Bio

I am a second-year PhD student advised by Prof. Vamsi Addanki. My research revolves around photonic interconnects for data center networks. My interests lie broadly in systems design, hardware design, and computer networking. I am particularly interested in the intersection of networking systems and hardware architectures, and in building high-performance interconnects that enable efficient communication between compute, memory, and accelerator resources in large-scale data centers.

Recent Publications

NSDI ’27
Vermilion: A Traffic-Aware Reconfigurable Optical Interconnect with Formal Throughput Guarantees
Vamsi Addanki, Deeksha P Rao, Goran Dario Knabe, Chen Avin, and Stefan Schmid.
24th USENIX Symposium on Networked Systems Design and Implementation (NSDI 27), Providence, RI, 2027.
Abstract BibTeX

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The increasing gap between datacenter traffic volume and the capacity of electrical switches has driven the development of reconfigurable network designs utilizing optical circuit switching. Recent advancements, particularly those featuring periodic fixed-duration reconfigurations, have achieved practical end-to-end delays of just a few microseconds. However, current designs rely on multi-hop routing to enhance utilization, which can lead to a significant reduction in worst-case throughput and added overhead from congestion control and routing complexity. These factors pose significant operational challenges for the large-scale deployment of these technologies.
We present Vermilion, a reconfigurable optical interconnect that breaks the throughput barrier of existing periodic reconfigurable networks, without the need for multi-hop routing — thus eliminating congestion control and simplifying routing to direct communication. Vermilion adopts a traffic-aware approach while retaining the simplicity of periodic fixed-duration reconfigurations, similar to RotorNet. We formally establish throughput bounds for Vermilion, demonstrating that it achieves at least 33% more throughput in the worst-case compared to existing designs. The key innovation of Vermilion is its short traffic-aware periodic schedule, derived using a matrix rounding technique. This schedule is then combined with a traffic-oblivious periodic schedule to efficiently manage any residual traffic. Our evaluation results support our theoretical findings, revealing significant performance gains for datacenter workloads.
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```
@inproceedings{vermilionNsdi27,
  author = {Addanki, Vamsi and Rao, Deeksha P and Knabe, Goran Dario and Avin, Chen and Schmid, Stefan},
  title = {Vermilion: A Traffic-Aware Reconfigurable Optical Interconnect with Formal Throughput Guarantees},
  booktitle = {24th USENIX Symposium on Networked Systems Design and Implementation (NSDI 27)},
  year = {2027},
  address = {Providence, RI},
  publisher = {USENIX Association}
}
```
HotNets ’26
What Is Reconfiguration Delay, Really? An End-to-End View of Photonic Switching
Deeksha P Rao and Vamsi Addanki.
Proceedings of the 25th ACM Workshop on Hot Topics in Networks, Salt Lake City, Utah, USA, 2026.
Abstract BibTeX

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Reconfiguration delay is a defining systems parameter of photonic switching. Yet, it is almost universally modeled as a single constant in network design and circuit scheduling algorithms, namely the optical switching time reported by the device. We argue that this abstraction is no longer sufficient. From an application’s perspective, reconfiguration begins when a new circuit is requested and ends only when communication resumes over the new path. The latency observed by the application spans an end-to-end critical path across multiple hardware and software components, not just the optical switch.
This paper asks a simple question: what is reconfiguration delay, really? We argue that it should be understood as an end-to-end systems property rather than a device property. To make this concrete, we dissect the critical path of a circuit transition, spanning host-to-controller communication, controller processing, electrical signaling, and optical switching. Our measurements show that optical switching itself accounts for only a small fraction of the end-to-end latency, even before considering transceiver recovery and receiver-side reactions. This perspective raises a fundamental systems question: if most of the end-to-end delay lies outside the switch fabric, what should future photonic switching systems optimize? We conclude by outlining a research agenda for reducing end-to-end reconfiguration delay across the hardware–software stack.
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```
@inproceedings{photonicsreconfigurationhotnets26,
  author = {Rao, Deeksha P and Addanki, Vamsi},
  title = {What Is Reconfiguration Delay, Really? An End-to-End View of Photonic Switching},
  year = {2026},
  booktitle = {Proceedings of the 25th ACM Workshop on Hot Topics in Networks}
}
```
Networking ’25
LoRa++: Mixed Up-Down CSS Modulation for Enhanced Scalability and Data Rate in LPWANs
Shrutkirthi S. Godkhindi, Deeksha P. Rao, R. Venkatesha Prasad, and T. V. Prabhakar.
IFIP Networking Conference (IFIP Networking) and Workshops, Limassol, Cyprus, 2025.
PDF Abstract BibTeX

