## 2 Survey of Existing HCWSNs
In MEDiSN, 98% of data packets were delivered when tests were conducted in a real hospital deployment, and the PDR of MASN when there are up to 100 sensors in the network exceeds 90%. [PERSON] _et al._[21] states that a reliable HCWSN should have a PDR of at  
Figure 3: Overview of MASN architecture and operation. least 90%. Therefore, MEDiSN and MASN meet the reliability requirements while CodeBlue requires additional mechanisms to possibly improve its reliability. Descriptions for energy efficiency were provided only for MEDiSN and MASN. With the use of adaptive duty cycling, the PMs in MEDiSN have a lifetime of approximately 4.62 days, which is a promising result. In MASN, it is shown that most of the sensor battery is consumed in radio communication (65%), which is not energy efficient. This can be largely attributed to the networking protocol design, and some improvements needs to be made to make it more efficient. All three HCWSNs utilize different routing mechanisms. CodeBlue uses the ADMR protocol for multicast routing, MEDiSN optimizes many-to-one and one-to-one communication without explicitly using multicast and MASN uses a cluster-based communication protocol to group sensor nodes. All three systems effectively communicate data from multiple sensors to a sink, so the different routing protocols are acceptable although only CodeBlue uses multicast. The support of node mobility is another key requirement for HCWSNs. CodeBlue deals gracefully with node movement with mobility rates that are typical of patients. MEDiSN succeeded in consistently monitoring patients when they were mobile in a real hospital deployment. Unfortunately, MASN cannot achieve real-time data collection if the patients exhibit mobility because the latency increases substantially as the mobility speed increases. Lastly, we assess the HCWSNs in terms of their ability to deliver packets in a timely manner (\(<\)5 s [21]). The end-to-end latency in CodeBlue for paths that spanned up to 7 hops was no more than 200 ms. The end-to-end latency in MEDiSN never exceeded 2 s, and the time to reach the sink from the time an event is detected by the sensor node is approximately 1 s for MASN. \begin{table}
\begin{tabular}{|p{85.4 pt}|p{85.4 pt}|p{85.4 pt}|p{85.4 pt}|} \hline
**Requirements** & **CodeBlue [13]** & **MEDiSN [19]** & **MASN [20]** \\ \hline Operational & 30 Node _Ad Hoc_ & Dedicated Wireless Sensor & Simulation-based _Ad Hoc_ \\ Environment & Sensor Network & Network in Hospital Deployment with 6 RPs and 8 PMs & Sensor Network \\ Supported Application & Medical Care and Disaster Response & Emergency Detection & Real-time collection of ECG Data \\ Reliability & None & Two-Tier Architecture with Dedicated Wireless & Dynamic Reliability \\ Mechanism & (Unreliable Multicast) & Backbone and Optimized Rate Control Protocols & \\ Scheme for Energy & Not Provided & Division of functionality between acquiring (PM) and relaying (RP) data & Energy-aware cluster formation using energy level determination of sensor nodes \\ Routing Methodology & Multicast & Many-to-one and one-to-one communication & Intra-Cluster and Inter-Cluster Data Relay \\ Techniques for Mobility Support & Periodic Flooding for Route Discovery & PMs periodically select the best RP to forward their data to & None. Does not support real-time data collection under mobility conditions \\ \hline \end{tabular}
\end{table} 
Table 1: Characteristics of CodeBlue, MEDiSN and MASN HCWSNs.