Ubiquitous computing is shifting healthcare from treatment by professionals in hospitals to self-care, mobile care, home care and preventive care. In order to support the healthcare evolution, a global healthcare system, which links healthcare service providers to an individual's personal and physical spaces, is expected to provide personalized healthcare services at the right time, right place and right manner. This paper presents an overall architecture for such a context-aware healthcare system. The key technologies such as device self-sensing mechanism, context processing framework and a service interoperability platform are identified and elaborated. A personalized healthcare adviser service has been described to illustrate how personalized healthcare can be well supported by the proposed infrastructure.