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LoRa has been widely used for various Internet of Things (IoT) applications because of its simplicity & ease of deployment. However, LoRa suffers from low data rates and higher collisions. We propose & implement a mixed index modulation scheme LoRa++ that carries two additional bits per symbol in each of the supported spreading factors. We do this by introducing UpDown and DownUp chirps to augment the existing Up and Down chirps. Modulation and demodulation are non-trivial, but we can easily incorporate them within the existing LoRa nodes and gateways. Our results show that SNR requirements for LoRa++ demodulation are within the 1-2 dB range from conventional LoRa. Moreover, LoRa++ performs equally well for inter-SF interference. Our simulation results show that LoRa++ can accommodate more nodes due to the reduced time on air. Finally, we show that our hardware implementation on USRP is simple, and the results validate the performance of LoRa++. The performance of the new scheme in terms of BER is on par with that of conventional LoRa.
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```
@inproceedings{Godkhindi2025LoRaMU,
  title = {LoRa++: Mixed Up-Down CSS Modulation for Enhanced Scalability and Data Rate in LPWANs},
  author = {Godkhindi, Shrutkirthi S. and Rao, Deeksha P. and Prasad, R. Venkatesha and Prabhakar, T. V.},
  booktitle = {IFIP Networking Conference (IFIP Networking) and Workshops},
  year = {2025},
  url = {https://networking.ifip.org/2025/images/Net25_papers/1571127065.pdf}
}
```
Ad Hoc ’24
Dy-MAC: Implementation of dynamic MAC stack for IEEE 802.15.4e-TSCH
Deeksha P. Rao, Shrutkirthi S. Godkhindi, Abhigna V. Kumar, and T.V. Prabhakar.
Ad Hoc Networks, 2024.
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This paper presents the lessons learnt in the implementation of IEEE 802.15.4e-Time Slotted Channel Hopping (TSCH) Medium Access Control (MAC) protocol on commercially available hardware. Our MAC Application programming Interface (API) called the Dy-MAC is agnostic to the PHY layer and is coded on a ARM cortex M4. MAC functions such as TDMA, FDMA, frame counter, channel access, synchronization and PAN formation are abstracted as part of this API. Dy-MAC is demonstrated for 2.4GHz with O-QPSK modulation and 868MHz with SUN FSK modulation. Furthermore, the API supports star, mesh and tree network to provide flexible topologies in factory environment. Our experiments show that for a 76 byte payload, the TSCH Dy-MAC provides ∼ 99% packet delivery ratio (PDR) for 26ms timeslot with SUN FSK PHY and ∼ 97% PDR for 10ms timeslot with O-QPSK PHY. To maintain synchronization over the entire network, we implemented algorithms to successfully communicate between fast and slow nodes. Resilience to interference and range with packet delivery ratio is evaluated. We consolidate our implementation in terms of 10 lessons that were learnt in building the Dy-MAC protocol.
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```
@article{RAO2024103268,
  title = {Dy-MAC: Implementation of dynamic MAC stack for IEEE 802.15.4e-TSCH},
  journal = {Ad Hoc Networks},
  volume = {152},
  pages = {103268},
  year = {2024},
  issn = {1570-8705},
  doi = {https://doi.org/10.1016/j.adhoc.2023.103268},
  url = {https://www.sciencedirect.com/science/article/pii/S1570870523001889},
  author = {Rao, Deeksha P. and Godkhindi, Shrutkirthi S. and Kumar, Abhigna V. and Prabhakar, T.V.},
  keywords = {Frequency hopping, IEEE 802.15.4e, IIoT, TSCH, Time-synchronization, Channel hopping, Node re-joining, SPI, Information element (IE), Finite state machine (FSM), API}
}
```
Comsnets ’23
Lessons Learnt From the Implementation of the IEEE 802.15.4e-TSCH MAC
Ipsita Sanyal, Deeksha P Rao, Rakshana Gunasekaran, Sachin SM, and T V Prabhakar.
2023 15th International Conference on COMmunication Systems & NETworkS (COMSNETS), 2023.
PDF Abstract BibTeX

