Senior Engineer at Qualcomm

### Scholarly works

###### Submitted
1. I. A. Kadampot, M. Tahmasbi, and M. R. Bloch, “Multilevel-Coded Pulse-Position Modulation for Covert Communications over Binary-Input Discrete Memoryless Channels.” submitted to IEEE Transactions on Information Theory, Nov. 2018.

We develop a low-complexity coding scheme to achieve covert communications over binary-input discrete memoryless channels (BI-DMCs). We circumvent the impossibility of covert communication with linear codes by introducing non-linearity through the use of pulse position modulation (PPM) and multilevel coding (MLC). We show that the MLC-PPM scheme exhibits many appealing properties; in particular, the channel at a given index level remains stationary as the number of level increases, which allows one to use families of channel capacity- and channel resolvability-achieving codes to concretely instantiate the covert communication scheme.

@misc{Kadampot2018a,
author = {Kadampot, Ishaque Ashar and Tahmasbi, Mehrdad and Bloch, Matthieu R},
title = {Multilevel-Coded Pulse-Position Modulation for Covert Communications over Binary-Input Discrete Memoryless Channels},
howpublished = {submitted to \emph{IEEE Transactions on Information Theory}},
month = nov,
year = {2018},
eprint = {1811.09695}
}


###### Conference proceedings
1. I. Kadampot, M. Tahmasbsi, and M. R. Bloch, “Forward Reconciliation for Covert Key Generation,” in Proc. of IEEE Information Theory Workshop, Visby, Sweden, Aug. 2019, pp. 1–5.

@inproceedings{Kadampot2019a,
booktitle = {Proc. of IEEE Information Theory Workshop},
title = {Forward Reconciliation for Covert Key Generation},
year = {2019},
month = aug,
pages = {1--5},
doi = {10.1109/ITW44776.2019.8989274},
howpublished = {accepted to \emph{IEEE Information Theory Workshop}}
}


2. I. A. Kadampot, M. Tahmasbi, and M. R. Bloch, “Codes for Covert Communication over Additive White Gaussian Noise Channels,” in Proc. of IEEE International Symposium on Information Theory, Paris, France, Jul. 2019, pp. 977–981.

We propose a coding scheme for covert communication over additive white Gaussian noise channels, which extends a previous construction for discrete memoryless channels. We first show how sparse signaling with On-Off keying fails to achieve the covert capacity but that a modification allowing the use of binary phase-shift keying for "on" symbols recovers the loss. We then construct a modified pulse-position modulation scheme that, combined with multilevel coding, can achieve the covert capacity with low-complexity error-control codes. The main contribution of this work is to reconcile the tension between diffuse and sparse signaling suggested by earlier information-theoretic results.

@inproceedings{Kadampot2019,
author = {Kadampot, Ishaque Ashar and Tahmasbi, Mehrdad and Bloch, Matthieu R},
title = {Codes for Covert Communication over Additive White Gaussian Noise Channels},
booktitle = {Proc. of IEEE International Symposium on Information Theory},
year = {2019},
pages = {977-981},
month = jul,
doi = {10.1109/ISIT.2019.8849662},
howpublished = {accepted to \emph{IEEE International Symposium on Information Theory}}
}


3. I. A. Kadampot, M. Tahmasbi, and M. R. Bloch, “Multilevel-Coded Pulse Position Modulation for Covert Communications,” in Proc. of IEEE International Symposium on Information Theory, Vail, CO, Jun. 2018, pp. 1864–1868.

We develop a low-complexity coding scheme to achieve covert communications over binary symmetric channels. We circumvent the impossibility of covert communication with linear codes by introducing non-linearity through the use of pulse-position modulation (PPM) and multilevel coding (MLC). We show that the MLC-PPM scheme exhibits many appealing properties, in particular, the channel at a given index level remains the same as the number of level increases, which allows one to use families of capacity- and resolvability-achieving codes to concretely instantiate the covert communication scheme.

@inproceedings{Kadampot2018,
author = {Kadampot, Ishaque Ashar and Tahmasbi, Mehrdad and Bloch, Matthieu R.},
title = {Multilevel-Coded Pulse Position Modulation for Covert Communications},
booktitle = {Proc. of IEEE International Symposium on Information Theory},
year = {2018},
pages = {1864--1868},
month = jun,
doi = {10.1109/ISIT.2018.8437587},
groups = {Steganography and covert communications},
howpublished = {accepted to \emph{IEEE International Symposium on Information Theory}}
}


4. I. A. Kadampot and M. R. Bloch, “Coordination with Clustered Common Randomness in a Three-Terminal Line Network,” in Proc. of IEEE International Symposium on Information Theory, Aachen, Germany, Jun. 2017, pp. 1828–1832.

To achieve strong coordination in a network, nodes benefit from access to a source of common randomness. Most studies pertaining to strong coordination assume the existence of a source of common randomness accessible to all nodes in the network. This assumption, however, is not practical in a decentralized network. We analyze the problem of strong coordination in a three-terminal line network with common randomness available only at the first two nodes and assume that the actions of the first node are specified by an external agent. We use coding schemes developed for channel resolvability codes to characterize the strong coordination capacity region when the intermediate node is operating in a functional mode. A comparison of our coordination capacity region with a case in which all nodes have access to a common randomness shows that we have to increase the communication rate between the second and the third nodes to achieve the same coordination distribution.

@inproceedings{Kadampot2017,
author = {Kadampot, Ishaque Ashar and Bloch, Matthieu R},
title = {Coordination with Clustered Common Randomness in a Three-Terminal Line Network},
booktitle = {Proc. of IEEE International Symposium on Information Theory},
year = {2017},
pages = {1828--1832},
month = jun,
doi = {10.1109/ISIT.2017.8006845},
groups = {Coordination of networks},
howpublished = {accepted to \emph{IEEE International Symposium on Information Theory}}
}


5. K. S. K. Arumugam, I. A. Kadampot, M. Tahmasbi, S. Shah, M. Bloch, and S. Pokutta, “Modulation recognition using side information and hybrid learning,” in Proc. IEEE Int. Symp. Dynamic Spectrum Access Networks (DySPAN), Piscataway, NJ, Mar. 2017, pp. 1–2.

Recent applications of machine learning to modulation recognition have demonstrated the potential of deep learning to achieve state-of-the-art performance. We propose to further extend this approach by using flexible time-space decompositions that are more in line with the actual learning task, as well as integrate side-information, such as higher order moments, directly into the training process. Our promising preliminary results suggest that there are many more benefits to be reaped from such approaches.

@inproceedings{Arumugam2017a,
author = {Arumugam, K. S. Kumar and Kadampot, I. A. and Tahmasbi, M. and Shah, S. and Bloch, M. and Pokutta, S.},
title = {Modulation recognition using side information and hybrid learning},
booktitle = {Proc. IEEE Int. Symp. Dynamic Spectrum Access Networks (DySPAN)},
year = {2017},
pages = {1--2},