Research Projects

Terahertz (THz) and optical wireless communications technologies are envisioned as potential candidates to successfully realise the potential of communication networks beyond fifth-generation or even sixth-generation. These emerging technologies provide higher bandwidth, higher confidentiality, and stronger anti-interference ability. Compared to mm-wave and optical-based communication systems, the THz-based communication systems exhibit resilience towards atmospheric effects. This characteristic facilitates simplified beamforming, enabling the subsequent deployment of the THz-based communication systems in environments with high QoS requirements. Nevertheless, severe attenuation due to molecular absorption limits the use of the THz spectrum in underwater communications. Recently, underwater wireless optical communication (UWOC) technology has achieved higher data rates and lower link delay. UWOC systems provide efficient transmission solutions for various underwater applications such as target identification, coordinates of the placement of underwater mines, weapon system parameters, offshore oil field exploration, oceanographic data collection, and port security. Although both the THz and UWOC links are inherently invulnerable to eavesdropping due to the utilization of the highly directive beams, the presence of a malicious node inside the beam pattern of the UWOC link results in confidential information leakage. Therefore, in a mixed THz-UWOC system, the prime objective is to maintain confidentiality when confidential information is related to military and defense purposes. To maintain confidentiality and reliability in information transmission, physical layer security (PLS) techniques are employed. Based on the characteristic features of the wireless channel, the PLS techniques are practically independent of the limited computational power assumption of the malicious node. The proposed research project aims to establish and develop a secure mixed THz/UWOC-based communication system for naval applications. By quantifying the role of an eavesdropper in the underwater scenario from a partial secrecy regime. Under a partial secrecy regime, secure transmission is based on the equivocation concept, which represents Eve's confusion level and provides information on the amount of information leakage towards Eve. A mixed TH-UWOC system is considered for the information transmission between Source (S), Relay (R), Destination D and Eavesdropper (E). Under this communication scenario, various secrecy performance metrics such as generalized secrecy outage, average fractional equivocation and average information leakage rate are utilized to articulate Eve's effect. The proposal will address the impact of small- and large-scale fading on the system's secrecy. The proposal will cater for the amount and rate of confidential information leakage. Finally, the contribution of antenna misalignment and hardware impairments on the information-theoretic security.