Research Of Resource Allocation In NOMA-Cooperative Network Based On SWIPT

With the rapid process in modern wireless communication technology,the contradiction between the user's high data rate,high quality of service demand and the shortage of spectrum resources are increasingly prominent.NOMA-cooperative network which combines Non-Orthogonal Multiple Access(NOMA)and cognitive radio network can significantly improve spectrum efficiency.In NOMA-cooperative network,the secondary user assists the primary user transmission as a relay and transmit its own information in the band of the primary user at the same time.When nodes are energy constrained nodes,such as Device-to-Device(D2D)or sensor node,the secondary users need to consume their energy to take part in cooperative,so that energy constrained problem is more serious.Therefore,how to continue providing energy is a hot issue of the NOMA-cooperative network.Meanwhile,to use the very limited wireless resource effectively and increase the transmission rate of the network,it is very necessary to study the NOMA-cooperative network based on SWIPT.In this thesis,we mainly study resource allocation in NOMA-cooperative network based on SWIPT.First,bring energy-harvesting into the NOMA-cooperative network.Secondly,study resource allocation in NOMA-cooperative network based on SWIPT.The performance of this system is improved by optimizing the power factor of the secondary user.In this model,there exist energy-harvesting process and cooperative process,the first time-slot is energy-harvesting process which the slot time decides how much energy is collected,the second time-slot is the cooperative process which the amount of energy decides quality of cooperative,the quality of the cooperative process directly affects the transmission rate of cognitive users.In this model,how to reasonably allocate the energy-harvesting slot and cooperative slot in unit transmission time is a significant problem.To solve the above problems,this thesis considers the characteristic of energy-harvesting process and cooperative process,modeling the capacity maximization problem.The optimization goal is maximizing the transmission rate,time-slot factor and power factor in the secondary user receiver as the optimization variables,the maximization problem is about two variables.Use two-step method to reduce complexity,so that the problem is simplified as one element optimization problem associated with the transmission slot.Finally,design optimal adaptive time-slot optimization algorithm to solve optimization problem.But the complexity of this algorithm is high,to further improve the algorithm efficiency,a heuristic adaptive time-slot optimization algorithm is proposed.The simulation results show that compared with the traditional cognitive radio network,this network has a significant advantage in the transmission rate and efficiency,a heuristic adaptive time-slot optimization algorithm converges faster and has lower complexity.