Qualification: 
Ph.D, M.Tech, BE
mk_panda@cb.amrita.edu

Dr. Manoj Kumar Panda currently serves as an Assistant Professor (SG) at the Department of Electronics and Communication Engineering, School of Engineering, Amrita Vishwa Vidyapeetham, Coimbatore campus.

Dr. Panda received Ph. D. in Electrical Communication Engineering from the Indian Institute of Science Bangalore and M. Tech. in Electrical Engineering from the Indian Institute of Technology, Kanpur. His research interest lies in the area of modeling, analysis and optimization of computer communication networks, vehicular networks, cloud-based robotic networks, and transportation networks. He is also interested in the multi-sensor fusion and multi-object tracking problems in the aforementioned networks,

Dr. Panda has published 17 journal articles in top-ranked IEEE transactions, Elsevier and Springer journals and 27 conference papers in the areas of Wireless Networks and Intelligent Transportation Systems. Two of his conference papers have won the ‘Best Paper’ and the ‘Best Student Paper’ awards. His RG score is 20.4 which is higher than 72.5% of all ResearchGate members. According to Google Scholar, his h-index is 11.

Dr. Panda joined the Department of Electronics and Communication Engineering, School of Engineering, Amrita Vishwa Vidyapeetham, Coimbatore, in December 2016. Prior to joining Amrita, he has held a four-year Research Fellow position at the Centre for Advanced Internet Architecture, Swinburne University of Technology, Australia, where he was involved in the VicRoads-funded project 'Integrated Network Management' and was responsible for developing the Traffic Queue Estimator. Prior to that, he has held post-doctoral positions at INRIA, Sophia Antipolis, France, for one year, and at Telecom SudParis, France, for two years. Prior to commencing his Ph.D., he worked as a Software Engineer in the Applied Research Group, Satyam Computer Services Ltd., Bangalore, for about two years where he won the 'Star Performer' award. He was selected for a three-month Fellowship at the Institute of Pure and Applied Mathematics (IPAM), University of California Los Angeles, for its Fall 2015 Program on “New Directions in Mathematical Approaches for Traffic Flow Management”.

Dr. Panda has co-supervised four Ph. D. students at Swinburne University of Technology, Australia, and has supervised and mentored several masters and bachelor’s students. He is a regular reviewer of several leading journals in the area of computer and communication networks, including IEEE/ACM Transactions on Networking, IEEE Transactions on Mobile Computing, IEEE Transactions on Vehicular Technology, IEEE Vehicular Technology Magazine, IEEE Communication Letters, IEEE Access, IET Communications, etc.

Education

  • January 2005 - March 2010: Ph. D. Wireless Networks
    Indian Institute of Science, Bangalore
  • July 2001 - March 2003: M. Tech. / ME /MS Electrical Engineering (Data & Optical Networks)
    Indian Institute of Technology Kanpur 
    Qualified GATE – 2001, AIR 210 in ECE (MTech Scholarship at IIT Kanpur)
     

Professional Appointments

Year Affiliation
December 2016 - Present Assistant Professor (Selection Grade), Amrita Vishwa Vidyapeetham
Domain: Teaching and Research 
March 2013 - November 2017 Postdoctoral Research Fellow (Level B4), Swinburne University of Technology, Australia
Domain: Research and Casual Teaching
February 2012-December 2012 R & D Engineer (Postdoctoral), Telecom SudParis, France 
Domain: Research
February 2011 - December 2011 Postdoctoral Fellow, INRIA, Sophia Antipolis, France
Domain: Research 
April 2010 - December 2010 Research Engineer (Postdoctoral), Telecom SudParis, France
Domain: Research
April 2003 - December 2004 Software Engineer (Post-MTech), Satyam Computer Services Limited Bangalore (Applied Research Group)
Domain: Research and Projects

Academic Responsibilities

Sl. No. Position Class/Batch Responsibility
1. Research Coordinator ECE Department (Jul 2017 – to date) Represent the department in research discussions for external collaborations; Maintain the research data of the department
2. Class Adviser ECE B / 2017–2021 Various
3. Chief Mentor (M. Tech. Course) Estimation and Detection Theory (2016 – 2017) Prepare periodical and end-semester question papers with answer keys, monitor the progress of teaching for all classes
4. Mentor (M. Tech. Course) Vehicular Networks and Communication (2016 – 2017) -do-
5. Mentor (M. Tech. Course) Data Communication and Networks (2017 – 2018, 2019 – 2020) -do-
6. Mentor (M. Tech. Course) Vehicular Communication (2017 – 2020) -do-
7. Mentor (M. Tech. Course) Communication Theory (2018 – 2020) -do-
8. Mentor (M. Tech. Course) Wireless Networks and Protocols (2017 – 2018) -do-
9. Mentor (M. Tech. Course) Multi-Sensor Data Fusion (2019 – 2020) -do-

Courses Handled

Post-Graduate / Ph. D. Courses Undergraduate
Estimation and Detection Theory (M. Tech., Communication Engineering and Signal Processing) Communication Theory
Wireless Networks and Protocols (M. Tech., Communication Engineering and Signal Processing) Data Communication and Networks
Vehicular Communications and Networks (M. Tech., Automotive Electronics) Wireless Communications (BTech Contact Course)
Vehicular Communications (M. Tech., Automotive Electronics)  
Multi-Sensor Data Fusion (M. Tech., Automotive Electronics)  

Specialized Courses Developed

Course Name Specialization Course Outcome
Stochastic Modelling and Queuing Theory (18CE722) MTech, Elective, Communication Engineering and Signal Processing CO1: Acquire the skill of mapping frequently occurring scenarios in telecommunication and computer networking into standard stochastic models, i.e., develop the ability to construct mathematical models from the physical description of the problems.
CO2: Be able to identify appropriate solution methods in each case and physically interpret the mathematical results
Delay Tolerant Networks MTech, Fractal Elective, Communication Engineering and Signal Processing CO1: Be able to model and analyze communication scenarios with disruption applying the delay-tolerant framework
Network Coding MTech, Fractal Elective, Communication Engineering and Signal Processing CO1: Be able to demonstrate the improvement in the performance of wireless networks due to network coding

FDP/ STTP/ Workshops/ Conferences Attended

  • Participated in a Faculty Enablement Program on the Internet of Things, organized by CIR, Amrita Vishwa Vidyapeetham, Coimbatore campus, from February 15-17, 2018.
    Outcome: Exposure to IoT applications and technologies; hands-on experience.

Academic Research

Ph. D. Guidance

  • Co-supervised four Ph. D. theses at Swinburne University of Technology, Australia.

