Abstract
In this paper, a non-orthogonal multiple access (NOMA)-based mobile edge computing (MEC) system is proposed, where paired users (the mth user and the nth user) offload tasks to the MEC server under imperfect channel state information (ipCSI) condition. To evaluate the effect on performance under ipCSI condition in NOMA-MEC system, this study derives new exact and asymptotic expressions of the offloading outage probability for two users under ipCSI and perfect channel state information (pCSI) conditions. On the basis of the theoretical derivation, the diversity orders of the nth user under ipCSI and pCSI conditions are zero and n, respectively, while those for the distant user are all zeros. In addition, we also investigate the system throughput and energy efficiency of NOMA-MEC in delay-limited transmission. Numerical results show that (1) the offloading outage behaviors of NOMA-MEC are better than those of time division multiple address (TDMA), (2) the offloading outage performance of paired users under ipCSI is worse than that under pCSI, and (3) the NOMA-MEC system achieves higher throughput and energy efficiency than does the TDMA-MEC system.
Highlights
Future wireless communication will face the challenges of network requirements, such as high-density users, high speed, and ultra-reliable and low latency communications (URLLC)
2) We evaluate theoretical results of system performance by simulation, which shows that the offloading outage probability under imperfect channel state information (ipCSI) is larger than that under perfect channel state information (pCSI)
We find that Non-orthogonal multiple access (NOMA)-mobile edge computing (MEC) has higher system throughput and energy efficiency than time division multiple address (TDMA)-MEC
Summary
Future wireless communication will face the challenges of network requirements, such as high-density users, high speed, and ultra-reliable and low latency communications (URLLC). The authors in [5] conducted a detailed study on the performance of NOMA with the perfect channel state information (pCSI) condition by analyzing the outage probability. In [23], the authors proposed a NOMA-based computational offloading scheme to reduce the task execution time for users. The authors in [27] minimized the offloading delay and analyzed the convergence speed This treatise focuses on the combination of MEC and NOMA technology under the ipCSI condition in actual scenarios. The NOMA framework studied is applied to the MEC scenario, and the closed-form expressions of the offloading outage probability for paired users (the mth user and the nth user) under pCSI and ipCSI conditions through setting the target transmission rate vn and vm are derived. N represents the total tasks; C number of central processing unit (CPU) cycles demanding for computing one input bit, and fMEC is the CPU frequency at the MEC server
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