My research centers on the modeling of wireless communication systems. I use mathematical tools to model, analyze, optimize, and design new wireless communication architectures. These models are then simulated in a computer environment to validate the theoretical results. A key focus of my work is on the core technologies that will drive future 6G wireless networks.

Currently, I am working on mixed communication models aimed at enabling long-distance, high-capacity transmission for next-generation 6G wireless communication networks. These models integrate multiple communication technologies such as Radio Frequency (RF), Free-Space Optics (FSO), Terahertz (THz), and Underwater Optical Wireless Communication (UOWC) to utilize their respective advantages and ensure reliable connectivity across heterogeneous environments.

A key enhancement in our architecture is the use of Reconfigurable Intelligent Surfaces (RIS), which play a vital role in shaping the wireless propagation environment. RIS consists of a large number of passive, low-cost reflective elements that can be dynamically programmed to control the phase, amplitude, and direction of incident electromagnetic waves. By intelligently reflecting signals toward desired directions, RIS helps to overcome challenges such as path loss, blockage, and fading, especially in complex or harsh environments. In our mixed model, RIS enables more efficient signal routing, improved link quality, and enhanced secrecy and spectral efficiency, making it a promising enabler for energy-efficient and highly reliable 6G communication systems.

Ongoing Projects

Terahertz Communication

As part of my ongoing research on 6G wireless networks, I am currently working on Terahertz (THz) communication—a next-generation wireless technology that holds immense promise for massive-capacity data transmission. This project primarily focuses on developing accurate channel models for THz links by analyzing critical propagation impairments such as severe path loss, pointing errors, and high sensitivity to atmospheric conditions. Given the extremely short wavelength of THz signals, they are particularly vulnerable to blockage, scattering, and alignment issues. To address these, I am evaluating the performance of THz channels under diverse deployment scenarios, including urban, suburban, and rural environments, to better understand how environmental complexity affects signal reliability, coverage, and data integrity. A core component of this research is the integration of RIS, which serve as passive, programmable reflectors capable of intelligently controlling the propagation of THz signals. By dynamically shaping the wireless environment, RIS can redirect beams, bypass obstacles, and maintain line-of-sight conditions, significantly enhancing signal strength, coverage range, and resilience in harsh environments.

Moreover, I analyze the secrecy performance of THz communication systems, assessing their vulnerability to eavesdropping threats, which is vital for ensuring secure transmission in 6G networks. The insights from this study will contribute to the design of intelligent, secure, and high-throughput wireless systems, playing a pivotal role in realizing the vision of next-generation 6G networks for applications such as holographic communication, wireless virtual reality, and autonomous systems.

Recent Publication: Md. Abdur Rakib, Md. Ibrahim, A. S. M. Badrudduza, Imran Shafique Ansari, Sumit Chakravarty, Imtiaz Ahmed and S. M. Abdur Razzak, "An RIS-Empowered THz-UWO Relay System for Air-to-Underwater Mixed Network: Performance Analysis With Pointing Errors," in IEEE Internet of Things Journal, vol. 11, no. 10, pp. 17097-17112, May 2024.

FSO Communication

Free-Space Optics (FSO) Communication stands out as a key enabler for 6G wireless networks, offering ultra-high data rates, low latency, and unlicensed spectrum utilization, making it ideal for high-capacity, short- to medium-range links. As 6G expands into the aerial domain, Unmanned Aerial Vehicles (UAVs) are increasingly being deployed as agile communication platforms for surveillance, disaster response, and data relaying. Importantly, the project also explores the deployment of FSO links in UAV-based communication systems, analyzing how RIS can support reliable air-to-ground and air-to-air links. This research will provide critical insights into the optimal positioning of UAVs, ensuring stable and efficient FSO connectivity even in challenging environments.

In this research, I focus on comprehensive channel modeling of FSO systems by investigating real-world impairments such as atmospheric turbulence, pointing errors, and the line-of-sight (LoS) dependency that inherently limits FSO performance in dynamic or obstructed environments. To overcome these challenges, the project introduces the integration of RISs to dynamically redirect and enhance optical signal propagation. The study includes optimization of RIS parameters, such as the number and placement of RIS units, and the fine-tuning of reflecting elements, to improve coverage, link quality, and adaptability. The study also involves the performance assessment of various modulation techniques (e.g., QAM, QPSK) and detection schemes at the receiver under different channel conditions.

Recent Publication: Md. Abdur Rakib, Md. Ibrahim, A. S. M. Badrudduza, Imran Shafique Ansari, and Heejung Yu, "RIS-Aided Free-Space Optics Communications in A2G Networks over Inverted Gamma-Gamma Turbulent Channels," in ICT Express, in press.

Underwater Communication

Underwater Optical (UWO) Communication is gaining attention as a critical enabler for extending 6G wireless networks into the underwater domain, where high-speed, low-latency links are essential for applications such as ocean exploration, underwater sensor networks, naval operations, and offshore infrastructure monitoring. However, the performance of UWO systems is severely impacted by environmental impairments such as air bubble density, temperature gradients, and pointing errors, all of which degrade signal strength and alignment. Additionally, the optical signal behaves differently in salty (oceanic) versus freshwater environments—oceanic waters, with higher scintillation indices, exhibit stronger turbulence and greater signal fading. In practice, direct line-of-sight (LOS) communication is often impossible due to obstacles like seamounts, sediment layers, underwater infrastructures, naval mines, and other natural or artificial blockages.

