Technologies to Improve the Quality of Handovers: Ontologies, Contexts and Mobility Management

Technologies to Improve the Quality of Handovers: Ontologies, Contexts and Mobility Management

Edson Moreira (University of Sao Paulo, Brazil), Roberto Yokoyama (University of Sao Paulo, Brazil), Renata Maria Vanni (University of Sao Paulo, Brazil) and Bruno Kimura (University of São Paulo, Brazil)
DOI: 10.4018/978-1-60960-042-6.ch034
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Modern life makes people internet-dependents. They want to move connected and care for always getting the best options for connectivity, hoping between providers. Freedom for choosing providers and the business options which these exchanges can offer are the motivations for this chapter. After pointing out some characteristics which make the basics of the current handover technologies, we describe an information infrastructure, based on context and ontologies which can be used to foster an intelligent, efficient and profitable scenario for managing handovers in the Next Generation Networks. Some experiments are described and the potential of using these technologies are evaluated.
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A Taxonomy For Handover Management

Various terms and classifications for the handover process are found in the literature, these classifications vary with the perspective and approach in which mobility aspects of the handover process are analyzed. The distinctions can be made in accordance with the scope, coverage range, performance characteristics, state transitions, types of mobility, and handover control modes.

The most common classification outlooks are: layer, system, technology, decision, performance, procedure and connection. Some classification and types of handover perspectives are briefly presented in Table 1, which was created based on RFC 3753.

Table 1.
Classification of handovers
Layer  LinkWhen the transition point of access is transparent to layer 3, i.e., there is no new IP address.
NetworkIs the mobility management through a protocol that supports mobility, since a new IP address is assigned to the Mobile Node.
  TransportIsolates the network layer, that is, is independent of the concept of the network source or additional infrastructure, since the mobility management is performed end-to-end.
ApplicationAn application manages the handover.
System  Intra-SystemChanges are under the same domain, that is, when it occurs between the same systems.
  Inter-SystemWhen transitions occur between different domains, requiring macro-mobility support and includes assigning a new IP address for the Mobile Node.
TechnologyHorizontal or HomogeneousDiscriminated when the Mobile Node is moved between access points of the same communication technology.
Vertical or HeterogeneousDiscriminated when transitions occur between different communication technologies.
Decision  Helped by the Mobile NodeInformation and measurements from the Mobile Node are passed to the Access Router that decides the handover performance.
  Helped by the Mobile NodeWhen the Network Access collects information that can be used by the Mobile Node in the handover decision.
UnattendedNo information to assist in the handover decision is exchanged between the Mobile Node and the Access Router.
Performance  SmoothThe main objective is to minimize packet losses, with no concern for additional transmission delays.
  FastAims to minimize latency, without worrying about packet losses.
  TransparentIs considered transparent, in practice, when applications or users do not detect any changes in service that can be seen as quality deterioration.
Procedure  ProactiveIs characterized by a planned exchange through the monitoring of network parameters, that is, made before disconnection.
  ReactiveIs an unexpected transition, there are no indications to assist in the transition to the new network.
Connection  Make-before-break
  or soft handover
Allows the Mobile Node to simultaneously connect to the next access point and continue with the original one during the handover.
  Break-before-make or hard handoverIt only connects to one access point at a time, that is, it disconnects from the current access point to then connect to the next one.

Key Terms in this Chapter

Mobile IP: is an Network-level Mobility Management. An inherited model from cellular network (registration dependency and stream forwarding by relay entities) is adapted to the concept of a Home in Mobile IP. Thus, a Home Agent (HA) is responsible for managing mobile nodes anchored to their Home Networks (HN).

Network-level Mobility: reproduces a behavior similar to the L2 infrastructure in cellular network architectures by providing support for mobility at L3. This is obtained by a special capability in the addressing and packet forwarding configurations when a node is moved. Except for a time disruption, upper layers do not need to be concerned about the L3 handovers.

Context Aware Systems: is a system that makes use of context information to provide services relevant to the user. The service relevance depends on the user's specific task. In NGN, the context information, in which surrounds the mobile device and the network, is used to provide or improve network services by adapting the user's device to the environment conditions.

Ontology: is a formal representation and shared conceptualization of a set of concepts within a domain and the relationships between the concepts. An ontology provides a shared vocabulary which can be used to model a domain.

Handover: According to the RFC 3753, handover, also called handoff, is basically the process by which an active MN, in its active state, changes its point of attachment to the network, or when such a change is attempted. However, as described in this chapter, there are several classifications of handovers.

IEEE 802.21: is a standard that aims at optimizing handovers between heterogeneous IEEE 802 networks access, as well as facilitating handovers between IEEE 802 networks and cellular networks. In order to do so, this standard defines commands (to trigger decision-making) and events (of link conditions) by using information of MN and of network.

Application-level Mobility: the impact of L3 handovers (changing of IP over ongoing transmissions) is handled at the application. The mobility support is faced from an end-to-end communication concept. Doing so, no additional network infrastructure is required (no need for agents), deployment can be easier (only end-points are involved), and route optimizations and interoperability are natural features (legacy transport protocols are unchanged).

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