PG Projects

Sl. No. Name of the Scholar Program Specialization Duration Status
1. Deexa Vashishtha M. Tech.  Automotive Electronics 2017-18 Completed
2. S. R. Nikhitha M. Tech.  Communication Engineering and Signal Processing 2017-18 Completed
3. Nithin N. M. Tech.  Automotive Electronics 2018-19 Completed
4. Sreenath S. M. Tech. Automotive Electronics 2018-19 Completed
5. Aiswarya A.  M. Tech. Communication Engineering and Signal Processing 2018-19 Completed
6. T. Leela Aiswarya M. Tech. Automotive Electronics 2019-20 Ongoing
7. Satya Goutham P. M. Tech. Automotive Electronics 2019-20 Ongoing
8. Nandan Kuppa M. Tech. Automotive Electronics 2019-20 Ongoing

Publications

Publication Type: Conference Proceedings

Year of Publication Title

2020

M. Nithin and Manoj Kumar Panda, “Multiple Model Filtering for Vehicle Trajectory Tracking with Adaptive Noise Covariances”, Intelligent Computing, Information and Control Systems. Springer International Publishing, Cham, pp. 557-565, 2020.[Abstract]


As the automotive world is moving towards its ultimate aim of fully autonomous vehicles, predicting the trajectories itself and that of the neighboring vehicles is essential for each vehicle. This paper proposes a novel filtering method for predicting the path of an ego vehicle (i.e., a vehicle of interest) using measurements by a Global Positioning System (GPS) device and combining such measurements with multiple candidate kinematic motion models. The proposed Multiple Model filtering method adapts to the noise conditions as inferred by measurements. It is shown that the proposed adaptive method provides a considerable level of improvement compared to the existing non-adaptive multiple model filtering.

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2020

C. V. N. S. Lalitha, Aditya, M., and Manoj Kumar Panda, “Smart Irrigation Alert System Using Multihop Wireless Local Area Networks”, Inventive Computation Technologies. Springer International Publishing, Cham, pp. 115-122, 2020.[Abstract]


From past decades, India is an agriculture-based country where the majority of the population is heavily dependent on farming. However, energy management and resource conservation continues to be the major issues in agricultural domain. The main motivations of this research is to conserve water which is a fast depleting source, and also automates the process of watering in order to reduce human workload in remote areas. In this paper, a smart irrigation alert system is developed using NodeMCU boards, a soil moisture sensor and a servo motor. The sensor measures the volumetric content of water in the soil and data is uploaded to the cloud. The main challenge addressed in this research is to seamlessly connect multiple Node MCUs to a sink (or, gateway) node such that the data can be uploaded to the cloud. Two topologies are considered. The first one is the star topology which is efficient for a kitchen garden where each of the plants is in close proximity of the sink. The second one is the multi-hop topology which is necessary in a big agriculture field. The soil moisture is sensed using multiple FC-28 sensors and uploaded to the cloud. When the moisture content drops below the threshold value, an alert notification is sent to the subscriber by e-mail and automatic watering follows by actuating the servo motor. The user can monitor and control the status of watering anywhere through the Internet. The integration of sensors, cloud and the servo motor through multiple Node MCUs is the main novelty of this work.

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2019

S. Sreenath and Manoj Kumar Panda, “Traffic Counting and Turning Fraction Estimation using Vehicle-to-UAV Co-operative communication”, 2019 3rd International Conference on Trends in Electronics and Informatics (ICOEI). 2019.[Abstract]


The current roads and supporting infrastructure are often found to be incapable of handling the rapid increase in traffic, leading to congestion and incidents. The availability of accurate and real-time information about the traffic demands may go a long way in designing better traffic control and management systems. Two important quantities of interest for traffic control are the ‘traffic count’ on road segments between junctions and ‘turning fractions’ at the junctions. Together, these two quantities can determine the traffic flow requirements over the road network. The aims of the paper are to investigate the performance of the Vehicle-to-UAV (V2U) communication method for traffic counting and turning fraction estimation using vehicular network simulations and compare with the performance of Bluetooth and loop detectors.

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2019

S. Smruthi, Krishna, R. S., and Manoj Kumar Panda, “Low Energy Sensor Data Collection using Unmanned Aerial Vehicles”, 2019 3rd International Conference on Trends in Electronics and Informatics (ICOEI). 2019.[Abstract]


Wireless Sensor Networks (WSNs) are one of the most important technologies today due to their numerous applications in the fields of environment monitoring, defense and agriculture, to name a few. The paper proposes some architectural alternatives to the traditional WSNs with static sinks by including mobile sinks mounted on Unmanned Aerial Vehicles (UAVs). The main performance measures of interest, energy consumption per node, throughput evolution over time, and delay per packet are studied and compared for the different architectures. The simulation results exhibit how better performance is achieved by using a mobile sink than with a static sink and how clustered topologies perform better than flat topologies.

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2018

S. R. Nikhitha and Manoj Kumar Panda, “Optimal sensor data harvesting using a mobile sink”, Procedia Computer Science, vol. 143. Elsevier B.V., pp. 921-930, 2018.[Abstract]


We investigate the idea of using a fixed-wing Unmanned Aerial Vehicle (UAV) as a mobile sink in a Wireless Sensor Network (WSN) to increase the network lifetime. We formulate and solve an optimization problem to minimize the scanning delay incurred by the UAV subject to a motion energy constraint. We also formulate and solve another optimization problem to minimize the total energy consumption for motion of the UAV and communication between the UAV and the sensor nodes subject to a delay constraint. These two optimization problems are for the case when the UAV collects the sensor data by communicating with certain special nodes called Cluster Heads. For the alternative architecture, where the UAV directly communicates with each sensor node, we investigate the performance using NS-2 simulations and provide several insightful observations. © 2018 The Authors. Published by Elsevier B.V.

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2017

Tarikul Islam, Hai Le Vu, Manoj Kumar Panda, Hoang, N., and Dong Ngoduy, “The Accuracy of Cell-based Dynamic Traffic Assignment: Impact of Signal Control on System Optimality”, The 20th International Conference of Hong Kong Society for Transportation Studies, Dec2015, Hong Kong. pp. 355-362, 2017.[Abstract]


Dynamic Traffic Assignment (DTA) provides an approach to determine the optimal path and/or departure time based on the transportation network characteristics and user behavior (e.g., selfish or social). In the literature, most of the contributions study DTA problems without including traffic signal control in the framework. The few contributions that report signal control models are either mixed-integer or nonlinear formulations and computationally intractable. The only continuous linear signal control method presented in the literature is the Cycle-length Same as Discrete Time-interval (CSDT) control scheme. This model entails a trade-off between cycle-length and cell-length. Furthermore, this approach compromises accuracy and usability of the solutions.
In this study, we propose a novel signal control model namely, Signal Control with Realistic Cycle length (SCRC) which overcomes the trade-off between cycle-length and cell-length and strikes a balance between complexity and accuracy. The underlying idea of this model is to use a different time scale for the cycle-length. This time scale can be set to any multiple of the time slot of the Dynamic Network Loading (DNL) model (e.g. CTM, TTM, and LTM) and enables us to set realistic lengths for the signal control cycles. Results show, the SCRC model not only attains accuracy comparable to the CSDT model but also more resilient against extreme traffic conditions. Furthermore, the presented approach substantially reduces computational complexity and can attain solution faster.

