# Hierarchical Mobile Edge Computing Architecture Based on Context Awareness
## 3 Proposed Context-Aware Hierarchical Mobile Edge Computing Architecture  
The point of the proposed context-aware hierarchical mobile edge computing (CoHEC) architecture is to hierarchically deploy MECS at the edge of existing mobile cloud infrastructures in order to provide users with low-latency content delivery as well as efficient use of computing resources and services tailored to various applications. We assumed that the mobile cloud data center was the root of the proposed scheme. First, the proposed CoHEC architecture underwent a profile-based performance scoring process for MECS pre-configured by a network operator or an internet service provider (ISP) to efficiently use edge cloud computing resources and provide services tailored to the various applications of users. Then, when the user requests computing task migration and content delivery to the MECS, each task is executed at the MECS with the computing capability suitable for the service. If the task requires a more powerful computing function, the current MECS migrates the task to other MECS in the upper hierarchy. The detailed operations are as follows. **Phase 1. Edge Performance Scoring:** To utilize MECS efficiently, an \"Edge Performance Scoring\" process is performed that measures the system's own computing capabilities and selects hierarchy layers. For this, each MECS sends a Hierarchy Edge Profile Request (HEPR) message to the central mobile cloud data center to request a profile to perform the Edge Performance Scoring process. Figure 2 shows the format and examples of HEPR messages, and Table 1 shows their fields and meanings. The Edge Identifier field of the HEPR message is an identifier that uses the SHA-256 hash value used for the mobile central cloud data center to identify the MECS requesting the profile. The HEPR field indicates the profile request message, and a timestamp records the starting time of the transmission of the HEPR message in order to recognize the communication status between the mobile central mobile cloud data center and the MECS. On receiving the HEPR message, the central mobile cloud data center sends an HEPR Acknowledgment (HEPRA) message including the profile to the MECS. Figure 3 shows the format and examples of HEPRA messages. The profile contained in the HEPRA message indicates the definition of the task and its own unique identification information that determines whether the service provided by the service provider and the cloud service manager can be appropriately performed. The MECS that has distributed the profile performs the Edge Performance Scoring process based on the contents defined in the profile and sends the Hierarchical Edge Registration Message, including the result, to the central mobile cloud data center corresponding to the root in the hierarchical structure. That is, each MECS transmits a profile request to a central mobile cloud data center and performs a profile-based operation. That is, each MECS carries out a profile-based operation in which each MECS transmits a request to a central mobile cloud data center and then the central mobile cloud \begin{table}
\begin{tabular}{c c} \hline \hline
**Field** & **Detailed Description** \\ \hline Identifier & Edge identification hash value using the SHA-256 algorithm \\ HEPR & Packet type indication field for profile request \\ Timestamp & Field for checking network status \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Hierarchy Edge Profile Request (HERP) message fields and description. Figure 2: Hierarchy Edge Profile Request (HEPR) message format and example. data center transmits the related response to an efficient operation of the MECS and the MECS selects a specific task. **Phase 2. Configuration of the Hierarchy Layer:** In response to the HEPR message, the MECS transmit their results to the central mobile cloud data center. Then, the MECS transmits the Hierarchical Edge Registration (HER) message to the central mobile cloud server, including the execution result and its own identifier as a response to the HEPRA message.