## 3 The LOBIN Prototype: A Practical Study Case
### System Description
#### 3.1.1 Healthcare Monitoring Subsystem  
The Healthcare Monitoring Subsystem represents the BAN of the LOBIN project and it is mainly based on smart fabrics and e-textile. Thus, the LOBIN BAN can be classified as a wired solution from the communications point of view. Other surveyed WHMS have opted for wireless solutions, such as Bluetooth and IEEE 802.15.4 (e.g., [PERSON] _et al._[26, 27], [PERSON] _et al._[49], and [PERSON] _et al._[43]). There are also WHMS that use proprietary technologies, such as [PERSON] _et al._[20], which uses RF-transmitter at 869.700 MHz, or Human\(++\)[34], which uses RF 2.4 GHz ISM. Other WHMS work with specific technologies, such as MICS (e.g., [PERSON] _et al._[45]) in the medical field or ANT (HipGuard [39]) in the sports sector. The Healthcare Monitoring Subsystem consists of the set of smart shirts to be worn by the patients. Every smart shirt is equipped with physiological sensors and a WDAD, which processes the data coming from the sensors and transmits them wirelessly. The WDAD is further divided into two different PCBs: the Data Acquisition and Processing Board (DAPB) and the WTB. Figure 4 sketches how the Healthcare Monitoring Subsystem works. The physiological sensors are in charge of measuring raw data that will be further processed in order to obtain the required biomedical parameters. The available sensors are: the e-textile electrodes, the accelerometer, and the thermometer. The e-textile electrodes are used to measure the bioelectric potential of the human body and are integrated into the smart shirt, as shown in Figure 5. The signals provided by the 3-axis accelerometer are used to detect patient movements and determine whether the patient is laying down or moving about in order to aid appropriate diagnosis. The thermometer measures the body temperature and it must be in direct contact with the skin of the patient. Both the 3-axis accelerometer and the thermometer are integrated into the WDAD, as it is also shown in Figure 5.  
Figure 4: Healthcare Monitoring Subsystem Block Diagram. The DAPB collects all the data from the sensors, processes them, merges them all together in a message (_i.e._, the healthcare-monitoring subsystem frame) and sends them via a serial port to the WTB. The WTB builds a new packet by adding information related to the WCI to the message coming from the DAPB and transmits it wirelessly. Both the DAPB and the WTB share the same battery so they can be integrated into a common PCB for commercialization. Figure 6 shows the developed hardware. Figure 5: Physiological Sensors. Figure 6: (**a**) Wearable Data Acquisition Device (WDAD) (**b**) Healthcare Monitoring Wireless Transmission Board (WTB). As has already been mentioned, a healthcare-monitoring frame to pack all the sensitive information in just one message is defined. All the physiological parameters are sampled every 4 ms. However, this message is only transmitted after collecting 65 ECG samples. This value is determined by the size of the frame resulting from the healthcare-monitoring frame together with the additional routing information, needing to be as close as possible to the 802.15.4 MTU (102 bytes). As a result of this decision, efficiency is maximized and transmission rates decreased, which in turn reduces collisions in the WCI. Thus, from the Management Subsystem point of view, the rest of the parameters apart from the ECG are sampled every 260 ms. Table 39 summarizes the most important features of the parameters transmitted in this message. Among the cardiac monitoring systems studied, the key monitored parameter is the ECG. Many projects, such as RECAD [21], [PERSON] _et al._[32], MASN [38], or GeM-REM [52], are based only on the monitoring of such parameter. Other projects, like LOBIN, monitor additional parameters, such as temperature, activity index and the relative position of the body, which can help caregivers to understand the changes in the ECG of the patient.