# A Semantic and Knowledge-Based Approach for Handover Management
## 3 SIM-Know
### Semantic Information Model  
SIM-Know makes appropriate and contextual handover decisions by considering criteria from several information domains (i.e., _Network_, _Application_, _User_, _UserDevice_, and _Handover_) modeled by SIM. We use the Common Information Model (CIM) and the Web Ontology Language (OWL) to carry out SIM (see Figure 1). We adopted CIM [29] because it provides high expressiveness for modeling, for management purposes, information systems, applications, and networks [30]. We used OWL [31] because it enables reasoning in the model and the sharing of knowledge among software agents [32]. In particular, SIM uses OWL classes and properties to characterize HM entirely by modeling the information domains and their relationships. Figure 1 shows the five knowledge domains comprising SIM as superclasses, namely, Network, User, Application, UserDevice and Handover. It is worth noting that the _Handover_ superclass models HM by using the _Initiation_, _Selection_, _Execution_ and _Policy_ classes. The other superclasses represent the information domains containing the parameters used to improve decision making in HM. Each superclass relates to other classes by the _has sub-class_ relationship. The _Initiation_ class models the initiation phase that defines when the selection phase is triggered, which, in turn, is modeled by the _Selection_ class that is responsible for obtaining the candidate networks for performing the handover. The _Execution_ class performs the handover itself, since it allocates and releases AP (i.e., _AccessPoint_ class) and user device (i.e., _UserDevice_ class) resources, represented by the _Resource_ class, which affects the QoS required (i.e., _QoS_ class) by a user application (i.e., _Application_ class). The _Policy_ class represents the policies to apply to the _Network_ class and governs the HM process. An example of a policy is to rank the candidate networks considering some criteria such as users' speeds and their movement patterns. The _Network_ superclass models the characteristics and status of a network by using the _Topology_, _NetworkTraffic_, and _AccessPoint_ classes. The _Topology_ class represents the network's organization, including nodes and links. The _NetworkTraffic_ class represents data  
Figure 1: Semantic Information Model. and control traffic passing by the network. The _AccessPoint_ class models a networking device using wireless technology; this class considers the area covered by the _Cell_ class, which includes the _Range_ class, which contains the _LargeRange_ and _SmallRange_ classes. The _isCoveredByCell_, _hasResource_ and _belongToTopology_ properties represent the _AccessPoint_ class's relationship with the _Cell_, _Resource_ and _Topology_ classes, respectively. The _Resource_ class models the ability to manage the resource consumption of APs located at (_Location_ class) a particular network point. The _User_ superclass models the profile and behavior of the end-users by the _UserPreferences_, _UserHistory_, _MobilityPattern_ and _UserSpeed_ classes. The UserSpeed class includes the _SlowMobility_, _ModerateMobility_ and _HighMobility_ classes in order to model how fast an end-user moves. The _UserPreferences_ class profiles the users with information related to, for instance, network preference by cost and service quality expectation. The _UserHistory_ class models the historical (dis)connection of end-users. The _MobilityPattern_ contains information about the end-users' mobility pattern, which is predictable from their trajectory and velocity. The _Application_ superclass represents end-user applications with the _ServiceProfile_ and _QoS_. The _ServiceProfile_ class models the application's types (e.g., remote surgery, augmented reality, high definition video conferences). The _QoS_ class allows the representation of a set of QoS requirements (e.g., delay, throughput and packet loss) for each type of application.