I would suggest ns3 and castalia.

ns3 is new one simulator which has more functionality than ns2

Mannasim–A sensor Network Simulator for NS2

I will recommend NS3 because of very strong community and easy to understand

i have ns2 installed in my system so should i until it and need to install ns3?

I may suggest u NS3 as other mentioned

okay sir thanks to everyone.

Please see our paper "Evaluation of QoS Metrics in Ad Hoc Networks with the use of Secure Routing Protocols", indicated in the link below:

https://www.researchgate.net/publication/220707537_Evaluation_of_QoS_Metrics_in_Ad_Hoc_Networks_with_the_use_of_Secure_Routing_Protocols

An ad hoc network is formed by mobile computers (nodes) with wireless interfaces that communicate amongst themselves without the help of any infrastructure. Due to their characteristics, the ad hoc networks are prone to the presence of malicious nodes that can degrade the performance. This fact motivated the appearance of security protocols that implement mechanisms to avoid attacks like DoS. This article accomplished a verification of the impact caused in the performance of the ad hoc networks with the use of security protocols (SEAD and Ariadne) in relation to the use of protocols that don't have security mechanisms (DSDV and DSR). First an ad hoc network is simulated using these routing protocols and soon afterwards a comparative study is accomplished through graphs of the values obtained for each basic QoS metrics...

Conference Paper Evaluation of QoS Metrics in Ad Hoc Networks with the use of...

you can do it in ns2 itself just by adding few more script to the existing simulator

I will also recommend NS3 , you can refer the presentation 

Overview of NS3

http://www.slideshare.net/rahulhada/ns3-overview

NS3- Development Environment

http://www.slideshare.net/rahulhada/1-session-installation

Building Topilogy

http://www.slideshare.net/rahulhada/building-topology-in-ns3

Bundle of thanks to everyone who answer my question...i hope your suggestion will help me alot.

In fact, it depends on what kind of privacy preservation problem you want to solve. NS-2 only provides basic network support environment, may not necessarily suitable for the simulation. 

Sir,Hang!i am working on source location privacy preservation in wireless sensor networks,,so please recommend me the best simulator which is easy to use for simulation.

NS-2 is more suitable for the simulation data-communication-like applications. So, I think you can consider using MATLAB.

okay sir bundle of thanks to all of you specially Sir Hang Shen.

how about data privacy preserving in IoT. Which simulator do you suggest preferably visualized and handy

Hello Mehdi, You could try NetSim (https://www.tetcos.com) and it is probably the best tool currently for IOT