23-07-2012, 02:20 PM
Measurement Based Performance of Reactive and Proactive Routing Protocols in WMN
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INTRODUCTION
Wireless Mesh Networks have emerged as a key technology for next-generation wireless networking. WMNs is the key technology for represent an emerging wireless networking technology that promises wider coverage than traditional wireless LANs and lower development and operation cost than 3G cellular networks. The most commonly used technology in day to day life is desktops, laptops, PDA’s, Pocket PC’s, Phones. WMNs can also be used in other applications such as broadband, networking, enterprise networking building automation, and neighbourhood networks. Although by definition a WMN is any wireless network having a network topology of either a partial or full mesh topology, practical WMNs are characterized by static wireless relay nodes providing a distributed infrastructure for mobile client nodes over a partial mesh topology.
ANALYSIS OF REACTIVE ROUTING PROTOCOLS
In reactive routing protocols, the route is calculated only when a node needs to send data to an unknown destination. Thus, route discovery is initiated only when needed. This saves overhead in maintaining unused routes. However, this may lead to larger initial delays. During route discovery, the query is flooded into the entire network and the reply from the destination (or intermediate nodes) sets up the path between the source and destination. The Reactive protocols are classified into Ad-hoc on Demand Distance Vector, Dynamic Source Routing, SRCRR, Link Quality Source Routing, and Multi radio Link Quality Source Routing.
DSR Routing Protocol
Dynamic source routing protocol (DSR) is a reactive protocol (on demand routing protocol) that is known as simple and efficient, specially designed for the multi-wireless mesh network. Often called ―on-demand‖ routing protocol as it involves determining the routing on demand unlike the pro- active routing protocols that has periodic network information. This means that it discovers the route from source to the destination if required. DSR was designed to restrict the bandwidth consumed by control packets in ad hoc wireless networks, by eliminating the periodic table-update messages used in proactive protocols. DSR protocol is based on two mechanisms: route discovery and route maintenance.
Ad-hoc on Demand Distance Vector
Ad-hoc on Demand Distance Vector routing protocol is developed as an improvement to DSDV routing algorithm. The purpose of DSDV is to reduce the number of broadcast messages sent throughout the network and reduces the routing overhead, but introduces some initial latency due to the on demand route setup. This is achieved by discovering routes on-demand instead of keeping complete up-to-date route information. AODV uses a simple request–reply mechanism for the discovery of routes. AODV protocol mainly involves 3 packets. They are [7]:
Multi radio Link Quality Source Routing
A new routing protocol for multi-radio multi-channel WMNs called Multi-Radio Link Quality Source Routing. Multi radio Link Quality Source Routing also a reactive routing protocol for wireless mesh networks. MR-LQSR is a combination of the LQSR protocol [13] with a new metric that we call WCETT. LQSR is a source-routed link-state protocol derived from DSR [14]. A link-state protocol consists of four components: