DE-based resource allocation for D2D-assisted NOMA systems

The explosion of wireless network services has led to a need for new technologies and resource allocation schemes. Device-to-device (D2D) can reduce the access pressure of base station (BS) equipment, and non-orthogonal multiple access (NOMA) can multiplex network spectrum resources. The integration of them can further improve the performance of multi-cell networks. However, users still face more interference in multi-cell networks. This paper analyzes the relationship between transmission power and serial interference cancellation decoding order. Aiming at maximizing the sum rate of D2Ds, we propose three feasible frameworks based on the differential evolution (DE) algorithm. First, we invoke a coevolution DE-based resource allocation (CDRA) framework, which encodes the RB assignment and power allocation into the same individual for evolution. Second, we propose an iteration-combining DE-based resource allocation (IDRA) framework, which adopts a two-step DE algorithm to solve optimal power allocation and RB assignment scheme iteratively. Lastly, we invoke the power-repairing DE-based resource allocation (PDRA) framework, which can perform power repair on individuals with failed evolution. Simulation results demonstrate that: (1) the integration of D2D and NOMA techniques is capable of enhancing the achievable sum rate of D2Ds; (2) the three proposed frameworks for multi-cell NOMA networks can effectively optimize the objective function. Compared with CDRA and IDRA, PDRA performs better in terms of convergence speed and maximum D2D rate.