Under traditional rule-based reasoning in smart environment

the inference engine deployed in gateway collects data from various sensors to match the rules

which undertakes whole reasoning work. In current research

we use Rete algorithm to construct an inference network by rules and then allocate the Rete inference nodes to smart nodes for collaborative reasoning based on fog computing

therefore

the allocation mechanism becomes crucial. In this paper

we utilize the regularity of rules triggered under the influence of activities to design an algorithm CoA (Clustering of Activity)

which clusters activities and respectively constructs the inference networks

subsequently

we calculate the shortest path between smart nodes and substitute the results into AAoRN (Allocation Algorithm of Rete Inference Nodes)

which is proposed to overcome hierarchical delay for optimally allocating each inference node. Theoretical analysis and experimental results show that the proposed mechanism efficiently utilizes the resources and has reduced the delay by about 55%.