# A Mobility Management Using Follow-Me Cloud-Cloudlet in Fog-Computing-Based RANs for Smart Cities
###### Abstract  
Mobility management for supporting the location tracking and location-based service (LBS) is an important issue of smart city by providing the means for the smooth transportation of people and goods. The mobility is useful to contribute the innovation in both public and private transportation infrastructures for smart cities. With the assistance of edge/fog computing, this paper presents a fully new mobility management using the proposed follow-me cloud-cloudlet (FMLC) approach in fog-computing-based radio access networks (Fog-RANs) for smart cities. The proposed follow-me cloud-cloudlet approach is an integration strategy of follow-me cloud (FMC) and follow-me edge (FME) (or called cloudlet). A user equipment (UE) receives the data, transmitted from original cloud, into the original edge cloud before the handover operation. After the handover operation, an UE searches for a new cloud, called as a migrated cloud, and a new edge cloud, called as a migrated edge cloud near to UE, where the remaining data is migrated from the original cloud to the migrated cloud and all the remaining data are received in the new edge cloud. Existing FMC results do not have the property of the VM migration between cloudlets for the purpose of reducing the transmission latency, and existing FME results do not keep the property of the service migration between data centers for reducing the transmission latency. Our proposed FMLC approach can simultaneously keep the VM migration between cloudlets and service migration between data centers to significantly reduce the transmission latency. The new proposed mobility management using FMLC approach aims to reduce the total transmission time if some data packets are pre-scheduled and pre-stored into the cache of cloudlet if UE is switching from the previous Fog-RAN to the serving Fog-RAN. To illustrate the performance achievement, the mathematical analysis and simulation results are examined in terms of the total transmission time, the throughput, the probability of packet loss, and the number of control messages. s 2018184896103390/s18020489 10.3390/s18020489 10.  
edge devices to significantly overcome the disadvantage of cloud-RAN [2] of the heavy burden on front-haul communications and the large amount of radio signal processing operations in the centralized baseband unit pool of cloud-RAN [2]. In an F-RAN, edge node is endowed with caching capabilities and is controllable from a central cloud processor as in a C-RAN [3] to reduce the delivery latency. Mobility management allows UEs or goods to move access multiple points while keeping their data sessions. Distributed mobility management (DMM) is proposed in [4] to distribute the mobility anchors in the data plane in flattening the mobility network such that the mobility anchors are positioned closer to UE [4]. Distributed mobility management for future 5G networks is emerging as a valid framework taking into account the requirements for large traffic in the core and the rise of extremely dense wireless access networks [5]. This work aims to develop a new DMM with low delivery latency using proposed Follow-Me Cloud-Cloudlet (FMCL) concept in F-RANs for the smart city. There is a novel and similar result in [6] to present a Fog-supported smart city network architecture called Fog Computing Architecture Network (FOCAN). To decrease latency and improve energy provisioning and the efficiency of services among things with different capabilities, the applications running on things jointly compute, route, and communicate with one another through the smart city environment. Before describing the proposed follow-me cloud-cloudlet approach, the Follow-Me Cloud (FMC) and Follow-Me Edge concepts are initially described. Follow-Me Cloud (FMC) concept is proposed in [7] to migrate user service by virtual machines (VMs) between data centers (DCs) to support the service migration and continuity due to UE mobility or load balancing. Many mobile applications are heavily based on data and processing capabilities from the cloud [8].