers superior performance results. Methods keywords are system design and simulations.

A performance comparison of energy consumption for Mobile Ad Hoc Network routing protocols

The design of efficient routing protocols is a fundamental problem in a Mobile Ad-Hoc Network (MANET). Many different protocols have been proposed in the literature, each one based on different characteristics and properties. Some of these protocols have been studied and their performances have been evaluated in detail, focusing on aspects such as routing overhead latency and route length. We concentrate on the energy consumption issues of routing protocols. We present a performance comparison of the DSR, AODV, TORA and DSDV routing protocols with respect to energy consumption, evaluating how the different approaches and algorithms affect the energy usage in mobile devices.

ANEJOS: a java based simulator for ad hoc networks

Abstract Ad hoc networks are multi-hop wireless networks where mobile devices communicate using a shared, low power, low bandwidth channel without any wired infrastructure: each node acts also as a router of its neighbors. Ad hoc networks protocol design is still a new and growing research area; there currently is an IETF Working Group working on the definition of a standard for such networks. Various proposals are being evaluated and the need for a common comparison framework arises. This paper presents a simulator called ANEJOS (ad hoc networks Java simulator). The simulator is written in Java and is based on the SimJava tool and allows to be adapted to various routing protocols. It also allows considering other relevant aspects to ad hoc networks, like mobility patterns and traffic generation patterns. ANEJOS shared our models with other researchers through the internet, we can use Java applets inside HTML pages containing the whole simulator.

Determination of Critical Transmission Range in Ad-Hoc Networks

Ad-hoc networks are wireless mobile networks that do not rely on preexisting infrastructure. In such networks, multi-hop routing is used to achieve large degree of network connectivity and each node in the network acts as a router for its neighbors. The range of the radio transceivers is chosen as a trade-off between full network connectivity, the reuse of the available spectrum, and power consumption. This paper presents an algorithm to calculate the minimum transmission range of the transceivers that is required to achieve, with some probability, full network connectivity. Furthermore, we also study the effect of mobility on this value.

HOP: achieving efficient anonymity in MANETs by combining HIP, OLSR, and pseudonyms

Offering secure and anonymous communications in mobile ad hoc networking environments is essential to achieve confidence and privacy, thus promoting widespread adoption of this kind of networks. In addition, some minimum performance levels must be achieved for any solution to be practical and become widely adopted. In this paper, we propose and implement HOP, a novel solution based on cryptographic Host Identity Protocol (HIP) that offers security and user-level anonymity in MANET environments while maintaining good performance levels. In particular, we introduce enhancements to the authentication process to achieve Host Identity Tag (HIT) relationship anonymity, along with source/destination HIT anonymity when combined with multihoming. Afterward we detail how we integrate our improved version of HIP with the OLSR routing protocol to achieve efficient support for pseudonyms. We implemented our proposal in an experimental testbed, and the results obtained show that performance levels achieved are quite good, and that the integration with OLSR is achieved with a low overhead.Offering secure and anonymous communications in mobile ad hoc networking environments is essential to achieve confidence and privacy, thus promoting widespread adoption of this kind of networks. In addition, some minimum performance levels must be achieved for any solution to be practical and become widely adopted. In this paper, we propose and implement HOP, a novel solution based on cryptographic Host Identity Protocol (HIP) that offers security and user-level anonymity in MANET environments while maintaining good performance levels. In particular, we introduce enhancements to the authentication process to achieve Host Identity Tag (HIT) relationship anonymity, along with source/destination HIT anonymity when combined with multihoming. Afterward we detail how we integrate our improved version of HIP with the OLSR routing protocol to achieve efficient support for pseudonyms. We implemented our proposal in an experimental testbed, and the results obtained show that performance levels achieved are quite good, and that the integration with OLSR is achieved with a low overhead.

