Research

The cellular phone system represents the most ubiquitous and trusted communication infrastructure in the world. The cellular system has evolved a lot in the past two decades, starting from a basic audio communication system to the current smart phone system. In the last few months, the COVID pandemic has made us realize the cellular network's enormous importance more, and it has become the most integral part of human life. As the whole nation is looking forward to the jump from 4G to 5G LTE network, we look for the brighter side of 100x faster download speed, 10x decrease in latency, and 100x increase in network capacity. However, with all these advantages comes a greater risk of privacy of the users. The Cybersecurity & Infrastructure Agency (CISA) director Christopher Krebs stated in the August 2020 report “From my perspective, 5G is the single biggest critical infrastructure build that the globe has seen in the last 25 years and, coupled with the growth of cloud computing, automation, and future of artificial intelligence, demands focused attention today to secure tomorrow.” To achieve higher bandwidth and broader coverage, the 5G loosen the network architecture's tight control, which opens several vulnerabilities.

Open and dynamic spectrum access model brings forth a serious challenge of sustenance among the CRN and makes them more susceptible to jamming-based denial of service (DoS) attacks. Inspired by honeypot in the network security, we propose a honeynet based defense mechanism called CR-honeynet. CR-honeynet aims to avoid attacks on legitimate communications by dedicating a Secondary User (SU) as a honeynode, to deter the attacker from attacking legitimate SUs and attack the honeynode instead.

Directional Radio Frequency (RF) / Free-Space Optical (FSO) transceivers have the potential to play a significant role in future generation wireless networks. They are advantageous in terms of improved spectrum utilization, higher data transfer rate, and lower probability of interception from unwanted sources. Despite these advantages, communications using directional transceivers require establishment and maintenance of line-of-sight (LOS). Thus, the establishment of the communication link or neighbor discovery plays a significant role in mobile ad hoc networks with RF/FSO directional transceivers. In this project, we design protocols for discovering LOS of a neighbor for both in-band and out-of-band cases.

In multihop ad hoc networks, a jammer can drastically disrupt the flow of information by intentionally interfering with links between a subset of nodes. The impact of such attacks can escalate when the jammer is moving. As a countermeasure for such attacks, adaptive beam-forming techniques can be employed for spatial filtering of the jamming signal. This paper investigates the performance of adaptive beam nulling as a mitigation technique against jamming attacks in multihop ad hoc networks. Considering a moving jammer, a distributed beam nulling framework is proposed.

Rampant dynamic spectrum allocation over time leads to the creation of narrow spectrum holes which can be aggregated to fulfill the bandwidth requirements of users. Even though this approach increases the throughput, it comes at the cost of degraded spectrum utilization due to a rise in the number of required guard bands. This project aims at how a transmitter- receiver pair can coordinate among themselves on choosing the correct frequency and bandwidth for actual data communication. The next objective is to optimize the spectrum usage of each transmission such that the nodes can dynamically adapt to the environment and enhance resource utilization.

UAV networks are envisioned to play a crucial role in the future generations of wireless networks. Due to the high cost of failures in system-based tests, initial analysis and refinement of designs and algorithms for UAV applications are performed through rigorous simulations. To facilitate such simulations for UAV systems, we presents different mobility models for emulation of a UAV's movement. We further extend these models by considering the effect of large obstacles on movement patterns following the three models. The mobility models are prepared as open-source add-ons for ns-3 network simulator.

In WiMAX deployment, the challenges to service providers lie with the Quality of Service (QoS) under varying fading environment while at the same time maximizing for resource utilization. In this research, a rigorous and comprehensive performance study of mobile WiMAX has been made with respect to adaptive modulation and coding techniques considering the variation in the speed of the mobile, path-loss, scheduling services and application type for comparing with the fixed type of modulations.