Satellite Network Simulation In NS

Hi,
 This post is to show how we can simulate a satellite network in Network Simulator. Some extensions can enable ns to model;

1. Traditional geostationary ``bent-pipe'' satellites with multiple users per uplink/downlink and asymmetric links.
2. Geostationary satellites with processing payloads (either regenerative payloads or full packet switching).
3. Polar orbiting LEO constellations such as Iridium and Teledesic. 

These satellite models are principally aimed at using ns to study networking aspects of satellite systems; in particular, MAC, link layer, routing, and transport protocols.

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INTERNET BASED EFFICIENT CONTENT DISTRIBUTION PROTOCOL FOR MANET

Torrent is one of the Internet's most efficient content distribution protocols. It is known to perform very well over the wired Internet where end-to-end performance is almost guaranteed. However, in wireless ad hoc networks many constraints appear as the scarcity of resources and their shared nature, which make running BitTorrent with its default configuration not lead to best performances. To these constraints it adds the fact that peers are both routers and end-users and that TCP-performance drops seriously with the number of hops. We show in this work that the neighbor selection mechanism in BitTorrent plays an important role in determining the performance of the protocol when deployed over a wireless ad hoc network. It is no longer efficient to choose and treat with peers independently of their location. A first solution is to limit the scope of the neighborhood. In this case, TCP connections are fast but there is no more diversity of pieces in the network: pieces propagate in a unique direction from the seed to distant peers. This prohibits peers from reciprocating data and leads to low sharing ratios and sub optimal utilization of network resources. To recover from these impairments, we propose an enhancement to torrent which aims to minimize the time to download the content and at the same time to enforce cooperation among peers. Our solution considers a restricted neighborhood to reduce routing overhead and to improve throughput, while establishing few connections to remote peers to improve diversity of pieces. With the help of extensive NS-2 simulations, we show that these enhancements to Torrent significantly improve the file completion time while fully profiting from the incentives implemented in Torrent to enforce fair sharing.

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ADAPTIVE POLLING ALGORITHM FOR WLAN [NS2 IMPLEMENTATION]

IEEE 802.11 PCF mode is defined to support time bounded applications in wireless LANs. The poll scheduling plays an important role in PCF mode operation. It differs from the packet scheduling of routers in that incomplete queueing information in each pollable station is known to the scheduler. This paper proposes an adaptive polling algorithm to improve the wireless medium utilization. In our scheme, each mobile station is assigned a priority by the point coordinator. Based on recent poll feedbacks, the priority for each mobile station will be dynamically updated using the Additive Increase/Multiplicative Decrease algorithm. The proposed polling algorithm is compatible with the IEEE 802.11 standard and requires a simple extension. our simulation studies show that the performance of wireless LANs are improved in terms of the successful poll rate and the aggregate throughput.

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NSG 2.1 - THE TCL SCRIPT GENERATOR

NS2 Scenarios Generator (NSG) is a tcl script generator tool used to generate TCL Scripts automatically . . . !!!

NSG is a Java based tool that runs on any platform and can generate TCL Scripts for Wired as well as Wireless Scenarios for Network Simulator - 2. The procedure to execute these TCL Scripts on NS-2 is same as those of manually written TCL Scripts.

Some of the main features of NS2 Scenarios Generator (NSG) are as mentioned below:

(1) Creating Wired and Wireless nodes just by drag and drop.
(2) Creating Simplex and Duplex links for Wired network.
(3) Creating Grid, Random and Chain topologies.
(4) Creating TCP and UDP agents. Also supports TCP Tahoe, TCP Reno, TCP New-Reno and TCP Vegas.
(5) Supports Ad Hoc routing protocols such as DSDV, AODV, DSR and TORA.
(6) Supports FTP and CBR applications.
(7) Supports node mobility.
(8) Setting the packet size, start time of simulation, end time of simulation, transmission range and interference     range in case of wireless networks, etc.
(9) Setting other network parameters such as bandwidth, etc for wireless scenarios.

The Snapshots of NSG is as shown below:

 

 

Download NSG2 :

NSG2 (2007/5/20)

NSG2.1 (2008/11/18)

If you still wanna download NSG1 (previous version of NSG), it can be found here.

To execute NSG you need to install Java 6.0. NSG does not require any installation . . . !!! Just double click on the jar file to launch NSG. If it does not work, please see the instructions provided on the homepage of NSG here.

For more information on NSG and its previous versions, please visit the homepage of NSG here.

Launch NSG2 :

To execute NSG2, you have to install JAVA6.0 first. You can download JAVA6.0 from http://java.sun.com/. The details of JAVA6.0 installation, please refer to Sun JAVA site.

NSG2 doesn't need to be installed in your computer. You just download it and launch it with following instruction under TERMINAL command environment. 
In fact, on my computer system, Ubuntu 12.04 I just double click the NSG2.jar, and NSG2 will automatically launch. If it doesn't launch, you can also launch NSG2 as following instructions.

• open terminal
• change directory into the folder where NG2.1.jar is copied.
• type this cammand
  java -jar NSG2.1.jar

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