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Pralhad DeshpandeComputer Science Department |
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I am a Ph.D. candidate in the Computer Science Department at Stony Brook University, Stony Brook. My research interests are broadly in the areas of wireless networks, protocol design, experimental systems and network measurements. My adviser is Prof. Samir Das. My dissertation work is on enabling efficient and cost effective wireless network access from moving vehicles. See my resume (short) and navigate through this page for details of my work. News: I have accepted employment at IBM Research, Bangalore and will be starting in August, 2012. TalksHonors and AwardsInternshipsPublicationsAlso see DBLP, Google scholar Pralhad Deshpande, Samir R. Das To appear in the proceedings of the Ninth ACM International Workshop on VehiculAr Inter-NETworking, Systems, and Applications (VANET 2012), Low Wood Bay, Lake District, United Kingdom, June 25, 2012. Short abstract: All rate adaptation algorithms in literature arrive at an estimate of the current channel conditions by considering the recent history often in the order of seconds. In vehicular WiFi access networks, the constantly changing wireless channel conditions make the channel history irrelevant quickly. We develop BRAVE: an SNR-based rate adaptation algorithm, which only considers short history (500 ms) to make rate selection decisions. In order to compare the algorithms under repeatable channel conditions, we develop and use a novel emulation methodology where a software radio based programmable noise generator is used to emulate varying link quality under vehicular mobility. Xiaoxiao Hou, Pralhad Deshpande, Samir R. Das In proceedings of the 19th IEEE International Conference on Network Protocols (ICNP 2011), Vancouver, BC Canada, October 17-20, 2011 Short abstract: We investigate a transport layer protocol design that integrates 3G and WiFi networks, specifically targeting vehicular mobility. The goal is to move load from the expensive 3G network to the less expensive WiFi network without hurting the user experience. As the test platform we choose a nationwide 3G network and a commercially operated metro-scale WiFi network. We exploit the often complementary characteristics of these networks for a hybrid design at the transport layer. Instead of simply striping data over two network connections, we develop a utility and cost-based formulation that decides the right amount of load that can be put on the 3G network to maximize the user’s benefit. Pralhad Deshpande, Xiaoxiao Hou, Samir R. Das In proceedings of the 10th ACM Internet Measurement Conference (IMC 2010), Melbourne, Australia, November 1-3, 2010 Short abstract: We perform a head-to-head comparison of the performance characteristics of a 3G network operated by a nation-wide provider and a metro-scale WiFi network operated by a commercial ISP, from the perspective of vehicular network access. It is conceivable that the properties that we discover can be judiciously exploited for a hybrid network design where 3G data can be offloaded to WiFi for better performance and to reduce 3G network congestion and to lower costs. Aaron Schulman, Vishnu Navda, Ramachandran Ramjee, Neil Spring, Pralhad Deshpande, Calvin Grunewald, Venkata N. Padmanabhan, Kamal Jain In proceedings of the 16th Annual International Conference on Mobile Computing and Networking (MobiCom 2010), Chicago, Illinois, USA, September 20-24, 2010 Short abstract: Cellular radios consume more power and suffer reduced data rate when the signal is weak. To realize energy savings, applications must preferentially communicate when the signal is strong, either by deferring non-urgent communication or by advancing anticipated communication to coincide with periods of strong signal. Allowing applications to perform such scheduling requires predicting signal strength, so that opportunities for energy-efficient communication can be anticipated. In this paper, we make several contributions towards a practical system for energy-aware cellular data scheduling called Bartendr. Pralhad Deshpande, Anand Kashyap, Chul Sung, Samir R. Das In the proceedings of the 7th ACM International Conference on Mobile Systems, Applications, and Services (MobiSys 2009), Krakao, Poland, June 22-25, 2009 Short abstract: With the proliferation of WiFi technology, many WiFi networks are accessible from vehicles on the road making vehicular WiFi access realistic. However, several challenges exist: long latency to establish connection to a WiFi access point (AP), lossy link performance, and frequent disconnections due to mobility. We argue that people drive on familiar routes frequently, and thus