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In this work, we implement the IEEE 802.15.4e-Time Slotted Channel Hopping (TSCH) Medium Access Control (MAC) protocol software stack on standard hardware. An Application Programming Interfaces (API) support and ready to deploy star network is built and tested. The interfacing between micro-controller and radio uses the Serial Peripheral Interface (SPI) bus. Our implementation reveals that over 50% of the time overhead is SPI communication. To maintain synchronisation over the entire network, we implemented algorithms to successfully communicate between fast and slow nodes. Resilience to interference and packet error ratio is evaluated. We consolidate our implementation in terms of 6 lessons that were learnt in building the MAC protocol.
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```
@inproceedings{10041267,
  author = {Sanyal, Ipsita and Rao, Deeksha P and Gunasekaran, Rakshana and SM, Sachin and Prabhakar, T V},
  booktitle = {2023 15th International Conference on COMmunication Systems & NETworkS (COMSNETS)},
  title = {Lessons Learnt From the Implementation of the IEEE 802.15.4e-TSCH MAC},
  year = {2023},
  volume = {},
  number = {},
  pages = {658-666},
  keywords = {IEEE 802.15 Standard;Stars;Spread spectrum communication;Interference;Media Access Protocol;Hardware;Synchronization;Frequency hopping;IEEE 802.15.4e;IIoT;Time synchronization;TSCH;SPI;Information Element (IE)},
  doi = {10.1109/COMSNETS56262.2023.10041267},
  issn = {2155-2509}
}
```
NKCon ’22
Implementation of Physical Layer Encryption For Wireless Communication System
Bhargava V Desai, Yadunand G Kamath, Deeksha P Rao, Anusha S, and Sanjay M Belgaonkar.
2022 IEEE North Karnataka Subsection Flagship International Conference (NKCon), 2022.
PDF Abstract BibTeX

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The Adoption of Wireless Communication Systems has massively impacted everyday lives of the people. Securing privacy is an important aspect to consider in wireless communication systems due to their broadcast nature. The data transferred between two parties need to be protected by a process of encryption, which helps maintain its privacy. Encryption is usually only applied to the upper layers of the OSI model, which may be sufficient to protect the actual contents of the message. However, the Physical Layer (PHY) signal remains unprotected and consequently exposes critical information such as data rates, channel type, channel bandwidth, modulation, number of physical channels and traffic statistics, which can be used to deduce the channel capacity, transmission equipment and importance of the message. This issue can be mended by performing Physical Layer Encryption (PLE) to provide an additional layer of security. In this paper, a comparative analysis of different PLE techniques is provided along with their simulations. Additionally, these PLE techniques are also implemented in the wireless communication systems on the GNU Radio platform, and suitable output waveforms are illustrated with details.
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```
@inproceedings{10126923,
  author = {Desai, Bhargava V and Kamath, Yadunand G and Rao, Deeksha P and S, Anusha and Belgaonkar, Sanjay M},
  booktitle = {2022 IEEE North Karnataka Subsection Flagship International Conference (NKCon)},
  title = {Implementation of Physical Layer Encryption For Wireless Communication System},
  year = {2022},
  volume = {},
  number = {},
  pages = {1-7},
  keywords = {Wireless communication;Privacy;Data privacy;Channel capacity;Modulation;Bandwidth;Physical layer;Wireless Communication;Communication System Security;Physical Layer Encryption (PLE)},
  doi = {10.1109/NKCon56289.2022.10126923},
  issn = {}
}
```