The objective of this paper is to address the smart innovation ecosystem characteristics that elucidate the assembly of all smart city notions into green, interconnected, instrumented, open, integrated, intelligent, and innovating layers composing a planning framework called, Smart City Reference Model. Since cities come in different shapes and sizes, the model could be adopted and utilized in a range of smart policy paradigms that embrace the green, broadband, and urban economies. These paradigms address global sustainability challenges at a local context. Smart city planners could use the reference model to define the conceptual layout of a smart city and describe the smart innovation characteristics in each one of the six layers. Cases of smart cities, such as Barcelona, Edinburgh, and Amsterdam are examined to evaluate their entirety in relation to the Smart City Reference Model.