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2017

A. Rahman, Jin, J., Cricenti, A., Rahman, A., and Manoj Kumar Panda, “Motion and Connectivity Aware Offloading in Cloud Robotics via Genetic Algorithm”, GLOBECOM 2017 - 2017 IEEE Global Communications Conference. 2017.[Abstract]


Task offloading opens a gateway for robotic applications to leverage computation support from the cloud infrastructure. It exploits a trade-off between the robot's and cloud's processing capabilities, and the communication between the two entities plays a critical role in making these decisions. Two major factors that significantly influence communication are network connectivity (bandwidth) and mobility of the robot. We integrate these two factors with the offloading decisions to formulate an optimization problem. Our objective in this paper is to improve the quality of service (QoS) for a 25 node application taskflow, known as direct acyclic graph. We propose a genetic algorithm based approach to solve the optimization problem which performs a novel three-layer decision making: (i) whether to offload a task or not, (ii) path planning to reach a desired location for offloading/local execution, (iii) select access point to associate with for offloading. We simulate for a smart city scenario consisting of 36-cell workspace with obstacles and compare the offloading results with a well- established fixed movement offloading method. The outcomes of our study suggest that motion and connectivity aware offloading leads to more efficient performance in terms of improved QoS and minimum consumption of resources, i.e., energy, time or distance.

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2016

M. Haghighatt, Manoj Kumar Panda, Hai Le Vu, and van Lint, H., “Large-scale congestion analysis using compressed measurements”, 2016 IEEE 19th International Conference on Intelligent Transportation Systems (ITSC). 2016.[Abstract]


Traffic congestion is a major concern in metropolitan areas and a quick congestion assessment of large-scale network is required for modern traffic management referred to as Intelligent Transport Systems (ITS). However, ITSs are facing the challenge of real-time storage, retrieval and processing of a vast amount of collected data over a large-scale network. Compressed sensing (CS) is an efficient technique of sampling high-dimensional data and is successfully used to reconstruct signals via a small set of non-adaptive, linear measurements. Whilst CS has mainly been applied for data reconstruction, we propose in this paper the use of CS for classification and estimation of some meaningful parameters in the traffic problem. To this end, we develop a novel sensing matrix for congestion analysis and show that for traffic data collected in Melbourne urban network, our CS provides an opportunity to extract the desired information from a small number of random projections. In addition, our method could improve the efficiency of database query and has the ability to deal with missing or defective data.

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2015

B. Dhivyabharathi, Fulari, S., Amrutsamanvar, R., Vanajakshi, L., Subramanian, S. C., and Manoj Kumar Panda, “Performance Comparison of Filtering Techniques for Real Time Traffic Density Estimation under Indian Urban Traffic Scenario”, 2015 IEEE 18th International Conference on Intelligent Transportation Systems. 2015.[Abstract]


Real time traffic state estimation is important to facilitate better traffic management in urban areas and is a prime concern from a traffic engineer's viewpoint. Traffic density is a key traffic variable that can be used to characterize the traffic system and can be a valuable input to the functional areas of Intelligent Transportation Systems (ITS). However, measurement of density in the field is difficult due to several practical limitations. This creates a need for inferring density from other traffic variables that are easily measurable in the field. In this paper, model based approaches for the estimation of traffic density are discussed. The non-linear model equations are based on the conservation principle and the fundamental traffic flow. The technique used for recursive estimation of density in real time plays a key role in terms of estimation accuracy. The Extended Kalman Filter (EKF) is a common tool for recursive estimation for nonlinear systems. This study investigates the application of particle filter (PF) and Unscented Kalman Filter (UKF) as alternatives to (EKF) for non-linear traffic state estimation in the context of traffic conditions in India. The estimated density values were corroborated using manually extracted field density values. The performance of these methods was also compared with a base model, where the fundamental traffic flow equation was used for calculating density. The convergence properties of these filters were also analyzed.

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2014

Manoj Kumar Panda, Hoang, T., and Hai Le Vu, “Improving broadcast efficiency of irresponsible forwarding with random linear coding at source”, Proceeding of IEEE International Symposium on a World of Wireless, Mobile and Multimedia Networks 2014. 2014.[Abstract]


Broadcasting is the most prevalent method for disseminating information in vehicular networks. At high vehicle densities, the so-called broadcast storm problem degrades the efficiency of broadcasting. A so-called Irresponsible Forwarding (IF) scheme has recently been proposed in the literature that can effectively combat the broadcast storm problem. For messages consisting of multiple packets, the coupon collector problem also degrades the broadcast efficiency at all vehicle densities. In this paper, we extend the basic IF scheme to multi-packet messages, which we call the max-min IF, and combine it with Random Linear Coding (RLC) of packets at the source to solve the coupon collector problem and improve the broadcast efficiency of IF. Through discrete event simulations, with a widely accepted realistic vehicular mobility model based on cellular automata, we demonstrate that our IF+RLC scheme can significantly improve the reachability in sparsely connected vehicular networks at low vehicle densities as well as reduce the mean delay under high probability of collisions at high vehicle densities.

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2012

Manoj Kumar Panda, Chahed, T., and Altman, E., “Wireless multicast cost sharing game with a dynamic population”, 2012 6th International Conference on Network Games, Control and Optimization (NetGCooP). 2012.[Abstract]


In this paper, we study a wireless multicast cost sharing game where the population of users is dynamically changing due to random arrivals and departures. Each user can either subscribe to a dedicated (wired or wireless) connection of fixed cost or join a multicast session served by a wireless Base Station (BS). In the latter case, the instantaneous cost of transmission at any time is shared among the users that are present in the multicast session at that time. Each user, being selfish, chooses one of the two options so as to minimize its own share of cost. We characterize the symmetric equilibria with several information availability structures. With only distributional information, we obtain the probability with which a random user would join the multicast session under the Highest Cost Allocation (HCA), the Incremental Cost Allocation (ICA) and the Shapley Value Allocation (SVA) schemes. We observe that, if the the number of users in the session is made available to the users, then the equilibrium strategy of the users is to join the multicast session when at least one other user is already present and to randomize only when there is none.

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2012

A. Ali, Altman, E., Chahed, T., Fiems, D., Manoj Kumar Panda, and Sassatelli, L., “Estimating File-Spread in Delay Tolerant Networks under Two-Hop Routing”, NETWORKING 2012. Springer Berlin Heidelberg, Berlin, Heidelberg, 2012.[Abstract]


We consider a Delay/Disruption Tolerant Network under two-hop routing. Our objective is to estimate and track the degree of spread of a message/file in the network. Indeed, having such real-time information is critical for on-line control of routing and energy expenditure. It also benefits the multi-casting application. With exponential inter-meeting times of mobile nodes: (i) for the estimation problem, we obtain exact expressions for the minimum mean-squared error (MMSE) estimator, and (ii) for the tracking problem, we first derive the diffusion approximations for the system dynamics and the measurements and then apply Kalman filtering. We also apply the solutions of the estimation and filtering problems to predict the time when a certain pre-defined fraction of nodes have received a copy of the message/file. Our analytical results are corroborated with extensive simulation results.

