844 research outputs found
Implementation of the AODV Routing in an Energy-constrained Mesh Network
Wireless sensor networks (WSNs) compose the fundamental platform for a number of Internet of Things (IoT) applications, especially those related to the environmental, health, and military surveillance. While being autonomous in power supply, the main challenge in node’s processing and communication architecture design remains the energy efficiency. However, this goal should not limit the main functionality of the system which is often related to the network coverage and connectivity. This paper shows the implementation of the Ad-hoc On-demand Distance Vector (AODV) routing algorithm in an XBee based platform. As shown, the network can achieve low power consumption per node primarily due to the energy efficiency of the wireless transceivers and the due to the capability of the firmware to enable different operation modes. On the other hand, while inheriting the advantages of flooding-based route discovery protocols, the implemented AODV algorithm further minimizes the data and processing overhead, which implies the additional lifetime prolongation of the energy-constrained mesh network
Resource-efficient strategies for mobile ad-hoc networking
The ubiquity and widespread availability of wireless mobile devices with ever increasing
inter-connectivity (e. g. by means of Bluetooth, WiFi or UWB) have led to new and emerging
next generation mobile communication paradigms, such as the Mobile Ad-hoc NETworks
(MANETs). MANETs are differentiated from traditional mobile systems by their unique properties,
e. g. unpredictable nodal location, unstable topology and multi-hop packet relay. The
success of on-going research in communications involving MANETs has encouraged their applications
in areas with stringent performance requirements such as the e-healthcare, e. g. to
connect them with existing systems to deliver e-healthcare services anytime anywhere. However,
given that the capacity of mobile devices is restricted by their resource constraints (e. g.
computing power, energy supply and bandwidth), a fundamental challenge in MANETs is how
to realize the crucial performance/Quality of Service (QoS) expectations of communications in
a network of high dynamism without overusing the limited resources.
A variety of networking technologies (e. g. routing, mobility estimation and connectivity
prediction) have been developed to overcome the topological instability and unpredictability
and to enable communications in MANETs with satisfactory performance or QoS. However,
these technologies often feature a high consumption of power and/or bandwidth, which makes
them unsuitable for resource constrained handheld or embedded mobile devices. In particular,
existing strategies of routing and mobility characterization are shown to achieve fairly
good performance but at the expense of excessive traffic overhead or energy consumption. For
instance, existing hybrid routing protocols in dense MANETs are based in two-dimensional organizations
that produce heavy proactive traffic. In sparse MANETs, existing packet delivery
strategy often replicates too many copies of a packet for a QoS target. In addition, existing
tools for measuring nodal mobility are based on either the GPS or GPS-free positioning systems,
which incur intensive communications/computations that are costly for battery-powered
terminals. There is a need to develop economical networking strategies (in terms of resource
utilization) in delivering the desired performance/soft QoS targets.
The main goal of this project is to develop new networking strategies (in particular, for
routing and mobility characterization) that are efficient in terms of resource consumptions while
being effective in realizing performance expectations for communication services (e. g. in the
scenario of e-healthcare emergency) with critical QoS requirements in resource-constrained
MANETs.
The main contributions of the thesis are threefold:
(1) In order to tackle the inefficient bandwidth utilization of hybrid service/routing discovery
in dense MANETs, a novel "track-based" scheme is developed. The scheme deploys
a one-dimensional track-like structure for hybrid routing and service discovery. In comparison
with existing hybrid routing/service discovery protocols that are based on two-dimensional
structures, the track-based scheme is more efficient in terms of traffic overhead (e. g. about 60%
less in low mobility scenarios as shown in Fig. 3.4). Due to the way "provocative tracks" are
established, the scheme has also the capability to adapt to the network traffic and mobility for
a better performance.
(2) To minimize the resource utilization of packet delivery in sparse MANETs where wireless
links are intermittently connected, a store-and-forward based scheme, "adaptive multicopy
routing", was developed for packet delivery in sparse mobile ad-hoc networks. Instead
of relying on the source to control the delivery overhead as in the conventional multi-copy
protocols, the scheme allows each intermediate node to independently decide whether to forward
a packet according to the soft QoS target and local network conditions. Therefore, the
scheme can adapt to varying networking situations that cannot be anticipated in conventional
source-defined strategies and deliver packets for a specific QoS targets using minimum traffic
overhead.
ii
(3) The important issue of mobility measurement that imposes heavy communication/computation
burdens on a mobile is addressed with a set of resource-efficient "GPS-free" soluti ons,
which provide mobility characterization with minimal resource utilization for ranging and signalling
by making use of the information of the time-varying ranges between neighbouring
mobile nodes (or groups of mobile nodes). The range-based solutions for mobility characterization
consist of a new mobility metric for network-wide performance measurement, two
velocity estimators for approximating the inter-node relative speeds, and a new scheme for
characterizing the nodal mobility. The new metric and its variants are capable of capturing the
mobility of a network as well as predicting the performance. The velocity estimators are used to
measure the speed and orientation of a mobile relative to its neighbours, given the presence of a
departing node. Based on the velocity estimators, the new scheme for mobility characterization
is capable of characterizing the mobility of a node that are associated with topological stability,
i. e. the node's speeds, orientations relative to its neighbouring nodes and its past epoch time.
iiiBIOPATTERN EU Network of Excellence (EU Contract 508803
Survey on Software Defined VANETs
Modern vehicles are equipped with a wide variety of sensors, onboard computers and different devices supporting navigation and communication. These systems aim the fulfillment of various demands on the improvement of traffic safety, traffic/route optimization, passenger, comfort, etc.
Inter-vehicle and vehicle-infrastructure communication plays an important role in this process, which resulted in the birth of Vehicular Ad-hoc Networks. In the first part of the article, the key ideas of VANETs and their communication types are presented, then the most important features of vehicular ad-hoc networks are discussed followed by typical application types and actual characteristic research directions. The second part of the article focuses on Software Defined Networking and its application possibilities in VANETs emphasizing the benefits they can
provide
Store and Haul: Improving Mobile Ad-Hoc Network Connectivity through Repeated Controlled Flooding
This work investigates the benefits and drawbacks of repeating controlled flooding at different intervals in mobile ad hoc networks (MANETs) to overcome episodic connectivity. Specifically, the thesis examines the efficiencies in repeating transmissions by quantifying the packet delivery ratio (PDR) and recording the resulting delays in different types of MANET scenarios. These scenarios mainly focus on partitions within the simulated networks by varying node density and mobility. The nodes store transmitted data and haul it across the MANET in the hope that it will come in range of a node that leads to the destination. A customized version of the Network Simulator 2 (ns-2) is used to create the simulations. A qualitative analysis follows and shows the cost and benefits of increased transmissions at varied time intervals
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