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.

本文提出了一种基于非正交多址（NOMA）的移动边缘计算（MEC）系统，其中成对用户（第m个用户和第n个用户）在不完善的信道状态信息下将任务卸载到MEC服务器上（ipCSI）条件。为了评估NOMA-MEC系统在ipCSI条件下对性能的影响，本研究推导了两个用户在ipCSI和完美信道状态信息（pCSI）条件下的卸载中断概率的新的精确和渐近表达式。根据理论推导，在ipCSI和pCSI条件下，第n个用户的分集阶数分别为零和n，而远方用户的分集阶数均为零。。此外，我们还研究了延迟受限传输中NOMA-MEC的系统吞吐量和能效。数值结果表明：（1）NOMA-MEC的卸载中断性能优于时分多地址（TDMA）；（2）ipCSI下的配对用户的卸载性能比pCSI差；（3） ）与TDMA-MEC系统相比，NOMA-MEC系统实现了更高的吞吐量和能效。