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2011

A. Ali, Chahed, T., Altman, E., Manoj Kumar Panda, and Sassatelli, L., “A new proposal for reliable unicast and multicast transport in Delay Tolerant Networks”, 2011 IEEE 22nd International Symposium on Personal, Indoor and Mobile Radio Communications. 2011.[Abstract]


We propose a new scheme for reliable transport, both for unicast and multicast flows, in Delay Tolerant Networks (DTNs). Reliability is ensured through the use of Global Selective ACKnowledgements (G-SACKs) which contain detailed (and potentially global) information about the receipt of packets at all the destinations. The motivation for using G-SACKs comes from the observation that one should take the maximum advantage of the contact opportunities which occur quite infrequently in DTNs. We also propose sharing of “packet header space” with G-SACK information and allow for random linear coding at the relay nodes. Our results from extensive simulations of the proposed scheme quantify the gains due to each new feature.

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2011

A. Ali, Altman, E., Chahed, T., Manoj Kumar Panda, and Sassatelli, L., “A new reliable transport scheme in Delay Tolerant Networks based on acknowledgments and random linear coding”, 2011 23rd International Teletraffic Congress (ITC). 2011.[Abstract]


We propose a new reliable transport scheme for Delay Tolerant Networks (DTNs) based on the use of acknowledgments (ACKs) as well as coding. We, specifically, develop a fluid-limit model to derive expressions for the delay performance of the proposed reliable transport scheme and derive the optimal setting of the parameters which minimize the file transfer time. Our results yield optimal values for the number of outstanding random linear combinations to be sent before time-out as well as the optimal value of the time-out itself, which, in turn, minimize the file transfer time.

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2010

P. Agrawal, Kumar, A., Kuri, J., Manoj Kumar Panda, Navda, V., Ramjee, R., and Padmanabhani, V. N., “Analytical models for energy consumption in infrastructure WLAN STAs carrying TCP traffic”, 2010 Second International Conference on COMmunication Systems and NETworks (COMSNETS 2010). 2010.[Abstract]


We develop analytical models for estimating the energy spent by stations (STAs) in infrastructure WLANs when performing TCP controlled file downloads. We focus on the energy spent in radio communication when the STAs are in the Continuously Active Mode (CAM), or in the static Power Save Mode (PSM). Our approach is to develop accurate models for obtaining the fraction of times the STA radios spend in idling, receiving and transmitting. We discuss two traffic models for each mode of operation: (i) each STA performs one large file download, and (ii) the STAs perform short file transfers. We evaluate the rate of STA energy expenditure with long file downloads, and show that static PSM is worse than just using CAM. For short file downloads we compute the number of file downloads that can be completed with given battery capacity, and show that PSM performs better than CAM for this case. We provide a validation of our analytical models using the NS-2 simulator.

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2010

P. Agrawal, Kumar, A., Kuri, J., Manoj Kumar Panda, Navda, V., and Ramjee, R., “OPSM - Opportunistic Power Save Mode for Infrastructure IEEE 802.11 WLAN”, 2010 IEEE International Conference on Communications Workshops. 2010.[Abstract]


We focus on the energy spent in radio communication by the stations (STAs) in an IEEE 802.11 infrastructure WLAN. All the STAs are engaged in web browsing, which is characterized by a short file downloads over TCP, with short duration of inactivity or think time in between two file downloads. Under this traffic, Static PSM (SPSM) performs better than CAM, since the STAs in SPSM can switch to low power state (sleep) during think times while in CAM they have to be in the active state all the time. In spite of this gain, performance of SPSM degrades due to congestion, as the number of STAs associated with the access point (AP) increases. To address this problem, we propose an algorithm, which we call opportunistic PSM (OPSM). We show through simulations that OPSM performs better than SPSM under the aforementioned TCP traffic. The performance gain achieved by OPSM over SPSM increases as the mean file size requested by the STAs or the number of STAs associated with the AP increases. We implemented OPSM in NS-2.33, and to compare the performance of OPSM and SPSM, we evaluate the number of file downloads that can be completed with a given battery capacity and the average time taken to download a file.

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2009

Manoj Kumar Panda and Kumar, A., “Modeling multi-cell IEEE 802.11 WLANs with application to channel assignment”, 2009 7th International Symposium on Modeling and Optimization in Mobile, Ad Hoc, and Wireless Networks. 2009.[Abstract]


We provide a simple and accurate analytical model for multi-cell IEEE 802.11 WLANs. Our model applies if the cell radius, R, is much smaller than the carrier sensing range, Rcs. We argue that, the condition Rcs >> R is likely to hold in a dense deployment of access points (APs). We develop a scalable cell level model for such WLANs with saturated nodes as well as for TCP-controlled long file downloads. The accuracy of our model is demonstrated by comparison with ns-2 simulations. Based on the insights provided by our analytical model, we propose a simple channel assignment algorithm which provides static assignments that are Nash equilibria in pure strategies for the objective of maximizing normalized network throughput, and requires only as many steps as there are channels. Furthermore, our channel assignment algorithm does not require any a priori knowledge of topology and can be implemented in a decentralized manner. In contrast to prior work, our approach to channel assignment is based on the throughput metric.

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2009

O. Bhardwaj, Sharma, G. V. V., Manoj Kumar Panda, and Kumar, A., “Modeling finite buffer effects on TCP traffic over an IEEE 802.11 infrastructure WLAN”, 2009 First International Communication Systems and Networks and Workshops. 2009.[Abstract]


The network scenario is that of an infrastructure IEEE 802.11 WLAN with a single AP with which several stations (STAs) are associated. The AP has a finite size buffer for storing packets. In this scenario, we consider TCP controlled upload and download file transfers between the STAs and a server on the wireline LAN (e.g., 100 Mbps Ethernet) to which the AP is connected. In such a situation, it is known (see, for example, [3], [9]) that because of packet loss due to finite buffers at the AP, upload file transfers obtain larger throughputs than download transfers. We provide an analytical model for estimating the upload and download throughputs as a function of the buffer size at the AP. We provide models for the undelayed and delayed ACK cases for a TCP that performs loss recovery only by timeout, and also for TCP Reno.

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2009

Manoj Kumar Panda and Kumar, A., “State dependent attempt rate modeling of single cell IEEE 802.11 WLANs with homogeneous nodes and poisson arrivals”, 2009 First International Communication Systems and Networks and Workshops. 2009.[Abstract]


Analytical models of IEEE 802.11-based WLANs are invariably based on approximations, such as the well-known mean-field approximations proposed by Bianchi for saturated nodes. In this paper, we provide a new approach for modeling the situation when the nodes are not saturated. We study a State Dependent Attempt Rate (SDAR) approximation to model M queues (one queue per node) served by the CSMA/CA protocol as standardized in the IEEE 802.11 DCF. The approximation is that, when n of the M queues are non-empty, the attempt probability of the n non-empty nodes is given by the long-term attempt probability of n saturated nodes as provided by Bianchi's model. This yields a coupled queue system. When packets arrive to the M queues according to independent Poisson processes, we provide an exact model for the coupled queue system with SDAR service. The main contribution of this paper is to provide an analysis of the coupled queue process by studying a lower dimensional process and by introducing a certain conditional independence approximation. We show that the numerical results obtained from our finite buffer analysis are in excellent agreement with the corresponding results obtained from ns-2 simulations. We replace the CSMA/CA protocol as implemented in the ns-2 simulator with the SDAR service model to show that the SDAR approximation provides an accurate model for the CSMA/CA protocol. We also report the simulation speed-ups thus obtained by our model-based simulation.