Emergency Services in Future Intelligent Transportation Systems Based on Vehicular Communication Networks

Over the years, we have harnessed the power of computing to improve the speed of operations and increase in productivity. Also, we have witnessed the merging of computing and telecommunications. This excellent combination of two important fields has propelled our capability even further, allowing us to communicate anytime and anywhere, improving our work flow and increasing our quality of life tremendously. The next wave of evolution we foresee is the convergence of telecommunication, computing, wireless, and transportation technologies. Once this happens, our roads and highways will be both our communications and transportation platforms, which will completely revolutionize when and how we access services and entertainment, how we communicate, commute, navigate, etc., in the coming future. This paper presents an overview of the current state-of-the-art, discusses current projects, their goals, and finally highlights how emergency services and road safety will evolve with the blending of vehicular communication networks with road transportation.

CityMob: A Mobility Model Pattern Generator for VANETs

Ad hoc networking is regarded as an adequate solution to cooperative driving between communicating cars on the road. Deploying and testing these networks, usually known as Vehicular Ad-hoc Networks (VANETs), involves a high cost in the real world, and so simulation is an useful alternative in research. One of the most critical issues in a simulation study of VANETs is the use of a mobility model which resembles, as closely as possible, the real behavior of vehicular traffic. Mobility models are crucial to obtain accurate and meaningful simulation results. In this paper we present CityMob, a mobility pattern generator for VANETs. Citymob allows researchers to easily create urban mobility scenarios, including the possibility to model car accidents. We designed and developed it targeting compatibility with the ns- 2 simulator, and we implemented three different mobility models: Simple Model (SM), Manhattan Model (MM) and Downtown Model (DM). Based on a flooding alert protocol we show that the most realistic mobility model to simulate traffic accidents is the Downtown model. We also find that, for flooding to be effective, a moderate number of vehicles is required.

Improving Selfish Node Detection in MANETs Using a Collaborative Watchdog

Mobile ad-hoc networks (MANETs) are composed of mobile nodes connected by wireless links without using any pre-existent infrastructure. MANET nodes rely on network cooperation schemes to properly work, forwarding traffic unrelated to its own use. However, in the real world, most nodes may have a selfish behavior, being unwilling to forward packets for others in order to save resources. Therefore, detecting these nodes is essential for network performance. Watchdogs are used to detect selfish nodes in computer networks. A way to reduce the detection time and to improve the accuracy of watchdogs is the collaborative approach. This paper proposes a collaborative watchdog based on contact dissemination of the detected selfish nodes. Then, we introduce an analytical model to evaluate the detection time and the cost of this collaborative approach. Numerical results show that our collaborative watchdog can dramatically reduce the overall detection time with a reduced overhead.

Realistic Radio Propagation Models (RPMs) for VANET Simulations

Deploying and testing Vehicular Ad hoc Networks (VANETs) involves high cost and intensive labor. Hence simulation is a useful alternative prior to actual implementation. Most works found in the literature employ very simplistic Radio Propagation Models (RPMs), ignoring the dramatic effects presented by buildings on radio signals. In this paper, we present three different RPMs that increase the level of realism, thereby allowing us to obtain more accurate and meaningful results. These models are: (a) the Distance Attenuation Model (DAM), (b) the Building Model (BM), and (c) the Building and Distance Attenuation Model (BDAM). We evaluated these different models and compared them with the Two-ray Ground model implemented in ns-2. We then carried out further study to evaluate the impact of varying some important parameters such as vehicle density and building size on VANET warning message dissemination. Simulation results confirmed that our proposed BDAM significantly affects the percentage of blind vehicles present and the number of received warning messages, and that our models can better reflect realistic scenarios.

Impact of mobility on TCP/IP: an integrated performance study

This paper presents a simulation analysis of the impact of mobility on TCP/IP augmented with features to support host mobility in wide area networks. Our results show that the existing version of TCP can yield low throughput in highly mobile environments due to the fact that TCP cannot discriminate packets dropped due to hand-offs with those dropped due to congestion in one or more network resources. As a result, TCP invokes a congestion recovery process when packets are lost during internetwork hand-offs of the mobile host. We investigate a proposal in which the transport layer explicitly receives information from the network layer of any ongoing mobility. We show that by effectively capitalizing this information, TCP can appropriately extend the slow-start phase in the recovery process and achieve higher throughput. Based on the simulation analysis we also show the robustness of this scheme in the presence of both host mobility and network congestion. >