the mobility and connectivity related information along their drives can be predicted with good accuracy using historical information such as GPS tracks with timestamps, RF fingerprints, and link and network-layer addresses of visible APs. We exploit such information to develop new handoff and data transfer strategies. Anand Prabhu Subramanian, Pralhad Deshpande, Jie Gao, Samir R. Das In the proceedings of the 27th Annual IEEE Conference on Computer Communications (INFOCOM'08), Phoenix, Arizona, April 15-17, 2008. Short abstract: We use a steerable beam directional antenna mounted on a moving vehicle to localize roadside WiFi access points (APs), located outdoors or inside buildings. The idea is to estimate the angle of arrival of frames transmitted from the AP using signal strength information on different directional beams of the antenna as the beam continuously rotates while the vehicle is moving. This information together with the GPS locations of the vehicle are used in a triangulation approach to localize the APs. We show how this method must be extended using a clustering approach to account for multi-path reflections in cluttered environments. Anand Prabhu Subramanian, Vishnu Navda, Pralhad Deshpande, Samir R. Das In the proceedings of the fifth ACM International Workshop on VehiculAr Inter-NETworking (VANET 2008), San Fransisco, USA, September 15, 2008. Short abstract: We provide a measurement study of a single vehicle-to-vehicle (V2V) link using 802.11b as the link layer technology. Our goal is to investigate practical usage of steerable beam directional antennas to improve V2V communications. It is observed that directional beamforming improves the link SNR significantly, that translates to significant range improvements. However, to achieve this performance gain both antenna beams must be steered appropriately in the right direction. Tech ReportsPralhad Deshpande, Xiaoxiao Hou, Samir R. Das Short abstract: We investigate a hybrid wireless access network design that integrates 3G and WiFi networks, specifically targeting vehicular mobility. The goal is to shift the load from the expensive 3G network to the less expensive WiFi network without hurting the user experience. Instead of simply striping data over two network connections, we develop a utility and cost-based formulation that decides the right amount of load that can be put on the 3G network to maximize users benefit. We develop and experiment with a scheduler to do this. We show that the hybrid design is able to deliver much superior mobile video streaming experience for the user while reducing the load on the 3G network by three-fourth. PostersPralhad Deshpande, Xiaoxiao Hou, Samir R. Das Vishnu Navda, Anand Prabhu Subramanian, Pralhad Deshpande, Kannan Dhanasekaran, Andreas Timm-Giel, Samir R. Das Pralhad Deshpande, Shweta Jain, Samir Das, Jon Longtin Miscelleneous ProjectsPralhad Deshpande, Shweta Jain, Samir Das, Jon Longtin In the Summer of 2007, I stayed back at Stony Brook to work on this interesting project. We developed from scratch a prototype for an Automated Meter Reading System that could be retrofitted on commercial gas meters. The devices digitally store the meter readings and periodically wake up to route the gathered data in an ad-hoc manner to a base station connected to a wired backhaul network. Pralhad Deshpande This project is aimed at creating a tool that can take an arbitraty ELF library and intercept all the system calls made in it. Apart from a clear performance advantage over other sand-boxing techniques and ease of programming complex extensions, library based system call interception can be very useful because the interception code runs within the context of the monitored process. I can intercept all system calls made in libc using this tool. Pralhad Deshpande iKTG is an attempt to create a one-box Network traffic generator that will run on affordable hardware and saturate a high-end web server. iKTG is capable of generating 30.6K HTTP1.1 requests/second and achieve TCP throughput of 800 Mbps on a Gigabit Network. Running on Linux Kernel 2.6.18 and Dell Power Edge SC 1425 hardware platform iKTG can saturate 3 Server machines with the same configuration. Pralhad Deshpande B.E. Project, Goa University, India Created new traffic generators to add to the httperf trafic generation suit. This involved simulating user sessions where each simmulated user accessed web pages according to the current state of his finite state machine. The probabilities of jumping between any two pages are derieved from the server logs. Also added a probabilistic retry model where a user tries to access a page with certain probability upon a failure to retrieve it. Links: Google | DBLP | Linkedin | SBU | CS |