Kumar Appaiah

I am an Associate Professor in the Department of Electrical Engineering, Indian Institute of Technology Bombay.

From March 2013 till June 2014, I was working at Qualcomm Research on problems related to visible light communication. Before that, I was a graduate student in the Department of Electrical and Computer Engineering at the University of Texas at Austin. I successfully defended my Ph.D. dissertation in February 2013.

Contact

E-mail: ee.iitb.ac.in, preceded by an @ sign, preceded by akumar

Education

• Ph. D., Electrical and Computer Engineering, The University of Texas at Austin, August 2008 - March 2013
• B.Tech. + M. Tech., Electrical Engineering, Indian Institute of Technology Madras, August 2003 - July 2008

Research

My work involves studying and quantifying the benefits and performance of multiple-input multiple-output (MIMO) concepts in optical and wireless communication systems systems. In particular, I aim to study different signaling as well as signal processing techniques which would enable efficient MIMO communication over optical fibers, as well as wireless communication links.

Current PhD Students

The following (regular) PhD students are working with me currently.

• Komal Ojha, on multiplexing based multimode fiber systems
• Ajith J., on frequency divison multiplexing for fiber systems
• B. Ravi Kumar, on high speed plastic fiber communication systems
• Mehta Parth Harshadbhai, on filters for radar applications (co-guided with Prof. Rajbabu)
• Anil Kumar, on wireless communication systems and information theory (co-guided with Prof. Sibi Raj Pillai)

Useful Links

• Grading Assistant: A web app to assist with assigning grades. Currently customized for IIT Bombay, but easily usable by other universities and colleges. Get the source code. Patches welcome!
• Tips on writing good reports and making good presentations.
• A checklist for reports and papers.

