A Delay-aware NOMA-aided Mobile Edge Computing Scheme Via User Cooperation

The revolution of smart terminals has directly promoted the revolution of new mobile applications,and the demand for new mobile applications has rapid growth of data volume and speed.The requirements for rapid development of new high-bandwidth and low-latency applications about quality of experience(QoE)and quality of service(QoS)continue to increase.MEC technology can meet high latency requirements.So the advantage of reducing user's local computing energy consumption is a current research hotspot.Non-orthogonal multiple access(NOMA),as a multiple access technology that meets the needs of large-scale connections,improves spectrum efficiency by reusing frequency domains or code domains is a 5G network design wireless access technology basic principles.We propose a NOMA aided cooperative computing scheme in a basic three-node MEC.The collaboration research about NOMA and MEC continue to be updated,but the latest MEC research has not yet explored all the potential benefits of NOMA in the context of MEC.Most of the existing articles consider using NOMA to increase the number of users' access and offload multi-user task,but they do not consider the different delay performance of users.So we study a delay minimization problem by joint communication and computation resource allocation of the user and helper.(1)Taking into account the different time delay requirements of different tasks of users,a joint offloading scheme is proposed to helper assist in computing.Under the premise that the users are half-duplex,the user use NOMA offload tasks to the helper and the MEC server.By sharing computing resources to reduce task completion time,the helper will not compute its own tasks in the next time slots,the NOMA-MEC system makes full use of the computing resources of the helper and the advantages of D2 D links,and effectively utilizes idle spectrum resources,the spectrum efficiency has been significantly improved.(2)While ensuring the quality of service and delay requirements of the user who is first offloaded,this solution also allocates the user's tasks split ratio and NOMA power allocation,taking the delay of helper as the objective function,and optimization problem is non-convex problems,this paper uses the SPCA method to transform the non-convex constraints in the model into upper bound convex constraints,and solve the converted convex optimization problem.The MATLAB simulation of this scheme is carried out,and the simulation results show that the NOMA offloading scheme that the helper assist in the calculation has the advantage of reducing the time delay of the helper and the energy consumption of the user.(3)On the basis of the existing scheme,this paper proposes a new improvement scheme to improve the delay performance of the user.By increasing the delay constraint factor,and simulated the unloading scheme with the original delay of 90% and 95% of the unloading user.,and the simulation results illustrate the superiority of the new unloading scheme.