## Posts

Showing posts from 2014

### Merry Christmas and Happy Holidays

Wish you all a Merry Christmas! Have a happy and fun-filled holiday season! And let us all hope to bring out our best in the coming New Year!

Cheers!

### Room Marker: Advertise and Search for Rental Rooms

Moving to a new city is hectic and finding a house there is often difficult. How about an app that let you locate rental houses in a city even before you move there?
Or perhaps you have a house (or some other property) that you want to rent out. How about an app that enable you reach to a vast set of target customers?

Recently, one of my friends launched Room Marker, a mobile app to reduce your woes. If you are a property owner, post you rental advertisements easily. If you are looking for renting a house, Room Marker is just the right app for you. Discover the houses available for rent in your neighborhood merely by a few taps on the screen.

The key features of Room Marker are:
Search for houses available for rent nearby your location — or at any other placeFilter your search based on multiple criteria (e.g., price range and property type) to narrow down your choicesAdvertise the rental property easilyAdvertise your property now, but pay laterTurn off advertisements when not re…

### Ns2web is up

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.

### Featured in Openshift Developer Spotlight

As many of you would know, a few months back I have launched the ONE Knowledge Base, which is hosted on Openshift. This week, my profile has been featured in the Openshift Developer Spotlight. Check out the mini-interview to learn why the ONE KB was developed and what problem it solves. Besides, you would also get to know about my favorite tools and development stack :)

If you have not tried the ONE KB yet, go for it now. Search the archives, and you might find that your question has already been answered!

### Controlling Transmission Range from within the Simulation

While simulating scenarios with the ONE simulator, one typically defines one or more network interfaces, and add them to the nodes as required. This use case prevails in most of the scenarios. However, a drawback here is that different network interfaces are mutually incompatible — an interface of type 1 can't communicate with any interface not of type 1.

Under certain circumstances, it might be required to control the transmission range of one or more network interfaces dynamically from within the simulation. For example, in one of my works, "On emotional aspects in Mission-Oriented Opportunistic Networks", I have considered the case where users occasionally turn off their device radios based on their contemporary emotions. In particular, the following shows how to set the radio range to 0: ModuleCommunicationBus comBus = host.getComBus(); // Store the original radio range the first time it is reset if (this.originalRadioRange == -1) { this.originalRadioRange = Double…

### The ONE Knowledge Base

The Opportunistic Network Environment (ONE) simulator has become largely popular and widely used in research on DTNs and Opportunistic Networks. The simulator has an associated friendly community, where users can ask questions and get their doubts clarified. Indeed, the community is vibrant and its members are useful. However, there are two issues with this community.

First, the archives of the community's mailing list are not public. This is unlike many other similar lists hosted using Mailman, which are public and, therefore, can be searched using Google. Hence, time and again people have asked the question -- how to search the email archives?

The second issue is largely due to the first. Due to the lack of searching facility over the archives, often same question tend to be asked by the new users repeatedly. People here are patient enough to reply to them. But such necessity could be entirely discounted had there been a facility to search the archives. In particular, it would b…

### Commonly Used Metrics for Performance Evaluation

The following metrics are commonly used when evaluating scenarios related to DTN protocols.
Delivery ratio of the messages,Average message delivery latencyOverhead ratio (of the underlying routing mechanism) Suppose that $M$ be the set of all messages created in the network and $M_d$ be the set of all messages delivered. Then, the delivery ratio is computed as $|M_d| / |M|$.

Now let the $i^{th}$ delivered message was created at time $c_i$ and delivered at time $d_i$. Then the average message delivery latency is computed as $(\sum_{i = 1}^{|M_d|} (d_i - c_i)) / |M_d|$. Note that, in Statistics, mean, median and mode are all the measures of average. But "loosely speaking", unless otherwise specified, we refer to the "mean" value when we say "average." Nevertheless, the MessageStatsReport in the ONE simulator provides a measure of both the mean and median values wherever appropriate.

One may refer the above metric as "end-to-end delay." Personally,…

### Effects of Buffer Size on Delay Tolerant Routing

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:
EpidemicPROPHETSpray-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 to get the rel…

### Discover Plotting Utility Within Ns2web

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.

As shown …