Publications

Journal

• S. M. R. Rani, R. Chopra, K. Appaiah, “Statistical beamforming for cell free massive MIMO under mixed LoS/ NLoS channels,” Physical Communication, vol. 62, no. 1 - 2024 (link)
• P. Mehta, K. Appaiah, R. Velmurugan, D. Pal, “Matrix Unimodular Precoder Interpolation for MIMO-OFDM Wireless Communication Systems,” IEEE Communications Letters, to appear - 2023 (link)
• P. Mehta, K. Appaiah, R. Velmurugan, “Robust Direction-of-Arrival Estimation using Array Feedback Beamforming in Low SNR Scenarios,” IEEE Access, vol. 11, no. 1 - 2023 (link)
• K. Ojha, D. Mishra, K. Appaiah, D. Jain, “Optimizing graded-index few-mode fiber for space division multiplexing,” Optics Express, vol. 31, no. 13 - 2023
• P. Mehta, K. Appaiah, R. Velmurugan, D. Pal, “All-Pass Filter Design Using Unimodular Interpolation,” IEEE Signal Processing Letters, vol. 30, no. 1 - 2023 (link)
• K. P. Anoop, A. M. Reddy, M. S. Bhatia, A. K. Jain, R. Gopalakrishnan, M. Salekin, S. P. Singh, R. V. Satwik, S. Pulapadi, C. Bobade, I. S. Kumar, S. Gopalakrishnan, K. Appaiah, N. Rangaraj, M. N. Belur, “Rationalized Timetabling Using a Simulation Tool: A Paradigm Shift in Indian Railways,” INFORMS Journal on Applied Analytics, vol. 53, no. 4 - 2023 (link)
• A. S. Bharath, D. S. Gaharwar, K. Appaiah, D. Pal, “Design of discrete-time matrix all-pass filters using subspace Nevanlinna pick interpolation,” Signal Processing, vol. 204, no. 1 - 2023 (link)
• N. Kolla, K. Appaiah, R. Chopra, “Efficient parameterized precoder tracking in slowly time-varying MIMO channels,” IEEE Communications Letters, vol. 27, no. 1 - 2022 (link)
• A. Kumar, K. Appaiah, S. B. Pillai, “On the Sum Capacity Achieving Precoders and their CSI Requirements for MIMO-BC,” IEEE Communications Letters, vol. 26, no. 7 - 2022 (link)
• I. M. Baby, K. Appaiah, R. Chopra, “Optimal Channel Tracking and Power Allocation for Time Varying FDD Massive MIMO Systems,” IEEE Transactions on Communications, vol. 70, no. 2 - 2022 (link)
• M. B. Patil, R. D. Korgaonkar, K. Appaiah, “GSEIM: A General-purpose Simulator with Explicit and Implicit Methods,” Sadhana, vol. 46, no. 1 - 2021 (link)
• A. Radhakrishnan, R. Prasad, K. Appaiah, “Efficient multiplexing using delayed CSI in few-mode fiber links,” Optical Fiber Technology, vol. 66, no. 1 - 2021 (link)
• A. E. Bangera, K. Appaiah, “Quantum-confined ultra-wideband Si-based absorbers by a non-lithographic approach,” Solar Energy Materials and Solar Cells, vol. 230, no. 1 - 2021 (link)
• A. Miryala, I. M. Baby, K. Appaiah, S. B. Pillai, “A Post-Coder Feedback Approach to Overcome Training Asymmetry in MIMO-TDD,” IEEE Transactions on Vehicular Technology, vol. 70, no. 6 - 2021 (link)
• R. Arjun, H. Shah, S. Dhua, P. M. Krishna, K. Appaiah, V. M. Gadre, “Low Complexity FBMC for wireless MIMO systems,” Elsevier Physical Communications, vol. 47, no. 1 - 2021 (link)
• S. Nijhawan, A. Gupta, K. Appaiah, R. Vaze, N. Karamchandani, “Flag manifold based precoder interpolation techniques for MIMO-OFDM systems,” IEEE Transactions on Communications, vol. 69, no. 7 - 2021 (link)
