Exploiting Cooperative Downlink NOMA in D2D Communications.

Area of Science:

• Wireless Communication
• Telecommunications Engineering
• Information Theory

Background:

• Device-to-device (D2D) communication offers direct node interaction.
• Non-orthogonal multiple access (NOMA) enhances spectral efficiency.
• Cooperative communication improves reliability and coverage.

Purpose of the Study:

• To propose and investigate a novel Bidirectional Cooperative Downlink Non-Orthogonal Multiple Access (BCD-NOMA) scheme.
• To enhance performance metrics such as outage probability (OP), ergodic capacity (EC), and energy efficiency.
• To enable simultaneous bidirectional D2D messaging alongside cooperative data transmission.

Main Methods:

• Developing a BCD-NOMA transmission scheme utilizing a shared relay node.
• Deriving analytical expressions for OP, EC, and ergodic sum capacity (ESC).
• Conducting simulations under both perfect and imperfect successive interference cancellation (SIC) conditions.

Main Results:

• BCD-NOMA demonstrates improved outage probability compared to conventional schemes.
• The scheme achieves high ergodic capacity and energy efficiency.
• Effectiveness is validated through analytical and simulation results for various SIC scenarios.

Conclusions:

• BCD-NOMA effectively enhances wireless communication performance.
• The proposed scheme offers a viable solution for efficient bidirectional D2D and cooperative NOMA systems.
• The findings highlight the benefits of integrating cooperative NOMA with bidirectional D2D communication.