Within this book the fundamental theoretical background of indoor positioning systems is analyzed and potential industries for such systems as well as their business cases are identified. Based on expert interviews the added values within those businesses created by the identified business cases are determined. Afterwards, the findings of a technical feasibility study are contrasted against the main smartphone platforms and their capabilities, building the foundation for a smartphone based indoor positioning system architecture model. The therefore created architecture fulfills all requirements of the analyzed industries while taking the smartphone platform capabilities into account, leading to a cross-platform, positioning technology independent, service-oriented indoor positioning architecture.