• H. Rahman, A. Vinayachandran, S. R. B. Pillai, K. Appaiah, R. Vaze, N. Kashyap, “Deadline Constrained Packet Scheduling in the Presence of an Energy Harvesting Jammer,” IEEE Transactions on Green Communications and Networking, vol. 5, no. 1 - 2021 (link)
• A. E. Bangera, K. Appaiah, “Three-Dimensional Grids of Optimized Ti-Compounds on Si for Ultra-Wideband Optical Absorption,” ACS Applied Materials & Interfaces, vol. 12, no. 35 - 2020 (link)
• M. Madan, A. Gupta, K. Appaiah, “Scalar Feedback based Joint Time-Frequency Precoder Interpolation for MIMO-OFDM Systems,” IEEE Wireless Communications Letters, vol. 9, no. 9 - 2020 (link)
• A. Radhakrishnan, K. Appaiah, “Mode Subset Selection and Feedback for Low Complexity Equalization in DWDM MMF Links,” IEEE Communications Letters, vol. 24, no. 8 - 2020 (link)
• A. E. Bangera, K. Appaiah, “Tunable wettability and prediction of total surface energy for nanocoatings: An empirical model,” Surface and Coatings Technology, vol. 383, no. 1 - 2020 (link)
• K. Appaiah, D. Pal, “All-Pass Filter Design Using Blaschke Interpolation,” IEEE Signal Processing Letters, vol. 27, no. 1 - 2020 (link)
• A. E. Bangera, K. Appaiah, “A conditional justification for the determination of surface energy of solids using contact angle methods,” Materials Chemistry and Physics, vol. 234, no. 1 - 2019 (link)
• J. C. Jacob, K. Appaiah, “Mode multiplexing using Principal Modes in Few-mode Fiber Links with Delayed Feedback,” IEEE Communications Letters, vol. 23, no. 8 - 2019 (link)
• R. Prasad, K. Appaiah, “Impact of modulation bandwidth on multiplexing using principal modes in MMF links,” Optics Express, vol. 26, no. 2 - 2018 (link)
• J. C. Jacob, R. Mishra, K. Appaiah, “Quantization and Feedback of Principal Modes for Dispersion Mitigation and Multiplexing in Multimode Fibers,” IEEE Transactions on Communications, vol. 64, no. 12 - 2016 (link)
• K. Appaiah, S. Vishwanath, S. R. Bank, “Impact of Fiber Core Diameter on Dispersion and Multiplexing in Multimode-Fiber Links,” OSA Optics Express, vol. 22, no. 14 - 2014 (link)
• K. Appaiah, S. Zisman, A. K. Das, S. Vishwanath, S. R. Bank, “Analysis of Laser and Detector Placement in Incoherent MIMO Multimode Fiber Systems,” IEEE/OSA Journal of Optical Communications and Networking, vol. 6, no. 4 - 2014 (link)
• K. Appaiah, S. Vishwanath, S. R. Bank, “Vector Intensity-Modulation and Channel State Feedback for Multimode Fiber Optic Links,” IEEE Transactions on Communications, vol. 61, no. 7 - 2013 (link)
• K. Appaiah, R. Salas, S. Vishwanath, S. R. Bank, “Offset Coupling, Feedback, and Spatial Multiplexing in 4 × 4 Incoherent-MIMO Multimode Fiber Links,” Journal of Lightwave Technology, vol. 31, no. 17 - 2013 (link)
• K. Appaiah, S. Vishwanath, S. R. Bank, “Device Design and Signal Processing for Multiple-Input Multiple-Output Multimode Fiber Links (Invited),” Proc. of SPIE, vol. 8267, no. 1 - 2012
• K. Appaiah, S. Vishwanath, S. R. Bank, “Advanced Modulation and Multiple-Input Multiple-Output for Multimode Fiber Links,” IEEE Photonics Technology Letters, vol. 23, no. 20 - 2011 (link)