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2005

A. Kumar, Altman, E., Goyal, M., Kumar, V., Miorandi, D., Manoj Kumar Panda, Ramaiyan, V., and Srinivasan, S. H., “Analysis and optimisation of IEEE 802.11 wireless local area networks”, Proceedings - WiOpt 2005: Third International Symposium on Modeling and Optimization in Mobile, Ad Hoc, and Wireless Networks. Trentino, 2005.[Abstract]


In the recent years, IEEE 802.11 wireless local area networks (WLANS) have increasingly been deployed in a variety of situations, such as homes, business enterprises, academic campuses, and public places such as airports, hotels, and shopping centers. It has therefore become very important to understand the performance of such networks, and also how to effectively design, deploy and manage them. In this paper our concern is mainly with the analytical performance evaluation of WLANs. We will also consider an aspect of optimisation of such networks. We will begin with a discussion of saturation throughput analysis of single cell WLANs. In this context the seminal contribution is due to G. Bianchi who proposed a decoupling approximation that led to a fixed point equation, the solution of which yielded an approximation to the attempt rate of any node. We show that, in fact, the fixed point equation can be established using a renewal reward argument and in a much more general setting. Further, in this setting a natural condition on the back-off sequence leads to uniqueness of the fixed point. It is possible to take the same decoupling approximation and develop a vector fixed point equation, assuming that the nodes have possibly unequal attempt rates. If a vector fixed point has unequal coordinates, then we say that it is unbalanced. The traditional approach only considered balanced fixed points. We consider the vector fixed point equation, and show that, in general, there can exist multiple unbalanced fixed points, even in those situations where there is a unique balanced fixed point. Simulations show that in situations where this happens the system exhibits significant short term unfairness, and further, the balanced fixed point analysis fails to capture the steady state performance. For the case in which the mean back-off grows multiplicatively with collisions, we establish a sufficient condition for a system to have a unique fixed point (that is also balanced). The original IEEE 802.11 medium access control (MAC) mechanism provided no means for differentiating the channel access provided to the contending devices. A new addition to the IEEE 802.11 suite of standards, IEEE 802.11e, now provides several access differentiation mechanisms. One set of mechanisms differentiates access by permitting different devices (or queues in devices) to have different channel access parameters, such as the initial back-off, the back-off multiplier, and the maximum back-off. Another, mechanism is that, after every successful transmission, nodes with a lower access priority wait for a little longer than other nodes before reinitiating their back-off and attempt processes, thus giving the higher priority class nodes a better chance to access the channel. This latter mechanism is called AIFS (arbitration interframe space). The vector fixed point analysis is extended to both these mechanisms, and we establish a condition for uniqueness of the fixed point. For all the above access mechanisms, we also provide asymptotic results in the regime where the number of retrials is unbounded and the number of nodes goes to ∞. This analysis provides interesting analytical insights into the role of some of the access parameters. Saturation throughput analysis is normally conducted to assess the "capacity" of these networks. However, it is possible to use the saturation throughput analysis directly in certain application situations. We provide a demonstration of this in the context of TCP controlled transfer of large files. While much of the analysis discussed above is for single cell WLANs, in practice, in order to cover large spaces, WLANs comprise multiple overlapping cells. Since there are only three nonoverlapping frequency bands in the operational spectrum, in a typical WLAN deployment, cochannel WLAN cells will overlap. We develop a fixed point based saturation throughput analysis of two cells whose decoding ranges are disjoint but their carrier sense ranges completely overlap. The analysis captures an interesting unfairness that occurs in this situation. The model turns out to be similar to the one obtained for the AIFS based throughput differentiation mechanism mentioned above. At the present time there do not appear to be systematic techniques to design and optimise WLANs. We will briefly discuss the problem of optimal association of devices to access points (APs) in an infrastructure WLAN. The problem is that there are several mobile devices, each of which can potentially connect via one of several candidate APs, at various physical layer rates. The question is: "What is an optimal association?" We formulate the problem as one of maximising, over the possible associations, the sum of the up-link utilities obtained at the devices. Thus the problem is like the optimal bandwidth sharing problem, well known in wired packet networks, with the additional complexity that the network "topology" also needs to be simultaneously obtained. We formulate the problem, discuss the issues, and provide some preliminary results.

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2005

Manoj Kumar Panda and Srinivasan, S. H., “Simplified Queue Dynamics with Mixed Traffic for Congestion Control at Routers”, EuroIMSA. 2005.

2005

Manoj Kumar Panda, Kumar, A., and Srinivasan, S. H., “Saturation throughput analysis of a system of interfering IEEE 802.11 WLANs”, Sixth IEEE International Symposium on a World of Wireless Mobile and Multimedia Networks. 2005.[Abstract]


IEEE 802.11 wireless local area networks that span large buildings or campuses must comprise multiple cells, several of which must necessarily be cochannel cells. It can be shown that in such multicell networks, typically, the radio ranges of cochannel cells overlap. The paper studies the saturation throughput performance of two cochannel cells with critical overlap, i.e., their interference ranges completely overlap but no node in either cell can decode any transmissions from the other cell. We identify that the difference between the two MAC parameters, EIFS (extended interframe space) and DIFS (DCF interframe space) is a key issue and incorporate this difference as a parameter into an analytical model. The model yields a fixed point equation that yields an approximation to the saturation throughputs of the two cells. The results from the analysis are validated against ns-2 simulations. We find that with EIFS>DIFS there is substantial temporal unfairness in the channel access between the two cells, but, because of fewer collisions, the critical overlap configuration has higher per cell throughput than if the cells' decoding ranges overlapped.

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2004

Manoj Kumar Panda, Venkatesh, T., Sridhar, V., and Singh, Y. N., “Architecture for a class of scalable optical cross-connects”, First International Conference on Broadband Networks. 2004.[Abstract]


A new class of optical cross-connects (OXCs) is being proposed. These OXCs are highly scalable and possess the flexibility of 3-stage Clos networks so that various non-blocking properties, viz., rearrangeably nonblocking and strictly nonblocking (SNB) can be obtained from the same architecture. They are well-suited to implement SNB OXCs with high values of wavelength to fiber ratio, require lesser number of blocks than Clos network and support both fiber and wavelength scalability. The OXCs when implemented in three-dimensional micro-opto-electro-mechanical systems (3D MOEMS) technology provide greater advantages. A specific instance of the class of architectures is suitable for limited-range wavelength converters.

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2004

Manoj Kumar Panda and Srinivasan, S. H., “Loss sharing with TTL routing”, 2004 IEEE International Conference on Multimedia and Expo (ICME) (IEEE Cat. No.04TH8763). 2004.[Abstract]


The boom in new streaming media applications in the recent past calls for innovative strategies that can support both data and media over the same global IP based Internet in a fair and efficient manner. Several solutions have already been proposed to control the rate of media traffic and to maintain fairness among the heterogeneous traffic flows. We propose a mechanism that solves many of the problems associated with the earlier schemes. A new concept, called "loss sharing", is introduced for 'media rate control' and 'maintenance of fairness'. We show that these two objectives are automatically achieved as desirable side-effects of the recently proposed "TTL routing algorithm". This algorithm adopts a new interpretation of the TTL (time-to-live) field of the IP header. It is shown that rate control by "TTL routing" has certain other desirable features.

