Barun Saha's blog on AI and Networks

Conceptual architecture of SeeR Opportunistic Mobile Networks (OMNs) are characterized by intermittent connectivity among nodes. In many scenarios, the nodes attempt at local decision making based on greedy approaches, which can result in getting trapped at local optimum. Moreover, for efficient routing, the nodes often collect and exchange lot of information about others. To alleviate such issues, we present SeeR, a simulated annealing-based routing protocol for OMNs. In SeeR, each message is associated with a cost function, which is evaluated by considering its current hop-count and the average aggregated inter-contact time of the node. A node replicates a message to another node, when the latter offers a lower cost. Otherwise, the message is replicated with decreasing probability. Moreover, SeeR works based solely upon local observations. In particular, a node does not track information about other nodes, and, therefore, reduces the risk of privacy leaks unlike m...

Opportunistic Mobile Networks: Advances and Applications is our forthcoming textbook to be published by Springer in 2016. This book is a result of our years of experience in research and development in this domain. #TheOMNBook, if you may say, deals with fundamental challenges in OMNs as well as contemporary research issues. These include, but not limited to, routing, mobility, cooperation, heterogeneity, and emotions. An entire chapter is dedicated to protocol development and testing using the ONE simulator. #TheOMNBook is shaped in a way to cater both beginning and advanced level readers. Contextual examples are provided to ensure better understanding of related topics. The chapters come with plenty of hands-on exercises. Several illustrations and other visual elements are used to make reading the book a pleasant experience. Whether you are a seasoned researcher looking for novel cross-dimensional ideas or a beginner to this field, give #TheOMNBook a try! Learn more about our...

One of the frequently asked questions in the community is how to specify which particular nodes would act as source(s) and destination(s) of the messages created in the ONE simulator. The simulator, in fact, provides a pair of settings (shown below in bold face) aimed for this particular purpose. Let us consider that there are $n + 1$ nodes in an OMN.  Further, let the nodes with addresses from $x$ to $y$, both inclusive, would create messages. The nodes in the range $w$ to $z$, both inclusive, would be the destinations of those messages, where $0 \le x \le y \le n$, and $0 \le w \le z \le n$. Then, the corresponding simulation scenario can be configured as follows. ## Message creation parameters # How many event generators Events.nrof = 1 # Class of the first event generator Events1.class = MessageEventGenerator # (Following settings are specific for the MessageEventGenerator class) # Creation interval in seconds (one new message every 25 to 35 seconds) Events1.interval ...

The DTN blog recently reached a milestone — it crossed 50,000 page views! The journey of this blog — and that of mine with the ONE simulator — started in 2011. Back in those days, old-timers would recall, there were not much resources available on the ONE simulator. After spending some time with it, I was finally able to gain some understanding about its functionality and work flow. I realized that a short how-to document might benefit others. What started as a humble effort to provide a quick tutorial on the ONE simulator soon became a popular resource in the community over the years. I'm thankful to all the users of the ONE mailing list who continuously kept me motivated to enrich this blog. I took this opportunity to prepare an infographic on the usage of the DTN blog based on the statistics provided by Blogger. It has not been possible to include all statistics in the infographic. A few interesting observations are noted below. Undoubtedly, the ONE tutorial is the mos...

Recently ns2web had suffered some downtime. However, it is up and running once again. Any inconvenience caused is regretted. If you are working with NS-2, you may try out the remote simulation and online analysis feature of ns2web . Also, read the article in IEEE Wireless Communications magazine on ns2web.

In this post, we look at how buffer size affects, if at all, the performance of the routing protocols in DTNs. For this purpose, we will consider the following five routing protocols: Epidemic PROPHET Spray-and-Wait (SnW) First Contact (FC) Direct Delivery (DD)  Detailed discussion of these protocols is scoped out here. We just note that in case of Epidemic, there is unlimited replication of the messages. In PROPHET, however, the replication is usually less than that of Epidemic. On the other hand, SnW has a fixed limit ( L ) on possible number of replications of a message. Finally, FC and DD involve message forwarding -- not replication. So, in the latter cases, there is always a single copy of any message in the DTN. We will consider the buffer sizes from 20 MB to 180 MB, both inclusive, in steps of 20 MB so that we have total 9 different buffer sizes. We will use the real-life connection traces from Infocom'06. Therefore, we will need to simulate 5 * 9 = 45 scenarios...

In my previous articles, I have discussed about the Virtual Labs and IEEE WCM Feature Article on ns2web . Today, I would briefly discuss about ns2web with specific focus on one of its more general features -- data plotting utility. Ns2web is the core component of the Advanced Network Technology Virtual Labs. At a high level it has two basic jobs to perform: Execute the NS-2 simulations in a remote server based on the user input code. Help users perform different types of post-simulation analysis using the trace file generated. As such, ns2web itself becomes a sort of mini-project :) Currently, ns2web and the version of it used with the ANT VLab differ on a few minor aspects. The former offers a ``guided scenario generator'' to the users, and an option to export the graphs as external images. However, ns2web is not only for performing network simulations! The software provides a useful feature that might interest you if you want to quickly plot some nice line plots...

The article " A Web-Based Integrated Environment for Simulation and Analysis with NS-2 " appeared as a "Feature Article" in the August 2013 issue of the IEEE Wireless Communications Magazine ( archived URL ). The article presented the design and implementation of a Web-based environment to enable remote network simulations using NS-2, and subsequent analysis using the trace file generated. Plots obtained from the simulation results (as well as, their corresponding data) can be exported as EPS/PDF/PNG files, which helps in using them with research articles. URL of ns2web : http://vlssit.iitkgp.ernet.in/ns2web/ns2web/

A new post on parametrized simulations with the ONE in batch mode is available now: http://delay-tolerant-networks.blogspot.com/p/parametrized-simulations.html This explains how to run multiple scenarios in batch mode considering different parameters.

The Virtual Labs project was launched a year ago.  Currently, these labs are undergoing user trials. I have been involved with the development of two virtual labs -- Software Engineering (cse08) and Advanced Network Technologies (cse28) . Interested users may visit these labs. It would be further useful if you could provide feedback on one or more experiments. The feedback link is available in the navigation bar at the top.