## 3 Proposed Protocol Architecture
### Mobility Scenario in IP-WSN  
We consider a state-of-the-art technology based patient care unit in a specialized hospital to depict different types of mobility scenarios [12]. We describe the patient care unit of the hospital environment in Section 3.3 with the help of Figure 3. The mobility issues considered in this scenario are: Case-I: Movement of nodes within the same SMAG domain, Case-II: Movement of nodes between different SMAGs of the same IP-WSN domain, Case-III: Movement of nodes between different SMAGs of different IP-WSN domains, Case-IV: Movement of a SMAG domain within the same IP-WSN domain, Case-V: Movement of a SMAG domain between different IP-WSN domains, Case-VI: Patient monitoring in personal home environment. These scenarios are explained below:  
Case-I: In this case, the mobility of the nodes will be handled by the respective SMAG, without the involvement of the border router in the process. This is the simplest mobility scenario that arises frequently in hospital management. For example, a patient can move within the same SMAG domain of the hospital for different purposes such as for exercise and fresh air.  
Case-II: In this case, mobility will be handled by the appropriate SMAG with minimal interaction from the border router. The initial coordination will be performed by the border router alone; then the SMAG will oversee the remaining procedures. In our patient care scenario, a patient can move from one SMAG domain to another in the same IP-WSN domain of the patient care unit.  
Case-III: In this case, mobility is among different IP-WSN domains, sometimes using the public Internet domain. In the proposed patient care unit, a patient can move on an emergency basis from one IP-WSN domain of a hospital to another IP-WSN domain of the same hospital.  
Case-IV: In this case, the scenario is based on the network mobility (NEMO) protocol [13]. It is confined to the same IP-WSN domain. In our patient care scenario, a patient with the whole set up can move from one location to another location within the same IP-WSN domain. In this scenario a patient's body is considered as a SMAG domain, so it is a SMAG domain movement within the IP-WSN.  
Case-V: This case is also based on the NEMO approach. In this scenario a patient's body is considered as a SMAG domain. In the patient care scenario, a patient with its setup considered as a SMAG domain can move from one IP-WSN to another IP-WSN, so it is SMAG domain movement among different IP-WSN domains.  
Case-VI: Due to the increasing number of people in the aging demographic group, we consider this case so that a patient can be monitored continuously from the patient's personal home care. In this case the home care unit will be fully automated with IP based sensors and other state of the art technology.  
Although some of the mobility scenarios may seem complicated in the case of an IP-based wireless sensor network, still they have been considered an issue for future research. Because of the essence of huge deployment of IP sensor network in health care, departmental store and industrial automation, this mobility scenario will eventually come true in the near future.