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Publication Type: Journal Article

Year of Publication Title

2019

S. R. Pokhrel, Manoj Kumar Panda, and Hai Le Vu, “Fair Coexistence of Regular and Multipath TCP over Wireless Last-Miles”, IEEE Transactions on Mobile Computing, vol. 18, no. 3, pp. 574-587, 2019.[Abstract]


Recent advancements in Internet congestion control have introduced a multipath TCP (MPTCP) that aims to simultaneously utilize multiple available paths in the network. In this paper, we develop an integrated fluid and packet-level analytical model to study the coexistence of regular and MPTCP users sharing a common WiFi access point (AP). We observe a throughput unfairness of MPTCP with regular TCP in the last-mile WiFi networks. In order to fix the fairness issue, we develop a real-time Adaptive Loss Management (ALM) algorithm that continuously monitors the deviation in AP buffer occupancy and adapts its packet admission probability based on a closed form expression derived from our analytical model. We provide a proof as well as show via numerical and simulation results that the proposed ALM algorithm is TCP-friendly by design, and provably stable.

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2019

Tarikul Islam, Hai Le Vu, and Manoj Kumar Panda, “System optimal dynamic traffic assignment: solution structures of the signal control in non-holding-back formulations”, Transportmetrica B: Transport Dynamics, vol. 7, no. 1, pp. 967-991, 2019.[Abstract]


This paper devises locally optimal traffic Signal Control (SC) settings in a Non-Holding-Back Dynamic Traffic Assignment with SC (NHB DTA-SC) formulation for single destination (i.e. one source to one destination and many sources to one destination) networks. To this end, we apply temporal–spatial dual decomposition method and decompose the NHB DTA-SC problem into intersection cells and non-intersection cells. Then we further decompose the intersection cells into different subproblems, i.e. Occupancy Minimization (OM), Flow Maximization (FM), and SC. To study the optimal SC structures, we examine the Karush–Kuhn–Tucker (KKT) optimality conditions of the decomposed SC subproblem. Finally, we obtain the locally optimal SC structures under different network conditions that include over-saturated, under-saturated, and queue spillback traffic scenarios. We also present several numerical results to verify the optimality structures found by our theoretical derivations.

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2019

N. H. Hoang, Hai Le Vu, Manoj Kumar Panda, and Lo, H. K., “A linear framework for dynamic user equilibrium traffic assignment in a single origin-destination capacitated network”, Transportation Research Part B: Methodological, vol. 126, pp. 329 - 352, 2019.[Abstract]


The dynamic traffic assignment (DTA) problem has been studied intensively in the literature. However, there is no existing linear framework to solve the user equilibrium (UE) DTA problem. In this paper, we develop a novel linear programming framework to solve the UE-DTA problem in a dynamic capacity network that exploits the linkage between the UE and system optimal (SO) solutions underpinned by a first-in-first-out (FIFO) principle. This important property enables us to develop an incremental loading method to obtain the UE solutions efficiently by solving a sequence of linear programs. The proposed solution methodology possesses several nice properties such as a predictable number of iterations before reaching the UE solution, and a linear system of equations to be solved in each of the iterations. In contrast to the related iterative methods, such as Frank–Wolfe algorithm, successive average (MSA) or projection and their extensions where the purpose of iteration is to seek the solution convergence, whereas ours is to solve a linear problem over multiple iterations but only for a single unit of demand in each iteration. Furthermore, we provide a theoretical proof that in the limit, the SO objective can be used to obtain the UE solution as the system time step goes to zero given the satisfaction of the FIFO constraint. We show via numerical examples the significant improvements in the obtained UE solutions both in terms of accuracy and computational complexity.

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2019

Manoj Kumar Panda, Dong Ngoduy, and Hai Le Vu, “Multiple model stochastic filtering for traffic density estimation on urban arterials”, Transportation Research Part B: Methodological, vol. 126, pp. 280-306, 2019.[Abstract]


Traffic state estimation plays an important role in Intelligent Transportation Systems (ITS). It provides the latest traffic information to travelers and feedback to signal control systems. The Interactive Multiple Model (IMM) filtering provides a powerful estimation method to deal with the non-differentiable nonlinearity caused by the phase transitions between the under-critical and above-critical traffic density regimes. The IMM filtering also accounts for the uncertainty in the current ‘mode of operation’. In this paper, we develop an enhanced IMM filtering approach to traffic state estimation, with an underlying Cell Transmission Model (CTM) for traffic flow propagation. We improve the IMM filtering with CTM in two ways: (1) We apply two simplifying assumptions that are highly likely to hold in urban roads in incident-free conditions, which makes the computational complexity to grow with the number of cells only polynomially, rather than exponentially as reported in prior work. (2) We apply a novel approach to noise modeling wherein the process noise is explicitly obtained in terms of the randomness in more fundamental quantities (e.g., free-flow speed, maximum flow capacity, etc.), which not only makes noise calibration using real data convenient but also makes the computation of the cross-correlation between the process and measurement noises transparent. However, it leads to ‘process dynamic’ and ‘measurement’ equations that involve multiplier matrices whose elements are random variables rather than deterministic scalars, and hence, standard filtering equations cannot be applied. We derive the appropriate filtering equations from first principles. We calibrate the traffic parameters and the total inflow and outflow on the links using the SCATS loop detector data collected in Melbourne and report significant improvements in accuracy, which is due to the accurate computation of the cross-covariance of process and measurement noises. © 2019 Elsevier Ltd More »»

2018

H. P. Luong, Manoj Kumar Panda, Hai Le Vu, and Vo, B. Q., “Beacon Rate Optimization for Vehicular Safety Applications in Highway Scenarios”, IEEE Transactions on Vehicular Technology, vol. 67, no. 1, pp. 524-536, 2018.[Abstract]


Vehicle-to-vehicle (V2V) communication enables exchanging information between vehicles by broadcasting safety and beacon messages. Safety applications based on a so-called dedicated short-range communication, which are one of the main applications of V2V, require a very strict network performance for safety messages. In this paper, we investigate the effect of the beacon rate on the network performance of safety messages and develop an optimization problem to recommend optimal beacon rates based on a utility maximization framework. The message utility is constructed to account for the reliability requirements of safety messages and maintain the accuracy of neighborhood information collected by beacons. Specifically, we obtain the relationship between the optimal beacon rate and the system parameters. Our results show that the optimal beacon rates can meet the requirements of safety applications and improve the network performance up to 40%.

