# Design and Evaluation of Large-Scale IoT-Enabled Healthcare Architecture
## 3 Proposed IoT-Enabled Healthcare Architecture
### Manager  
Management of the proposed healthcare system represents an important aspect due to the massive number of health devices communicating over a large scale. In addition, a massive number of gigabytes are gathered, sent, and received through the healthcare system. The proposed healthcare system is divided into clusters, each comprising heterogeneous devices such as RFID-based, sensor-based, mobile, and other devices. Each cluster  
Figure 2: The coverage architecture. comprises a homegrown manager (HM). The number of devices in each HM region is determined depending on the size of each cluster and the activities executed within a short interval. Thus, a new HM may be created in the case of overloading on the current HM. Each HM monitors device activities, such as sending and receiving, and the type of transmitted data. The entire healthcare system is managed by the universal manager (UM). Hence, many communications should be achieved between the UM, HMs, computing servers, and devices. These communications are accomplished using control messages. These control messages are sent periodically. The time interval between each message transmission and the next one is determined depending on the message type (sudden event messages should be send regardless the bandwidth factor) and the current available bandwidth. The number of messages is directly proportional to the available bandwidth (i.e., if the available bandwidth is large, the number of management messages will be increased and the time interval between two consecutive messages will be decreased). The control messages transmitted through the healthcare system from UM to HMs, from HMs to UM, from HM to HM, from HMs to their devices in the clusters, and from devices to their HM are classified into four categories. The first category has three types of messages: guidance, stop, and inform. Guidance messages are used when the UM must determine the HM status, such as active or sleep. Stop messages are used to break the connection between some HMs and the healthcare system due to fewer devices in its cluster or insufficient energy to achieve its function (if the HM is an energy-based device). Inform messages are used to send regular information, which may be important or traditional for HMs. The second category has four types of messages: status, threshold, sudden, and prediction. Status messages are sent periodically to reflect the network status in the healthcare system (clusters), which comprises information such as the number of devices, size of transmitted data, and type of data most exchanged. Threshold messages are used when an element of the healthcare system reaches one of its indicators, such as the power or processing unit threshold, which means after a short period, it will be unable to perform its tasks, which leads to finding an alternative. Sudden messages are sent when an unexpected event occurs. Prediction messages are used when the HM has some signs of a future event, such as an increase in the number of devices or a huge data transmission in a special period. The third category has one message, called update. Update messages are sent from one HM to another when a device is transmitted from one cluster to its neighbor or when two HMs must cooperate to accomplish a special function, such as computing. The fourth category has one message, called new. New messages are used to inform the device that a new function is required or a new update has been implemented in the healthcare system. The fifth category has one message, called aggregate. Aggregate messages are used by HMs to gather information about devices under its management. The HM collects data about each device, such as the power consumption rate, number of sent and received bytes within a period, type of device, and other data. In addition, the HM can abstract these data into one result and send it to the UM. Table 1 summarizes the management messages and their description.