Browsing by Author "Hassan, Sumeyra"

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Citation - Scopus: 1
Design of Secure Multi-User Coded-SSK With Index Selecting Capability
(IEEE-Inst Electrical Electronics Engineers Inc, 2025) Hassan, Sumeyra; Panayirci, Erdal; Helleseth, Tor; Poor, H. Vincent
We propose a new coded space shift keying (CSSK) signaling technique for multi-user (MU), multiple-input multiple-output (MIMO) communication systems incorporating physical layer security (PLS). Besides its error correction ability, the designed linear code is capable of choosing transmit antenna indices automatically and selecting the best set of antenna combinations that minimizes the bit error rate (BER). Results obtained for the single-user (SU) schemes are then extended to a general single-cell downlink MU CSSK setting. A precoder design is proposed with a maximum ratio combining (MRC) technique to eliminate the multi-user interference (MUI) entirely by taking advantage of channel state information (CSI) at the transmitter. It is shown that the same precoding provides a very effective jamming signal for the PLS against passive eavesdroppers, degrading their signal-to-interference-plus-noise ratio (SINR) severely. A closed-form expression for the achievable secrecy rates is derived and it is maximized by the proposed power allocation algorithm. Finally, it is shown analytically and by computer simulations that substantially better BER performance is achieved by each user over interference-free transmission compared to an SU transmission with a maximum likelihood (ML) detector.
Citation - WoS: 1
Citation - Scopus: 1
Physical Layer Security With Mimo-Generalized Space Shift Keying Modulation Technique in Li-Fi Systems
(Ieee, 2024) Hassan, Sumeyra; Panayirci, Erdal
In this study, a physical layer security algorithm based on generalized space shift keying modulation for visible light communication systems has been developed. Initially, the algorithm selects the most suitable index combinations for ideally activating the photodiodes in the receiver through a designed linear encoder, thereby enhancing error correction capabilities. Subsequently, a customized precoding matrix is developed using this index information and the channel state information to provide an optimum bit error rate for the legitimate receiver, Bob. This approach also degrades the bit error performance of the illegitimate receiver, Eve, thus ensuring high-level security at the physical layer in Li-Fi systems. Experiments conducted with Monte-Carlo simulations demonstrate the effectiveness of this methodology for scenarios requiring secure communication.
Secure Optical Coded GSSK System with Dimming
(IEEE, 2024) Hassan, Sumeyra; Panayirci, Erdal; Helleseth, Tor; Poor, H. Vincent
In this work, we develop an indoor visible light communications (VLC) system based on a transmitted precoded (TPC)-aided, coded generalized space shift keying (GSSK) system with physical layer security (PLS) capability in the presence of dimming. A new design of the encoder and decoder of linear codes is given to improve the error-correcting capability of the system as well as to enable random selection of the activated indices in the GSSK automatically. The PLS of the system is guaranteed by the appropriate selection of the power allocation coefficients for randomly activated photodiodes (PDs). At the receiver, the unknown channel and dimming coefficients are jointly estimated in the legitimate users with a new pilot-aided estimation technique. Then, the optimal detection of the spatial symbols is implemented using the maximum likelihood (ML) criterion in the presence of dimming. It is shown that the dimming coefficients, unknown to the eavesdropper, provide additional PLS for the legitimate user. The computer simulations show that the legitimate user achieves excellent bit error performance mainly due to the linear coding employed that serves for error correction and selection of the best GSSK constellation in the system. In contrast, the bit error performance of the potential eavesdroppers is significantly degraded.