This correspondence considers non-orthogonal multiple access (NOMA) assisted mobile edge computing (MEC), where the power and time allocation is jointly optimized to reduce the energy consumption of computation offloading. Closed-form expressions for the optimal power and time allocation solutions are obtained and used to establish the conditions for determining whether the conventional orthogonal multiple access (OMA), pure NOMA or hybrid NOMA should be used for MEC offloading. Index Terms-Non-orthogonal multiple access (NOMA), mobile edge computing (MEC), and MEC offloading. Both non-orthogonal multiple access (NOMA) and mobile edge computing (MEC) have been recognized as important techniques in future wireless networks [1], [2] . Sophisticated optimization frameworks developed in [3] , [4] show that by applying NOMA to MEC, not only can severe delay be avoided, but also energy consumption can be reduced, although the comparisons between NOMA and orthogonal multiple access (OMA) in [3], [4] rely on simulation. Insightful analytical results developed in [5] confirmed the advantages of NOMA-MEC offloading, by using fixed bandwidth allocation. This correspondence studies the impact of NOMA on energyefficient MEC offloading, by focusing on the fundamental twoscheduled-user case in order to obtain an insightful understanding of NOMA-MEC. The existing studies in [3]-[5] consider two offloading strategies only, namely OMA and pure NOMA (i.e., the users are served simultaneously and no one is given extra time). In this paper, we propose a third strategy, termed hybrid NOMA, in which a user first offloads parts of its task by using a time slot allocated to another user and then offloads the remainder of its task during a time slot solely occupied by itself. The performance of the three strategies is studied in this paper, where closed-form expressions for the optimal time and power allocation solutions are obtained, by applying geometric programming (GP). These closed-form solutions not only facilitate low-complexity Manuscript
A non-orthogonal multiple access (NOMA) enabled MEC was studied in REF , and the time allocation and power were optimized in combination to reduce the energy cost of computing offload.
Joint Power and Time Allocation for NOMA–MEC Offloading
IEEE Transactions on Vehicular Technology
IEEE Transactions on Vehicular Technology
Mathematics Computer Science