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Abstract
Routing in ad hoc network is a great problematic, since a good routing protocol must ensure fast and efficient packet forwarding, which isn’t evident in ad hoc networks. In
literature there exists lot of routing protocols however they don’t include all the aspects of ad hoc networks as mobility, device and medium constraints which make these protocols not efficient for some configuration and categories of ad hoc networks. Thus in this paper we propose an improvement of Dynamic Source Routing Protocol DSR in order to include some of the aspects of ad hoc networks as mobility and energy by proposing a new metric to evaluate route based on intermediate nodes weight computed by combining the stability an the battery power of nodes to choose the most stable and powered nodes for packet
forwarding.
The paper is organized into five parts, in the first ones we give an overview of ad hoc networks and routing protocols; and a brief presentation of DSR. However the rest of parts are consecrated for our proposed improvement for DSR and simulation results of Weight Based Dynamic Source Routing Protocol WDBSR finishing the paper by a conclusion and future extension of this work.
INTRODUCTION:
Mobile ad hoc network (MANET) are a collection of wireless mobile nodes forming a temporary network, using as transmission medium radio waves. The used specter for wireless transmissions is the specter situated around the 2.4 and around the 5 GHz .The transmission range and the emission power are regulated by laws in each country, ranging
from 10 m for Personal Area Networks to 100-200 m for Local Area Networks.
Regarding its costless, facility of use and deployment, MANET gets day after day new applications ranging from military applications for connecting soldiers in battlefields and
civil or commercial application such as Public and Personal Area Networks, other applications are recently under development will also benefit from MANETs advantages such as telemedicine, weather report and disaster environment such as in seism. All these examples of use predict for some envisioned MANETs to increase in size to reach the threshold of thousands of nodes per system (commercial or military). However in ad hoc network there is no concept of centralized administration, to manage some tasks as security, routing and others, therefore mobile nodes must collaborate among themselves to accomplish these services. However due to dynamic topology; the energy and the bandwidth constraints due to the nature of devices and the transmission medium;
these tasks are not easily carried out. Thus any developed protocol for ad hoc networks must take into consideration all the aspects of ad hoc networks as mobility, energy and
bandwidth constraints to develop an efficient and effective routing or security protocol.
In the remainder of this paper we are going to treat the aspect of routing by proposing an improvement of Dynamic Source Routing Protocol DSR to include some system parameters as a new metric for route evaluation, trying in this way to solve some of the problematic of ad hoc networks.
ROUTING IN AD HOC NETWORKS
In ad hoc networks, to ensure the delivery of a packet from sender to destination, each node relay on its neighboring nodes to forward packets to nodes which are not in its
transmission range. Therefore any node in the network plays two roles the first one as an ordinary node and the second one as a router. The problematic in ad hoc network is the dynamic topology of the network, resulting on a fast changing in routes which must be efficiently handled by the underlying routing protocol. Other problems exist due to the nature of nodes as energy and computing power must also be carried out by the routing protocol to ensure effective routing. Regarding the technique and the strategy of routing we can classify them into the following categories: reactive, proactive, and hybrid protocols.
A. Reactive protocols
Under a reactive protocol, topology information is given only when needed. Thus whenever a node wants to know the route to a destination, it floods the network with a route discovery request in order to get the sequence of nodes to the destination . This gives reduced average control traffic, and an additional delay due to the fact that the route is not
immediately available. The much known reactive protocol is DSR (Dynamic Source Routing), however they exist other like AODV (Ad hoc On-demand Distance Vector routing). These protocols have the inconvenient that they cause a great congestion during the process of discovering routes; however some protocols as DSR and DSDV have proven their efficiency for ad hoc networks.
B. Proactive protocols
Proactive protocols are characterized by periodic exchange of topology control messages, to update their routing tables. Therefore, control traffic is more dense but constant, and
routes are instantly available. Some examples of these kind of routing protocols are: OLSR (Optimized Link State Routing), OSPF (Open Shortest Path First) and FSR (Fisheye State Routing).
Theses protocols keep the network traffic within an acceptable threshold due to the maintain of routing tables; however when the topology changing is very frequent the
maintenance of routing table causes a great overhead due to the number of exchanged data, making them not desired for high mobility ad hoc networks.