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2018

Tarikul Islam, Hai Le Vu, Manoj Kumar Panda, and Dong Ngoduy, “A study of realistic dynamic traffic assignment with signal control, time-scale, and emission”, Journal of Intelligent Transportation Systems, vol. 22, no. 5, pp. 446-461, 2018.[Abstract]


Dynamic Traffic Assignment (DTA) is a mathematical framework that with a System Optimal (SO) objective is often used for long-term transport planning, design, and traffic management. However, the conventional SO-DTA formulation gives optimal solutions having an unrealistic vehicle Holding–Back (HB) property. Existing approaches in the literature aiming to resolve the HB problem are either computationally intractable or suffer from recursive parameter selection problem. In addition, most of the existing Signal Control (SC) models considered in the DTA formulation are mixed-integer or nonlinear in nature that are not scalable for large networks. With an exception, there exists a linear signal control model that can only set signal control cycle-length equal to DTA time-slot duration, and thus trades the accuracy of the SO-DTA solution for a more realistic cycle-length. In this article, we address the above issues by proposing a linear Non-Holding-Back SO-DTA with SC (NHB DTA-SC) formulation for single destination networks. The embedded signal control in the proposed framework enables us to set realistic cycle-length using any DTA time-slot (i.e., flexible time-scale). We find that the time-scale has a significant impact on traffic density which affects vehicle-discharged emissions. To this end, we develop a novel linear Emission-Based DTA with SC (EB DTA-SC) formulation that obtains NHB flows as well as lowest possible emission. Our results show that there is a 32% difference between emission estimated by 60-second and 5-second time-scales.

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2017

H. Phuong Luong, Manoj Kumar Panda, Hai Le Vu, and Vo, Q. Bao, “Analysis of Multi-Hop Probabilistic Forwarding for Vehicular Safety Applications on Highways”, IEEE Transactions on Mobile Computing, vol. 16, pp. 918-933, 2017.[Abstract]


Safety applications based on the dedicated short-range communication (DSRC) in vehicular networks have very strict performance requirements for safety messages (in terms of delay and packet delivery). However, there is a lack of systematic approach to achieve the performance requirements by leveraging the potential of multi-hop forwarding. This paper proposes a generic multi-hop probabilistic forwarding scheme that achieves these requirements for event-driven safety messages, is compatible with the 802.11 broadcasting protocol and inherits some of the best features of solutions proposed so far for vehicular safety applications. In addition, we develop a unified and comprehensive analytical model to evaluate the performance of the proposed scheme taking into account the effect of hidden terminals, vehicle densities, and the spatial distribution of the multiple forwarders, in a one-dimensional highway scenario. Our numerical experiments confirm the accuracy of the model and demonstrate that the proposed protocol can improve the packet delivery performance by up to 209 percent, while maintaining the delay well below the required threshold. Finally, the utility of the analytical model is demonstrated via an optimal design for the coefficients of a forwarding probability function in the proposed scheme.

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2017

B. Dhivyabharathi, Kumar, B. N. Anil, Vanajakshi, L., and Manoj Kumar Panda, “Particle Filter for Reliable Bus Travel Time Prediction Under Indian Traffic Conditions”, Transportation in Developing Economies, vol. 3, no. 13, pp. 1-11, 2017.[Abstract]


In recent times, traffic congestion has been increasing rapidly and deteriorating the quality of traffic systems in urban areas of many developed and developing countries. This became a serious problem faced by society, as many people are using private vehicles while commuting from one place to the other. One of the reasons people are shifting towards private transportation is due to lack of reliability of the public transportation systems. Attracting more travelers towards public transportation using Intelligent Transportation Systems (ITS) technologies is one way to reduce the negative impacts. In this context, prediction of bus travel time and providing information about bus arrival time to passengers accurately is a potential solution, which will help in reducing the uncertainty and waiting time associated uncertainties with public transit systems. However, for this solution to be effective, the information provided to passengers should be highly reliable. The present study proposes a model based prediction method that uses particle filtering technique for accurate prediction of bus travel times for the development of a real time passenger information system under heterogeneous traffic conditions that exist in India. The results obtained from the implementation of the above method are validated using the measured travel time. The prediction accuracy is quantified using the Mean Absolute Percentage Error (MAPE) and the performance is compared with a base approach namely, the historic average method. The quantified error in terms of MAPE is 20% for the proposed method and 37% for the historic average method, indicating the superiority of the proposed method over historic average method. Thus, it can be concluded that particle filter is a viable tool in the prediction of bus travel times.

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2017

S. R. Pokhrel, Manoj Kumar Panda, and Hai Le Vu, “Analytical Modeling of Multipath TCP Over Last-Mile Wireless”, IEEE/ACM Transactions on Networking, vol. 25, no. 3, pp. 1876-1891, 2017.[Abstract]


We develop a comprehensive analytical model for multiple long-lived multipath Transmission Control Protocol (TCP) connections downloading content from a remote server in the Internet using parallel paths with Wi-Fi and cellular last-miles. This is the first analytical model developed in the literature that captures the coupling between the paths through heterogeneous wireless networks where the coupling arises due to the multipath TCP coupled congestion control protocol. The model also takes into account the impact of the shared nature of the wireless medium and the finite access point (AP) buffer in the Wi-Fi last-mile. The accuracy of the proposed model is demonstrated via extensive ns-2 simulations. Furthermore, we discover a new type of throughput unfairness among the competing regular and multipath TCP connections going through the same AP with a droptail buffer; the regular TCP connections essentially steal almost all the Wi-Fi bandwidth away from the multipath TCP connections. To tackle this problem, we present two simple solutions utilizing our analytical model and achieve fairness.

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2016

S. Raj Pokhrel, Manoj Kumar Panda, Hai Le Vu, and Mandjes, M., “TCP Performance over Wi-Fi: Joint Impact of Buffer and Channel Losses”, IEEE Transactions on Mobile Computing, vol. 15, pp. 1279-1291, 2016.[Abstract]


We propose an analytical model for a Wi-Fi network acting as a last-mile Internet access with multiple long-lived TCP connections on both the up and down links. Our model considers the joint impact of buffer losses at the access point, contention at the medium access control layer, and packet losses due to the wireless channel being erroneous. We show that the model accurately quantifies the probability of an arbitrary TCP packet being discarded, and the total throughput obtained on the up and down links. Furthermore, quantitative insights can be gained into the throughput that long-lived TCP flows achieve under the joint impact of all aforementioned types of losses. In particular, we find that the wireless channel errors and buffer overflows both lead to throughput unfairness, but that they do so in the opposite direction on the up and down links, respectively. We demonstrate that this insight can be exploited so as to significantly mitigate the throughput unfairness without compromising the total obtainable network throughput.

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2015

Manoj Kumar Panda, Ali, A., Chahed, T., and Altman, E., “Tracking Message Spread in Mobile Delay Tolerant Networks”, IEEE Transactions on Mobile Computing, vol. 14, pp. 1737-1750, 2015.[Abstract]


We consider a delay tolerant network under two message forwarding schemes-a non-replicative direct delivery scheme and a replicative epidemic routing scheme. Our objective is to track the degree of spread of a message in the network. Such estimation can be used for on-line control of message dissemination. With a homogeneous mobility model with pairwise i.i.d. exponential inter-meeting times, we rigorously derive the system dynamic and measurement equations for optimal tracking by a Kalman filter. Moreover, we provide a framework for tracking a large class of processes that can be modeled as density-dependent Markov chains. We also apply the same filter with a heterogeneous mobility, where the aggregate inter-meeting times exhibit a power law with exponential tail as in real-world mobility traces, and show that the performance of the filter is comparable to that with homogeneous mobility. Through customized simulations, we demonstrate the trade-offs and provide several insightful observations on how the number of observers impacts the filter performance.

