5G network is an inevitable trend in the development of mobile communications. Mobile cloud computing is a more promising technology for 5G networks. This paper proposes a hierarchical distributed cloud service network model, which is composed of three layers: “access cloud + distributed micro cloud + core cloud”. On the basis of access to the cloud, a distributed micro cloud system is deployed to migrate the service capabilities of the remote core cloud server to the local area. This paper proposes a task offloading assignment algorithm in a small cell cloud scenario. This algorithm establishes a SCC (Small Cell Cloud) based on the channel quality between small cells and the remaining available computing resources, and allocates the load to each small cell in the SCC according to the channel quality and the remaining available computing resources. Simulation results show that this solution can improve the utilization of wireless and computing resources in the small cell cloud computing scenario, and improve the user QoE (Quality of Experience). In order to make the system operate normally under heavy load, this paper proposes a feedback adaptive random access strategy based on the adaptive random access model. This can ensure that the throughput rate does not decrease under heavy load conditions, and at the same time, the average access delay of the existing system is reduced. When the arrival rate of user requests gradually increases, the throughput rate of RA-RACH access will continue to decrease due to collisions until it approaches below 0.1. In the state where the number of users is low and the load is lighter, both RA-RACH, AC-RACH, and FC-RACH have a higher access success rate. But as the load continues to increase, RA-RACH will quickly drop to 0.

5G网络是移动通信发展的必然趋势。移动云计算是一项更有前景的 5G 网络技术。本文提出了一种分层的分布式云服务网络模型，它由三层组成：“接入云+分布式微云+核心云”。在接入云端的基础上，部署分布式微云系统，将远程核心云服务器的服务能力迁移到本地。本文提出了一种小小区云场景下的任务卸载分配算法。该算法根据Small Cell之间的信道质量和剩余可用计算资源建立SCC（Small Cell Cloud），并根据信道质量和剩余可用计算资源为SCC中的每个Small Cell分配负载。仿真结果表明，该方案能够提高小基站云计算场景下无线和计算资源的利用率，提高用户QoE（Quality of Experience）。为了使系统在重负载下正常运行，本文提出了一种基于自适应随机接入模型的反馈自适应随机接入策略。这样可以保证在重负载情况下吞吐率不下降，同时降低现有系统的平均访问延迟。当用户请求的到达率逐渐增加时，RA-RACH接入的吞吐率会因为冲突而不断下降，直到接近0.1以下。在用户数较少负载较轻的状态下，RA-RACH、AC-RACH、FC-RACH均具有较高的接入成功率。