An ad hoc network is a collection of wireless mobile nodes dynamically forming a temporary network without the use of any existing network infrastructure or centralized administration. Due to the limited transmission range of wireless network interfaces, multiple network "hops " may be needed for one node to exchange data with another across the network. In recent years, a variety of new routing protocols targeted specifically at this environment have been developed, but little performance information on each protocol and no realistic performance comparison between them is available. This paper presents the results of a detailed packet-level simulation comparing four multi-hop wireless ad hoc network routing protocols that cover a range of design choices: DSDV, TORA, DSR, and AODV. We have extended the ns-2 network simulator to accurately model the MAC and physical-layer behavior of the IEEE 802.11 wireless LAN standard, including a realistic wireless transmission channel model, and present the results of simulations of networks of 50 mobile nodes. 1

In this paper we evaluate several routing protocols for mobile, wireless, ad hoc networks via packet level simulations. The ad hoc networks are multi-hop wireless networks with dynamically changing network connectivity owing to mobility. In the protocol suite includes several routing protocols specifically designed for ad hoc routing, as well as more traditional protocols, such as link state and distance vector, used for dynamic networks. Performance is evaluated with respect to fraction of packets delivered, end-to-end delay and routing load for a given traffic and mobility model. Both small (30 nodes) and medium sized (60 nodes) networks are used. It is observed that the new generation of on-demand routing protocols use much lower routing load, especially with small number of peer-to-peer conversations. However, the traditional link state and distance vector protocols provide, in general, better packet delivery and end-to-end delay performance. 1 Introduction A mobile, ad hoc networ...

Ad hoc networking allows hosts to communicate without the benefit of fixed infrastructure.

Routing in wireless ad hoc networks of mobile nodes is complicated by the fact that the transmission ranges and the communication bandwidth is limited, and that the network topology is highly dynamic due to continuously moving nodes. In this paper, a new approach is presented to equip proactive distance-vector routing algrithms with the capability of using multiple paths to each target. The basic idea of our multipath routing proposal is to split up a path between a source and a target node into two paths at every forwarding node. In contrast to other multipath approaches, our solution uses already available topology information and thus does not require any additional routing messages to be sent. The benefits of our approach with respect to load distribution, bottleneck avoidance, fairness and communication breakdowns are demonstrated via simulations.

The area of mobile ad hoc networking has received considerable attention of the research community in recent years. These networks have gained immense popularity primarily due to their infrastructure-less mode of operation which makes them a suitable candidate for deployment in emergency scenarios like relief operation, battlefield etc., where either the pre-existing infrastructure is totally damaged or it is not possible to establish a new infrastructure quickly. However, MANETs are constrained due to the limited transmission range of the mobile nodes which reduces the total coverage area. Sometimes the infrastructure-less ad hoc network may be combined with a fixed network to form a hybrid network which can cover a wider area with the advantage of having less fixed infrastructure. In such a combined network, for transferring data, we need base stations which act as gateways between the wired and wireless domains. Due to the hybrid nature of these networks, routing is considered a challenging task. Several routing protocols have been proposed and tested under various traffic conditions. However, the simulations of such routing protocols usually do not consider the hybrid network scenario. In this work we have carried out a systematic performance study of the two prominent routing protocols: Destination Sequenced Distance Vector Routing (DSDV) and Dynamic Source Routing (DSR) protocols in the hybrid networking environment. We have analyzed the performance differentials on the basis of three metrics – packet delivery fraction, average end-to-end delay and normalized routing load under varying pause time with different number of sources using NS2 based simulation.