## 4 Performance Analysis and Evaluation
### Signaling Cost Analysis of IP-WSN  
We have evaluated our proposed model based on signaling cost, mobility cost and energy consumption. In the subsequent section we discuss the signaling cost and energy consumption analysis. Mobility cost is evaluated based on signaling cost. To evaluate total signaling costs, we compare the results of the analytical model of IP-WSN with those of MIPv6 and PMIPv6. We already mentioned that the proposed global IP-WSN architecture is based on SPMIPv6 which is a sensor network-based PMIPv6 protocol. Figure 14 depicts the analytical model for the performance analysis of the proposed architecture. It consists of two different IP-WSN domains which are connected over the PMIPv6 based Internet. This figure is the analytical representation of Figure 1 which depicts the global IP-WSN architecture. We may consider the individual IP-WSN domain as the different floor of the patient care unit. Distance between SMAG and IP sensor node is denoted by \(\text{D}_{\text{sn-smag}}\) and the distance between SMAG and border router is denoted by \(\text{D}_{\text{smag-BR}}\). The corresponding node (CN) considered as the specialist doctor is communicating with the visiting doctor. There are some visiting doctors who see the patient on a continuous basis. In this analytical model, different distances are used for calculating signaling cost. Figure 14: Analytical model for the performances analysis. Signaling cost is defined as the total cost of signaling traffic overhead which in turn, is the total number of control messages exchanged between different nodes, so the unit of signaling cost is the number of control message exchanged among different nodes. There may be five types of mobility scenarios which has already been discussed in an earlier section. If patients move to a remote site then the signal will be transmitted through the Internet domain, otherwise signal transmission will be restricted within the IP-WSN domain. From Equation (9) the total signaling cost (SigCost\({}_{\text{mipv6}}\)) of the proposed IP-WSN scheme based on MIPv6 is calculated by summing up the individual cost of intra-IP-WSN mobility (M\({}_{\text{intra-ip-wsn}}\). C\({}_{\text{sd}}\)) and inter-IP-WSN mobility (M\({}_{\text{inter-ip-wsn}}\). (C\({}_{\text{sd}}\) + C\({}_{\text{bu}}\))). Where, C\({}_{\text{sd}}\) and C\({}_{\text{bu}}\) are the sensor mobility cost and binding update cost respectively. Table 1 describes different symbols used in the equations. \[\text{SigCost}_{\text{mipv6}}=\text{M}_{\text{intra-ip-wsn}}\text{.}\text{C}_{ \text{sd}}+\text{M}_{\text{inter-ip-wsn}}\text{.}\text{(C}_{\text{sd}}+\text{ C}_{\text{bu}}\text{)} \tag{9a}\]  
where C\({}_{\text{sd}}\) and C\({}_{\text{bu}}\) are calculated in term of MIPv6 as follows:  
\[\text{C}_{\text{sd}}=\alpha\text{.}\left(\text{ RS}_{\text{mipv6}}+\text{RA}_{\text{mipv6}}\text{ }\right)\text{D}_{\text{sn-smag}} \tag{9b}\] \[\text{C}_{\text{bu}}=\alpha\text{.}\left(\text{BU}_{\text{mipv6}}+\text{BA}_{\text{ mipv6}}\right)\text{D}_{\text{sn-smag}}+\beta\text{.}\left(\text{BU}_{\text{mipv6}}+\text{BA}_{ \text{mipv6}}\right)\text{D}_{\text{smag-BR}} \tag{9c}\]  
From Equation (10) the total signaling cost (SigCost\({}_{\text{pmipv6}}\)) of the proposed IP-WSN scheme based on PMIPv6 is calculated by summing up the individual cost of intra-IP-WSN mobility (M\({}_{\text{intra-ip-wsn}}\). C\({}_{\text{sd}}\)) and inter-IP-WSN mobility (M\({}_{\text{inter-ip-wsn}}\). (C\({}_{\text{sd}}\) + C\({}_{\text{bu}}\))).