Power allocation for full-duplex cooperative non-orthogonal multiple access system

Future-generation wireless communication will encounter tremendous mobile data traffic. The main challenging requirements of future networks are increasing the connectivity and achieving higher spectral efficiency compared to previous generations. Non-orthogonal multiple access (NOMA) is an enabling access scheme for future generation wireless technology. It can enhance system performance, increase spectral efficiency and connectivity. However, the weak user suffers poor performance due to the interference and poor channel quality. Full-duplex cooperative NOMA (FD C-NOMA) is an attractive solution to help the weak user by allowing the strong user to relay the weak user signal simultaneously without much degrading the strong user performance. In this thesis, various wireless technologies such as NOMA, cooperative communication, FD, and simultaneous wireless information and power transfer (SWIPT) are investigated to enhance system performance. Different new feasible successive interference cancellation (SIC) techniques are applied to help the weak user to decode its own information. In addition, a power control strategy on the relay power for FD C-NOMA schemes is proposed to reduce the self-interference effect while ensuring an effective link to the weak user. Moreover, the power allocation to improve the system performance is considered for different objective functions such as maximizing the minimum achievable rate (max-min) and the sum-rate. In all considered scenarios, a closed-form solution is derived and compared with Fixed Power Allocation (FPA), Fractional Transmit Power Allocation (FTPA), and half-duplex (HD) C-NOMA. Numerical simulation results show that the max-min power allocation's effectiveness in enhancing the weak user rate performance with considerably better user fairness. The proposed FD C-NOMA system using sum-rate optimization attains better sum-rate performance compared to other schemes and close to the conventional NOMA.