PRINCIPIOS BASICOS DEL CURRÍCULO

are layered, such as the OSI reference model’s seven layers [170] or TCP/IP’s four layers [212]. In any case, the mapping of the layers onto the abstraction levels will be a rather straight forward task once we understand the details of each of the abstraction levels.

All these abstraction levels will be described in further detail in Sec- tion 3.3, but first a terminology will be developed that explains the concepts introduced at of each abstraction level.

3.2

Main Concepts and Terminology

In this section, we define the terminology used in the remaining of the thesis. The terms and concepts are similar to the ones defined in the IST MAGNET and MAGNET Beyond projects [133][153][98] and the PNP2008 project [181], which all are evolutions of [96] and [97]. However, some simplifications have been made since not all aspects of the architecture will be covered in this thesis. Most of the terminology related to the connectivity abstraction level and to non-IP devices have, for instance, been removed.

These concepts are the basis for the technical solutions for personal net- works. As such, they are defined as precisely as possible. It is therefore important to point out that the definition of a Personal Network in this sec- tion is a technical concept that is of a very different nature than the way personal networks have been used earlier in this thesis. Previously, we used personal networks as a vision of what we are trying to achieve; from here on it will be a technical concept that tries to achieve that vision. When we use any of the terms defined in this section in the remaining of this thesis, we will write them with a capital letter to clearly indicate that we refer to the concepts defined here. Hence, Personal Network or PN refers to the term defined here, while personal network refers to the vision of personal networks as introduced in the previous two chapters.

Let us now introduce the concepts and their definition at the three levels of abstraction.

3.2.1

Connectivity abstraction level

Radio Interface A module that can send and receive data packets accord- ing to a particular radio technology and MAC mechanism. This term actually refers to all sorts of network interfaces, not only radio-based interfaces. The term was chosen because of the big interest in radio- based wireless communication and in order to be compatible with the terminology in MAGNET and PNP2008.

Radio Domain A collection of Radio Interfaces using a common commu- nication technology that are controlled by a single MAC mechanism (either centralized, distributed, or a combination of both).

3.2.2

Network abstraction level

Node A communicating entity with one or more Radio Interfaces that im- plements the Internet Protocol (IP). It is understood that a Node also must implement the protocols and mechanisms required to form PNs as outlined in this thesis or in a future PN standard.

Trust Relationship Trust Relationships are established between Nodes that wish to communicate with each other. The Trust Relationship statues a certain degree of trust between the two Nodes. When Nodes come together and want to establish secure communication, they use the Trust Relationship they share, which is instantiated through a cryp- tographic mechanism. Trust Relationships can be permanent, which means they are valid until further notice, or ephemeral, which means they only exist for a limited time during which they are really used. Personal Node A Node related to a given person (e.g., owned by a person)

through a pre-established trust attribute defined by that person. The trust attribute determines to whom the Node is a Personal Node. Two Nodes with the same trust attribute are associated to the same person and are Personal Nodes to each other. All pairs of Personal Nodes have a permanent Trust Relationship between them.

Personal Network (PN) A Personal Network consists of Nodes sharing the same trust attribute with each other. That is, a PN is the collec- tion of all a person’s Personal Nodes and there are permanent Trust Relationships between all the Nodes in a PN.

Cluster A connected network of active Personal Nodes (usually located within a limited geographical area, such as a house or a car). Two Per- sonal Nodes are in the same Cluster if they can communicate with each other using a path between them consisting of only Personal Nodes such that each Personal Node shares a single Radio Domain with the next Personal Node in the path. Hence, a Cluster consists of the Personal Nodes and the Radio Domains that connect them. A single Personal Node with no other Personal Nodes in its communication range is by itself a Cluster (a single Node Cluster).

Foreign Node A Node that has a different trust attribute and therefore is not part of the (same) PN. Foreign Nodes can either be trusted or non-trusted. Whenever trusted, they will typically have an ephemeral Trust Relationship with one or more Nodes in the PN.

Interconnecting Structures Public, private, or shared wired, wireless, or hybrid networks such as a UMTS network, the Internet, an intranet, or an ad hoc network that can be used to interconnect Clusters. We

3.2. MAIN CONCEPTS AND TERMINOLOGY 37

also assume that all Interconnecting Structures are connected to each other.

Gateway Node An active Personal Node within a Cluster that enables con- nectivity to Foreign Nodes and non-PN-enabled devices outside the Cluster. Some Gateway Nodes have access to Interconnecting Struc- tures and can then connect to other distant Personal Clusters via the Gateway Nodes in those Clusters by means of inter-Cluster tunnels. Personal Network Agent The Personal Network Agent or PN Agent is

an infrastructure-based entity accessible through the Interconnecting Structures. Its task is to keep track of each Cluster and their attach- ment points to the Interconnecting Structure so that it can assist in establishing and maintaining inter-Cluster tunnels. It may also be an entry point for Foreign Nodes that want to use Services offered by the PN. Each PN has a PN Agent.

3.2.3

Application and service abstraction level

Service A logical component implemented by a software program running on a Node and that offers something that an application can use through a specified interface. Services have formalized descriptions that enable applications to discover useful Services. The description must describe what the Service offers, how to interface with it, and on which Node it is offered.

Client An application that can use Services. A Service discovery framework must be able to find the Services that Clients require. Clients can run on both Personal Nodes and Foreign Nodes.

Personal Service A Service offered by a Personal Node. The Service is therefore under the administrative control of the user.

Foreign Service A Service offered by a Foreign Node. The Service is not under the administrative control of the user, since it resides on a Foreign Node.

Private Service Private Services are Services accessible only within its PN. That is, the Node of a Client must have a permanent Trust Relationship with the Node of the Service. Furthermore, Private Services are never advertised outside its PN.

Public Service Public Services can be used by both Personal and Foreign Nodes. A Public Service may still require some sort of authentication or Trust Relationship between the Node of the Service and the Node of the Client. Public Services can be offered by both service providers as

well as other person’s Nodes. Public Services on Personal Nodes may be advertised outside the PN.

Service Management Node (SMN) A Service Management Node is a Personal Node in a Cluster that manages the Services and the Service discovery process for that Cluster. Every Cluster must have exactly one SMN. SMNs in different Clusters communicate with each other to provide Service discovery and management for the whole PN.

Service Proxy An application, running on a Gateway Node, which provides one or more Services available outside the PN to Clients inside the PN or the other way around by offering the exact Service itself. When calls come to the Service offered by the Service Proxy itself, it acts as a Client towards the real Service and just relays the Service interactions back and forth between the real Client and the real Service. Thereby, it can connect Clients and Services across the PN boundaries without requiring end-to-end network connections. It constitutes one way of doing foreign communication.

3.2.4

Other concepts

Private Personal Area Network (P-PAN) A Private Personal Area Network is the Cluster around the person. This term is primarily used to describe user scenarios and requirements. In earlier texts, such as [163], the term Core-PAN was used. Nevertheless, these terms have the same meaning.