Quality of Context: What It Is And Why We Need It

When people interact with each other, they implicitly make use of context information while intuitively deducing and interpreting their actual situation. Compared to humans, IT infrastructures cannot easily take advantage of context information in interactions. Typically, context information has to be provided explicitly. Recently, cellular network operators have been showing interest in offering Context-Aware Services (CAS) in the future. For a service to be context-aware it must be able to use context information in order to adapt its behavior or the content it provides. Examples of CASs are restaurant finders, tour guides and dating services. These services will depend on the availability of context information which must be provided at the right time, in the right quality, and at the right place. The quality of this context information is neither identical to Quality of Service (QoS), nor to the quality of the underlying hardware components, i.e., Quality of Device (QoD). Rather, the precision, probability of correctness, trustworthiness, resolution, and up-to-dateness of context information form a new set of quality parameters which we call Quality of Context (QoC). In this paper, we will discuss what QoC is, what its most important parameters are and how QoC relates to QoS and QoD. These three notions of quality are unequal, but not unrelated. Based on several examples we will show the interdependence between them. We will argue that QoC as a new notion of quality is necessary to allow for the provisioning of CASs in an interorganizational manner.