# Rebirth of Distributed AI--A Review of eHealth Research
## 8 Selected IoMT-Based Health Applications
### Wearable and Implantable Devices  
Wearable or implantable devices are other examples of IoMT. They allow patients to send their health information to doctors to better diagnose diseases and track and prevent chronic illnesses. Proactive monitoring helps in predicting the likelihood of expected disease development, such as predicting a heart attack, or an epilepsy fit before it happens. Examples are:  
* An insulin pump. * A wearable smart asthma monitoring device. * A watch to monitor depression. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Data Type** & **Latency** & **Data Rate** & **Packet Loss Rate** \\ \hline \hline \multicolumn{1}{l}{Haptic feedback} & 3–5.5 ms & 128–400 Kbps & \textless{}10 power-4 \\ \hline
3D Camera Flow & \textless{}150 ms & 137 Mbps–1.6 Gbps & \textless{}10 power-3 \\ \hline \multicolumn{1}{l}{Physical vital signs} & \textless{}250 ms & 10 kbps–1.536 Mbps & \textless{}10 power-3 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Minimal communication requirements for telesurgery. * A blood pressure monitoring device. * An ECG monitoring system. For a comprehensive survey and classification of commercially available wearables and research prototypes we advise reading [52]. The current devices on the market are still limited in fulfilling the envisioned objective, mainly due to the wireless communication limitation. Therefore, current research is focused on enhancing the sensing techniques to become fully automatic, more accurate, reliable, cost-effective, and noninvasive. These devices gather data from very different appliances, from nano to macro, and communicate in heterogeneous types of channels, from chemical to radio or free-space optical [53]. Design requirements of such solutions would be:  
* Ultra-low-power communication: unlike telesurgery, where surgery time is bounded and hence higher power consumption communication is expected and can be accommodated, in wearable or, especially, implantable devices, the longevity of battery in the sensors and other devices is very important. Part of the user experience and convenience is to limit the need for replacement or recharging of these nodes. We see improvement in battery life, but this is not enough. For continuous and smooth remote monitoring, energy-efficient schemes such as in the algorithm or protocol for communication are required [54]. For example, in [119], a prototype is introduced for a wrist-worn device for the monitoring of pervasive personalized environmental parameters. For the objective of extending the battery life, when the level of battery power is decreased, the sampling rates of gas sensors and sound level detectors are reduced accordingly. * Highly accurate localization and positioning. Such a high level of accuracy can be achieved through THz technology with simultaneous localization and mapping-based techniques. Compared to 5G meter-level positioning precision, 6G will provide 10 cm indoor and 1 m outdoor precision in positioning [28]. * Interoperability: or the ability of heterogeneous devices to communicate and exchange data. Lack of universal standards for interoperability in the different levels (e.g., application, network) can impede IoT success [29]. Nevertheless, some effort has begun by standardization bodies such as OMA [120], 3 GPP [121], and ETSI [122]. Compared to the EHRs, which represent a limited volume of data that reside in silos in each health institution, the data from wearable devices represent a much bigger, diverse, and actual today's real-world patient population. However, what remains common for both is that data privacy must remain intact. Here comes the role of FL FL will enable training a model collaboratively by thousands or even hundred of thousands of wearable devices in an efficient and economical way. Achieving robust implementations of FL in this scenario can make a huge progress in the massive and remote healthcare system.