Browsing by Author "Hemachandra, KT"

Now showing 1 - 3 of 3

item: Article-Full-text
Device-free user authentication, activity classification and tracking using passive WI-fi sensing: a deep learning-based approach
(IEE, 2020) Jayasundara, V; Jayasekara, H; Samarasinghe, T; Hemachandra, KT
Growing concerns over privacy invasion due to video camera based monitoring systems have made way to non-invasive Wi-Fi signal sensing based alternatives. This paper introduces a novel end-to-end deep learning framework that utilizes the changes in orthogonal frequency division multiplexing (OFDM) sub-carrier amplitude information to simultaneously predict the identity, activity and the trajectory of a user and create a user profile that is of similar utility to a one made through a video camera based approach. The novelty of the proposed solution is that the system is fully autonomous and requires zero user intervention unlike systems that require user originated initialization, or a user held transmitting device to facilitate the prediction. Experimental results demonstrate over 95% accuracy for user identification and activity recognition, while the user localization results exhibit a ±12cm error, which is a significant improvement over the existing user tracking methods that utilize passive Wi-Fi signals.
item: Conference-Full-text
Performance evaluation of uav-assisted millimeter wave noma networks
(IEEE, 2022-07) Sarathchandra, TN; Hemachandra, KT; Kusaladharma, S; Rathnayake, M; Adhikariwatte, V; Hemachandra, K
Mobile users may experience frequent service outages or poor quality of service in rural areas due to the scarcity of base stations in the proximity. Therefore, a cost effective and flexible solution is introduced in this paper with unmanned aerial vehicles (UAVs) and terrestrial base stations (TBSs), coexisting under a stochastic network with the combination of millimeter waves and non-orthogonal access (NOMA) techniques. This is achieved by deploying both the UAVs (millimeter wave frequencies) and TBSs (sub-6 GHz frequencies) in the same system, and selecting the transmitter based on a user association scheme. The maximum signal-to-interference-plus-noise ratio (SINR) and the closest transmitter user association schemes are compared using extensive simulations to identify the most suitable scheme in terms of the outage probability and the achievable downlink rate. The results show that the closest transmitter user association policy results in lower outage probability and higher downlink rates for UAV-assisted millimeter wave NOMA Networks.
item: Article-Full-text
Physical layer security for intelligent reflecting surface assisted two-way communications
(IEEE, 2021) Wijewardena, M; Samarasinghe, T; Hemachandra, KT; Atapattu, S; Evans, JS
This letter investigates the exploitation of an intelligent reflecting surface (IRS) to communicate securely in a two-way network consisting of an untrusted user. In particular, the transmit powers and the phase shift at each element of the IRS are optimized to maximize the sum-secrecy rate, such that the IRS-reflected and non-IRS-reflected signals are added destructively at the untrusted user. The proposed iterative algorithm converges rapidly to a feasible solution of high accuracy with a few iterations. Numerical results demonstrate sum-secrecy rate gains up to 120% compared to naive or partially optimized schemes.