QoS-aware model-based systems design using systems modeling language

Abstract

Among several parameters involved in Systems Design (SD), Quality of Service (QoS) is a critical factor that constrains design decisions. QoS reflects the operating levels of a system under certain conditions that affect the quality of the provided functionality. Despite it being a clear indicator of the quality of services that end-users of a system are expected to enjoy, there is no complete framework that integrates QoS into design efficiently using Model-Based Systems Design (MBSD) and Systems Modeling Language (SysML). Moreover, the current version of SysML does not directly address QoS concepts. However, the primitive notion of SysML requirements can be used and extended to describe and manage QoS, capturing what the system provides to its users, service-wise, rather than encapsulating system behavior. To evaluate such requirements one has to assess system outcomes, via system analysis, to verify whether the latter satisfy the users (or not). Satisfying certain QoS requirements requires a designer to decide upon different key aspects of the system, such as its configuration. Serving QoS is further tied to the costs needed to acquire/operate the system. The aim of this work is to explore QoS using MBSD and SysML. We build upon the framework of Friedenthal, and Systems Modeling Toolbox (SYS-MOD), and we extend them to manage QoS in an integrated SysML framework. Moreover, we show and validate the applicability of our framework focusing on a Remote Elderly Monitoring System (REMS), that belongs in the healthcare domain. In that particular context, different configuration solutions of the system installed in the patients' home for monitoring their health conditions are explored, considering that the patients' different QoS and budget requirements should be satisfied. Therefore, assessing QoS can contribute to a more effective design and implementation of such systems enhancing user satisfaction.