One of the key challenges in underwater wireless communication is the reliable transmission of information from the surface to submerged platforms, such as submarines, over long distances. Traditional underwater acoustic communication has been widely used for this purpose; however, it suffers from significant drawbacks including very low data rates, high latency, and severe signal attenuation in deep water. To overcome these limitations, a promising alternative is the use of a mixed Radio Frequency–Underwater Optical Communication (RF-UWOC) system. In this mixed approach, the RF signal is employed for the above-water (surface) link, offering robust connectivity over longer distances through air, while the optical signal is used for underwater communication, enabling high-speed and low-latency data transmission in clear water conditions. Moreover, a comparative analysis with traditional acoustic models is also included to demonstrate the advantages of UWO systems in terms of speed, data integrity, and energy efficiency.

Recent Publication: Abrar Bin Sarawar, A. S. M. Badrudduza, Md. Ibrahim, Imran Shafique Ansari, and Heejung Yu, "Secrecy Performance Analysis of Integrated RF-UWOC IoT Networks Enabled by UAV and Underwater-RIS," in IEEE Internet of Things Journal, in press.

RF Communication

Radio Frequency (RF) communication continues to play a foundational role in the development of next-generation wireless networks, despite the emergence of advanced technologies like THz, optical, and quantum communication. RF offers reliable, wide-area coverage, robust performance in non-line-of-sight (NLoS) conditions, and strong penetration through obstacles.

Security remains a critical challenge in RF communication due to its inherently broadcasting nature, which makes it highly vulnerable to eavesdropping attacks. In the context of 6G wireless networks, physical layer security (PLS) has gained considerable attention as a means to provide lightweight, scalable protection without relying solely on upper-layer encryption. One of the major concerns is that the secrecy performance can degrade significantly as the number of eavesdroppers increases, leading to higher risks of information leakage. To address this, antenna diversity emerges as a powerful tool, with Multiple-Input Multiple-Output (MIMO) systems playing a pivotal role. MIMO not only improves link capacity but also enhances security by enabling techniques like beamforming and artificial noise injection. However, MIMO systems can introduce channel correlation and interference, especially in dense environments. This issue can be effectively mitigated by deploying Reconfigurable Intelligent Surfaces (RIS) between the transmitter and receiver, which help in optimizing the channel conditions. Additionally, the integration of opportunistic relaying techniques, where only the most secure and reliable relay is selected dynamically, can further increase secrecy by introducing path diversity and signal obfuscation across multiple hops.

Recent Publication: Md. Roisul Ajom Ruku, Md. Ibrahim, A. S. M. Badrudduza, Imran Shafique Ansari, Waqus Khalid and H. Yu, "Effects of co-channel interference on RIS empowered wireless networks amid multiple eavesdropping attempts," in ICT Express, vol. 10, no. 3, pp. 491-497, Jun. 2024.

Thesis Coordination

13. Al Nahian Mugdho (Roll 1804021), "Enhancing Terrestrial Mobile Backhaul Networks: Performance Analysis of Hybrid FSO/THz Relay Communication Integrated with Aerial RIS".

12. Aridra Chandra Jhalok (Roll 1804055), "Enhancing Downlink NOMA Communication: Performance Insights of FSO-RF Hybrid Systems with RIS and STAR-RIS Integration".

11. Syed Mumit Baksh (Roll 1704046), "Design and Analysis of Direct and Reconfigurable Intelligent Surface assisted Underwater Wireless Optical Communication System".

10. Miadul Islam Mitul (Roll 1704037), "RIS-Empowered Cognitive Radio based RF/UWOC Hybrid Communications: Channel Modeling and Secrecy Performance Analysis".

9. Md. Abdur Rakib (Roll 1701049), "A RIS Empowered THz-UWO Relay System for Air-to-Underwater Mixed Network: Performance Analysis with Pointing Errors".

8. Md. Fahim (Roll 1804058), "Enhancing Security Measures in RF-FSO Connectivity: Wireless Jamming with Save-Transmit Protocol Integration".

7. Abrar Bin Sarawar (Roll 1704005), "Secrecy Performance Evaluation of RIS Assisted UAV Communication over Hybrid RF-UWOC Network".

6. Mst. Muktara Khatun (Roll 1704022), "Secure Outage Performance Analysis of RIS Aided Wireless Communication over FSO/PLC Mixed System".

5. Anika Tabassum Biva (Roll 1704056), "Multiple RIS-aided Mixed RF/FSO Wireless Network: A Secrecy Tradeoff".

4. Md. Mijanur Rahman (Roll 1604004), "Impact of Simultaneous Eavesdropping via RF and FSO Links over RIS-aided RF and FSO Mixed Networks".

3. Tahmid Ibne Ahmed (Roll 1604005), "Effective Secrecy Throughput Analysis of RIS-assisted Dual-hop RF-FSO Variable Gain Relaying Channel".

2. Rabbi Al Noman (Roll 1604052), "Secrecy Performance Analysis of a Cognitive RF-UWOC System under Collusion and Non-collusion of Multiple Eavesdroppers".

1. Md Shakhawat Hossen (Roll 144039), "On The Physical Layer Security of Mixed Radio Frequency-Underwater Optical Wireless Communication Network".

Thesis Book

Secure Wireless Multicasting Through Composite K and KG Distribution Channels with Opportunistic Relying by Md. Ibrahim; M.Sc. Engineering