## 2 Literature Review
### The Definition of IIC  
The definition of IIC is yet to be universally agreed upon. [PERSON] [21] defined IIC as \"a knowledge-based industrial cluster, which means that enterprises including manufacturers, suppliers and service providers form regional or urban clusters across multiple industries\" [22]. Affected by the supply chain, the cooperation intensity of enterprises in the cluster is higher than that outside of the cluster. Innovation clusters have been identified as a means of efficiently satisfying market requirements and encouraging the development of innovative technologies, allowing knowledge-based economies to access knowledge resources more easily [23; 24]. Moreover, IIC has played a crucial role in supporting high-tech enterprises in the incubation environment [25]. Knowledge acquisition is affected by spatial distance, which means that enterprises within IIC can assimilate knowledge more easily than enterprises outside, giving them a better chance to use innovative knowledge resources to develop and obtain new market share [26; 27]. Meanwhile, IIC can gather a large number of technological talents, which can significantly improve the efficiency of R&D within the cluster [28]. Especially, adopting IIC is a strategy for SMEs enhancing market competitiveness by reducing the investment related to logistics and electricity [29]. For SMEs, these expenses constitute a larger proportion of their overall costs than larger enterprises. However, it should be noted that most IIC are just one chain of multiple technologies, which means the absence of certain technologies can lead to the incompleteness and inefficiency of an industry's operation. Thus, [PERSON] et al. [30] further define IIC as \"acomplex and sophisticated form of cooperative innovation, which is embedded in every step of the industrial chain\", thus forming an innovation system of technology integration and expansion.  
Besides academic definitions, governments and authorities have also proposed different definitions of IIC. For example, the United States National Research Council [31] defines regional IIC as \"the agglomeration of enterprises providing innovative products and services, as well as suppliers and research institutions\". In IIC, members have gathered a large number of knowledge- and skill-related resources and benefit from cooperative exchange. More than this, China Ministry of Science and Technology [11] defines IIC as \"the enterprises in the industrial chain. R&D and service institutions gather in the region and form a competitive cross-industry and cross-regional industrial organization system through divisional works and collaborative innovation\".  
The differentiation of IIC from science parks and traditional industrial clusters is evident in current definitions. First, IIC focus on specific industries, and its spatial distance could be far greater than that of traditional science and technological parks [32]. Meanwhile, the development of IIC depends on the knowledge and technological resources within the cluster, and this emphasizes the importance of the coordination and collaboration of diverse technologies within the industry. This aligns with the characteristics of the existing science and technology industry, which is characterized by many enterprises, knowledge centralization, and technological diversification. In contrast, traditional industrial clusters rarely involve the level of industrial technology and primarily focus on the economic or social yield [33].