Conference

• N. Murali K. Appaiah, “Keyboard Side Channel Attacks on Smartphones Using Sensor Fusion,” 2018 IEEE Global Communications Conference (GLOBECOM) - 2018 (link)
• A. Kumar, K. Appaiah, S. Raj. B. Pillai, “On the Ergodic Sum Capacity of Multi-User MIMO with Distributed Transmitter,” 2023 IEEE International Conference on Communications (ICC) - 2023 (link)
• R. Dinkar. Kamble, K. Appaiah, “Impact of Component Sensitivity on Biquad Equalizer based Plastic Optical Fiber Links,” 2023 International Conference for Advancement in Technology (ICONAT) - 2023 (link)
• D. Mishra, K. Ojha, K. Appaiah, D. Jain, “Germania Glass-Based Negative-Curvature Hollow-Core Fiber for Mid-IR Applications,” Frontiers in Optics - 2022 (link)
• R. D. Kamble, K. Appaiah, “Biquad filter based equalization for PMMA SI-POF links,” 2022 IEEE International Conference on Signal Processing and Communications (SPCOM) - 2022 (link)
• K. Ojha, K. Appaiah, “Feedback based Compensation of Second Order Modal Dispersion in Principal Mode based Multiplexed MMF Links,” 2022 National Conference on Communications (NCC) - 2022 (link)
• A. Radhakrishnan, K. Appaiah, “Multiplexed Principal Modes in Few-Mode Fiber Links With Limited Delayed Feedback,” 2022 National Conference on Communications (NCC) - 2022 (link)
• H. Rahman, A. Vinayachandran, S. B. Pillai, K. Appaiah, R. Vaze, “A Game Theoretic Model for Deadline Constrained Packet Scheduling with an Energy Harvesting Jammer,” 2020 International Conference on Computing, Networking and Communications (ICNC) - 2020 (link)
• P. Sankhe, S. Azim, S. Goyal, T. Choudhary, K. Appaiah, S. Srikant, “Indoor Distance Estimation using LSTMs over WLAN Network,” 2019 16th Workshop on Positioning, Navigation and Communications (WPNC) - 2019 (link)
• M. Khaturia, K. Appaiah, A. Karandikar, “On Efficient Wireless Backhaul Planning for the Frugal 5G Network,” 2019 IEEE Wireless Communications and Networking Conference Workshop (WCNCW) - 2019 (link)
• P. Agrawal, K. Appaiah, “Kalman Filter Based Channel Tracking for Precoded GFDM Systems,” TENCON 2019 - 2019 IEEE Region 10 Conference - 2019 (link)
• A. Bangera, K. Appaiah, S. Chakrabarti, “Surface engineering using compounds of titanium nanocoatings for silicon based optical devices,” SPIE Photonics West - 2019 (link)
• A. Gupta, K. Appaiah, R. Vaze, “Predictive Quantization and Joint Time-Frequency Interpolation technique for MIMO-OFDM precoding,” 2019 IEEE International Conference on Communications (ICC) - 2019
• V. Arya, K. Appaiah, “Kalman Filter Based Tracking for Channel Aging in Massive MIMO Systems,” 2018 International Conference on Signal Processing and Communications (SPCOM) - 2018
• R. Prasad, K. Appaiah, “Utility of Delayed CSI Feedback in Mode Division Multiplexed Multimode Fiber Links,” 2018 International Conference on Signal Processing and Communications (SPCOM) - 2018
• J. C. Jacob, K. Appaiah, “Limited Feedback and Interpolation of Principal Modes in Spatially Multiplexed WDM Fiber Links,” 2018 International Conference on Signal Processing and Communications (SPCOM) - 2018
• R. Arjun, A. Sukhwani, K. Appaiah, V. Gadre, “Non-orthogonal Transmultiplexers for FBMC with Controlled ISI,” 2018 International Conference on Signal Processing and Communications (SPCOM) - 2018
• J. C. Jacob, K. Appaiah, “Multiplexing using principal modes in spliced MMFs with mode dependent losses,” 2017 Twenty-third National Conference on Communications (NCC) - 2017
• R. Mishra, J. C. Jacob, K. Appaiah, “Quantization and Feedback of Principal Modes for High Speed Multimode Fiber Links,” IEEE International Conference on Communications (ICC), Kuala Lumpur - 2016 (link)
• R. Mishra, J. C. Jacob, K. Appaiah, “Limited feedback of principal modes for high speed multimode fiber links,” 2015 Workshop on Recent Advances in Photonics (WRAP), Bengaluru - 2015 (link)
• K. S. Sanila, K. Appaiah, “Low Complexity Equalization Using Mode-Subset Selection in MIMO Multimode Fiber Links,” IEEE Global Communications Conference (GLOBECOM), San Diego, CA - 2015 (link)
• K. Appaiah, “Detector and Mode Subset Selection for DSP based Multimode Fiber Links (Invited),” Twenty First National Conference on Communications (NCC), Mumbai - 2015 (link)
• K. Appaiah, R. Salas, S. Vishwanath, S. R. Bank, “Enhancing Data Rates in Graded-Index Multimode Fibers with Offset Coupling and Multiplexing,” Optical Fiber Communication Conference, Anaheim, CA - 2013 (link)
• K. Appaiah, S. Zisman, S. Vishwanath, S. R. Bank, “Analysis of Laser and Detector Placement in MIMO Multimode Optical Fiber Systems,” IEEE International Conference on Communications (ICC), Ottawa, ON - 2012 (link)
• K. Appaiah, S. Vishwanath, S. R. Bank, “Device Design and Signal Processing for Multiple-Input Multiple-Output Multimode Fiber Links (Invited),” SPIE OPTO, San Francisco, CA - 2012
• K. Appaiah, S. Zisman, S. Vishwanath, S. Bank, “Dynamic Detector Selection for Multiple-Input Multiple-Output (MIMO) Multimode Fiber Links,” CLEO: Science and Innovations, San Jose, CA - 2012 (link)
• O. O. Koyluoglu, K. Appaiah, H. Si, S. Vishwanath, “Expansion Coding: Achieving the Capacity of an AEN Channel,” IEEE International Symposium on Information Theory Proceedings (ISIT), Boston, MA - 2012 (link)
• K. Appaiah, O. O. Koyluoglu, S. Vishwanath, “Polar Alignment for Interference Networks,” 49th Annual Allerton Conference on Communication, Control, and Computing, Allerton, IL - 2011 (link)
• K. Appaiah, S. Vishwanath, S. R. Bank, “Multiple-Input Multiple-Output with Predistortion and Signal Processing for Multimode Fiber Links,” CLEO: Science and Innovations, Baltimore, MD - 2011 (link)
• K. Appaiah, A. Ashikhmin, T. L. Marzetta, “Pilot Contamination Reduction in Multi-User TDD Systems,” IEEE International Conference on Communications (ICC), Cape Town, South Africa - 2010 (link)