arXiv subjects

Siddhartha S. Borkotoky

Publications and source records attributed to Siddhartha S. Borkotoky.

10 recordsLinked to original sources

arXiv2026

Time-Constrained Erasure Correction for Data Recovery in UAV-Aided IoT

We propose data-recovery schemes to improve the uplink reliability of Internet of Things (IoT) networks in which a gateway mounted on an unmanned aerial vehicle (UAV) collects data from sensor nodes on the ground. The proposed techniques employ fountain coding and message replication to correct frame erasures on the sensor-to-UAV links. A salient feature of the proposed schemes is their adaptive selection of the redundancy amount depending on the contact times between a sensor and the UAV. We illustrate our design philosophy for the special case of a network in which wake-up radios (WuRs) are used for activating the sensors upon the UAV's arrival, and the sensor-to-UAV data transfer employs the Long Range (LoRa) communication technology with random access.

cs.NI↗

arXiv2026

Accelerating Update Broadcasts Over LoRaWAN Downlink via D2D Cooperation

Broadcast distribution of updates (e.g., security patches, machine learning models) from a server to end devices (EDs) is a critical requirement in the Internet of Things (IoT). In this paper, we consider the problem of reliable over-the-air broadcast of updates in Long Range Wide Area Networks (LoRaWANs). Existing broadcast techniques for LoRaWANs suffer from long delivery delays due to low data rates and duty-cycle constraints. We address this problem by proposing a device-level cooperative mechanism, in which updated EDs broadcast a few update fragments to accelerate delivery to their neighbors. We demonstrate large reductions in the delivery time compared to conventional methods. For instance, in a 400-node network spanning 1 km radius and operating at 1% duty-cycle, the proposed scheme reduces the time required to deliver a 10 kilobyte update to an ED at the network's edge from 42 hours to 45 minutes. The proposed solution thus provides a pathway toward improved security and efficient realization of edge intelligence in LoRaWAN IoT.

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arXiv2025

Federated Learning Over LoRa Networks: Simulator Design and Performance Evaluation

Federated learning (FL) over long-range (LoRa) low-power wide area networks faces unique challenges due to limited bandwidth, interference, and strict duty-cycle constraints. We develop a Python-based simulator that integrates and extends the Flower and LoRaSim frameworks to evaluate centralized FL over LoRa networks. The simulator employs a detailed link-level model for FL update transfer over LoRa channels, capturing LoRa's receiver sensitivity, interference characteristics, block-fading effects, and constraints on the maximum transmission unit. It supports update sparsification, quantization, compression, forward frame-erasure correction (FEC), and duty cycling. Numerical results illustrate the impact of transmission parameters (spreading factor, FEC rate) and interference on FL performance. Demonstrating the critical role of FEC in enabling FL over LoRa networks, we perform an in-depth evaluation of the impact of FEC on FL convergence and device airtime, providing insights for communication protocol design for FL over LoRa networks.

cs.NI↗

arXiv2025

Balancing the Energy Consumption and Latency of Over-the-Air Firmware Updates in LoRaWAN

Over-the-air firmware updates are crucial for mitigating security threats and maintaining up-to-date device functionality in Long Range Wide Area Networks (LoRaWANs). LoRaWAN end devices are usually energy-constrained, and LoRaWAN transmissions are subject to duty-cycle restrictions. Consequently, controlling the energy expenditure and update-delivery latency of FUOTA are key challenges. We propose a flexible scheme that achieves a tunable trade-off between the energy consumption and delivery delay. The scheme employs the LoRa spreading factors sequentially to transmit update-carrying frames, sending a fixed number of frames with a given spreading factor before moving to the next. By adjusting the smallest spreading factor to be used and the number of transmissions per spreading factor, a suitable energy-delay trade-off can be achieved. Thus, time-sensitive updates, such as security patches, may be sent with a low-delay-high-energy setting, whereas a more energy-efficient but higher-delay setting may be used for non-critical updates.

cs.NI↗

arXiv2025

Message Replication for Improving Reliability of LR-FHSS Direct-to-Satellite IoT

Long-range frequency-hopping spread spectrum (LR-FHSS) promises to enhance network capacity by integrating frequency hopping into existing Long Range Wide Area Networks (LoRaWANs). Due to its simplicity and scalability, LR-FHSS has generated significant interest as a potential candidate for direct-to-satellite IoT (D2S-IoT) applications. This paper explores methods to improve the reliability of data transfer on the uplink (i.e., from terrestrial IoT nodes to satellite) of LR-FHSS D2S-IoT networks. Because D2S-IoT networks are expected to support large numbers of potentially uncoordinated IoT devices per satellite, acknowledgment-cum-retransmission-aided reliability mechanisms are not suitable due to their lack of scalability. We therefore leverage message-replication, wherein every application-layer message is transmitted multiple times to improve the probability of reception without the use of receiver acknowledgments. We propose two message-replication schemes. One scheme is based on conventional replication, where multiple replicas of a message are transmitted, each as a separate link-layer frame. In the other scheme, multiple copies of a message is included in the payload of a single link-layer frame. We show that both techniques improve LR-FHSS reliability. Which method is more suitable depends on the network's traffic characteristics. We provide guidelines to choose the optimal method.

