TNThe-Anh Ngo

The-Anh Ngo

University of Transport and Communications
*This is an algorithmically generated author record based on publicly available information.
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The-Anh Ngo has a total of 11 co-authors. Here are the top co-authors by number of shared publications:

Latest Publications

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    Exact outage and intercept analysis of physical layer security in half-duplex energy harvesting relay systems

    by The-Anh Ngo, Xuan-Truong Tran, Viet-Thanh Le, Thien P. Nguyen, Duy-Hung Ha

    This paper investigates physical layer security (PLS) in a half duplex (HD) relay network with radio frequency energy harvesting (EH). We consider an amplify and forward (AF) protocol in which both the source and the relay harvest energy from a dedicated power beacon, while a passive eavesdropper attempts to intercept the confidential message. Unlike prior studies that rely on asymptotic analysis or numerical integration, we derive exact closed form expressions for the outage probability (OP) and the intercept probability (IP). The proposed expressions characterize the reliability and secrecy trade-off in energy limited cooperative relaying and enable efficient performance evaluation. Monte Carlo simulations validate the analysis and match the theoretical results. Moreover, the closed form results reveal how channel conditions and harvesting duration jointly shape outage and interception behaviors. We further quantify the impacts of normalized transmit power, the time allocation factor between harvesting and information transmission, and the EH efficiency. The results provide practical guidance for selecting system parameters to meet target reliability and secrecy levels, and they show that the time allocation factor must be carefully chosen to balance harvested energy and transmission time.

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    Half-duplex Two-way Relaying for Wireless Sensor Networks with Adaptive Coding Rate: A Performance Optimization Framework

    by The-Anh Ngo, Viet-Thanh Le, Thien P. Nguyen, Duy-Hung Ha

    In this paper, a novel framework to enhance the reliability of wireless sensor networks (WSNs) by addressing the high probability of outage (OP) resulting from limited energy resources and unreliable channels. The framework integrates three techniques: half-duplex two-way relaying (HD-TWR), digital network coding (DNC), and rateless codes. Although these techniques have been extensively studied in isolation, a comprehensive analysis of their joint performance is provided as the main contribution. The proposed scheme leverages the energy efficiency of HD-TWR, the transmission reduction capability of DNC, and the retransmission-free resilience of rateless codes. Simulation results show that the integrated framework significantly reduces OP, offering a robust and practical solution to enhance the reliability enhancement. Furthermore, the impact of optimal relay node placement is investigated through parameter adjustments in the simulation stage to maximize performance gains.

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    Evaluating the Reliability and Security of an Uplink NOMA Relay System Under Hardware Impairments

    by Duy-Hung Ha, The-Anh Ngo, Xuan-Truong Tran, Minh-Linh Dam, Viet-Thanh Le, Agbotiname Lucky Imoize, Chun-Ta Li

    With the rapid growth of wireless devices, security has become a key research concern in beyond-5G (B5G) and sixth-generation (6G) networks. Non-orthogonal multiple access (NOMA), one of the supporting technologies, is a strong contender to enable massive connectivity, increase spectrum efficiency, and guarantee high-quality access for a sizable user base. Furthermore, the scientific community has recently paid close attention to the effects of hardware impairments (HIs). The safe transmission of NOMA in a two-user uplink relay network is examined in this paper, taking into account both hardware limitations and the existence of listening devices. Each time frame in a mobile network environment comprises two phases in which users use a relay (R) to interact with the base station (BS). The research focuses on scenarios where a malicious device attempts to intercept the uplink signals transmitted by users through the R. Using important performance and security metrics, such as connection outage probability (COP), secrecy outage probability (SOP), and intercept probability (IP), system behavior is evaluated. To assess the system’s security and reliability under the proposed framework, closed-form analytical expressions are derived for SOP, IP, and COP. The simulation results provide the following insights: (i) they validate the accuracy of the derived analytical expressions; (ii) the study significantly deepens the understanding of secure NOMA uplink transmission under the influence of HIs across all the network entities, paving the way for future practical implementations; and (iii) the results highlight the superior performance of secure and reliable NOMA uplink systems compared to benchmark orthogonal multiple access (OMA) counterparts when both operate under the same HI conditions. Furthermore, an extended model without a relay is considered for comparison with the proposed relay-assisted scheme. Moreover, the numerical results indicate that the proposed communication model achieves over 90% reliability (with a COP below 0.1) and provides approximately a 30% improvement in SOP compared to conventional OMA-based systems under the same HI conditions.

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    Cải thiện hoạt động của các trạm chuyển tiếp để duy trì kết nối cho các cuộc gọi chuyển giao trong hệ thống 4G LTE bằng kỹ thuật chuyển tiếp kênh

    by Anh Ngô Thế, Tân Trần Huỳnh Minh, Trang Phạm Huyền, Thạch Lê Ngọc

    Thông thường, các trạm chuyển tiếp RS (Relay Station) được sử dụng trong các hệ thống 4G LTE với mục đích mở rộng vùng phục vụ hoặc cải thiện chất lượng phủ sóng cho một vùng của một trạm gốc BS (Base Station) nào đó thông qua việc chuyển tiếp các thông tin giữa trạm gốc BS tới một người sử dụng di động MU (Mobile User) cụ thể. Điều này làm cho việc sử dụng tài nguyên tần số vô tuyến được cấp phát cho các BS chưa thực sự tối ưu. Ngoài ra, việc duy trì kết nối cho các cuộc gọi chuyển giao trong các hệ thống thông tin di động vẫn luôn là một thách thức với cả các nhà nghiên cứu và các nhà cung cấp dịch vụ di động. Việc sử dụng các RS để nâng cao tỉ lệ thành công cho các cuộc gọi chuyển giao cũng như tận dụng hiệu quả tài nguyên tần số là một đề tài hấp dẫn cho các nhà nghiên cứu. Trong bài báo này, các RS được sử dụng không những để mở rộng vùng phủ của các BS mà còn giúp cho BS khai thác tối đa dung lượng cho các cuộc gọi mới mà vẫn đáp ứng được yêu cầu phục vụ của các cuộc gọi chuyển giao, kể cả với các MU sử dụng dịch vụ dữ liệu (data) thời gian thực. Hơn nữa, việc sử dụng các RS đã giúp cho các nhà khai thác mạng có thêm một góc nhìn về việc cấp phát dung lượng hợp lý cho các BS nhằm tối ưu hóa bài toán sử dụng tần số trong hệ thống. Các kết quả mô phỏng chỉ ra rằng khi các BS được cấp 30 kênh tần số, việc sử dụng RS cho phép bảo đảm xác suất chuyển giao thành công trên 99,9%.