Wednesday, March 10, 2010

HOWTO make and use a new application

How you go about making changes to components in large systems like ns-3 can seriously affect the level of happiness and stress in your life. So far we've taken an existing application and done nothing to it but change names. Even after this minor change, we observed that the application worked exactly as expected. This is a generic strategy. Take as much existing code as possible and then make small changes, stopping to make sure it all still works as much as possible. Although this may seem silly at first, it allows you to get your feet wet in a large system without getting into a state where you have no idea what is wrong and no idea how to find and fix the problem. This is not a pleasant place to be.

Good Luck !

Monday, March 8, 2010

An Improved IEEE 802.16 WiMAX Module for the ns-3 Simulator

Abstract: 

IEEE 802.16 WiMAX is a promising new wireless technology for providing broadband ubiquitous network access. As more and more researchers and industrials are interested in simulating such networks, a number of WiMAX simulators have been emerged in the networking community. One of the most recent WiMAX simulator is the one developed for ns-3. This module provides a standard compliant and well designed implementation of the standard and benefits from the major enhancements provided by ns-3 (compared to other network simulators) which has all the capabilities of becoming the leading network simulator in near future. However, this WiMAX module still lacks some important features which motivated this work. In this paper, we first provide a snapshot of existing WiMAX simulators available in the public domain, while highlighting their limitations. Then, we describe the new features and enhancements we have integrated within the ns-3 WiMAX module, and in particular: a realistic and scalable physical model, an IP packet classifier for the convergence sub-layer, efficient uplink and downlink schedulers, support for multicast traffic and pcap packet tracing functionality. The new design of the physical layer has improved the simulation time by several magnitude orders while still providing a realistic implementation of the standard. Furthermore, the IP classifier has enabled the simulation of an unlimited number of service flows per subscriber station, while the proposed schedulers improve the management of the QoS requirements for the different service flows.