# ZONE-Based Multi-Access Edge Computing Scheme for User Device Mobility Management
## 3 Proposed Zone-Based MEC Architecture for User Device Mobility Management
### A Scheme to Support User Mobility Management within the Zone  
**Step 1. Registration of access MECS to configure internal Zone:** In the MEC environment, the proposed scheme to support continuous service even when user devices move frequently manages access MECSs with the concept of Zone. The proposed scheme uses EMO to configure Zone with access MECS and manage the access MECS located in Zone. To construct an internal Zone in the proposed scheme, it is assumed that each access MECS has EMO information preset by the carrier operator. First, the access MECS transmits the access MECS registry (AMR) message containing its own information to the EMO that is preset by the carrier operator before starting the service in order to configure the Zone. Figure 2 shows the format and example of the AMR message. The Zone Identifier field of the AMR message is set using information from the EMO preset by the carrier operator, which contains the information to identify the Zone. Access MECS Identifier refers to the unique information of access MECS such as the universally unique identifier (UUID). In addition, the access MECS address field indicates the address of the access MECS itself that is identifiable in EMO. Finally, the Signature field is the secure hash algorithm (SHA) value generated by using the information of the Zone identifier and the access MECS identifier. It is used to check the validity after registering the access MECS in the Zone. **Step 2. Creation of EMO management list for access MEC management:** The EMO, which receives AMR messages from access MECS, generates Edge Management List (EML) to efficiently perform mobility management of access MECS and mobile user located in its internal Zone. The EML is generated using the information of the message sent from the access MES and additional information (i.e., location, accessibility, etc.) from access MECS preset by the carrier operator. Figure 2: AMR message format and example. Figure 3 shows an example of the EML list generated by the EMO. The identifier and address fields of access MECS represent the unique identifier and address of access MECS, respectively. The Signature field represents a signature field in the AMR Message sent from the access MECS and is used to check the validity of the access MECS. Finally, the group tracking area field is a field of information for managing mobility generated by EMO based on AMR messages from access MECS located on its Zone to provide an efficient mobility experience for mobile users. EMO generates group tracking information by referring to AMR messages sent from access MECS and the EML information created by itself for continuous service provision even when mobile users are on the move. Group tracking information, which consists of information from adjacent access MECS, is transmitted to the access MECS by the EMO to manage the mobility of the mobile user so that it is possible to efficiently respond even when the mobile user frequently moves. In other words, EMO generates EML by combining information transmitted from access MECS and various information preset by carrier operator and generates group tracking information for mobility management by using generated EML and transmits it to access MECS. Thus, it is possible to provide continuous service even when mobile users move frequently. **Step 3. Movement Indication:** To recognize that the mobile user has moved in the proposed scheme, access MECS periodically broadcasts the access MECS status (AMS) message containing its own information. Since the AMS message includes information on the Zone, access MECS and neighboring access MECS, the mobile users receiving the AMS message can determine whether they have moved. Figure 4 shows the format and example of the AMS message. The Zone identifier field is identification information of the Zone created by the EMO, and it is possible to detect whether or not the mobile user has moved to other Zones. Mobile users moving to other Zones are described in detail in the next section.