NS-3 has been one of the popular network simulator software for many years especially in research related to Mobile Adhoc Networks (MANETs). In NS-3, there is provision of several mobility models including Random Waypoint (RWP) mobility model and Steady State Random Waypoint (SSRWP) mobility model. RWP mobility model suffers from the transition phase related imperfection. SSRWP mobility model overcomes this limitation of RWP mobility by allowing the steady state initialization states of nodes in terms of position, speed and pause time of mobile nodes right from the beginning of the simulation. As SSRWP mobility model avoids any requirement of warm-up (cut-off) phase of RWP mobility model, it saves a significant amount of time of warm-up (cut-off) phase as well as establishes a high level of confidence in results obtained due to absence of any subjective guess. In the present work, RWP and SSRWP mobility models have been investigated using AODV routing protocol and it has been found that a way to mitigate the misleading effect of the transition phase of RWP mobility model is to have a sufficiently large simulation time which results, to a good extent, in convergence of performance of RWP mobility model toward that of SSRWP mobility model.

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As security is a very challenging issue in ad hoc networks, variety of research works related to security of ad hoc networks are being reported for last many years. In the present work, we propose a new sort of attack titled Twin-Node Neighbour Attack (TNNA), wherein two malicious nodes in close vicinity of each other exploits the provision of broadcast nature of Hello Messages in AODV routing protocol along with non-provision of any restriction regarding authentication of participating nodes. Mitigation measures are designed to lessen or perhaps remove security flaws and threats altogether. Detection and mitigation of TNNA attack are also proposed and discussed. The network's performance has been measured using four metrics viz. Packet Delivery Ratio, Throughput, Total Number of Received Packets and Average End-toEnd Delay. It is evident from simulations that the TNNA attack is significantly detrimental to the performance of WANETs using AODV routing protocol. After attack throughput of legitimate flow is found to be less than 5 % as compared to the Throughput without attack, when the data rate of malicious node is 100 Kibps. Due to stress of malicious flow of 100 Kibps, the number of transmitted (received) data packets of legitimate flow is reduced by a factor of more than 20.

AODV is a reactive routing protocol that sets up routes between source and destination nodes as and whenneeded. The performance of AODV protocol depends on the choice of certain parameters including route requestretries which is, by default, set as two in the corresponding RFC. In the present work, the effect of Route RequestRetries (RRR) on a set of performance metrics viz. Normalized Routing Load (NRL), Average End-to-End Delay(AEED), Packet Delivery Ratio (PDR) and Throughput has been investigated for a linear ad hoc network of fivenodes. Three different scenarios have been investigated wherein middle node is made to remain stationary, mobilewith low mobility and mobile with high mobility. Mobility of the middle node is found to be having significanteffect on the performance of such linear ad hoc networks. RRR has no influence on the performance of linear adhoc network of stationary nodes. However, RRR is having significant effect on the performance of linear ad hocnetwork if a node is made mobile. Performance of such linear ad hoc network is also affected by the choice ofduration of simulation.

The node deployment technique in Mobile Ad Hoc networks plays a vital role in the evaluation of a routing protocol. In this paper, the performance of Ad Hoc On-Demand Distance Vector (AODV) routing protocol has been investigated using Uniform and Random Disc Position Allocators offered by NS-3 as Initial Position Allocator as well as Next Position Allocator along with random waypoint mobility model. The simulation results exhibit that AODV routing protocol performs better in case of random disc position allocator as compared to uniform disc position allocator where performance metrics are taken as the Average End-to-End Delay, Throughput and Packet Delivery Ratio.