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2015

Manoj Kumar Panda, Hai Le Vu, Mandjes, M., and Pokhrel, S. Raj, “Performance Analysis of TCP NewReno over a Cellular Last-Mile: Buffer and Channel Losses”, IEEE Transactions on Mobile Computing, vol. 14, pp. 1629-1643, 2015.[Abstract]


TCP NewReno is one of the most widely deployed TCP versions in today's Internet. However, a full understanding of the complex inter-dependencies between the losses due to wireless channel errors and those due to buffer overflows, and their (joint) impact on TCP NewReno's congestion control algorithm in wireless and wired-cum-wireless networks is still lacking. In this paper, we develop a comprehensive analytical model for, and study the performance of, TCP NewReno with a cellular last-mile access, taking into account both types of losses. We assume a frame-level Markovian loss model, and build a model that features the system's basic controllable parameters (such as the number of retransmissions and the buffer size), so as to study how they (jointly) affect the TCP-level throughput. We model certain finer aspects, e.g., correlations in wireless and buffer losses and their cross-correlation. We provide a summary of numerical results highlighting several non-trivial findings. In particular, we demonstrate that there exist optimal (i.e., TCP throughput maximizing) pairs of the number of retransmissions and the buffer size.

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2014

L. Sassatelli, Ali, A., Manoj Kumar Panda, Chahed, T., and Altman, E., “Reliable Transport in Delay-Tolerant Networks With Opportunistic Routing”, IEEE Transactions on Wireless Communications, vol. 13, pp. 5546-5557, 2014.[Abstract]


This paper tackles the issue of reliable transport in delay-tolerant mobile ad hoc networks (DTNs) that are operated by some opportunistic routing algorithm. We propose a reliable transport mechanism that relies on acknowledgements (ACKs) and coding at the source. The various versions of the problem depending on buffer management policies are formulated and a fluid model based on mean-field approximation is derived for the designed reliable transport mechanism. This model allows both the mean file completion time and the energy consumption to be expressed up to the delivery of the last ACK at the source. The accuracy of this model is assessed through numerical simulations and a detailed investigation of the impact of the system parameters on the performance is conducted. We eventually present a joint optimization of the mean completion delay with or without an energy constraint, to identify the optimal set of parameters to use.

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2013

A. Ali, Manoj Kumar Panda, Chahed, T., and Altman, E., “Improving the transport performance in delay tolerant networks by random linear network coding and global acknowledgments”, Ad Hoc Networks, vol. 11, pp. 2567 - 2587, 2013.[Abstract]


We propose and study a new set of enhancement features to improve the performance of reliable transport in Delay Tolerant Networks (DTNs) consisting of both unicast and multicast flows. The improvement in reliability is brought in by a novel Global Selective ACKnowledgment (G-SACK) scheme and random linear network coding. The motivation for using network coding and G-SACKs comes from the observation that one should take the maximum advantage of the contact opportunities which occur quite infrequently in DTNs. Network coding and G-SACKs perform “mixing” of packet and acknowledgment information, respectively, at the contact opportunities and essentially solve the randomness and finite capacity limitations of DTNs. In contrast to earlier work on network coding in DTNs, we observe and explain the gains due to network coding even under an inter-session setting. Our results from extensive simulations of appropriately chosen “minimal” topologies quantify the gains due to each enhancement feature. We show that substantial gains can be achieved by our proposed enhancements that are very simple to implement.

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2013

Manoj Kumar Panda and Kumar, A., “Cell-level modeling of IEEE 802.11 WLANs”, Ad Hoc Networks, vol. 25, Part A, 2013.[Abstract]


We develop a scalable cell-level analytical model for multi-cell infrastructure IEEE 802.11 WLANs under a so-called Pairwise Binary Dependence (PBD) condition. The PBD condition is a geometric property under which the relative locations of the nodes inside a cell do not matter and the network is free of hidden nodes. For a given number of cells, the computational complexity of our cell-level model remains constant even if the number of nodes per cell increases. For the cases of saturated nodes and TCP-controlled long-file downloads, we provide accurate predictions of cell throughputs. Similar to Bonald et al. (Sigmetrics, 2008), we model a multi-cell WLAN under short-file downloads as “a network of processor-sharing queues with state-dependent service rates.” Whereas the state-dependent service rates proposed by Bonald et al. are based only on the number of contending neighbors, we employ state-dependent service rates that incorporate the impact of the overall topology of the network. We propose an effective service rate approximation technique and obtain good approximations for the mean flow transfer delay in each cell. For TCP-controlled downloads where the Access Points (APs) transmit for a much larger fraction of time than the stations (STAs), we consider the case when the APs can sense all the nodes in the neighboring cell, but ≈50% of the STAs in each cell can sense only a subset of STAs in the other cell. Our cell-level model can predict the throughputs quite accurately in this case as well even though the PBD condition does not strictly hold.

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Publication Type: Book Chapter

Year of Publication Title

2013

A. Ali, Manoj Kumar Panda, Sassatelli, L., Chahed, T., and Altman, E., “Reliable Transport in Delay Tolerant Networks”, in Routing in Opportunistic Networks, I. Woungang, Dhurandher, S. Kumar, Anpalagan, A., and Vasilakos, A. V., Eds. New York, NY: Springer New York, 2013, pp. 251–287.[Abstract]


In this paper, we provide a holistic picture of the research efforts towards the design and development of transport protocols for DTN environments. In the first part, we provide an exhaustive and insightful survey of the literature on transport protocols and proposals aimed at DTNs. In the second part, we describe a new reliable transport protocol based on coding. Our proposed protocol is targeted at terrestrial DTN environments consisting of a large number of highly mobile nodes with random mobility. The key idea behind our proposal is that the average dynamics under such a network setting can be captured by a fluid-limit model and the protocol parameters can be optimized based on the fluid-limit model. Through simplified versions of our proposal, we guide the readers in a step-by-step manner through the intricacies of obtaining deterministic fluid-limit models for networks where the dynamics can be stochastically modeled by a continuous time Markov chain with a large state space. We also provide the relevant background material so as to help the readers clearly understand the methodology and enable him/her to apply the technique to their own research problems. More »»

Publication Type: Conference Paper

Year of Publication Title

2011

E. Altman, Estanislao, A., and Manoj Kumar Panda, “Routing games on a circle”, in International Conference on NETwork Games, Control and Optimization (NetGCooP 2011), 2011.[Abstract]


Rings are quite common in both road traffic networks as well as in telecommunication networks. In the road traffic context, we often find rings surrounding towns and cities. Traffic over these rings is either bidirectional or we may find two rings that surround the town carrying traffic in opposite directions (clockwise and anti-clockwise). Telecommunication networks based on rings have been often used both as local area networks as well as in metropolitan area networks and here too we find both bidirectional networks as well as networks consisting of two rings carrying traffic in opposite directions. Each decision maker (e.g. the drivers, in the case of road traffic, and perhaps Internet access providers, in the case of telecommunication) is faced with a simple routing decision: whether to go clockwise or anti-clockwise. Assuming a simple source-destination demand matrix, we analyze this problem as a non-cooperative game and derive several interesting characteristics of the equilibria.

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