Rohith Reddy Vennam

The future of global connectivity relies on the seamless integration of satellite and terrestrial networks. Recent advancements have enabled terrestrial devices to connect directly to satellites, while high-speed 5G millimeter-wave links offer a promising solution for backhauling ground station data. This paper introduces the concept of joint satellite and terrestrial networks (Jointnets), which necessitates both coexistence and backhaul. In this framework, satellites and ground stations act as relays between terrestrial base stations and devices, removing coverage barriers and providing global connectivity. However, the significant spectrum overlap between 27.5 to 30.0 GHz leads to co-channel interference degrading efficiency or causing complete link failure. Existing approaches only focus on coexistence, resulting in spectrum inefficiency and coverage gaps. We present mmSubArray: Array of Sub-band Phased Arrays, a novel solution utilizing commercial off-the-shelf phased arrays to achieve full-spectrum utilization and enable Jointnets. Through extensive simulations and real-world measurements, we demonstrate the interference challenges and evaluate the efficacy of our approach. Additionally, we have open-sourced our Python simulator and hardware implementation source codes, providing valuable tools for industrial deployment and future research.

We propose a new mmWave radio architecture called delay-phased array (DPA) that improves efficient utilization of large bandwidth and large antenna array at high mmWave frequencies by creating flexible frequency-dependent multi-beams. DPA allows for flexible division of system bandwidth into small bands and independent radiation of each band in different chosen beam directions.

FMCW radars are integral to automotive driving for robust and weather-resistant sensing of surrounding objects. However, these radars are vulnerable to spoofing attacks that can cause sensor malfunction and potentially lead to accidents. Previous attempts at spoofing FMCW radars using an attacker device have not been very effective due to the need for synchronization between the attacker and the victim. We present a novel spoofing mechanism called mmSpoof that does not require synchronization and is resilient to various security features and countermeasures of the victim radar. Our spoofing mechanism uses a “reflect array” based attacker device that reflects the radar signal with appropriate modulation to spoof the victim’s radar. We provide insights and mechanisms to flexibly spoof any distance and velocity on the victim’s radar using a unique frequency shift at the mmSpoof’s reflect array. We design a novel algorithm to estimate this frequency shift without assuming prior information about the victim’s radar. We show the effectiveness of our spoofing using a compact and mobile setup with commercial-off-the-shelf components in realistic automotive driving scenarios with commercial radars.

Modern mmWave systems have limited scalability due to inflexibility in performing frequency multiplexing. All the frequency components in the signal are beamformed to one direction via pencil beams and cannot be streamed to other user directions. We present a new flexible mmWave system called mmFlexible that enables flexible directional frequency multiplexing, where different frequency components of the mmWave signal are beamformed in multiple arbitrary directions with the same pencil beam. Our system makes two key contributions: (1) We propose a novel mmWave front-end architecture called a delay-phased array that uses a variable delay and variable phase element to create the desired frequency-direction response. (2) We propose a novel algorithm called FSDA (Frequency-space to delay-antenna) to estimate delay and phase values for the real-time operation of the delay-phased array. Through evaluations with mmWave channel traces, we show that mmFlexible provides a 60-150% reduction in worst-case latency compared to baselines1.