cs.NI↗

arXiv2023

Leveraging Wake-Up Radios in UAV-Aided LoRa Networks: Some Preliminary Results on a Random-Access Scheme

We present a transmission scheme aimed at integrating wake-up radios (WuR) into LoRa sensor networks featuring UAV-mounted gateways. The sensors are informed of the UAV's arrival with the help of WuR, followed by sensor-to-UAV data transfer with frequency and spreading-factor hopping. The proposed scheme provides significant energy savings at the sensors while maintaining similar reliability levels compared to a scheme in which Class B LoRa beacons are used to perfectly synchronize the sensors with the UAV's data-collection window.

cs.NI↗

arXiv2022

Making the Most of Sporadic Feedback: Low-Complexity Application-Layer Coding for Data Recovery in the Internet of Things

We propose application-layer coding schemes to recover lost data in delay-sensitive uplink (sensor-to-gateway) communications in the Internet of Things. Built on an approach that combines retransmissions and forward erasure correction, the proposed schemes' salient features include low computational complexity and the ability to exploit sporadic receiver feedback for efficient data recovery. Reduced complexity is achieved by keeping the number of coded transmissions as low as possible and by devising a mechanism to compute the optimal degree of a coded packet in O(1). Our major contributions are: (a) An enhancement to an existing scheme called windowed coding, whose complexity is greatly reduced and data recovery performance is improved by our proposed approach. (b) A technique that combines elements of windowed coding with a new feedback structure to further reduce the coding complexity and improve data recovery. (c) A coded forwarding scheme in which a relay node provides further resilience against packet loss by overhearing source-to-destination communications and making forwarding decisions based on overheard information.

cs.IT↗

arXiv2021

Coded Relaying in LoRa Sensor Networks

To enhance the reliability of LoRa sensor networks, we propose two opportunistic forwarding protocols in which relays overhear sensor-to-gateway messages and periodically forward them to a gateway. To reduce the number of transmissions, the relays forward XOR sums of the overheard messages. One protocol employs a single relay node, while two relays cooperate in the other. With a single relay, our proposed protocol requires fewer relay transmissions to achieve similar loss rates as conventional uncoded forwarding in which every received message is immediately forwarded. We demonstrate up to 55% reduction in relay transmission time relative to uncoded forwarding. The cooperative protocol provides better loss and delay performance than the single-relay protocol, and we demonstrate up to 16% reduction in the message-loss rate along with 33% reduction in relay transmission times compared to conventional forwarding.

cs.NI↗

arXiv2020

The LoRa Modulation Over Rapidly-Varying Channels: Are the Higher Spreading Factors Necessarily More Robust?

The chirp spread spectrum (CSS) modulation scheme is employed by the physical layer of the Long Range (LoRa) communication technology. In this paper, we examine the performance of CSS over time-varying channels whose gain may change during the reception of a LoRa frame. This is in contrast to the usually employed model in the literature, which assumes the channel gain to be constant throughout a frame. Specifically, we investigate the effects of exponentially correlated Rayleigh fading on the frame-error rate of a CSS receiver in which the channel gain is estimated at the beginning of each frame. Our primary observation is that over rapidly-varying channels, the robustness benefits of the larger spreading factors tend to disappear as the payload size grows. This observation, which is contrary to the common perception that higher spreading factors necessarily provide greater immunity against noise, highlights the need to consider channel characteristics and payload sizes in allocating the spreading factor for reliable and energy-efficient LoRa communications.

eess.SP↗

arXiv2020

Application-Layer Coding with Intermittent Feedback under Delay and Duty-Cycle Constraints

We propose two application-layer coding schemes for delay-constrained point-to-point packet communications with restrictions on the transmitter's maximum duty-cycle. The schemes operate over GF(2) and utilize intermittently available receiver feedback for erasure correction. Applications that will benefit from the proposed schemes include wireless sensor networks in which energy-constrained sensors must deliver readings to a gateway within a deadline. Simulation results for independent Bernoulli erasure channels, Gilbert-Elliott channels, and Long Range (LoRa) communications demonstrate orders-of-magnitude reductions in the delivery failure rate as compared to feedback-assisted repetition redundancy and a blind coding scheme that does not utilize feedback.

cs.NI↗