5,994 research outputs found
A Distributed Geo-Routing Algorithm for Wireless Sensor Networks
Geographic wireless sensor networks use position information for greedy routing. Greedy routing works well in dense networks, whereas in sparse networks it may fail and require a recovery algorithm. Recovery algorithms help the packet to get out of the communication void. However, these algorithms are generally costly for resource constrained position-based wireless sensor networks (WSNs). In this paper, we propose a void avoidance algorithm (VAA), a novel idea based on upgrading virtual distance. VAA allows wireless sensor nodes to remove all stuck nodes by transforming the routing graph and forwarding packets using only greedy routing. In VAA, the stuck node upgrades distance unless it finds a next hop node that is closer to the destination than it is. VAA guarantees packet delivery if there is a topologically valid path. Further, it is completely distributed, immediately responds to node failure or topology changes and does not require planarization of the network. NS-2 is used to evaluate the performance and correctness of VAA and we compare its performance to other protocols. Simulations show our proposed algorithm consumes less energy, has an efficient path and substantially less control overheads
1-D Coordinate Based on Local Information for MAC and Routing Issues in WSNs
More and more critical Wireless Sensor Networks (WSNs) applications are
emerging. Those applications need reliability and respect of time constraints.
The underlying mechanisms such as MAC and routing must handle such
requirements. Our approach to the time constraint problem is to bound the
hop-count between a node and the sink and the time it takes to do a hop so the
end-to-end delay can be bounded and the communications are thus real-time. For
reliability purpose we propose to select forwarder nodes depending on how they
are connected in the direction of the sink. In order to be able to do so we
need a coordinate (or a metric) that gives information on hop-count, that
allows to strongly differentiate nodes and gives information on the
connectivity of each node keeping in mind the intrinsic constraints of WSWs
such as energy consumption, autonomy, etc. Due to the efficiency and
scalability of greedy routing in WSNs and the financial cost of GPS chips,
Virtual Coordinate Systems (VCSs) for WSNs have been proposed. A category of
VCSs is based on the hop-count from the sink, this scheme leads to many nodes
having the same coordinate. The main advantage of this system is that the hops
number of a packet from a source to the sink is known. Nevertheless, it does
not allow to differentiate the nodes with the same hop-count. In this report we
propose a novel hop-count-based VCS which aims at classifying the nodes having
the same hop-count depending on their connectivity and at differentiating nodes
in a 2-hop neighborhood. Those properties make the coordinates, which also can
be viewed as a local identifier, a very powerful metric which can be used in
WSNs mechanisms.Comment: (2011
Jumps: Enhancing hop-count positioning in sensor networks using multiple coordinates
Positioning systems in self-organizing networks generally rely on
measurements such as delay and received signal strength, which may be difficult
to obtain and often require dedicated equipment. An alternative to such
approaches is to use simple connectivity information, that is, the presence or
absence of a link between any pair of nodes, and to extend it to hop-counts, in
order to obtain an approximate coordinate system. Such an approximation is
sufficient for a large number of applications, such as routing. In this paper,
we propose Jumps, a positioning system for those self-organizing networks in
which other types of (exact) positioning systems cannot be used or are deemed
to be too costly. Jumps builds a multiple coordinate system based solely on
nodes neighborhood knowledge. Jumps is interesting in the context of wireless
sensor networks, as it neither requires additional embedded equipment nor
relies on any nodes capabilities. While other approaches use only three
hop-count measurements to infer the position of a node, Jumps uses an arbitrary
number. We observe that an increase in the number of measurements leads to an
improvement in the localization process, without requiring a high dense
environment. We show through simulations that Jumps, when compared with
existing approaches, reduces the number of nodes sharing the same coordinates,
which paves the way for functions such as position-based routing
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