## 4 Platform Overview  
The platform described in this paper integrates a vehicular setting with eHealth technology using next-generation IPv6 communication protocols. This section describes the functional elements and roles of the components involved in our platform.  
Figure 3 depicts the overall platform architecture of the integrated testbed. The system includes four functional elements and two types of interactions (short- and long-range).  
From left to right, these functional elements are:  
* The eHealth device provides real time health-related measurements. These measurements can be of a different nature, such as blood glucose levels or oxygen saturation levels. These M2M devices are provided with Bluetooth technology to send recorded data to another authorized peer.
* The cluster head is in the middle of two different communication technologies. On the one hand, short-range Bluetooth technology is used to communicate with M2M Devices and capture the eHealth data. On the other hand, short-range WiFi technology is used to send secure IPv6 packets to the server via the gateway. The cluster head allows us to process the gathered data before sending it to the server along with user comments, which is not possible with a standalone gateway.
* The mobile router provides IPv6 connectivity to in-vehicle devices and a default-route towards the server on the Internet. The gateway uses WiFi to advertise the internal IPv6 prefix to the attached nodes. For long-range communication technology (the path towards the server), only LTE provides a full IPv6 path from end to end. The MR has a powerful CPU and provides some resources demanding networking applications (using cellular interface), which are not available to run on a limited battery power device, like a smartphone.
* The application server collects the data from patients and provides a web interface for doctors to support diagnostics. The software running on the server includes a web server accessed over a secure connection (SSL) and a limited-access database server to gather the data by patients. A Java applet is required to view electrocardiography (ECG) graphs on the doctor's screen.  
Vehicular networking and eHealth technologies are combined (Figure 4) in the form of an ambulance equipped with special telemedicine devices that can record and transmit the patient's vital signs (body temperature, pulse rate, respiration rate, blood pressure) and critical physiological parameters (ECG, blood glucose levels, oxygen saturation levels) to the nearest hospital in order for the resident health professionals to optimally prepare the patient's admittance.  
Figure 3: Platform overview. First step of the testbed integration.  
Assuming a road accident where a serious trauma should be taken into consideration, the ambulance crew has in its disposition a set of handheld lightweight devices that can transfer emergency data to the hospital. The objective in such a situation is to maximize clinical value through a limited set of measurements. All involved devices communicate via Bluetooth to an Android smart phone (cluster head) providing IPv6 connectivity. Figure 5 summarizes the end-to-end message exchange performed during normal use of the platform. The next section describes the gateway configuration phase that does not appear on the latter message exchange.  
Figure 4: eHealth mobile operational scenario. Vital signs recorded by the patient are sent to the expert for diagnosis.  
Figure 5: End to end message exchange diagram. Once the eHealth device is paired to the cluster head (and recognized by the application), the cluster head can be attached to the mobile router and obtain his configuration. The validity of this configuration is assured by the mobile router lightweight configuration protocol presented in Section 5. The cluster head registers at the electronic health record (EHR) and transmit eHealth-related data over TCP/SSL.