2,131 research outputs found
Improving Energy Efficiency in MANETs by Multi-Path Routing
Some multi-path routing algorithm in MANET, simultaneously send information
to the destination through several directions to reduce end-to-end delay. In
all these algorithms, the sent traffic through a path affects the adjacent path
and unintentionally increases the delay due to the use of adjacent paths.
Because, there are repetitive competitions among neighboring nodes, in order to
obtain the joint channel in adjacent paths. The represented algorithm in this
study tries to discover the distinct paths between source and destination nodes
with using Omni directional antennas, to send information through these
simultaneously. For this purpose, the number of active neighbors is counted in
each direction with using a strategy. These criterions are effectively used to
select routes. Proposed algorithm is based on AODV routing algorithm, and in
the end it is compared with AOMDV, AODVM, and IZM-DSR algorithms which are
multi-path routing algorithms based on AODV and DSR. Simulation results show
that using the proposed algorithm creates a significant improvement in energy
efficiency and reducing end-to-end delay
Single failure resiliency in greedy routing
Using greedy routing, network nodes forward packets towards neighbors which are closer to their destination. This approach makes greedy routers significantly more memory-efficient than traditional IP-routers using longest-prefix matching. Greedy embeddings map network nodes to coordinates, such that greedy routing always leads to the destination. Prior works showed that using a spanning tree of the network topology, greedy embeddings can be found in different metric spaces for any graph. However, a single link/node failure might affect the greedy embedding and causes the packets to reach a dead end. In order to cope with network failures, existing greedy methods require large resources and cause significant loss in the quality of the routing (stretch loss). We propose efficient recovery techniques which require very limited resources with minor effect on the stretch. As the proposed techniques are protection, the switch-over takes place very fast. Low overhead, simplicity and scalability of the methods make them suitable for large-scale networks. The proposed schemes are validated on large topologies with properties similar to the Internet. The performances of the schemes are compared with an existing alternative referred as gravity pressure routing
Providing protection in multi-hop wireless networks
We consider the problem of providing protection against failures in wireless networks subject to interference constraints. Typically, protection in wired networks is provided through the provisioning of backup paths. This approach has not been previously considered in the wireless setting due to the prohibitive cost of backup capacity. However, we show that in the presence of interference, protection can often be provided with no loss in throughput. This is due to the fact that after a failure, links that previously interfered with the failed link can be activated, thus leading to a “recapturing” of some of the lost capacity. We provide both an ILP formulation for the optimal solution, as well as algorithms that perform close to optimal. More importantly, we show that providing protection in a wireless network uses as much as 72% less protection resources as compared to similar protection schemes designed for wired networks, and that in many cases, no additional resources for protection are needed.National Science Foundation (U.S.) (Grant CNS-1116209)National Science Foundation (U.S.) (Grant CNS-0830961)United States. Defense Threat Reduction Agency (Grant HDTRA-09-1-005)United States. Air Force (Contract FA8721-05-C-0002
Local heuristic for the refinement of multi-path routing in wireless mesh networks
We consider wireless mesh networks and the problem of routing end-to-end
traffic over multiple paths for the same origin-destination pair with minimal
interference. We introduce a heuristic for path determination with two
distinguishing characteristics. First, it works by refining an extant set of
paths, determined previously by a single- or multi-path routing algorithm.
Second, it is totally local, in the sense that it can be run by each of the
origins on information that is available no farther than the node's immediate
neighborhood. We have conducted extensive computational experiments with the
new heuristic, using AODV and OLSR, as well as their multi-path variants, as
underlying routing methods. For two different CSMA settings (as implemented by
802.11) and one TDMA setting running a path-oriented link scheduling algorithm,
we have demonstrated that the new heuristic is capable of improving the average
throughput network-wide. When working from the paths generated by the
multi-path routing algorithms, the heuristic is also capable to provide a more
evenly distributed traffic pattern
QoS in Node-disjoint Routing for Ad Hoc Networks
PhDA mobile ad hoc network (MANET) is a collection of mobile nodes that
can communicate with each other without using any fixed infrastructure.
It is necessary for MANETs to have efficient routing protocol and quality
of service (QoS) mechanism to support multimedia applications such as
video and voice.
Node-Disjoint Multipath Routing Protocol (NDMR) is a practical protocol
in MANETs: it reduces routing overhead dramatically and achieves
multiple node-disjoint routing paths.
Because QoS support in MANETs is important as best-effort routing is
not efficient for supporting multimedia applications, this thesis presents a
novel approach to provide that support.
In this thesis NDMR is enhanced to provide a QoS enabled NDMR that
decreases the transmission delay between source and destination nodes.
A multi-rate mechanism is also implemented in the new protocol so that
the NDMR QoS can minimise the overall delays. It is shown that these
approaches lead to significant performance gains. A modification to
NDMR is also proposed to overcome some of the limitations of the
original
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