SNR-Based OLSR Routing Protocol for Wireless Mesh Networks

Wireless Mesh Networks (WMNs) consist of a collection of mobile and fixed nodes that
form a network. Nodes are capable of communicating with each other either with
infrastructure, or infrastructureless, or in a hybrid mode. The major advantages of WMNs
over the other wireless networks are the low-cost, self organization, self configuration,
last mile internet solution, scalability, and reliability. These advantages have attracted the
researcher over the last five years. WMNs technology is gaining an increased attention
from the Institute of Electrical and Electronics Engineers (IEEE) community. This led the
IEEE organization to emerge a special working group (IEEE 802.11s) in charge of the
issues deriving from a completely wireless distribution system used to interconnect
different Basic Service Sets (BSSs) through secure and performing links.
In a multi-hop networks, like WMN, one of the main factors that influences the
performance is the routing protocol. Generally speaking, routing protocols can be
classified based-on the routing metric to 1) hop count-based routing protocols, like Adhoc
on demand distance vector (AODV) where the optimum path is defined as the path
that goes through the minimum number of nodes, 2) the link quality-based routing
protocols, like OLSR where some metrics such as the bandwidth and the packet error rate
are considered to define the optimum path to the destination.
In this work the performances of a three commonly used routing protocols are compared.
The main goal of this stag is to study the influence of different routing protocols in
WMNs. The comparison is conducted with two scenarios of networks; a high mobility network and a low mobility network. (Open network) OPNET 11.5 modeler is used to
build the WMNs. The performance of the network and the routing protocols has been
studied in means of network throughput, End-to-End delay, routing protocol overhead
and the mobility. The obtained results show that the Optimized link state routing protocol
(OLSR) has the highestthroughput overDSR andAODVrouting protocols in WMNs.
The unpredictable behavior of the wireless medium in WMNs environment demands the
need for a routing protocol that is aware of the link conditions. Unfortunately the routing
protocols used such as AODV and Dynamic source routing (DSR) are hop count-based;
where the routing algorithm uses the number of nodes to determine the optimum path to
the destination.
In the second stage of this work a new routing technique for WMNs based-on Signal to
noise ratio (SNR) as a new metric for OLSR routing protocol, is developed. The new
metric has been implemented on the OLSR routing protocol module using OPNET
simulator. The modified OLSR routing protocol is implemented in the comparison
scenarios. The obtained results show that, when SNR is used as a routing metric in the
OLSR routing protocol, the OLSR is getting the significantly higher network throughput
over the DSR and AODV routing protocols. In the same time, the modified OLSR
implemented with the SNR metric is showing a high improvement over the OLSR with
the traditional hop-count metric. This thesis also studies the affect of different amounts of
mobility in WMNs performance.
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